ML20352A478

Transcript of the Advisory Committee on Reactor Safeguard 681st Full Committee Meeting - December 1, 2020, Pages 1-99 (Open)

ML20352A478
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Issue date:	12/01/2020
From:	Advisory Committee on Reactor Safeguards
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Burkhart, L, ACRS
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NRC-1258
Download: ML20352A478 (99)

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Official Transcript of Proceedings NUCLEAR REGULATORY COMMISSION

Title:

Advisory Committee on Reactor Safeguards Open Session Docket Number:

(n/a)

Location:

teleconference Date:

Tuesday, December 1, 2020 Work Order No.:

NRC-1258 Pages 1-59 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 681ST MEETING 4

ADVISORY COMMITTEE ON REACTOR SAFEGUARDS 5

(ACRS) 6

+ + + + +

7 OPEN SESSION 8

+ + + + +

9 TUESDAY 10 DECEMBER 1, 2020 11

+ + + + +

12 The Advisory Committee met via Video-13 Teleconference, at 2:00 p.m. EST, Matthew W. Sunseri, 14 Chairman, presiding.

15 16 COMMITTEE MEMBERS:

17 MATTHEW W. SUNSERI, Chairman 18 JOY L. REMPE, Vice Chairman 19 WALTER L. KIRCHNER, Member-at-large 20 RONALD G. BALLINGER, Member 21 DENNIS BLEY, Member 22 CHARLES H. BROWN, JR. Member 23 VESNA B. DIMITRIJEVIC, Member 24 JOSE MARCH-LEUBA, Member 25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.

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2 DAVID A. PETTI, Member 1

PETER RICCARDELLA, Member 2

3 ACRS CONSULTANT:

4 MICHAEL CORRADINI 5

STEVE SCHULTZ 6

7 DESIGNATED FEDERAL OFFICIAL:

8 ZENA ABDULLAHI 9

10 ALSO PRESENT:

11 MICHAEL DUDEK, NRR 12 DAVID H. HINDS, GE-Hitachi 13 MARIELIZ JOHNSON, NRR 14 SCOTT MOORE, Executive Director, ACRS 15 NOLAN RYAN, NRR 16 GEORGE WADKINS, GE-Hitachi 17 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 AGENDA 1

Item Page 2

Opening Remarks by the ACRS Chairman 5

3 BWRX-300 Topical Report NEDC-33912, 4

Reactivity Control 5

Remarks from the Subcommittee Chairman 7

6 Presentation and discussion 7

NRC staff, Michael Dudek 8

8 GE-Hitachi, George Wadkins and David Hinds 9

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4 P R O C E E D I N G S 1

2:01 p.m.

2 CHAIR SUNSERI: Meeting will now come to 3

order. This is the first day of the 681st meeting of 4

the Advisory Committee on Reactor Safeguards.

5 I'm Matthew Sunseri, Chair of the ACRS.

6 And I now call the roll to confirm communications and 7

that a quorum exists. I'll start with Ron Ballinger.

8 Dennis Bley.

9 MEMBER BLEY: Here.

10 CHAIR SUNSERI: Charles Brown.

11 MEMBER BROWN: Here.

12 CHAIR SUNSERI: Vesna Dimitrijevic.

13 MEMBER DIMITRIJEVIC: Here.

14 CHAIR SUNSERI: Walt Kirchner.

15 MEMBER KIRCHNER: Here.

16 CHAIR SUNSERI: Jose March-Leuba.

17 MEMBER MARCH-LEUBA: Present.

18 CHAIR SUNSERI: Dave Petti.

19 MEMBER PETTI: Here.

20 CHAIR SUNSERI: Joy Rempe.

21 VICE CHAIR REMPE: Here.

22 CHAIR SUNSERI: Pete Riccardella.

23 MEMBER RICCARDELLA: I'm here.

24 CHAIR SUNSERI: And myself. We'll go 25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.

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5 back. Ron Ballinger, have you joined us yet? Okay.

1 He was just on another line with us. I guess he'll 2

join shortly. But we do have a quorum. So we will 3

proceed on.

4 The ACRS was established by the Atomic 5

Energy Act and is governed by the Federal Advisory 6

Committee Act. The ACRS section of the U.S. NRC 7

public website provides information about the history 8

of the ACRS and provides documents such as our 9

charter, bylaws, Federal Register notices for 10 meetings, letter reports, and transcripts of all full 11 and subcommittee meetings, including slides presented 12 at the meetings.

13 The Committee provides its advice on 14 safety matters to the Commission through its publicly 15 available letter reports.

16 The Federal Register notice announcing 17 this meeting was published on November 20, 2020 and 18 provides an agenda and instructions for interested 19 parties to provide written documents or request 20 opportunities to address the Committee.

21 The Designated Federal Officer for this 22 meeting is Ms. Zena Abdullahi.

23 During today's meeting, the Committee will 24 consider the following, a BWRX-300 topical report on 25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.

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6 reactivity control, and we will proceed into report 1

preparation if time permits.

2 A phone bridge line has been opened to 3

allow members of the public to listen in on the 4

presentation and Committee discussions. We have 5

received no written comments or requests to make oral 6

statements from members of the public regarding 7

today's session.

8 There will be an opportunity for public 9

comment. And we have set aside time in the agenda for 10 comments from members of the public attending or 11 listening to our meetings. Written comments may be 12 forwarded to Ms. Zena Abdullahi, the Designated 13 Federal Officer.

14 A transcript of the open portion of the 15 meeting is being kept. And it is requested that 16 speakers identify themselves and speak with sufficient 17 clarity and volume so that they may readily be heard.

18 Additionally, participants should mute themselves when 19 not speaking. And that's all.

20 So, as far as opening remarks, I really 21 don't have anything else to add. Our agenda is fairly 22 abbreviated for this session. Over the course of the 23 entire meeting, we will be looking at two letter 24 reports in preparation for our Commission briefing, 25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.

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7 along with a planning and procedure session.

1 So that's all I have for my opening 2

remarks. Any members care to make any statements 3

before we get into the agenda? All right. I'm not 4

hearing anything.

5 So our first topic is BWRX-300 topical 6

report. This session is characterized as open and 7

closed. And Dr. March-Leuba is our lead member on 8

this. And so I will turn it over to Jose at this 9

point.

10 MEMBER MARCH-LEUBA: Thanks, Mr. Chairman.

11 We are going to be listening about the reactivity 12 control design requirements in the topical report for 13 the BWRX-300 from GEH.

14 And before we start, I'd like to remind 15 the members that GEH has chosen to protect our 16 intellectual property. And there are many proprietary 17 issues on this topical report.

18 So, if the questions -- we have a closed 19 phone line that we can jump to if there are questions 20 that get into the proprietary nature. So, if I feel 21 that we are going that direction, I will use the magic 22 words of let's table this for the proprietary session, 23 the closed session, and please don't -- at that 24 moment, let's move to the closed session.

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8 That said, I want to thank both the staff 1

and GEH for making the extra work to make all the 2

presentations open so the public can learn about this 3

novel design.

4 And we, the Commission, or not the 5

Commission, the Committee heard about all the 6

proprietary and detailed information in the 7

subcommittee meeting just last month.

8 So, with that said, I believe the staff is 9

going to make the introductory remarks. So, Mike, are 10 you ready?

11 MR. DUDEK: I am. Thank you, Lead Person 12 March-Leuba and Chairman Sunseri and the rest of the 13 full Committee. Thank you for your time today.

14 On behalf of the staff, I'm just going to 15 give brief opening remarks on this third topical 16 report from GEH on reactivity control that requested 17 us to review their design requirements, analytical 18 methodology, acceptance criteria, and regulatory basis 19 associated with these reactivity control functions for 20 their small modular reactor design. As you stated, a 21 lot of this is proprietary and information that we 22 should protect.

23 This meeting comes off the heels of a very 24 successful subcommittee meeting. And I think that we 25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.

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9 are prepared to discuss anything that you have or 1

answer any questions that you have.

2 So, without any further ado, I turn it 3

back over to you. And thank you guys, thank you, 4

Committee, for your time today.

5 MEMBER MARCH-LEUBA: Thanks, Mike. So 6

it's time for GEH to start their presentation.

7 MR. WADKINS: Thank you. This is George 8

Wadkins. I am the Vice President, New Power Plants 9

and Products Licensing for GE-Hitachi.

10 Today we will be presenting an overview of 11 the BWRX-300 small modular reactor design features for 12 reactivity control, including a brief description of 13 the content for licensing topical report NEDC-33912P, 14 BWRX-300 Reactivity Control.

15 As noted in our previous discussions with 16 the ACRS members, the BWRX-300 built upon our 17 extensive experience in boiling water reactor 18 technology, including our most recent experiences in 19 development and certification of the Economic 20 Simplified Boiling Water Reactor or ESBWR.

21 The BWRX-300 is the tenth generation of GE 22 boiling water reactors. And the BWRX-300 design 23 leverages the use of proven technology to the greatest 24 extent possible while incorporating advances in design 25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.

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10 requirements and features to further enhance nuclear 1

safety and to provide for the protection of the public 2

in the unlikely event of an accident. Many of these 3

advances will be discussed today.

4 I first want to thank the NRC staff for 5

their in-depth review of this licensing topical 6

report. It is obvious to GE-Hitachi that the safety 7

review completed by the NRC staff was thorough and 8

focused on ensuring that the content of the licensing 9

topical report was complete, understandable, accurate, 10 and met the applicable regulatory requirements and 11 guidance.

12 As previously requested by the ACRS, we 13 are providing for an extensive open discussion of the 14 content of this licensing topical report. During our 15 presentation, we will pause at the end of each slide 16 to allow for questions from the ACRS members. But 17 please feel free to raise questions at any time.

18 If the discussions involve proprietary 19 information, then we will request tabling the question 20 until the latter closed session.

21 So, proceeding on to slide 2, the purpose 22 of today's presentation includes an overview of the 23 BWRX-300 design features involved in the mitigation of 24 licensing basis reactivity events.

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11 This includes how the BWRX-300 design 1

complies with the applicable regulatory requirements 2

and guidance and how the BWRX-300 design provides for 3

defense-in-depth shutdown capability and reactivity 4

control.

