ML24247A092
| ML24247A092 | |
| Person / Time | |
|---|---|
| Issue date: | 08/21/2024 |
| From: | Advisory Committee on Reactor Safeguards |
| To: | |
| References | |
| NRC-0016 | |
| Download: ML24247A092 (1) | |
Text
Official Transcript of Proceedings
NUCLEAR REGULATORY COMMISSION
Title:
Advisory Committee on Reactor Safeguards eVINCI Subcommittee
Docket Number: N/A
Location: teleconference
Date: 08-21-24
Work Order No.: NRC-0016 Pages 1-50
NEAL R. GROSS AND CO., INC.
Court Reporters and Transcribers 1716 14th Street, N.W.
Washington, D.C. 20009 (202) 234-4433 1
1
2
3 4 DISCLAIMER
5
6
7 UNITED STATES NUCLEAR REGULATORY COMMISSIONS
8 ADVISORY COMMITTEE ON REACTOR SAFEGUARDS
9
10
11 The contents of this transcript of the
12 proceeding of the United States Nuclear Regulatory
13 Commission Advisory Committee on Reactor Safeguards,
14 as reported herein, is a record of the discussions
15 recorded at the meeting.
16
17 This transcript has not been reviewed,
18 corrected, and edited, and it may contain
19 inaccuracies.
20
21
22
23
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(202) 234-4433 W ASHINGTON, D.C. 20005-3701 www.nealrgross.com 1
1 UNITED STATES OF AMERICA
2 NUCLEAR REGULATORY COMMISSION
3 + + + + +
4 ADVISORY COMMITTEE ON REACTOR SAFEGUARDS
5 (ACRS)
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7 eVINCI SUBCOMMITTEE
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9 WEDNESDAY
10 AUGUST 21, 2024
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12 The Subcommittee met via Teleconference,
13 at 1:00 p.m. EDT, Thomas E. Roberts, Chair, presiding.
14
15 COMMITTEE MEMBERS:
16 THOMAS E. ROBERTS, Chair
17 RONALD G. BALLINGER, Member
18 VICKI M. BIER, Member
19 VESNA B. DIMITRIJEVIC, Member
20 CRAIG A. HARRINGTON, Member
21 GREGORY H. HALNON, Member
22 WALTER L. KIRCHNER, Member
23 ROBERT P. MARTIN, Member
24 SCOTT P. PALMTAG, Member
25 MATTHEW W. SUNSERI, Member
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1 ACRS CONSULTANTS:
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6 DESIGNATED FEDERAL OFFICIAL:
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1 CONTENTS
2
3 Call to Order, Opening Remarks and Objectives.. 4
4 Tom Roberts, ACRS Subcommittee Chair
5 Staff Opening Remarks.............. 9
7 Reactor Design Overview Summary.........11
8 Anthony Schoedel, WEC...........11
9 Meredith Heh, WEC.............12
10 Principal Design Criteria Topical Report....25
11 Patrick Boyle, NRR............25
12 Greg Oberson, NRR.............27
13 Opportunity for Public Comment (None)......49
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1 P R O C E E D I N G S
2 (1:00 p.m.)
3 CHAIR ROBERTS: It is now 1:00 o'clock and
4 this meeting is called to order.
5 This is a meeting of the eVinci
6 Subcommittee of the Advisory Committee on Reactor
7 Safeguards.
8 I am Tom Roberts, Chair of today's
9 Subcommittee meeting.
10 ACRS members in attendance in person are
11 myself, Vicki Bier, Bob Martin, Ron Ballinger, and
12 Craig Harrington. Online, we have Greg Halnon, I can
13 see, and everybody else is off the screen.
14 So, if you could just identify the
15 members, or the members can identify themselves.
16 That's probably the way to do this.
17 MEMBER SUNSERI: Matt Sunseri is online.
18 Matt.
19 CHAIR ROBERTS: Matt Sunseri?
20 MEMBER SUNSERI: Yes.
21 MEMBER KIRCHNER: Walt Kirchner online.
22 MEMBER DIMITRIJEVIC: Vesna Dimitrijevic
23 is online.
24 CHAIR ROBERTS: Okay. Thank you, guys.
25 MEMBER HALNON: Greg Halnon is online.
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1 CHAIR ROBERTS: Okay.
2 And our consultants in the room are Steve
3 Schultz and Dennis. I see Dennis is online, Dennis
4 Bley.
5 So, if there is anybody who is either a
6 member or a consultant that I didn't introduce, please
7 speak up now.
8 (No response.)
9 Okay. Great.
10 Mr. Weidong Wang of the ACRS staff is the
11 Designated Federal Officer for today's meeting.
12 And no member conflicts of interest were
13 identified for today's meeting.
14 During today's meeting, the Subcommittee
15 will be doing a briefing on the Topical Report and the
16 staff's Draft Safety Evaluation for the Westinghouse
17 Principal Design Criteria, or PDC, Topical Report for
18 the eVinci Microreactor.
19 The PDCs are integral to the review of the
20 unique aspects of a nuclear power plant design. PDCs
21 aid in the NRC staff's evaluation of applicable
22 regulations that allow the NRC staff to assess with
23 reasonable assurance that advanced reactor technology
24 will be conform to the proposed design bases with
25 adequate margins of safety.
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1 We're reviewing this report today because
2 it serves as a foundation for the safety design
3 approach of the eVinci Microreactor. And I'll add
4 that this is the first, as far as I could tell, of the
5 microreactor or small reactor advanced reactor
6 designs. It's not a gas reactor or a sodium fast
7 reactor. So, it probably will be mentioned in this
8 hearing how you adapt it to what's written for those
9 different reactor technologies to what is really a
10 very different reactor technology.
11 And so, we're going to hear presentations
12 by the NRC staff and Westinghouse regarding this
13 matter.
14 A portion of the presentations by the
15 Applicant and the NRC staff may be closed to discuss
16 information that is proprietary to the Licensee and
17 contractors, pursuant to 5 U.S. Code 552b(c)(4).
18 Attendance at the meeting that deals with
19 such information will limited to the NRC staff and its
20 consultants, Westinghouse, and those individuals and
21 organizations who have entered into an appropriate
22 confidentiality agreement with them. Consequently, we
23 will then confirm that we have only eligible observers
24 and participants in the closed portion of the meeting.
25 So, per the schedule, we actually go into
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1 closed session in about an hour. So, at that point,
2 we'll take about a 15-minute break and the staff will
3 switch over the presentation to the closed
4 presentation and recognize folks, and we'll validate
5 everybody who is in is authorized to be in.
6 Okay. The ACRS was established by statute
7 and is governed by the Federal Advisory Committee Act,
8 FACA. The NRC implements FACA in accordance with
9 regulations found in Title 10 of the Code of Federal
10 Regulations, Part 7.
11 Per these regulations and the Committee's
12 Bylaws, the ACRS speaks only through its published
13 Letter Reports. We hold subcommittee meetings to
14 gather information for preparatory work as a part of
15 deliberations and final decisions on whether to issue
16 a Letter Report at a full Committee meeting. All
17 member comments should be regarded as the individual
18 opinion of that member only, not a Committee position.
19 The rules of participation in all ACRS
20 meetings, including today's, were announced in a June
21 13th, 2019, Federal Register Notice.
22 The ACRS section of the U.S. NRC public
23 website provides our Charter, Bylaws, member guidance,
24 subcommittee structure, agenda, Letter Reports, and
25 full transcripts of all full and subcommittee
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1 meetings, including the slides presented.
2 The meeting notice and agenda for this
3 meeting were published there and can easily be found
4 by typing "about us ACRS" in the search field of the
5 upper right corner of the website.
6 The ACRS, consistent with the agency's
7 value of public transparency in regulation of nuclear
8 facilities, provides opportunity for public input and
9 comment during these proceedings. We receive written
10 statements and requests to make an oral statement from
11 the public, and we have set aside time on the agenda
12 at the end of the meeting -- and that will be at the
13 end if the public part of the meeting -- for any
14 comments from members and the public listening into
15 this meeting. The Subcommittee will consider all
16 public comments, as appropriate.
17 A transcript of the meeting is being kept
18 and will be made available.
19 Today's meeting is being held in-person
20 and over Microsoft Teams for the ACRS staff, the
21 members, the NRC staff, Applicant, and members of the
22 public. The Teams link information with the telephone
23 bridge was placed on the agenda on the ACRS's public
24 website.
25 When addressing the Subcommittee,
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1 participants should first identify themselves, and
2 then, speak with sufficient clarity and volume, so
3 that they can readily be heard. When not speaking, we
4 request that participants mute your computer
5 microphone on Teams or the phone, if you're on the
6 bridge line, by pressing *6.
7 Please do not use any virtual meeting chat
8 features to conduct sidebar discussions related to the
9 presentations. Rather, limit use of the meeting chat
10 function to report IT problems, such as an inability
11 to hear speakers or see presentations.
12 Also, for everyone in the room, please put
13 all your electronic devices in silent mode, including
14 muting your speakers and microphone on your laptops.
15 In addition, please keep sidebar
16 discussions in the room to a minimum since the
17 microphones in the ceiling are live.
18 Finally, for the presenters, the
19 microphones at your tables are unidirectional. So,
20 you'll have to speak into the front of the microphone
21 in order to be heard online.
22 We're now proceeding with the meeting.
23 Does someone from the staff management want to start
24 off the meeting?
25 MR. PHILPOTT: Thank you. Yes.
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1 Good afternoon. My name is Steve
2 Philpott. I'm the Acting Chief of one of the Advanced
3 Reactor Licensing Branches in the Office of Nuclear
4 Reactor Regulation.
5 As Member Roberts mentioned, the purpose
6 of this Subcommittee meeting is to discuss
7 Westinghouse's Principal Design Criteria, or PDC,
8 Topical Report for the eVinci design. The PDC Topical
9 Report describes Westinghouse's development of the
10 Principal Design Criteria for the eVinci Microreactor.
11 Westinghouse developed these PDCs using the guidance
12 from Reg Guide 1.232, "Guidance for Developing
13 Principal Design Criteria for Non-Light Water
14 Reactors," which we often refer to as the Advanced
15 Reactor Design Criteria.
16 Westinghouse is implementing the Licensing
17 Modernization Project, or LMP, methodology in their
18 licensing approach and they use the LMP process and
19 the technology-inclusive content of the application
20 project guidance to risk-inform their PDCs.
21 Westinghouse has indicated that they
22 intend to apply this PDC Topical Report in support of
23 future Standard Design Certification applications and
24 potentially other licensing applications for the
25 eVinci Microreactor.
