ML19317E533
| ML19317E533 | |
| Person / Time | |
|---|---|
| Issue date: | 07/09/2019 |
| From: | Charles Brown Advisory Committee on Reactor Safeguards |
| To: | |
| Brown, C, ACRS | |
| References | |
| NRC-0434 | |
| Download: ML19317E533 (194) | |
Text
Official Transcript of Proceedings NUCLEAR REGULATORY COMMISSION
Title:
Advisory Committee on Reactor Safeguards NuScale Subcommittee Meeting Docket Number:
(n/a)
Location:
Rockville, Maryland Date:
Tuesday, July 9, 2019 Work Order No.:
NRC-0434 Pages 1-152 NEAL R. GROSS AND CO., INC.
Court Reporters and Transcribers 1323 Rhode Island Avenue, N.W.
Washington, D.C. 20005 (202) 234-4433
NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.
(202) 234-4433 WASHINGTON, D.C. 20005-3701 www.nealrgross.com 1
1 2
3 DISCLAIMER 4
5 6
UNITED STATES NUCLEAR REGULATORY COMMISSIONS 7
ADVISORY COMMITTEE ON REACTOR SAFEGUARDS 8
9 10 The contents of this transcript of the 11 proceeding of the United States Nuclear Regulatory 12 Commission Advisory Committee on Reactor Safeguards, 13 as reported herein, is a record of the discussions 14 recorded at the meeting.
15 16 This transcript has not been reviewed, 17 corrected, and edited, and it may contain 18 inaccuracies.
19 20 21 22 23
1 UNITED STATES OF AMERICA 1
NUCLEAR REGULATORY COMMISSION 2
+ + + + +
3 ADVISORY COMMITTEE ON REACTOR SAFEGUARDS 4
(ACRS) 5
+ + + + +
6 NUSCALE SUBCOMMITTEE 7
+ + + + +
8 TUESDAY 9
JULY 9, 2019 10
+ + + + +
11 ROCKVILLE, MARYLAND 12
+ + + + +
13 The Subcommittee met at the Nuclear 14 Regulatory Commission, Two White Flint North, Room 15 T2B10, 11545 Rockville Pike, at 1:00 p.m., Joy Rempe, 16 Chair, presiding.
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2 COMMITTEE MEMBERS:
1 JOY L. REMPE, Member 2
CHARLES H. BROWN, JR. Member 3
DENNIS BLEY, Member 4
MICHAEL L. CORRADINI, Member 5
VESNA B. DIMITRIJEVIC, Member 6
WALTER L. KIRCHNER, Member 7
JOSE MARCH-LEUBA, Member 8
PETER RICCARDELLA, Member 9
GORDON R. SKILLMAN, Member 10 MATTHEW SUNSERI, Member 11 12 ACRS CONSULTANT:
13 STEPHEN SCHULTZ 14 15 DESIGNATED FEDERAL OFFICIAL:
16 CHRISTOPHER BROWN 17 MICHAEL SNODDERLY 18 19 20 21 22 23 24 25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.
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3 ALSO PRESENT:
1 CLINTON ASHLEY, NRO 2
PETER BAMFORD, NRR 3
TOM BERGMAN, NuScale 4
KEVIN COYNE, NRO 5
NADJA JOERGENSEN, NuScale 7
REBECCA KARAS, NRO 8
CHRIS MAXWELL, NuScale 9
RYAN NOLAN, NRO 10 OMID TABATABAI, NRO 11 DINESH TANEJA, NRR 12 ANDREA VEIL, ACRS 13 ROBERT VETTORI, NRO 14 SCOTT WEBER, NuScale*
15 ROBERT WEISMAN, OGC 16 17
- Present via telephone 18 19 20 21 22 23 24 25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.
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4 A G E N D A 1
Opening Remarks.................
5 2
Overview of Chapter 20, "Mitigating Strategies 3
for Beyond Design-Basis External Events,"
4 NuScale Design Certification Application 5
NuScale..................
9 6
NRO Staff................. 76 7
Public Comments................
135 8
Discussion 141 9
Adjourn....................
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5 P R O C E E D I N G S 1
1:05 p.m.
2 CHAIR REMPE: This meeting will now come 3
to order. This is a meeting of the Advisory Committee 4
on Reactor Safeguards NuScale Subcommittee. I'm Joy 5
Rempe, Chair of the NuScale Subcommittee.
6 Members in attendance today include Vesna 7
Dimitrijevic, Dennis Bley, Jose March-Leuba, Charlie 8
- Brown, Walt
- Kirchner, Pete Riccardella, Mike 9
Corradini, Dick Skillman. We also have our 10 consultant, Steven Schultz here with us today.
11 The purpose of today's meeting is for the 12 Subcommittee to receive a
briefing on staff 13 evaluations of Chapter 20, mitigating strategies for 14 beyond design basis external events in the NuScale 15 design certification application. Today, we have 16 members of the staff and NuScale to brief the 17 Subcommittee.
18 Before I continue with our standard ACRS 19 subcommittee opening remarks, I want to make some 20 comments here. The ACRS review of this topic's going 21 to be a bit different than we originally planned. A 22 couple of weeks ago, NuScale notified our designated 23 federal officials that they'd like to present this 24 material at the July full committee meeting.
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6 And the DFOs checked with the staff, and 1
they'll also be presenting tomorrow. So there's the 2
potential that we may complete our review of this 3
topic and write a letter this week.
4 And in fact, I have prepared a very draft 5
letter with some background information regarding this 6
topic, essentially what topics are addressed by 7
NuScale in the Chapter 20. And how their strategies 8
for beyond design basis events differ from other 9
applications we reviewed and the staff review 10 findings, and some preliminary thoughts that we may 11 want to discuss today. But I'm going to need your 12 help on this.
13 So at the end of this meeting, I'd like to 14 request your thoughts on two items. First, shall we 15 try and write a letter on this topic this month? And 16 we can recommend and at the beginning of the full 17 committee meeting that the letter would be completed 18 in September.
19 And then if we do decide to go forward 20 with the letter this month or even in September, I'd 21 like your input for my draft letter on what should be 22 included in this topic. And it would help if you'd 23 send it tonight sometime, okay.
24 So let's go back to the standard 25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.
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7 information that I'm supposed to say at the beginning 1
of Subcommittee meetings. The ACRS was established by 2
statute and it's governed by the Federal Advisory 3
Committee Act, or FACA. That means that the committee 4
can only speak through its published letter reports.
5 And we hold meetings to gather information to support 6
our deliberations.
7 Interested parties who wish to provide 8
comments can contact our office requesting time. And 9
that said, we also set aside ten minutes for comments 10 from members of the public attending or listening to 11 our meetings. And written comments are also welcome.
12 The meeting agenda for today was published on the 13 NRC's public meeting notice website, as well as our 14 ACRS meeting website.
15 And on the agenda for this meeting, as 16 well as on the meeting, the ACRS website, instructions 17 on how the public can participate. It's my 18 understanding, unless Kathy tells me differently, that 19 there's been no requests for making a public statement 20 from the public at this meeting.
21 And we may close this meeting after the 22 open portion to discuss proprietary material, and 23 presenters can defer questions that should not be 24 answered in the public session to that time. And if 25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.
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8 we start asking things we shouldn't, please speak up 1
and tell us to hold off, okay.
2 A transcript of the meeting is being kept 3
and will be made available on our website. And 4
therefore we do request that participants in this 5
meeting use the microphones located throughout the 6
meeting room in addressing the Subcommittee, and the 7
participants should first identify themselves and 8
speak with sufficient clarity and volume that they can 9
be readily heard.
10 We have a bridge line established for the 11 public to listen to this meeting, and to minimize 12 disturbance, the public line will be kept in a listen-13 in only mode. And to avoid disturbance, I request 14 that attendees, especially
- members, put their 15 electronic devices, such as cellphones, in the off or 16 noise-free mode.
17 And now we're going to begin with the 18 meeting. Does the NRC staff have any introductory 19 remarks that they wish to make?
20 MR. COYNE: Kevin Coyne, NRO. We can make 21 it just part of the staff presentation after the 22 break.
23 CHAIR REMPE: Okay, so then I'm going to 24 ask NuScale to begin today's presentations.
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9 MS. JOERGENSEN: Thank you. We're here 1
today to present NuScale SR Chapter 20, which is the 2
mitigation of beyond design basis events. With me 3
here I have Chris Maxwell, Senior Reactor Operator, 4
and myself, Nadja Joergensen. I'm a Licensing 5
Specialist.
6 MR. MAXWELL: Good afternoon. The new 7
rule, 10 CFR 50.155, is separated into a requirements 8
section for mitigational strategies for beyond design 9
basis external events, which is covered under 10 paragraph B1, and into requirements specific for spent 11 fuel pool level indication, which is addressed by 12 paragraph E. And we're going to start today's 13 discussion with the mitigation strategies.
14 The new rule is written to consider a 15 damaged state that results in an extended loss of AC 16 power and ELAP concurrent with a loss of normal access 17 to the ultimate heat sink, or for a passive design 18 such as NuScale's, a loss of normal access to the 19 normal heat sink.
20 The objective of the rule is to establish 21 sufficient coping capabilities to prevent fuel damage 22 in both the reactors and the spent fuel pool, and to 23 maintain the containment function by using installed 24 plant equipment and supplemental mitigating equipment.
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10 As such, the three key safety functions of 1
core cooling, containment, and spent fuel pool cooling 2
are required to be established and maintained 3
indefinitely, or until sufficient site functional 4
capabilities can be maintained without the need for 5
mitigational strategies.
6 That phrase indefinitely or until 7
sufficient site functional capabilities can be 8
maintained without the need for mitigation strategies 9
is described to mean that the licensee needs to plan 10 for obtaining sufficient resources to maintain the 11 three key safety functions until an alternate means of 12 heat removal is established.
13 Additionally, the new rule allows for new 14 reactors to establish different approaches from those 15 of operating reactors, including using only installed 16 plant equipment for both the initial and the long-term 17 response. Therefore it follows that the phrase 18 alternate means of removing heat may be provided by 19 installed plant equipment.
20 To evaluate the NuScale power plant coping 21 capability, it's necessary to establish what a minimum 22 installed coping duration is. NuScale considers a 23 coping period of 14 days using only installed plant 24 equipment to be sufficient time to establish the 25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.
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11 alternate means of removing heat.
1 The basis for this duration is the 2
operating experience of the Fukushima event, where, 3
without the benefit of a pre-planned strategy or a 4
hardened pool makeup line, the access to the site 5
limited by the earthquake and tsunami, personnel were 6
able to begin injecting to the spent fuel pool after 7
nine days using offsite resources and injecting the 8
spent fuel pool using installed plant equipment at 14 9
days.
10 Beyond that point, beyond the minimum 11 installed equipment coping period, the continued use 12 of installed plant equipment, as well as ad hoc 13 resources and repairs to plant equipment, can be used 14 to continue coping indefinitely.
15 MEMBER BLEY: Can I ask you a question?
16 MR. MAXWELL: Yes, sir.
17 MEMBER BLEY: Much of the arguments I've 18 read in the FSAR show how your built-in capabilities 19 are adequate for most of these requirements. So it 20 doesn't look like you're recommending to a future COL 21 applicant that they participate in SAFER because it 22 doesn't sound like you think it'd be necessary.
23 Are you providing those standard hook-ups 24 that say for uses, so if you need to get equipment 25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.
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12 from, you might get it from another nearby plant, so 1
it would be easy to hook it up?
2 MR. MAXWELL: Yes, sir, we are. What we 3
have, beyond what we'll be talking about today, we 4
have the standard equipment you would see as far as we 5
backup diesel generators, two of them independent from 6
one another that can provide power to our battery 7
chargers and our highly reliable DC power system and 8
to our instrumentation.
9 We have temporary or temporary connections 10 to those same busses provided by the diesel generators 11 for an offsite generator that's --
12 MEMBER BLEY: And that's the connections 13 I was asking about. Are they going to be the standard 14 ones that are --
15 MR. MAXWELL: Yeah, they're --
16 MEMBER BLEY: All the other plants are 17 using now?
18 MR. MAXWELL: That's correct. We can 19 bring a portable, the design includes connections for 20 portable generators.
21 MEMBER BLEY: Okay.
22 MR. MAXWELL: It also includes a hardened 23 vent, seismically qualified, assured makeup line to 24 the ultimate heat sink for, a gravity feed to the 25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.
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13 spent fuel pool. While all those capabilities are 1
provided to meet the requirements, they're not 2
required.
3 MR. SCHULTZ: So excuse me, so what does 4
that mean in terms of what Dr. Bley was discussing in 5
terms of the guidance that you anticipate providing to 6
the COL applicant?
7 MR. MAXWELL: Well, there's -- the COL and 8
the operator are going to have requirements to perform 9
task analysis on their systems and develop procedures 10 associated with it. There won't be a requirement 11 specifically for procedures for mitigating beyond 12 design basis event, because no operator actions are 13 required specifically to mitigate the event.
14 You still, you know, I like to think of 15 this as two separate items. There is the responding 16 to the event itself, the ELAP and the current loss of 17 access to the ultimate, to the normal heat sink, and 18 the plant response to that through installed safety-19 related plant equipment.
20 Then there's what the operators are going 21 to be doing. And the benefit of the plant responding 22 to the strategy or to the event and maintaining the 23 three key safety functions is that the operators have 24 been freed up to use the exiting procedures to try to 25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.
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14 restart their backup diesel generators or to hook up 1
a temporary generator if necessary to respond to the 2
initiating event itself, rather than to be focused on 3
establishing and maintaining the three key safety 4
functions.
5 So they will use their processes as 6
required for operations to develop their procedures 7
for hooking up that equipment and repowering the 8
busses. Items like starting the backup diesel 9
generators is not unique to mitigating a beyond design 10 basis event. It's a procedure that will exist, a 11 standard operating procedure or an abnormal procedure 12 that will exist for the plant that it would use in the 13 situation.
14 MR. SCHULTZ: But let's presume that there 15 is a fleet of these facilities. Then you would 16 anticipate that there'd be some common direction given 17 so that the fleet of NuScale facilities are going to 18 be following the same process and procedure. And if 19 there is, if there is a safer type of an approach, or 20 a common approach taken, that in fact it is a common 21 approach.
22 MR. MAXWELL: Yes, sir, and --
23 MR. SCHULTZ: For the NuScale industry, 24 whatever you want to call that.
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15 MR. MAXWELL: Right, and again, I'm back 1
to the separation of whatever the initiating event is, 2
it's a loss of all power, all AC power, they're safe.
3 There will be a procedure to respond to the loss of 4
all AC power. So it's not specific to a mitigating 5
beyond design basis event, it's specific to the 6
initiator.
7 So there will be a procedure that is an 8
abnormal procedure to respond to that that directs the 9
action, such as starting up backup diesel generators 10 or getting our auxiliary AC power source available to 11 provide site power.
12 If it's a seismic event, there'll be an 13 abnormal procedure to respond to seismic events. If 14 it's flooding, you would expect a abnormal procedure 15 to respond to a flooding event. So again, the 16 operators are freed up to address those initiating 17 events and respond to them and to restore power, 18 rather than to focus on the key safety functions.
19 And there's not a need for specific 20 procedures dedicated to that. There's not a, in the 21 days of old were called FLEX procedures. There's not 22 a need for that because the installed plant equipment 23 responds to establish and maintain the three key 24 safety functions.
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16 MR. SCHULTZ: Okay, thank you.
1 MR. MAXWELL: Sure. So now I'd like to 2
discuss the evaluation of the NuScale design coping 3
capability and to describe those capabilities.
4 As you're aware, the NuScale power plant 5
design was informed by the Fukushima accident and 6
sought to provide coping during an ELAP without AC or 7
DC electrical power, without a need for inventory 8
addition or supplemental onside equipment, without the 9
use of offsite resources, and without any operator 10 actions and therefore any required operator 11 monitoring.
12 In short, the design provides extended 13 coping by establishing and maintaining three key 14 safety functions by the automatic response of 15 installed plant equipment alone. As I just alluded 16 to, the strategy provides a significant advantage of 17 permitting the plant staff to focus on addressing the 18 initiating events, rather than focusing on deploying 19 supplemental equipment or procedures, to maintain just 20 the three key safety functions.
21 To evaluate the power plant's baseline 22 coping capability, it's necessary to establish some 23 coping criteria as well as the initial conditions, 24 assumptions, and the boundary conditions. For this, 25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.
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17 NuScale used existing industry guidance as previously 1
endorsed by the NRC.
2 And they include that plant equipment that 3
is designed to be robust with respect to design basis 4
external events is assumed to be fully available, 5
while plant equipment that's not robust is assumed to 6
be unavailable.
7 The procedures and equipment relied upon 8
should ensure the satisfactory performance of 9
necessary fuel cooling and containment functions are 10 maintained and that the fuel in, both the modules and 11 the spent fuel pool is required to remain covered at 12 all times.
13 CHAIR REMPE: So I'd like to stop you for 14 a minute. You keep referring to the insights from 15 Daiichi. And if you read some of the operator 16 interviews, they make the comment because they didn't 17 have instrumentation due to the loss of power, it was 18 like flying an airplane blind.
19 And now you're talking about monitoring 20 the plant, that things are going as planned, and you 21 actually have in Rev. 1 of this technical report you 22 submitted saying that the ECCS components, including 23 instrumentation, are environmentally qualified for the 24 moisture chemistry and radioactivity of expected 25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.
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18 environments, and it goes on about that.
1 And if I look at the table you provided, 2
you do have the water level, so I have a question 3
about the radioactivity levels. Are you going to do 4
fluence? Again, we, and I can say radar-based water 5
levels since they're here because we've established 6
now that's in the open literature. But I'm not sure 7
of the details of it.
8 But some of them actually if you have some 9
types of monitors, they tried to do this in the past, 10 they suffer from darkening from fluence levels. And 11 I'm not sure if that's going to be in your design or 12 not, but that's something I'm concerned about.
13 And then if I were an operator I'd, since 14 you're kind of putting the water back and forth 15 between the reactor vessel and the containment, I 16 really would like to know what the containment water 17 level is to make sure things are going as planned, and 18 that's not one of the key components that's in the 19 table about the containment. You just have other 20 components in the containment.
21 So I'm curious on why you didn't include 22 the containment water level too as a key component.
23 Because I think I would want to know as much as 24 possible of what's going on, especially if you had 25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.
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19 some sort of event where you went back and got re-1 critical again and you're going to flood up your 2
containment. It seems like that.
3 So I have questions about why didn't you 4
include the water level for the containment, and then 5
the radioactivity levels and how you're going to 6
qualify it. Because again, this is kind of going out 7
to the future, and it's going to be I guess an ITAAC 8
or something about this first of a kind application 9
for water level measurements.
10 And I want to know if it's going to be 11 looking at not just the heat, the neutron flux, but 12 also the total fluence. Are you going to go for, 13 sometimes I see 30 days or something like that? Or 14 how long are you going to qualify this for, and is 15 that going to be specified somewhere?
16 MR. MAXWELL: I'll ask if Brian Gardes is 17 on the line from NuScale. I don't have Brian now, but 18 I will.
19 CHAIR REMPE: They were supposed to be 20 open, but.
21 MEMBER CORRADINI: Can the NuScale folks 22 in Corvalis speak up that your line's open?
23 (Off mic comments.)
24 MR. MAXWELL: Okay, thank you. So as, 25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.
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20 we're going to see if Brian can speak to the level 1
instrument specifically. The discussions on the 2
technical report about instrumentation are just some 3
discussions of the instrumentations that would be 4
available to the operators. Containment level will be 5
available for 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br /> to the operators.
6 CHAIR REMPE: It's not in the list of the 7
critical, like there's a table it's going to take me 8
a while to bring it up. But there's a table for 9
what's in the reactor vessel versus what's in the 10 containment. And the containment does not have water 11 level on that table.
12 MR. MAXWELL: Understood, and so what I 13 want to say is that none of those indications are 14 necessary, because installed plant equipment alone, 15 without operator action, without operator monitoring, 16 establishes and maintains the three key safety 17 functions.
18 MEMBER MARCH-LEUBA: ECCS valves open on 19 high water level in the containment.
20 MR. MAXWELL: Not in this event they do 21 not.
22 MEMBER MARCH-LEUBA: Well, then you have 23 to consider, this is available.
24 MR. MAXWELL: ECCS at 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> in this 25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.
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21 event, the next slide here talks about our boundary 1
conditions. For an ELAP condition, there's a box 2
that's established and some assumptions that are made 3
about the plant response.
4 MEMBER MARCH-LEUBA: But to be able to say 5
with a straight face that you do not rely on AC or DC 6
power, you have to run every combination of AC power 7
on, AC power off, the other way around, DC power going 8
to five holes. You have to run all those 9
combinations.
10 MR. MAXWELL: Absolutely.
11 MEMBER MARCH-LEUBA: And you're relying on 12 DC power to open the ECCS valves.
13 MR. MAXWELL: In 20 -- actually, the 14 module protection system in this event, at 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> 15 into the event, de-energizes the --
16 (Simultaneous speaking.)
17 MEMBER MARCH-LEUBA: If you lose AC power.
18 MR. MAXWELL: This event is a loss of AC 19 power.
20 MEMBER MARCH-LEUBA: You rely, for 21 successful completion, you are relying on losing AC 22 power. What if you keep --
23 MR. MAXWELL: I keep AC power?
24 MEMBER MARCH-LEUBA: Yeah.
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22 MR. MAXWELL: The event is a loss of AC 1
power. It is the defining --
2 MEMBER CORRADINI: Yeah, I think what, I 3
want to make sure you guys are communicating. I think 4
what Chris is saying is they have a set of going in 5
state assumptions that they have to follow. Am I 6
understanding this correctly?
7 MR. MAXWELL: Yes, sir, that's exactly 8
correct. The event itself is defined as an extended 9
loss of AC power concurrent with loss of normal access 10 to the normal heat sink.
11 And then there's a set of boundary 12 conditions that were established, again, established 13 in industry guidance and endorsed by the NRC, that are 14 the baseline assumptions. Then you start your 15 evaluation of our coping capability with those 16 assumptions.
17 CHAIR REMPE: So I'm going to go back to 18 Section 5.3.2, and it has here, The key safety 19 function of containments is established and maintained 20 for greater than 50 days without operator action.
21 However, the parameters listed in table 5.2 or 5-2, 22 are available to assure the control room operators 23 that the safety-related systems have performed as 24 designed.
