ML25156A009
| ML25156A009 | |
| Person / Time | |
|---|---|
| Issue date: | 05/21/2025 |
| From: | Advisory Committee on Reactor Safeguards |
| To: | |
| References | |
| NRC-0356 | |
| Download: ML25156A009 (1) | |
Text
Official Transcript of Proceedings NUCLEAR REGULATORY COMMISSION
Title:
Advisory Committee on Reactor Safeguards Regulatory Rulemaking, Policies and Practices Subcommittee Docket Number:
(n/a)
Location:
teleconference Date:
Wednesday, May 21, 2025 Work Order No.:
NRC-0356 Pages 1-111 NEAL R. GROSS AND CO., INC.
Court Reporters and Transcribers 1716 14th Street, N.W.
Washington, D.C. 20009 (202) 234-4433
NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.
(202) 234-4433 WASHINGTON, D.C. 20005-3701 www.nealrgross.com 1
1 2
3 DISCLAIMER 4
5 6
UNITED STATES NUCLEAR REGULATORY COMMISSIONS 7
ADVISORY COMMITTEE ON REACTOR SAFEGUARDS 8
9 10 The contents of this transcript of the 11 proceeding of the United States Nuclear Regulatory 12 Commission Advisory Committee on Reactor Safeguards, 13 as reported herein, is a record of the discussions 14 recorded at the meeting.
15 16 This transcript has not been reviewed, 17 corrected, and edited, and it may contain 18 inaccuracies.
19 20 21 22 23
1 UNITED STATES OF AMERICA 1
NUCLEAR REGULATORY COMMISSION 2
+ + + + +
3 ADVISORY COMMITTEE ON REACTOR SAFEGUARDS 4
(ACRS) 5
+ + + + +
6 REGULATORY RULEMAKING, POLICIES AND PRACTICES 7
SUBCOMMITTEE 8
+ + + + +
9 WEDNESDAY, MAY 21, 2025 10
+ + + + +
11 The subcommittee met via Video 12 Teleconference, at 8:30 a.m. EDT, Vicki Bier, Chair, 13 presiding.
14 COMMITTEE MEMBERS:
15 VICKI M. BIER, Chair 16 DAVID A. PETTI, Member-at-Large 17 RONALD G. BALLINGER 18 VESNA B. DIMITRIJEVIC 19 CRAIG D. HARRINGTON 20 WALTER L. KIRCHNER 21 ROBERT P. MARTIN 22 SCOTT P. PALMTAG 23 THOMAS E. ROBERTS 24 MATTHEW W. SUNSERI 25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1716 14th STREET, N.W., SUITE 200 (202) 234-4433 WASHINGTON, D.C. 20009-4309 www.nealrgross.com
2 ACRS CONSULTANT:
1 DENNIS BLEY 2
3 DESIGNATED FEDERAL OFFICIAL:
6 ALSO PRESENT:
7 STEVEN ALFERINK, NRR/DRA 8
INDIA BANKS, NRR/DNRL 9
BOB BUDNITZ 10 JON FACEMIRE, NEI 11 ALISSA NEUHAUSEN, NRR/DRA 12 HANH PHAN, NRR/DANU 13 STACEY ROSENBERG, NRR/DRA 14 SHILP VASAVADA, NRR/DRA 15 16 17 18 19 20 21 22 23 24 25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1716 14th STREET, N.W., SUITE 200 (202) 234-4433 WASHINGTON, D.C. 20009-4309 www.nealrgross.com
3 CONTENTS 1
Opening Remarks.................
4 2
Discussion of Risk Assessment Information in 3
Light-Water Power Reactor Construction 4
Permit Applications Interim Staff Guidance 8
5 Public Comments on Proposed Interim 6
Staff Guidance
................. 93 7
Member Discussion................ 98 8
Adjourn 9
10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1716 14th STREET, N.W., SUITE 200 (202) 234-4433 WASHINGTON, D.C. 20009-4309 www.nealrgross.com
4 P-R-O-C-E-E-D-I-N-G-S 1
(8:30 a.m.)
2 CHAIR BIER: Call to order this meeting of 3
the Regulatory Rulemaking, Policies and Practices 4
Subcommittee of the Advisory Committee on Reactor 5
Safeguards.
6 I am Vicki Bier, the Chair of today's 7
subcommittee meeting.
8 Can people hear me okay online? Anybody 9
want to respond quickly?
10 PARTICIPANT: Yeah, we're fine, thanks.
11 CHAIR BIER: Okay, thank you.
12 All right. ACRS members in attendance in 13 person are Robert Martin, Tom Roberts, and myself.
14 ACRS members in attendance virtually via 15 Teams are Vesna Dimitrijevic, Craig Harrington, Walt 16 Kirchner, Scott Palmtag, Dave Petti, and Matt Sunseri.
17 We also have one of our consultants 18 participating virtually via Teams, Dennis Bley.
19 If I have missed anyone, either ACRS 20 members or consultants, please speak up now.
21 None. Michael Snodderly of the ACRS staff 22 is the Designated Federal Officer for the meeting.
23 No member conflicts of interest were 24 identified for today's meeting. And we do have a 25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1716 14th STREET, N.W., SUITE 200 (202) 234-4433 WASHINGTON, D.C. 20009-4309 www.nealrgross.com
5 quorum.
1 During today's meeting the subcommittee 2
will receive a briefing on the staff's Draft Final 3
Interim Staff Guidance on Content of Risk Assessment 4
and Severe Accident Information in Light-Water Power 5
Reactor Construction Permit Applications.
6 The staff has developed this guidance at 7
the request of several external stakeholders engaging 8
in the pre-application process. Key is the two-step 9
licensing process, 10 CFR Part 50. This process 10 involves issuance of a construction permit based on 11 design information documented in a preliminary safety 12 analysis report, or PSAR.
13 This interim staff guidance clarifies the 14 scope and depth of the staff review of the description 15 of risk assessment and severe accident information in 16 the PSAR for a light-water power reactor construction 17 permit application that uses risk assessment and 18 severe accident information in support of the 19 application.
20 The ACRS was established by statute and is 21 governed by the Federal Advisory Committee Act, or 22 FACA. The NRC implements FACA in accordance with our 23 regulations.
Per these regulations and the 24 committee's bylaws, the ACRS speaks only through its 25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1716 14th STREET, N.W., SUITE 200 (202) 234-4433 WASHINGTON, D.C. 20009-4309 www.nealrgross.com
6 published letter reports. Any member comments and 1
questions should be regarded as only the individual 2
opinions of that member, not a committee decision.
3 All relevant information related to ACRS 4
activities such as letters, rules for meeting 5
participation, and transcripts are located on the NRC 6
public website and can be easily found by typing 7
"about us ACRS in the search field on NRC's 8
homepage.
9 The ACRS, consistent with the agency value 10 of public transparency and regulation of nuclear 11 facilities provides opportunity for public comment 12 during our proceedings. We have received a request 13 from Jon Facemire with the Nuclear Energy Institute to 14 make a presentation to the committee on today's topic.
15 We have received no other written 16 statements or requests to make an oral statement from 17 the public but we have set aside time at the end of 18 this meeting for public comments, if there are any.
19 The ACRS will gather information, analyze 20 relevant issues and facts, and formulate proposed 21 conclusions and recommendations, as appropriate, for 22 deliberation by the full committee.
23 A transcript of the meeting is being kept 24 and will be posted on our website.
25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1716 14th STREET, N.W., SUITE 200 (202) 234-4433 WASHINGTON, D.C. 20009-4309 www.nealrgross.com
7 When addressing the subcommittee, 1
participants should first identify themselves and 2
speak with sufficient clarity and volume that they may 3
be readily heard. If you are not speaking, please 4
mute your computer on Teams, or by pressing star-6 if 5
you're on the phone.
6 Please do not use the Teams chat feature 7
to conduct sidebar discussions related to the 8
presentations. Rather, limit use of the meeting chat 9
function to report any IT problems.
10 For everyone in the room, please put all 11 your electronic devices in the silent mode and mute 12 your laptop microphone and speakers. In addition, 13 please keep sidebar discussions in the room to a 14 minimum since the ceiling microphones are live.
15 For the presenters, your table microphones 16 are unidirectional and you'll need to speak directly 17 into the front of the microphone to be heard today.
18 Finally, if you have any feedback to the 19 ACRS about today's meeting, we encourage you to fill 20 out the public meeting feedback form on the NRC's 21 website.
22 We will now proceed with the meeting. I 23 gather that Steve Alferink from the Division of Risk 24 Assessment at NRR is making an opening statement.
25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1716 14th STREET, N.W., SUITE 200 (202) 234-4433 WASHINGTON, D.C. 20009-4309 www.nealrgross.com
8 Is that correct?
1 MR. ALFERINK: Yes, that is correct.
2 CHAIR BIER: Okay, thank you, Steve. You 3
can go ahead.
4 MR. ALFERINK: Thank you.
5 Good morning and thank you for the 6
opportunity to discuss the Draft Interim Staff 7
Guidance for ISG on the Content of Risk Assessment and 8
Severe Accident Information in Light-Water Power 9
Reactor Construction Permit Applications.
10 My name is Steven Alferink and I am the 11 Acting Branch Chief at PRA Licensing Branch C in the 12 Division of Risk Assessment in the Office of Nuclear 13 Reactor Regulation.
14 In my opening remarks I want to take the 15 opportunity to highlight the background of this ISG.
16 In 2023 we initiated an effort to 17 determine the information content for PRA in severe 18 accidents in a preliminary safety analysis report for 19 a light-water power reactor construction permit 20 application. We received great support and engagement 21 from external stakeholders for this effort when we 22 first started thinking about developing this guidance 23 when some of our stakeholders stated a preference for 24 using 10 CFR Part 50.
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9 Since it has been almost 40 years since 1
the NRC received the last construction permit 2
application for a light-water power reactor much has 3
changed.
4 In this 40 years the NRC issued many 5
documents related to PRA and severe accidents, 6
including the Three Mile Island Action Plan in 1980, 7
which called for system reliability analyses that met 8
the 10 CFR 50.34 aspect, which required utilities with 9
any construction permit applications to establish 10 programs for reliability analysis.
11 The NRC later issued generic Letter 8820 12 which called for a systematic examination to identify 13 any plant-specific vulnerabilities for severe 14 accidents, the ITE, and a Supplement 4 which called 15 for individual plant examination of external events.
16 The Commission also issued its Policy 17 Statement on Severe Accidents in 1985, and its Policy 18 Statement on PRA Methods in 1995.
19 We recognize that policy statements are 20 not regulations. While they are not regulations, they 21 do provide the Commission's expectations, and we use 22 them to guide our efforts.
23 We first documented our efforts in a white 24 paper which we used to inform the development of this 25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1716 14th STREET, N.W., SUITE 200 (202) 234-4433 WASHINGTON, D.C. 20009-4309 www.nealrgross.com
10 Draft ISG. The development of the white paper and 1
subsequent Draft ISG was a team effort with 2
participation from three different divisions: the 3
Division of Risk Assessment, the Division of Advanced 4
Reactors and Non-Power Production and Utilization 5
Facilities, and the Division of New and Renewed 6
Licenses.
7 The team worked collaboratively for 8
several months, meeting weekly to review progress and 9
comment on the technical content. Consequently, we 10 believe this ISG content will fill a gap that exists 11 in regulatory guidance and will ensure efficient and 12 effective reviews of construction permit applications 13 for light-water power reactors.
14 The Project Manager for the ISG, India 15 Banks, will start the presentation.
16 Stacey Rosenberg, a Senior Reliability and 17 Risk Analyst in my branch, will provide the overview 18 of the background and content of the ISG.
19 Alissa Neuhausen, previously a Reliability 20 and Risk Analyst in my branch, and now the Acting 21 Branch Chief of the License Renewal Project Branch in 22 the Division of New and Renewed Licenses will provide 23 the summary of stakeholder comments and how we 24 disposition the public comments we receive.
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11 We look forward to today's discussion and 1
your feedback.
2 Thank you. And I will now turn it over to 3
India to start the presentation.
4 MS. BANKS: Thank you, Steven.
5 Good morning, ACRS Regulatory Rulemaking, 6
and Policies and Practices Subcommittee members.
7 My name is India Banks, Project Manager in 8
the Division of New and Renewed Licenses. Before 9
turning it over to Stacey and Alissa I want to thank 10 the ACRS Subcommittee for allowing the staff the 11 opportunity to meet with you today to discuss the 12 Interim Staff Guidance Content of Risk Assessment and 13 Severe Accident Information in Light-Water Power 14 Reactor Construction Permit Applications.
15 As Steven said, the technology of risk 16 assessment and severe accident analysis has advanced 17 significantly since the last power reactor 18 construction permit was issued in the 1970s.
19 Licensees and the NRC staff use risk 20 assessment techniques more effectively than ever 21 before. The staff has developed this ISG to clarify 22 the scope and depth of the staff review of the 23 description of risk assessment and severe accident 24 information in the PSAR for light-water power reactor 25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1716 14th STREET, N.W., SUITE 200 (202) 234-4433 WASHINGTON, D.C. 20009-4309 www.nealrgross.com
12 construction permit applications that uses risk 1
assessment and severe accident information to support 2
the application.
3 I want to commend the supporting staff in 4
DRA and the Division of Advanced Non-Power Production 5
and Utilization Facilities who helped develop this 6
guidance. The staff engaged with stakeholders in 7
several public meetings so the staff could consider 8
stakeholder views informing the need for positions 9
presented in this ISG.