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1 We would like to express our thanks to the
2 ACRS, the Subcommittee, for taking the time and your
3 interest in reviewing this important topic.
4 I also want to thank the staff, NRC staff
5 and Westinghouse, for your time preparing for this
6 meeting and the presentations that the ACRS is going
7 to hear today.
8 I did want to add one additional note.
9 Our primary reviewer from the NRC staff is not feeling
10 well today. So, when we get to the NRC presentations,
11 we may need to adjust somewhat or we'll take it as it
12 comes.
13 Yes, so we look forward to the
14 conversation today. And if there are no other
15 questions, I'll turn it over to Westinghouse.
16 CHAIR ROBERTS: This would be a good
17 demonstration of defense-in-depth of the staff.
18 (Laughter.)
19 Can we turn it over to Westinghouse?
20 MR. SCHOEDEL: Yes, thank you, Member
21 Roberts.
22 My name is Anthony Schoedel, the Advanced
23 Reactor Licensing Manager at Westinghouse, supporting
24 eVinci Microreactor design licensing.
25 Thank you all for the time here today,
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1 yourself, Member Roberts, and the other Subcommittee
2 Members.
3 And thank you to the NRC participants for
4 the technical review today and support, and getting
5 ready for all these conversations.
6 You see a few of my colleagues here with
7 me. I'll let them introduce themselves as they share
8 the speaking presentation responsibilities throughout
9 the course of the dialog today.
10 First, you're going to hear from Meredith
11 Heh, at the end of the table. She's going to lead the
12 presentation/discussion for this open portion. I'll
13 be presenting the slides here on Teams.
14 And, Meredith, without any further ado,
15 once I get them up, I think the floor is yours.
16 MS. HEH: Thank you, Anthony.
17 As Anthony said, my name is Meredith Heh.
18 I'm Advanced Reactors Licensing Engineer for the
19 eVinci Microreactor project, and I'll be your lead
20 going through the open session today.
21 Great. So today, I will begin with a
22 design overview, and then, I will go through our
23 deployment model overview. Then, I will speak on our
24 NRC pre-application engagement to date, and then,
25 follow with an overview of the PDC Topical Report.
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1 And then, we can go to any questions that people may
2 have.
3 So here on this slide, you can see a good
4 overview of our eVinci Microreactor design. This
5 introduces safety through passive heat pipe
6 technology, and this enables a very low pressure
7 reactor.
8 So, you can see some of our key
9 components: the shutdown rods and control drums,
10 which provide diverse means for shutdown in the
11 reactor; the graphite core block, which is our
12 moderator. And the power of the reactor is a 15-
13 megawatt thermal with a fuel cycle of eight years, and
14 that fuel we'd be using is TRISO.
15 Our primary coolant is our heat pipes,
16 which is our new technology that you will hear more
17 about later today, as well as we will be using an
18 open-air Brayton cycle for power conversion. And you
19 can see the primary heat exchanger as another key
20 component in the diagram there.
21 Here on this slide, you can see an eVinci
22 Microreactor site layout. One key component we want
23 to address is that all buildings and systems are
24 aboveground. This means not a lot of excavation is
25 needed for our design.
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1 In the design, you can see our two-
2 reactor-bay system with the power conversion module in
3 the center of the two bays. And I will describe how
4 this system works on the next slide.
5 Out-front, you can also see three
6 containers. These will be for our I&C modules and our
7 battery module.
8 And another aspect I wanted to highlight
9 is our equipment is relatively small with less than
10 three quarters overall and the building footprint
11 being just a half an acre.
12 So, after, firstly, getting our test
13 reactor demonstrated for safety future performance,
14 this will help our licensing approval, and then, we
15 can deploy our reactor, as you can see on this screen.
16 We will start by assembling in a factory,
17 and then, we can transport disassembled to the site.
18 We will install and operate at the site, and this is
19 where the two reactor bays come in. You can install
20 and operate, and then, as that reactor is operating,
21 it will operate for eight years. And when that one is
22 no longer able to be operated, you can bring in the
23 second reactor, place it into the second reactor bay,
24 and allow for a plug-and-play situation, where you
25 remove one, and then, upload and start the next.
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1 Then, you can allow for that other first
2 reactor to cool down, and then, once it is cooled,
3 transport it away from the site. You can refuel and
4 refurbish that reactor, or if it has reached its end
5 of life, send it to decommissioning and the fuel to a
6 fuel storage facility.
7 This pre-application will be --
8 CHAIR ROBERTS: Meredith, I just have two
9 quick questions on radiation levels. It's not clear
10 from the figure in that slide how much shielding there
11 is in that blue building to keep the personnel safe in
12 this reactor.
13 It's also not clear on the next slide,
14 transport away from site, what kind of delays you need
15 before you can transport safely on the road.
16 Can you give us a little perspective on
17 that, on both of them?
18 MR. SMITH: This is Matt Smith from
19 Westinghouse.
20 So, in terms of shielding, there's
21 actually two structures shown there. There is a
22 concrete structure that provides the majority of the
23 shielding there, yes.
24 MS. SPALDING: I can talk about
25 transportation.
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1 MR. SMITH: Yes. Yes, I'll turn it over
2 to Amanda.
3 MS. SPALDING: Hi. This is Amanda
4 Spalding, also a part of the eVinci Microreactor
5 licensing team.
6 So, the question on transportation, we
7 will be certifying a reactor transportation cask for
8 the reactor module, both to ship onsite with the fresh
9 fuel and ship away with the spent fuel. And we will
10 make sure that it meets the Part 71 regulations for
11 fissile packages.
12 So, that cool-down period, while we're
13 still developing what that would actually look like,
14 it will be to ensure that we do meet the Part 71
15 regulations to ship it offsite.
16 CHAIR ROBERTS: Okay. Thank you.
17 MS. HEH: Thank you, Matt and Amanda.
18 There is some pre-application engagement
19 to date. Westinghouse has submitted 31 white papers
20 on various topics, including the second white paper
21 submitted being on the Principal Design Criteria
22 topic. And we have used this white paper to allow for
23 feedback and implementation into our Topical Report.
24 Speaking of Topical Reports, shown here
25 are the Topical Reports planned for submittal to the
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1 NRC, with a third -- six being submittal and a third
2 being the Principal Design Criteria Topical Report,
3 which was submitted in June of 2023.
4 So now, I'm going to go over our Topical
5 Report overview and going through the sections.
6 So, as I stated, the white paper feedback
7 on the PDC (audio interference) white paper was
8 heavily considered in our Topical Report development.
9 Section 1 of the Topical Report, the
10 purpose, states that it will cover the eVinci
11 Microreactor PDC and the basis for their selection.
12 This PDC includes safety-related and non-safety-
13 related with special treatment design criteria.
14 The derivation of the eVinci Microreactor
15 PDC were based on the following applicable regulations
16 and regulatory guidance:
17 The guidance for this design criteria
18 provided in Reg Guide 1.232.
19 The GDC and Title 10 of the CFR Part 50,
20 Appendix A.
21 And also, we incorporated the safety case
22 for the eVinci Microreactor developed based on
23 NEI 18-04 and NEI 21-07 guidance, which are endorsed
24 by the NRC in Reg Guide 1.233 and 1.253.
25 And then, at the end of this Section 1,
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1 Westinghouse requested NRC review and approval of the
2 set of PDCs for the eVinci Microreactor. This
3 included the list and justification for the GDC 4 identified as not applicable to the eVinci
5 Microreactor.
6 Okay. And then, Section 2 of the report,
7 there is a summary of the eVinci Microreactor design
8 and facility description, which is, basically, the
9 summary provided on slides 3 and 4 today.
10 Section 3 of the report, a PDC development
11 summary. The PDCs were derived based on the Design
12 Criteria Reg Guide 1.232 and GDC and 10 CFR Part 50,
13 Appendix A.
14 Each GDC and DC contained in Reg Guide
15 1.232 were reviewed for applicability to our design,
16 and they were either kept as is; they were edited, or
17 they were determined to not be applicable in entirety.
18 One additional PDC was developed not based
19 GDC or Reg Guide 1.232.
20 And the eVinci Microreactor PDCs are
21 function-based. They are not structure-, system-, or
22 component-specific. Therefore, there's no
23 differentiation or report between PDC required
24 function design criteria and PDC complementary design
25 criteria, which is described in NEI 21-07. And in a
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1 few slides, you'll be able to see the crosswalk of how
2 we either kept the PDC as is, edited, or determined to
3 not be applicable.
4 And continuing in Section 3, we discuss
5 how NEI 18-04 and NEI 21-07 were used to risk-inform
6 the PDCs and confirm the PDCs for the eVinci
7 Microreactor safety functions and confirm that they
8 were appropriately included.
9 Examples of the ways PDCs have been
10 improvised from NEI 18-04 and NEI 21-07. Some
11 examples here were:
12 We used quality assurance PDC tests from
13 NEI 21-07.
14 We allowed for the defense-in-depth
15 process to drive the need for multiple barriers.
16 "Important to safety" text was revised to
17 "safety-significant."
18 And "postulated accident" text was revised
19 to "licensing basis events" or "design-basis
20 accidents," as applicable.
21 Table 3.3-1 in the Topical Report is shown
22 here, which is our PDC crosswalk. You can see the
23 list of applicable GDCs and whether they were pulled
24 from which appendices in Reg Guide 1.232, and whether
25 they were modified, identical, or not applicable to
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1 the eVinci design.
2 This brings us to Section 4 of the report,
3 which is the eVinci Microreactor PDC list. As stated
4 right before the tables, each table consists of a
5 title, which is the number and title of PDC, and which
6 of those cases comes from the 10 CFR Part 50, Appendix
7 A, or Reg Guide 1.232. And the event you can see is
8 provided, the actual wording of the text.
9 Then, our position, which provides the
10 determination of whether a given ARDC, SFRDC, or
11 MHTGR-DC from Reg Guide 1.232 is adopted with or
12 without changes.
13 Modifications to the text are made in red
14 with strikeout or blue with underline for added text.
15 And then, a basis is provided which
16 provides justification and rationale for why certain
17 design criteria were determined to be applicable, and
18 also, justifies and describes changes to the text.
19 And finally, the source is provided.
20 So, we have a few examples. The first is
21 an example of one PDC that was modified from the ARDC
22 language with changes consistent to what is in
23 NEI 21-07. And this is our first PDC quality
24 standard.