5 The licensing topical report addresses 6

design requirements, acceptance

criteria, and 7

regulatory basis for the BWRX-300 reactor protection 8

system, or RPS for short, and other design features 9

for reactivity control and mitigation of anticipated 10 transients without scram, or ATWS for short.

11 I will now turn over the presentation to 12 David Hinds, principal design engineer for the BWRX-13 300, to discuss defense-in-depth design features for 14 BWRX-300.

15 MR. HINDS: Hello. This is David Hinds.

16 I will first check to ensure you can hear me.

17 MEMBER MARCH-LEUBA: We can hear you.

18 MR. HINDS: Okay. Thank you. All right.

19 So this is a very brief summary of our licensing 20 topical report. I'm trying to touch on technical and 21 the associated licensing input information.

22 And again, if there's detailed questions, 23 we'd be glad to take them. Some of them we may take 24 for the next session.

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12 So, in BWRX-300, we apply a very detailed 1

defense-in-depth approach to the design across the 2

board. And we base that upon the fundamentals of the 3

IAEA approach for defense-in-depth. We think it's 4

quite rigorous and easy for our engineering team to 5

follow and align to.

6 So we have applied that approach, which 7

uses a defense line approach such that it's very clear 8

as to where the layers of defense-in-depth are.

9 And for this discussion today and this 10 licensing topical report, we are focused on the 11 defense-in-depth approach associated with the 12 fundamental safety function of reactivity control.

13 Of course, we have defense-in-depth for 14 the other fundamental safety functions. But, again, 15 this is focused only on reactivity control today, 16 which is to ensure defense-in-depth for shutdown 17 capability and reactivity control. If you could, move 18 to the next slide, please.

19 So, in keeping with what I just stated 20 about our defense-in-depth approach, I'll walk briefly 21 through our defense lines.

22 We begin with defense line 1. And defense 23 line 1 is the fundamental design approach where we do, 24 we apply a high level of quality and reliability and 25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.

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13 conservatism into the design.

1 And some of those design approaches that 2

we use for defense line 1 help to reduce challenges to 3

the plant from a trip perspective, reduces the trips 4

per year, reduces the numbers of AOOs. We use a very 5

rigorous operating experience review approach.

6 And as George stated, since this is the 7

tenth generation of our boiling water reactors, we 8

have a long lineage of operating experience to draw 9

from to build upon and continuous improvement. Next 10 slide, please.

11 Just to highlight a few of the associated 12 design features in the plant associated with 13 reactivity control, we'll start right at the basics of 14 control rods.

15 So our control rods -- and, of course, 16 this is not to scale. Our control rods that we're 17 using have a long period of operating experience.

18 We're using control rods that are already receiving 19 operating experience in the current fleet of boiling 20 water reactors.

21 And this is just showing a visual for 22 anyone that's not used to looking at the figures, and 23 on the right, just shows a visual of how the control 24 rod fits in a control cell or fuel cell with four fuel 25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.

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14 bundles surrounding the control rod blade.

1 So it is a proven design, a high level of 2

reliability. And we have even, in addition to the 3

high reliability that we're currently achieving with 4

our control rods, we have done some additional things 5

(audio interference) for the blades, the control rod 6

blades.

7 We've applied a, what we call an in-8 lattice core such that we have a slightly larger water 9

gap there for the control rod blades to travel between 10 fuel assemblies, helping to minimize any potential for 11 binding or prevention of movement of the rods upon 12 demand. So we've slightly increased the pitch from 13 fuel bundle to fuel bundle, gives plenty of margin for 14 control rod movement.

15 We're also using advancements in the fuel 16 channels that helps to minimize any chance of 17 deformation of fuel channels. We are collecting 18 operating experience on those channels today. We have 19 no evidence of shadow corrosion on those NSF type 20 channels that we're using.

21 And these, this type of design, it also 22 helps ensure we have a very high degree of shutdown 23 margin as well. Can you move to the next slide, 24 please?

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15 So, just touching on some of the 1

associated regulations, and then I'll continue through 2

the defense lines as well. So 50.62, 10 CFR 50.62 was 3

one of the regulations that was addressed in the 4

licensing topical report.

5 In that regulation, one of the explicit 6

requirements is for alternate rod insertion system.

7 And we do have the ARI system, which we have 8

experience with on our current operating fleet.

9 And in the slide here, I have the brief 10 summary of the hydraulic scram function or hydraulic 11 ability to insert the control rods.

12 So our control rods are driven on the 13 BWRX-300 by fine motion control rod drives. Our older 14 plants have hydraulic only or locking piston control 15 rod drives.

16 The BWRX-300, just like the ABWR and 17 ESBWR, apply a newer design, which also has operating 18 experience of fine motion control rod drives. They 19 have motors to, electric motors to provide the normal 20 control rod movement in both directions, insert and 21 withdraw, for very small and fine motion. That's for 22 normal power control and also serves as a backup to 23 hydraulics for quick shutdown.

24 The hydraulics are there on this design, 25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.

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16 unlike the current operating fleet of only hydraulic, 1

the hydraulics on this design, as water hydraulics, 2

are only there for the purpose of fast shutdown, i.e.,

3 scram.

4 So we use pressurized water in 5

accumulators, stored energy. Many of you, if not all 6

of you, are probably quite familiar with the operating 7

fleet of the HCUs.

8 So we have redundancy by providing 9

hydraulic control units. Two control rods are aligned 10 to each HCU. We have, the HCUs are actuated by a 11 reactor protection system. And in the BWRX-300, we 12 also have a diverse means.

13 Then, we additionally have a ARI function 14 that will depressurize the scram air header if 15 necessary to provide further backup for insertion or 16 reactor scram if needed.

17 So this is somewhat of a busy slide. But 18 it's somewhat busy because we have many ways to get to 19 the control rods. And so I'll run back through again, 20 because I maybe jumped around a little.

21 Control rods normally inserted and 22 withdrawn by electric motors through the fine motion 23 control rod drives. They're inserted with hydraulics 24 for fast shutdown in a scram. The hydraulics are 25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.

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17 actuated by our reactor protection system. And 1

there's also a diverse means to actuate them.

2 In addition to those two means to actuate 3

the hydraulic control units, if there's a common cause 4

failure of hydraulic control unit actuation, there's 5

a diverse ARI, depressurization to cause the scram as 6

well.

7 So that's basically three ways to get the 8

hydraulics and the electric motors, also in addition 9

to their normal power control, can provide a backup to 10 insertion during the case of a failed scram. So 11 that's a little, brief summary of a little complicated 12 discussion.

13 But in addition, at the very bottom of 14 this slide, for those who are quite familiar with the 15 operating fleet hydraulics, one of the possible, not 16 likely but possible, failure modes was hydraulic lock 17 of the scram discharge volume.

18 I'll note that on this design we've 19 additionally incorporated a way to remove the scram 20 discharge volume. And it's just a one-way insertion 21 of hydraulics. Okay. If we could, move to the next 22 slide, please.

23 MEMBER MARCH-LEUBA: Jose. By that, you 24 mean instead of discharging into, a dedicated volume 25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.

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18 will discharge into the vessel, correct?

1 MR. HINDS: That is correct. Okay. I'll 2

keep on moving. And I'll be glad to take questions 3

any time.

4 So defense line 2 is -- so defense line 1 5

is more programmatic and fundamental features and 6

design decisions, such as the in-lattice.

7 Once we get into defense line 2, 3, and 4, 8

we have systems and features that may actuate or 9

control to improve safety of the plant or to respond 10 to an event.

11 And defense line 2,

that includes 12 functions that normally control the plant, such as 13 pressure control, water level control, things, rod 14 control, normal control features of the plant.

15 And we have a high level of quality 16 applied to defense line 2 than just plain non-safety 17 equipment, but not to the pedigree of the full safety-18 related or safety class 1 equipment. However, it does 19 have enhanced quality and reliability features applied 20 to the design and the procurement.

21 The defense line 2 is, includes functions 22 to control or stop postulated initiating events. You 23 know, I mentioned pressure control and level control, 24 key features in control of the plant.

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19 So the quality that we place and the 1

redundancy that we place into these systems minimizes 2

postulated initiating events that could challenge the 3

safety class 1 or safety-related systems that will be 4

in defense line 3 as I get to that.

5 Defense line 2 is independent from defense 6

line 3 all the way through, provides a high 7

reliability and, again, reduces the challenges to the 8

plant from a trip perspective. If you could, go to 9

the next slide, please.

10 Here's another design feature just 11 highlighting, of course, the reactor pressure vessel.

12 Just to, there are many things to talk about on the 13 reactor pressure vessel, but I'll only highlight a 14 couple of them.

15 One is, this is a natural circulating 16 boiling water reactor similar to the ESBWR but smaller 17 in size. So we took ESBWR concept, and we scaled it 18 to a nominal 300-megawatt electric power plant.

19 However, many of the features that come 20 with natural circulation are quite helpful in 21 mitigating events.

22 So the part I'll highlight here is large 23 steam volume. It's a higher volume to power ratio as 24 compared to, for example, the ESBWR. So the high 25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.

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20 volume to power ratio minimizes any pressurization 1

transients.

2 However, in part of our defense line 1 3

design decisions, we added conservatism in. Even 4

though we have that larger volume to power ratio, we 5

have chosen to raise the design pressure from our 6

historical values such that we have additional margin 7

in the design pressure of the reactor vessel, and we 8

have a higher volume to power ratio. So, therefore, 9

the pressurization transients are not a challenge for 10 this plant.

11 And we've already gone through a previous 12 LTR, as listed here, for the reactor pressure vessel 13 isolation and overpressure protection. However, that 14 overpressure or that volume to power ratio and the 15 minimization of pressurization helps also in 16 reactivity abnormal events such as a slow or failed 17 scram. Okay. If you could, go to the next slide, 18 please.

19 Defense line 3 is the heart of safety.

20 That's our highest safety class right in the middle of 21 our defense-in-depth and posture. So safety class 1 22 or safety-related systems reside in defense line 3.

23 And it includes the functions to mitigate 24 a postulated initiating event, assures the plant is 25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.