10 On January 16th of 2025 the staff issued 11 a Notice for Public Comment on the Draft ISG. At the 12 end of the public comment period the staff received 13 comments from the Nuclear Energy Institute on nuclear 14 power. The staff addressed each comment and made 15 changes to the ISG accordingly.
16 During the presentation the staff will 17 discuss how these comments were addressed. The Staff 18 Guidance is addressed to the ACRS, and we look forward 19 to obtaining recommendations related to the issuance 20 of this ISG.
21 I will now turn it over to Stacey and 22 Alissa. Thank you.
23 MS. ROSENBERG: Thank you, India.
24 Can everybody hear me?
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13 (Simultaneous speaking.)
1 MS. ROSENBERG: I also want to thank the 2
ACRS Subcommittee for having us here this morning to 3
brief on the ISG. And since we have the introduction 4
slide up, I do want to take a second just to 5
acknowledge and thank those that were part of this 6
team:
7 Malcolm Patterson, who is here in the 8
room.
9 Keith Tetter I think is on the, on the 10 phone.
11 Marie Pohida who is out this week.
12 Mike Swim.
13 Steve Alferink who you just heard from.
14 Marty
- Stutzke, Jeff
- Wood, Anders 15 Gilbertson, who I know is also on the line, and Hanh 16 Phan.
17 So, thank you very much for your very hard 18 work on this.
19 And, oh, and Alissa Neuhausen and I were 20 co-authors of this project.
21 So, do you want to go to the next slide.
22 Okay. So, we're going to just, we're just 23 going to skip over the need for the effort.
24 MS. NEUHAUSEN: Yes.
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14 MS. ROSENBERG: Okay, yes.
1 So, we'll skip over the need for the 2
effort because Steve already went over that.
3 All right. So, we'll just jump into the 4
overview.
5 Okay. The ISG clarifies the scope and 6
depth of the staff review of the description of risk 7
assessment and severe accident information in the 8
Preliminary Safety Analysis Report, which I'll 9
probably refer to as PSAR for short.
10 In November of 2024 the Commission issued 11 Staff Requirement SECY-22-0052 titled "The Proposed 12 Rule on Alignment of Licensing Processes and Lessons 13 Learned from New Reactor Licensing. While the SRM 14 states the proposed rule does require operating 15 license applicants to submit a description of the 16 plant-specific PRA and its results, the SRM did not 17 require construction permit applicants to include this 18 information.
19 So, that's, that's an important piece of 20 information.
21 Nevertheless, some designers of new light-22 water reactors are using risk assessment to support 23 design decisions.
24 Next slide.
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15 So, the objectives of this guidance.
1 One of the most important points we want 2
to leave you with today is that the scope and level of 3
detail of risk information in the PSAR should 4
correspond to the design readiness at the time the 5
construction permit application is submitted, and how 6
the risk information is being used to support and 7
inform the construction permit applicant.
8 The intent is also to facilitate 9
consistency in the content of the CPAs, which would 10 lead to greater predictability of staff reviews.
11 The staff also wanted to clarify any 12 misconceptions that the PRAs for construction permit 13 applications must meet endorsed PRA standards.
14 MEMBER MARTIN: I'll jump in and ask a 15 question. I'm Bob Martin.
16 So, it's obviously, as you
- said, 17 addressing a gap with regard to the role of PRA and 18 CPAs. However, environmental reports always relied on 19
-- not always but for some time how have included PRA, 20 if not, you know, directly, implicitly in order to 21 address type exercises, cost-benefit analyses.
22 Are the objectives here to at least make 23 sure there's some consistency between how those PRAs 24 are informed or are there -- is it intentional to be 25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1716 14th STREET, N.W., SUITE 200 (202) 234-4433 WASHINGTON, D.C. 20009-4309 www.nealrgross.com
16 different? Are there different objectives to the two 1
PRAs?
2 I would imagine you would want to leverage 3
one piece of work or, you know, both the ER and PSAR.
4 MS. ROSENBERG: I, I would think that 5
that's, I would think that that would be an efficient 6
way to handle a situation. You know, I'm not --
7 MEMBER MARTIN: But?
8 MS. ROSENBERG: -- a utility.
9 I think that, you know, I don't know what 10 their requirements are.
11 You know, when, when you're doing a PRA 12 it's tailored to what you're looking for. So --
13 MEMBER MARTIN:
For the question 14 completeness would be, would apply to both; right?
15 Particularly in the space where you're looking at, you 16 know, severe accident mitigation, alternatives, such 17 like, you know, that sort of thing, because it all 18 goes back to what is the sign.
19 And, of course, you know, the PRA feeding 20 an ER is, you know, just like for a PSAR, can't be so 21 complete. I know this is all Part 51 stuff but it's 22 kind of, you know, a little bit of a duplication.
23 And going to the heart of the question, 24 was there any coordination with people that are 25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1716 14th STREET, N.W., SUITE 200 (202) 234-4433 WASHINGTON, D.C. 20009-4309 www.nealrgross.com
17 responsible for Part 51 and that, you know, the 1
environmental work and what goes into those reports 2
from a technical standpoint? And I can already tell.
3 MS. ROSENBERG: No, we haven't done this 4
review in coordination with the environmental reviews.
5 MEMBER MARTIN: Yeah, and it kind of in 6
interests of -- kind of got this ISG, you know, it was 7
preventing, you know, preventing unnecessary burden.
8 There might be value in knocking on a few doors and 9
getting, getting their feedback, you know, in another, 10 you know, another team within the agency that also is 11 interested.
12 MS. ROSENBERG: Yeah. Yeah, it's a good 13 point.
14 Shilp, did you have anything you wanted to 15 add?
16 MR. VASAVADA: Yeah.
17 So, they should start out on the NRC 18 provisional risk assessment. Quick question. Our 19 experience has been that the PRAs or the risk 20 assessments that are used to support the safety piece 21 of the application are then essentially leveraged for 22 the amount of use. They test no outcomes. The 23 bifurcation, the -- the underlying cause of the PRAs 24 that are used.
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18 They are essentially built 1
environmental reviews are same as applicable in risk 2
assessments as far as the safety piece.
3 You know, the comment is valid. Just we 4
need to make sure that we're not missing information 5
that we will need. However, my personal opinion is 6
what we have over here bridging the gap we'll 7
definitely address because the gap will still remain 8
because they are building it based on the safety 9
risks.
10 MS. ROSENBERG: Thank you.
11 Okay, so, I think --
12 MEMBER PETTI: This is, this is Dave. I 13 raised my hand but maybe people didn't see it. Dave 14 Petti.
15 I just had a question on the design 16 readiness issue.
17 Is this kind of a little chicken and egg?
18 Is the need for the PRA and the depth of the PRA 19 driving the design readiness in some sense or is it 20 the other way around, the design is where it is and so 21 the PRA is just, you know, where it is?
22 As I read the ISG, I kept thinking this 23 was going to pull the design to a further degree of 24 completeness, for better or worse, just because some 25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1716 14th STREET, N.W., SUITE 200 (202) 234-4433 WASHINGTON, D.C. 20009-4309 www.nealrgross.com
19 of the information that you'd like to see, even at the 1
CP stage, you know, require a lot of details. Did you 2
guys think about that at all?
3 MS. ROSENBERG: So, which comes first?
4 MEMBER PETTI: Do you think that the PRA is 5
going to drive the design to be more complete at the 6
CP stage than were you not to have the PRA?
7 MS. ROSENBERG: Yeah, I, yes, I think that 8
it could do that, absolutely. That could even be a 9
goal of an applicant to have that happen.
10 So, if that's, that could be their goal 11 going in. And even if it weren't, I think they would 12 get a lot of insight, helpful insight.
13 MEMBER PETTI: Certainly from the design 14 perspective, I agree, there's a lot of value in the 15 PRA really. But there's a lot of other stuff there 16 that looks like it will push them to have a graded, or 17 just simplified, just not complete of their design to 18 be able to, you know, to put together the PRA.
19 MS. ROSENBERG: Well, and that's why we 20 keep saying it depends on the design readiness and 21 what is being requested at the time.
22 So, it's very dependent. It's going to be 23 variable. You know, it depends how far along you are 24 on your design, an applicant is on their design and 25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1716 14th STREET, N.W., SUITE 200 (202) 234-4433 WASHINGTON, D.C. 20009-4309 www.nealrgross.com
20 what they're hoping, which regulatory finding they're 1
hoping to receive.
2 MR. VASAVADA: May I?
3 MS. ROSENBERG: Yes.
4 MR. VASAVADA: From the staff, member 5
Petti, I think what you are saying, as Stacey said, 6
something we struggled with a lot when we were 7
developing the ISG, because being a design expert I 8
would expect that there will be iterative process 9
continuously happening on the design side as to where 10 to draw the line, how much is enough on CP, et cetera.
11 And we tried to add as much as clarity as 12 to predictability, we did recognize that we had broad 13 spectrum in terms of the design readiness, as Stacey 14 said, part of the objectives, as well as what the risk 15 information is being used for.
16 And the ISG tries to cover that gap. If 17 there are aspects that are not available at the time 18 of the review, we recognize that. The ISG is the 19 guidance to the staff, recognizing that the majority 20 may be different and if there is not enough 21 information and there's a basis for that, that is 22 something that the staff can take a look at in its 23 review.
24 So, yeah, it's something that we struggled 25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1716 14th STREET, N.W., SUITE 200 (202) 234-4433 WASHINGTON, D.C. 20009-4309 www.nealrgross.com
21 with. And we think it's an iterative process that we 1
would not be able to, I would say, control. This ISG 2
I don't think is driving that either.
3 MEMBER PETTI: Because they don't have to 4
submit the PRA at the CP stage, correct?
5 MR. VASAVADA: Correct.
6 MEMBER PETTI: Okay. Until only at the OL 7
stage would you need to pull. So, there is some 8
flexibility then.
9 MR. VASAVADA: Right. And we recognize 10 that.
11 MEMBER PETTI: Yeah. Right. This is only 12 in the event that they do provide some guidance for 13 that. Okay.
14 MR. VASAVADA: This is where an applicant 15 chooses to use risk assessment information to support 16 their application.
17 MEMBER PETTI: Okay, thanks.
18 CHAIR BIER: Walt, if you want to go ahead.
19 MR. KIRCHNER: Thank you, Vicki.
20 Good morning. This is Walt Kirchner.
21 I'm looking at this last bullet and I'm 22 wondering if it means what it says, or you intend it 23 to mean what it says. Certainly you want people who 24 voluntarily use PRA, as Dave was saying, perhaps start 25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1716 14th STREET, N.W., SUITE 200 (202) 234-4433 WASHINGTON, D.C. 20009-4309 www.nealrgross.com
22 iterating and enhancing their design, and look for 1
vulnerabilities or severe accident vulnerabilities in 2
particular, and other system vulnerabilities that they 3
can improve on.
4 But, yes, they don't -- wouldn't it be 5
better to say that it's not required? But surely you 6
want them to be developing the PRA such that it meets 7
the AS and the ANS standard by the time --
8 MS. ROSENBERG: Yes.
9 MEMBER KIRCHNER: -- they submit it at the 10 OL. So --
11 MS. ROSENBERG: Oh yeah, definitely. Yes.
12 So, this is talk --
13 MEMBER KIRCHNER: Yeah. So --
14 MS. ROSENBERG: -- this is talking just 15 about the construction permit application. And I --
16 MEMBER KIRCHNER: No, I understand that.
17 But do you want -- if they are even at the preliminary 18 stage you want them to be developing the PRA such that 19 it will meet the standard?
20 MS. ROSENBERG: Yes.
21 But, you know, and I have a -- I have a 22 few future slides that will, hopefully, clarify this.
23 MEMBER KIRCHNER: Okay.
24 MS. ROSENBERG: And then maybe we can 25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1716 14th STREET, N.W., SUITE 200 (202) 234-4433 WASHINGTON, D.C. 20009-4309 www.nealrgross.com
23 discuss it further.
1 MEMBER KIRCHNER: Well, I just want to 2
elaborate on Dave's statement. You know, David, it's 3
not required that they submit a PRA at the CP stage.
4 But you certainly want them to be developing one that 5
will meet the endorsed standards.
6 I just, maybe it's just the way the 7
vugraph reads.
8 MS. ROSENBERG: And maybe so, yes.
9 MEMBER KIRCHNER: Yeah.
10 MS. NEUHAUSEN: And Stacey just indicated 11 that there's additional slides later in the 12 presentation. And it does --
13 MEMBER KIRCHNER: Okay.
14 MS. NEUHAUSEN: -- go into how, it's really 15 how we're using ISG-28, right, and what portions are 16 applicable to a construction permit more than -- maybe 17 "misconception is not the best way to phrase that.
18 MS. ROSENBERG: We probably should have 19 said that they have to meet all of the endorsed PRA 20 standards. That's probably what it would have been a 21 better sentence if we had said that.
22 MEMBER KIRCHNER: Yeah. It's just the 23 phraseology that is kind of a disconnect for me. We 24 certainly want them to develop a PRA according to the 25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1716 14th STREET, N.W., SUITE 200 (202) 234-4433 WASHINGTON, D.C. 20009-4309 www.nealrgross.com
24 standard because --
1 MS. ROSENBERG: Yes.
2 MEMBER KIRCHNER: -- when you get to the OL 3
stage that's how you're going to review the PRA.
4 MS. ROSENBERG: Yes. Correct.
5 MEMBER KIRCHNER: Okay.
6 MS. ROSENBERG: Okay. Here's the next 7
slide.