25 Our second example is our one and only
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1 newly-developed PDC for monitoring and testing. And
2 this combined multiple PDCs into a single PDC for
3 these functions.
4 Another example here is an example PDC
5 which is identical to Reg Guide 1.232. This is PDC 14
6 for reactor helium pressure boundary.
7 And finally, an example of the PDC which
8 is not applicable. The objective of PDC 27, combined
9 reactivity control system capability, as satisfied by
10 PDC 26 for reactivity control.
11 CHAIR ROBERTS: I guess I have two
12 questions, and if you want to defer them to the closed
13 session, let me know. We can do that.
14 But it's a little surprising, given that
15 this is a heat pipe reactor, which is not what was
16 really considered when either Appendix B or C of the
17 Reg Guide were written. I guess Appendix A was
18 intended to be generic.
19 You have a lot of you picked from this
20 Appendix and picked from that Appendix. But Design
21 Criteria 6, which is really a combination of a bunch
22 of others; it's not really unique to the heat pipe
23 reactor. There's nothing in here that seems to be
24 unique to a heat pipe reactor.
25 And part of the Reg Guide requirements are
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1 to address unique features of your design and
2 determine whether or not there are design criteria
3 that are warranted based on that design.
4 So, I was wondering your perspective on,
5 you know, why is it that all of the criteria that
6 apply to a heat pipe reactor are radically covered by
7 a document that really wasn't written for a heat pipe
8 reactor?
9 MS. SPALDING: Yes. So, this is Amanda
10 Spalding again.
11 And I think we'll go into this a little
12 bit more in the closed session. But what I can share
13 here, as Meredith mentioned earlier in her
14 presentation, we developed our PDC to be based on
15 function and not specific SSCs. And so, as we went
16 through the criteria in Reg Guide 1.232 and the GDC,
17 we didn't identify any additional functions or safety
18 functions for our reactor that were not already
19 covered. And while there may be different components
20 or different systems that will perform those
21 functions, there were no additional functions.
22 So, I think that's maybe where the
23 difference is. You know, we did look at our design,
24 but we really looked at it as, what are the safety
25 functions being performed and are those covered by the
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1 intent of the design criteria?
2 We can discuss that more in the closed
3 session, but I think, for this portion, that's what we
4 would like to say now.
5 CHAIR ROBERTS: Okay. Thanks. That
6 sounds good
7 MS. SPALDING: Yes.
8 CHAIR ROBERTS: There probably will be
9 more questions in the closed session.
10 And then, the second question I had -- and
11 again, if you want to comment in your closed session,
12 that's fine -- but there were several design criteria
13 that have specific requirements for redundancy,
14 defense-in-depth, diversity, those types of things.
15 And you pretty universally change those to follow the
16 LMP core process. That will tell you whether or not
17 you need such diversity.
18 I was wondering just in general, are you
19 convinced that the LMP really covers all that or is
20 there some qualitative aspect of the LMP you're
21 counting on to identify things that may not be fully
22 modeled by the PRA?
23 MS. SPALDING: Yes, that's another great
24 question. And I think, again, we'll cover it a little
25 bit more in the closed portion; specifically, when
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1 Matt covers some discussion design overview.
2 But our goal was to not have prescriptive
3 requirements through the PDC and allow the LMP process
4 to drive what's really necessary. So, I think, to
5 answer your question, no, we don't necessarily
6 anticipate that there are things that the PRA won't
7 identify, where the LMP process will not identify true
8 defense-in-depth adequacy, where we would need
9 redundancy or diversity. So, we're allowing that
10 process to drive the specific SSCs that will perform
11 the functions.
12 But again, we can discuss that more in the
13 closed session.
14 CHAIR ROBERTS: Okay. Good. Thanks.
15 Any other questions from members or
16 consultants before we go to the staff open session?
17 (No response.)
18 Okay. Hearing none, let's go ahead and
19 change out to the staff. You can go to the
20 presentation.
21 Your choice, you can stay back there or
22 move up to the table.
23 If you like, you can sit in the audience
24 until we start the closed session.
25 MS. SPALDING: We won't be in the hot seat
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1 anymore.
2 CHAIR ROBERTS: Are you ready? Okay, go
3 ahead.
4 MR. BOYLE: Okay. Great. Thank you.
5 Good afternoon. I'm Patrick Boyle,
6 Licensing Project Manager at the NRC assigned to the
7 Westinghouse Electric Company eVinci project. I'm the
8 lead Project Manager for the review that Westinghouse
9 has for the Design Criteria Topical Report.
10 So today, we had Dan Beacon scheduled. He
11 is, unfortunately, unable to join us. So, Greg
12 Oberson is his Branch Chief and will be taking us
13 through the technical details of the discussion.
14 We did review our slides and determine
15 that we may require additional time in the open
16 session because in this area we can cover, and then,
17 we will be able to save that time in the closed
18 session.
19 This slide describes the agenda for the
20 NRC staff's presentation today:
21 Review the chronology of the staff's
22 review.
23 The purpose of the staff's review.
24 The staff's strategy on the Topical
25 Report.
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1 We will provide an overview of the
2 contents of the Safety Evaluation Report.
3 And then, summarize the NRC staff's
4 conclusion regarding the Westinghouse PDC Topical
5 Report.
6 Regarding the timeline of the review,
7 Westinghouse submitted Revision 0 of the Topical
8 Report in June 2023.
9 Staff accepted the Topical Report review
10 and began the staff's review in August of 2023.
11 The staff conducted clarification meetings
12 from September to October 2023.
13 Following the clarification meetings, the
14 staff issued requests for additional information in
15 November of 2023.
16 Westinghouse responded to those questions
17 in December.
18 And then, in May, Westinghouse submitted
19 Revision 1 to the PDC incorporating the RAI responses,
20 as well as the information from the clarification
21 meetings.
22 The Draft Safety Evaluation for the PDC
23 will be issued in July of 2025.
24 And now, I'd like to turn this over to
25 Greg Oberson for the technical details of the PDC
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1 review.
2 MR. OBERSON: All right. So, as
3 mentioned, I'm Greg Oberson. I'm the Branch Chief of
4 Advanced Reactor Technical Branch 1, the Division of
5 Advanced Reactors, Nonpower Production and Utilization
6 Facilities.
7 So, I just want to, I guess, start by
8 acknowledging or sort of exercising what was aptly
9 mentioned, our defense-in-depth. So, in this case,
10 maybe the capability of the subsequent layers diminish
11 relative to the first layer -- in this case, Dan. So,
12 I'm not going to attempt it. If you could just bear
13 with me and us to appropriately replicate, and Dan
14 would add more to the presentation. So, I'm going to
15 sort of hop scotch through it.
16 But I think the important things are we
17 want to get the record of the meeting; we want to get
18 any input that you guys have had in response to what
19 you received from Westinghouse or in your prep prior
20 to the meeting. Keep note of that. And what we can
21 address here, we will, and what we can't, we'll get
22 back, and then, work through it that way.
23 So, in light of that, some things I'll
24 just sort of skip through relatively quickly. Other
25 things which I think I can somewhat capably speak to,
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1 I will. Other things which are sort of beyond me at
2 this moment, I'm going to have to defer. So, as
3 mentioned, I just appreciate your forbearance. We'll
4 do our best to do this.
5 As is obvious, the purpose of the Topical
6 Report was already well-stated. So, I don't intend to
7 just restate what was already said. But I will speak
8 to our review strategy, which was, generally, to
9 review the conformance with the Regulatory Guide
10 1.232, which was already mentioned in the prior
11 presentation by Westinghouse.
12 And notably, evaluate deviations from or
13 changes from Reg Guide 1.232. And in recognition of
14 key eVinci design features, again, as has already been
15 mentioned, this is a difference in the reactor than
16 what was perhaps envisioned when that Regulatory Guide
17 was developed. And therefore, it is necessary and
18 appropriate to look at eVinci in the context of that
19 fact.
20 And then, sort of correlated to that,
21 consider the applicability of the Appendices and
22 guidance, the novel design features, and where they
23 are appropriate, make note of that, and where there
24 are differences or key differences, make note of that
25 as well.
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1 Go to the next slide.
2 So, this is just the Safety Evaluation
3 overview. Again, I won't belabor the point here, but
4 what we noted was that the Regulatory Guide, the
5 regulations and guidance that we referenced in making
6 the Safety Evaluation findings.
7 eVinci did provide design information in
8 the Topical Report, but that was not reviewed by the
9 staff, nor did staff make any findings on the adequacy
10 of the design itself. So, we consider that to be
11 informational in the context of not supporting the
12 more fundamental evaluation of the PDCs.
13 And then, in light of what I just
14 mentioned, we sort of did the PDCs in terms of the way
15 we wrote the SE, in terms of the ones that were,
16 essentially, in Reg Guide 1.232. That's one category.
17 Another category would be those that are
18 were influenced by NEI 18-04, terminology and
19 approach, following up on what you heard this morning.
20 There are some unique ones -- fuel
21 storage, given the design concept, and then, a few
22 odds and ends that we think warrant specific attention
23 that we'll speak to.
24 And then, we noted again, as was mentioned
25 by Westinghouse staff, where there were design
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1 criteria that were not found to be applicable to the
2 design of those.
3 And then, we'll speak to the limitations
4 and conditions.
5 So again, I won't take a lot of time in
6 restating this. I believe the members and the
7 participants in the meeting are aware of the
8 regulations and 10 CFR Parts 50 and 52 that relate to
9 the provision of PDCs, and as well, as noted, in
10 10 CFR Part 50, Appendix A, as it concerns light water
11 reactors. And again, this having been sort of stated
12 prior, I won't stick on this slide.
13 So, you can go ahead, Patrick.
14 And I'll take the same general approach
15 for this one, as these have been previously noted. Of
16 course, we view Reg Guide 1.232 as sort of like, you
17 know, base level of beyond the regulations themselves
18 and based on what we'll reference.
19 With the PDC reviews, we are sort of
20 overlaid with that. The advanced reactor technology
21 was the risk-informed regulatory guidance that relates
22 to the limitation of the LMP methodology on the
23 technology, the application of methodology, and so
24 forth, as has been previously mentioned by
25 Westinghouse in the context of other PDC reviews that
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1 you guys have done.
2 So, eVinci did a great job of these in the
3 prior presentation. But, more particularly, once we
4 go to closed session, we will speak to the eVinci
5 design features.