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21 placed in a safe condition, assigned the highest 1

safety class. And we ensure that we have independence 2

from defense line 2, and for that matter, independence 3

from defense line 4 as well.

4 MEMBER MARCH-LEUBA:

Dave, this 5

independence from DL 2, is there going to, do you --

6 obviously, you have the final design. But you won't 7

have any detailed communications between the control 8

system and the protection system, DL 2 and DL 3?

9 MR. HINDS: They are separate digital 10 control systems. The only potential would be for 11 protected communication, for

example, one-way 12 information sharing, but not -- there will be 13 protected communications, if any. They are completely 14 separate systems.

15 MEMBER MARCH-LEUBA: Most likely, I would 16 imagine, the communication will go from DL 3, if a 17 scram happens, and you pass it to the control system.

18 MR. HINDS: Yes.

19 MEMBER MARCH-LEUBA: And those should be 20 unidirectional.

21 MR. HINDS: Yes.

22 MEMBER MARCH-LEUBA: And when we review 23 the details, we are going to be very interested on the 24 architecture and make sure that those unidirectional 25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.

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22 communications are really unidirectional.

1 MR. HINDS: I understand.

2 MEMBER MARCH-LEUBA: Okay.

3 MEMBER BROWN: By that he means not 4

software configured. This is Charlie.

5 MR. HINDS: Okay. I understand.

6 MEMBER BROWN: Hardware, data diode type, 7

one way, not configured by software.

8 MR. HINDS: Okay. I understand. And 9

we'll have, for any license submittal, we would go 10 into, of course, great detail on the I&C architecture 11 and address those features. But I understand your 12 comments. Thank you.

13 MEMBER BROWN: And I presume that will be 14 covered in the, when we finally get to a reactor 15 protection system topical report or whatever you're 16 going to issue for that, will provide that as well as 17 the information of how you intend to achieve, not the 18 detailed parts, obviously, but the architecture 19 approach --

20 MR. HINDS: Yes, for future licensing 21 submittals, yes. Now, there's further decisions to be 22 made as to whether they would be under a licensing 23 topical report or under an actual application. But, 24 yes, I agree with your statement.

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23 MEMBER BROWN: Okay. That's fine. I just 1

wondered where it's going to be, because, I mean, when 2

I went through the other, these other documents, so 3

far there's -- you talk about the RPS as an RPS and 4

you say what it's going to do, but there's no other 5

details. That's all.

6 MR. HINDS: That is correct. Your review 7

is correct. So I agree with your statements.

8 MEMBER BROWN: Okay. Thank you.

9 MR. HINDS: Okay. If you could, move to 10 the next slide, please.

11 Okay. One of the key systems within the 12 highest of safety classes, in addition to the reactor 13 protection system, is the isolation condenser system.

14 So I mentioned that the RPV itself has 15 certain pressure mitigating features by its volume to 16 power ratio. However, the pressure control is 17 primarily at least in the safety class 1. In an event 18 where we have an isolation, we use an isolation 19 condenser system.

20 We inherited the design from ESBWR as far 21 as the condensers themselves. We are applying three 22 trains of the same size of condensers that we applied 23 on ESBWR.

24 So, by doing that, with this smaller power 25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.

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24 plant, we have a very large margin and significant 1

capacity for minimizing any pressurization transients 2

and controlling any challenge to pressurization by use 3

of the isolation condenser system.

4 It primarily operates in a passive mode.

5 This is a very simplified figure that doesn't show the 6

valves. There are valves in here.

7 But all it takes to actuate the system is 8

the opening of one valve in the return line, the 9

condensate return line to the vessel. And there are 10 parallel, diverse means in that condensate return line 11 to actuate. And in the worst case, if we were to lose 12 all power and signal, it fails in the in-service 13 condition.

14 And again, there's redundancy here as well 15 with a very simple actuating system. Once placed in 16 service, it stays in service and requires no support 17 features once placed in service.

18 Again, there's three trains. We have them 19 as a staggered operating points for the automatic 20 initiations on pressure such that they don't all come 21 into service at the same time. But in a severe event 22 where, such as a complete failure to scram, we would 23 expect to hit all three and use them to mitigate the 24 event.

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25 Again, failsafe, simple system. And 1

again, we drew upon the program from ESBWR, which 2

included a full-scale test of these isolation 3

condensers. And we also covered this design feature 4

in our previous LTR for overpressure protection as 5

well.

6 MEMBER MARCH-LEUBA: Dave, this is Jose 7

again. Typically when we do these things, we have 8

competing requirements. From the thermal-hydraulic 9

point of view, it's super exciting to have extra 10 capacity because you can cool down better. You can 11 cool down more and you can cool down with failures.

12 From the criticality safety point of view, 13 you can bring the core to cold. And I'm going to ask 14 you to remind us that no matter how cold the core 15 gets, even with two blades stuck out, you are not 16 going to return to power. That's your requirement, is 17 that correct?

18 MR. HINDS: That's correct. We, as I've 19 mentioned before when I was talking about the 20 hydraulic control units, we have one hydraulic control 21 unit aligned to two control rod drives. And we assume 22 a failure of one of those hydraulic control units and 23 still have adequate shutdown margin.

24 We have ample shutdown margin. In fact, 25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.

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26 I think we'll be fine with more than that. However, 1

that's what our analyzed state is, is two stuck-out 2

control rods with ample shutdown margin.

3 MEMBER MARCH-LEUBA: And you plan to do 4

this with all three ICS running at full blast and 5

making the core as cold as it can possibly get?

6 MR. HINDS: Yes, within reason, yes. So 7

yes, agree with your statement.

8 MEMBER MARCH-LEUBA: Thank you.

9 MR. HINDS: So we do have, you know, 10 temperature extremes on our analysis. I think that's 11 permanently addressing your point. And I'll note that 12 we do include some design enhancements from the ESBWR.

13 To get into details on those, if you're interested in 14 getting that level of detail, we'd prefer to discuss 15 that in the closed session.

16 But it does help with, I'll just simply 17 state that those design enhancements improve the 18 pressure control while helping with the reactivity 19 control. So this system helps with pressure control 20 while at the same time assisting with reactivity 21 control. Okay, if we could go to the next slide, 22 please.

23 MEMBER KIRCHNER: David, this is Walt 24 Kirchner. So going back to your statement, you 25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.

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27 mentioned there's defense line 3 is the highest 1

quality class, I'm -- or safety class. I just assume 2

that the reaction coolant pressure boundary as 3

illustrated in this diagram then would also be of the 4

highest quality.

5 MR. HINDS: That's correct.

6 MEMBER KIRCHNER: Safety-related if you're 7

using 10 CFR 50 or 52 definitions.

8 MR. HINDS: Yes, that is correct. And 9

we've applied --

10 MEMBER KIRCHNER: Thank you.

11 MR. HINDS: We've applied the IAEA 12 approach, we've been using terminology of safety class 13 I, II, and III. But I agree with your statement. And 14 so this system is a safety class I or safety-related 15 system highest safety class, that's correct.

16 MEMBER BLEY: David, this is Dennis Bley.

17 I want to go back to what Jose was talking about. And 18 I don't think it's for this current report, but later 19 when we get to this design cert review, you mentioned 20 that the intent is to have maximum ICS occur.

21 You know, in the past, at least in some 22 places, people have worried that that was too much and 23 developed thoughts about how to cut it back, which can 24 lead to significant problems. We'll be interested in 25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.

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28 discussing that when we get into details, that system.

1 MR. HINDS: Okay, thank you. And the part 2

when I mentioned, alluded to some design enhancements, 3

and I'll be glad to discuss a little further in a 4

closed session, will help with your question as well.

5 So I understand your question. And that staggered set 6

point that I mentioned earlier, that also helps with 7

your question as well. But I understand it.

8 So we have evaluated inadvertent IC 9

actuation as part of our standard suite of analysis, 10 and so I understand. Okay.

11 MR. SCHULTZ: Dave, Steve Schultz. In the 12 system that you've described, the return valves fail 13 open, and also they're -- the system is failsafe.

14 With regard to operator action, any operator actions 15 that are proposed or could take place that would close 16 those valves?

17 MR. HINDS: No, the operator is not --

18 okay so I think you asked that, I'll address your 19 question in two ways, and hopefully one way will 20 answer you. It is one is that the system completely 21 actuates without operator action. I think the other 22 side of your question is could the operator cause a 23 problem by disabling the safety function.

24 We have that as a design requirement to 25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.

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29 ensure that the proper human factors, of course there 1

will be operators and the operators will be expected 2

to be aware of this situation and monitor. Part of 3

our human factors design will take into account the 4

human reliability analysis and potential that an 5

operator could disable a safety function.

6 And our intent that we're still working 7

through is that that would not occur. It is an 8

automated system and so I do not think that's 9

difficult to achieve.

10 MR. SCHULTZ: Good, thank you.

11 MR. HINDS: Okay, thank you. If we could 12 move to the next slide, please. Okay, so now we're up 13 to the backup defense behind the safety-related 14 systems, which should hopefully never be called upon.

15 So, defense line 4-alpha, and we've take the IAEA 16 defense lines 4 and split to 4-alpha and -bravo.

17 Won't talk much about 4-bravo, it's more like the flex 18 or deep defense-in-depth.

19 But in the defense line 4-alpha, we have 20 functions to mitigate the postulated initiating event, 21 similar to the goals of defense line 3, but it's in a 22 backup way. And this is there to mitigate times when 23 defense line 3 or the safety-related systems are 24 called upon and experience a common cause failure.

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30 They're ensured -- they also ensure that the plant is 1

placed in a safe state.

2 If you go to the next slide, please.

3 MEMBER MARCH-LEUBA: Dave, go back to this 4

slide.

5 MR. HINDS: Sure.

6 MEMBER MARCH-LEUBA: And have you ever 7

seen a non-proprietary setting, an example so we can 8

think what you're --

9 MR. HINDS: Yes.

10 MEMBER MARCH-LEUBA: We can focus on what 11 you're talking about?

12 MR. HINDS: Certainly, ARI. So I touched 13 on, because I talked about many features of the 14 control rod movement in an earlier slide, I hit may 15 defense lines. So I hope I didn't confuse things 16 there, I was worried about that slide.