8 Okay. This slide is a graphic of the 9
staff's approach to developing the guidance.
10 We reviewed relevant information from 11 sources such as Reg. Guide 1.70, Format and Content of 12 Safety Applications, issued in 1978.
13 And Reg. Guide 1.200, Technical Attributes 14 of an Acceptable PRA.
15 We reviewed the Standard Review Plan 16 Chapter 19, Severe Accidents, as well as recent 17 Interim Staff Guidance on Construction Permit 18 Applications.
19 At the same time, we solicited external 20 stakeholder feedback through public meetings, which 21 I'll discuss in the next slide.
22 We have and would continue to encourage 23 applicants to meet with us and in design-specific pre-24 application meetings on this topic. These meetings 25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1716 14th STREET, N.W., SUITE 200 (202) 234-4433 WASHINGTON, D.C. 20009-4309 www.nealrgross.com
25 provide an opportunity for the NRC staff's feedback on 1
design-specific questions related to Chapter 19 2
information.
3 Next slide.
4 Okay. We really collaborated, well, we 5
tried to collaborate a lot on the development. We 6
held three public meetings during the guidance 7
development. About 40 stakeholders attended each of 8
the meetings.
9 At the first public meeting in March of 10 2023 we received support from external stakeholders on 11 this initiative. We addressed external stakeholder 12 feedback by providing clarifying information on topics 13 of interest to them, to include external hazards, data 14 analysis, self-assessment for peer review, and 15 configuration control, among others.
16 Our internal team, which included members 17 from the Division of Advanced Reactors, meet weekly to 18 share ideas and insights, including similarities and 19 differences in the parallel effort for advanced 20 reactor guidance.
21 We were informed by and we utilized 22 similar concepts and materials where appropriate.
23 Okay. Now, I just want to mention a few 24 things about applicability of this guidance.
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26 This guidance is applicable to 1
construction permit applications for new light-water 2
reactors that do not use a licensing modernization 3
project framework.
4 The technical acceptability of a CP 5
application PRA may depend on the intended use of the 6
risk information and the level of design maturity at 7
the time the application is submitted.
8 Another important use of the risk 9
information is to help the NRC staff's review on those 10 aspects and to help focus our review on those aspects 11 of the design that contribute most to safety and 12 minimize attention to issues of low safety 13 significance.
14 Okay. Now we're going to get into the 15 contents of the ISG.
16 (Off-microphone comments.)
17 MS. ROSENBERG: Thank you. That wasn't a 18 question.
19 The ISG is focused on PSAR content.
20 Compared to a design certification or a combined 21 license application, the scope of information is 22 scaled down. The ISG is in a format that can be used 23 as a checklist to assist applicants with PSAR 24 preparation.
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27 At the CP stage the focus of risk 1
information in the PSAR is on description, including 2
justifications; the process of identifying and 3
dispositioning PRA uncertainties, including treatment 4
of key assumptions and key uncertainties, 5
identification of limitations, and the PRA scope, 6
level of detail, and plant representation, including 7
the impact of these limitations; and a summary of the 8
results and insights.
9 We expect the level of detail and the 10 content of different topics to vary across 11 applications, depending upon the design maturity and 12 the uses of the CP stage PRA, such as a selection of 13 licensing basis events, or demonstration of margins to 14 the Commission's safety goals.
15 CHAIR BIER: Excuse me. I have a comment 16 on that last bullet. And we may come back to this in 17 much more detail later in the discussion section.
18 My biggest question about this document is 19 not about the document itself but how it related to 20 the OL process. And conceptually I can think of the 21 CP PRA as it's done maybe with a Sharpie instead of a 22 fine-point marker, or instead of like a quarter 23 magnitude instead of three decimal places.
24 And, obviously, if there are big changes 25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1716 14th STREET, N.W., SUITE 200 (202) 234-4433 WASHINGTON, D.C. 20009-4309 www.nealrgross.com
28 before the OL, like the design change or somebody 1
discovered a failure mode that wasn't in the CP PRA, 2
obviously that has to be in the OL PRA to have the 3
applicant have responsibility to fix that.
4 But the question that I have is if there 5
is nothing wrong about the assumptions in the CP PRA, 6
if they're just very general, like that Sharpie 7
outline, would the applicant have a responsibility to 8
provide more detail?
9 So, one of the examples is, at the CP 10 stage very likely it's not yet known exactly which 11 buses are going to provide power to which equipment, 12 but that can make a huge difference in risk.
13 And is the applicant going to be required 14 to provide that level of detail at the OL stage, or 15 can they come and say, hey, my CP PRA was good enough 16 for you guys, I'm going to use it at the OL stage and 17 there's no errors? So?
18 MS. ROSENBERG: No.
19 CHAIR BIER: Okay.
20 MS. ROSENBERG: Your OL PRA, you know, is 21 going to have to be peer reviewed. It's going to have 22 to meet standards. So, so it --
23 CHAIR BIER: So, so going in at the OL 24 stage with a PRA that is kind of, you know, Sharpie 25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1716 14th STREET, N.W., SUITE 200 (202) 234-4433 WASHINGTON, D.C. 20009-4309 www.nealrgross.com
29 level without the detail about electrical support or 1
other support systems, et cetera, would not?
2 MS. ROSENBERG: No. No.
3 CHAIR BIER: Okay. That's the answer I 4
wanted to hear --
5 MS. ROSENBERG: Yes.
6 CHAIR BIER: -- so that will reduce later 7
conversation.
8 MS. ROSENBERG: Yeah, and we'll talk a 9
little bit later about configuration control which is 10 a process to get from where you are with the 11 construction permit application PRA over to your OL.
12 CHAIR BIER: And I guess the reason that 13 stuck in my mind as a question, when I was pretty new 14 on the committee I was kind of learning about all 15 these things. And the combined operating license, 16 that's a bigger issue because it's issued early on at 17 a time when the detail may not be available.
18 So, I think that's why I was kind of on 19 that.
20 MEMBER MARTIN: Stacey, I'm going in a 21 little bit different direction.
22 So, I'm going to say this is for LWRs.
23 And if the Reg. Guide 1.70 applied, you know, has a 24 traditional LWR, more than likely the applicant's not 25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1716 14th STREET, N.W., SUITE 200 (202) 234-4433 WASHINGTON, D.C. 20009-4309 www.nealrgross.com
30 going to go this route. In cases that I think of 1
NuScale being the most obvious example where, you 2
know, there's, you know, a significant novelty in that 3
LWR, no doubt, well, and the evidence is there, that 4
there are unique hazards maybe that, that seem to 5
create a point of conversation in this realm. Now, 6
for say CP I think they're going a different route.
7 But I think on that, you know, this route, 8
at the CP stage would you expect all those unique 9
events to have been identified and supported by a PRA?
10 Or could they come in and just say, well, 11 we've kind of qualitatively determined that, you know, 12 this, these are the differences at least as far as, 13 you know, of course check with the team, but of course 14 you have to, but all events to really know what side 15 of the fence you are on.
16 And, I mean, it's kind of the first 17 question. And, you know, whether you would expect 18 that PRA at that time.
19 Just start off with that question and see 20 where it leads.
21 I'm trying to work through a scenario 22 where this makes sense.
23 MS. ROSENBERG: What is the question?
24 Just, like, you know, a one-sentence question.
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31 MEMBER MARTIN: Okay. So, here's the 1
scenario.
2 And say NuScale, they've kind of taken a 3
path, say, like Kairos, or something like that, where 4
they're going right into the CP.
5 MEMBER KIRCHNER: Bob, this is Walt.
6 NuScale submitted under Part 52.
7 MEMBER MARTIN:
I'm just framing a
8 hypothetical.
9 MEMBER KIRCHNER: And maybe the GC and SBAA 10 11 MEMBER MARTIN: I'm framing a hypothetical, 12 Bob. I said that in front.
13 MEMBER KIRCHNER: No. No, but stop. Stop 14 for a minute.
15 When you go that route, one, the PRA is 16 required against the accepted standard in Reg. Guides.
17 And, secondly, the level of design detail 18 is much more complete than, than --
19 MEMBER MARTIN: Okay. Let's say, hold up, 20 with a hypothetical.
21 I, well, I know what you're saying. I 22 think you're just derailing me. All right, we'll just 23 call it --
24 MEMBER KIRCHNER:
- Well, because you 25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1716 14th STREET, N.W., SUITE 200 (202) 234-4433 WASHINGTON, D.C. 20009-4309 www.nealrgross.com
32 mentioned Kairos, which is a completely, you know, 1
it's a completely different approach in terms of the 2
level of design material.
3 MEMBER MARTIN: But we're looking at a LWR 4
that is unique. As simply as that. And I thought 5
NuScale would be a good example of the history there.
6 But apparently not.
7 But let's just call it that, an integral 8
PWR that will have deviations from what was imagined 9
in Reg. Guide 1.70. They come in kind of like what 10 we're seeing with advanced reactors with, you know, 11 leading with a CP.
12 What would you expect, you know, with 13 these differences? Can they just come in with 14 qualitative assessment of the differences? Or would 15 the staff expect the PRA in that case to defend, you 16 know, those kind of statements?
17 And then, would they become licensing 18 conditions, you know, at that stage or, or, I don't 19 know, I'm just trying to figure out the path through 20 there, what is sufficient and what can be deferred?
21 MS. ROSENBERG: I would have to ask you a 22 question or, like, re-ask it, which is what, what is, 23 what is the intent of this? What are you -- are you 24 trying to get design finality?
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33 Are you trying to say that you meet the 1
safety goals?
2 Are you trying to get SSB classification?
3 So, I guess --
4 MEMBER MARTIN: Well, it's what required at 5
the CP stage, and that's kind of where it goes.
6 MS. ROSENBERG: Okay. If it's just, if 7
they're just -- if they're not trying to get anything 8
else and they're just submitting a PRA, is that what 9
you're asking?
10 MEMBER MARTIN: No. Do they have to submit 11 that PRA when there's clear evidence that there is 12 difference between a Reg. Guide 1.70 envisioned LWR 13 and this?
14 MS. ROSENBERG: Well, I, I'm not a lawyer, 15 I'm an engineer. But I would say, you know, the 16 direction in the FRM says, says no.
17 You know, there may be, you know, if we, 18 I guess if we didn't feel that we could review it with 19 the subtleties or changes in them in a deterministic 20 manner, we might want to request a PRA.
21 MEMBER MARTIN: So, just kind of say case 22 by case basis?
23 MS. ROSENBERG: I would have to say that.
24 MEMBER MARTIN: Okay, that's fair. That's 25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1716 14th STREET, N.W., SUITE 200 (202) 234-4433 WASHINGTON, D.C. 20009-4309 www.nealrgross.com
34 the answer.
1 MR. VASAVADA: Just to answer one of the 2
parts to your question, yeah, we also find that, as 3
Stacey said, PRA is not required. And you can have 4
non-PRA based -- non-PRA risk assessments to address 5
certain cases, like Stacey said, will be case by case.
6 MEMBER MARTIN: You know, I can lay a 7
little bit more background. So, I worked on PW, P&W 8
power. And through the three application engagement 9
we qualitatively identified events that would and 10 would not be there.
11 Now, that rode the plant-specific review 12 standard process. Obviously NuScale did that and, of 13 course, took the design to finality.
14 And I'm kind of curious whether that 15 approach became truly qualitative? Now, it did lead 16 to action, the DSRS. But that, of course, is kind of 17 outside the -- you know, there's no requirement for 18 that, too.
19 So, I guess it's kind of to your point, 20 it's kind of just case by case. And it's up to the 21 staff. You know, there's no guidance really.
22 And maybe, maybe guidance is necessary or 23 not. I don't know. I mean, it's part of the 24 discussion I think.
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35 CHAIR BIER: Dennis?
1 DR. BLEY: Yeah. Thank you, Vicki.
2 And, Bob, I'm sorry, I turned my mike on 3
and forgot I had it on.
4 Back to Vicki's question kind of. I'm 5
thinking back 40, 50 years ago when we were doing a 6
lot of PRAs we, we decided to do it in a phased 7
approach. You know, phase one was to scope it and 8
figure out where to do the bulk of the work later on.
9 And one of the things we came up with, and 10 I, I think the ISG is asking for this, although 11 sometimes it's a little hard to tell, the place one 12 really ought to do a very thorough job, and has the 13 ability to do a very thorough job, is -- and again may 14 be part of the initiating events analysis and some 15 parts of the accident sequence analysis -- Bob would 16 call this hazards analysis I would think, and it goes 17 by different names depending on who's doing the work 18
-- but a really thorough search of how, what things 19 could go wrong and where they could lead if they do go 20 wrong before you'd know everything about all the 21 systems and how all the pieces fit together. Before 22 you could, long before you do a really good human 23 reliability analysis where you have procedures and 24 some experience on the machines.
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36 As I read it, it doesn't jump off the page 1
to me where it's important to do the best job and 2
where something similar can lie.
3 And somebody else made the comment about 4
PRA and other kinds of risk assessment. I guess for 5
me, you know, the old triplet idea of scenarios likely 6
having consequences is PRA. And you can do it at any 7
level of detail. So, all of those for me fit under 8
the rubric of PRA.
9 Anyway, is that kind of something you're 10 looking for or?
11 MS. ROSENBERG: Well, I think so.
12 I, you know, I think if we go a few more 13 slides maybe that will help to see what we're looking 14 for. And so maybe and if I don't answer that question 15 by Slide 14 we can revisit it; how does that sound?