6 But I did want to make note of a few
7 things here that we think are relevant to the
8 consideration when we think about the applicability of
9 the PDCs to Reg Guide 1.232 to the eVinci design
10 itself. Obviously, the very fact of having TRISO fuel
11 gives it some similarity to those designs referenced
12 in Reg Guide 1.232 that also consider TRISO fuel.
13 Skipping, I guess, to the fourth bullet,
14 the heat pipe I guess maybe could be considered a
15 different design feature than what was explicitly in
16 Reg Guide 1.232. So, that warrants noting.
17 Passive heat removal. The reactor heat
18 controls functional (audio interference) is something
19 that we'll speak to, and then, the notion that a lack
20 of electrical power that is necessary to perform the
21 required safety functions, and then, maybe the very
22 last point, the transportable design. Again, there
23 are PDCs related to that, that would have not been
24 explicitly addressed in Reg Guide 1.232. It's
25 warranted to give consideration to those in our
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1 evaluation.
2 So, as was mentioned -- it sort of came up
3 in that prior discussion by Westinghouse already --
4 given that the eVinci heat pipe reactor design itself
5 was not one that was explicitly given consideration to
6 in Reg Guide 1.232, it becomes sort of a mix and match
7 of how you sort of translate Reg Guide 1.232 today
8 relative to the eVinci design.
9 There are some aspects I think that we
10 view as being similar, at least conceptually, to the
11 SFRDCs insofar as it's sodium; it's contained within
12 the heat pipes. There are other aspects that are
13 perhaps akin to the high temperature gas reactor
14 design. You know, we note the fuel functional
15 containment and the materials, graphite, and so forth.
16 There's some similarities there, as was already
17 mentioned. PDC 6 is sort of one that rules and
18 another batch of PDCs or generic PDCs from Reg Guide
19 1.232.
20 So, as was mentioned, we sort of did the
21 PDCs into different categories, in part, due to how
22 similar we believe they are to what was in Reg Guide
23 1.232 -- again, comparing what are the functions or
24 the features of the eVinci design and how those relate
25 to some of the assumptions that are made in the
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1 reactors of this sort that were evaluated in analysis
2 for Reg Guide 1.232.
3 Listed here on this slide are a number of
4 PDCs which we found to be, essentially, identical to
5 1.232, where the language is, essentially, well,
6 verbatim the same or perhaps a wording change, as
7 noted there, "systems" to "SSCs," that we believe does
8 not have any meaningful change to the intent of the
9 allocation of the PDCs.
10 What we confirmed for the PDCs is, again,
11 at least on a functional basis, there was a direct
12 correlation between the eVinci approach and the Reg
13 Guide 1.232 sort of generic evaluation, such that we
14 could say that the bases for determining that the PDCs
15 were adequate as they relate to the designs in the
16 1.232 continue and apply to the eVinci design itself.
17 So, a number of PDCs as well concerned the
18 changes, or perhaps supporting changes, related to the
19 implementation of the LMP terminology. And this is
20 very similar to what came up this morning in the
21 discussion with the other vendor about the application
22 of the LMP to their PDCs.
23 We do note that Reg Guide 1.233, that it
24 states the applicants -- referencing the Reg Guide --
25 are expected to use the technology of NEI 18-04, and
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1 as such, we see changes -- for instance, from
2 "important to safety" in the Reg Guide to "safety-
3 significant," for instance, in licensing basis events
4 -- so as to align with the language from NEI 18-04.
5 And consequently, again, the obligation
6 for staff would be to confirm that, notwithstanding
7 the wording changes, the intent of the PDC remains the
8 same from the evaluated wording in Reg Guide 1.232 to
9 the eVinci design. And in the cases referenced, the
10 staff determined that those still didn't apply, and as
11 such, the PDCs can be determined to be acceptable.
12 So again, and continuing on with the PDCs
13 influenced by the approach, it may be worth noting
14 that Reg Guide 1.25 really was a draft at the time
15 that the Topical Report was drafted. So, the
16 refinement of PDCs into RFDCs and CDCs was not
17 implemented in this report.
18 The NEI 18-04 approach included an
19 evaluation of defense-in-depth adequacy intended to
20 address concerns related to independent redundancy,
21 diversity, and defense-in-depth, and see the Reg Guide
22 1.232 language regarding this concepts was, therefore,
23 removed. But we note that it's only acceptable if
24 used with the LMP licensing approach.
25 And, you know, once we get to the
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1 discussion of the licensing -- sorry -- the
2 limitations and conditions, we can speak more
3 specifically to the intent of the condition as it
4 relates to the implementation of LMP methodology.
5 Okay. So, as it relates to the design of
6 the microreactor concerning the transportability, I
7 guess, or storage or transportability of the reactor
8 itself, the microreactor, there are a few PDCs -- 61,
9 62, and 63 -- that modify the language to reflect
10 reactor fuel handling and storage demand for the
11 eVinci design. So, they replace concepts of fuel
12 storage, waste, and handling with the concept of
13 reactor storage, at least as we understand it, to
14 reflect the fueled reactor unit deployment and the
15 handling approach being sought for implementation, or
16 at least being considered in the eVinci deployment
17 model.
18 It's worth noting -- and just for the
19 record, I believe the Committee is already aware of
20 this -- staff have provided a SECY paper to the
21 Commission that concerns a number of matters related
22 to technical and regulatory dimensions of fueled
23 reactor handling and storage that remain at this
24 point, from our perspective, appropriately the
25 Commission's decisionmaking process. And therefore,
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1 we would condition the PDCs on the outcome of the
2 Commission's policymaking, and then, the demonstration
3 eventually of conformance with whatever that policy
4 happens to be.
5 So, we're sort of kicking the can here,
6 effectively, until we get further direction from the
7 Commission as far as what this is going to look like
8 for the fueled reactor, like reactor deployment.
9 So, I think this sort of gets into the few
10 PDCs where just we wanted to bring it back to the
11 Committee's attention to matters where we sort of
12 evaluated, I guess, where there are some unique
13 aspects we wanted to bring the Committee's attention
14 to. They don't fit quite into the other categories
15 that we already mentioned.
16 So, PDC 12 combines portions of Reg Guide
17 1.232, Appendix A and C, and this is the suppression
18 of power oscillations. So, this reflects a broader
19 applicability of SSCs than ARDC 12, including the
20 reactor core structures, coolant control and
21 protection system. So, it reflects the use of SARRDLs
22 consistent with DC 12 rather than SAFDLs, in part,
23 because of the similarity of fuel design and
24 radionuclide retention approach for TRISO fuel. And
25 we found that to be applicable to the design and that
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1 the underlying intent of what was evaluated in Reg
2 Guide 1.232 is applicable to the eVinci design.
3 This one may be best left for the closed
4 discussion of PDC 17. We do the same for this one,
5 microreactor control.
6 So, PDC 64, we're monitoring radioactive
7 releases. Changes to the Reg Guide reflect the
8 functional containment approach and LMP terminology.
9 So, Revision 0 of the Reg Guide included additional
10 specificity with undefined terminology. We had a
11 public meeting, and then, there was a revision to
12 PDC 64 to more closely align with ARDC 64. And again,
13 we found that the intent and underlying safety basis
14 aligns with the Regulatory Guide.
15 PDC 71 is adapted from Reg Guide 1.232,
16 Appendix B, in this case, akin to the sodium fast
17 reactor design criteria. So, applicability is to
18 helium cover gas purity of the eVinci reactor
19 canister. So, we removed, in light of eVinci design
20 language referred to the sodium primary coolant, and
21 note that eVinci PDC 73 pertains to the detection of
22 sodium (audio interference) or reactions from sealed
23 heat pipes. So, the PDC on primary cover gas purity
24 and underlying safety basis aligns with Reg Guide
25 1.232 in the context of eVinci.
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1 PDC 73, sodium detection and reaction
2 prevention and mitigation. This is adapted, again,
3 from one of the SFR design criteria. It expands upon
4 that with the requirement to assure passive heat
5 removal system availability, and the language
6 regarding sodium-concrete interactions is removed.
7 There are multiple non-concrete barriers between the
8 sodium contained in the heat pipes and the concrete
9 structures outside the reactor canister or primary
10 heat exchanger. And as such, again, the intent of the
11 safety basis aligns with Reg Guide 1.232.
12 So, PDC 74 adopts the applicable portion
13 of Reg Guide 1.232, Appendix B, language regarding
14 steam-water energy conversion systems. These are
15 grouped because eVinci relies on an open-air Brayton
16 conversion system, as was discussed in the
17 Westinghouse portion of the presentation. And again,
18 the underlying safety basis aligns with Reg Guide
19 1.232 and remains applicable in the context of the
20 design.
21 Let's see. PDC 78, sodium heat pipe
22 interactions. Again, this is adapted from the SFR
23 design criteria, and changes, as staff noted, reflect
24 that sodium is only contained in pipes and not as a,
25 quote-unquote, "primary coolant." The language is
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1 adapted, again, to reflect the use of the LMP
2 methodology and the defense-in-depth adequacy
3 assessment.
4 You can go on, Patrick.
5 So, I think now we'll speak to the PDCs --
6 I'm sorry -- the PDCS from Reg Guide 1.232 and the
7 design criteria that were not applicable and our
8 reasoning for that.
9 So, there are a number of PDCs related to
10 the monitoring section that were included in Reg Guide
11 1.232. And it was already mentioned that these sort
12 of get encompassed or rolled into a higher level.
13 PDC 6 may be seen as saying they don't
14 apply, but they do apply. But they are sort of rolled
15 together into a single PDC that concerns, again, the
16 capacity and monitoring, inspection and testing. So,
17 the intent in the underlying safety basis for all PDCs
18 were sort of coalesced into PDC 6. Staff assured that
19 those are appropriately addressed.
20 So, heat transport functions. So, PDCs
21 30, 31, and 33, these are not directly applicable to
22 the heat design of the eVinci reactor. Specifically,
23 the designers refer to a reactor coolant system, but
24 the staff interpretation of Reg Guide 1.232 is that
25 the eVinci design does not include any forced
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1 convection or primary coolant as what would have been
2 meant in that regulatory guidance.
3 But, nevertheless, we did want to ensure
4 that the fundamental safety concepts or intent that
5 are meant to be addressed by those design criteria
6 were sufficiently addressed by PDCs. So, for example,
7 the reactor coolant system, we can kind of look at the
8 reactor canister, that helium pressure boundary, and
9 like can conclude for ourselves that the intent of
10 those is addressed by other aspects of the design.