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23 And it has the CIV positions and the wide 1
range containment pressure and the spent fuel pool 2
level. There is nothing in here about containment 3
water level.
4 MR. MAXWELL: I understand that, and what 5
I'm trying to convey is none of those indications are 6
necessary to establish and maintain. However, just 7
for the containment, just addressing the containment 8
function, containment water level is not a key 9
parameter.
10 When that list was developed, it said if 11 I'm just looking at of the three key safety functions, 12 if I'm just evaluating the containment function, what 13 I need to know is a containment pressure. If I'm an 14 operator and I'm, which of course this is not going to 15 happen that the operators just sit back and observe.
16 But if that's what they were doing, then 17 what they would have observed is at the 24-hour mark, 18 when the ECCS valves open, that's when you would reach 19 the peak pressure in containment. So containment 20 pressure is one aspect of containment integrity that 21 they would want to monitor.
22 Early within the first minute, there's a 23 containment isolation. So containment isolation valve 24 position is a key parameter for them to verify that 25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.
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24 the safety-related components have performed as 1
designed.
2 CHAIR REMPE: So your point is just that 3
you don't worry about overpressure of the containment, 4
but if I were also trying to worry about the reactor 5
going re-critical, that's not a concern. It's just, 6
okay, you've still got the water level in the reactor 7
vessel and yeah, something's going on with the water 8
going back and forth, but you're not going to worry 9
about trying to flood up the containment or something 10 like that if the reactor --
11 MR. MAXWELL: We will not flood up the 12 containment. Within the boundaries of this event, the 13 containment isolates, all safety-related components 14 operate as designed. There's, of the inventory 15 necessary to maintain core cooling is preserved within 16 the containment.
17 CHAIR REMPE: And you don't worry about 18 any sort of re-criticality occurring for this event.
19 But what if it did occur, you just, that's not part of 20 the scope and you don't have to worry about it.
21 MR. MAXWELL: That's right, the boundary 22 conditions, one of the boundary conditions is that 23 there's no current ATWS, no anticipated transient 24 without scram. All rods insert.
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25 CHAIR REMPE: Okay.
1 MEMBER MARCH-LEUBA: A single rod fails?
2 MR. MAXWELL: That's correct. But you 3
remember the scope here, we're talking about a beyond 4
design basis event. So we're in a, like other events 5
where you're not required to stack failures, like a 6
control room evacuation doesn't assume a concurrent 7
LOCA or an ATWS. Similarly, and in the operating 8
fleet and our assumptions is that there isn't a 9
concurrent ATWS with the extended loss of AC power.
10 MEMBER MARCH-LEUBA: It's not an ATWS, 11 it's one rod has too much friction can come in after 12 the earthquake.
13 MR. MAXWELL: We assume all rods insert in 14 this event. The assumption of boundary condition.
15 MEMBER MARCH-LEUBA: Yeah, and I can 16 assume, you can assume a lot of things.
17 MEMBER CORRADINI: But I think what, I'm 18 not taking sides, I just want to make sure we're 19 communicating. Is that they're been given a set of 20 assumed, going in statuses of the various systems, 21 which they then must analyze. Am I understanding this 22 correctly?
23 MR. MAXWELL: Yes, sir.
24 MEMBER RICCARDELLA: And are those the 25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.
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26 same assumptions that the operating fleet uses?
1 MR. MAXWELL: Yeah. We extracted these 2
directly from the existing fleet guidance.
3 CHAIR REMPE: So I'll give you that one 4
for a while I guess. But then what about the fact 5
here for the core cooling parameters when they have 50 6
days and they have the table, the parameters in table 7
5-1, and they have water level as a parameter here?
8 So somehow or other you're going to give 9
us confidence that you don't have any sort of issues 10 for the entire fluence, not just at the radiation 11 levels, as it indicated in the other quote I read 12 earlier. But you're going to also do the fluence on 13 the RPV water level sensors to make sure they're 14 qualified?
15 MR. MAXWELL: I believe I don't have that 16 table in front of me, but if you look, I believe it's 17 broken into two sections, and the first is the 18 verification portion, where the instruments that are 19 used to verify that those conditions have been 20 established.
21 And then the extended duration, what 22 indication the operators could use to verify that the 23 key safety function core cooling is maintained. I'd 24 also say that that's an old revision of the technical 25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.
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27 report as well.
1 CHAIR REMPE: I'm actually looking at Rev.
2 1 and there isn't this, it only has parameters for 3
assuring the functions established and the function.
4 So there's just two columns in the table I'm looking 5
at. Do I need to go back to Rev. 0 to see what you're 6
talking?
7 MR. MAXWELL: No, that serves the same 8
purpose. As far as establishing the function, if I 9
heard you correctly, that that's the header for that 10 column, is that when the function is established, the 11 instrumentation exists. Or the power for the 12 instrumentation's assured.
13 CHAIR REMPE: But this has to be for 50 14 days, according to the text.
15 MR. MAXWELL: It's established within 24 16 hours1.851852e-4 days <br />0.00444 hours <br />2.645503e-5 weeks <br />6.088e-6 months <br />. The Emergency Core Cooling System actuation at 17 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> is the last action, automatic action that 18 occurs during this event. Operators can observe the 19 actuation of ECCS, and with ECCS in service, the 20 natural circulation provided, then that safety 21 function is assured for 50 days.
22 CHAIR REMPE: Well, the introductory 23 sentence says, The key safety function for coolant is 24 established and maintained for greater than 50 days 25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.
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28 without operator action. And so you're trying to tell 1
me then that they only need it for the 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br />, not 2
the full 50 days.
3 MR. MAXWELL: The indication, that's 4
correct. Once the ECCS valves open, there's no 5
plausible mechanism for those valves to reposition 6
closed. They're in their safety position, the natural 7
circulation's established.
The containment's 8
isolated, so the inventory is contained within the 9
containment vessel.
10 And operators observe the operation of 11 ECCS. Their continued observance isn't required to 12 assure that the system continues to function.
13 CHAIR REMPE: So okay, we don't have any 14 water level in the containment, we just have it in the 15 reactor vessel. But we're just going to, the 16 operators will say, okay, the valve opened and I don't 17 care anymore for 50 days, I don't need any 18 instrumentation is the position you're taking?
19 MR. MAXWELL: I would only characterize 20 that the operators don't care anymore. I would say 21 that when the safety systems actuate and are in 22
- service, then within the boundary conditions 23 established event, that the safety function is 24 maintained for a minimum of 50 days.
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29 CHAIR REMPE: I just, as a, I think an 1
operator would want to know what's going on through 2
that 50 days is especially after, again, I know it was 3
a big BWR, but knowing how an operator feels when they 4
don't have any instrumentation, I think you would want 5
to have confidence that it would last.
6 MEMBER BROWN: But the loss of ultimate 7
heat sink is not, you all stated in your Chapter 20 8
that that's not plausible, therefore that's really not 9
part of this particular evaluation that you all are 10 doing. The only thing that plays here is the 11 extended loss of AC power.
12 MR. MAXWELL: The actual, it's a loss of 13 access to the ultimate heat sink that the --
14 MEMBER BROWN: Well, but you're sitting in 15 the ultimate==
16 MR. MAXWELL: That's right.
17 MEMBER BROWN: You're sitting in the 18 ultimate heat sink. So you haven't, theoretically you 19 can't lose access, and you say that. There is no, the 20 loss of it as defined in the reference is not 21 plausible, no other heat sink is credited for 22 maintaining the key safety functions. So I'm just 23 trying to separate the variables here.
24 MR. MAXWELL: Right.
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30 MEMBER BROWN: We keep arguing about this 1
and these two primary initiating conditions. One of 2
them is not relevant for this because you're always 3
sitting in the ultimate heat sink. The only thing 4
that plays is the extended loss of AC power, and that 5
plays into whatever other things have to happen, the 6
valves closing and all the other type things that 7
you're talking about.
8 MR. MAXWELL: That's correct, and for the 9
passive designs, they defined it as an extended loss 10 of AC power with loss of normal access to the normal 11 heat sink. So we don't have the main condensers 12 available.
13 MEMBER BROWN: Your normal sink's the pool 14 of the water, isn't it?
15 MR. MAXWELL: No, sir, normally it's the 16 main condenser.
17 MEMBER SKILLMAN: It's no steam dump. No 18 steam dump.
19 MEMBER RICCARDELLA: Or load. So that's 20 their normal.
21 MEMBER BROWN: I've never thought of that 22 as the heat sink because you're sitting in the thing, 23 and.
24 MEMBER BLEY: Yeah, but that's where the 25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.
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31 heat's going.
1 PARTICIPANT: But only --
2 MEMBER BROWN: Well, the containment's 3
not, is still evacuated in this circumstance, isn't 4
it?
5 MR. MAXWELL: It is until 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> into 6
the event. At 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> into the event, it's when the 7
ports open.
8 MEMBER BROWN: Okay, all right, I got 9
that.
10 MEMBER RICCARDELLA: What happens at 24 11 hours1.273148e-4 days <br />0.00306 hours <br />1.818783e-5 weeks <br />4.1855e-6 months <br /> in?
12 MR. MAXWELL: At 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br />, the module 13 protection system de-energizes the trip solenoids for 14 the emergency core cooling system, allows those valves 15 to open, and initiates ECCS.
16 MEMBER RICCARDELLA: And that floats to 17 containment.
18 MR. MAXWELL: It's DC powered.
19 MEMBER RICCARDELLA: So, oh, you're on DC, 20 okay, got it.
21 MEMBER CORRADINI: Just if we all wait two 22 slides, he has a time window that I think will help 23 us.
24 MEMBER BROWN: Well, I guess what I was 25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.
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32 getting confused with, Mike, was the loss of the 1
ultimate heat sink. The point is the containment is 2
evacuated initially for the 24 hour2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> period before it's 3
flooded, and then becomes now you have access, you 4
have access to the heat sink back effectively, once 5
you've flooded it into 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br />, correct?
6 MEMBER MARCH-LEUBA:
So you have 7
additional access. You always have the DHRS.
8 MR. MAXWELL: That's right.
9 MEMBER MARCH-LEUBA: And just satisfy on 10 the record, the special with the level, whether the 11 ECCS valves open or they don't, you will still survive 12 the event perfectly. Actually, if you don't lose DC 13 power, the event will be even better than you describe 14 here, because you will have the DHRS cooling your 15 decay heat nicely.
16 Opening the ECCS valves is just an 17 additional step to have is because you lost DC power.
18 But you would, it would be a success branch if you 19 kept the DC power on. Outsourced.
20 MR. MAXWELL: It is a, we load-shed the 21 ECCS solenoids off of the batteries at 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> --
22 MEMBER MARCH-LEUBA: I understand. But if 23 you lost all AC power except the one that fuels the 24 batteries, nothing bad will happen in this event. You 25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.
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33 could run that one and it would be a success. But, 1
because you will keep cooling on DHRS high pressure.
2 MEMBER KIRCHNER: He's saying the DHRS 3
system would successfully take you to a safe --
4 MR. MAXWELL: It's complicated because the 5
power that powers the chargers is the same power, so 6
the logic --
7 MEMBER MARCH-LEUBA: Yeah, but if you 8
claim that you'll rely on it --
9 MR. MAXWELL: Right.
10 MEMBER MARCH-LEUBA: The rule is, I don't 11 know what rule is for Mike, but for me is you can live 12 with it or without it.
13 MR. MAXWELL: Absolutely.
14 MEMBER MARCH-LEUBA: If we have every 15 possible combination. And indeed, you do.
16 MR. MAXWELL: If we had AC power available 17 on busses, it would not impact this event in a 18 negative way, negative manner. We would still have 19 all of our safety-related systems, module protection 20 system, the containment isolation system, reactor trip 21 system, and DHRS actuation.
22 MEMBER MARCH-LEUBA: What I'm trying to 23 say is you do not rely on ECCS actuating 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> 24 before the successful operation.
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34 MR. MAXWELL: We do not, that's correct.
1 MEMBER MARCH-LEUBA: If they kept close, 2
you would still survive perfectly.
3 MR. MAXWELL: We still have DHRS that 4
provides the core cooling initially.
5 MEMBER MARCH-LEUBA: It's redundant and 6
sufficiently -- so our discussion about the ECCS 7
actuation in this particular transient.
8 MEMBER DIMITRIJEVIC: For how long can 9
DHRS operate for, you know? How long can DHS remove 10 the heat successfully?
11 MR. MAXWELL: I have to, I don't know the 12 answer to that question off the top of my head.
13 MEMBER MARCH-LEUBA: DHRS has a capacity 14 of roughly six percent power?
15 MEMBER DIMITRIJEVIC: I know, but you need 16 the, you know, the nature of its inflation and all.
17 MEMBER CORRADINI: Under this stylized 18 accident, though, they have a slide later to show --
19 MEMBER SKILLMAN: It shows it, it's coming 20 up.
21 MEMBER DIMITRIJEVIC: My other question is 22 for your ultimate heat sink you need eventually 23 outside cooling, right. What provided, what provides 24 the cooling for your pool? No, no, no, but that pool 25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.
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35 needs to be cooler.
1 MR. MAXWELL: We don't, no boiling, 2
boiling of the ultimate heat sink provides the 3
sufficient cooling for the modules. It eventually, 4
and we have slides that will show this. But 5
eventually we would add inventory, maintain inventory.
6 But --
7 (Simultaneous speaking.)
8 MR. MAXWELL: -- temperature control.
9 MEMBER BROWN: To the reactor pool.
10 MR. MAXWELL: That's correct. Ultimate 11 heat sink.
12 MEMBER DIMITRIJEVIC: Well, okay, so you 13 eventually, and what's that eventually when you need 14 to provide inventory to the ultimate heat sink?
15 MR. MAXWELL: Our analysis, we talk about 16 with 50 days, is based on 45 feet, a 45-foot elevation 17 in the pool. And that's just where the long-term 18 cooling calculation evaluation stopped, at 45 feet.
19 It didn't, it's not because there's a --
20 MEMBER DIMITRIJEVIC: Twelve units put in 21 decay heat, right?
22 MR. MAXWELL: With all 12 units, right.
23 We didn't evaluate beyond that point, so it's not 24 significant in that something happens in the ability 25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.
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36 to cool core, to remove containment heat. It's just 1
that we went out to 45 feet, and that's where the 2
calculation stopped.
3 MEMBER MARCH-LEUBA: Those units, were the 4
DHRS, what elevation is DHRS?
5 MR. MAXWELL: The top of the DHRS passive 6
condenser is just above 45 feet.
7 MEMBER MARCH-LEUBA: Top 45 feet is the 8
DHRS.
9 MR. MAXWELL: It's 45 feet just below the 10 top of the passive condenser.
11 MEMBER MARCH-LEUBA: It will work another 12 foot.
13 MR. MAXWELL: Still mostly submerged.
14 MEMBER SKILLMAN: Chris, may I ask you to 15 go back one slide please?
16 MR. MAXWELL: Yes, sir. Figure out how, 17 yeah, thank you.
18 MEMBER SKILLMAN: Thank you. Let's see, 19 operator action monitoring. Would you speak more to 20 that please?
21 MR. MAXWELL: Again, just to --
22 MEMBER SKILLMAN: This is without AC or 23 DC. Go ahead.
24 MR. MAXWELL: Yes, sir, just within the 25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.
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37 confines of the scope of this event, the, with the 1
design relying only on --
2 MEMBER SKILLMAN: Oh, these are the game 3
rules for the way this rolls out.
4 MR. MAXWELL: That's correct.
5 MEMBER SKILLMAN: Okay, go ahead.
6 MR. MAXWELL: With that, because it's the 7
automatic response of the installed plant equipment 8
that establishes and maintains the key safety 9
functions, no operator actions are necessary to do so.
10 With the need for monitoring is predicated on the need 11 for operator action. If I don't have any required 12 operator action, then I don't have a requirement for 13 monitoring.
14 As an operator myself, of course I want 15 to, I'm going to monitor, I'm going to, you know, 16 observe the actuation of all the safety-related 17 equipment. But back inside those boundary conditions, 18 that safety-related equipment performs as designed.
19 So that's the discussion about with no operator 20 action, therefore no monitoring's required.
21 MEMBER SKILLMAN: And I don't want to be 22 preachy, but just let me make a point or two. I can 23 buy and defend loss of AC and DC. I can defend no 24 inventory. I can defend no supplemental equipment.
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38 I can defend no operator resources. I cannot defend 1
a responsible SRO in charge of the watch for 12 plants 2
not fighting to the death for at least source range 3
instrumentation.
4 And I base that having been involved in an 5
NBDE like this. The thing we wanted more than 6
anything else at TMI2 was primary instrumentation for 7
neutron count. And we had several instances where we 8
lost it. And there was more excitement, and what I 9
mean by that is the emotion of fright, than anything 10 else.
11 We began to understand we didn't have 12 pressurizer level. We knew the pumps were vibrating.
13 From the radiation levels we knew we had lost a lot of 14 fuel or clad. But the thing that we were driven by 15 was neutron count rate. I would think that maybe that 16 one issue should be revisited.
17 If you were in charge of 12 reactors and 18 you've had this event, I think the one thing you would 19 be saying is I know a shutdown, I'm fairly confident 20 it's, I'm fairly confident it's shut down. And I 21 really think it's shut down, but I would really like 22 to have something that confirms it's shut down, 12 23 times.
24 So I would just offer I think that's a 25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.
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39 blind spot that NuScale should think about, for a lot 1
of reasons. I mean, this whole design is predicated 2
on the robustness of the passive competencies to 3
protect the cores.
4 But the one parameter that seals the deal 5
in the operator's mind and in the NRC inspector's mind 6
is that we've got a count rate that we believe is 7
accurate. And the neutron count rate has dropped and 8
is not increasing.
9 Thank you for the monologue.
10 MEMBER BLEY: I was, just before you did 11 that, Dick, I wanted to go back to where Joy was. And 12 I just wanted to urge you to think about this, because 13 you are an operator. I mean, you meet the 14 requirements, I don't disagree with that. The 15 analysis looks right. But if you're an operator and 16 you can't see what's going on, and there's lots of 17 examples where this has happened.
18 It's not just Fukushima and TMI. There's 19 lots of other examples. When operators can't see 20 what's going on, they get nervous. They start trying 21 to find ways to see what's going on, and they operate, 22 right. They do, you don't, you know somebody did an 23 analysis and it said you're okay. But am I really 24 okay? I should be okay, am I really okay.
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40 And the idea that with a little pre-1 planning you could see some of the parameters that are 2
crucial to keeping you from doing wrong. Now, the 3
chapter on human factors engineering says we look at 4
errors of commission. The PRA says we look at errors 5
of commission, but you hardly looked at errors of 6
commission at all.
7 So what are the bad things somebody could 8
do if you get in this spot and they get nervous, and 9
they start wanting to do something? That didn't show 10 up in the PRA, it probably should have. So just to 11 think about, not that there's anything wrong with this 12 analysis for this purpose. I'm done.
13 MR. BERGMAN: Can I just say what I did--
14 PARTICIPANT: Are you going to identify 15 yourself?
16 MR. BERGMAN: Yeah, Tom Bergman.
17 PARTICIPANT: Get close to the mic.
18 MR. BERGMAN: Tom Bergman, NuScale. So I 19 appreciate what you said, yes. The purpose of our 20 application and the purpose of this presentation is to 21 demonstrate that we meet the NRC's regulation. It 22 isn't to say what we or operators will do that goes 23 beyond that regulation. So of course our operators 24 care, of course they will try to maintain as many 25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.
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41 instruments as they can.
1 But in terms of this regulation, thank you 2
for noting, the question is have we met the 3
regulation. If you think the regulation isn't 4
appropriate, those questions need to go to the NRC 5
staff, because we think we've made the case we've met 6
the NRC's regulation.
7 CHAIR REMPE: Again, I, it extends beyond 8
Chapter 20. But even if you're going to do the water 9
level, I'm curious on how we're going to have it 10 qualified in the reactor vessel if you are going to 11 rely as it -- it's a key parameter they're monitoring, 12 so maybe it doesn't fall under Chapter 20, it's just 13 it's there by the way.
14 But I am not sure that the qualification 15 for the water level will consider something for those 16 conditions that are considered in Chapter 20 is what 17 I was trying to get to.
18 The other thing is is that at some point, 19 and I know you slides on it later, but saying that you 20 don't have operator action and this thing about the 21 batteries is a thing I'd like to see you discuss today 22 while you're up here too, because it does seem to 23 imply that your battery runs out after, it could run 24 out after 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br />.
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42 And so I know you're going to be 1
discussing that, but there is some action required to 2
replace a battery apparently, okay.
3 MR. MAXWELL: I will address that in spent 4
fuel pool level indication portion.
5 MEMBER BROWN: Can I ask one, this is a 6
question just to clarify for myself -- somebody 7
answering something? I'm sorry, I didn't mean to 8
interrupt.
9 CHAIR REMPE: Go ahead, speak up.
10 MR. WEBER: I just wanted to go over 11 information on -- sorry, this is Scott Weber in the 12 PRA group at NuScale. And I just wanted to add a 13 little bit of information about like containment water 14 levels from the other instruments that we've been 15 talking about.
Because we're talking very 16 specifically in the context of Chapter 20.
17 But obviously for all these dissertations, 18 anything that NuScale has determined to be a close 19 monitoring variable is also subject to equipment 20 qualification and to equipment operability 21 requirements.
22 And so just because something is not 23 necessarily on, you know, a list of the key functions 24 with specific respect to this event, that does not 25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.
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43 mean that it doesn't have equipment qualification 1
requirements, which are generally, you know, for every 2
two hours or beyond some, or up to 30 days or 100 days 3
in that table; and then you have the subpart to that, 4
which I don't have in front of me immediately.
5 But the equipment qualification program is 6
the -- subject to the same conditions that you would 7
see in the type of events where it is an extended loss 8
of power but it's not a core damage event. It's a 9
primary source for cooling activity. That's all 10 reflected in the equipment qualification program, and 11 so all these instruments are going to be shown 12 expected to be qualified.
13 And additionally there will be 14 survivability requirements that use a beyond design 15 basis core damage event. So we just want to make sure 16 that that is understood. And that's it, and if 17 there's more questions?
18 CHAIR REMPE: So the thing was is this a 19 first-of-a-kind application, and it's my understanding 20 when the water level sensors were reviewed, it was not 21 clearly stated that they're going to this first-of-a-22 kind technology. For example, if you'd used a DP 23 cell, you might not have been worried about a 24 radiation level.