17 So with the control rod insertion, I hit 18 many defense lines there. If you remember, there's 19 many ways to insert the control rods. So an example 20 of the defense line 4-alpha method to insert the 21 control rods is the ARI. And then there's some others 22 where we would get a little further into proprietary.

23 But, and I'll be glad to discuss further. But that's 24 an example, ARI, alternate rod insertion.

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31 MEMBER MARCH-LEUBA: Okay, I'll make a 1

note to ask you in the closed session, because I'm 2

interested. Is this defense-in-depth actions going to 3

be performed by a non-safety-grade computer?

4 MR. HINDS: They are a lower safety class 5

than what in the US we'd call safety-related.

6 However, we are applying the IAEA approach, so it's 7

not just taken all the way back to what you would 8

think of non-safety as a graded approach to quality.

9 So we've applied a safety class II, which a not all 10 the way to the level of safety-related, but not all 11 the way down to the level of non-safety-related and 12 augmented quality.

13 MEMBER MARCH-LEUBA: So in I&C lingo, it 14 will be redundant but not diverse?

15 MR. HINDS: This platform in defense line 16 4 is diverse from defense line 3.

17 MEMBER MARCH-LEUBA: All right, but within 18 itself, it will be more than one channel, hopefully 19 three. But they will all be the same type of 20 computer.

21 MR. HINDS: Correct, this is appropriate 22 level of redundancy, but it could be all the same, it 23 could be all the same technology within the 24 redundancy.

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32 MEMBER MARCH-LEUBA: Okay, thank you.

1 We'll look at those details with the next --

2 MR. HINDS: Okay.

3 MEMBER MARCH-LEUBA: Yes, I'm sure.

4 MR. HINDS: Okay, thank you. All right, 5

next slide please. Okay, just a little bit into --

6 further into the ATWS rule, 50.62. These are -- this 7

is really a restatement of ATWS rule, which I'm sure 8

you're well aware of. So, but only pulling out the 9

portions of the ATWS rule 50.62 which apply to boiling 10 water reactors specifically, ARI, SLC, and automatic 11 recirc pump trip. Can you go to the next slide 12 please.

13 Okay, as far as going through those 14 features. So automatic recirc pump trip. As I stated 15 earlier, this is a natural circulating power plant, so 16 therefore the automatic recirc pump trip is deemed to 17 be not technical relevant in that we do not have 18 recirc pumps to trip, so therefore we do not include 19 a recirc pump trip feature.

20 However, the purpose of the recirc pump 21 trip is to minimize a reactivity in the case of a 22 failure to scram, and we do have other features to 23 minimize reactivity in a similar fashion.

24 So basically we can control water level 25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.

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33 within the reactor, and the enhancements that I 1

mentioned for the isolation condenser system that I 2

can discuss further in the closed session help in this 3

respect as well. We, the feedwater system is 4

controlled as well to minimize reactivity effects.

5 Okay, if we could go to the next slide, please.

6 So the SRP, we just stayed a little bit 7

out of the SRP, and I'm sure the NRC will cover this 8

further, so I'll go over it very quickly, is the SRP 9

related to 15.8, related to the ATWS rule. And there 10 is a statement in there, in the SRP, that talking 11 about evolutionary plants, which we think the BWRX-300 12 is an evolutionary plant.

13 And it says that you could have a diverse 14 scram system and satisfying design and quality 15 assurance criteria. And/or you could demonstrate the 16 consequences of the ATWS event or within acceptable 17 values.

18 In keeping with our defense-in-depth 19 approach, we've addressed both of these so we do have 20 a diverse means of shutdown, the details of which I've 21 kind of alluded to at a very high level, but I can 22 talk a little further in the closed session. But we 23 do have a diverse means to shut down. I talked about 24 it a little bit in a very high level in the prior 25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.

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34 slides. We do have ARI and we do have electric motors 1

to move the control rods that are in addition to the 2

normal hydraulic scram.

3 I've listed there, a little bit to the 4

question a minute ago, where ARI and electric motor 5

run-in are included in defense line 4-alpha. And 6

there's multiple defense lines that are ensuring the 7

hydraulic insertion occurs as well in defense line 2, 8

3, and 4-alpha.

9 MEMBER BROWN: Does the next -- this is 10 Charlie Brown.

11 MR. HINDS: Yes.

12 MEMBER BROWN: Does the fine motor control 13 drive, is that able to insert rods at a fast enough 14 speed to handle the reactivity transience? Is that --

15 it's intended to do that as well?

16 MR. HINDS: Yes. So it's -- great 17 question. It's, during normal operation, we want the 18 fine movement to minimize the reactivity effects at 19 high power, for example. However, the speed is 20 calibrated such that we have an insertion capability 21 that is fast enough to handle the complete failure of 22 all of the other means to get the control rods in.

23 So if all of those other means that I 24 discussed on the hydraulic actuation, as well as the 25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.

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35 ARI, all of them fail, the control rod insertion by 1

motors is fast enough. And that's coupling that with 2

the pressure control features of the isolation 3

condenser system that I just talked about earlier. So 4

short answer is yes, it is fast enough.

5 MEMBER BROWN: Is, does that -- based on 6

your comments, does that mean it has more than one 7

speed? In other words, for insertion it can go faster 8

than you would -- than you would necessarily for your 9

fine motion control during normal operations?

10 MR. HINDS: We're actually still working 11 on whether we're going to adjust the speed any during 12 normal operation, but we do have this setting for the 13 rapid insertion, as we discussed here. We're planning 14 to use servomotors, which have a capability to move at 15 variable speeds. So it's likely that we will have a 16 slower speed during high power operation, but we're 17 still working through making that decision. But it's 18 an excellent question.

19 MEMBER BROWN: Okay, thank you.

20 MR. HINDS: Okay, if we can move to the 21 next slide please, I'll try to wrap up.

22 MEMBER MARCH-LEUBA: While we're on the 23 open session, let me just say that we, ACRS, are going 24 to be terribly interested. I know you, the design 25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.

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36 team, has spent a lot of time thinking about ATWS and 1

during the review, both the staff and ACRS are going 2

to be very interested in this topic when you have the 3

final design and the final calculations to ensure that 4

nothing can go wrong. Just putting it on the record, 5

and we'll talk more about this in the closed session.

6 MR. HINDS: Okay, all right, understand.

7 So just a brief summary here, don't -- hopefully don't 8

need to go into much detail. But here's the listing 9

of regulatory acceptance criteria, all pulled from 10 regulations. So I don't think any, should be any 11 surprises here. So we have pressure requirements, 12 fuel integrity, containment integrity, rad release, 13 and ensuring that shutdown and long-term cooling are 14 all evaluated and analyzed.

15 Okay, if no questions there, I'll keep on 16 moving and trying to keep the time moving. Okay, and 17 so I think this is the last slide in this --

18 MEMBER BROWN: Sir, can I ask one other 19 question? I kind of forgot.

20 MR. HINDS: Sure.

21 MEMBER BROWN: You mentioned this as back 22 on the speed of the time motion motor controls.

23 MR. HINDS: Yes.

24 MEMBER BROWN: You mentioned that that was 25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.

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37 going to be servos.

1 MR. HINDS: That's our intent, yes.

2 MEMBER BROWN: Okay. And --

3 MR. HINDS: We do have some options there 4

where we have some motors that we've used previously 5

that are stepper motors and we have some motors we've 6

used previously that are induction. But our current 7

preference is servos. We've not procured them yet, so 8

there is a chance that that would change, but our 9

current intent is servomotors.

10 MEMBER BROWN: The reason I ask is that 11 servomotors don't always have the same torque 12 characteristics that an induction motor or even a step 13 motor. I'm familiar with both the step motors, I had 14 rod control systems that were step motors in my old 15 plants in the Navy, in one of the design plants. And 16 the motor control were basically reluctance motors, 17 which you could control and make sure they had enough 18 torque.

19 But servomotors don't always have a lot of 20 torque since they're pretty fine control type devices.

21 That was my only question is are those really 22 satisfactory for a higher speed type insertion where 23 you might need to generate some additional torque.

24 That's the only thought process I had.

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38 MR. HINDS: Yes, we have applied torque 1

specifications to our motor supplier and not had any 2

problem to date with aligning to get a supplier for 3

that. But I agree with your focus on that topic. We 4

do not think we'll have a problem meeting it.

5 MEMBER BROWN: Okay.

6 MR. HINDS: But again, we do have further 7

work to be done and through the procurement cycle, but 8

we do have a supplier that we think can meet our 9

requirements there on torque.

10 MEMBER BROWN: Okay, thank you.

11 MR. HINDS: Okay.

12 MEMBER MARCH-LEUBA: The rules of the game 13

-- this is Jose -- the rules of the game is, we don't 14 design the reactor for you, but in my opinion, I would 15 go for the highest torque, the biggest force you can 16 have on that FMC, I mean, the fine motion control rod 17 drive, the electric motors. So that even if there is 18 some binding, you can push the rod in. And I can 19 control the velocity by stepping it slowly with a step 20 motor.

21 Just think about it. I mean, the safest 22 thing is to have the high -- the biggest motor you can 23 find that will push the rod in no matter what. And --

24 okay, that's it. I'm not helping you design your 25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.

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39 reactor, but just giving you some hints.

1 MR. HINDS: Okay. Okay, thank you for the 2

comment, I understand the nature of it. Thank you.

3 So the final slide here in this segment is 4

we did highlight another one of the regulations, the 5

GDC 27, and we just highlight it here because we go 6

through in the LTR and evaluate all the appropriate 7

GDCs and regulatory documents associated with 8

reactivity control. And I'll highlight this one in 9

addition to the ATWS rule, just because we had an 10 alternate means of compliance or actually an 11 exception.

12 And it's primarily just the wording of the 13 GDC and that the GDC is, so you can see above, the 14 reactivity control system shall be designed to have a 15 combined capability in conjunction with poise and 16 addition by ECCS of reliability, the reliability 17 controlling reactivity changes to assure under 18 postulated access. Anyway, you can read it.