11 Let's see. Heat removal emergency
12 cooling. So, these focus on adequate heat removal
13 capability to cool the core containment and associated
14 SSCs. I'll be honest, I don't know what was meant by
15 this. So, if there are any questions on that, I'll
16 have to take that back. Apologies for that.
17 The functional containment. This has
18 already been addressed, and I think Dan had mentioned
19 that this would be appropriate to address in the
20 closed session. So, we'll pick up the conversation
21 from there.
22 So, as far as limitations and conditions
23 go, you know, there's a couple proposed here, and I
24 won't read those verbatim. You have those at hand for
25 you.
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1 So, a couple of them refer to the
2 implementation of LMP methodology, recognizing, again,
3 as we've already discussed, that these are preliminary
4 designs, and as the LMP process continues to unfold,
5 as necessary, we will ensure that the outcomes of
6 those are iterated back into for the development of
7 the PDCs; and also, that to the degree that sort of
8 language related to implementation of the PDC reflects
9 terminology from the LMP and departures from, for
10 instance, Reg Guide 1.232, that those are acceptable
11 insofar as the user of the Reg Guide -- I'm sorry --
12 the user of the Topical Report conforms with the LMP
13 process.
14 Let's see. Then, the third one relates,
15 again, to the matters of reactor fuel storage and
16 transportation --
17 CHAIR ROBERTS: Excuse me. Could you go
18 back?
19 MR. OBERSON: Sure.
20 CHAIR ROBERTS: Yes, there's two questions
21 that may be editorial, maybe not. But the second
22 sentence of the first one says, "design changes and
23 associated policy implementations." And it seems like
24 from the first sentence, it's the LMP implementation
25 of the entire design, not just the changes that are
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1 made to the design, is that right?
2 MR. OBERSON: Yes.
3 CHAIR ROBERTS: It seems the word
4 "associated" doesn't belong there.
5 MR. OBERSON: Yes, we may have to check
6 that wording out. I think the intent of that,
7 fundamentally, is to ensure that, if the LMP had a
8 limitation, it doesn't necessitate a revision to the
9 PDCs in whatever manner. We would have assurance that
10 those would be, like I said, that those would be
11 accounted for. So, yes, we'll take a note, a project
12 to take a look at the wording and see. Thank you for
13 drawing the attention to that.
14 CHAIR ROBERTS: Yes. And the second one
15 is No. 2, why isn't PDC 16 listed there?
16 MR. OBERSON: Again, I'll have to take a
17 note of that to follow back up with you on that.
18 CHAIR ROBERTS: So, that's a functional
19 containment --
20 MR. OBERSON: Yes.
21 CHAIR ROBERTS: -- and the words were
22 taken out about how to --
23 MR. OBERSON: Yes. Dan, again, if you
24 want to join? I apologize, Dan, I'm not doing you
25 justice to what you can do here.
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1 MR. BEACON: Oh, that's no problem. I
2 snuck back into the meeting from my hotel real quick.
3 So, I think our position is that we do
4 plan to put 16 into that list.
5 MR. OBERSON: So, as you heard, it was not
6 included. That was an oversight or change in --
7 CHAIR ROBERTS: Okay. Thanks. So, 16
8 will be added, too? Okay, great. Thank you.
9 MR. OBERSON: Thank you, Dan.
10 Let's see. So, circling back, I mentioned
11 the one on the -- go to the next one, Patrick. Yes,
12 I mentioned the one on the Commission policy on
13 microreactor deployment and the fourth one. That's
14 one, I think, for the closed session.
15 So, in conclusion, Westinghouse considered
16 each of the design aspects presented in Reg Guide
17 1.232 and a sufficient set of PDCs for the eVinci
18 design. The core subject is the license limitations
19 and conditions. From the perspective of staff, they
20 established the necessary design testing and
21 performance and provided reasonable assurance that the
22 reactor could be operated without undue risk to the
23 health and safety of the public, and in general, that
24 the TR is suitable for referencing any future license
25 applications.
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1 So again, I do apologize for, like I said,
2 any lack of capacity that I have to address any
3 matters you would have wanted to discuss, but I'm
4 happy to take any questions that I can, and otherwise,
5 pick it up for those matters that are moving to the
6 closed session.
7 Thanks.
8 CHAIR ROBERTS: Yes, adding PDC 16 to that
9 policy No. 2 is a good one. We had a pretty extensive
10 discussion this morning on a different PDC review and
11 it was very similar changes made.
12 MR. OBERSON: Sure.
13 CHAIR ROBERTS: Then, the question was,
14 why the PDC would be written specifically saying use
15 TRISO fuel, which gives you sufficient, you know,
16 containment --
17 MR. OBERSON: Sure.
18 CHAIR ROBERTS: -- versus keeping the
19 functional type of requirement of partial containment
20 that says have multiple barriers and show that. So,
21 maybe you see that as more the generic question for
22 both of these projects --
23 MR. OBERSON: Sure.
24 CHAIR ROBERTS: -- when you're rethinking
25 the desirability of having a more detailed design
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1 specification as opposed to at the more functional
2 level.
3 MR. OBERSON: Yes. Okay.
4 CHAIR ROBERTS: Okay, great. I guess you
5 know this portion of it?
6 MR. OBERSON: Yes, I got you. Thanks so
7 much. Yes.
8 CHAIR ROBERTS: Okay. Any other questions
9 from members or consultants?
10 MEMBER HALNON: This is Greg. I have one
11 quick one.
12 MEMBER KIRCHNER: Tom?
13 MEMBER HALNON: Go ahead, Walt.
14 MEMBER KIRCHNER: Do you want to go first?
15 MEMBER HALNON: Well, go ahead, Walt. I'm
16 fine.
17 MEMBER KIRCHNER: Tom, yes. Thank you.
18 This is Walt Kirchner.
19 Actually, I wanted to ask the staff about
20 how they were handling -- there's some unique aspects
21 to this design and you addressed one of them earlier.
22 The sodium coolant is really not a primary coolant as
23 we think of it. It's part of a heat pipe system.
24 But the challenge that I see isn't so much
25 that as the fact that the reactor container does not
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1 completely encapsulate the sodium. So, you have the
2 heat pipes going out from the container to the air
3 Brayton cycle system.
4 So, then, it raises the question of sodium
5 leakage detection and reaction prevention. Because if
6 you have a failure of one of the heat pipes external
7 to the container, now you have the challenge of
8 consequential failure.
9 So, what's your position on -- this would
10 be the SFR sodium fast reactor, Design Criteria No. 73
11 on sodium leakage detection and prevention, and
12 reaction prevention and mitigation. Because it's not
13 just interaction with concrete that's of concern. I
14 would say that's probably of least concerns actually
15 here. It's the air-sodium interaction and the
16 potential additional heat and the loading on the heat
17 pipe itself, and the potential for consequential
18 failure.
19 So, how are you approaching 73 with regard
20 to air-sodium interactions?
21 MR. OBERSON: I guess it's a question, do
22 we believe that it applies to air interactions,
23 sodium-air interactions, or what might, I guess --
24 MEMBER KIRCHNER: Yes. I mean, because it
25 leads to a sodium fire. And traditionally, you know,
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1 for sodium fast reactors, there's been a guard vessel
2 around the sodium systems to prevent that kind of
3 interaction.
4 MR. OBERSON: Yes, I mean, my
5 understanding of PDC 73 -- and I guess this is a case
6 where I could appeal to even one of the Westinghouse
7 staffers to want to speak to it -- but the intent of
8 PDC 73 as it relates to sodium reaction and reaction
9 prevention mitigation would be addressed by -- the
10 sodium-air interactions would be addressed by that
11 PDC. Does Westinghouse want to speak to that?
12 MR. SMITH: Yes. This is Matt Smith from
13 Westinghouse.
14 I wanted to clarify that there is an
15 additional barrier, and we can get into the details of
16 that during the closed session. But there are two
17 barriers between sodium and air. So, that is a design
18 feature that we are considering here. I wanted to
19 make sure that was clear.
20 MEMBER KIRCHNER: Okay. No. Thank you.
21 I know that. I wanted you to say that for the public.
22 MR. SMITH: Yes, okay.
23 (Laughter.)
24 MR. OBERSON: Noted.
25 MEMBER HALNON: So, this is Greg. I have
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1 a quick question on some of the language, and you can
2 stay on this slide.
3 You talk about the PDC intent is met.
4 Back in a previous life, we used to use that language
5 to try to show compliance with a regulation because we
6 didn't like the words that were being used and
7 couldn't quite meet the words of the regulation.
8 So, when you say the PDC intent is met,
9 are you, basically, saying this very specific language
10 is equivalent to what the PDC requires or is there
11 something softer there?
12 MR. OBERSON: I mean, I guess I would say
13 that it's soft in the sense that the presumption is
14 the PDC is intended to provide assurance of, you know,
15 provide a level of assurance of safety, I suppose is
16 how I would say it, and that the same assurance is
17 provided by the wording of the specific eVinci PDC, in
18 this case, the eVinci PDC, as would be provided by the
19 sort of generically-written one, but with the change
20 necessary to sort of translate from one design to the
21 other. So, it's sort of a soft --
22 MEMBER HALNON: Okay.
23 MR. OBERSON: Yes, it's sort of a soft
24 intent.
25 MEMBER HALNON: So, we should not read
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1 into a generic aspect of this, but it's more of a
2 specific eVinci issue?
3 MR. OBERSON: Yes.
4 MEMBER HALNON: And then, are we going to
5 assume that was because of the underlying safety basis
6 words, that there's an equivalent level of assurance
7 of safety?
8 MR. OBERSON: Yes.
9 MEMBER HALNON: Okay. No, I just wanted
10 to get that cleared up. I wanted to make sure I
11 understood what you were meaning there. Because you
12 use it on several of these.
13 Thank you.
14 MR. OBERSON: Yes, I understand. Thank
15 you.
16 CHAIR ROBERTS: Okay. Any other questions
17 or comments from the members and consultants?
18 (No response.)
19 Hearing none, we're going to end the open
20 session.
21 So, anybody from the public who would like
22 to make a comment? Go ahead and unmute yourself;
23 identify your name and affiliation, if appropriate,
24 and then, state your comment.
25 (No response.)
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1 Okay. Hearing none, we are now going to
2 close the open session. Okay. So, we're going to
3 close the open session now and, at 2:15 p.m. Eastern,
4 we'll start the closed session.
5 (Whereupon, at 2:01 p.m. EDT, the open
6 session of the Subcommittee was concluded, to resume
7 at 2:15 p.m. EDT in closed session.)