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44 But because the details of this sensor are 1
not well known, it may require some differences in how 2
it's qualified. And I have not seen anything, this 3
is, what you put in Chapter, in the technical report, 4
in Rev. 1 of it, where you said we're going to at 5
least do radiation levels, but then the next question 6
is well, what about fluence.
7 And so I'm not sure I've seen that 8
anywhere in what I've looked at. But it would be good 9
to give me some sort of reference where I can see that 10 you're thinking about all the variables that might 11 impact this first-of-a-kind sensor.
12 Go ahead, Charlie.
13 MEMBER BROWN: I just wanted, and when I 14 read this, I guess I didn't glom onto this. I presume 15 this analysis is assuming you've got 12 modules 16 operating.
17 MR. MAXWELL: Yes, sir.
18 MEMBER BROWN: In that circumstance. You 19 switch between DNPM, as opposed to each NuScale NPM.
20 I got lost in the transition, so you've answered my 21 question.
22 MR. MAXWELL: So the next slide will help 23 a little bit with that. And this is the boundary 24 condition. So again, this is tracking from existing 25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.
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45 industry guidance. Boundary conditions for the event 1
are that the beyond design basis event occurs, 2
impacting all modules at the site.
3 All modules are initially operating at 4
power unless the site has a procedural direction to 5
shut down for the impending event. Each module will 6
successfully shut down when required. All rods are 7
inserted, there is no anticipated transient without 8
9 Onsite staff is at site administrative 10 minimum shift staffing levels. No independent 11 concurrent events, for example, no security threat.
12 All personnel onsite are available to support the site 13 response. And spent fuel and dry storage is outside 14 the scope of this event.
15 MEMBER CORRADINI: I think you're going to 16 discuss this but just to, in anticipation. But what 17 makes you guys unique, I thought you wrote somewhere 18 in chapter is you're, you have a higher probability of 19 something in transition to refueling, and that's going 20 to be a particular mode that you're going to analyze 21 specifically for this.
22 MR. MAXWELL: And we did, and we took, we 23 considered a --
24 MEMBER CORRADINI: If you're going to do 25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.
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46 it later, you can wait.
1 MR. MAXWELL: I don't, we don't have a 2
slide specific to that, so I'll just describe it 3
briefly. Here is that what we did is we considered a 4
module that was in transition, so it had been cooled 5
down. In order to achieve the state of transition you 6
cool down the module, you pull it up, and you open the 7
ECCS valves.
8 So I've got a module now that's on the 9
reactor building crane. It's been moved over to the 10 containment tool, and we've lifted it to its highest 11 point to be set into the pool, into the refueling 12 pool. And that's at that moment that that's when the 13 ELAP occurs.
14 And we did an evaluation, and it was also 15 if we provided adequate core cooling for beyond 50 16 days. It was still, it was not bounding compared to 17 the other modules.
18 Additionally, while we did look at that, 19 we also looked at, well, in transition, you know, 20 you'd say that the initial condition's better off than 21 compared to an operating module that you're already 22 cooled down and flooded.
23 And so we're looking now specifically at 24 the amount of time that you spend at that elevation 25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.
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47 where there's less cooling, depth of cooling to the 1
ultimate heat sink. And something along the lines of 2
.02% of an operating cycle that the module will spin 3
in that state.
4 MEMBER RICCARDELLA: Crane stops working 5
so it's sitting there for 50 days or something.
6 MR. MAXWELL: That's correct. And you 7
know, we've kind of jumped into what the operators 8
will be doing. And of course there's design features 9
that allow manual operation to lower the module with 10 the crane, that's correct, manually. But the analysis 11 shows that it wouldn't be required.
12 MEMBER MARCH-LEUBA: But wouldn't the 13 limiting one when would be if you put in the refueling 14 machine sits there at that unlimited position, and 15 it's not DHRS.
16 MR. MAXWELL: There's no --
17 (Simultaneous speaking.)
18 MR. MAXWELL: Right, but you're submerged.
19 Now you're just in the ultimate heat sink. Now you 20 have the entire capacity of the ultimate heat sink.
21 MEMBER MARCH-LEUBA: Not when you lower 22 the level past the top of the head. Or did you lower 23 the level past the top of the open head?
24 MR. MAXWELL: Well we, the modules flooded 25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.
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48 up, all the way up to the baffle plates. Now we put 1
it in the C tool, remove the bottom head of the 2
containment. It's still flooded within --
3 MEMBER MARCH-LEUBA: And the opening is at 4
what elevation? That top opening?
5 MR. MAXWELL: I don't know that number.
6 MEMBER MARCH-LEUBA: Is it greater or 7
lower than 45?
8 MR. MAXWELL: Lower, much, much lower than 9
45 feet.
10 MEMBER MARCH-LEUBA: Much lower.
11 MR. MAXWELL: Yes, sir.
12 MEMBER MARCH-LEUBA: Okay.
13 MR. MAXWELL: All right, so now that we've 14 established these boundary conditions, we'll, we took 15 a look. We evaluated to determine if the design met 16 the coping criteria. So I want to describe the 17 NuScale power plant response to an extended loss of AC 18 power concurrent with the loss of normal access to the 19 normal heat sink. And without any operator action and 20 without use of any offsite resources.
21 So within the first minute of the event, 22 you receive a reactor trip. Decay heat removal system 23 initiation and containment isolation for all 12 24 modules. That makes all the reactors sub-critical and 25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.
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49 places in service the decay heat removal sufficient to 1
establish safe shutdown conditions.
2 Twenty-four hours into the event, at the 3
24-hour mark, the module protection system de-4 energizes the trip solenoids for the ECCS valves, 5
allowing the ECCS valves to open and place ECCS into 6
service.
7 Yes, sir. It floods it -- it partially 8
transfers reactor system to the containment vessel.
9 So it puts some coolant into the containment and some, 10 while some stays in the reactor above the top fuel.
11 At this condition, all 12 modules are in 12 safe shutdown with passive decay heat and containment 13 cooling. And the spent fuel in the spent fuel pool 14 remains passively cooled by the inventory of the 15 ultimate heat sink.
16 MEMBER MARCH-LEUBA: I mean, your analysis 17 at 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br />, you remove the DHRS cooling. I mean you 18 drained it.
19 MR. MAXWELL: It becomes of significantly 20 reduced effectiveness because of ECCS in operation.
21 MEMBER MARCH-LEUBA: You're only in the 22 steam, DHRS is only in the steam area, it's not 23 condensing.
24 MR. MAXWELL: That's correct.
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50 MEMBER MARCH-LEUBA: But that's assumed, 1
that is calculated in your modeling?
2 MR. MAXWELL: Yes. What we did was use 3
the station blackout analysis. The first 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br /> of 4
the station blackout is identical to an ELAP. And we 5
use that analysis to predict the response.
6 MEMBER MARCH-LEUBA: Because if I remember 7
correctly, the conductivity through the containment is 8
only like.5% nominal power. Certainly less than one 9
percent.
10 MR. MAXWELL: I don't know the answer to 11 that question.
12 MEMBER MARCH-LEUBA: That's the number of, 13 actually, 0.6% is the number that sticks to my head 14 and I've heard sometime. And that, it's awfully close 15 to decay heat.
16 MR. MAXWELL: Well, yeah --
17 MEMBER MARCH-LEUBA: If you've run the 18 calculation properly.
19 MR. MAXWELL: That's correct.
20 MEMBER MARCH-LEUBA: I'm not in the 21 business of arguing with computer codes if you've done 22 it.
23 MR. MAXWELL: We have a calculation that 24 did consider this. You know, if DHRS is in service 25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.
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51 for the first 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br />, and then transferring over to 1
Emergency Core Cooling System at 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br />.
2 Okay, again, like I said now so we're in 3
safe shutdown on the 12 modules and the spent fuel in 4
the spent fuel pool just continues to be passively 5
cooled by the ultimate heat sink inventory. During 6
all this period, the ultimate heat sink is heating up, 7
and it begins to boil after more than five days.
8 When the pool begins to boil in our 9
analysis we assume that none of the inventory returns 10 back to the pool. Level begins decreasing. Again --
11 MEMBER MARCH-LEUBA: Well before that you 12 will start evaporating.
13 MR. MAXWELL: Right.
14 MEMBER MARCH-LEUBA: Which will mean the 15 containment level building around the pool, and we'll 16 have an environment similar to Florida yesterday. And 17 everything will be condensing, any instrumentation, 18 anything that has -- everything in building survives 19 condensing moisture?
20 MR. MAXWELL: All the safety-related 21 equipment necessary is qualified to the pool 22 environment that's in that area --
23 MEMBER MARCH-LEUBA: Is it qualified for 24 99% humidity and condensing?
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52 MR. MAXWELL: Correct.
1 MEMBER MARCH-LEUBA: What happens to the 2
steam when you start boiling it? Because that 3
building is closed.
4 MR.
MAXWELL:
There are
- pressure, 5
overpressure reliefs in the reactor building, safety-6 related overpressure reliefs.
7 MEMBER MARCH-LEUBA: Like a safety relief 8
valve? Cooling down service, same function.
9 MR. MAXWELL: That's correct. Like again, 10 after more than five days the pool begins to boil and 11 it just, again to point out, so you know operator 12 action. The level in the pool would begin to 13 decrease, and it would reach 45 feet, which we said 14 earlier was just below the top of the DHRS passive 15 condensers, after more than 50 days.
16 MEMBER CORRADINI: So can I ask a 17 question? Jose asked it, and maybe I misunderstood.
18 So there is pressure relief from the building to the 19 environment?
20 MR. MAXWELL: That's correct.
21 MEMBER CORRADINI: If I then go through a 22 change of conditions where there's a negative 23
- pressure, is there pressure relief from the 24 environment back into the containment -- into the 25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.
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53 reactor building?
1 MR. MAXWELL: I don't know the answer to 2
that, I'll have to take --
3 MEMBER CORRADINI: Does somebody know that 4
in the design? Does it go, does it swing both ways?
5 In other words, if I have an overpressure does that go 6
out? If it starts breathing, will it allow it to come 7
back in if I start condensing steam too much? Because 8
I'm going to essentially flush all the air out of the 9
system, right?
10 MR. MAXWELL: Right.
11 MEMBER CORRADINI: As I approach boiling, 12 the partial pressure of steam is going to essentially 13 take over. So I'm curious if I then get a lower 14 pressure, will there be an inflow?
15 MR. MAXWELL: I understand the question, 16 unfortunately I don't know the answer to that.
17 MEMBER CORRADINI: Can you take it down 18 and get back to us?
19 MR. MAXWELL: Yes, we can.
20 MEMBER CORRADINI: Thank you.
21 MEMBER BLEY: My memory from work that was 22 done on cylindrical containments --
23 MEMBER CORRADINI: Well, this is a 24 building, it's not a cylindrical --
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54 MEMBER BLEY: No, if you get into that 1
condition though so that you've got a few inches of 2
reverse pressure. You aren't built for that kind of 3
strength.
4 MEMBER CORRADINI: Well, but --
5 MEMBER BLEY: Weird things can happen.
6 MEMBER CORRADINI: But as long as they've 7
got a, I expect you're going to tell me they had a 8
damper, like a door. The door opens, the door closes, 9
it swings both ways.
10 MR. MAXWELL: I think we're going to find 11 this more along the lines of a rupture.
12 MEMBER CORRADINI: Because where I'm going 13 with this essentially is -- I'm in -- well, I'll stop.
14 MR. MAXWELL: I'll get the official 15 answer for you.
16 MEMBER CORRADINI: That's fine, that's 17 fine. Okay, thank you.
18 MR. MAXWELL: So now we've got, like I 19 said, the pool level has dropped down to 45 feet.
20 Again, that takes more than 50 days for that to 21 occur. During that period, passive core cooling and 22 containment cooling are assured.
23 And just, again, I'm pointing out that the 24 45 feet is not significant in any regard to the 25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.
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55 ability to cool the fuel or containment. It's just 1
where the long-term cooling calculation analysis 2
terminated.
3 Regarding the spent fuel pool cooling 4
safety function itself, it continues to be maintained, 5
even if the level in the ultimate heat sink is allowed 6
to lower. And after more than four months, the 7
ultimate heat sink level would reach the bottom of the 8
opening in the weir wall that separates the spent fuel 9
pool from the rest of the ultimate heat sink pools.
10 And that level's significant. Before that 11 point, pools are in communication with one another and 12 the reactor pool and the refuel pool act as a makeup 13 source to the spent fuel pool for that period. And 14 once the walls, once the pools are separated and we're 15 just looking at the spent fuel pool for cooling of the 16 spent fuel, it still requires another month, up to 17 five months before the level would reach the top of 18 the spent fuel rack.
19 CHAIR REMPE: This is my ignorance of the 20 regulations, but the fact that you've separated out 21 the fact that operators have, some plant person has to 22 replace the battery, it's not included in the 23 requirements to meet this particular aspect.
24 MR. MAXWELL: That's correct.
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56 CHAIR REMPE: So your subtitle about plant 1
response without operator action or offsite resources 2
applies for this particular criterion. But later with 3
the spent fuel and then is where you hit up about the 4
batteries might have to be replaced.
5 MR. MAXWELL: Right, this condition would 6
still exist, because this isn't level monitoring, it's 7
just the pool passively lowering and the safety 8
functions continuing to be maintained during this 9
period. Then yes, you're right that we separate.
10 Then there's the paragraph E requirement specific to 11 spent fuel pool level indication.
12 CHAIR REMPE: Okay. Well, I go further.
13 Then the staff though has applied broadly. We're not 14 going to do anything beyond 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br /> in the response 15 that they, what they have in their draft SE. And they 16 went ahead and because they don't have analysis beyond 17 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br /> is why they stopped on this, when it wasn't 18 because they needed an operator action or anything 19 like that?
20 Is there a primary reason plus, or is that 21 your understanding of why they stopped on 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br /> for 22 this?
23 MR. MAXWELL: Let, they would like to 24 speak to that.
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57 CHAIR REMPE: Okay, well, I'll let them 1
speak to it later. Are you still strong that you want 2
50 days or whatever? Or that's your, the NuScale 3
stance here still?
4 MR. BERGMAN: Hi, Tom Bergman, NuScale, 5
again. Yes, we would like to have the coping period 6
of 14 days approved and the recognition that 14 days 7
represents indefinite given the resources required at 8
that point. So we're calculating it to 14 days. The 9
50 days shows we have plenty of margin for 14 days.
10 PARTICIPANT: Yeah, I think the 50 days is 11 just a calculation.
12 MR. MAXWELL: Right, that's what we, you 13 know --
14 CHAIR REMPE: And you believe you have 15 adequate documentation to support that with what 16 you've provided with this Rev. 1 technical report.
17 MR. BERGMAN: Correct. It was also -- I 18 can't remember the day but it was a March 2019 letter 19 to NRO where we laid out the rationale for what we're 20 doing as well.
21 The DCA has now been brought in, the 22 technical reports have been brought up to date. That 23 letter, which is referenced in the Staff SECY paper, 24 provides that basis for the 14 days.
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58 CHAIR REMPE: Okay, thank you.
1 MR. MAXWELL: So, now with the pipe 2
response being covered, we're going to remove two of 3
the individual key safety functions, beginning with 4
core cooling.
5 The success criteria we looked at and the 6
criteria are for the equipment relied upon to provide 7
satisfactory fuel cooling performance and to maintain 8
the fuel covered at all times.
9 With the containment isolation that occurs 10 in that first minute, within the first minute of the 11 event initiation, the reactor coolant system inventory 12 required to meet these criteria is preserved for the 13 duration of the event.
14 The core cooling itself is provided as 15 we've established in the first 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> by the decay 16 heat removal system and then the remainder of the ELAP 17 via the emergency core cooling system.
18 Also essential for core cooling is the 19 ultimate heat sink inventory.
20 Core cooling, again, occurs initially 21 through transfer of heat to the ultimate heat sink to 22 the DHRS passive condensers, which are submerged in 23 the ultimate heat sink and then transfers to heat 24 transfer from the containment vessel with ECCS in 25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.
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59 operation.
1 The passive heat removal to the ultimate 2
heat sink is capable of maintaining core cooling for 3
more than 50 days without pull inventory makeup or 4
operator action.
5 Next safety function is containment. The 6
containment function is provided by the containment 7
isolation valves and the containment vessel.
8 As we just mentioned, there's containment 9
isolation that occurs within the first minute of the 10 event by a module protection system automatic 11 response.
12 The containment vessel temperature and 13 pressure are passively controlled by heat removal of 14 the ultimate heat sink.
15 And the parameters reach their peak value 16 during ELAP immediately following opening of the ECCS 17 valves, again, which happens after DHRS has been in 18 operation for 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br />, reducing RCS temperature.
19 And pressure over that period and the 20 opening of the ECCS valves itself does not represent 21 a challenge to the containment integrity.
22 So, with the ultimate heat sink inventory 23
-- without any addition or any other operator actions, 24 the containment cooling is maintained for more than 50 25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.
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60 days.
1 The third key safety function is spent 2
fuel pool cooling.
3 Just a couple minutes ago we discussed the 4
pools of the ultimate heat sink and in this figure we 5
can see the rear wall itself that separates the spent 6
fuel pool from the refuel pool and the opening in the 7
wall, the weir that allows the movement of fuel 8
between the two pools using the refuel machine.
9 And that opening is significant because 10 it's what allows the spent fuel pool to communicate 11 with the other pools and initially causes the ultimate 12 heat sink to respond as a single volume to the event 13 until level lowers below or to that point.
14 And again, as described earlier, at that 15 point it's just the inventory in the spent fuel pool 16 that's providing cooling to spent fuel. It still 17 would require more than 150 days for the level to 18 passively boil down to the top of the spent fuel rack.
19 The last topic I'll talk about, with 20 respect to again just to the mitigation strategy and 21 monitoring and with respect to that, just to the 22 mitigation strategy, pipe monitoring is not necessary 23 because there are no operator actions to establish and 24 maintain the three key safety functions for more than 25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.
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61 50 days following the initiation of an ELAP.
1
- However, the instrumentation is 2
instrumentation DC electrical power provided in the 3
design that allows the control room operators to 4
observe the response of the installed plant equipment 5
to verify the conditions necessary for coping had been 6
established.
7 These indications remain available for a 8
minimum of 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br />.
9 MEMBER MARCH-LEUBA: You're saying that 10 the batteries share the load, drop an unnecessary load 11 but keep the control room alive for 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br />?
12 MR. MAXWELL: That's correct.
13 MEMBER MARCH-LEUBA: Is that what you're 14 saying?
15 MR. MAXWELL: Yes.
16 MEMBER CORRADINI: So, you said something 17 earlier and I wanted to kind of return back to it.
18 So, as you said, the philosophy is that 19 this essentially is, to put it in terms, is a 20 hands-off response where the operators are free to 21 then address the initiators and cure or reestablish.
22 23 So, what would be in the emergency 24 operating procedure realm, not this realm, to 25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.
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62 reestablish battery charging to get the batteries so 1
they'd go beyond 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br />? Can you remind me what 2
that is?
3 MR. MAXWELL: They're not --
4 MEMBER CORRADINI: I assume it's EOPs that 5
they would be following?
6 MR. MAXWELL: Right, and forgive me, it's 7
not my area of expertise. I can't remember the name 8
of --
9 MEMBER CORRADINI: It's not mine either so 10 just take us down the path.
11 MR. MAXWELL: If you look at the displays 12 for the operator, it's the three key safety functions 13 that they evaluate.
14 And I'm a visual thinker, I'm looking at 15 the panel in my head here, but there's the three key 16 safety functions and then, essentially, they're the 17 backup functions. So, once the three key safety 18 functions are established and maintained, here are the 19 other areas that you need to address.
20 And one of them is electrical distribution 21 and entering that procedure will direct the operators 22 to restore power, to start the backup diesel 23 generators, to get the auxiliary AC power source 24 running and ready for electrical loading.
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63 So, there are procedures for those 1
defense-in-depth components, if you will, that will 2
direct the operators to take those actions.
3 MEMBER CORRADINI: And those would, based 4
on EOPs and even with the stylized accent, those would 5
occur simultaneously?
6 MR. MAXWELL: That's correct.
7 MEMBER CORRADINI: Thank you.
8 MEMBER RICCARDELLA: So, going back to 9
your picture with the rear wall?
10 MR. MAXWELL: Yes, sir.
11 MEMBER RICCARDELLA: There's nothing that 12 causes circulation, natural or otherwise, between the 13 main side and -- so one could get considerably warmer 14 than the other.
15 It's just that if it boils off, the level 16 will stay the same, right?
17 MR. MAXWELL: That's exactly right. The 18 heat load in the spent fuel pool -- the pool boil-off 19 calculation was very conservative. It assumes 18 20 years' worth of spent fuel in the pool including a 21 fresh full-core offload.
22 So, the heat load being more significant 23 than the reactor and refuel pool and the volume being 24 smaller, the spent fuel pool boils off faster. And 25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.
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64 again, the refuel pool make up, essentially acts as a 1
makeup source.
2 MEMBER RICCARDELLA: It's like the hot tub 3
in a swimming pool?
4 MR. MAXWELL: That's correct. So, now 5
with the discussion of the mitigation strategies 6
complete, we move into the spent fuel pool monitoring 7
portion of the rule, which is covered by Paragraph 8
Echo.
9 The objective of this part of the rule is 10 to provide a reliable means to remotely monitor 11 wide-range spent fuel pool water level until five 12 years have elapsed since all of the fuel within the 13 spent fuel pool was last used in the reactor vessel 14 for power operation.
15 And the intent is that the operators have 16 the information necessary to prioritize event 17 response. The NuScale ultimate heat sink system 18 includes remote level indication for the following.
19 It's got reactor pool, refuel pool, and 20 two dedicated indicators for the spent fuel pool.
21 These indicators are seismically qualified 22 as well as qualified for the environment of the pool 23 area during an ELAP, and are normally powered by our 24 highly reliable DC power system via the plant 25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.
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65 protection system.
1 MEMBER MARCH-LEUBA: Would you go back to 2
the cartoon and show where the refueling pool is?
3 MR. MAXWELL: Yes, sir.
4 MEMBER MARCH-LEUBA: Where is the third 5
pool? Because I only see two.
6 MR. MAXWELL: What this isn't showing you 7
in this mimic is that the elevation of this floor is 8
below the reactor pool.