16 DR. BLEY: I'm happy with that.
17 And I, I guess as I read it, if I were 18 picking this up and trying to do the PRA I'm not sure 19 it tells me where to put my emphasis and where I can 20 be more qualitative in how I look at the analysis, and 21 what my options are if I don't have a really 22 absolutely complete design at that point. Okay.
23 MS. ROSENBERG: Okay?
24 CHAIR BIER: One more question which I hope 25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1716 14th STREET, N.W., SUITE 200 (202) 234-4433 WASHINGTON, D.C. 20009-4309 www.nealrgross.com
37 will be simple.
1 Would a licensee or an applicant have the 2
opportunity to come in and say we decided to use PRA 3
for one class of scenarios and not for others?
4 So, like, we're doing PRA for LOCAs but 5
our design isn't advanced enough to do it for loss of 6
outside power, so we're addressing those concerns 7
qualitatively, or deterministically, or whatever; is 8
that something that somebody could choose to do?
9 MS. ROSENBERG: I, I would imagine that we 10 would entertain that and see if that's, if that would 11 work.
12 CHAIR BIER: Okay. Thank you.
13 MEMBER ROBERTS: This is Tom.
14 Just following up on what Bob is asking.
15 I'm trying to understand the role of this ISG.
16 Rereading the 2022 SRM that you cited, it looks like 17 that's a proposed rule that I assume you haven't 18 actually submitted yet for the Federal Register.
19 So, in terms of the role of the PRA for 20 the operating license, that's a notional concept that 21 you would then pursue in rulemaking? But I think 22 right now 10 CFR 50 doesn't require a PRA, right, as 23 far as the amplitude --
24 MS. ROSENBERG: Right.
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38 MEMBER ROBERTS: -- of 50.52?
1 MS. ROSENBERG: So, we're talking about 2
SECY 22.52; right?
3 MEMBER ROBERTS: Correct.
4 MS. ROSENBERG: So, the one that came out 5
in November of 2024.
6 MEMBER ROBERTS: Yes.
7 MS. ROSENBERG: Right. So, that, you know, 8
hasn't been finalized.
9 MS. NEUHAUSEN: This is Alissa Neuhausen.
10 Yes, so that rule doesn't exist. We're 11 just operating on those grounds.
12 MEMBER ROBERTS: Right. So, the role here 13 really is, as I understand it, and, you know, Bob's 14 question and the question whether we really understood 15 it, but I think what you're saying here is that since 16 there is a, a trend, obviously, over the last 40 years 17 to use PRA as a role in design and, you know, 18 supporting safety justification and the like, that 19 it's likely somebody will choose to use it.
20 And if they choose to use it in a 21 construction permit application then you will want to 22 have a certain, you know, measure of quality in that 23 work to understand it to the extent that you can, you 24 know, believe that it supports the justification 25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1716 14th STREET, N.W., SUITE 200 (202) 234-4433 WASHINGTON, D.C. 20009-4309 www.nealrgross.com
39 they're trying to make.
1 MS. NEUHAUSEN: Right.
2 MEMBER ROBERTS: But I think the role, the 3
role of this ISG is if someone chose to use PRA at the 4
CP stage for whatever reason, then they would want --
5 you would want them to meet these guidelines.
6 And getting to Bob's example, if someone 7
was close enough to Reg. Guide 1.70 that they didn't 8
think they needed to use PRA at all, then this ISG 9
wouldn't apply and you would then be in a position of 10 judging the adequacy of the CP application against 11 truly qualitative and deterministic methods, and maybe 12 you'd get there and maybe you wouldn't. But then this 13 ISG wouldn't apply.
14 So, the whole idea that of an OL requiring 15 a PRA, you might meet the quality event, seems like a 16 side issue, that's all future in terms of what comes 17 out of the rulemaking that's still in process. So, so 18 I do understand that.
19 MS. NEUHAUSEN: The rule is going to 20 happen. And I'll just add, go a little bit farther.
21 The ISG was also put together because 22 there was interest from industry. So it wasn't us, 23 you know, looking at it, there was there are 24 applicants who are looking at Part 50 that are 25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1716 14th STREET, N.W., SUITE 200 (202) 234-4433 WASHINGTON, D.C. 20009-4309 www.nealrgross.com
40 interested in using a PRA and want to know what are 1
expectations of staff.
2 MEMBER ROBERTS: Right. Getting to Bob's 3
hypothetical, I think the answer to this question is 4
yes.
5 If somebody could get through the entire 6
application process where you strictly, you know, 7
general design criteria in Reg. Guide 1.70, stay away 8
from PRA, today they could do that. They would just 9
have discussions and did they really identify all the 10 hazards.
11 And that's part of the, you know, the 12 regulatory evaluation process is did they do enough to 13 identify all the hazards? And if they did, great.
14 And this ISG is, you know, something they wouldn't 15 have to consider 16 So, I just wanted to verify I understood 17 the purpose of this. Thank you.
18 MS. ROSENBERG: Sure.
19 Okay. So, I guess we'll continue.
20 Next slide.
21 Okay. I think we're on the development 22 approach.
23 CHAIR BIER: What I have is internal 24 events, so I think we're in the right place.
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41 MS. ROSENBERG: Okay, perfect.
1 Okay, so this table, this slide is a 2
reproduction of Table 1 from the ISG. And it 3
represents, along with the information on the next 4
slide, what the staff considers the minimum scope of 5
the PRA and non-PRA assessments of the CP stage.
6 Again, this is guidance and not a 7
requirement.
8 The applicant should perform an at-power 9
internal event PRA that meets Capability Category 1 of 10 the endorsed PRA standard for those technical elements 11 of the internal event PRA that can be reasonably met 12 at this stage in the design.
13 Okay. So, I'm not going to plan to go 14 through each of the elements listed in the table.
15 I'll just take one example, data analysis.
16 So, for the PSAR application it should 17 include a discussion of sources of initiating event 18 frequencies and failure rates; discussions for the use 19 of generic estimates; justification for failure rate 20 use for first-of-a-kind components; and appropriate 21 uncertainty and sensitivity analysis.
22 Okay. We're going to move on to --
23 MEMBER KIRCHNER: This is Walt Kirchner 24 again. I wanted to follow up on Bob and Dennis' 25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1716 14th STREET, N.W., SUITE 200 (202) 234-4433 WASHINGTON, D.C. 20009-4309 www.nealrgross.com
42 question and see if I can phrase it differently.
1 This is a long list. It's a complete 2
list. And what struck me, perhaps a variation of what 3
Dennis was saying, what struck me is you're certainly 4
complete in all the elements on these two tables as to 5
what you want to see in a PRA certainly by the time 6
you get to the OL stage.
7 But where should the emphasis go? For 8
example, the human reliability analysis, isn't it a 9
little bit premature?
10 If you don't really have a detailed 11
- design, Bob's hypothetical
- design, that's not 12 something comparable to NuScale where you have a very, 13 very mature and complete design, how much effort do 14 you want to put into something like human reliability 15 analysis, or even data analysis? Because you don't 16 have procurement specs for components and so on.
17 So, where do you expect and where would 18 you want to see an applicant actually using PRA at 19 this stage?
20 What I'm, what I'm trying to say is it 21 struck me reading the ISG, it's very complete, very 22 detailed. But what's the appropriate area, what are 23 the appropriate areas for emphasis at this stage, 24 especially if you don't have a very complete design?
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43 MS. ROSENBERG: So, first of all, I do want 1
to point out that there at the end it says "Capability 2
Category 1 is acceptable for a CP application.
3 So, and there will be several supporting 4
requirements that won't be able to met -- be met at 5
this stage. And maybe a lot of them will fall in 6
human reliability analysis. But we would think that 7
you would go through the steps of the PRA nonetheless, 8
and go through what you can evaluate, and document 9
what the limitations are because of the stage that 10 you're at.
11 Any questions?
12 MEMBER DIMITRIJEVIC: I just want to add 13 the comment of -- it's Vesna Dimitrijevic. First of 14 all to actually go back to his first question, you 15 know, first comment when he objected to this guidance 16 when you have overcoming misconception construction 17 that it must meet PRA standards.
18 Those are exactly categories from the PRA 19 standard and you're expecting them to meet the 20 Capability Category 1, that is in conflict with what 21 you said in objectives; right? So, you do expect them 22 to meet category -- the Capability 1 of that PRA 23 standard. And those are the PRA standards that 24 categories which you can list, have listed in this 25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1716 14th STREET, N.W., SUITE 200 (202) 234-4433 WASHINGTON, D.C. 20009-4309 www.nealrgross.com
44 table.
1 Also, the PRA standards, you know, have 2
these categories which increase in the level based on 3
this hope of the realism and plans specificity; right?
4 And this Category 1 is the lowest one, so it has the 5
lowest level of the scope can be done on much higher 6
level than necessary. It is notifying for plant 7
specificity, is that level of realism it has to be 8
just good enough to satisfy whatever conclusions there 9
can be.
10 So, this is just what I want to add as a 11 comment. You contradict your previous statement.
12 MS. ROSENBERG: Okay. Let me, let me read 13 the statement though, because I don't want to 14 contradict it.
15 What I said was the applicant should 16 perform an at power internal event PRA that meets 17 Capability Category 1 of the endorsed PRA standards 18 for those elements, those technical elements of the 19 internal event PRA that can be reasonably met at this 20 stage of the design.
21 So, there are going to be several elements 22 that because of the design readiness or not will not 23 be able to be met.
24 So, what I guess I'm saying --
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45 MEMBER DIMITRIJEVIC: Yes, but you know, 1
this is just like that a certain, you know, it's 2
obviously that is element which cannot meet the, you 3
know, the plan specification stages that is the 4
elements which cannot be met after the plant is 5
operational, and you have the plant-specific data.
6 But that will mean, that will be that it's 7
not expected to meet the standard to the level --
8 MS. ROSENBERG: Right.
9 MEMBER DIMITRIJEVIC: -- which can be met 10 in this stage.
11 So, I just think that you should really --
12 well, that's okay. I thought statement like that is 13 not in the ISG. So, you know, I was going to do 14 research for that.
15 But all right. The point is you expect 16 them to meet standards to the point which can be met 17 to the level of the details, and really some plant 18 specificity which can be met in this stage.
19 MS. ROSENBERG: I will go through the ISG.
20 I thought we clarified that in the ISG. But, if not, 21 we'll look back at it.
22 CHAIR BIER: Dennis?
23 DR. BLEY: Yeah. This is Dennis Bley 24 again.
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46 Everything you said is -- true is not 1
quite the right word, but fits the problem. What I 2
want to suggest to you is that rather than focus on 3
Capability Category 1, which doesn't really give you 4
-- it's set up and then hardly anything is necessary, 5
and nothing needs to be plant specific -- when what we 6
really want out of this kind of analysis at this early 7
stage is what I said earlier about completeness on the 8
scenarios, but what we want is a report that tells us 9
what are the knowledge gaps?
10 What's missing at this time? How 11 important are they? And what's the plan for filling 12 in those knowledge gaps as the design progresses?
13 And I think a requirement to have that 14 kind of report would be much more beneficial to an 15 applicant and to the NRC staff.
16 MS. ROSENBERG: I think --
17 DR. BLEY: And a way to meet Capability 18 Category 1.
19 MS. ROSENBERG: I think it's in here. I do 20 think it's in here.
21 So, if I could get through a few more 22 slides, and then we could, we could talk about it.
23 And certainly if we're missing something we'll 24 definitely add it.
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47 But I do, I do think it's in here. Maybe 1
I'm moving too slow.
2 So, unless there's another question here, 3
I'm going to move on to hazards, the next slide.
4 Okay. So, this slide is a reproduction 5
also of Table 2 in the ISG.
6 Okay, so for hazards the right column 7
provides non-PRA assessments that should be included 8
in the PSAR.
9 The left column is, are those PRA aspects 10 of that hazard, like internal flood PRA vs. internal 11 flood risk evaluation. And they can be provided 12 instead of the non -- the alternate risk evaluations.
13 It's up to the applicant.
14 But the minimum is the, is the right 15 column.
16 Use of PRA beyond the minimum expectations 17 will result in detailed risk insights as well as an 18 easier transition between construction permit and 19 operating license reviews for the staff. So, I just 20 wanted to point that out.
21 So, it's basically one, either column, 22 either the left column or the right column for a 23 construction permit application.
24 Next slide.
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48 Okay. So, now here --
1 DR. BLEY: This is Dennis. This is Dennis 2
again. Quick question back on your last slide.
3 When you say not PRA, I take it you mean 4
not a full set of event trees and fault trees rather 5
than not the trickwood idea. Is that right?
6 MS. ROSENBERG: Right. Right.
7 DR. BLEY: Okay.
8 MS. ROSENBERG: These are risk evaluation 9
that's just not PRA.
10 Okay. All right, so technical elements.
11 DC/COL-ISG-028, which is titled Assessing 12 the Technical Adequacy of Advanced Light-Water Reactor 13 PRAs for the Design Certification and Combined License 14 Application, provides staff positions on supporting 15 requirements in the PRA standard that are not 16 applicable or cannot be achieved as written for the DC 17 and COL application stage.
18 We can use this for construction permit 19 applications. ISG-028 is one example of guidance that 20 can be used to determine which supporting requirements 21 of the PRA standard are applicable or needed to meet 22 high level requirements for a construction permit 23 application.
24 Okay?
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49 And with that, you would only need 1
Capability Category 1.
2 Next slide, please.
3 Okay. Now I just want to talk a minute 4
about seismic.
5 For seismic an applicant could perform a 6
PRA or an alternative risk evaluation. And the 7
alternative risk evaluation usually for seismic would 8
be a PRA-based seismic margin assessment, SMA.