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WAAP-13023, Revision 0, eVinci' Microreactor - Principal Design Criteria Topical Report ACRS Subcommittee Meeting - Open Session
Westinghouse Electric Company 51 Bridge Street Pittsburgh, PA 15223
© 2024 Westinghouse Electric Company LLC All Rights Reserved 11 eVinci Microreactor
Principal Design Criteria Topical Report ACRS Subcommittee Meeting - Open Session
August 21, 2024
eVinci is a trademark or registered trademark of Westinghouse Electric Company LLC, its affiliates and/or its subsidiaries in the United States of America and may be registered in other countries throughout the world. All rights reserved. Unauthorized use is strictly prohibited. Other names may be trademarks of their respective owners.
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Agenda 2
- eVinci Microreactor Design Overview
- eVinci Microreactor Deployment Model Overview
- eVinci Microreactor Nuclear Regulatory Commission (NRC) Pre-Application Engagement to Date
- Questions
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eVinci Microreactor Design 3 Safety through passive heat pipe technology, enabling a very low -pressure reactor
Heat Pipes Shielding &
Bulkhead Parameter eVinci MicroreactorControl Drums
Power 15 MWt Fuel Cycle 8 years Fuel (Enrichment) Tr i-structural Isotropic (TRISO) (19.75%)
Coolant Heat Pipes Reactor Pressure ~1 atm Moderator Graphite Power Conversion Open-Air Brayton Efficiency 34% PrimaryHeat Decay Heat Removal Radial Conduction Shutdown Rods Exchanger
Graphite Core Radial Reflector Block Steel Canister
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eVinci Microreactor Site Layout 4
Site and facility shown for single unit
- All buildings and systems: above ground
- Reactor site footprint: < 3 acres
- Building footprint: <0.5 acres
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eVinci Microreactor Deployment Model 5
eVinci Microreactor Deployment
1 2 3 4 5
Assemble in factory Transport to site Install and operate at site Test reactor for safety eVinci microreactor feature performance licensing approval demonstration Primary reactor
Test reactor - testing, data collection and analysis Replacement reactor 7 6
Refuel/refurbish Transport away from site Remote monitoring station
8
Fuel storage facility Limited site staff with remote or decommission Operated reactor monitoring
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Pre-Application Engagement - White Papers 6
Current Status:
- Topic Submittal # Topic Submittal # Topic Submittal Wave Wave Wave
1 Facility Level Design Submitted - 1 13 Advanced Logic Submitted - 3 25 Inservice Inspection Submitted - 5 Description Sys t e m(ALS) v2 Program/Inservice Testing Program 2 Principal Design Criteria Submitted - 1 14 Component Qualification Submitted-3 26 Post-Accident Monitoring System Submitted - 5
3 Safety and Accident Submitted - 1 15 Emergency Plan Zone Submitted - 3 27 Equipment Qualification Submitted - 5 Analysis Methodologies Sizing Methodology
4 Licensing Modernization Submitted - 1 16 Physical Security Submitted - 3 28 Probabilistic Risk Assessm ent and Submitted - 5 Project Implementation Transportation Risk Assessment 5 Regulatory Analysis Submitted - 2 17 Heat Pipe Design, Submitted - 3 29 Fire Protection Submitted - 5 Qualification, and Testing
6 Deployment Model Submitted - 2 18 Nuclear Design Submitted - 3 30 Cyber Security Submitted - 5 7 Safeguards Information Submitted - 2 19 U.S Transportation Strategy Submitted - 3 31 Radiation Protection and Submitted - 6 Plan Contamination Methodology 8 Test and Analysis Process Submitted - 2 20 Phenomena Identification Submitted - 4 and Ranking Table (PIRT) 9 Functional Containment Submitted - 2 21 Integral Effects and Submitted - 4 and Mechanistic Source Transient Testing Term 10 Composite Material Submitted - 2 22 Refueling and Submitted - 4 Qualification and Testing Decommissioning
11 Fuel Qualification and Submitted - 3 23 Seismic Methodology Submitted - 4 Testing 12 Code Qualification Submitted - 3 24 Operations and Remote Submitted - 4 Monitoring
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Topical Reports 7
- Report Title Submittal Date 1 ALS v2 Platform Submitted (Dec. 2022) 2 ALS v2 Development Process Submitted (Dec. 2022) 3 Principal Design Criteria Submitted (Jun. 2023) 4 ALS v2 Technical Specification Surveillance Requirement Elimination Submitted (Dec. 2023) 5 Nuclear Design Methodology Submitted (May 2024) 6 Westinghouse TRISO Fuel Design Methodology Submitted (Aug. 2024) 7 Composite Materials 8 Testing Program 9 Physical Security 10 Functional Containment and Mechanistic Source Term Methodology 11 Design Basis Analysis Methodology 12 Metallic Materials 13 Graphite Materials 14 Heat Pipe Qualification Criteria 15 Component Qualification Methodology 16 Inservice Inspection 17 Inservice Testing
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8
Principal Design Criteria Topical Report Overview
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Section 1.0 - Introduction 9
- NRC white paper feedback (ML22059A460) considered in topical report development
- Purpose
- eVinci microreactor PDC and the basis for their selection
- PDC include safety-related (SR) and nondesign criteria (DC)- safety-related with special treatment (NSRST)
- Derivation of eVinci microreactor PDC based on the following applicable regulationsand regulatory guidance:
- General Design Criteria (GDC) in Title 10 of the Code of Federal Regulations (CFR) Part50 Appendix A
- Incorporates the safety case for the eVinci microreactor developed based on NuclearEnergy Institute (NEI) 18-04 (endorsed by NRC in RG 1.233) and NEI 21-07 (endorsed by NRC in RG 1.253)
- Westinghouse requests NRC review and approval on the set of PDC for the eVincimicroreactor, including the list of and justification for the GDC identified as not applicable to the eVinci microreactor.
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Section 2.0 - Summary of the eVinci Microreactor 10 Design and Facility Description
See design summary provided in Slides 3-4
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Section 3.0 - PDC Development Summary 11
- PDC derived based on the design criteria in RG 1.232 and GDC in 10 CFR Part 50 Appendix A
- Each GDC and DC contained in RG 1.232 reviewed for applicability to design and were either kept as-is, edited, or determined to not be applicable in its entirety
- eVinci microreactor PDC are function-based and not structure, system, or component (SSC) specific; therefore, there is no differentiation between PDC-Required Functional Design Criteria (RFDC) and PDC-Complementary Design Criteria (CDC) as described in NEI 21-07
eVinci microreactor PDC crosswalk provided on Slide 13.
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Section 3.0 - PDC Development Summary 12
- NEI 18-04 (endorsed by RG 1.233) and NEI 21- 07 (endorsed by RG 1.253) were used to risk-inform the PDC and confirm PDC for the eVinci microreactor required safety functions (RSFs) were appropriately included
- Examples of ways PDC have been revised based on NEI 18- 04 and NEI 21- 07:
- Use of Quality Assurance PDC text from NEI 21- 07
- Allow for defense-in-depth process to drive need for multiple barriers
- Important to safety revised to safety significant
- Postulated accidents revised to licensing basis events or design basis accidents (as applicable)
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Section 3.0 - eVinci Microreactor PDC Crosswalk 13
10 CFR 50 Appendix A Applicable RG 1.232 eVinci Microreactor PDC Text 10 CFR 50 Appendix A Applicable RG 1.232 eVinci Microreactor PDC Text GDC Appendices Compared RG 1.232 PDCs GDC Appendices Compared to RG 1.232 PDCs 1 A Modified from RG 34 C Modified from RG 2 A Modified from RG 35 N/A N/A 3 A Modified from RG 36 N/A N/A 4 A Modified from RG 37 N/A N/A 5 A Modified from RG 38 N/A N/A N/A (PDC 6 newly defined) N/A Reactor-specific PDC 39 N/A N/A 10 C Modified from RG 40 N/A N/A 11 A Modified from RG 41 N/A N/A 12 A, C Modified from RG 42 N/A N/A 13 A Modified from RG 43 N/A N/A 14 C Identical to RG 44 N/A N/A 15 C Modified from RG 45 N/A N/A 16 C Modified from RG 46 N/A N/A 17 C Modified from RG 50 N/A N/A 18 N/A N/A 51 N/A N/A 19 A Modified from RG 52 N/A N/A 20 C Modified from RG 53 N/A N/A 21 N/A N/A 54 N/A N/A 22 A Modified from RG 55 N/A N/A 23 A Identical to RG 56 N/A N/A 24 A Identical to RG 57 N/A N/A 25 C Identical to RG 60 A Identical to RG 26 C Modified from RG 61 A Modified from RG 27 N/A N/A 62 A Modified from RG 28 A Modified from RG 63 A Modified from RG 29 A Identical to RG 64 A Modified from RG 30 N/A N/A N/A B (Criterion 71) Modified from RG 31 N/A N/A N/A B (Criterion 73) Modified from RG 32 N/A N/A N/A B (Criterion 74) Modified from RG 33 N/A N/A N/A B (Criterion 78) Modified from RG
Table 3.3-1 in Topical Report
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Section 4.0 - eVinci Microreactor PDC 14
Title:
Provides number and title of PDC. In most cases, the title is from 10 CFR Part 50 Appendix A and/or RG 1.232; however, in some cases the title has been changed to reflect specific aspects of the eVinci microreactor design.
- eVinci microreactor PDC: Provides eVinci microreactor PDC wording.
- Position: Provides determination of whether a given Advanced Reactor Design Criteria (ARDC), Sodium-Cooled Fast Reactor (SFR)-DC, or Modular High-Temperature Gas -Cooled Reactor (MHTGR) -DC from RG 1.232 (or other source, as applicable) is adopted with or without changes. Modifications made to the underlying design criteria are shown in red with a strikethrough for removed text and in blue with underline for added text. The source DC is provided adjacent to the modifications for convenience.
- Basis: Provides justification and rationale for why a certain design criteria (or portion of a certain design criteria) has been determined to be applicable to the eVinci microreactor design. Also describes and justifies changes in text to develop the eVinci microreactor PDC.
- Source: Provides the ARDC, SFR-DC, or MHTGR-DC from RG 1.232 (or other source, as applicable).