9 MEMBER MARCH-LEUBA: It's a continuous 10 mass of water?
11 MR. MAXWELL: It is.
12 MEMBER MARCH-LEUBA: There is no rear wall 13 there?
14 MR. MAXWELL: That's correct, no wall.
15 The difference is just the --
16 (Simultaneous speaking.)
17 MEMBER MARCH-LEUBA: It's still the pool, 18 you just call it Section A, Section B?
19 MR. MAXWELL: That's correct. It could be 20 thought of another way as two indications for spent 21 fuel pool level indication on this side of the rear 22 wall and two indicators for pool level on the other 23 side of the rear wall.
24 In addition to the 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br /> of battery 25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.
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66 power from the highly reliable DC power system, the 1
design would include for these level indicators a 2
replaceable battery power source that's independent 3
from the plant AC and DC power systems.
4 And those batteries will have a minimum 5
capacity of 14 days.
6 MEMBER MARCH-LEUBA: Capacity to provide 7
what?
8 MR. MAXWELL: To provide indication for 9
these spent fuel pool level indicators.
10 MEMBER MARCH-LEUBA: It will power the 11 instrumentation? Where is the display, the control 12 room?
13 MR. MAXWELL: The location of the display, 14 final location, hasn't been determined but what is 15 required is that it's remote from the pool area.
16 MEMBER MARCH-LEUBA: It has to be in an 17 accessible location.
18 MR. MAXWELL: That's correct.
19 MEMBER MARCH-LEUBA: The USS is not 20 accessible.
21 MR. MAXWELL: That's exactly right.
22 MEMBER BLEY: What keeps this replaceable 23 battery from supplying power to other things?
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67 of being completely divorced from the AC and DC power 1
system. It's independent of and divorced from the AC 2
and DC distribution system.
3 MEMBER BLEY: I don't remember seeing 4
details of this. Are they available somewhere?
5 MR. MAXWELL: The final instrument hasn't 6
been selected, just we're implementing the requirement 7
for --
8 MEMBER BLEY: The electrical side isn't 9
laid out anywhere.
10 MR. MAXWELL: No, sir, not at this time.
11 I just want to point out that it's specific to the 12 instrument.
13 This is not part of our electrical 14 distribution system at all, it's going to be specific 15 to the spent fuel pool level instrument.
16 MEMBER BLEY: So, you would have to 17 disconnect a normal power source and then insert this 18 replaceable battery source?
19 MR. MAXWELL: Again, we haven't selected 20 our --
21 MEMBER BLEY: You don't know exactly?
22 MR. MAXWELL: I can tell you that at my 23 old plant ours divorced itself and a loss of power 24 relay dropped out and just put the replaceable battery 25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.
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68 in service.
1 MEMBER BLEY: So, there will be one there 2
permanently?
3 MR. MAXWELL: That's correct, a permanent 4
install.
5 MEMBER BLEY: And it will be charged 6
permanently but it will somehow disconnect when you 7
get to this point?
8 MR. MAXWELL: That's correct.
9 MEMBER BLEY:
And when you say 10 replaceable, is there the intent that at some point 11 when it starts running down, you could stick a new one 12 in there so you'll keep these instruments?
13 MR. MAXWELL: That's the intent. Again, 14 without having selected the permanent design, I can 15 tell you that there's designs that are capable of the 16 batteries.
17 MEMBER BLEY: It will be for all of these 18 level instruments, not just one?
19 MR. MAXWELL: All four.
20 MEMBER BLEY: Have you done that for any 21 other instruments that you know of?
22 MR. MAXWELL: Not that I'm aware of.
23 MR. SCHULTZ: Chris, is this then the 24 system that is time-limiting in terms of the 14 days?
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69 In other words, you're putting this into place so that 1
you can support a 14-day timeframe?
2 MR. MAXWELL: I would say that the 3
mitigation strategy, again, keeping it separate from 4
the spent fuel pool level indication, worked on 5
require spent fuel pool level indication to mitigate 6
the beyond-design-basis event.
7 So, this is separate, the 14-day battery 8
is separate, to the spent fuel pool level indication 9
requirement, Paragraph
- Echo, not to the B1 10 requirements.
11 Because we don't credit or need the spent 12 fuel pool level indicators as part of our mitigation 13 strategy.
14 MR. SCHULTZ: But you're putting the 15 replaceable battery power source in place so that you 16 can support 14 days as it relates to this requirement?
17 MR. MAXWELL: Correct, Paragraph Echo 18 requirement.
19 MR. SHULTZ: Okay.
20 MEMBER RICCARDELLA: But if they're 21 constantly charging during normal operation, wouldn't 22 you expect them to last 14 days?
23 MR. MAXWELL: I expect them to last 17 24 days because the first 3 days they'll be supplied by 25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.
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70 the highly reliable DC power system.
1 I'd actually expect it to be 20 days, 2
frankly, but once the EVS batteries are no longer 3
available, that's when these batteries would be placed 4
into service.
5 And their allowance is made in the rule 6
for intermittent operation but we haven't finalized 7
what instrument we're going to use.
8 MEMBER BLEY: That would be something you 9
do by procedure or it might even --
10 MR. MAXWELL: That's correct.
11 So, to summarize, the two different 12 portions with regards to the pipe mitigation strategy, 13 the NuScale strategy, is to rely on the automatic 14 response of the permanently installed safety-related 15 plant equipment to establish and maintain the three 16 key safety functions and to provide extended coping 17 capabilities of greater than 14 days.
18 And again, this strategy doesn't require 19 any AC or DC power, or any inventory addition, or any 20 operator action to be placed into service or to be 21 maintained.
22 And regarding the spent fuel pool level 23 indication strategy, they rely on the installed 24 instrumentation I've just described. And included in 25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.
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71 that is a 14-day battery backup power supply.
1 MR. SCHULTZ: But you don't really need 2
that to satisfy the condition of the fuel? The fuel 3
is fine for 50 days, 50-plus days?
4 MR. MAXWELL: That's correct.
5 MR. SCHULTZ: So, you don't need to spend 6
this money, you could spend it on something else if 7
you didn't have to meet this requirement?
8 MR. MAXWELL: That's correct.
9 MR. SCHULTZ: But you can do it and do so.
10 Okay, thanks.
11 MR. MAXWELL: That's the end of the 12 Chapter 20 presentation if there's questions.
13 CHAIR REMPE: I'm going to delve a little 14 bit more about what I tried to ask earlier about what 15 would be required to get the Staff to go to a 14-day 16 approval.
17 If they were to decide to do this, they 18 probably would ask for a lot more analyses to be 19 submitted, which would require a lot more review on 20 their part as well as they'll be RAIs and all that 21 stuff.
22 And there's always pressure about oh, it 23 costs so much for a design certification but you guys 24 are willing to step up and say whatever it takes that 25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.
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72 the Staff think they need, you're willing to provide 1
it.
2 It does cost money to have this additional 3
work done, right?
4 MR. MAXWELL: I'll defer to the licensee 5
for the response.
6 MR. BERGMAN: Tom Bergman, NuScale. We 7
believe we've already done the work to provide that 8
information in our latest submittals.
9 CHAIR REMPE: I heard that earlier but you 10 realize there will be RAIs. The Staff had not 11 intended to do more than 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br />. Is there a 12 response back?
13 And if they come back and say, okay, well, 14 you guys want it, we'll do it, and they start asking 15 a lot of RAIs and ask for additional analyses?
16 MR. BERGMAN: Then we can revisit our 17 decision but Chapter 20 is written as a substantial 18 investment. We'd like to get the maximum return on 19 that investment.
20 CHAIR REMPE: Sure, I bet. Okay, just 21 exploring the boundaries here. We're scheduled for a 22 break now, are there any other questions?
23 MEMBER SKILLMAN: I had one. Chris, I'm 24 in your mitigation strategy in your Section 522 25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.
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73 reactivity control and just let me make two points.
1 I'm going to read from your document so 2
you understand why I'm saying what I'm saying. For 3
Boundary Condition 3 in Section 313, when reactor trip 4
occurs in the ELAP event, all control rods fully 5
insert.
6 This action achieves initial 7
subcriticality, however, depending on the time and 8
core life, for some currently licensed designs the 9
control rods alone may not provide sufficient negative 10 reactivity to compensate for the positive reactivity 11 added as the core cools.
12 I'm interpreting that as a rhetorical 13 reference to other plant designs, not the NuScale 14 design. Then you say to account for this the NuScale 15 plant design includes a unique core design limit.
16 I'm assuming that unique in that context 17 means it's unique to the way the NuScale license is 18 written.
19 MR. MAXWELL: Unique in that it's not 20 typical of designs.
21 MEMBER SKILLMAN: Okay, so it's back to 22 the former, more general discussion. Unique meaning 23 all those other PWRs out there and not necessarily 24 ours?
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74 MR. MAXWELL: Correct.
1 MEMBER SKILLMAN: Okay, because what you 2
go on to say then or what this document then says is 3
the hot full-power critical boron concentration is 4
such that a cold zero power with all rods inserted K 5
effective is less than one.
6 I've operated a 508 percent, a 2791 7
cooler, a 24-month fuel cycle and I've been out 690 8
days at 18 PPM. And we push the scram button, it goes 9
subcritical.
10 So, I think that the limit that you're 11 talking about is at the end of core life with a 508 12 percent core, 690, because you're in a 24-month fuel 13 cycle, you're out 690, 700 days.
14 And even at that very low boron 15 concentration, whether it's 10 or 30, at least the way 16 you're writing your license, you will be 5 percent 17 subcritical or 1 percent subcritical, you're simply 18 saying you're subcritical.
19 MR. MAXWELL: Unfortunately, I don't know 20 that I'm smart enough to answer your question fully.
21 MEMBER SKILLMAN: I think you're saying 22 the end of
- life, no matter what the boron 23 concentration is, it shuts down.
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75 with sufficient boron concentration with all rods in 1
to be subcritical.
2 MEMBER SKILLMAN: And even as it cools 3
from there, you still remain subcritical?
4 MR. MAXWELL: That's correct.
5 MEMBER SKILLMAN: Gotcha. Thank you.
6 CHAIR REMPE: Mike, did you have a 7
question?
8 MEMBER CORRADINI: I'm good.
9 CHAIR REMPE: So, if there aren't any 10 other questions --
11 MS. JOERGENSEN: I'd like to make a 12 comment. There was a question on the negative 13 pressure in the building, whether the vents would 14 allow it to relieve overpressure and also allow air to 15 come back into the building.
16 So, the answer is the reactor building 17 ventilation system maintains a negative pressure by 18 design. If boiling occurs, the overprotection is a 19 ruptured disc and steam goes out.
20 It would not reclose and if there is a 21 later negative differential due to steam condensation, 22 air would be pulled back in.
23 MEMBER CORRADINI: Thank you.
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76 scheduled for our break, let's take it and come back 1
until 2:40 p.m. by this clock, okay? Thank you.
2 (Whereupon, the above-entitled matter went 3
off the record at 2:24 p.m. and resumed at 2:41 p.m.)
4 MR. TABATABAI: Okay, good afternoon, 5
everyone. My name is Omid Tabatabai, I'm a Senior 6
Project Manager in the Office of New Reactors.
7 And we're here to present the Staff's 8
evaluation of NuScale's Chapter 20 safety evaluation 9
application and the design certification application.
10 But before we get started, I would like 11 for Kevin Coyne who's here and he's the Director of 12 our Division of Safety Assessment, Risk Analysis, and 13 Engineering.
14 So, Kevin will be making some introductory 15 remarks on behalf of the Staff. Kevin?
16 MR. COYNE: Thanks, Omid. Kevin Coyne, 17 Acting Director, Division of Engineering, Safety 18 Systems, and Risk Assessment. And thank you for the 19 opportunity to greet the Subcommittee today.
20 Needless to say, the ACRS reviews are very 21 valuable to the Staff and provide good feedback that 22 we then incorporate into our reviews. And in 23 particular, thank you for the flexibility and 24 scheduling of a full Committee Meeting tomorrow.
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77 I know that's unusual but it was important 1
to NuScale, important to the Staff to try to get to 2
the full committee as soon as we could.
3 So, the mitigation of beyond-design-basis 4
event review that the Staff has been doing has evolved 5
since NuScale first submitted their application.
6 It's worth noting that the MBDBE orders 7
and the rule are not applicable to a design 8
certification.
9 But to the extent an Applicant chooses to 10 describe certain design aspects of the SSCs used to 11 provide the mitigation strategies in their FSAR, the 12 Staff can review that and provide some level of 13 finality based on that review.
14 Looking to our OGC, I just wanted to make 15 sure I got that part right. So, legitimate to review 16 but it's not required for the design cert.
17 NuScale has asked for the reviews so the 18 Staff is going through the review. We've briefed ACRS 19 on our MBDBE reviews and the past HMP was obviously 20 the most recent one.
21 That review criteria was against the 22 orders that were issued after the accident at 23 Fukushima Daiichi. Since that time, the Commission 24 has approved the new rule, 5150(5).
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78 So that was another driver for the 1
evolution of how the review is going to proceed in 2
this case. So, the Staff will brief on the SE that 3
we've generated but it should note that that SE is 4
largely based on Rev 2 of the FSAR.
5 Subsequent to us receiving Rev 2 to 6
Chapter 20, NuScale has significantly changed the 7
approach for their mitigation and beyond-design-basis 8
event strategies and has submitted a markup to the 9
Staff describing those changes.
10 So, we expect our SE to change based on 11 our review of the markup, however, we will describe 12 today the review criteria that we intend to use to 13 apply to the NuScale review.
14 So, I just wanted to let everyone know 15 it's a bit of a review in motion here. We will go 16 through the review criteria that we intend to use and 17 then answer any questions you guys have on that.
18 MEMBER RICCARDELLA: But the presentation 19 material that we just saw, was that per the markup or 20 per the original Rev 2?
21 MR. COYNE: I believe that reflects 22 NuScale's current position on their compliance with --
23 MEMBER RICCARDELLA: Which is what you 24 referred as the markup.
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79 MR. TABATABAI: Yes.
1 MEMBER CORRADINI: So, is the markup then 2
connected with the Revision 1 of the technical report 3
that supports the chapter?
4 MR. COYNE: Yes.
5 CHAIR REMPE: My understanding is the 6
Staff will not be doing anything to reflect the 7
revised information that we saw today and the Rev 1 of 8
the technical report.
9 You're going to issue the SE pretty much 10 as is without accommodating this additional 11 information.
12 What we're trying to get to is, is this 13 the right time for us to be writing a letter or should 14 we wait if you're going to do an update in the next --
15 MR. COYNE: so, that's not a question I 16 can answer but I can tell you that we have different 17 phases in the review. So, what you have is the Phase 18 2 SE. It is what it is.
19 We will generate a Phase 4 SE, we have a 20 milestone date of mid-December to make that publicly 21 available.
22 And so that Phase 4 SE would definitely 23 reflect the current NuScale approach and our review 24 approach for that information.
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80 MEMBER RICCARDELLA: But if we were to 1
write a letter now we could comment on the criteria 2
that you're going to use for that evaluation. So, 3
that's what you said you're going to present today, 4
correct?
5 MR. COYNE: Correct. So, we will cover 6
the criteria that we intend to apply to the review 7
today.
8 MEMBER CORRADINI: Okay, maybe we'll just 9
ask the questions at the end instead of the beginning 10 because we'll take you on all sort of what-ifs.
11 So, once we see the criteria -- but the 12 criteria are not going to be any different than what 13 you would have applied to any other -- they're 14 design-specific for the NuScale design.
15 MR. COYNE: Ryan will cover that.
16 MEMBER CORRADINI: Okay, fine.
17 CHAIR REMPE: I'd like to also point out 18 that the SECY paper is not public yet but it will be 19 within a few weeks.
20 But I know one Member has already 21 approached me and said they'd like to have a closed 22 session to discuss this a little bit more.
23 And so we might want to also have some of 24 these questions after we get through the public 25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.
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81 portion of today's meeting. Okay?
1 MR. NOLAN: It should be publicly released 2
Friday.
3 CHAIR REMPE: Unfortunately, we've got to 4
do this now but yes, we'll discuss it a little bit 5
more.
6 MEMBER RICCARDELLA: If we're going to 7
write a letter it will be written by Friday.
8 CHAIR REMPE: Go ahead.
9 MR. TABATABAI: Thank you, Kevin. This 10 afternoon, we will be talking about some background 11 information.
12 As Kevin mentioned, this review has been 13 kind of dynamic in terms of information that we have 14 received and also the regulations that have been 15 operated and issued lately.
16 We will describe the Staff's review 17 approach and we will share with you some of the 18 preliminary findings that we have made in terms of our 19 evaluations.
20 The word preliminary here is because as 21 you know, these findings are based on kind of an older 22 version of information and review criteria. So, we 23 will be updating those in Phase 4.
24 We will describe our review of NuScale's 25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.
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82 mitigating strategy and that is basically the topic of 1
the SECY paper that you mentioned. And Ryan will be 2
talking in detail about that.
3 And then we will describe our Phase 4 4
review strategy and plans. Before starting our 5
presentation, I'd like to recognize our team of 6
reviewers.
7 As you see, we have quite a few reviewers 8
who contributed to this review and preparing the SER 9
from various offices, NRR, NSER, and NRO. This slide 10 basically summarizes what Kevin mentioned during his 11 introductory remarks.
12 We received Rev 2 of Chapter 20 or design 13 certification application in October 2018. In January 14 the Commission approved the final MBDBE rule which 15 will be codified in 10 CFR Part 50S 50.155.
16 NuScale informed the Commission, the NRC 17 Staff, in March of 2019 that now that the rule has 18 been finalized they will revise their Chapter 20 to 19 make confirming changes to the information.
20 We received NuScale's Revision 3 or draft 21 Revision 3 markups on June 10th of this year and then 22 on June 14th, we received Revision 1 to the ELAP 23 topical report, extended loss of AC power.
24 One June 26th the Staff issued their SECY 25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.
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83 paper which kind of describes how we plan to complete 1
the review of NuScale's Chapter 20 and the title of 2
the SECY paper is Staff Review of NuScale Power's 3
Mitigation Strategy for Beyond-design-basis External 4
Events.
5 And we are expecting for the rule to be 6
publicly available around September 2019.
7 MEMBER BLEY: I'm sorry, say that again?
8 MR. TABATABAI: In 2019 10 CFR 50.155 will 9
be published in the Federal Register.
10 MEMBER BLEY: Okay.
11 MR. NOLAN: Yes, it will be published and 12 final at that point.
13 MEMBER BLEY: So back in March -- Rev 2 of 14 Chapter 20 is up on your public website?
15 MR. TABATABAI: That's correct.
16 MEMBER BLEY: Did you say you now have Rev 17 3?
18 MR. TABATABAI: Yes, it was submitted on 19 June 10th.
20 MEMBER BLEY: You haven't really looked at 21 that yet or have you?
22 MR. TABATABAI: It is a markup, it is not 23 part of an entire DCA package. The entire DCA package 24 will arrived late August.
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84 MEMBER BLEY: Okay.
1 MR. TABATABAI: But it is publicly 2
available.
3 MEMBER BLEY: Oh, it is?
4 MR. TABATABAI: It is.
5 MEMBER BLEY: Okay, are there substantial 6
changes?
7 MR. TABATABAI: Yes.
8 MEMBER BLEY: From 2 to 3?
9 MR. TABATABAI: Yes.
10 MEMBER BLEY: There are. And 11 they're consistent with Rev 1 of the tech report?
12 MR. TABATABAI: I will have to -- these 13 documents have been submitted very recently. We have 14 not completed detailed --
15 MR. NOLAN: Yes, but I think they were 16 revised together. So, Rev 3 of the FSAR and I think 17 Rev 2 of the tech report will be consistent.
18 MR. TABATABAI: NuScale wants ELAP to 19 support Revision 3 but, again, from the Staff's 20 perspective, we have not reviewed --
21 (Simultaneous speaking.)
22 MEMBER CORRADINI: Sure, but I think Ryan 23 said something I want to make sure of. So what is in 24 theory consistent? Rev 3 and TR-1? Or Rev 2 and 25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.
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85 TR-1?
1 MR. TABATABAI: Rev 3 and TR-1.
2 CHAIR REMPE: Is Rev 3 on the NRC's 3
website? Where is it?
4 MR. NOLAN: We've received a draft markup 5
and then when the entire FSAR is submitted as part of 6
Rev 3, which is expected at the end of August 7
timeframe.
8 CHAIR REMPE: So we cannot see Rev 3 right 9
now?
10 MR. TABATABAI: I can provide the ML 11 number. You can search it. It is not on the website 12 but it is in ADAMS, publicly available.
13 MEMBER BLEY: Well, if you can give us the 14 ML that would be good. Thank you.
15 CHAIR REMPE: While we're asking for 16 things, I saw that the SECY does refer to this March, 17 whatever, 19 letter that was mentioned earlier today.
18 And it's a publicly available ML number or 19 do I have to go to the private one?
20 MR.
TABATABAI:
No, it's publicly 21 available.
22 Staff's Phase 2 review approach, as I 23 mentioned, because of the timing of different 24 submittals and availability of Staff's review 25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.
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86 guidance, the latest final rule is not reflected in 1
that.
2 Although, it's part of SRM SECY which was 3
issued in January. That's the latest publicly 4
available guidance document that we have.
5 But most of our, I mean all of our, 6
evaluation findings in the SER are based on Revision 7
2 of the NuScale DCA.
8 These are the lists of all of the 9
regulatory documents or guidance documents that we 10 used to evaluate NuScale's DCA Rev 2.
11 And based on the documented information, 12 our findings currently are only for the first 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br /> 13 after initiation of a beyond-design-basis event.
14 MEMBER CORRADINI: I want to make sure, so 15 the SECY gives the rationale as to why you're stopping 16 at three days?
17 MR. TABATABAI: That's correct. The SECY 18 is not public yet but --
19 MEMBER CORRADINI: I understand. When it 20 is, the reasoning for that bullet is there?
21 MR. TABATABAI: That's correct. The last 22 part of the SECY discusses why the Staff is going only 23 up to 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br />.
24 MEMBER CORRADINI: Okay.
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87 MR. NOLAN: And we'll touch on it.
1 MEMBER BLEY: It talks about how you're 2
doing the review as well, which you can tell us now?