19 We changed the words but meet the intent, 20 just because the words didn't explicitly align with 21 our design since we are, as stated in our prior 22 submitted LTR and reviewed LTR on the RPV isolation 23 and overpressure protection. We do not rely upon ECCS 24 injection systems and associated borated coolant.

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40 And therefore the wording of this did not 1

explicitly apply, so we've reworded it but still meet 2

the intent such that core coolability is maintained 3

for a locus. Because we have sufficient water 4

inventory, and we're assuring that through the RPV 5

isolation. So we preserve the coolant and we do not 6

have a borated solution and there's no concern with 7

ECCS injection diluting a borated system and causing 8

a reactivity excursion.

9 So this -- I think, we feel like was 10 written for different type designs, and so we've 11 applied a PDC to substitute for the GDC, and that's an 12 exception stated in the LTR.

13 MEMBER BROWN: Presume when you do your 14 submittals in whatever form they are, they will 15 somehow address the fact whether the plant will be 16 able to be shut down under all temperature conditions, 17 the sub-critical as opposed to perking along at low 18 power for weeks?

19 MR. HINDS: Yes, and as I stated before, 20 as we do our shutdown margin calculations with the two 21 highest worth control rods associated with an HCU 22 fully withdrawn and we have ample shutdown margin.

23 And we also have a temperature range which we apply to 24 that, and so I think we will not have a problem 25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.

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41 meeting the point that you're alluding to.

1 MEMBER BROWN: Okay, thank you.

2 MR. HINDS: Okay. That's it for the slide 3

presentation, and I think I've exceeded my time, I'm 4

sorry.

5 MEMBER MARCH-LEUBA: Well, you did good.

6 Just as a reminder to the members, we are going to 7

have an open presentation by the staff, and then we 8

are going to go to the closed session to see some 9

details of calculations by GEH. And we have plenty of 10 time.

11 Our plan is to read the letter, the ACRS 12 letter in the open session, so we will have the staff 13 present open session here. We will all, that are 14 allowed to, move to the closed session to see those 15 calculations, and then we'll come back to the open 16 session to read the letter.

17 And on that line, GE, Zena is going to 18 send you the final copy of the letter, because we've 19 made some modifications based on members' inputs. And 20 if you could give it a quick read to make sure the 21 modifications did not put any proprietary information 22 on it, we would appreciate it. And we have to do it 23 real fast.

24 So staff, can you start your presentation 25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.

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42 please.

1 MR. NOLAN: Okay, thank you. This is Ryan 2

Nolan. I'm in the Nuclear Methods and Systems and New 3

Reactors Branch in NRR, and I'll be presenting the 4

staff's presentation for our review of the BWRX-300 5

reactivity control topical report. And I will be 6

assisted by Marieliz Johnson, who is helping me with 7

the slides today. Marieliz, you can go to the next 8

slide.

9 So here's an outline of the presentation 10 today. We'll quickly go through the review team, a 11 little bit of background on the BWRX-300. The bulk of 12 the presentation will focus on the staff's review of 13 specific regulatory requirements, and we'll wrap up 14 with the conclusion.

15 These slides are very similar to what you 16 saw in the subcommittee meeting. However, I plan on 17 just touching the highlights and not going into the 18 full detail that we did in the subcommittee meeting.

19 However, if there are questions we can certainly go 20 into more details. Next slide, Marieliz.

21 So this is just to present the review 22 team, many of which are here to support, answer any 23 questions that I cannot. So with that, you can move 24 to the next slide, Marieliz.

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43 So a quick background. BWRX-300, it's a 1

300-megawatt electric SMR. It's natural circulation, 2

uses a passive cooling isolation condenser. The 3

control rods are typical BWR control rods that we're 4

all familiar with.

5 This design does include some defense-in-6 depth and diverse features with respect to reactivity 7

control for ensuring the reactor is properly 8

controlled and shut down. And this topical report 9

goes through specific requirements, design 10 requirements, as well as assesses regulatory 11 requirements specific to reactivity control functions.

12 Next slide, Marieliz.

13 So here's a short list of the specific 14 design features that are included, or and systems that 15 are included in the BWRX-300 design. I'll just 16 briefly step through each one. The control rod system 17 is made up of control rods, we've already talked about 18 them, GE provided a good overview, as well as control 19 rod drives.

20 The drives are split up into the safety-21 related rapid insertion function that's performed 22 hydraulically, as well as a non-safety-related fine 23 motion control function that uses electric motors and 24 is used for normal operation as well as a scram 25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.

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44 follow-up function as a backup means.

1 Also, there's an alternate rod insertion 2

system. This provides a diverse means of a hydraulic 3

scram in the event of an HCU failure. And it uses 4

energized to actuate pilot valves. And so it's an 5

alternate means to vent the control air. Next slide, 6

Marieliz.

7 This is a list of the regulations that we 8

addressed in the safety evaluation. I'm going to go 9

through each. I'll go through the ATWS rule first, 10 and then I will go through each of the GDCs that's 11 underlined. I do not have specific slides on the GDCs 12 which are not underlined. This is mainly due to the 13 means for the requirements or design requirements on 14 certain systems for meeting these requirements are 15 fairly traditional and straightforward.

16 And so just at a high level, the GDCs 17 which are not underlined, the staff found that the 18 approaches described in the topical report were 19 consistent with the associated GDCs, and we found 20 those to be acceptable. So with that, we'll talk 21 about 50.62 on the next slide. Marieliz.

22 So the topical report defines the 23 acceptance criteria for evaluating the effectiveness 24 of the reactivity control systems and functions. It's 25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.

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45 listed here on this slide. These are consistent with 1

the SRP, as well as it's consistent with the 2

acceptance criteria that the operating fleet has used 3

to evaluate the ATWS transients. Next slide, 4

Marieliz.

5 So first, specific requirement for 50.62 6

related to BWRs is C3. This requires all BWRs to have 7

an alternate rod insertion system that's diverse from 8

the reactor trip system.

This is fairly 9

straightforward because the BWRX-300 uses a fairly 10 traditional ARI system. They commit to having one, 11 and so the staff found that that approach is 12 acceptable and consistent with the requirement. Next 13 slide.

14 50.62(c)(4) requires BWRs to have a 15 standby liquid control for injection into the vessel.

16 The topical report specifies that the design will meet 17 the risk goals for 50.62, which is a probability of an 18 ATWS is less than one times ten to the minus five per 19 reactor year. This is achieved through diverse scram 20 actuation logic, diverse rod motor force, as well as 21 a couple other things that is proprietary.

22 The staff found that this risk goal is 23 consistent with the intent of 50.62, and this could be 24 used as -- to support a future exemption if so 25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.

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46 desired. We did write a limitation and condition on 1

this, next slide. We wrote several limitations and 2

conditions in certain areas where the topical report 3

maybe didn't go into a lot of detail as what type of 4

analysis will be performed in the future.

5 And so we just wanted to clarify some of 6

the staff's expectations or what we would expect to 7

demonstrate some of the statements that were included 8

in the topical report. So specific to ATWS, we have 9

a limitation and condition to provide a reliability 10 analysis that takes into account operating experience 11 in order to demonstrate that the probability of an 12 ATWS is less that one times ten to the minus five per 13 reactor year, demonstrating the intent of the rule is 14 satisfied.

15 50.62(c)(5) requires BWRs to automatically 16 trip the recirculation pumps under ATWS conditions.

17 This one as well is fairly straightforward. It's not 18 applicable to the BWRX-300 because it is a natural 19 circulation -- a plant does not have recirc pumps.

20 And so this regulation is not applicable to the BWRX-21 300. However, the design does have compensating 22 measures, which is proprietary, and we did discuss at 23 the subcommittee meeting. Next slide.

24 So now we're going to step through some of 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

47 the general design criteria. The first one is GDC 12, 1

which requires control and protection systems to 2

ensure that oscillations that could exceed the SAFDLs 3

are prevented or they're detected and suppressed.

4 The topical report specifies that the 5

BWRX-300 will meet GDC 12 through several design 6

features, some of which are included here, which is a 7

small core, sort of a newer of form of orifice design, 8

a coupled power to flow response, as well as the 9

design of the RPB chimney. We wrote a limitation 10 condition on this as well. Next slide.

11 And this is really just to ensure that the 12 analysis which demonstrates some of the statements 13 made in the topical report is performed using an 14 approved method. And that's really the intent of this 15 limitation condition, is to make sure that there is an 16 appropriate analysis to demonstrate GDC 12 is met.

17 MEMBER MARCH-LEUBA: Ryan, this is Jose.

18 We talked about some of this in the subcommittee.

19 When we say approved method, do we need to have a 20 topical report that says NRC approves it for use in 21 the BWRX-300? Or an approved method for ESBWR is 22 acceptable? Or does it need to be extended? Can you 23 talk a little bit about approved methods?

24 MR. NOLAN: Yeah, yeah, we did talk about 25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.

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48 it a little internally as well, just briefly. And 1

there needs to be demonstration that the topical 2

report is applicable to the BWRX-300. I think there's 3

some flexibility in how that's done. Traditionally 4

that is done through topical reports.

5 But I think the staff is open and is 6

flexible to how that is documented. So I think at a 7

minimum it needs to be documented somewhere.

8 Traditionally it's the topical report, but it probably 9

doesn't have to be.

10 MEMBER MARCH-LEUBA: Okay, so we'll 11 revisit this in the future, and it's for GEH and the 12 staff to negotiate what will be acceptable. Clearly, 13 I

think we all

agree, even

GEH, that the 14 recommendation needs to be performed. And the 15 question is how we do it with minimal pain. Okay, 16 thank you.

17 MR. NOLAN: Certainly. Next slide. So 18 GDC 26, it requires two independent reactivity control 19 systems based on different design principles. The 20 topical report specifies that the BWRX-300 will meet 21 the GDC by providing control rods, which is used for 22 normal operations including AOOs and addresses 23 malfunctions, as well as holding the reactor 24 subcritical under cold conditions.

25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.

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49 And then the feedwater level control 1

system is used to satisfy bravo above, which, you 2

know, is used to adjust the reactivity control during 3

planned and normal power outages. And this of course 4

is something that we will review obviously in more 5

detail once we get an application. But as described 6

in the topical report, it is consistent, the approach 7

is consistent with GDC 26.