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Section 4.0 - Example PDC (Modified from ARDC) 15
Title:
- 1. Quality standards and records eVinci Safety significant structures, systems, and components shall be designed, fabricated, erected, and tested to qualit y standards comm ensurate with the safety significance of microreactor the functions to be performed. W here generally recognized codes and standards are used, they shall be identified and evaluated to determine their applicability, adequacy, and sufficiency and shall be supplemented or modified as necessary to assure a quality product in keeping with the safety significant function. A quality assurance program PDC: shall be established and implemented in order to provide reasonable assurance that these structures, systems, and components will satisfactorily perform their safety significant functions. Appropriate records of the design, fabrication, erection, and testing of safety significant structures, systems, andcomponents shall be maintained by or under thecontrol of thenuclear power unit licenseefor an appropriateperiodof time.
Position: PDC 1 for theeVinci microreactor designuses thelanguagein RG 1.232, ARDC 1 with changes to beconsistent with theQuality AssurancePDC text in NEI 21- 07, Section C, 5.3.1.
RG 1.232, Appendix A, Criterion 1 eVinci microreactor PDC 1 Structures, systems, and components important to safety shall be designed, Safety significant structures, systems, and com ponents important to safety shall be fabricated, erected, and tested to quality standards commensurate with thedesigned, fabricated, erected, and tested to quality standards commensurate with importance of the safety functions to be performed. W here generally recognized the importance safety significance of the safety functions to be performed. W here codes and standards are used, they shall be identified and evaluated to determine generally recognized codes and standards are used, they shall be identified and their applicability, adequacy, and sufficiency and shall be supplemented or modified evaluated to determine their applicability, adequacy, and sufficiency and shall be as necessary to assure a quality product in k eeping with the required safety supplemented or modified as necessary to assure a qualit y product in keeping with function. A quality assurance program shall be established and implemented in the required safety significant function. A qualit y assurance program shall be order to provide adequate assurance that these structures, systems, and established and implemented in order to provide adequate reasonable assurance components will satisfactorily perform their safety functions. Appropriate records of that these structures, systems, and components will satisfactorily perform their the design, fabrication, erection, and testing of structures, systems, and components safety significant functions. Appropriate records of the design, fabrication, erection, important to safety shall be maintained by or under the control of the nuclear power and testing of safety significant structures, s ys t e m s, and components important to unit licenseethroughout thelife of theunit. safety shall be maintained by or under the control of the nuclear power unit licensee throughout the life for anappropriate period of the unit time.
Basis: This requirement is applicable, because the eVinci microreactor contains safety significant SSCs that are designed, fabricated, erected, and tested to qualit y standards that correspond with theimportance of the safety functions that need to be performed. The eVinci microreactor will follow theW estinghouse Quality Management Sys t e m.
The phrase important to safety is changed to safety significant to align with the terminology in the proposed Quality Assurance PDC in NEI 21- 07, Section C, 5.3.1.
The phrase throughout the life of the unit was changed to for an appropriate period of tim e to account for the application of qualit y assurance special treatments to NSRST SSCs. Again, this aligns the PDC text with NEI 21- 07, Section C, 5.3.1.
Source: RG 1.232, Appendix A, Criterion 1 and NEI 21- 07, Section 5.3.1
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Section 4.0 - Example PDC (Newly Developed) 16
Title:
- 6. Monitoring, inspection, and testing eVinci Safety significant structures, systems, and com ponents shall be designed to permit monitoring, surveillance, periodic inspection, and/or testing as necessary to ensure microreactor functional capability commensurate with the safety significance of the functions to be performed. Functional testing shall ensure the operability and performance of the s ys t e m components, and the operability of the s ys t e m as a whole and, under conditions as close to design as practical, the performance of the full operational sequence PDC: that brings thesystem into operation, including associated systems, for licensing basis events.
Position: PDC 6 of the eVinci microreactor design uses the languagefrom RG 1.232, MHTGR-DCs 18, 21, 32, 36, 37, 39, 40, 45, and 46 into a single PDC for monitoring, inspection, and testing.
RG 1.232, Appendix C eVinci microreactor PDC 6 No generic monitoring, inspection, and testingPDC in RG 1.232. Safety significant structures, systems, and components shall be designed to permit monitoring, surveillance, periodic inspection, and/or testing as necessary to ensure functional capability commensurate with the safety significance of the functions to be performed. Functional testing shall ensure the operability and performance of the s ys t e m components, and the operability of the s ys t e m as a whole and, under conditions as close to design as practical, the performance of the full operational sequence that brings the system into operation, including associated systems, for licensing basis events.
Basis: Generic wording is used to support a single monitoring, testing, and inspection PDC, which replaces the need for RG 1.232, MHTGR-DCs 18, 21, 32, 36, 37, 39, 40, 45, and 46.
Monitoring, surveillance, periodic inspection, and/or testing will be established as special treatments in accordance with the NEI 18-04 integrated decision-making process (IDP) and will meet the performance intent of the eVinci microreactor. Accordingly, the eVinci microreactor inservice inspection and inservice testing programs will be developed to support inspection and testing needs that are identified through the NEI 18- 04 process.
Additionally, the Inspections, Tests, Analyses, And Acceptance Criteria (ITAAC), to be defined in the DCA will inform what is required in terms of testing and inspection prior to operation.
The phrase safety significant is used in this PDC to align with the risk -inform ed, perform ance-based (RIPB) term inology used in NEI 18- 04 and NEI 21- 07.
Source: RG 1.232, Appendix C, Criteria 18, 21, 32, 36, 37, 39, 40, 45, and 46
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Section 4.0 - Example PDC (Identical to RG 1.232) 17
Title:
- 14. Reactor helium pressure boundary eVinci The reactor helium pressure boundary shall be designed, fabricated, erected, and tested so as to have an extremely low probability of abnormal leakage, of rapidly microreactor propagating failure, of gross rupture, andof unacceptable ingress of moisture, air, secondary coolant, or other fluids.
PDC:
Position: PDC 14for theeVinci microreactor designuses the languagein RG 1.232, MHTGR-DC 14with no changes.
RG 1.232, Appendix C, Criterion 14 eVinci microreactor PDC 14 The reactor helium pressure boundary shall be designed, fabricated, erected, and The reactor helium pressure boundary shall be designed, fabricated, erected, and tested so as to have an extrem ely low probability of abnormal leakage, of rapidly tested so as to have an extrem ely low probability of abnormal leakage, of rapidly propagating failure, of gross rupture, and of unacceptable ingress of moisture, air, propagating failure, of gross rupture, and of unacceptable ingress of moisture, air, secondary coolant, or other fluids. secondary coolant, or other fluids.
Basis: This requirement is applicable because the eVinci microreactor has a helium environment in the reactor canister. This PDC addresses the need to consider leakage of contaminants into the helium in the reactor canister.
Source: RG 1.232, Appendix C, Criterion 14
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Section 4.0 - Example N/A GDC 18
Title:
- 27. Combined reactivity control systems capability GDC: The reactivity control systems shall be designed to have a combined capability, in conjunction with poison addition by the emergency core cooling system, 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.
Screening The objective of this requirement is satisfied by PDC 26 for reactivity control.
Rationale for GDC Being N/A:
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19
Questions
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2020
Thank Yo u
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NRC Staff Review of the Westinghouse Principal Design Criteria Topical Report for the eVinci Microreactor Design
Patrick Boyle, Project Manager Michelle Vega Rodriguez, Associate Project Manager Dan Beacon, Nuclear Engineer Office of Nuclear Reactor Regulation Division of Advanced Reactors and Non-Power Production and Utilization Facilities Agenda
- Review chronology
- Topical report (TR) purpose and review strategy
- Safety evaluation (SE) over view
- Conclusions
2 Review Chronology
- Aug. 15, 2023: TR accepted for review.
- Sept. 15 and Oct. 31, 2023: Clarification meetings held.
- Nov. 16, 2023: Requests for Additional Information (RAIs) issued.
- Edits to reflect the items discussed during the clarification meeting discussions and RAIs.
- July 26, 2024: NRC Staff s Draft Safety Evaluation Issued (ML24176A132)
3 TR Purpose and Review Strategy
- Purpose of TR:
- Provide PDCs to support both the design and licensing process and compliance with pertinent regulatory requirements of Title 10 of the Code of Federal Regulations (10 CFR) Parts 50 and 52 associated with PDCs.
- Review strategy
- Review conformance with Regulatory Guide (RG) 1.232
- Evaluate deviations from RG 1.232 in consideration of the key eVinci design features
- Consider applicability of RG 1.232 appendices and guidance to novel eVinci design features
4 Safety Evaluation Over view
- Regulations and guidance
- eVinci design features (informational)
- eVinci PDCs
- PDCs related to fuel storage
- PDCs with specific considerations
- Limitations and conditions
- Conclusions
5 Regulations
- In accordance with the provisions of 10 CFR Parts 50 and 52, applicants for a construction permit (CP), operating license (OL), standard design certification (DC), combined license (COL), standard design approval (SDA), or manufacturing license (ML) must submit PDCs for the proposed facility. Specifically,
- 10 CFR 50.34(a)(3)(i), which requires, in part, that applications for a CP include PDCs for the facilityAn OL would reference a CP, which would include PDCs..
- 10 CFR 52.47(a)(3)(i), which requires, in part, that applications for a standard DC include PDCs for the facility.
- 10 CFR 52.79(a)(4)(i), which requires, in part, that applications for a COL include PDCs for the facility.
- 10 CFR 52.137(a)(3)(i), which requires, in part, that applications for an SDA include PDCs for the facility.
- 10 CFR 52.157(a), which requires, in part, that applications for a ML include PDCs for the reactor to be manufactured.
- 10 CFR Part 50, Appendix A provides requirements on the scope and content of PDCs for non-light water reactors (non-LW R s ) :
- The principal design criteria establish the necessary design, fabrication, construction, testing, and performance requirements for structures, systems, and components important to safety; that is, structures, systems, and components that provide reasonable assurance that the facility can be operated without undue risk to the health and safety of the public.
6 Guidance
- RG 1.232, Guidance for Developing Principal Design Criteria for Non -L i ght Wate r Reactors (ML17325A611)
- Appendices provide example DCs
- RG 1.233, Guidance for a TBased Methodology to Inform the Licensing Basis and Content of Applications for echnology -Inclusive, Risk-Informed, and Performance-Licenses, Certifications, and Approvals for Non -L i ght Wate r Re a c tors (ML20091L698)
- Endorses NEI 18Non-Light Water Reactor Licensing Basis Development,- 04, Risk -Informed Performance-Based T Revision 1 (ML19241A472)echnology Inclusive Guidance for
- RG 1.253, Guidance for a TMethodology to Inform the Licensing Basis and Content of Applications for echnology -Inclusive Content of Application Licenses, Certifications, and Approvals for Non -L i ght-Water Reactors, (ML23269A222) was in draft form (DG-1404) at the time of submittal.