9 Since site-specific information is 10 available at the CP stage, an applicant may have 11 additional options and choice of response spectra 12 compared to a Part 52 design certification.
13 A
PRA-based estimate considers all 14 sequences leading to core damage or containment 15 failure. The primary difference between a PRA-based 16 SMA and a seismic PRA is that the PRA-based SMA, for 17 the PRA-based SMA the convolution of fragilities and 18 the plant seismic hazard curve is not performed.
19 One example of a PRA-based SMA is in the 20 NuScale application.
21 For a PRA-based SMA an applicant can 22 either use site-specific response spectra or a design 23 response spectra. If a site-specific response spectra 24 is used, site-specific seismic induced initiating 25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1716 14th STREET, N.W., SUITE 200 (202) 234-4433 WASHINGTON, D.C. 20009-4309 www.nealrgross.com
50 events should be identified.
1 If a design response spectra approach is 2
used which is representative of multiple sites, the 3
applicant should demonstrate that the site-specific 4
ground motion response spectra is bounded by the 5
design response spectra.
6 The PSR should also include a description 7
of seismic fragility evaluation, including 8
justification if generic fragility values are used, 9
and a description of the plant response analysis and 10 the resultant site change.
11 This next slide on non-seismic hazards is 12 a graphic representation of an approach that can be 13 used to evaluate non-seismic hazards at the 14 construction permit stage. Non-seismic hazards 15 includes those identified in Table D1 of Appendix D to 16 Reg. Guide 1.200, including high winds, external 17 floods, pipeline explosions, aircraft impacts, and 18 many others.
19 Each non-seismic hazard should be 20 evaluated to see if it can be screened. For hazards 21 that are screened the applicant should describe the 22 qualitative or quantitative screening criteria and a 23 description of the site-specific screening evaluation.
24 If a hazard cannot be screened, an 25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1716 14th STREET, N.W., SUITE 200 (202) 234-4433 WASHINGTON, D.C. 20009-4309 www.nealrgross.com
51 applicant could then choose whether to perform a PRA 1
or an alternative risk evaluation, conservative 2
estimate of risk.
3 The asterisk on this slide points out that 4
hazard screening would need to be reevaluated at the 5
operating license stage.
6 Okay. All right. Low power and shutdown.
7 Either a low-power and shutdown PRA or an 8
alternative risk evaluation can be used for a CP 9
application.
10 A description of any analysis performed to 11 screen plant operating
- states, including 12 identification of any design features relied on for 13 the screening, should also be provided.
14 Also, a description of the low-power 15 shutdown risk insights, key assumptions, and any 16 limitations arising from the level of design maturity 17 and operational detail should be provided.
18 Next slide. Okay.
19 Self-assessment vs. peer review.
20 A self-assessment of the PRA of the risk 21 information would be an acceptable tool for assessing 22 the technical acceptability of the PRA of CP 23 application.
24 The guidance in ISG-028 is generally 25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1716 14th STREET, N.W., SUITE 200 (202) 234-4433 WASHINGTON, D.C. 20009-4309 www.nealrgross.com
52 applicable. We recognize that there may be some 1
deviation since the design certification application 2
may have a more mature design where a construction 3
permit application has information on site 4
characteristics.
5 Applicants may use the process in PRA 6
Standard 1.3, Risk Assessment Application Process, and 7
a flow chart 1-3-1, to help decide which supporting 8
requirements are applicable.
9 The applicant should provide a summary of 10 the results of the self-assessment or peer review 11 which would include any associated limitations. For 12 example, aspects of the PRA that were not able to be 13 fully reviewed due to the design status and site 14 limitations.
15 While either a self-assessment or a peer 16 review may be used to demonstrate the acceptability of 17 the PRA at this stage, the peer review would provide 18 additional confidence in the results.
19 Let's go to the Slide 17.
20 MS. ROSENBERG: Configuration control. A 21 description of the configuration control program will 22 demonstrate that the applicant has established an 23 acceptable process for upgrading and updating the PRA 24 as the design progresses, leading up to operating 25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1716 14th STREET, N.W., SUITE 200 (202) 234-4433 WASHINGTON, D.C. 20009-4309 www.nealrgross.com
53 license application. The PSAR should describe the 1
technical elements that cannot be met and the reasons 2
why, the process to track assumptions and changes to 3
PRA and how new information will be included 4
consistent with as-built as to be operated plant 5
design.
6 Next slide, severe accidents. For severe 7
accidents, examples of which include core concrete 8
interactions, steam explosion, hydrogen combustion and 9
containment bypass, and others, the PSAR should 10 include a description of design features for the 11 prevention and mitigation of severe accidents, a 12 description of improvements to the plant, operation or 13 maintenance that prevent or reduce the possibility, 14 likelihood or consequence of severe accidents, an 15 evaluation of the severe accident phenomena to assess 16 their design relative to the containment performance 17 goals as approved in SRM-SECY-93-87, which is policy, 18 technical and licensing issues pertaining to 19 evolutionary and advanced light-water reactor designs.
20 Okay. RTNSS, the regulatory treatment of 21 non-safety systems. SECY-94-84 and SECY-95-132 22 describe the scope, criteria and specific steps of the 23 RTNSS process.
24 Staff follows SRP Chapter 19.3 when 25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1716 14th STREET, N.W., SUITE 200 (202) 234-4433 WASHINGTON, D.C. 20009-4309 www.nealrgross.com
54 reviewing an applicant's application of RTNSS. The 1
RTNSS process applies to those non-safety-related 2
active systems in designs with predominantly passive 3
safety systems that perform the risk significant 4
functions and therefore are candidates of regulatory 5
oversight.
6 A RTNSS evaluation is not required at CP 7
application stage. Nevertheless, if an applicant 8
provides a RTNSS evaluation and requests a regulatory 9
finding on RTNSS at the CP stage, risk evaluations of 10 all modes and all hazards would need to be provided.
11 So with that, I will ask if you have any 12 questions. That was a summary of -- that was a short 13 summary of what is in our guidance document. And if 14 no questions, I will hand it over to Alissa Neuhausen, 15 who will go over the comments that we received and our 16 dispositions of the comments.
17 CHAIR BIER: I do have a few questions.
18 MS. ROSENBERG: Sure.
19 CHAIR BIER: Oh, go ahead, Dennis, if you 20 want to --
21 MEMBER PETTI: This is Dave.
22 CHAIR BIER: Oh, I'm sorry.
23 MEMBER PETTI: Just a quick one. Do you 24 have to have uncertainties at this stage?
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55 MS. ROSENBERG: Yes. Yes. I'm sorry.
1 Uncertainties are very important at this stage.
2 CHAIR BIER: Okay. A couple of questions.
3 One just on this slide. If the staff provides a RTNSS 4
evaluation at the CP stage, is that kind of assumed 5
carried over to the OL stage or it would need to be 6
redone?
7 MS. ROSENBERG: If the staff has enough 8
information to perform a RTNSS evaluation and make a 9
finding, I don't see why it would need to be 10 reperformed. There may be some action items included 11 that would need to be looked at.
12 But I think that -- you know, because if 13 an applicant wants a RTNSS evaluation at the CP stage, 14 then RTNSS is very prescriptive. There is a lot that 15 is in RTNSS. And, you know, they would have to 16 provide a full scope PRA.
17 CHAIR BIER: Okay. Thank you.
18 MS. ROSENBERG: So --
19 MEMBER MARTIN: Well, I'm late to RTNSS 20 and of course the topic in general. I feel like at 21 the CP stage -- again, we're talking just light-water 22 reactors -- the applicant would come in with a very 23 specific objective because these are really just 24 provisions from the standard, Reg. Guide 1.70.
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56 I think an objective wouldn't be a full 1
review of anything. It would be a targeted delta 2
review of what they need. We can hear that later as 3
you died your -- you know, I had to go -- I dug up, to 4
answer my earlier question about what does the 5
environmental report folks do.
6 And at the CP stage, all they say is the 7
CP application should provide the best information 8
available to assess SAMA and SNDRS. There is no 9
capability category, statement. It's just the best 10 available, which is all you really have at the CP.
11 So, you know, and maybe you're going to 12 get into in a second on public comments, but certainly 13 my immediate reaction is this needs to be controlled 14 a little bit to target what is essential at that stage 15 and shouldn't trigger major reviews. It should be 16 focused on best information available, consistent with 17 what they are already doing within ER.
18 MS. ROSENBERG: Absolutely. This was just 19 to -- there are some licensees that feel they have a 20 certain readiness at, you know, construction permit.
21 And if they are interested in getting certain 22 finality, you know, we are going to review it for 23 them.
24 MEMBER MARTIN: That's probably what they 25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1716 14th STREET, N.W., SUITE 200 (202) 234-4433 WASHINGTON, D.C. 20009-4309 www.nealrgross.com
57 get for it. I mean, I don't know. Are you just a 1
glutton for punishment sometimes? You would hope 2
that, you know, their licensee people will say, all 3
right, we are going to take a very measured approach 4
to our review here and not ask for trouble, but.
5 MR. VASAVADA: This is Shilp from the 6
staff. To your point and to Stacey's point, the 7
regulations do allow licensees to identify any aspect 8
when they need a final decision at the CP stage. So, 9
again, it depends upon the license of the applicant to 10 determine where they are on their spectrum and what 11 they want. And as Stacey said, we will adjust 12 accordingly.
13 MEMBER MARTIN: Nothing is final at this 14 stage.
15 CHAIR BIER: Vesna?
16 MEMBER DIMITRIJEVIC: Yes. I have a -- I 17 have a question. But before my question, I want to 18 make a comment on something which you said for Dave.
19 You said that the applicant is supposed to do 20 uncertainty analysis. But this was one of mine main 21 concerns when I was reading through this.
22 This is not typical in the sense the 23 analysis that is done that here that should be more 24 identifying sources of uncertainty. Because if you 25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1716 14th STREET, N.W., SUITE 200 (202) 234-4433 WASHINGTON, D.C. 20009-4309 www.nealrgross.com
58 don't have in a sense complete, you are at a different 1
stage of completing design doing the certainty parts 2
doesn't make any sense because it is difficult to 3
estimate uncertainties of so many incompleteness.
4 So uncertainty analysis should be 5
different than what is expected. The more we develop 6
PRA is more just identify sources of certainties and 7
how could they impact the results. That was just a 8
comment on what you said on uncertainty analysis.
9 My question is connected, but you have in 10 this ISG separated some discussion on passive 11 components and so if it is connected with the passive 12 components and also you have this RTNSS for the 13 passive -- separated for passive components. Can you 14 comment on that, why and how you separated then make 15 action from these, you know, passive features.
16 MS. ROSENBERG: I'm not sure I understood 17 the question. Did you?
18 MEMBER DIMITRIJEVIC: For the separation 19 from what we see, usually, you know, the guidance, 20 here you added these passive -- you have a section in 21 ISG, for example, a section is called, regulatory 22 treatment on non-safety system for designs with 23 passive safety systems, right? And then you have also 24 previously that covers the end. And you have passive 25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1716 14th STREET, N.W., SUITE 200 (202) 234-4433 WASHINGTON, D.C. 20009-4309 www.nealrgross.com
59 safety system reliabilities subsection. What was your 1
main concern about passive systems and why are those 2
sections there?
3 MS. NEUHAUSEN: So I don't know that there 4
was any particular concern with passive systems, but 5
we do expect, you know, designs that we previously 6
made would have come in under Part 52 that were 7
passive designs, I think we are expecting to see those 8
in the construction permit come in under Part 50, and 9
so we wanted to address those in Part 50.
10 And for RTNSS, that's, you know, I think 11 we followed something similar to our SRP. So RTNSS 12 has a separate, you know, SRP Section 19.3. So that 13 had its own section in this ISG and then also SRP 19.0 14 I don't know if there's a heading for it. But there 15 is a specific discussion of passive safety system 16 reliability. And so we were -- consistent with the 17 SRP, which we used for Part 52.
18 MEMBER DIMITRIJEVIC: Well, see, this is 19 sort of disappointing also to me because I thought you 20 tried to make an additional step that connecting to 21 uncertainties. And you discussed this very well on 22 this thermal hydraulic type uncertainty in this 23 passive system reliability. And that was the concern.
24 And also in this last section on the --
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60 let me just find that. So I thought that you had made 1
some time to introduce something new here because most 2
of other things is just, you know, the PRA standard, 3
the connection. No safety systems which -- you also 4
have discussion that non-safety system, which result 5
in actuation of passive systems should be situation.
6 So, okay. I mean, I thought that that was some 7
attempt in something, you know, new. So all right.
8 CHAIR BIER: Dennis?
9 DR. BLEY: I want to get back to the thing 10 I asked earlier. As you went through the slides, 11 especially the ones describing what needed to be in 12 the preliminary safety analysis report, you kind of 13 covered the things I was looking at.
14 And I see bullets scattered through the 15 ISG that hit on this. But I think something concise 16 saying one of the key things we want to see out of 17 this PRA is identification of the knowledge gaps in 18 each area, what's missing. And Vesna's comment about 19 what you can do with uncertainty is right. But you 20 have a bullet on that, sources of uncertainty need to 21 be described. But somewhere to say we want to know 22 exactly what is not there, how important it might be 23 and what's the plans for gathering that data in the 24 future, if it's data or if it's new analysis. It just 25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1716 14th STREET, N.W., SUITE 200 (202) 234-4433 WASHINGTON, D.C. 20009-4309 www.nealrgross.com
61 doesn't leap off the page to me.