8 So GDC 27, the intent of the GDC is to 9

require reactor designs to achieve and maintain 10 subcriticality, and this is using only safety-related 11 equipment following accidents, as well as addressing, 12 taking into account single failures. And as was 13 discussed by GEH in their presentation, they proposed 14 a PDC.

15 It maintains fundamentally all of the same 16 information that is in the GDC, with a focus of just 17 satisfying the intent of that regulation. And as was 18 discussed already, the BWRX-300 will use the control 19 rods to ensure that the reactor remains subcritical 20 under cold conditions.

21 We do expect to see an analysis in the 22 future which would demonstrate this. That analysis 23 would look at both, you know, instantaneous shutdown 24 margin, as well as, you know, a long-term shutdown 25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.

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50 margin, which would account for, you know, any 1

cooldown from the isolation condensers.

2 MEMBER KIRCHNER: So Ryan, this is Walt 3

Kirchner. Just a process question. So they are 4

proposing a PDC in lieu of the GDC, and then in the 5

actual review of an application, then this would 6

require a formal exemption.

7 MR. NOLAN: That's correct. I think, you 8

know, as we, you know, we've been reviewing some 9

interesting designs recently and some exemptions are 10 maybe more administrative in nature and less 11 technical, and perhaps this would fall into that 12 category.

13 So technically from a legal perspective, 14 yes, it would require an exemption. However, I don't 15 think it raises any substantial technical issues or 16 concerns at this point. It's more just a matter of 17 documenting it.

18 MEMBER KIRCHNER: Yeah, and analysis will 19 demonstrate that they have the rod work necessary to 20 keep it shut down as in subcritical through a range of 21 conditions. And it's been brought up earlier, you 22 know, obviously it's the temperature, it's the 23 cooldown that would be something to look at in the 24 future.

25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.

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51 Okay, I'm just checking how you're doing 1

this now. And then this would be consistent with the 2

requirements also of 10 CFR 50 or 52 then in terms of 3

a safe shutdown condition.

4 MR. NOLAN: That's correct.

5 MEMBER KIRCHNER: Yeah. I noticed that 6

the GE used the, I think it's the IAEA language, they 7

talked about a safe state. But I suspect for the 8

staff, you would be looking for what's required as for 9

10 CFR 50 or 52.

10 MR. NOLAN: That's correct. And we 11 documented in our safety evaluation specifically the 12 interpretation that the staff has on GDC 27. And that 13 was pulled from the recent SECY paper that we wrote 14 where we specifically state the intent is, and it's a 15 first bullet here, you know, the intent is to maintain 16 long-term subcriticality using only safety-related 17 equipment.

18 MEMBER KIRCHNER: Excellent, thank you.

19 MR. NOLAN: Yup. Next slide. So GDC 28 20 requires that reactivity control systems be designed 21 with appropriate limits on the amount and rate of 22 reactivity increase to ensure that reactivity 23 accidents can neither damage the reactor pressure 24 boundary or disrupt the core or the internal 25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.

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52 structures to a point where it impairs significantly 1

the capability to cool the core.

2 These types of events are called out 3

specifically in GDC 28. Some of them include, you 4

know, rod ejection, rod dropout, things of that 5

nature. The topical report states that the BWRX-300 6

will meet GDC 28, and this is through a series of 7

design features of the control rod drive system in its 8

ability to limit the rate and amount of reactivity 9

increase, as well as a safety analysis which 10 demonstrates compliance with the requirement.

11 And so this analysis would look at control 12 rod drop accidents, and in the topical report GE has 13 committed to using, you know, existing approved 14 methodologies to perform that analysis. It's a 15 similar analysis which was performed for the ESBWR.

16 And so the staff found this approach to be consistent 17 with the GDC.

18 This is the final limitation and condition 19 specific to a control rod drop accident. Again, this 20 is really to document the staff's expectation that 21 this analysis be performed using design-basis 22 assumptions, as well as using approved methods. And 23 we tried to write some flexibility into this condition 24 as well.

25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.

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53 And so we provided also another option if 1

GE wants to go a different route that they could 2

demonstrate perhaps that the control rod accident is 3

a beyond-design-basis event and do a sort of a 4

different type of analysis and include that into 5

Chapter 19. Versus a, you know, more of a traditional 6

transient accident analysis, what we typically would 7

refer to as a Chapter 15 analysis.

8 And so that was just to establish sort of 9

expectations and provide some flexibility for the 10 future.

11 MEMBER MARCH-LEUBA: Is there a real need 12 to do that? I mean, we have all the methodology and 13 GEH knows how to do the rod drop calculations on a 14 cycle-specific basis. It doesn't save any money, it 15 doesn't make anything easier to try to change what 16 we're doing. In my opinion, yes, continue to do what 17 you're doing for operating reactors, which is every 18 cycle, just analyze the rod drop and do it.

19 MEMBER KIRCHNER: Yeah, just to add to 20 what Jose's saying, I would expect they're all -- that 21 the applicant, or GEH in particular here, I mean, 22 they're well experienced and must be totally up to 23 date on DG 1327, I don't remember what it now is as a 24 final reg guide, as Jose suggests. So it would seem 25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.

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54 to me that the path forward for expediting one's way 1

through the licensing review would be to stick with 2

the current rod drop analyses.

3 MR. NOLAN: Yes, I think the staff would 4

find that acceptable. The reason this is here is 5

really rooted in the way the original topical report 6

described this analysis, as well as some of the RAI 7

responses. And so we wanted to just be very clear of 8

what our expectation was that it be a design-basis 9

safety analysis, as well as I think GE proposes a one-10 time analysis to bound cycle-by-cycle variations.

11 But we wanted to clarify that it doesn't 12 have to do that. And I think we felt that this 13 condition provided that flexibility and clarification 14 that we needed to make the finding from a compliance 15 perspective.

16 MEMBER MARCH-LEUBA: I agree with you, 17 Ryan, that either way it satisfies regulations. But 18 the path of least resistance is do the calculation and 19 recycle. You know how to do it. It doesn't -- maybe 20 we'll GE in the closed session, but I don't think it 21 adds that much cost to the -- I would keep doing what 22 has worked for 60 years, and that's my personal 23 opinion. Thank you.

24 MR. NOLAN: Yup, and that's what we're 25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.

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55 trying to communicate here. We would certainly find 1

the traditional approach acceptable. Next slide, 2

Marieliz. Yeah.

3 So to conclude here, taking into account 4

the limitations in conditions, the topical report 5

provides an acceptable description of the 6

requirements, the acceptance criteria, and the 7

regulatory basis for the design feature specific to 8

the reactivity control functions for the BWRX-300.

9 And just as a disclaimer, we don't have 10 the application in front of us at this time, we don't 11 have the detailed design in front of us. And we will 12 evaluate full regulatory compliance at the time that 13 that application or other future licensing activities 14 are submitted to the staff. If an applicant can't 15 demonstrate compliance, you know, we do expect them to 16 justify an exemption to a regulation.

17 And with

that, that concludes my 18 presentation.

19 MEMBER MARCH-LEUBA: Great. Do we have 20 any questions for the staff in the open session? And 21 just a reminder, there's going to a GEH closed session 22 presentation, and there will not be a staff closed 23 session presentation, but they will be able to answer 24 questions if necessary.

25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.

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56 So any questions?

1 MEMBER KIRCHNER: Jose, this is Walt 2

again. This is not a question, maybe a statement.

3 I'm just thinking about the fine motion control rod 4

drives and the discussion we had. If indeed they wind 5

up down the road designing that system such that it 6

has one speed for normal rod withdrawal during normal 7

operation and a different speed for insertion, then 8

one -- just I'm thinking aloud a little bit here --

9 then one worries that there's the potential for the 10 system to not operate, function correctly and run the 11 rods out at the higher motor speed or however they 12 design it.

13 I'm, just an observation, something to 14 look at down the road when there's an actual design, 15 a detailed design.

16 MEMBER MARCH-LEUBA: We would be very 17 interested on that. But my suspicion is that the rod 18 ejection would be faster than the speed the motor can 19 move at. But and I will bound it.

20 MEMBER KIRCHNER: I agree, that would 21 likely bound it, you know, the traditional ejection or 22 drop in this case.

23 MEMBER MARCH-LEUBA: Yes. Okay, can we 24 open the public line please? For comments? Is the 25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.

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57 public phone line open for comments? Is anybody on 1

the public phone there, can you please say hello? I 2

don't hear anybody. So if there is anybody in the 3

public line that wants to make a comment, please state 4

your name and do the comment.

5 We'll leave the public line open for a 6

moment longer, and I'm going to ask the members if 7

anybody wants to make a statement around the table.

8 Remember that we will come back to the open line this 9

session to read the letter. But if you want to make 10 a comment on the record right now, that will be the 11 time.

12 Seeing no feedback, we are going to 13 temporarily recess this meeting, and we are going to 14 move to the closed team meeting, the closed phone line 15 to get the proprietary information. Everybody knows 16 that? Yes, sir.

17 CHAIR SUNSERI: No, I'm sorry, when you're 18 done, I had a question. I wanted to ask you about 19 timing and things.

20 MEMBER MARCH-LEUBA: Comment, go ahead, 21 I'm done.

22 CHAIR SUNSERI: Okay, so we're going to 23 recess here and go to closed session. I'm going to 24 suggest we take a 20-minute break and reconvene the 25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.

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58 closed session at 20 minutes before the hour, so 1

that'd be 3:40. How long do you think that closed 2

session is going to last? And I know it's just a 3

slag, but do you have an idea? Because we should give 4

the public an ideal of when we would return to the 5

open session approximately, so.

6 MEMBER MARCH-LEUBA: I believe, let me 7

make sure, --

8 CHAIR SUNSERI: Why don't we just say 9

4:30?

10 MEMBER MARCH-LEUBA: GE has provided 20 11 slides, but if we -- and I assume Charlie Hicks is 12 going to be doing it, okay, he likes to talk even more 13 than I do. But we can do -- let me make an executive 14 decision. We'll be back in the open line no earlier 15 than 4:30.