- Endorses NEI 21Analysis Report: For Applications Utilizing the NEI 18-04 Methodology- 07, Technology Inclusive Guidance for Non-Light Water Reactors - Safety, Revision 1 (ML22060A190).
7 eVinci Design Features
- High-temperature heat pipe reactor, 15MWth
- Horizontal hexagonal graphite blocks, thermal neutron spectrum
- Normal heat removal: Heat pipes to open-air Brayton cycle
- Decay heat removal: Conduction and radiation to environment (passive)
- Reactivity control: Drums, shutdown rods, and inherent feedback
- Functional containment (TRISO layers, Reactor Canister)
- No active electrical power to perform required safety functions
- Transportable
8 eVinci PDC Over view
- Sodium is contained in the heat pipes as the working fluid
- Design similarities: fuel, core, vessel, functional containment and materials
- New PDC 6 proposed
- Combines multiple monitoring, inspection, and testing related DCs
9 PDCs effectively identical to RG 1.232 DCs
- Applicable PDCs: 10, 11, 14, 15, 23, 24, 25, 28, 29, and 60
- The above eVinci PDCs were found acceptable on the bases that:
- Differences in language or terminology, if any, did not change intent of PDC.
- Ex: PDC 11, Changing systems to structures, systems and components.
- The underlying safety basis of RG 1.232 remains applicable for each, as applied to the eVinci design.
10 PDCs influenced by LMP terminology
- Applicable PDCs: 1, 2, 3, 4, 5, 16, 20, and 22
- The above eVinci PDCs use similar language as RG 1.232 DCs, with key terminology changes to reflect planned LMP implementation.
- Replace important to safety and postulated accident from RG 1.232 DC with safety -significant and licensing basis event to align with language from NEI 18-04 (and NEI 21-07).
- Underlying safety basis remains applicable to the eVinci design.
11 PDCs influenced by the LMP approach
- Applicable PDCs: 6, 17, 26, 34, and 78
- RG 1.253 was in draft (DG-1404), so refinement of the PDCs into RFDCs + CDCs was not implemented in this topical report.
- The NEI 18-04 approach includes an evaluation of defense-in-depth adequacy intended to address concerns related to independence, redundancy, diversity, and defense-in-depth.
- Only acceptable if used with LMP licensing approach
- Limitation/Condition 2
12 PDCs related to storage
- eVinci PDCs 61, 62, and 63 modify RG 1.232 DC language to reflect reactor fuel handling and storage plans for the eVinci design.
- Replace concepts of fuel storage,the concept of reactor storage to reflect the fueled -reactor unit deployment waste, and associated handling with and handling approach being sought for implementation.
- Tstorage were under Commission consideration at the time of reviewechnical and regulatory aspects of fueled-reactor handling and.
- Condition/Limitation 3: Only acceptable ifsubmittal, fueled-reactor storage is found to conform with, in a future licensing Commission policy
13 PDC 12 - Suppression of Power Oscillations
- Reflects broader applicability of SSCs than ARDC -12.
- Reactor core, associated structures, and associated coolant, control, and protection syste m s
- Reflects the use of SARRDLs, consistent with MHTGR-DC 12, rather than SAFDLs.
- Similarity in fuel design and radionuclide retention approach
- Found appropriately applicable to the eVinci design and that RG 1.232 safety basis is maintained.
14 PDC 17 - Electric power systems
- Incorporates LMP terminology changes: safety significant, required safety function, and design basis accidents.
- [Discussion deferred to closed session]
- Electrical power for RSFs (if needed) is covered by the PDC, regardless.
15 PDC 19 - Microreactor control
- Adapts ARDC 19 language [Discussion deferred to closed session]
- PDC accepted with Limitation/Condition 4:
- [Discussion deferred to closed session]
16 PDC 64 - Monitoring Radioactive Releases
- Changes to RG language reflect functional containment approach and LMP terminology.
- TR Rev. 0 included additional specificity with undefined terminology.
- Public meeting held for discussion between NRC and Westinghouse
17 PDC 71 - Cover gas purity control
- Applicability to helium cover gas purity in the eVinci reactor canister.
- Removed SFR-DC 71 language that referred to sodium primary coolant.
- eVinci PDC 73 pertains to detection of sodium leakage and/or reactions from hermetically sealed heat pipes.
- PDC intent of maintaining primary cover gas purity and underlying safety basis aligns with RG 1.232 and remains applicable in the context of the eVinci design.
18 PDC 73 - Sodium leakage detection and reaction prevention and mitigation
- The SFR-DC 73 language is expanded with a requirement to ensure passive heat removal system availability.
- Language regarding sodium-concrete interactions is removed.
- Multiple non-concrete barriers exist between the sodium contained in heat pipes and any concrete structures outside the reactor canister or primary heat exchanger.
- PDC intent and underlying safety basis aligns with RG 1.232 and remains applicable in the context of the eVinci design.
19 PDC 74 - Sodium/water reaction prevention/mitigation
- Language regarding steam-water energy conversion systems is removed because eVinci relies on an open-air Brayton conversion system.
- PDC intent and underlying safety basis aligns with RG 1.232 and remains applicable in the context of the eVinci design.
20 PDC 78 - Sodium heat pipe interfaces
- Changes reflect that sodium is only contained in heat pipes, and not as a primary coolant.
- Language associated with redundancy is removed to reflect the use of LMP and the associated DiD adequacy assessment.
- PDC intent and underlying safety basis aligns with RG 1.232 and remains applicable in the context of the eVinci design.
21 Safety Evaluation Over view
- Regulations and guidance
- eVinci design features (informational)
- eVinci PDCs
- PD C s re l ate d to stora ge
- PDCs with specific considerations
- Limitations and conditions
- Conclusions
22 PDCs related to monitoring, inspection and testing
- RG 1.232 DCs 18, 21, 32, 36, 37, 39, 40, 45, and 46 pertain to monitoring, inspecting, and testing of various specific SSCs.
- Similar language used in each.
- Effectively mirrors the language of the replaced criteria.
- Applicability encompasses all replaced criteria.
23 Heat transport functions, Reactor coolant system boundar y - DCs 30, 31, and 33
- DCs 30, 31, and 33 are not directly applicable to the unique heat removal design of the eVinci reactor (heat pipes).
- The DCs refer to a reactor coolant system, but the eVinci design does not include any forced convection or primary coolant as meant in RG 1.232.
- Review approach: Ensure the fundamental safety concepts intended by DCs 30, 31, and 33 are addressed by PDCs.
- Concepts: Reactor coolant system (reactor canister/HPB, in the eVinci context) integrity, retainment of radioactive materials, appropriate heat removal, and monitoring /prevention of air, moisture, or other fluid ingress.
24 Heat removal and emergency cooling - DCs 35, 38, and 44
- DCs 35, 38, and 44 objectives focus on adequate heat removal capability to cool the core, containment, and associated SSCs.
25 Functional Containment - DCs 41, 42, 43, and 50- 57
- DCs 41, 41, 43, and 50-57
[Discussion deferred to closed session]
26 Limitations and Conditions (L&Cs)
- 1. Westinghouse is requesting approval for the proposed PDCs based on a preliminary design and plans to incorporate the NEI 18-04 and NEI 21-07 processes (subsequently referred to as the licensing modernization project (LMP) in its licensing approach). The eVinci TM design changes and associated LMP implementation could necessitate a revision to the proposed PDCs described in the TR. Therefore, future licensing applicants referencing the TR must confirm that the PDCs in this TR remain appropriate for its design. If additional or revised PDCs are identified that are not within the scope of what is approved in this TR, those PDCs will be subject to further NRC staff review.
- 2. The eVinciTM PDCs 6, 17, 26, 34, and 78 include language that reflects the implementation of the LMP. Specifically, departures from NRC endorsed PDC development guidance are made, including the removal or replacement of language regarding defense-in-depth, redundancy, independence, and/or diversity. The NRC staff finds the proposed language of these PDCs acceptable based on the assumption that the LMP process will be implemented during licensing and will address the topics of defense-in-depth, redundancy, independence, and/or diversity. As such, the NRC staff finds eVinciTM PDCs 6, 17, 26, 34, and 78 acceptable only when referenced to support the licensing of a design or facility that also includes the implementation of the LMP in its licensing approach.
27 Limitations and Conditions (L&Cs)
- 3. The NRC staff acknowledge that PDCs 61, 62 and 63 are developed to support eventual implementation of a fueled microreactor unit deployment strategy. The NRC staff finds the PDCs acceptable on the condition that such an approach will be deemed acceptable in a future licensing action. The NRC staff makes no determination in this SE regarding the acceptability of transporting, manipulating, and/or storing a fueled microreactor unit. Such a determination would be subject to future licensing actions and subject to the requirements deemed applicable to those actions.
- 4. [Discussion deferred to closed session]
28 Conclusions
- Westinghouse considered each of the design aspects presented in RG 1.232.
- Westinghouse provided a sufficient set of PDCs for the eVincisubject to the L&Cs. design,
- The PDCs (subject to the L&Cs) establish the necessary design, fabrication, construction, testing, and performance DC for safety significant SSCs to provide reasonable assurance that the eVinci reactor could be operated without undue risk to the health and safety of the public.
- The TR is suitable for referencing in future licensing applications for the eVinci reactor.
29 Abbreviations
ARDC - Advanced reactor design criteria LW R - Light water reactor SFR - Sodium fast reactor CDC - Complimentary design criteria M H TG R - Modular high temperature gas SSC - Structure, system, or component CFR - Code of Federal Regulations reacto r SE - Safety evaluation CP - Construction permit NEI - Nuclear Energy Institute TR - Topical report DA N U - Division of Advanced Reactors and NRC - Nuclear Regulatory Commission TRISO - Tr i-structural Isotropic Non-Power Production and Utilization Facilities NRR - Office of Nuclear Reactor Regulation WEC - Westinghouse Electric Company DBA - Design basis accident PDC - Principal design criterion DC - Design criterion RAI - Request for additional information DG - Draft Guide RFDC - Required functional design criteria DiD - Defense in depth RG - Regulatory guide GDC - General design criterion RSF - Required safety function HALEU - High-assay low-enriched uranium SAFDL - Specified acceptable fuel design limit L&C - Limitation and/or condition SARRDL - Specified acceptable system LMP - Licensing Modernization Project radionuclide release design limit
30