1 I think you're right. It's kind of 2
scattered around everywhere and sort of covered. But 3
to me that's one of the big things you would want to 4
see out of this. So for your later reviews it would 5
help you focus. And for the applicants later work 6
without them focus as well. And I don't see it 7
concisely stated anywhere.
8 MS. ROSENBERG: Thank you.
9 CHAIR BIER: I have a few questions from 10 my read of the document, most of which are pretty 11 minor. One of them relates to some of the discussion 12 we just had on uncertainty. But I will just go 13 through chronologically and raise them just for you to 14 consider.
15 Under event sequence analysis, I am an 16 event tree person. So I had no problem with the 17 statement, a summary of the event tree for each 18 initiating event. But back a while ago, there was 19 still people doing large fault-tree models. Is that 20 still a thing and are you intending to preclude that 21 or is that just an oversight in the way this is 22 written or what are you anticipating?
23 MS. ROSENBERG: I think I will have to 24 look into that.
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62 CHAIR BIER: That's fine. Let me see.
1 Okay. Under uncertainty analysis, you talk about CDF 2
and LERF. And CDF obviously is because this is for 3
light-water reactors.
4 Have you thought about what a CP PRA might 5
start to look like for other reactor designs where CDF 6
would not be the main metric and would most other 7
things in this document look similar or that is really 8
premature and you haven't discussed that yet.
9 MS. ROSENBERG: We haven't discussed this 10 as a part of this opening question.
11 CHAIR BIER: So you're thinking about it 12 but nothing at this stage to share? Okay.
13 So the next comments that I have really do 14 deal with this topic of uncertainty. And this is 15 going to be discussed in much more detail this 16 afternoon. So some of you may want to tune in then if 17 you are available.
18 But, you know, one question is just is it 19 possible for uncertainties to be too large that you 20 might look at that and say, hey, these people don't 21 know what they are doing enough to be ready to have a 22 CP.
23 The other question, which is more related 24 to what the other discussion has been is just I would 25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1716 14th STREET, N.W., SUITE 200 (202) 234-4433 WASHINGTON, D.C. 20009-4309 www.nealrgross.com
63 assume that large uncertainties would be assigned that 1
some further research or data collection or design 2
enhancement or whatever would be needed to address 3
those uncertainties. So do you want to talk a little 4
bit about how the uncertainty would be used?
5 MS. ROSENBERG: You know, uncertainty is 6
a cross-cutting issue, right? So I guess it would be 7
used to see if there are any outliers, you know, just 8
that we can't -- that need to be solved, need to be --
9 CHAIR BIER: Yeah.
10 MS. ROSENBERG: -- evaluated --
11 CHAIR BIER: Okay.
12 MS. ROSENBERG: -- to deal with, yeah.
13 CHAIR BIER: I think that's fine. That's 14 what I would expect. But, again, maybe it's just not 15 as clear in the write-up or summarized concisely.
16 MS.
ROSENBERG:
Because we have 17 uncertainties everywhere in each segment.
18 CHAIR BIER: Okay. I think this is my 19 last comment, which is really one that -- I think my 20 confusion is just a wording issue again. It says the 21 PRA configuration plan should include a description of 22 the applicant's plan for addressing the PRA elements 23 identified as inapplicable or not plainly a well PRA.
24 I think, you know, what things are inapplicable or not 25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1716 14th STREET, N.W., SUITE 200 (202) 234-4433 WASHINGTON, D.C. 20009-4309 www.nealrgross.com
64 meant in the CP and PRA that will then be addressed 1
2 MS. ROSENBERG: What page are you on?
3 CHAIR BIER: Page 26, I think, the first 4
bullet under configuration plan. You might just want 5
to like highlight that and go look at it.
6 MS. ROSENBERG: I believe the statement is 7
asking for the OL to address those things that we were 8
talking about.
9 CHAIR BIER: I assumed that's what you 10 meant. I just wanted to double-check. And I think 11 that summarizes my comments. So there is no other 12 comments or --
13 MEMBER MARTIN: I have a couple comments.
14 CHAIR BIER: Okay.
15 MEMBER MARTIN: Okay. I'm going to --
16 CHAIR BIER: As usual.
17 MEMBER MARTIN: -- again slice and dice on 18 the level of detail. So after it comes in -- again 19 love my scenarios -- with a qualitative argument but 20 then provides kind of -- I can just say a capability 21 category one PRA, really more as a confirmatory role.
22 They are leading with the qualitative arguments. But 23 to support those arguments, they are providing PRA 24 insights. Does that trigger all of this extra review?
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65 Can you move forward with assessing the 1
qualitative consistent with, you know, past practices 2
and not go into -- and not recognize it as really a 3
PRA submittal at the CP stage. Is there that 4
discretion?
5 And, I guess, I think I just answered a 6
question based on our earlier conversation that it's 7
case-by-case to some extent, right? I'll let you --
8 it's not easy there, Stacey.
9 MS. ROSENBERG: It depends on design 10 readiness.
11 MEMBER MARTIN: Right.
12 MS. ROSENBERG: Right? And what the 13 application is being asked for, right? So your 14 scenario could go through if nothing specific is being 15 asked for at that time.
16 MEMBER MARTIN: Well, I mean, they would 17 be asking for -- you know, they would be presenting 18 their events, right? What is and is not a severe 19 accident? You know, what are the deviations in, you 20 know, the design basis space? What are unique 21 hazards? But they are presenting them, you know, in 22 a point-by-point kind of basis, qualitative arguments.
23 And then it wouldn't be unusual for them 24 to say the technical basis for those decisions draw on 25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1716 14th STREET, N.W., SUITE 200 (202) 234-4433 WASHINGTON, D.C. 20009-4309 www.nealrgross.com
66 PRA insights. And then, you know, I mean a judicious 1
approach to the review might for the applicant to 2
submit only the qualitative and then have the 3
documents with the PRA kind of in reserve for review.
4 And I am not sure that gets submitted. It 5
would be recognized as being a submission. It would 6
just be a peripheral document supporting their initial 7
arguments.
8 MS. ROSENBERG: I think if they have a PRA 9
to support their arguments, so much the better.
10 MEMBER MARTIN: Right, right. Thanks. I 11 am just concerned that we are just triggering more 12 than is necessary on a review standpoint. And that 13 they have, you know, at the CP stage you get into the 14 weeds, when, you know everybody has been involved in 15 the design process, known as a whack-a-mole, right?
16 Something is wrong. You change it, and it affects 17 other things. And your PRA is the one thing that just 18 gets whacked, you know, all the way through the design 19 process. And so it is moving a lot.
20 MS. ROSENBERG: But we like to see that, 21 you know? You know what I mean? Like if something 22 changes and PRA has to change --
23 MEMBER MARTIN: Right.
24 MS. ROSENBERG: We like to see the 25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1716 14th STREET, N.W., SUITE 200 (202) 234-4433 WASHINGTON, D.C. 20009-4309 www.nealrgross.com
67 configuration control document that and what's 1
changed. And maybe that -- it's changed because of 2
something in the PRA. And so we like to see, you 3
know, this design we changed this because we saw 4
something in the PRA. And so we made the changes, and 5
now we are doing it this way.
6 MEMBER MARTIN: Yeah. I guess my concern 7
would be if the review starts becoming a distraction 8
to the design process, it has its own kind of impact 9
on safety, right?
10 If you have an applicant going off 11 answering questions at the CP stage because of some 12 perceived incompleteness with a PRA, they are not 13 doing other things that might lead towards a better 14 design. So being around it is a safety issue if we 15 just tighten up the focus on reviews at this stage.
16 And I guess I am going to fault on maybe 17 this capability category one might even be too much 18 even though Dennis already kind of acknowledged it is 19 pretty open ended at this point, but best available 20 information. More delta review kind of targets 21 focusing on the end products of why they might 22 otherwise submit these things.
23 But I agree, I mean, internally PRA or 24 more now. Certainly, we see it with the advanced 25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1716 14th STREET, N.W., SUITE 200 (202) 234-4433 WASHINGTON, D.C. 20009-4309 www.nealrgross.com
68 reactor designs, yes. I mean, they are moving along 1
with design process. But this is all happening very 2
much in real time. Designs are a changing dynamic.
3 And you can't necessary share that all 4
with a regulator. It is just moving too fast and to 5
share everything is really asking too much. A roll-up 6
once in a while and, you know, a pre-application 7
meeting, that's nice. But that's, you know, again, a 8
design expectation.
9 But there has got to be some limits on the 10 overall scope of review because this could really, you 11 could really take it too far. So anyway, it's all 12 setting the parameters for it.
13 CHAIR BIER: Okay. If there's no further 14 questions or comments, then Alissa, I assume, your 15 part is going to be pretty quick and then we can plan 16 to take a break after that. Is that --
17 MS. NEUHAUSEN: Yeah. I am going to 18 address the comments and then the -- I think NEI is 19 going to talk about the comments.
20 CHAIR BIER: I think we will take a break 21 before NEI and after your part. Thank you. Go ahead.
22 MS. NEUHAUSEN: So we received 12 comments 23 during the public comment period. Nine of them were 24 for NEI and three of them were for NuScale. Staff has 25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1716 14th STREET, N.W., SUITE 200 (202) 234-4433 WASHINGTON, D.C. 20009-4309 www.nealrgross.com
69 agreed with five of the comments and made changes to 1
the ISG. And we partially agreed with three comments 2
and made changes to the ISG. And there were four 3
comments and made no changes to the ISG.
4 For the next couple of slides --
5 CHAIR BIER: Pull your mic a little 6
closer. Yeah.
7 MS. NEUHAUSEN: I have broken up the next 8
seven slides into -- instead of agreed/disagreed, they 9
are more based on topic area.
10 So two comments requested additional 11 clarity. Staff agreed on amending the ISG to clarify 12 that the ISG provides guidance on the staff review of 13 the descriptions in the SCR not on the acceptability 14 of the PRA.
15 The staff responds and clarifies that the 16 guidance is for the PRA information required to be 17 reviewed for a CP if PRA information is used in the 18 submittal as we discussed earlier.
19 Five comments requested clarity for 20 adjustments to the minimum elements in scope of the 21 PRA. Staff agreed, partially agreed and disagreed 22 with various portions of these comments.
23 Staff modified the ISG to clarify that the 24 minimum scope for a CPA that uses PRA information is 25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1716 14th STREET, N.W., SUITE 200 (202) 234-4433 WASHINGTON, D.C. 20009-4309 www.nealrgross.com
70 an at power internal events PRA. If PRA information 1
for other hazards is used to support the CPA, staff 2
would review those hazards. Otherwise, staff will 3
focus on the applicant's plan for assessing risk 4
contributors not addressed by a PRA or alternative 5
risk valuation in the OLA.
6 Staff did not modify the ISG to remove a 7
discussion of preliminary results or risk evaluations 8
from its review. At the CPA, all results are 9
preliminary. However, we believe the comment is 10 addressed by not requiring hazards other than integral 11 events.
12 Staff modified the ISG to clarify that a 13 PRA is not required to determine licensing basis 14 events for a Part 50. Staff agreed there may be 15 hazards for which a PRA does not offer additional 16 insights at the CP stage. And if PRA information is 17 not used for these hazards to support the CPA, staff 18 would not review them.
19 Hazard risk evaluations are not required, 20 consistent with SRM 232-0052 as long as they are not 21 used to support the construction permit application.
22 One comment stated that the hazard 23 assessment requirements go beyond traditional design 24 requirements for safety-related SSEs.
25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1716 14th STREET, N.W., SUITE 200 (202) 234-4433 WASHINGTON, D.C. 20009-4309 www.nealrgross.com
71 All hazard assessments are not required 1
for the construction permit application. So the staff 2
will look for some assurance that the applicant has 3
considered potential impacts and hazard assessments.
4 And further the PRA used in a confirmatory manner does 5
not convey design requirements.
6 One comment requested additional 7
clarification that supporting requirements may not be 8
applicable or may not be reviewed. The staff 9
reiterated an existing discussion in the ISG to make 10 it clear to staff that all supporting requirements 11 endorsed in industry standards may not be applicable 12 to a CP. I think we discussed that one earlier.
13 One comment requested references for 14 alternative risk evaluations. In this ISG, staff is 15 not endorsing a particular alternative risk evaluation 16 in the guidance. Prior applications can be reviewed 17 for previously used methodologies.
18 One comment requested a change to a 19 statement to include in the ISG on passing safety 20 system reliability. The statement that we used is 21 consistent with SRP Section 19. It indicates to the 22 staff why passive safety system reliability may be 23 important to certain reviews.
24 Obviously, we are not necessarily stating 25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1716 14th STREET, N.W., SUITE 200 (202) 234-4433 WASHINGTON, D.C. 20009-4309 www.nealrgross.com
72 in the ISG that this statement is applicable to all 1
review although that statement is important for 2
reviewers in understanding their role for reviewing 3
the construction permit application PRA.
4 And the last one -- one commenter 5
requested that the guidance verify that RTNSS may not 6
be identified for all passive plant designs. So we 7
clarified that this may be the case. The resolution 8
to the comment discusses that the process for 9
identifying RTNSS should determine that output but 10 consistent with design certification reviews there may 11 not be RTNSS identifiable at all times.
12 That's all the comments.
13 CHAIR BIER: Okay. Any further questions 14 or comments for staff before we take a break? Well, 15 we have an external comment with the hand raised, but 16 I think we will take that later in the time for public 17 comments if that's acceptable.