16 CHAIR SUNSERI: Okay.

17 MEMBER MARCH-LEUBA: That will give us --

18 CHAIR SUNSERI: Yeah, that's fine. That's 19 fine. That's good enough. And then we can have staff 20 monitor the 4:30 open line and let people --

21 (Simultaneous speaking.)

22 CHAIR SUNSERI: Yeah, okay, thank you.

23 MEMBER MARCH-LEUBA: So we are on recess, 24 and we will see everybody on the -- everybody that is 25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.

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59 allowed to be in the closed line at 3:40, that's 20 1

minutes from now.

2 CHAIR SUNSERI: Thank you.

3 MEMBER MARCH-LEUBA: So we are off the 4

open line record. We will still have a transcription 5

of the closed session at 3:40. We are on recess.

6 (Whereupon, the above-entitled matter went 7

off the record at 3:19 p.m.)

8 9

10 11 12 13 14 15 16 17 18 19 20 21 22 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

GE-Hitachi Nuclear Energy Michelle P. Catts GE-Hitachi Nuclear Energy Americas, LLC Senior Vice President, Nuclear Programs P.O. Box 780, M/C A-18 Wilmington, NC 28402 USA T 910.200.9836 Michelle.catts@ge.com M200153 November 24, 2020 U.S. Nuclear Regulatory Commission Document Control Desk Washington, D.C. 20555-0001

Subject:

Submittal of ACRS Full Committee Presentation Slides for NEDC-33912P, BWRX-300 Reactivity Control Licensing Topical Report Enclosed are the final presentation slides for use during the upcoming Advisory Committee on Reactor Safeguards (ACRS) GE-Hitachi Nuclear Energy Americas, LLC (GEH) Full Committee Meeting on December 1, 2020. This supports the ACRS review involving NEDC-33912P, BWRX-300 Reactivity Control, Revision 0, Supplement 1, and the corresponding NRC Advanced Safety Evaluation Report (SER) with No Open Items. contains non-proprietary information and may be made available to the public.

If you have any questions, please contact me at 910-200-9836.

Sincerely, Michelle P. Catts Senior Vice President, Nuclear Programs GE-Hitachi Nuclear Energy Americas, LLC

Enclosure:

1.

ACRS Full Committee Presentation Slides for NEDC-33912P, BWRX-300 Reactivity Control Licensing Topical Report - Non-Proprietary Information cc:

R Franovich, US NRC Document Components:

001 M200153 Cover Letter.pdf 002 M200153 Enclosure 1 Non-Proprietary.pdf

ENCLOSURE 1 M200153 ACRS Full Committee Presentation Slides for NEDC-33912P, BWRX-300 Reactivity Control Licensing Topical Report Non-Proprietary Information

ACRSFullCommitteePresentation GEHitachi(GEH)

LicensingTopicalReport(LTR)NEDC33912P BWRX300ReactivityControl (OpenSession)

December1,2020

Copyright 2020 GE Hitachi Nuclear Energy Americas, LLC - All Rights Reserved 2

PurposeofACRSFullCommitteePresentation

• DescribeDesignFeaturestoMeetRegulatoryRequirementsandProvide DefenseinDepthforLicensingBasisReactivityEvents

• Addressdesignrequirements,acceptancecriteria,andregulatorybasisfor theBWRX300ReactorProtectionSystem(RPS)andotherassociatedmeans for:

-ReactivityControl

-AnticipatedTransientsWithoutScram(ATWS)

• Providethedesignrequirements,acceptancecriteria,andregulatorybasis fortheBWRX300mitigatingsystemsassociatedwithanATWS

DefenseinDepthDesignFeatures forBWRX300ReactivityControl

Copyright 2020 GE Hitachi Nuclear Energy Americas, LLC - All Rights Reserved 4

DefenseinDepthDesignforBWRX300 BWRX300appliesadefenseindepthapproachalignedwithIAEA guidance

• AddressFundamentalSafetyFunctionstoensureoverallplantsafety

• AssignsBWRX300functionstoDefenseLinesassociatedwithFundamental SafetyFunctions

• ThisLTRisfocusedontheFundamentalSafetyFunctionofReactivityControl thatensuresdefenseindepthshutdowncapabilityandreactivitycontrol

Copyright 2020 GE Hitachi Nuclear Energy Americas, LLC - All Rights Reserved 5

DefenseinDepth-DefenseLine1 DefenseLine1:

• ReducechallengestotheReactorProtectionSystem(RPS)fromall occurrences

-Fewertripsperyear

-ReducesnumberofAnticipatedOperationalOccurrences(AOOs)

• ReducedchallengestoRPS

• SometransientsbecomeInfrequentEventsdefinedas<1per100Reactoryears

• StrengthensubsequentDefenseLines

-Quality

-Reliability

-Conservatism DefenseLine1(DL1)

IAEA Level1

Copyright 2020 GE Hitachi Nuclear Energy Americas, LLC - All Rights Reserved 6

BWRX300ReactorPressureVessel(RPV)

• LargeRPVsteamvolumeresultsinlower pressurizationrateforisolationevents (comparedtoABWRandexistingBWRs) resultinginlessreactivityeffect

• RefertoNEDC33910P,BWRX300Reactor PressureVesselIsolationandOverpressure Protection

Copyright 2020 GE Hitachi Nuclear Energy Americas, LLC - All Rights Reserved 7

DefenseinDepth-DefenseLine2 DefenseLine2:

• Includesfunctionswhichnormallycontroltheplant

-Rodcontrolandcontrolofpowergenerationsystems

• PlantfunctionsdesignedtocontrolorstopaPostulatedInitiating Event(PIE)

• MinimizesPIEsthatreachDL3setpointstherebyreducing challengestoDL3systems

• IndependentfromDL3

-Includesdiversemeansofshutdown

• Provideshighreliabilityofplantcontrol DefenseLine2(DL2)

IAEA Level2

Copyright 2020 GE Hitachi Nuclear Energy Americas, LLC - All Rights Reserved 8

BWRX300ControlRodwithFuelAssemblies ProvenBWRoperatingfleet ControlRoddesign Increasedclearancefor controlblades PositionedbyFineMotion ControlRodDrives(FMCRDs)

Copyright 2020 GE Hitachi Nuclear Energy Americas, LLC - All Rights Reserved 9

DefenseinDepth-DefenseLine3 DefenseLine3:

• IncludesfunctionswhichacttomitigateaPIE

-IsolationCondenserSystem(ICS)

• Ensureplantisplacedinasafestate

-ReactorProtectionSystem(RPS)Scram

• Assignedtohighestsafetyclass

• IndependentofDL2 DefenseLine3(DL3)

IAEA Level3

Copyright 2020 GE Hitachi Nuclear Energy Americas, LLC - All Rights Reserved 10 IsolationCondenserSystem(ICS)

• HeatexchangerdesignandcapacityofeachICS trainisthesameasESBWR

• Total%heatremovalcapacityfromICSlargerthan ESBWR

• Failsafe,simplesystem

• Limitsreactorpressureandtemperatureand maintainsreactorwaterinventory

• Condensatereturnvalves(notshown)failopenon lossofpowertothevalves

• Condensatereturnwellabovethecore

• ICSdesignenhancementsprovidespressure controlandassistsinpowerreduction

Copyright 2020 GE Hitachi Nuclear Energy Americas, LLC - All Rights Reserved 11 DefenseinDepth-DefenseLine4a DefenseLine4a:

• IncludesfunctionstomitigateaPIEalongwithfailureofDL3

• MitigatesCCFsinDL3

-AlternateRodInsertion(ARI)- provideshydraulicscramineventof HydraulicControlUnit(HCU)actuationfailure

-FMCRDinsertionwithmotors

• Ensuresplantisplacedinasafestate DefenseLine4a(DL4a)

IAEA Level4

Copyright 2020 GE Hitachi Nuclear Energy Americas, LLC - All Rights Reserved 12 DesignFeaturesRequiredbyATWSRule 10CFR50.62mandatesreductionofriskfromanATWS 10CFR50.62(c)(3),(4)and(5)requirethefollowingdesignfeatures forBWRs:

• ARISystem

• AutomaticStandbyLiquidControlSystem(SLCS)

• AutomaticRecirculationPumpTrip

Copyright 2020 GE Hitachi Nuclear Energy Americas, LLC - All Rights Reserved 13 10CFR50.62(c)(3)- AlternateRodInsertion(ARI)System

• Eachcontrolrodcanbeinsertedhydraulicallyusingstoredhighpressure waterfromhydrauliccontrolunit(HCU)accumulatorsbyeither:

-RPSanddiverseactuatedscramsolenoidvalvesremovingcontrolairtoeachHCU

-DiverseARIpilotvalvesremovingcontrolairtoscramsolenoidvalvesforallHCUs

• FineMotionControlRodDrives(FMCRDs)haveelectricmotordriven positioningusedforbothinsertionandwithdrawalofcontrolrods

• Electricmotordrivenpositioningdiversefromhydraulicscram

-Allowsrodmovement,evenwithfailureofARISystem

-UtilizesensorsandlogicthatarediverseandindependentofRPS

• Commoncausefailure(CCF)ofhydraulicscramcausedbyscramdischarge volumeusedinolderdesignsiseliminated

-ScramdischargefluidgoesintoReactorPressureVessel

Copyright 2020 GE Hitachi Nuclear Energy Americas, LLC - All Rights Reserved 14 10CFR50.62(c)(5)- AutomaticRecirculationPumpTrip ForcedcirculationBWRstriprecirculationpumpstoreducecore flowandpower:

BWRX300utilizesnaturalcirculationandhasnorecirculation pumps BWRX300designincorporates:

• Controlofpowergenerationsystemstoassistinmitigation

• Reductionofwaterlevel,coreflowandreactorpowerinasimilarmanneras recirculationpumptripinaforcedcirculationplant

Copyright 2020 GE Hitachi Nuclear Energy Americas, LLC - All Rights Reserved 15 DesignFeaturesDescribedinStandardReviewPlan(SRP)

NUREG0800,SRP15.8,states:

A.ForevolutionaryplantswheretheATWSruledoesnotexplicitlyrequireadiverse scramsystem,theapplicantmayprovideeitherofthefollowing:

i.Adiversescramsystemsatisfyingthedesignandqualityassurancecriteriaspecified inSRPSection7.2 ii.DemonstratethattheconsequencesofanATWSeventarewithinacceptablevalues BWRX300meetsbothrequirementsforanAOOwithfailuretoscram