3 MR. TABATABAI: Yes.
4 MEMBER BLEY: Go ahead.
5 MEMBER SKILLMAN: Omid, on that slide, 6
please, you identify it as NEI 1206 Rev 2 but in the 7
safety evaluation you identify that the key safety 8
functions are identified in NEI 0612 Subsection 423.
9 You also communicate it's NEI 0612 10 Revision 3. So, is there a disconnect between this 11 slide and what is in your safety evaluation?
12 MR. TABATABAI: No, there were actually 13 different revisions. It depends whether or not the 14 NRC proved or endorsed any of those NEI guidance 15 documents.
16 I
think in the SER for different 17 subsections in Chapter 20, you might notice various 18 NEI revisions or various guidance. But on this slide 19 I have kind of listed those major recurring themes 20 that you see in the SER.
21 It doesn't really include every single 22 revision of the NEI or 1206 or 1202. It doesn't list 23 all of that. This is what the main, basically the 24 main, guidance documents that we have used.
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88 MEMBER SKILLMAN: Well, then I mean 1
confused because it seems that this is referring to --
2 it's on Page 34 of the PDF.
3 It is technical evaluation 20.2.4 and this 4
sets out what the Staff has identified as the key 5
safety functions. So, this is the heart of your 6
review.
7 MR. TABATABAI: Right. Under LOLA --
8 MR. ASHLEY: Hi, this is Clint Ashley from 9
the Staff. I think the confusion is these numbers are 10 NEI 1206 and NEI 60612.
11 One of them, the first one, is for 12 mitigation strategies. The second one is for loss of 13 large areas. And so that's why you'll see those two 14 numbers in the safety evaluation, because Chapter 20 15 of NuScale covers both topics.
16 MEMBER SKILLMAN: Fair enough, thank you.
17 MR. TABATABAI: Next slide. So, on this 18 slide we have summarized our preliminary findings of 19 NuScale Chapter 20 information.
20 There are four subsections in Chapter 20.
21 Section 20.1 talks about mitigation strategies. This 22 is basically what NuScale presented to the Members 23 before us and that is the subject of Ryan's 24 presentation later on during this presentation.
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89 We also reviewed Subsection 20.2, which is 1
LOLA, loss of large area, and 20.3, emergency 2
procedures, and 20.4, enhanced emergency response 3
capabilities.
4 With respect to loss of large area, the 5
Staff used SRP guidance in Section 19.4 and that 6
section basically talks about how to review to make 7
sure information or design complies with regulatory 8
requirements in 50.54 HH2.
9 In that section, the Staff specifically 10 looked at five different criteria with respect to RCS 11 reactor cooling system inventory or RCS heat removal, 12 containment isolation and containment integrity, and 13 released mitigation.
14 I just don't want to get into details of 15 the review but we looked at the SRP guidance and 16 looked at the information that NuScale had provided.
17 And we confirmed that the information in 18 the design meets the regulation. We have no open 19 items on this topic, we won't have any issues.
20 MEMBER BLEY: Something still isn't 21 completely clear to me. I thought when I read their 22 Chapter 20, NuScale's Chapter 20, that they based it 23 on the draft mitigation beyond-design-basis event 24 rule.
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90 Is that true, number one? And then number 1
two, the final rule you said will come out later in 2
the year and the revision will essentially be against 3
that.
4 Are those two statements both correct?
5 MR. TABATABAI: Yes.
6 MEMBER BLEY: Okay, thank you.
7 MEMBER DIMITRIJEVIC: Well, I have one 8
really basic question. I'm not sure, how did you take 9
out considering damage to ultimate heat sink?
10 Because ultimate heat sink is always part 11 of the beyond-design-basis events and here something 12 says, okay, they have this big pool and this is not 13 any, I mean, I don't know, seismic size or whatever, 14 sink opening like in CAD, the damage done.
15 MR. NOLAN: Yes, so the 5150(5) rule techs 16 addresses this specifically for passive plants and 17 that is loss of access to the normal heat sink, not 18 the ultimate heat sink for passive designs.
19 MEMBER DIMITRIJEVIC:
So, it does 20 specifically say that?
21 MR. NOLAN: Yes.
22 MEMBER DIMITRIJEVIC: Interesting, based 23 on what?
24 MEMBER CORRADINI:
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91 connecting what Charlie asked and what we were talking 1
about actually at break, which is they're using the 2
same terminology, whether it be an active plant or a 3
passive plant.
4 MEMBER DIMITRIJEVIC: I understand the 5
difference in terminology. I'm just sort of surprised 6
that damage to this big pool through the big seismic 7
event, was not considered.
8 That's what I am sort of -- it's not a 9
part of beyond-design-basis events, that's why I'm 10 surprised.
11 MR. NOLAN: So, if it's being relied on 12 for mitigation strategies of the beyond-design-basis 13 external event, it would still need to be reasonably 14 protected.
15 And the NEI guidance steps through -- I 16 think they use the phrase robustly protected. And so 17 we would still ensure that any SSC that's relied on 18 for the mitigation strategies is appropriately 19 protected for that event.
20 MEMBER DIMITRIJEVIC: For which event?
21 MR. NOLAN: Beyond-design-basis external 22 event.
23 MEMBER DIMITRIJEVIC: Yes, but that can be 24 anything. A seismic event in magnitude, right?
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92 MR. NOLAN: So, the guidance specifies 1
it's designed to the design basis SSC.
2 MEMBER DIMITRIJEVIC: Of the design basis?
3 MR. NOLAN: Yes.
4 MEMBER DIMITRIJEVIC:
But this is 5
beyond-design-basis?
6 MR. NOLAN: That's correct.
7 MEMBER RICCARDELLA: Yes, but as I 8
understand it that's no different than the operating 9
plants with their FLEX equipment, right? Their FLEX 10 equipment is not designed for a beyond-design-basis 11 earthquake.
12 (Simultaneous speaking.)
13 MEMBER BLEY: That is true, Pete.
14 MEMBER RICCARDELLA: That is true. But 15 again, considering seismic, what it's designed for is 16 different, I think, than what it's ultimate capacity 17 really is.
18 So, it's designed for maybe -- the SSC is 19 like a ten to the minus four event but the containment 20 or any of this equipment could probably survive a ten 21 to the minus six event without actually failing.
22 Because there's margins and safety factors 23 in the design. As we've seen this morning, we've seen 24 plants survive earthquakes that are significantly 25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.
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93 above their SSC.
1 MEMBER BLEY: But you can't assume that 2
it's --
3 MEMBER RICCARDELLA: No, you can't assume.
4 (Simultaneous speaking.)
5 MEMBER BLEY: -- the magnitude. I think 6
the one thing you can say is all the cases where 7
people have really looked hard, it's not a cliff.
8 If you go a little bit beyond, you aren't 9
all of the sudden in trouble. It drops off.
10 MEMBER RICCARDELLA: Well, I guess the key 11 is that should probably be part of the seismic PRA for 12 this plant.
13 MEMBER BLEY: It certainly should be, yes.
14 MEMBER DIMITRIJEVIC: This is a different 15 situation.
16 I mean this is beyond-design-basis event 17 and in this case if we consider just damage, let's 18 say, leak or spillover or something due to a seismic 19 event, they have to prove they have makeup capability 20 within the timeframe, right?
21 Which is not part of the discussion.
22 MR. NOLAN: So, for the purposes of this 23 discussion, we are just implementing the rule as 24 written.
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94 And so if you take a look at the rule 1
text, I think it's 5150(5)(C)(2), it says that the 2
equipment must be reasonably protected from the 3
effects of natural phenomena that are equivalent in 4
magnitude to the phenomena assumed for developing the 5
design basis of the facility.
6 So, that's what the rule specifies.
7 MEMBER BROWN: I want to understand just 8
one more time here.
9 The extended loss of all AC and the loss 10 of the ultimate heat sink issue is fundamentally 11 assumed that 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> later the ECCS comes on?
12 Whenever it's triggered, it assumes that 13 the reactor pool remains intact through all of this?
14 MR. NOLAN: That's correct.
15 MEMBER BROWN: So, seismic event reactor 16 pool, that's really the loss of the ultimate heat sink 17 and that's assumed not to happen? The ultimate --
18 (Simultaneous speaking.)
19 MR. NOLAN: Right, that assumption goes 20 beyond what the rule specifies.
21 (Simultaneous speaking.)
22 MEMBER BROWN: Whether it's realistic or 23 not, it's beyond the point. That's what the rule 24 says.
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95 MEMBER RICCARDELLA: But Charlie I mean 1
has I think cracked the ultimate sink is probably 2
something that's not a big deal. Total destruction 3
would be a big deal.
4 MEMBER BROWN: I agree with you. If it 5
starts leaking, when do they start adding water back 6
in? 30 days when they statute replenishing? Or if 7
they have to from the boil, 45 days? 50 days?
8 Whatever it was, there was some number of 9
days when they would have to start making up inventory 10 in the reactor pool. So, if it cracks you're going to 11 lose some, I presume, 50 days.
12 Even if they could start doing at 30 days, 13 it's based on all the risks so it would probably be 14 okay. I'm being too generous right now.
15 All right, you answered my question, thank 16 you.
17 MR. TABATABAI: Okay, the last point I'd 18 like to make on this slide is that we understand that 19 Revision 3 to Chapter 20 will not have these Sections 20 20.3 and 20.4.
21 In the SER, because there are some COL 22 action items listed under 20.3 and 20.4 and we're 23 defining the findings on those COL items to the COL 24 application stage, not during the design certification 25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.
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96 stage, but according to -- the new rule doesn't 1
require them and NuScale we understand will not list 2
any COL action items for these items, emergency 3
procedures or enhanced emergency response.
4 CHAIR REMPE: I know you said it clearly 5
but I just want to make sure because the current 6
version that I reviewed basically just says there's a 7
COL action and they're just going to have nothing on 8
those two sections.
9 MEMBER CORRADINI: Per the new rule?
10 MR. TABATABAI: Yes.
11 CHAIR REMPE: Because the new rule says 12 not to do that? Which hasn't been issued yet, the new 13 rule, because it's not coming out until September of 14 2019.
15 MR. TABATABAI: The Rev 3 to design 16 certification application comes in August, last 17 August, and that will be available publicly. But the 18 rule will be published in September some time.
19 CHAIR REMPE: Interesting.
20 MR. SCHULTZ: Right now it's really just 21 a placeholder for these and they're going to take out 22 the placeholders?
23 MR. TABATABAI: That's correct.
24 MR. SCHULTZ: And you're going to accept 25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.
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97 that these items can be discussed at the COL stage and 1
that review will be done in detail then?
2 MR. TABATABAI: That's correct.
3 And I think when Ryan goes through his 4
presentation, one of the reasons we're talking about 5
72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br /> is responsibility of COL Applicants versus 6
design certification.
7 So, with
- that, my portion of the 8
presentation is finished and I'll turn it over to 9
Ryan.
10 MR. NOLAN: All right, thanks Omid. The 11 first few bullets here is kind of an overview.
12 We've discussed a lot of this already but 13 from a regulatory framework perspective the recently 14 approved regulation, 5150(5), for mitigation for 15 beyond-design-basis events does not apply to 16 Applicants for design certification.
17 So, it would be applicable to the COL but 18 not to the design certification Applicant. And as was 19 stated previously, NuScale is voluntarily seeking the 20 NRC to approve the use of its installed design 21 features for the mitigation strategies.
22 As many of you are already aware, the 23 NuScale design incorporates several unique design 24 features that provide enhanced coping capability for 25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.
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98 extended losses --
1 MEMBER BLEY: I've been trying to parse 2
your opening statement and I thought I understood that 3
it does not apply to Applicants for a design cert. I 4
thought it had COL up there.
5 But you said it will apply to COL?
6 MR. NOLAN: It does apply to the COL.
7 MEMBER BLEY: Okay.
8 MR. NOLAN: And so NuScale is seeking 9
finality to the extent -- yes.
10 CHAIR REMPE: I know this kind of goes 11 between both of you but earlier today we heard, well, 12 other Applicants have done something like KHMP did.
13 Did they do more than just the mitigation 14 and beyond-design-basis events? Did they also do the 15 LOLA?
16 And I know I participated in the letter, 17 I'm just trying to remember did they do the thing 18 about emergency procedures and integration of 19 procedures and emergency response?
20 Or did they focus just on LOLL and 21 mitigation of beyond-design-basis events?
22 MR. NOLAN: I can't recall the specifics.
23 Is there anyone out there who can speak to 24 the procedure side of -- from a LOLA perspective, they 25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.
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99 address the design features, which is typical of what 1
most design cert Applicants have done.
2 So, they've addressed the design feature 3
piece of the LOLA requirements.
4 CHAIR REMPE: Do they have to do it?
5 MR. NOLAN: No.
6 CHAIR REMPE: It's a --
7 (Simultaneous speaking.)
8 MR. NOLAN: Yes, 5054(h)(h)(2) is similar 9
in that it's only applicable to the licensee. In this 10 case it would be the COL.
11 MR. TABATABAI: Bob Vettori is our lead 12 reviewer for that area.
13 MR. VETTORI: Okay, for LOLA all the 14 operational stuff's going to go in the COL. That's 15 what KHMP did also.
16 CHAIR REMPE: Okay. You have to say who 17 you are, I'm sorry.
18 MR. VETTORI: I'm sorry, Bob Vettori, NRO.
19 MR. NOLAN: And I guess since we were 20 talking about LOLA just now, I'll just make the point 21 that the 5054(h)(h)requirements are getting absorbed 22 into 5150(5).
23 And so once 5150(5) is published, 24 50549(h)(h) will kind of transfer over.
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100 You can go to the next slide. I just put 1
this up here for reference since it's probably been a 2
little while since some of you have seen the rule 3
text. Maybe it's new to a lot of you as well.
4 And these are just the pertinent portions 5
of 5150(5) just for your reference.
6 MR. SCHULTZ: Ryan, I don't see 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br /> 7
mentioned anywhere here. You've got lots of 8
dot-dot-dots. I didn't think it was.
9 MR. NOLAN: Yes, it actually says 10 indefinitely, the rule says indefinitely.
11 And I'll talk a little bit more about the 12 criteria we're using but the main goal is to remain 13 consistent with what was done for the operating fleet 14 as well as the previous design cert Applicants.
15 MR. SCHULTZ: Thank you.
16 MR. NOLAN: So, as a brief overview, 17 NuScale already went over a lot of this, but their 18 approach, because of the uniqueness of their design, 19 they rely mostly on safety-related SSCs, their AC and 20 DC independent systems.
21 And I think many of you have seen what 22 that event progression looks like. They're requesting 23 a minimum coping duration of 14 days with the 24 justification that 14 days provides sufficient time 25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.
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101 for a licensee to establish an alternate means of heat 1
removal.
2 And then the last point here is the 3
position that there's no reliance on monitoring for 4
mitigation strategies.
5 And there was a few notes in their March 6
28th letter and I think in the technical report, I 7
haven't looked at the FSAR too closely, but there's a 8
couple points that say instrumentation is expected to 9
be available in the near term and that monitoring is 10 there as a
supplementary capability.
11 CHAIR REMPE: So, I know it's in a later 12 slide but it has your plans to document that it's not 13 relied on unless but it's expected. And I think 14 that's in the SE also.
15 How are you planning to make sure your 16 expectations are met with respect to qualification of 17 the instrumentation?
18 MR. NOLAN: Sure, I think we looked at it 19 from a robustness, to make sure that it's robustly 20 protected.
21 It's designed for the SSC, it's located 22 inside protected areas, not susceptible to wind or 23 flooding hazards. It's protected to the external 24 event.
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102 CHAIR REMPE: So, protection from external 1
events is your way of making sure that -- you've heard 2
me whine about I want to make sure that it will be 3
qualified for the fluence levels it may experience.
4 And is that going to be codified somehow, 5
like in the ITAC, for qualifying the instrumentation?
6 MR. TABATABAI: I believe it's already a 7
design commitment. Dinesh Taneja is walking to the 8
microphone to explain it.
9 MR. TANEJA: This is Dinesh from NRO, NRC 10 Technical Reviewer. So, a lot of these instruments 11 that are relied on upon are part of their normal 12 instrumentation.
13 If you look at Chapter 3, your EQ 14 requirements, for example, containment level, right 15 now is required to be operational for 100 days, to 16 qualify for 100 days of operation. So, that is a 17 design commitment.
18 Seismic, radiation, and temperature so the 19 EQ qualifications.
20 CHAIR REMPE: And the radiation will be 21 for the flux levels or fluence that it experiences?
22 MR. TANEJA: 100 days post-accident. So, 23 whatever that total integrated dose is, that's what 24 needs to be qualified.
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103 CHAIR REMPE: And that's actually in 1
Chapter 3?
2 MEMBER DIMITRIJEVIC: Chapter 3, 3.10.
3 2.10. There's a table for the instruments and what 4
the requirements are.
5 CHAIR REMPE: Okay, I'll check again.
6 Thank you for reminding me.
7 MEMBER BLEY: I know you guys have used 8
robust a lot and it jumped off the page at me reading 9
their Chapter 20, Robust Makeup Line with External 10 Connection Point.
11 I take it robust is defined in one of the 12 NEI documents or both of them, and is it defined in a 13 qualitative way? And can you explain that?
14 Or is it defined in some kind of 15 quantitative way?
16 MR. NOLAN: I don't have that information 17 in front of me right now.
18 MEMBER BLEY: Whoever's decided you agree 19 that these things are robust, what does that mean?
20 MR. HERNANDEZ: Hello, my name is Raul 21 Hernandez from Bottle Supply. You're talking about 22 the makeup line to the spent fuel pool?
23 MEMBER BLEY: That was the one that jumped 24 off the page at me but it's used over and over and 25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.
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104 over again and I heard it referenced that it's the 1
NEI document that requires all of these things to be 2
robust.
3 And I want to know what that means, either 4
from your interpretation of the NEI document or how 5
you guys used it, not just for that line but for all 6
of these cases.
7 MEMBER RICCARDELLA: I want to 8
echo Dennis's question because the Applicant uses 9
that. And so the Staff have an agreement on what the 10 definition is.
11 MEMBER BLEY: Somebody told us earlier 12 it's as defined in one of the NEI documents, I forget 13 which one. But if you can tell us what it means --
14 (Simultaneous speaking.)
15 MR. HERNANDEZ: For the level instruments 16 of --
17 MEMBER BLEY: And why is that true? How 18 did you decide that or did you just --
19 MR. HERNANDEZ: It is described in Section 20 9.1.3, spent fuel pool design. It discloses the 21 makeup line and the NEI documents, if I'm not 22 mistaken, is 1206.
23 MEMBER BLEY: It's in 06?
24 MR. HERNANDEZ: That's for the level 25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.
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105 instrument, that's the one that I'm responsible for.
1 MEMBER BLEY: So, it's not defined in a 2
general way?
3 MR. NOLAN: I think from a qualitative 4
sense it's protected to the applicable hazard, right?
5 And so it needs to be protected to wind and missiles, 6
to snow and ice, to the seismic event.
7 MEMBER BLEY: So you think that's the way 8
it's --
9 MR. NOLAN: Yes, so if it's being relied 10 on for mitigation strategy it needs to be protected to 11 those hazards.
12 MEMBER BLEY: In a qualitative sense it 13 converts to a quantitative sense in specific examples.
14 MR. TABATABAI: Dr. Bley, Peter Bamford is 15 from the Japan Lessons Learned so he can probably --
16 MR. BAMFORD: Peter Bamford, NRR. I 17 worked on a lot of the operating plant reviews.
18 Robust is defined in NEI 1206, there's a definition of 19 this action and it's defined there.
20 Specifically, what it means is you can be 21 robust in a couple of different ways. One is if it's 22 safety-related protected to all the plants, external 23 hazards, that would generally qualify as robust.
24 Because safety-related, it meets all the 25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.
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106 seismic, tornado, flooding, any of the postulated 1
external events.
2 In addition, a licensee could show by 3
analysis, let's just say they had a piece of equipment 4
that was not necessarily safety-related but they could 5
show by either analysis or test it would likely be 6
available after the postulated external events.
7 Those would be considered as robust also 8
and all that is encompassed in the definition in NEI 9
1206. I hope that helps.
10 MEMBER BLEY: That helps a lot, thank you.
11 MR. SCHULTZ: And NuScale puts those 12 prescriptions associated with the external events, 13 they list the conditions from Chapter 3 I believe it 14 is, that defines what the equipment will survive for 15 each of the events.
16 Cold, heat, seismic, and so forth.
17 MR. NOLAN: Right, and so it's short-hand 18 up here but most of the SSCs that NuScale's relying on 19 are safety-related.
20 One exception is the EDSS, the batteries, 21 however, they have unlimited quality, they are 22 designed to the SSC as specified in Chapter 3 as well 23 as those other requirements imposed on the battery 24 system.
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107 MEMBER BROWN: The 14 days for alternative 1
heat removal, that means your ability to put water 2
into the spent fuel pool or into the reactor pool?
3 Which one is it?
4 (Simultaneous speaking.)
5 It's not totally the same thing. Don't 6
you have to overflow? I thought there was something 7
you had to overflow from the spent fuel pool to get 8
into the --
9 MR. NOLAN: Yes, the connection is to the 10 spent fuel pool.
11 MEMBER BROWN: I thought I read something 12 about something had to overflow into something, from 13 one part to -- I forgot which way it went.
14 MEMBER RICCARDELLA: Spent fuel over the 15 weir to the --
16 MEMBER BROWN: To the reactor pool. So, 17 if the reactor pool boiled up, you'd fill the spent 18 fuel and it would spill over into the reactor. My 19 memory is not as bad as I thought, thank you.
20 MR. NOLAN: And if you're only at decay 21 heat levels, I wouldn't expect the water level to be 22 below the weir within 14 days.
23 MEMBER BROWN: No, that's why based on the 24 other discussions I was assuming that boil-off would 25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.
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108 occur almost two times that much but I don't remember 1
the exact numbers.
2 PARTICIPANT: It looks like the weir is 3
uncovered at 130-something days.
4 PARTICIPANT: 150.
5 MEMBER BROWN: No, the top of the fuel, 6
not the weir.
7 PARTICIPANT: The weir comes before that.
8 MEMBER BROWN: That's right.
9 PARTICIPANT: It's ten feet above.
10 MEMBER BROWN: Thank you.
11 MR. NOLAN: Okay, so the next few slides 12 I'm going to go over the Staff's review approach.
13 MR. SCHULTZ: Ryan, before you leave that 14 slide, that's the last time you mentioned 14 days.
15 MR. NOLAN: Right, that's what NuScale is 16 proposing.
17 MR.
SCHULTZ:
That's what they've 18 proposed?