18 So with that, I think we are on break and 19 be back around 10:20 to hear from NEI.
20 (Whereupon, the above-entitled matter went 21 off the record at 10:06 a.m. and resumed at 10:20 22 a.m.)
23 CHAIR BIER: We are now back in session 24 after break and ready to hear from Jon Facemire from 25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1716 14th STREET, N.W., SUITE 200 (202) 234-4433 WASHINGTON, D.C. 20009-4309 www.nealrgross.com
73 NEI.
1 MEMBER PETTI: I think your mics on mute.
2 CHAIR BIER: sorry. Thank you. I got one 3
mic and not the other.
4 Okay. We are now back in session. And 5
ready to hear from Jon Facemire from the Nuclear 6
Energy Institute and then after that we will have 7
public comments from anyone else. Thanks.
8 MR. FACEMIRE: Thank you. And thanks for 9
the opportunity to present today. My name is Jon 10 Facemire. I am a senior project manager in the New 11 Nuclear Group at NEI.
12 A little more on my background. I have 13 been with NEI for about two years. Prior to that I 14 was at X-Energy, where I was a licensing manager and 15 developing our licensing modernization project 16 preliminary safety analysis report. So I have spent 17 most of the last four years thinking about what level 18 of risk information is good enough for construction 19 permit application.
20 Prior to that I was Jensen Hughes 21 supporting the operating fleet, the best informed 22 completion times, 5069, basically any risk-informed 23 application. I worked for Exelon and various clients 24 throughout the industry.
25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1716 14th STREET, N.W., SUITE 200 (202) 234-4433 WASHINGTON, D.C. 20009-4309 www.nealrgross.com
74 I really appreciated the conversation this 1
morning. I do want to have the scenario that was in 2
my mind. If I was a light-water reactor applicant, I 3
would a PRA to give me confidence that the licensing 4
basis event selected in my preliminary safety analysis 5
report were complete, right? That would be my goal.
6 As the staff noted, there is a lot of 7
different potential use cases for the PRA, but that's 8
kind of what I had I mind going in.
9 CHAIR BIER: Jon, can you just pull the 10 mic a little closer. Thanks.
11 MR. FACEMIRE: Sure. How's that? So 12 yeah, a lot of the comments made by Member Bob Martin 13 resonated. They made a lot of sense to me. And that 14 is really the one comment that we did feel was 15 outstanding and needed to be further addressed in the 16 staff guidance.
17 So I will go through the slides. NEI did 18 provide comment on the interim staff guidance. We do 19 appreciate that seven of the nine comments were 20 addressed or partially addressed. Thanks to the NIC 21 for that clarification.
22 But our remaining comments are really 23 focused on consistency with the level of detail 24 required for construction permit PRA information, 25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1716 14th STREET, N.W., SUITE 200 (202) 234-4433 WASHINGTON, D.C. 20009-4309 www.nealrgross.com
75 specifically the guidance that sits in Reg. Guide 1
19.253, Appendix A.
2 We think that it's
- really, really 3
important that the expectation for a light-water 4
reactor and a nonlight-water reactor be similar for 5
what's good enough for a PRA at the CP stage.
6 We also were looking forward a little bit 7
to implementation of the ADVANCE Act implementation, 8
how this guidance could be used down the road for Part 9
- 53. So some of the background we go into -- leans 10 into the guidance in those documents.
11 CHAIR BIER: If you could pause for a 12 moment, apparently some of the people online cannot 13 see the slides. And I doubt that's a problem on your 14 end. But can we get Thomas or somebody to look at 15 that?
16 DR. BLEY: Yeah, I can't see the slides.
17 CHAIR BIER: Okay.
18 MR. PALMTAG: This is Scott, I can see 19 them.
20 MEMBER PETTI: I have had this problem 21 historically so I thought it was just me. But I see 22 others have problems.
23 MR. SNODDERLY: So it sounds like other 24 people can see them. What I would ask Member Petti 25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1716 14th STREET, N.W., SUITE 200 (202) 234-4433 WASHINGTON, D.C. 20009-4309 www.nealrgross.com
76 and Dennis, Consultant Bley, could you please log out 1
and log back in if that would help.
2 MEMBER PETTI: Sure.
3 CHAIR BIER: That usually is the solution.
4 MR. SNODDERLY: Thank you.
5 CHAIR BIER: I think we can go ahead then, 6
and we'll see how that goes.
7 MEMBER MARTIN: I have a question. Now 8
you had this comment on your previous slide looking 9
for consistency for LWRs and non-LWRs. Are you sure 10 that that's what you want?
11 Because I think I can, you know, moving 12 forward in a world where we have, you know, Part 53 13 where we have PRAs kind of leading the design process 14 and that they are the initial basis for those kind of 15 decisions as opposed to Part 50, where it has kind of 16 been led by more deterministic thinking. And PRA, 17 integration of PRA has been more of a confirmatory 18 role. That would seem to apply a different focus in 19 the different domains. And, you know, Part 52, I 20 think is more kind of in the confirmatory realm too, 21 but it is obviously a move towards a greater 22 integration of PRA.
23 It would, to me, be different paths when 24 it comes to, you know, how an agency here would look 25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1716 14th STREET, N.W., SUITE 200 (202) 234-4433 WASHINGTON, D.C. 20009-4309 www.nealrgross.com
77 at that and how an applicant might want the agency to 1
look at it, you know.
2 MR. FACEMIRE: Yeah. So I am making that 3
comment in the context of our broader comments on Part 4
53 that PRA should not have to play a leading role in 5
the licensing of nonlight-water reactors. There are 6
certain applicants who want to pursue a more 7
deterministic maximum hypothetical accident approach.
8 We think that that should be appropriate and that --
9 well, we agree with the staff that the application of 10 the PRA should determine the level of detail needed 11 for the PRA.
12 If you are following LMP, right, back a 13 little bit more. If you are following MHA, then the 14 level of PRA information should be way less.
15 MEMBER MARTIN: Right, right. Then it 16 still becomes kind of a case-by-case --
17 MR. FACEMIRE: Yup.
18 MEMBER MARTIN: -- depending on, you know, 19 claims of graded approach or whatever, which actually 20 kind of complicates it for everybody. But, you know, 21 it's hard to find that one size fits all approach 22 under the realm of being consistent. You know, not an 23 easy task for anybody.
24 MR. FACEMIRE: Understood. All right. So 25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1716 14th STREET, N.W., SUITE 200 (202) 234-4433 WASHINGTON, D.C. 20009-4309 www.nealrgross.com
78 the specific language. And Reg. Guide 1.253 that we 1
feel is quite appropriate and that we want to better 2
align with this interim staff guidance on this page.
3 So, yes, identifying hazards and plan operating 4
states, being comprehensive and systematic. I do 5
think we want to look for areas of concern. And we 6
should disposition them.
7 But they can be dispositioned in a lot of 8
different ways. They can be dispositioned with the 9
PRA. They can be dispositioned with acceptable 10 screening methods or risk-informed supplemental 11 evaluations or crediting design basis hazard levels.
12 Now design basis hazard levels are kind of 13 specifically defined in LMP. But we are trying to 14 interpret that a bit more broadly. We see that as 15 traditional hazard analysis should be acceptable. And 16 in the later slides we get into some of the Part 53 17 language that we think supports that.
18 Page 33 from Reg. Guide 1.253 regarding 19 PRA acceptability, minimum scale at a CP is at power, 20 internal events only. We were happy with the common 21 evolution on that piece of it.
22 But the piece that we feel was not 23 dispositioned fully was the CP applicant may be able 24 to disposition certain hazards by crediting design 25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1716 14th STREET, N.W., SUITE 200 (202) 234-4433 WASHINGTON, D.C. 20009-4309 www.nealrgross.com
79 basis hazard levels in lieu of explicitly modeling 1
these hazards in the PRA.
2 We felt that the PRA guidance and the 3
supplemental evaluation guidance go beyond this 4
statement, which would allow you to use traditional 5
hazard analysis in lieu of a PRA or a supplemental 6
evaluation.
7 I will pause there.
8 MEMBER MARTIN: I will bring up my comment 9
from earlier regarding, you know, what I think would 10 be an objective of any applicant, which would be not, 11 you know, duplicate efforts when it comes to preparing 12 PRAs for environmental report and/or CPA. Did you put 13 much thought into that? Obviously, you mentioned your 14 experience with X-energy. Did that come up in your 15 own experience? And did you bring that to NEI?
16 MR. FACEMIRE: You know, we leveraged the 17 PRA. It was a full power internal events PRA with 18 either supplemental evaluations or deterministic 19 hazard analysis. And those identified are candidates 20 of near accidents that we analyzed for purposes of the 21 environmental report and scanned those.
22 MEMBER MARTIN: Right, right. But you 23 wouldn't necessarily be looking at that for an LWR, 24 you know, situation. It kind of seems -- again, and 25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1716 14th STREET, N.W., SUITE 200 (202) 234-4433 WASHINGTON, D.C. 20009-4309 www.nealrgross.com
80 I am your -- I was the -- I am the X-energy design 1
center lead. So, you know, I am particularly 2
interested in your last four years, but moving towards 3
LWR space.
4 You wouldn't necessarily want to apply 5
that mindset, you know, for new --
6 MR. FACEMIRE: Is that a question of the 7
licensee in my mind?
8 And then the longer one, and this gets 9
into the supplemental risk evaluation guidance. In my 10 mind, this language in Reg. Guide 1.253 pointing back 11 to NUREG 1855 is really sufficient.
12 It kind of gets to the discussion of this 13 morning, right? There are many ways to address the 14 risk triplet, some of them quite conservative. Like 15 one of our very initial buyer screenings at X-energy 16 was assume everything outside of the reactor building 17 burns down at a frequency of one, show that you are 18 still safe even for that very, very conservative 19 scenario and that's it.
20 I don't think that meets the supplemental 21 evaluation guidance because we didn't put a lot of 22 thought into the initiating event scenario there. It 23 was just fill it all. We're still fine.
24 So our concerns are largely about what is 25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1716 14th STREET, N.W., SUITE 200 (202) 234-4433 WASHINGTON, D.C. 20009-4309 www.nealrgross.com
81 the minimum acceptable for the supplemental 1
evaluations for hazards.
2 Some other items, pointing back to the 3
staff requirements memorandum around Part 53, some of 4
the guidance in there, screening tools and bounding 5
are simplified methods may be used for any modes 6
and/or hazards. And the staff should not apply 7
consensus PRA standards as a strict checklist of 8
requirements, again getting back to the idea that 9
deterministic traditional hazard analysis approach in 10 our mind should be appropriate and then would make 11 this interim staff guidance applicable to Part 53 as 12 well.
13 So looking at efficiency, we think there 14 is a potential for this guidance to not just be 15 applicable for the current regulatory pathways 16 available, but could be applicable for Part 53 down 17 the road.
18 And then the Part 53 proposed tool 19 language reflected some of that guidance. So the PRA 20 can be used in combination with generally accepted 21 approaches or systematically evaluating engineered 22 systems. And there is flexibility in determining the 23 degree to which the PRA needs to be developed.
24 I am trying to keep hammering this home.
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82 But I think there is also in a wide range of 1
applications this same concept is coming through. And 2
it is really important for implementation of the 3
ADVANCE Act down the road.
4 So the language in Section 208 for the 5
regulatory requirements for microreactors is that the 6
commission shall develop risk-informed and 7
performance-based strategies and guidance, including 8
strategies and guidance for risk analysis methods, 9
including alternatives to probabilistic risk 10 assessments. Although another opportunity, it doesn't 11 have to be PRA if you can justify it based on bounding 12 risk deterministic methodologies and hazard analysis 13 should be sufficient.
14 CHAIR BIER: A quick question on this Jon.
15 It sounds like the staff has been saying that they are 16 happy to consider alternative methods, but don't want 17 to prescribe specific alternative methods. Is that 18 agreeable with you or do you wish they would go 19 farther?
20 MR. FACEMIRE: So one of my concerns from 21 my experience as an applicant was not knowing what was 22 good enough, particularly for a buyer which has been 23 a point of contention in the past. We wanted to 24 provide enough information that we wouldn't be stuck 25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1716 14th STREET, N.W., SUITE 200 (202) 234-4433 WASHINGTON, D.C. 20009-4309 www.nealrgross.com
83 in regulatory limbo for a very long time. And we 1
didn't feel that we had enough confidence in what was 2
sufficient in that area in particular. But there are 3
others.
4 MEMBER MARTIN: Don't you see -- I mean, 5
the way I see this, you have kind of contradictory 6
objectives. You want all the flexibility, but you 7
want to also have absolute certainty that you provided 8
the right amount of information.
9 It makes, you know, quite a challenge to 10 craft those kind of rules or, you know, expectations.
11 So I'll turn to the staff and go, you know, I can 12 appreciate the challenge you've got when you're trying 13 to do all things in this case, but --
14 MR. FACEMIRE: Yes.
15 MEMBER MARTIN: -- I don't have the job.
16 MR. VASAVADA: This is Shilp from the 17 staff. I was going to say and to add to that, we have 18 to accommodate a broad spectrum of properly designed 19 maturity by licensing applicants. It's more than just 20 focus on the LMP or something like that. There can be 21 different ways of doing it.
22 So trying to be as accommodating as we 23 can, but it is providing the bare minimum to make sure 24 that there is consistency, accuracy and 25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1716 14th STREET, N.W., SUITE 200 (202) 234-4433 WASHINGTON, D.C. 20009-4309 www.nealrgross.com
84 repetitiveness.