• Alternatemeansforshutdown

• ARIandelectricmotorruninincludedinDL4a

• SuccessfulshutdownensuredbyDL2,DL3,DL4a

• Consequencesoffailuretoscramfromnormalanddiversemeansmitigatedbyuseof DL4a

Copyright 2020 GE Hitachi Nuclear Energy Americas, LLC - All Rights Reserved 16 RegulatoryAcceptanceCriteria

• PrimarySystem MaximumprimarystresswithinReactorCoolantPressure Boundary(RCPB)doesnotexceedtheemergencylimitsasdefinedinthe ASMEB&PVCode,SectionIII

• FuelIntegrity Claddingtemperatureandoxidationcriteriaof10CFR50.46 met

• ContainmentIntegrity Maximumcontainmentpressuredoesnotexceed thedesignpressure

• RadiologicalReleases Maintainedwithin10CFR100allowablelimit

• ShutdownandCooling Reactorisbroughttolongtermshutdownwith continuedeffectivecorecooling

Copyright 2020 GE Hitachi Nuclear Energy Americas, LLC - All Rights Reserved 17 10CFRPart50,AppendixA,GDC27

• 10CFRPart50,AppendixA,GDC27,CombinedReactivityControlSystems Capability Thereactivitycontrolsystemsshallbedesignedtohavea combinedcapability,inconjunctionwithpoisonadditionbytheemergency corecoolingsystem,ofreliablycontrollingreactivitychangestoassurethat underpostulatedaccidentconditionsandwithappropriatemarginforstuck rods,thecapabilitytocoolthecoreismaintained

-Exception Corecoolabilityismaintainedforlossofcoolantaccidentsbecause lossofwaterinventoryintheRPVisminimizedbytheassuredfunctionofRPV isolationvalvestomitigatelargelinebreaks RefertoNEDC33910P,BWRX300ReactorPressureVesselIsolationand OverpressureProtection

NRC Staff Presentation-GEH Topical Report NEDC-33912P, Revision 0, Supplement 1, BWRX-300 Reactivity Control BWRX-300 Small Modular Reactor ACRS Full Committee Meeting December 1, 2020

• NRC Staff Review Team

• BWRX-300 Background

• NRC Staff Review of NEDC-33912P

• Conclusion 2

Presentation Outline

NRR Nuclear Methods, Systems, and New Reactors Branch (SNRB)

Ryan Nolan

Andrew Proffitt

Alex Siwy NRR PRA Licensing Branch C (APLC)

Anne-Marie Grady

Alissa Neuhausen NRR Instrumentation and Controls Branch A (EICA)

Dinesh Taneja NRR New Reactor Licensing Branch (NRLB)

Rani Franovich 3

NRC Staff Review Team

• 300 megawatt electric small modular reactor

• Uses natural circulation and passive cooling isolation condenser system

Based on ESBWR design

• Uses typical boiling-water reactor bottom-entry, cruciform-shaped control rods

• Includes defense-in-depth and diverse features to ensure the capability to shut down and control the reactor

• NEDC-33912P specifies design requirements and assesses regulatory requirements related to reactivity control 4

BWRX-300 Background

NEDC-33912P specifies design requirements for:

• Rod control system

• Reactor protection system

• ((

))

• Alternate rod insertion

• ((

))

5 BWRX-300 Reactivity Control Systems and Functions

Evaluation of Applicable Regulations 10 CFR 50.62, Requirements for reduction of risk from ATWS events 10 CFR 50, Appendix A, General Design Criteria

GDC 12, Suppression of reactor power oscillations

GDC 20, Protection system functions

GDC 21, Protection system reliability and testability

GDC 22, Protection system independence

GDC 23, Protection system failure modes

GDC 24, Separation of protection and control systems

GDC 25, Protection system requirements for reactivity control malfunctions

GDC 26, Reactivity control system redundancy and capability

GDC 27, Combined reactivity control systems capability

GDC 28, Reactivity limits

GDC 29, Protection against anticipated operational occurrences 6

Evaluation of Applicable Regulations:

10 CFR 50.62

• NEDC-33912P, Section 3.7.1 defines the ATWS acceptance criteria for evaluating the effectiveness of the reactivity control diverse shutdown means:

RCS and main steam pressure below 120% design

Peak cladding temp. and oxidation within 10 CFR 50.46 limits

Peak containment pressure/temp. below design

Coolable geometry

Radiological doses are maintained within 10 CFR 100 limits

• Consistent with SRP Section 15.8, Anticipated Transients Without Scram.

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Evaluation of Applicable Regulations:

10 CFR 50.62(c)(3)

• Requires BWRs to have an ARI system diverse from the reactor trip system.

• The BWRX-300 includes an ARI system for diverse depressurization of the scram air header and will meet the requirement of 50.62(c)(3).

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Evaluation of Applicable Regulations:

10 CFR 50.62(c)(4)

• Requires BWRs to have a standby liquid control system (SLCS) for injection into the vessel.

• NEDC-33912P specifies the BWRX-300 will meet the risk goals of 10 CFR 50.62 for P(ATWS) less than 1x10-5 per reactor year (( )).

Diverse scram actuation logic

Diverse rod motive force

(( ))

• This risk goal is consistent with the intent of 10 CFR 50.62 (( ))

• Limitation and Condition 5.1 9

Evaluation of Applicable Regulations:

10 CFR 50.62(c)(4)

Limitation and Condition 5.1:

Any applicant referencing NEDC-33912P must perform and document:

• Reliability analysis or testing, considering applicable operating experience and expected load follow conditions, of the BWRX-300 diverse scram features to demonstrate the probability of an ATWS is less than 1x10-5 per reactor year (( )).

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Evaluation of Applicable Regulations 10 CFR 50.62(c)(5)

• Requires BWRs to automatically trip the recirculation pumps under ATWS conditions.

• This requirement is not applicable to the natural circulation BWRX-300.

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Evaluation of Applicable Regulations:

General Design Criterion 12

• Requires control and protection systems to ensure power oscillations that could exceed the SAFDLs are prevented or detected and suppressed.

• NEDC-33912P states the BWRX-300 will meet GDC 12 and maintains margin to instability through:

small core and orifice design

coupled power-flow response

RPV chimney

• Limitation and Condition 5.3 12

Evaluation of Applicable Regulations:

General Design Criterion 12 Limitation and Condition 5.3:

Any applicant referencing NEDC-33912P must perform and document:

• A stability analysis in accordance with an approved methodology to demonstrate that the BWRX-300 maintains a coupled power-flow response such that any operational perturbation, maneuver, or AOO that does not cause an immediate scram is naturally damped and decays quickly to steady state for all modes of operation; prevents SAFDLs from being exceeded; is not susceptible to regional or radial modes of oscillation; and includes necessary provisions to address cycle-specific conditions.

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Evaluation of Applicable Regulations:

General Design Criterion 26

• Requires two independent reactivity control systems of different design principles a)

The first must use control rods and is used for normal operation, including AOOs, with margin for malfunctions b)

The second must reliably control reactivity changes resulting from planned, normal power changes c)

One system must be capable of holding the reactor subcritical under cold conditions

• NEDC-33912P states that the BWRX-300 will meet GDC 26 by providing:

Control rods (satisfy a and c above)

Feedwater level control system at power, other means to adjust level in other modes (satisfies b above)

• NRC staff finds this approach consistent with GDC 26 14

Evaluation of Applicable Regulations:

General Design Criterion 27 The intent of GDC 27 is to require reactor designs to achieve and maintain long-term subcriticality using only safety-related equipment following a postulated accident with margin for stuck control rods.

NEDC-33912 proposes the following principal design criterion (PDC) in lieu of GDC 27:

The BWRX-300 reactivity control system shall be designed to have the capability of reliably controlling reactivity changes to assure that under postulated accident conditions and with appropriate margin for stuck rods the capability to cool the core is maintained.

BWRX-300 control blades will be capable of holding the reactor subcritical under cold conditions assuming failure of the highest worth control rod pair.

Analysis that demonstrates the control rod system is sufficient for achieving and maintaining shutdown margin could justify an exemption to GDC 27 and the use of the design-specific PDC.

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Evaluation of Applicable Regulations:

General Design Criterion 28 16 Requires reactivity control systems be designed with appropriate limits on the potential amount and rate of reactivity increase to assure that postulated reactivity accidents can neither:

1) result in damage to reactor pressure boundary greater than limited local yielding 2) sufficiently disturb the core, its support structures or other reactor pressure vessel internals to impair significantly the capability to cool the core.

Reactivity accidents that must be considered:

Rod ejection (unless prevented by positive means), rod dropout, steam line rupture, changes in coolant temperature/pressure, and cold water addition NEDC-33912P states that the BWRX-300 will meet GDC 28 by:

Design features of CRD system and rod control system limiting the amount and rate of reactivity increase

Safety analyses demonstrating compliance submitted in future licensing activities o

Including analysis of CRDA event using approved methodology (NEDE-33885P-A)

NRC staff finds this approach consistent with GDC 28

Evaluation of Applicable Regulations:

General Design Criterion 28 17 Limitation and Condition 5.2:

Any applicant referencing NEDC-33912P must perform and document:

A CRDA design-basis safety analysis applied to an equilibrium cycle in accordance with an approved methodology, providing justification for any deviations (e.g., performing a one-time analysis to bound cycle-by-cycle variations), or request an exemption to justify the CRDA as a beyond-design-basis event and document the CRDA analysis results in the probabilistic risk assessment.

Conclusion

• With specified Limitations and Conditions, NEDC-33912P provides an acceptable description of design requirements, acceptance criteria, and regulatory bases for design features of the BWRX-300 reactivity control functions.

• Detailed design of BWRX-300 SMR is not complete.

If applicant is not able to demonstrate compliance with NRC regulations, the applicant will be expected to justify an exemption from the applicable requirement.

NRC staff will evaluate regulatory compliance of the final BWRX-300 design with regards to reactivity control during future licensing activities for BWRX-300 applications.

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Questions?

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