19 MR. NOLAN: Correct.
20 MR. SCHULTZ: Let's wait until you're 21 finished then.
22 MR. NOLAN: So, like I mentioned before, 23 one of the most important things for our review 24 approach is to maintain consistent with what we've 25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.
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109 done for the operating plants as well as previous 1
design certifications.
2 We've received several SRMs from the 3
Commission reiterating consistency with the operating 4
reactors and implementing this rule.
5 MEMBER CORRADINI: So, by saying it that 6
way, can I translate that?
7 MR. NOLAN: Sure.
8 MEMBER CORRADINI: So, you don't feel that 9
you have the ability to go beyond three days to make 10 a judgment because it's not in the regulation or what?
11 MR. NOLAN: It's not necessary.
12 MEMBER CORRADINI: Not necessary?
13 MR. NOLAN: To go beyond 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br />.
14 MEMBER CORRADINI: Because technically --
15 MR. NOLAN: At the design cert level. And 16 so for the operating plants what we did is -- the 17 focus of the staff's review is on the initial 18 response.
19 This is where the most critical and 20 time-sensitive actions are projected to occur. And 21 there wasn't a lot of review that was performed once 22 you get our far in time.
23 MEMBER CORRADINI: So, this is the one 24 part I guess I and to investigate for me at least.
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110 So, the 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br /> in some sense is the 1
equivalent of Phase 3 of the current plants in terms 2
of Phase 1 install, Phase 2 FLEX, Phase 3 beyond FLEX 3
to safer?
4 Approximately.
5 MR. NOLAN: There's variations, yes.
6 MEMBER CORRADINI: Okay, so I'm still 7
trying to understand the technical reason.
8 The technical reason you're saying is 9
because all the crucial stuff occurs in the first 10 three days and after that things should be stable and 11 therefore there's no need to look at it?
12 MR. NOLAN: At the design certification 13 level.
14 MEMBER CORRADINI: So, because NuScale is 15 going beyond that to help the potential 16 owner/operator, Staff doesn't feel compelled to 17 analyze it yet?
18 MR. NOLAN: Right, we'll take a look at 19 the post-72-hour strategy during the COL review.
20 That's discussed on the next slide.
21 MEMBER CORRADINI: Okay, all right, but 22 I'm trying to formulate this correctly. If it's 23 obvious that they can make it past 72 days, you don't 24 feel compelled to note that in the design 25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.
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111 certification analysis?
1 MR. SCHULTZ: That's what I was going to 2
get to later, that question.
3 MEMBER CORRADINI: Sorry.
4 MR. SCHULTZ: No, that's fine.
5 MR. NOLAN: We don't feel it's necessary 6
for us to make a regulatory finding beyond the 72 7
hours. It's not required for us to make any 8
regulatory finding.
9 This rule is not applicable to the design 10 cert Applicant, right? It's applicable to the COL.
11 And so right now where we are with the review, we can 12 make a 72-hour reasonable finding and then beyond 13 that, it will be the responsibility of the COL.
14 And like I said, it's consistent with what 15 we did for the operating reactors. That's where the 16 focus of the Staff review was, was there.
17 We did not spend a lot of resources 18 looking out two weeks, three weeks, four weeks. But 19 it's consistent with what we did for --
20 MR. SCHULTZ: But the operating reactors 21 have invested a lot to demonstrate what would happen 22 at 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br /> and beyond. That's the industry response 23 that's associated with it.
24 I don't want to speak for NuScale but I 25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.
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112 thought they were trying to get some understanding 1
that the design of this facility is such that one 2
would not have to do something at 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br />.
3 And if we could get some determination 4
that 14 days is a reasonable time to paint the picture 5
of what needs to be done when, rather than 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br />, 6
it would make the COL, the potential COL Applicants, 7
more excited about this design than hearing that it's 8
a 72-hour stopping point where they've got to do 9
something more, including analysis or whatever else it 10 might be.
11 So, they're asking for 14 days as opposed 12 to 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br />, getting an agreement up above but you 13 don't necessarily have to make a determination as part 14 of your design cert agreement, right?
15 MR. NOLAN: Yes.
16 MR. SCHULTZ: Have you decided not to give 17 them that or are you --
18 MEMBER BROWN: That's what the SECY's all 19 about.
20 MEMBER BLEY: And that part of it I think 21 isn't a public discussion at this time. We can have 22 a session later.
23 MEMBER BROWN: It isn't, you're probably 24 right. I didn't think about that.
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113 CHAIR REMPE:
But in the public 1
discussion, though, you can say that -- do you have 2
enough information? Do they give enough out?
3 Or have you just not looked at anything 4
beyond three days? Do you think there's enough 5
information or you think it would -- they're going to 6
have to --
7 MR. NOLAN: It would require more work 8
most likely on both sides.
9 CHAIR REMPE: You've looked at it enough 10 to say this is going to take a lot more?
11 MR. NOLAN: Right, so as you're aware, 12 during the Chapter 15 presentation there's a few 13 transient phenomena that we're evaluating and we 14 expect to resolve that for the 72-hour timeframe.
15 But it would probably take a closer look 16 to make findings that go beyond 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br />.
17 CHAIR REMPE: Such as recriticality?
18 MR. NOLAN: Correct.
19 MEMBER CORRADINI:
But I
thought 20 criticality doesn't apply to this event? It applies 21 when you're missing a rod.
22 (Simultaneous speaking.)
23 MR. NOLAN: It doesn't apply to this.
24 MEMBER DIMITRIJEVIC: It doesn't apply to 25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.
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114 this event. Actually, you don't have any difference.
1 (Simultaneous speaking.)
2 MR. SCHULTZ: Based on the stylized 3
assumptions, it doesn't apply.
4 MR. NOLAN: Well, it depends on what event 5
and phenomena you're talking about. If you're talking 6
about boron redistribution, that's just a transient 7
phenomena that is potentially going to occur.
8 The difference here is we would assume all 9
rods in so that buys a lot of margin. In Chapter 15 10 we would assume one rod out.
11 MEMBER CORRADINI: I know we're not 12 allowing you to go down your normal path but such is 13 life.
14 In the draft SE, the identification of 15 boron dilution is one of the things that is 16 renumbered as an open item but is unresolved in this 17 regard?
18 MR. NOLAN: Right, and so following this 19 approach that we're laying out here, we would not 20 expect that to be an issue for Chapter 20 review.
21 We would take another look at that during 22 the COL and as part of the COL review we would look to 23 make sure there isn't any credible transient phenomena 24 that can affect recriticality or anything else for 25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.
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115 that matter.
1 MEMBER CORRADINI: You got me there 2
because I thought you were going to say something 3
different. So, what I read in the draft SE, in 4
essence, doesn't apply now because of the 72-hour 5
consideration?
6 MR. NOLAN: That's with the assumption 7
that Chapter 15 will resolve the issue.
8 MEMBER CORRADINI: Ah, okay, sorry. It's 9
still tied back to 50?
10 MR. NOLAN: Yes.
11 MEMBER CORRADINI: Okay, excuse me, sorry, 12 I misunderstood. Thank you.
13 MEMBER DIMITRIJEVIC: I don't see the real 14 logic here. I don't see why -- why when you pass 24 15 hours1.736111e-4 days <br />0.00417 hours <br />2.480159e-5 weeks <br />5.7075e-6 months <br /> would this analyze this? Everything is the same 16 up to -- I mean, there is not any reason for you to 17 stop at 72.
18 Even in the earlier discussion, this rule 19 doesn't apply for this situation. You don't really 20 have any reason to stop at 72 logically. If you give 21 them 72, the 14 days are completely the same.
22 So, I don't really see. I heard your 23 discussion about this Chapter 15 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br /> but that 24 doesn't apply. You have rules which are applicable 25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.
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116 here.
1 MR. SCHULTZ: I took it from the 2
Applicant's response to the question about the spent 3
fuel pool instrumentation and the DC power required 4
for that, that that is their conclusion.
5 That if they can provide that power for 6
that instrumentation, then 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br /> and 14 days are 7
the same, if you will. That was the only piece that 8
they see is required to demonstrate 14 days.
9 MR. COYNE: Kevin Coyne, NRO.
10 So, in Ryan's next slide he's going to 11 talk a little bit more about the expectations for the 12 COL relative to some of the discussion.
13 But going beyond 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br />, one of the 14 considerations the Staff had is given NuScale's unique 15 features and enhanced capability to deal with the 16 damaged state that's assumed in 5150(5), we didn't 17 want to create a de facto, more restrictive standard 18 for the review than what we applied to the operating 19 reactors.
20 And so having to make a regulatory finding 21 after 14 days for NuScale could be viewed as imposing 22 a more restrictive criteria for the review for Chapter 23 20 than what we would apply to the operating fleet.
24 CHAIR REMPE: Could you elaborate why you 25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.
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117 think it's going to be more restrictive?
1 Yes, you went two more hours but what's 2
going to be more restrictive than for the operating 3
reactors, other than you're going to be doing 4
something more in depth for a longer period of time?
5 MR. COYNE: So, I think just that, that we 6
would be doing a more in-depth review for a longer 7
time period.
8 MEMBER RICCARDELLA: But I thought I heard 9
someone say you will be doing that at the COL stage?
10 Did I hear that?
11 MR. NOLAN: And I'll talk about that on 12 the next slide. The last point I'd like to make on 13 this slide is that what we're reviewing are the design 14 aspects.
15 It's the installed SSCs, that's what, if 16 granted, the Commission would be providing finality 17 on. The operational aspects or procedures training, 18 that's all deferred to the COL, which is typically 19 what we'd expect for procedural development.
20 MEMBER CORRADINI: So, let me say it a 21 different way just so I'm clear.
22 So, the 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br /> at this stage, even 23 though it's not necessary for the DCD, going beyond 72 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> could set up a precedent for going in the past 25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.
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118 and I assume into the future?
1 MR. NOLAN: Right, yes, it's not necessary 2
for us to make a finding beyond 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br />.
3 MEMBER CORRADINI: And the SECY is 4
informational, it's not a vote?
5 MR. NOLAN: Correct.
6 MEMBER CORRADINI: Yet.
7 MR. NOLAN: Correct.
8 MEMBER BLEY: Procedural question since 9
Mike brought that up.
10 I remember vaguely that when you send up 11 an information paper, if there's no voter, no SRM, at 12 some point in time it's assumed the Commission agrees 13 with you. Is that not true?
14 And what is that point in time?
15 (Simultaneous speaking.)
16 MR. NOLAN: That's a great question. I'm 17 not sure I want to be the one to step up to answer it.
18 MR. COYNE: Kevin Coyne, NRO. I don't 19 think that's a question that NRO can answer. We can 20 do a little research for you and try to get back to 21 you.
22 MEMBER BLEY: Okay, somebody's told you 23 about that in the past and I was just trying to get 24 that fixed. But, yes, do a little research and let us 25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.
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119 know.
1 CHAIR REMPE: So, at the beginning of this 2
meeting today we discussed about how we might have a 3
letter this week, we might have a letter in September.
4 Any feelers or senses that the Commission 5
is going to act on this before September that you'd be 6
willing to put on the record?
7 MR. TABATABAI: I think consistent with 8
the other Chapters that you have written letters, your 9
letters are preliminary I think, or interim reports?
10 PARTICIPANT: Interim letters.
11 MR. TABATABAI: I think interim reports is 12 appropriate in this case. I think so. I think during 13 Phase 5 you might have the final letter.
14 CHAIR REMPE: For example, if the 15 Commission decided to do more than just take the 16 information, if they did decide to respond back, no 17 one has given you any clues that's going to come 18 before September?
19 MR. TABATABAI: No, we can't predict that.
20 We can't stop the review either.
21 MR. NOLAN: So, like I mentioned on the 22 previous slide, what the Staff is reviewing for the 23 design certification is the capabilities and 24 capacities of the installed SSCs to basically satisfy 25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.
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120 the required safety functions.
1 For the COL review, if there is no 2
transient phenomena that's identified or applicable, 3
then no additional information would be needed. There 4
would be nothing else needed from a COL at that point.
5 And the basis here, well, I guess the 6
second bullet is level of detail that we expect from 7
the COL would be commensurate with the time available 8
to implement.
9 What that means is we would have to 10 understand the site, where it's located, and any 11 required operator actions.
12 And so if there's a required action to 13 refill the spent fuel pool, we wouldn't expect to have 14 detailed contracts in place to acquire that inventory 15 but we would expect to see some plan of where it's 16 coming from, what the general procedure would be.
17 MR. SCHULTZ: Are you expecting that a COL 18 is going to somehow come up with a design feature that 19 has got a spent fuel pool requirement there that's not 20 50 or 60 hours6.944444e-4 days <br />0.0167 hours <br />9.920635e-5 weeks <br />2.283e-5 months <br />?
21 But rather somewhere between 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br /> and 22 14 days? I don't know if that example fits, the 23 example you just gave.
24 MR. NOLAN: Well, I mean right now we know 25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.
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121 that water will have to be added into the pool 1
eventually. The requirement is indefinite coping and 2
so eventually water will have to be added.
3 We just have a long time constant here to 4
take those actions. And so because there's a lot of 5
time to take the action, we wouldn't expect contracts 6
in place for this design.
7 But we would expect to see some plan on 8
where's that water coming from.
9 MR. SCHULTZ: Okay, I was probably just 10 quibbling with the selection of spent fuel pool level 11 for that but I could understand it for other 12 applications perhaps.
13 I got your concept so thank you.
14 MR.
NOLAN:
And with respect to 15 instrumentation, our plan is to document that their 16 instrumentation is not relied on to support the 17 mitigation strategies, that instrumentation is not 18 needed to take operator action.
19 However, it is expected to be available 20 and meets the robust protection requirements, and it's 21 just an added assurance.
22 MR. SCHULTZ: Again, this is all aligned 23 to demonstrate that the design under the design 24 certification process meets the requirements of the 25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.
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122 new rule?
1 MR. NOLAN: That's correct.
2 MR. TABATABAI: That concludes Ryan's 3
presentation. So, where do we go from here?
4 Our plan for completing the review is to 5
follow what we have outlined in SECY 19-0066 to 6
complete the review of NuScale application when we 7
receive Revision 3 of Chapter 20 to make sure 8
information meets the requirements in 10 CFR 5150(5).
9 As I mentioned earlier, we are expecting 10 Revision 3 to be submitted in late August of this 11 year.
12 And last but not least, our full committee 13 presentation is scheduled for tomorrow and we would 14 like to receive your feedback as to what your 15 expectations are for us to present to you tomorrow.
16 If there are any specific areas that you'd 17 like us to focus on or you would like to repeat the 18 same information to the full committee, Just please 19 let us know.
20 MEMBER CORRADINI: For a practice nature 21 you're going to have one more attendee I think, unless 22 I did my math wrong. And so I think that's probably 23 the only difference in the audience.
24 But I guess I have questions I'm still 25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.
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123 struggling with. The SECY is a process SECY, that is 1
shall I or shall I not ask the Applicant for more 2
information at this juncture to decide if I go beyond 3
72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br />.
4 And the essence of the Staff's suggestion 5
not to go beyond 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br /> is a precedent-setting 6
reason as far as I can tell. Correct me if I'm wrong 7
but the way I heard the discussion was it's a 8
precedent.
9 Past plants, we looked at 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br />, future 10 plants, you might not want to look beyond 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br /> so 11 there's no reason to do this one beyond 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br />.
12 That's the essence of what I'm hearing.
13 Is that an appropriate --
14 MR. NOLAN: Consistency.
15 MEMBER CORRADINI: Okay, fine.
16 MR. SCHULTZ: Is there more analysis, 17 evaluation that the Staff needs to do to support a 18 finding of 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br />?
19 MEMBER RICCARDELLA: 72 or 14 days?
20 MEMBER CORRADINI: No, 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br />.
21 MR. TABATABAI: I think for us to make a 22 finding for up to 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br /> based on Revision 3 23 information and the SECY approach, I think the review 24 will not require a lot more requests for additional 25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.
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124 information or interactions with --
1 (Simultaneous speaking.)
2 MEMBER RICCARDELLA: A lot more or any?
3 MR. NOLAN: We would not expect any more 4
information from NuScale.
5 MR. TABATABAI: For clarification.
6 MEMBER CORRADINI: But if I take Steve's 7
question a little bit further, that would imply, 8
though, the assumption -- the but is but the connected 9
open items in Chapter 15 have to be resolved?
10 MR. NOLAN: Yes.
11 MEMBER CORRADINI: In Phase whatever?
12 Okay.
13 MR. NOLAN: Soon.
14 MEMBER DIMITRIJEVIC: What benefit would 15 it be if you approve 14 days for COL Applicant?
16 Because if they have to go infinite, it's 17 much easier for them to start in 14 days, right, 18 instead of 3?
19 MR. NOLAN: If there's no operator action 20 needed --
21 MEMBER DIMITRIJEVIC: Why is NuScale 22 asking for 14 days? What is the benefit?
23 (Simultaneous speaking.)
24 MR. TABATABAI: I think Tom Bergman 25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.
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125 explained that it's more time for the --
1 PARTICIPANT: Pardon me?
2 MR. TABATABAI: I guess marketing.
3 MEMBER RICCARDELLA: Well, then the 4
natural question is, following up to Steve, how much 5
more effort would be required to approve it for 14 6
days?
7 MEMBER DIMITRIJEVIC: None because it's 8
the same.
9 MR. NOLAN: Yes, I don't want to speculate 10 too much here but we're working these transient 11 phenomena issues in Chapter 15.
12 There's thermohydraulic analyses that 13 NuScale's performed that ends at 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br />, it doesn't 14 go beyond that.
15 We would have to take a closer look at 16 what would actually be needed to go beyond that.
17 MR. SCHULTZ: But Chapter 15 has a 18 different set of assumptions.
19 MR. NOLAN: That's certainly true, this is 20 definitely unique here.
21 MR. SCHULTZ: You're talking about certain 22 phenomena that you would like to understand better 23 given the NuScale design, is that stated about right?
24 MR. NOLAN: And the reason I'm pointing to 25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.
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126 Chapter 15 for a lot of it is because of the 1
uniqueness of the design in that a loss of all AC is 2
basically a design basis event. And so there's a lot 3
of reliance on that existing analysis.
4 You certainly don't have to rely on 5
Chapter 15 assumptions here but when we start looking 6
at boron redistribution and other phenomena, that's 7
where those issues are being looked at and addressed.
8 MEMBER DIMITRIJEVIC: Why I ask how much 9
work is required because in this part of the 10 transformation process, you're now hanging to the old 11 rule, 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br />.
12 If you can do something with minimal work, 13 say, in 14 days that will save you a lot of review and 14 time and process. For a future COL Applicant, it 15 makes perfect sense to do that.
16 Why we are hanging to this old rules? We 17 don't have to hang to old rules all the time. They 18 are not applicable for every case, you know?
19 MR. NOLAN: So, yes, going back to my 20 points on what we would review during the COLA phase, 21 if the phenomena that we're looking at as part of 22 Chapter 15, if that turns out to not be an issue, 23 there wouldn't be any additional review work needed 24 because we've already reviewed the capabilities and 25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.
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127 capacities of those systems to perform under the 1
currently realistic assumptions.
2 MEMBER DIMITRIJEVIC: But you said in COLA 3
they have to prove it to infinite period, right? In 4
the COLA phase they have to prove, that's what you 5
said, right?
6 MR. NOLAN: Well, they wouldn't have to 7
perform an analysis out that far. They have to have 8
a strategy to address the safety functions.
9 MEMBER DIMITRIJEVIC: Infinite, right?
10 MR. NOLAN: Yes, or until sufficient site 11 capabilities have been restored.
12 MEMBER DIMITRIJEVIC: But this is a 13 difference in they can bring some equipment after 14 14 days is different than after 3 days. That's what I 15 want to say.
16 So, from that point of view, it would be 17 more complicated reviews if this is stopped at 3.
18 That's how I --
19 MR. COYNE: Kevin Coyne, NRO. So, just to 20 be clear, there's nothing magic about 14 days either.
21 As Ryan pointed out, the 5150(5) wording 22 is indefinite and so the 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br /> is predicated on 23 what we need to do to review the design aspects of the 24 SSCs that were added in for the mitigating strategies 25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.
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128 that NuScale described in the FSAR.
1 And so it's not necessary for us to go 2
beyond 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br /> for that review provided there's no 3
credible transient phenomenon that we would have to 4
disposition at the COL stage.
5 There's also a thought that some of this 6
would be potentially site-specific and so at the 7
design cert stage we don't have site-specific 8
information obviously.
9 And so from a practically consideration, 10 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br /> is as far as we need to go to make the 11 finding that we need to make for the design cert given 12 that NuScale has asked for the review. That's what 13 establishes the criteria.
14 But there's nothing special about 14 days 15 either from NuScale since the criteria would 16 ultimately be indefinite or until sufficient site 17 capability exists.
18 MEMBER MARCH-LEUBA: So, from a technical 19 point of view, the only difference I see is the boron 20 redistribution, concentration of boron. Once you open 21 ECCS, you're boiling water and condensing the steel.
22 So boron is not uniformly. So maybe you 23 can make an argument for 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br /> that it has not been 24 enough cause a problem but when you go for five months 25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.
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129 in that condition, you need to resolve that in Chapter 1
- 15.
2 MEMBER CORRADINI: I agree with what Jose 3
is saying but I think the stylized accident they work 4
under here is different than in 15.
5 MR. NOLAN: Well, you have more margin to 6
work with because we assume all rods in.
7 MEMBER MARCH-LEUBA: Correct.
8 MR.
NOLAN:
But that's the only 9
difference.
10 MEMBER CORRADINI:
That's a
big 11 difference.
12 MR. NOLAN: It has a lot of margin.
13 MEMBER MARCH-LEUBA: If you are distilling 14 water, concentrated boron is somewhere, hopefully in 15 the core, somewhere else maybe.
16 Just what they need to resolve in Chapter 17 15, if you are in the process where you are distilling 18 water and changing the concentration, the longer you 19 are in that condition, the worse you are.
20 MEMBER CORRADINI: But the assumption is 21 one case is the worst rod is stuck out and the other 22 assumption is all rods in.
23 MEMBER MARCH-LEUBA: With the worst rod 24 stuck out you don't need to dilute boron. You go 25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.
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130 critical.
1 MEMBER CORRADINI: But the boron dilution 2
3 MEMBER MARCH-LEUBA: Boron dilution helps 4
you when you have all rods in.
5 MEMBER CORRADINI: Right, but in the 6
Chapter 15 analysis the worst rod stuck out was part 7
of the assumptions of the boron dilution question.
8 MEMBER MARCH-LEUBA: No, it was 9
10 MEMBER CORRADINI: I'm looking at the 11 Staff, I'm sure that's the case.
12 MEMBER MARCH-LEUBA: Worst rod is stuck 13 out, you go critical without diluting boron.
14 MS. KARAS: This is Becky Karas from 15 Reactor Systems. We are looking at all those 16 scenarios, you're right.
17 In Chapter 15 you would assume the worst 18 rod is stuck out and then we're looking at both end of 19 cycle with no boron conditions.
20 We're also looking to see if it's 21 potentially more limiting for a beginning-of-cycle or 22 minimal cycle condition with boron redistribution and 23 one rod stock out.
24 But as Ryan's explained, those are all to 25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.
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131 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br /> at this point, right? So, when you take an 1
all rods in condition and you want to go out for 2
extended periods of time, that hasn't been looked at 3
yet.
4 And you would get a lot of margin with the 5
one rod and you're using things like more nominal 6
assumptions, but that's one of the hurdles that we're 7
talking about.
8 MEMBER CORRADINI: But that's what I 9
thought Ryan was suggesting is requiring more analysis 10 potentially on both parts, on both sides.
11 MR. NOLAN: Yes, we would have to take a 12 closer look to go beyond 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br />.
13 MEMBER BLEY: And no one's willing to say 14 how much effort that is without looking at it.
15 MEMBER MARCH-LEUBA: To me the biggest 16 argument of what the Staff is saying is you don't want 17 to create a precedent that will then backfit all the 18 plans and they have to take longer.
19 MEMBER BLEY: You're already setting a bit 20 of a precedent in that you're analyzing something 21 that's not required at this stage.
22 MR. NOLAN: Yes, so let me add that I 23 believe every PWR has mitigating strategies for 24 reactivity control for adding borated water.
25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.
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132 So this is one of the first PWRs we're 1
seeing that does not have a strategy to do so, which 2
is why we're discussing the issue.
3 CHAIR REMPE: So, if I think about it, 4
they have a lot of NuScale-specific things but there's 5
also the fact that there's a philosophy about that if 6
you go to 14 days you don't have to have onsite FLEX, 7
which is more generic and hasn't really been discussed 8
very much.
9 Have you thought much about that part?
10 Because if you do that Phase 1, Phase 2, Phase 3, 11 that's what they're going for, they're going to still 12 have the safer stuff maybe with the COL Applicant.
13 But is that cast in concrete or what's your thoughts 14 on that?
15 MR. NOLAN: I guess for the operating 16 reactors it was more of a Phase 1 plus Phase 2 should 17 be at least 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br />, right? And then the assumption 18 is Phase 3, you'd get the offsite resources at 24 19 hours2.199074e-4 days <br />0.00528 hours <br />3.141534e-5 weeks <br />7.2295e-6 months <br />.
20 And so if your Phase 1 strategy is 21 sufficiently long, you don't need onsite portable 22 equipment. I think South Texas is a good example of 23 the three and four.
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133 equipment.
1 (Simultaneous speaking.)
2 CHAIR REMPE: Okay, so --
3 MR. NOLAN: But Phase 1 is sufficiently 4
long enough.
5 CHAIR REMPE: Okay, so basically this 6
isn't that unique that they're saying no flux on site.
7 MR. NOLAN: It would certainly be unique 8
for operating plants. It's probably more common than 9
not for new reactors.
10 MEMBER BLEY: I'm still stewing over your 11 precedent issue. I mean the whole Chapter 20 is 12 something that, as you said, isn't required for a 13 design cert.
14 The Applicant's asked you to review it and 15 you have. The Applicant's asked you to review it 16 beyond 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br />, which doesn't seem any more 17 precedent-setting than coming into do it for 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br /> 18 when you don't need to.
19 So, that argument seems a little fuzzy to 20 me. Think it over tonight and tell us more tomorrow.
21 MR. COYNE: Kevin Coyne, NRO. One thought 22 is we review against the regulatory requirement, not 23 against the criteria that an Applicant is giving us to 24 review against.
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134 So, we reviewed at 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br /> because we 1
believe that's what's necessary to meet the regulatory 2
requirement for the design features that are described 3
for the SSCs in the FSAR or will be.
4 So, going beyond that isn't necessary to 5
support the regulatory finding we need to make against 6
5150(5) for those portions that would get finality 7
with the design certification.
8 MEMBER CORRADINI: But what I heard you 9
say, Kevin, then is you were willing to take the first 10 step but the second step goes outside of the 11 regulatory requirements as stated.
12 That's what I'm -- in other words, you 13 reviewed what you eventually would have to review 14 anyway, you just did it earlier in the phasing.
15 But to go beyond 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br /> goes beyond what 16 the regulation requires.
17 MR. NOLAN: Goes beyond what we believe is 18 needed to satisfy the review that the design aspects 19 satisfy the regulation.
20 And reviewing a design cert application to 21 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br /> is not precedent-setting, it's what we did 22 for APR 1400.
23 MEMBER BLEY: But at the time we thought 24 you'd need to do it.
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135 MEMBER KIRCHNER: I'll just point out that 1
the advanced reactor policy statement expects better 2
performance out of these advanced plants.
3 So, you could actually use the 4
Commission's policy as a justification for looking out 5
further.
6 MEMBER BLEY: Let me just ask you where 7
you're headed. You've set the SECY up.
8 If the SECY doesn't generate an SRM or 9
it's what I was saying earlier, at some point it's by 10 default considered accepted, then that would agree 11 with your interpretation on the 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br />.
12 If the Commission finds that you ought to 13 look beyond that, they would issue an SRM I suppose.
14 So, you've kind of left it in the Commission's lap as 15 far as I understand what you've done with the SECY.
16 MEMBER KIRCHNER: That's a possibility.
17 CHAIR REMPE: Steve, did you want to say 18 something? We kept interrupting you.
19 MR. SCHULTZ: No, I got my question and 20 statements in, thank you.
21 CHAIR REMPE: Okay, so we may have a 22 closed meeting still. You don't want to talk anymore 23 in private?
24
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136 statements? But not your final ones. I'll go to 1
public comments unless you guys have any more 2
questions.
3 MEMBER BLEY: We just went around and 4
around on this but there's only, essentially, one open 5
item, right in your SER?
6 You didn't specifically talk open items 7
but I think there's only one and that has to do with 8
the boron dilution.
9 MEMBER CORRADINI: There is another one 10 formally which is the SECY.
11 CHAIR REMPE: The SECY is what I was 12 thinking of.
13 MEMBER CORRADINI: There's a process open 14 item 15 MEMBER BLEY: Yes, it does have it in 16 there. You're right, it's there.
17 CHAIR REMPE: Okay, so with that, could 18 you get the phone lines open and I'll ask if there are 19 any public comments in the audience while we're 20 waiting for the phone lines to be opened?
21 Seeing no one trying to talk on the mic, 22 we'll just wait. I heard a beep that implies to me 23 the phone lines are open.
24 Is anyone out there that could confirm 25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.
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137 that? I know we're not supposed to have to do that 1
anymore but it seems prudent.
2 Not hearing any comments and I'll wait for 3
Mike.
4 MEMBER CORRADINI: Is anyone out on the 5
open line, please?
6 CHAIR REMPE: Yes, but wait until after we 7
get through this line thing. Let's worked for Mike to 8
come back just to make sure I don't preclude someone 9
from the public wanting to --
10 MEMBER CORRADINI: If somebody's on the 11 public line could you please speak up?
12 CHAIR REMPE: I think I heard a voice so 13 I'm going to assume that there are no comments from 14 anyone on the phone line and we'll let the phone line 15 get back closed.
16 And I think I saw somebody who decided 17 they wanted to talk. Please state your name and 18 provide your comment.
19 MR. BERGMAN: Tom Bergman with NuScale.
20 So, I wasn't sure I was really considered 21 a member of the public but listening to the Staff's 22 discussion, I do agree they've taken an approach that 23 is sort of very efficient at getting to a finding.
24 As far as the 14 days, we would have 25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.
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138 preferred this paper, hearing that it's an info paper, 1
that it would be an actual vote paper because the 2
Commission stopped doing negative consent papers like 3
decades ago.
4 And whether or not it needs Commission 5
engagement is a Staff decision, but to me this is 6
unlike what we did with 5054(M), the licensed 7
operators rule, which only applies to licensees but we 8
chose to address it in the DC.
9 And we addressed it in a very different 10 way than it's done. And that has gone very well.
11 Obviously nothing's approved.
12 So we think they can go beyond 14 days but 13 the policy issue, potential policy issue, we saw is if 14 you can get to 14 days, that constitutes the word 15 indefinite.
16 That's what we are really proposing based 17 on the resources we need at 14 days, which we don't 18 need at 14 days, we really need much later, is a 19 gravity feedwater supply in the spent fuel pool.
20 But that's the hard question we're asking, 21 is if we can show we can get to 14 days, does that 22 constitute indefinite under the definition of a rule?
23 That's what we were seeking from the 24 Staff, not just a 14-day capacity because we show 50 25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.
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139 days. And the other question is why 14 days? And we 1
debated.
2 You want a technically defensible number, 3
right, you just don't want to pick 30 days or whatever 4
because why did you pick 30 days? And there were two 5
obvious technically defensible numbers to us.
6 One was 14 days which was based on the 7
ability for ad hoc response at Fukushima that grossly 8
exceeds what we need in our plant, and then 50 days.
9 The problem with 50 days is that sets a 10 very high bar for everybody else trying to come in.
11 And 50 days really wouldn't leave us any margin 12 because you always erode margin during construction in 13 operation.
14 But those were the two sort of technically 15 defensible days and we felt 14 represented a 16 reasonable number, not just for us but potentially for 17 other advanced reactors coming down the road.
18 MEMBER BLEY: Tom, would you restate -- if 19 we can get to 14 days, does that constitute --
20 (Simultaneous speaking.)
21 MR. BERGMAN: Basically indefinite coping.
22 MEMBER BLEY: Indefinite coping, right.
23 MR. BERGMAN: In terms of indefinite means 24 you're confident you can get supplies from off site to 25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.
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140 keep the plant in a safe condition indefinitely.
1 Because if you don't pick a day, then indefinite means 2
forever.
3 CHAIR REMPE: So, before I go around the 4
table, I want Mike to confirm the lines were open and 5
he closed them, right?
6 We heard someone mumble something but 7
there weren't any comments, but I'll give the public 8
one more time here on the phone line.
9 So, again I'll ask does anyone on the 10 phone line that's a member of the public want to make 11 a comment? And this time I'm still not hearing 12 everything.
13 I'm going to ask you to go ahead and close 14 them and we're going to go around the table and I'd 15 like the Members and our consultant to chime in about 16 their thoughts again to confirm they're comfortable 17 with trying to have a letter discussed this month at 18 the full Committee Meeting.
19 Again, our schedule, we've got a lot of 20 other letters that are in the queue so it may not 21 happen but my workload in the next couple of days will 22 depend on your response back.
23 And then if you have some comments you'd 24 like to have emphasized, state them here and then I 25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.
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141 probably will say send me an email with them written 1
down too.
2 Because I'm trying to update a very drafty 3
letter. And I'm going to start with Steve, our 4
consultant, and then I'll go around the table, okay?
5 MR. SCHULTZ: I appreciate all the 6
comments in the discussions that we had today from 7
both the Applicant and the Staff.
8 My understanding has gone back and forth 9
even through the discussion period here.
10 I feel that based on the comments, based 11 on all the work that the Staff has done to prepare the 12 SECY as well as the documentation associated with 13 staging what I think their findings will be, I think 14 we have enough, I think the Committee has enough, to 15 write an interim letter.
16 I'm not sure what the final thoughts will 17 be from the Committee but I think based on what we've 18 heard today we can formulate a statement of where the 19 progress stands and where we expect it to go forward.
20 I think I got the timeframe right, the 21 next six months, associated with the Chapter 15 22 evaluations and so forth that need to be completed.
23 It's got to be interim because of the need 24 to determine whether the findings for Chapter 15 are 25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.
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142 going to influence this.
1 CHAIR REMPE: I think definitely the 2
Chapter 15 findings are important.
3 I guess the other thing is if there's 4
anything during our discussions today that ACRS 5
identified that the Staff has not already identified, 6
those are that kind of points too that I'd really like 7
to have.
8 I can I hope summarize the status of 9
things but if there's some gaps in what they're 10 reviewing that are not being adequately addressed, let 11 me know or send me some thoughts, okay?
12 MR. SCHULTZ: I think based on what we're 13 doing on this topic, the difficulty is this topic has 14 got constraints that are different from the Chapter 15 15 analysis and constraints.
16 But the Staff has spoken to that today so 17 that needs to be done. But given the combination of 18 letters that are going to be written for this meeting, 19 I think we have several positions to put forward.
20 CHAIR REMPE: Thank you. Dick?
21 MEMBER SKILLMAN: I think we can write a 22 letter that agrees with NuScale and the Staff that the 23 concept of 14 days is sufficient to be described as 24 indefinite. I'm comfortable with that.
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143 There are some features of the NuScale 1
design that I'm not comfortable with but on this 2
particular one, I can concur that 14 days is a 3
timespan that can be defended as indefinite.
4 Just two things based on the Fukushima 5
experience, like the team that presented. After about 6
9, 10, 11 days in spite of the horrible infrastructure 7
challenges, the teams at Fukushima were able to add 8
water and do a lot of things.
9 14 days after TMI-2 would have put that 10 event in April 11th of '79. By that time we were 11 cooling down. We had a mess but the containment was 12 intact, we were adding water, we were steaming using 13 bypasses on the feedwater isolation valves.
14 Clearly we were in the middle of a 15 catastrophe. The aggregate intellect and ingenuity of 16 the team, even without procedures and no emergency 17 planning, pulled it together.
18 This design is so much more advanced with 19 so much more defense in depth, I think we can say yes, 20 14 days constitutes the front end of indefinite and 21 after that they can keep on going.
22 So, I'm comfortable with that.
23 CHAIR REMPE: You're basically also then 24 implying you think the Staff should go a bit further 25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.
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144 in their review than 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br />.
1 MEMBER SKILLMAN: Yes.
2 CHAIR REMPE: Okay, that kind of input is 3
also helpful on how I write this letter since it's a 4
group letter and I don't want to have a minority 5
opinion when I present.
6 Mike, go ahead?
7 MEMBER CORRADINI: So, I guess I agree 8
with Dick and I think Steve but I'm going to go a 9
little bit further. It seems to me we've got to take 10 a holistic approach to this.
11 So, if we're going to go beyond three 12 days, then I need some action after three days to 13 settle other issues that I'm worried about. And that 14 issue is that I want to make sure that I'm subcritical 15 after a few days.
16 So, I'm going to pretend that I'm in 17 charge. If I were in charge and I would say NuScale, 18 I'll grant you 14 days but at 3 days I want you to go 19 make sure you're subcritical somehow -- I don't care 20 how, you figure it out -- that's got to be in the 21 letter.
22 Otherwise we stop at 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br />. That's it.
23 CHAIR REMPE: Matt? Okay.
24 MEMBER SUNSERI: I don't have anything 25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.
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145 else to add technically and I would support an interim 1
letter.
2 CHAIR REMPE: Pete?
3 MEMBER RICCARDELLA: Ditto exactly what 4
Matt said.
5 CHAIR REMPE: Okay, Walt?
6 MEMBER KIRCHNER: Again, I'll just repeat 7
myself. There is an advanced reactor policy statement 8
and the expectation is that these advanced designs do 9
have significant margin beyond the current fleet.
10 So, going back and just falling back on 11 the existing fleet, I'm in the camp of both Dick and 12 Mike. Yes, you need to look at assurances about the 13 subcriticality, so that gets into boron kind of 14 issues.
15 But that aside, when you think of the 16 Chapter 15 analysis and the complexity of doing that 17 versus just looking at this massive heat sink, I'm 18 pretty confident this is like a first law of 19 thermodynamics calculation.
20 This is not a dynamic complicated systems 21 code kind of analysis of a LOCA or something very 22 difficult and challenging. So, I'm pretty confident 23 that they can go out to 14 days with what information 24 we've seen.
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146 And the caveat would, again, be in my mind 1
whether we have too many to control.
2 So, thank you.
3 MEMBER SKILLMAN: Can I just take my note 4
back? I'm so glad Walt used that word.
5 I'm surprised at critical safety function, 6
and this goes back to NEI 0612, why reactivity control 7
isn't one of the critical safety functions.
8 Why isn't reactivity control one of the 9
critical safety functions? That's the reservation I 10 had and Mike nipped it in the bud.
11 I just don't understand why those words 12 don't show up. They're kind of the fundamental law we 13 all hang onto for respecting the technology.
14 You can really shut one of these things 15 down and keep it down.
16 CHAIR REMPE: And as you pointed out 17 earlier, you need some instrumentation to assure that.
18 Go ahead, Jose.
19 MEMBER MARCH-LEUBA: I was going to say I 20 agree with Mike that reactivity control is a key issue 21 because the very difficult problem that we still have 22 to solve is the boron call it dilution or 23 redistribution.
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147 are distilling water and filling up the containment 1
with cold, unborated water, which eventually makes it 2
into the downcomer and the downcomer is going to be 3
cold, unborated water.
4 Because technically the boron inside the 5
core or maybe on the rise and you're feeding cold, 6
unborated water through the bottom of the vessel.
7 Now, the probability that that happens and 8
goes critical is 10 to the minus 25 because something 9
would happen that would prevent it. But you have to 10 analyze it and you have to ensure that does happen.
11 And one thing is doing a normal ECCS 12 actuation after an accident where you will be in that 13 operation for two or three hours and then you flag the 14 containment.
15 And another thing is, well, I want to stay 16 five months in this condition. It's stealing my boron 17 away and this obsession with passive operation and 18 hands-off is leading us into the wrong direction.
19 I think we should be reviewing emergency 20 operating guidelines, not the procedures, but 21 guidelines that direct the operators to flood the 22 containment with 2000 PPM water and then nothing 23 happens.
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148 to an operator or an engineer from NuScale it's 1
nothing would happen, nothing would happen, that 2
cannot happen. And it's going into the same 3
direction.
4 You guys should be thinking what could 5
possibly go wrong? And I don't see the NuScale Staff 6
thinking what could possibly go wrong. What can my 7
operators do to make it better?
8 Instead of, yes, obsession with passive 9
thinking is marketing. But it's not safe. The only 10 thing saving us is that this is an extremely safe 11 reactor.
12 CHAIR REMPE: Okay, thank you. Dennis?
13 MEMBER BLEY: I think we can write a 14 letter. I think I'd like to us to have a little 15 private time to talk about the 14 days, although I 16 don't see any problem with it.
17 But I think we want to hash that out 18 because I think the Commission will -- that will be 19 the main thing they look at in this letter.
20 CHAIR REMPE: Let me explore, you mean 21 today? You'd like to have us stay and talk a bit 22 more?
23 MEMBER BLEY: We can go into letter 24 writing but a closed session first to talk about that.
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149 CHAIR REMPE: That can be worked on.
1 Vesna?
2 MEMBER DIMITRIJEVIC: I express the same 3
sentiment. We should be look at those 14 days and 4
does that mean indefinite? And that's it basically.
5 I think we should write the letter, maybe 6
we can even have a private session now because we're 7
finishing.
8 CHAIR REMPE: Okay, so I agree with what 9
everyone said but I'd like to still elaborate both 10 with this thing about criticality as well as the 11 guides for the operators requires assurance that the 12 instrumentation is there.
13 And that really is the only thing I could 14 add to what's been said. I was going to suggest and 15 I was trying to draft this letter up, half of it is 16 the standard boilerplate that you put on every single 17 NuScale letter, Mike.
18 And so why don't we just stick the stuff 19 on Chapter 20 in with the other parts of this NuScale 20 we're going to be reviewing and writing on this month.
21 I know Mike's saying no, he still wants it separate.
22 If we have to have the separate session, 23 Dennis, then that would be a reason to having the 24 separate letter.
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150 But I'd also, because I'm trying to draft 1
the thing, I sure would like to have that session 2
today and have us discuss it before we go to the full 3
Committee just so that I'll have more time to digest 4
it.
5 And so I think that I would like to 6
request the Members to stay here after we close.
7 MEMBER MARCH-LEUBA: Can we go around the 8
table and see if anybody wants a closed session?
9 CHAIR REMPE: For right now?
10 MR. SNODDERLY: This is Mike Snodderly 11 from ACRS Staff. So, please recall our letter-writing 12 we want to have in open session.
13 I think the basis we have for going closed 14 is the OUO aspect of the SECY paper and the fact that 15 it is not being released publicly until July 12th.
16 So, what I would suggest is that we do go 17 into a closed session here at this time to discuss the 18 OUO aspect, the aspect that was set. And any 19 deliberations you want to have concerning that and 20 possible response to that.
21 CHAIR REMPE: Okay, so if we do that, 22 again, I'm not ready to do that because there's one 23 other thing I want to talk -- before we go to closed 24 session, I just want to answer something with the 25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.
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151 Staff.
1 MR. SNODDERLY: That's if we're going to 2
closed for the letter-writing.
3 CHAIR REMPE: Okay, and then we would not 4
have the transcriber stay or they should stay and 5
record it? What should happen on that?
6 MR. SNODDERLY: If you do it and the 7
transcriber's here we should go closed and it should 8
be transcribed. If you don't want to do it today 9
then, yes, we can do it tomorrow.
10 CHAIR REMPE: Okay, so we'll do that. The 11 other thing that the Staff brought up is what do you 12 want us to talk about?
13 And there will be limited time and I think 14 it might be good for us to comment on that too. I 15 think the Staff's slides I didn't see any big changes 16 but clearly, NuScale will not have time to go through 17 as much depth tomorrow as they've done today.
18 MEMBER CORRADINI: Well, I mean my opinion 19 is given the fact that we can educate our lone Member, 20 they can essentially shrink it down but we'll get to 21 the key points.
22 We've now asked them everything we can so 23 if we're quiet, they can get through it in 15 minutes 24 in both cases.
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152 CHAIR REMPE: Okay, so they have, what is 1
it, 25, 28 slides? They still need to reduce it a 2
bit.
3 MEMBER CORRADINI: But they're smart, they 4
can figure it out. I think we clarified a whole bunch 5
of things today that we won't necessarily need to 6
reclarify tomorrow, assuming we can remember.
7 That's my way of looking at it.
8 CHAIR REMPE: From my viewpoint, I think 9
our letter will be focusing on the mitigation of 10 beyond-design-basis rule and how it's being met.
11 The LOLA is of less controversial -- I 12 don't think it's a big deal other than it's there 13 right now. Frankly, the other two sections are going 14 to be going away so I don't see any reason for us to 15 comment much on those too.
16 So, they could clearly focus on that too 17 and eliminate the other discussion. So, with that, 18 we're going to go into closed session. You want to 19 take a break too? Let's say for ten minutes. Okay, 20 thank you.
21 (Whereupon, the above-entitled matter went 22 off the record at 4:00 p.m.)
23 24 25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.
(202) 234-4433 WASHINGTON, D.C. 20005-3701 (202) 234-4433
LO-0719-66168 NuScale Power, LLC 1100 NE Circle Blvd., Suite 200 Corvallis, Oregon 97330 Office 541.360-0500 Fax 541.207.3928 www.nuscalepower.com July 3, 2019 Docket No.52-048 U.S. Nuclear Regulatory Commission ATTN: Document Control Desk One White Flint North 11555 Rockville Pike Rockville, MD 20852-2738
SUBJECT:
NuScale Power, LLC Submittal of Presentation Materials Entitled ACRS Subcommittee Presentation, NuScale FSAR Chapter 20, Mitigation of Beyond-Design-Basis Events, PM-0719-66189, Revision 0 The purpose of this submittal is to provide presentation materials for use during the upcoming Advisory Committee on Reactor Safeguards (ACRS) NuScale Subcommittee meeting on July 9, 2019. The materials support NuScales presentation of Chapter 20, Mitigation of Beyond-Design-Basis Events, of the NuScale Design Certification Application.
The enclosure to this letter is the nonproprietary presentation entitled ACRS Subcommittee Presentation, NuScale FSAR Chapter 20, Mitigation of Beyond-Design-Basis Events, PM-0719-66189, Revision 0.
This letter makes no regulatory commitments and no revisions to any existing regulatory commitments.
If you have any questions, please contact Nadja Joergensen at 541-452-7338 or at njoergensen@nuscalepower.com.
Sincerely, Zackary W. Rad Director, Regulatory Affairs NuScale Power, LLC Distribution: Robert Taylor, NRC, OWFN-7H4 Michael Snodderly, NRC, TWFN-2E26 Gregory Cranston, NRC, OWFN-8H12 Samuel Lee, NRC, OWFN-8H12 Omid Tabatabai, NRC, OWFN-8H12
Enclosure:
ACRS Subcommittee Presentation, NuScale FSAR Chapter 20, Mitigation of Beyond-Design-Basis Events, PM-0719-66189, Revision 0
LO-0719-66168 NuScale Power, LLC 1100 NE Circle Blvd., Suite 200 Corvallis, Oregon 97330 Office 541.360-0500 Fax 541.207.3928 www.nuscalepower.com
Enclosure:
ACRS Subcommittee Presentation, NuScale FSAR Chapter 20, Mitigation of Beyond-Design-Basis Events, PM-0719-66189, Revision 0
Copyright 2019 by NuScale Power, LLC.
Revision: 0 Template #: 0000-21727-F01 R5 NuScale Nonproprietary ACRS Subcommittee Presentation July 9, 2019 NuScale FSAR Chapter 20 Mitigation of Beyond-Design-Basis Events
Copyright 2019 by NuScale Power, LLC.
Revision: 0 Template #: 0000-21727-F01 R5 Presenters Chris Maxwell Senior Reactor Operator Zack Rad Director, Regulatory Affairs Nadja Joergensen Licensing Specialist
Copyright 2019 by NuScale Power, LLC.
Revision: 0 Template #: 0000-21727-F01 R5 Mitigation Strategies for Beyond-Design-Basis External Events 10 CFR 50.155(b)(1)
Copyright 2019 by NuScale Power, LLC.
Revision: 0 Template #: 0000-21727-F01 R5 Objective of MBDBE Rule
- Establish coping capabilities to prevent damage to fuel in any NPM and the SFP, and to maintain containment function by using plant and mitigating equipment during an extended loss of AC power (ELAP) concurrent with a loss of normal access to the normal heat sink (LUHS).
- Key safety functions (core cooling, containment, spent fuel pool cooling) are established and maintained indefinitely, or until sufficient site functional capabilities can be maintained without the need for mitigation strategies.
Copyright 2019 by NuScale Power, LLC.
Revision: 0 Template #: 0000-21727-F01 R5 Indefinite Coping
- indefinitely, or until sufficient site functional capabilities can be maintained without the need for mitigation strategies
- Means to plan for obtaining sufficient resources to maintain the three key safety functions until an alternate means of removing heat is established
- Allows new reactors to establish different approaches from those of operating reactors including using only installed plant equipment for both the initial and long-term response
- Alternate means of removing heat may be provided by installed plant equipment.
Copyright 2019 by NuScale Power, LLC.
Revision: 0 Template #: 0000-21727-F01 R5 Indefinite Coping
- NuScale considers a minimum coping period of 14 days using only installed plant equipment to be sufficient time to establish alternate means of removing heat.
- In the Fukushima Daiichi accident, without pre-planning or a hardened pool makeup connection, and with limited access to off-site resources, personnel began
- adding water to the Unit 4 SFP with fire and concrete pump trucks after 9 days; and
- injecting water via the fuel pool cooling system at 14 days.
- Beyond minimum installed equipment coping period, the continued use of installed plant equipment, ad hoc resources, and equipment repairs can be used to continue coping indefinitely.
Copyright 2019 by NuScale Power, LLC.
Revision: 0 Template #: 0000-21727-F01 R5 NuScale Coping Capability
Copyright 2019 by NuScale Power, LLC.
Revision: 0 Template #: 0000-21727-F01 R5 NuScale Power Plant Design
- The NuScale Power Plant was designed to provide coping during an ELAP concurrent with a LUHS without:
- Inventory addition
- Supplemental equipment
- Off-site resources
- Operator action (monitoring)
- Extended coping duration is provided by the automatic response of installed plant equipment alone.
- This strategy permits plant staff to focus on addressing the initiating event and restoring normal functional capabilities.
Copyright 2019 by NuScale Power, LLC.
Revision: 0 Template #: 0000-21727-F01 R5 Baseline Coping Capability Criteria, Conditions, and Assumptions
- 1. Plant equipment that is designed to be robust with respect to design basis external events is assumed to be fully available.
- 2. Plant equipment that is not robust is assumed to be unavailable.
- 3. Procedures and equipment relied upon should ensure that satisfactory performance of necessary fuel cooling and containment functions are maintained.
- 4. The fuel in the modules is required to remain covered at all times.
- 5. The fuel in the SFP is required to remain covered at all times.
PM-0719-66189 10 Copyright 2019 by NuScale Power, LLC.
Revision: 0 Template #: 0000-21727-F01 R5 Boundary Conditions
- 1. Beyond-design-basis external event occurs impacting all modules at the site.
- 2. All modules on-site initially operating at power, unless site has procedural direction to shut down due to the impending event.
- 3. Each module is successfully shut down when required (i.e., all rods inserted, no anticipated transient without scram).
- 4. On-site staff is at site administrative minimum shift staffing levels.
- 5. No independent, concurrent events, e.g., no active security threat.
- 6. All personnel on-site are available to support site response.
- 7. Spent fuel in dry storage is outside the scope of the event.
PM-0719-66189 11 Copyright 2019 by NuScale Power, LLC.
Revision: 0 Template #: 0000-21727-F01 R5 NuScale Power Plant Response Plant response without operator action or off-site resources 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br />
- DHRS initiation
- Containment isolation ECCS initiation 4
months 5
months SFP level -
Top of fuel 5
days Installed plant safety systems
- Passive core cooling
- Passive containment heat removal
Weir bottom 30 days 50 days UHS level -
45
PM-0719-66189 12 Copyright 2019 by NuScale Power, LLC.
Revision: 0 Template #: 0000-21727-F01 R5 Core Cooling
- Reactor coolant system inventory is preserved by containment isolation.
- DHRS passively removes decay heat for the first 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br />.
- Modules are partially immersed in the reactor pool, which is part of the UHS.
- Passive heat removal to the UHS maintains core cooling for more than 50 days without pool inventory makeup or operator action.
PM-0719-66189 13 Copyright 2019 by NuScale Power, LLC.
Revision: 0 Template #: 0000-21727-F01 R5 Containment
- Containment isolation valves (CIVs) and the CNV provide passive containment function. Without operator action or electrical power, the safetyrelated CIVs close to isolate the CNV.
- Heat removal to the UHS passively controls temperature and pressure to ensure containment integrity. Peak pressure and temperature conditions for the CNV occur early in the event when the ECCS valves open and do not challenge containment integrity.
- Containment cooling is maintained for more than 50 days without pool inventory makeup or operator action.
PM-0719-66189 14 Copyright 2019 by NuScale Power, LLC.
Revision: 0 Template #: 0000-21727-F01 R5 Spent Fuel Pool Cooling
- The Spent Fuel Pool is part of the UHS.
- The Spent Fuel Pool is partially separated from the Refuel and Reactor Pools by the Weir Wall.
Weir Wall
PM-0719-66189 15 Copyright 2019 by NuScale Power, LLC.
Revision: 0 Template #: 0000-21727-F01 R5 Spent Fuel Pool Cooling
- The SFP, as part of the UHS, communicates with the refueling pool and reactor pool above the SFP weir wall.
As such, the pools respond as a single volume during an ELAP until UHS level lowers below the opening in the weir wall.
- The UHS inventory maintains passive cooling of the spent fuel in the SFP for more than 150 days following initiation of an ELAP without pool inventory makeup or operator action.
PM-0719-66189 16 Copyright 2019 by NuScale Power, LLC.
Revision: 0 Template #: 0000-21727-F01 R5 Monitoring
- No operator action is required to establish or maintain the required safety functions for more than 50 days following the onset of an ELAP. Therefore, no instrumentation is necessary to support operator actions.
- However, instrumentation and DC electrical power are provided to allow the Control Room Operators to observe the response of installed plant equipment and verify the conditions necessary for coping have been established.
- Indications remain available for a minimum of 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br />.
PM-0719-66189 17 Copyright 2019 by NuScale Power, LLC.
Revision: 0 Template #: 0000-21727-F01 R5 Spent Fuel Pool Monitoring 10 CFR 50.155(e)
PM-0719-66189 18 Copyright 2019 by NuScale Power, LLC.
Revision: 0 Template #: 0000-21727-F01 R5 Objective of SFPLI Rule
- Provide a reliable means to remotely monitor wide-range SFP water level until 5 years have elapsed since all of the fuel within that SFP was last used in a reactor vessel for power operation.
PM-0719-66189 19 Copyright 2019 by NuScale Power, LLC.
Revision: 0 Template #: 0000-21727-F01 R5 Spent Fuel Pool Level Indication
- The UHS system includes remote level indication for the following:
- Reactor Pool
- Refueling Pool
- Spent Fuel Pool (2)
- Normally powered by the highly reliable DC power system via the plant protection system.
- Include a replaceable battery power source, independent from the plant AC and DC power systems, with a minimum capacity of 14 days.
PM-0719-66189 20 Copyright 2019 by NuScale Power, LLC.
Revision: 0 Template #: 0000-21727-F01 R5 Conclusion
- NuScale Power Plant Mitigation Strategy
- Rely on the automatic response of permanently installed, safety-related plant equipment to establish and maintain the three key safety functions and provide extended coping capabilities of greater than 14 days.
- The NuScale Power Plant mitigation strategy does not require:
- Inventory addition
- Operator action
- NuScale SFPLI Strategy
- Installed instrumentation with 14 day battery backup power supply.
PM-0719-66189 21 Copyright 2019 by NuScale Power, LLC.
Revision: 0 Template #: 0000-21727-F01 R5 Portland Office 6650 SW Redwood Lane, Suite 210 Portland, OR 97224 971.371.1592 Corvallis Office 1100 NE Circle Blvd., Suite 200 Corvallis, OR 97330 541.360.0500 Rockville Office 11333 Woodglen Ave., Suite 205 Rockville, MD 20852 301.770.0472 Charlotte Office 2815 Coliseum Centre Drive, Suite 230 Charlotte, NC 28217 980.349.4804 Richland Office 1933 Jadwin Ave., Suite 130 Richland, WA 99354 541.360.0500 Arlington Office 2300 Clarendon Blvd., Suite 1110 Arlington, VA 22201 London Office 1st Floor Portland House Bressenden Place London SW1E 5BH United Kingdom
+44 (0) 2079 321700 http://www.nuscalepower.com Twitter: @NuScale_Power
PM-0719-66189 22 Copyright 2019 by NuScale Power, LLC.
Revision: 0 Template #: 0000-21727-F01 R5 Supplemental Slides (Description of slide 10)
PM-0719-66189 23 Copyright 2019 by NuScale Power, LLC.
Revision: 0 Template #: 0000-21727-F01 R5 NuScale Power Plant Response
- NuScale Power Module response within the first minute of the loss of all AC power and without operator action:
- Decay Heat Removal System initiation
- Containment isolation
- ECCS automatically initiates after 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br />.
- With the reactor shutdown and passive decay heat removal established, safe shutdown conditions are established.
- Decay heat passively transferred to the UHS.
PM-0719-66189 24 Copyright 2019 by NuScale Power, LLC.
Revision: 0 Template #: 0000-21727-F01 R5 NuScale Power Plant Response
- With UHS level greater than or equal to 45, core cooling and the containment function are maintained. It requires more than 50 days for UHS level to lower to this point.
- Without any addition of inventory, Spent Fuel Pool level would:
- Fall below the UHS weir after more than 4 months.
- Reach the top of spent fuel after more than 5 months.
PM-0719-66189 25 Copyright 2019 by NuScale Power, LLC.
Revision: 0 Template #: 0000-21727-F01 R5 NuScale Power Plant Response
Preliminary Safety Evaluation with Open Items: Chapter 20, Mitigation of Beyond-Design-Basis Events NuScale Design Certification Application ACRS Subcommittee Meeting July 9, 2019
Agenda
- NRC Staff Review Team
- Background
- Staffs Review Approach
- Summary of the Staffs (Preliminary) Findings
- Staff Review of NuScales MBDBE strategy
- Phase 4 Review Plan
- Abbreviations July 9, 2019 2
NRC Staff Review Team Key Technical Reviewers Clint Ashley, NRO Robert Vettori, NRO Ryan Nolan, NRO Michelle Hart, NRO Nan (Danny) Chien, NRO Nick Hansing, NRO Raul Hernandez, NRO John Budzynski, NRO Chang Li, NRO BP Jain, NRO Don Palmrose, NRO Matt McConnell, NRR Sheila Ray, NRR Dinesh Taneja, NRR Joe Ashcraft, NRR Amanda Marshall, NSIR Dan Barss, NSIR Project Management Omid Tabatabai, NRO July 9, 2019 3
=
Background===
10/30/2018: NuScale submitted its DCA, Rev 2 01/24/2019: NRC approved Final MBDBE Rule (10 CFR 50.155) 03/28/2019: NuScale informed the staff that it was revising its Ch. 20 06/10/2019: NuScale submitted revised Ch. 20 06/14/2019: NuScale submitted Rev. 1 to ELAP Technical Report 06/26/2019: NRC issued Information SECY 19-00661 07/12/2019: SECY 19-0066 will be publicly available (ML19148A443)
September 2019: 10 CFR 50.155 is expected to be publicly available 1SECY 19-0066: Staff Review of NuScale Power's Mitigation Strategy for Beyond-Design-Basis External Events July 9, 2019 4
Staffs Phase 2 Review Approach Staffs (preliminary) Phase 2 SER for Chapter 20 is based on Rev. 2 of NuScales DCA Staffs regulatory bases for the review consisted of:
Commission Orders EA-12-049 and EA-12-051 JLD-ISG-2012-01, Rev. 1 NEI 12-02, Rev. 1, NEI 12-06, Rev. 2 SRM-SECY-12-0025 SRM-SECY-16-0142 Based on the docketed information, the Staffs findings in Phase 2 SER are limited to the first 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br /> after initiation of a BDBE.
July 9, 2019 5
Summary of the Staffs (Preliminary) Findings 20.1: Mitigation Strategies for BDBE - detailed discussions in the upcoming slides 20.2: Loss of Large Area (LOLA)
Staff used SRP Section 19.4 as the guidance document Use of NEI 06-12 acceptable to staff to show compliance with 50.54(hh)(2)
Key safety functions for evaluation:
- RCS inventory/heat removal
- Containment isolation/integrity
- Release mitigation Staff finds NuScale design meets requirements of 50.54(hh)(2) 20.3: Emergency Procedures This Section will be reviewed during a combined license application review 20.4: Enhanced Emergency response capabilities for BDBE This Section will be reviewed during a combined license application review July 9, 2019 6
Staff Review of NuScales MBDBE strategy Regulatory Framework The recently approved regulation, 10 CFR 50.155, for mitigation of beyond-design-basis events (MBDBE) does not apply to applicants for a design certification.
NuScale is voluntarily seeking the NRCs approval of its proposal to use installed design features to mitigate beyond-design-basis external events.
NuScale design incorporates several design features that provide enhanced capabilities for mitigating an extended loss of ac power compared to currently operating reactors.
July 9, 2019 7
Regulatory Framework (Contd)
TEXT OF 10 C.F.R. § 50.155(b), (c), and (e) APPROVED BY THE COMMISSION (b) Strategies and guidelines. Each applicant or licensee shall develop, implement, and maintain:
(1) Mitigation strategies for beyond-design-basis external events. Strategies and guidelines to mitigate beyond-design-basis external events from natural phenomena that are developed assuming a loss of all ac power concurrent with either a loss of normal access to the ultimate heat sink or, for passive reactor designs, a loss of normal access to the normal heat sink. These strategies and guidelines must be capable of being implemented site-wide and must include the following:
(i) Maintaining or restoring core cooling, containment, and spent fuel pool cooling capabilities; and (ii) The acquisition and use of offsite assistance and resources to support the functions required by paragraph (b)(1)(i) of this section indefinitely, or until sufficient site functional capabilities can be maintained without the need for the mitigation strategies.
(c) Equipment. (1) The equipment relied on for the mitigation strategies and guidelines required by paragraph (b)(1) of this section must have sufficient capacity and capability to perform the functions required by paragraph (b)(1) of this section.
(2) The equipment relied on for the mitigation strategies and guidelines required by paragraph (b)(1) of this section must be reasonably protected from the effects of natural phenomena that are equivalent in magnitude to the phenomena assumed for developing the design basis of the facility.
(e) Spent fuel pool monitoring. In order to support effective prioritization of event mitigation and recovery actions, each licensee shall provide reliable means to remotely monitor wide-range water level for each spent fuel pool at its site until 5 years have elapsed since all of the fuel within that spent fuel pool was last used in a reactor vessel for power generation.
SRM-M190124A, Enclosure 1, Federal Register Notice at 140-41.
July 9, 2019 8
Staffs Review of NuScale MBDBE Approach (Contd)
NuScale MBDBE Approach Core cooling, containment, and spent fuel pool cooling is maintained by permanently installed SSCs
- MPS, DHRS, EDSS, ECCS, CNV, UHS, etc.
Minimum coping duration of 14 days
- Provides sufficient time for the licensee to establish an alternate means of removing heat No reliance on monitoring for the mitigation strategies
- Although instrumentation powered by the EDSS is expected to remain available in the near-term, module and reactor pool monitoring is a supplementary capability.
July 9, 2019 9
Staffs Review Approach Maintain consistency with scope of review performed for operating reactors and other design certifications.
- Focus on the initial response coping period (first 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br />) where the most critical and time-sensitive actions are projected to occur.
Verify the design capabilities and capacities of the permanently installed SSCs satisfy the required safety functions, including the effects of credible transient phenomena, for 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br /> following initiating event.
- Review will focus on design aspects of SSCs as described in the FSAR.
- Operational aspects (e.g., procedures, training) deferred to COL stage.
July 9, 2019 10 Staffs Review of NuScale MBDBE Approach (Contd)
COL applicant would need to describe how mitigating strategies (or sufficient site functional capabilities) are maintained for an indefinite time period.
- SSC design aspects would only need to be addressed if there are credible transient phenomena (e.g., return to power) that could challenge core cooling, containment, or SFP cooling beyond 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br />
- Level of detail expected is commensurate with time available to implement actions.
Staff plans to document that instrumentation is not relied on to support the mitigation strategies; however:
- Instrumentation is expected to be available for the initial 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br />,
- Pool level instrumentation is provided with batteries, for an additional 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br /> of level monitoring, and
- Provides additional assurance that systems have responded as designed.
July 9, 2019 11 Staffs Review Approach (Contd)
Phase 4 Review Plan The staff will follow its plans, as described in SECY 19-0066, to complete its review of NuScales Ch. 20 in Phase 4 of the DCA review.
The Staff will evaluate NuScales DCA, Rev. 3, information for compliance with the requirements of 10 CFR 50.155 NuScale DCA, Rev. 3, is expected to be submitted in late August 2019 Staffs ACRS Full Committee presentation is scheduled for July 10, 2019.
July 9, 2019 12
ACRS Advisory Committee on Reactor Safeguards CFR Code of Federal Regulations CNV Containment Vessel COL Combined License BDBA Beyond-Design-Basis Accident CNV Containment Vessel DCA Design Certification Application DHRS Decay Heat Removal System ECCS Emergency Core Cooling System EDSS Highly Reliable Electrical System ELAP Extended Loss of AC Power FSAR Final Safety Analysis Report JLD NRC Japan Lessons Learned Directorate MBDBE Mitigation of Beyond-Design-Basis Events MPS Module Protection System NEI Nuclear Energy Institute NRC Nuclear Regulatory Commission NRR NRC Office of Nuclear Reactor Regulation NSIR NRC Office of Nuclear Security and Incident Response NRO NRC Office of New Reactors SER Safety Evaluation Report SRM Staff Requirement Memorandum UHS Ultimate Heat Sink Abbreviations July 9, 2019 13