1 MEMBER MARTIN: Yeah, I mean, I can 2
appreciate the broad vision, you know, for the role of 3
PRA at different stages of application. But here, of 4
course, we are focused on Part 50 and LWRs and a 5
relatively narrow scope.
6 I just feel like you can kind of -- you 7
can do better than what we have right now and provide 8
meaning and provide a little more flexibility and a 9
little bit more certainty without trying to, you know, 10 take on the whole thing that, you know, maybe a Part 11 53 is trying to do. You know, but I certainly 12 encourage a separation of that long-term vision just 13 for the near-term objective.
14 MR. FACEMIRE: And we'll get to it on one 15 of the last slides. But in this specific context, we 16 are not asking for significant changes. And that 17 Table 2 right now, there is the PRA pathway. There is 18 a supplemental evaluation pathway.
19 And our suggestion, our proposed 20 resolution, is a traditional pathway, right, that if 21 at your CP application you have a deterministic hazard 22 assessment, like do you have a fire safe shutdown 23 analysis, that should be god enough.
24 MR. VASAVADA: I'm sorry. This is Shilp 25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1716 14th STREET, N.W., SUITE 200 (202) 234-4433 WASHINGTON, D.C. 20009-4309 www.nealrgross.com
85 from staff. Can I jump in?
1 MEMBER MARTIN: Sure.
2 MR. VASAVADA: So I wanted to kind of go 3
back and redirect what Stacey had said during the 4
presentation. I used ideas from the staff in cases 5
where the applicant chooses to provide that type of 6
risk assessment information.
7 If an applicant chooses to do it 8
differently, deterministically, then a lot of this 9
would not be something that the staff would want to 10 look at in the PSAR. We would be looking on the PSAR.
11 So I just wanted to also make that scoop of the ISG 12 clear.
13 It's if f the applicant chooses to provide 14 certain diagnostic information. It is not meant to be 15 like the replacement for Reg. Guide 1.17.
16 MR. FACEMIRE: So going forward, I'm not 17 going to go through all the comments for the most 18 part. We were relatively happy with how they were 19 addressed. The one that we felt was not addressed 20 that was specifically around those hazard evaluations.
21 We felt that the supplemental evaluations are asking 22 for more.
23 And, you know, so leaning into the 1.253 24 language, our outstanding issues both for hazard 25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1716 14th STREET, N.W., SUITE 200 (202) 234-4433 WASHINGTON, D.C. 20009-4309 www.nealrgross.com
86 assessment and for low power shutdown risk, we didn't 1
feel like the guidance for supplemental evaluations go 2
beyond what should be required at the CP stage.
3 As you all have said, we understand this 4
guidance was for those who choose to provide that 5
piece of information. But one thing that wasn't 6
clear, like, what we had envisioned was that there 7
might be situations where you want to provide that 8
full power internal events PRA, right? In my mind, 9
that makes a lot of sense. You can do it very early 10 based on the design maturity that you have. You can 11 meet most of the elements.
12 And our interpretation, and it sounds like 13 this was wrong, was that if we provided that internal 14 events PRA information, then we would need to also 15 provide the supplemental evaluations for the other 16 hazards in the lower modes. If that was not the 17 intent, and it sounds like it wasn't, maybe we misread 18 that.
19 But from a human factors perspective, like 20 those Tables 1 and 2 certainly implied that in our 21 reading of it. And some clarity that that was not the 22 intent would be appreciated.
23 But our suggestion was just to put a third 24 column in the table that says traditional analysis, 25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1716 14th STREET, N.W., SUITE 200 (202) 234-4433 WASHINGTON, D.C. 20009-4309 www.nealrgross.com
87 traditional hazard analysis, traditional lower modes 1
and a qualitative assessment, we thought that provided 2
clarity. I do acknowledge there is multiple ways to 3
do that. And that was the end of my slide outside of 4
5 CHAIR BIER: I guess on that last point, 6
and following up on staff that if somebody is doing a 7
traditional deterministic type analysis, staff would 8
not be using this ISP, I guess the issue might be if 9
somebody wants to do traditional deterministic on some 10 hazards and maybe PRA on other hazards may be why it 11 would be worth having it in the tables. Just a 12 thought. Is that kind of where you are headed, Jon?
13 MR. FACEMIRE: Yeah, or the Reg. Guide 14 1.70 guidance is quite old.
15 CHAIR BIER: Okay.
16 MR. FACEMIRE: I am looking for somewhere 17 to tell us what's good enough for a CP given how the 18 regulations have evolved over the years. And I saw an 19 opportunity in this interim staff guidance. But I 20 understand the scope as discussed this morning.
21 CHAIR BIER: Okay. Do we have further 22 questions or comments for Jon now that you have 23 completed your presentation?
24 MEMBER MARTIN:
Maybe just one 25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1716 14th STREET, N.W., SUITE 200 (202) 234-4433 WASHINGTON, D.C. 20009-4309 www.nealrgross.com
88 clarification. Maybe, you know, pull the staff back 1
in. Reg. Guide 1.253, I didn't see it in the ISG.
2 I'm looking at the staff. What's your feeling about 3
Jon's comments relating to more integration of that 4
Reg. Guide here?
5 MR. VASAVADA: And so as Stacey talked 6
about in the presentation, we had great representation 7
from a group that --
8 CHAIR BIER: Yeah, Shilp can you pull your 9
mic closer? Thank you.
10 MR. VASAVADA: I will start again. So we 11 had great representation in the working group from the 12 folks who are already closely tied to Reg. Guide -- or 13 Draft Guide 1.253.
14 And we brought a lot of the concepts that 15 we could, recognizing the defense in the scope. That 16 one is focused, and if I am understanding correctly, 17 primarily on LMP. So there's like a set, you could 18 say. You know when the PRA is going to be useful and 19 how it is going to be used.
20 There is a lot of body of evidence over 21 there to support that. Over here, again as I said, it 22 is a much broader spectrum. I am not going to say a 23 majority but also what it is going to be used for in 24 there and different places.
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89 So to the extent that we could, we were 1
able to bring in all the elements, or the necessary 2
elements of, especially the minimum needs of the PRA 3
for all events and the others. It pretty much mimics 4
1.253 because we caught that information from those 5
folks, and we thought it would be applicable LWRs.
6 So the short answer is, to the extent that 7
we could, we brought those elements in. But we do 8
recognize the defense in the scope that we were trying 9
to help staff achieve. But this guidance for LWRs 10 compared to what was in Draft Guide 1.253, which is 11 where some of the defenses exist.
12 MEMBER MARTIN: Yeah, I would certainly 13 agree with this. You don't want to hold LWRs to a 14 higher standard, particularly when you are in hazard 15 risk evaluation. You know, to an earlier point about 16 delta reviews, that is really how you -- you know, an 17 applicant or how I see an applicant using, you know, 18 or being informed by this ISG, which is to say, you 19 know, more properly.
20 Again that has kind of been my biggest 21 concern is trying to find the balance and, you know, 22 it all comes down to kind of case-by-case and how the 23 applicant -- and I don't know if there is really much 24 we can do outside of that. But very difficult to 25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1716 14th STREET, N.W., SUITE 200 (202) 234-4433 WASHINGTON, D.C. 20009-4309 www.nealrgross.com
90 provide the clarity and the flexibility at the same 1
time.
2 One thought is, you know, to the staff's 3
comment, here, you know a second ago, the range of 4
maturity -- I'm not getting -- in the interest of 5
simplifying and providing more clarity, can we make an 6
assumption at the construction permit stage? And, you 7
know, it is 10 to 20 percent complete. And then, you 8
know, kind of craft guidances on assumption that you 9
don't have that maturity. And, you know, you're not 10 trying to do more than necessary.
11 I know, again, Stacey mentioned, you know 12
-- or maybe you did, too. But the finality, you know, 13 there might be some aspect of the design that 14 applicant feels they can get some finality. But not 15
-- maybe that just doesn't get handled at the 16 construction permit. It's just, you know, carved out 17 for a longer term, a consideration.
18 But focusing strictly on CP, I think you 19 could just eliminate the maturity question and just 20 accept that it is only going to be, you know, 10 to 20 21 percent mature. And that there is a certain freedom 22 that comes with that at that point. I understand the 23 next piece.
24 MR. PHAN: May I?
25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1716 14th STREET, N.W., SUITE 200 (202) 234-4433 WASHINGTON, D.C. 20009-4309 www.nealrgross.com
91 MEMBER MARTIN: Underneath the mic over 1
there.
2 MR. PHAN: So this is Hahn Phan. I am the 3
senior PRA analyst.
4 In the past I left many application for 5
non -- for AWRs, for AWRs, for Part 2 application. In 6
this interim staff guidance there are inconsistencies 7
with the elements included in the interim staff 8
guidance.
9 Personally, based on my experience and 10 information submitted to the NRC in the past for 11 whenever there are sufficient information data in 12 model that the applicants, under their rules, their 13 expectation, they could come up to the PRA standard 14 threshold. Most of these applications include low 15 power shutdown. Right now under the transformation, 16 there is no requirement of PRA under Part 2.
17 So that is up to the applicants. But for 18 the staff, after the application, as far as public 19 confidence in the application is the applicant 20 understand rules they can come up with a model of the 21 PRA that will start the insights for low power and 22 shut down and other actions if they are willing to do 23 so. So why we have included that there? Because that 24 is there if they want to. Thank you.
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92 MEMBER MARTIN: Thank you.
1 MR. FACEMIRE: Just on the conversation a 2
little more. My experience was at a CP stage, you 3
don't have cable tracing. Very, very hard to do a PRA 4
without cable tracing. You don't have all the pipe 5
layouts yet. Very hard to do an internal flood PRA 6
without pipe.
7 You don't have operating procedures. It 8
is very hard to meet the HRA elements without 9
operating procedures. So those could be some pieces 10 where examples like, I pulled up during the meeting HR 11 E.1, I called that operating procedures explicitly.
12 Like just an example that it is fine that some things 13 are not applicable and not a capability category one, 14 I think, would be very useful to give applicants 15 assurance that they are not going to get in trouble 16 for meeting a standard that is impossible for them to 17 meet at this stage.
18 I do understand and I appreciate that it 19 is in words that exam itself.
20 CHAIR BIER: You may also not have 21 equipment elevation. So it would be difficult to do 22 external flooding. Other questions or comments before 23 we turn to public comments?
24 Okay. So I know that --
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93 MEMBER PETTI: There's a hand.
1 CHAIR BIER: Yes, I know we have a public 2
comment waiting from Bob Budnitz, if you want to go 3
ahead now?
4 MR. BUDNITZ: Can you hear me?
5 CHAIR BIER: Absolutely.
6 MR. BUDNITZ: This is Bob Budnitz. I am 7
in Berkeley. I want to talk about seismic margins 8
methods. If you go back to the NRC slides, and you 9
don't have to do it. But there are two tables that 10 are taken from the Draft Reg. Guide. The one table 11 about the one table about the elements of an internal 12 events PRA and then the second table talks about 13 external hazards, various kinds of hazards. And 14 alternative, it uses the phrase alternative risk 15 evaluation methods for those.
16 And under seismic in that table it says 17 either a seismic PRA or a seismic margin analysis.
18 And in other words, at the CP stage, according to the 19 Reg. Guide, a seismic margin analysis would be an 20 adequate way of understanding the risk -- to aid in 21 decision-making, whether it is acceptable or not.
22 And I want to make a point about seismic 23 margins analysis that I hope everybody understands, 24 which is that the seismic margin analysis does not 25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1716 14th STREET, N.W., SUITE 200 (202) 234-4433 WASHINGTON, D.C. 20009-4309 www.nealrgross.com
94 produce what we traditionally think of as a risk 1
estimate. It is not a risk estimate.
2 By the way, core damage frequency is 3
directly related to risk, although it is not a risk 4
estimate either. But what the seismic margin analysis 5
method produces is for an individual component, it 6
produces what we call a HCLPF capacity, H-C-L-P-F, a 7
high confidence, low probability failure capacity for 8
a component. And if a cut set has four components, it 9
produces a HCLPF capacity for the cut set, for a 10 sequence.
11 And if you roll those together, you can 12 come up with a HCLPF capacity for the plant as a 13 whole. But that HCLPF capacity is only related to the 14 risk if you know something about the hazard.
15 Let's suppose that the plant level HCLPF 16 capacity is.5g. I just made that up. Well, that's 17 a very different risk in the West than it is in New 18 England. And it is very different in New England than 19 it is in Florida because the seismic hazard is so much 20 different by large factors between those different 21 areas of the country.
22 So the notion that the seismic margin 23 assessment is a risk evaluation is in my view, well, 24 it's a little dicey. It can only be a risk evaluation 25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1716 14th STREET, N.W., SUITE 200 (202) 234-4433 WASHINGTON, D.C. 20009-4309 www.nealrgross.com
95 if you know something at least about the hazard, the 1
seismic hazard, at the site so that you can do a rough 2
convolution and understand what the real risk actually 3
is.
4 And I am making that point because you 5
shouldn't be misled to think that a seismic margin 6
assessment, as useful as it is, is by itself a risk 7
evaluation.
8 On the other hand, if it is a CP, you have 9
a site. You might not know the seismic hazard as well 10 as you really would like at the end. But you know 11 something about the hazard for sure because we know 12 something about the hazard in every site in the U.S.
13 And therefore, you can get your arms 14 around it, But I just want to make that point. It is 15 a very simple point.
16 CHAIR BIER: Okay. Thank you very much, 17 Bob.
18 MR. PHAN: Hello, Dr. Budnitz. This is 19 Hahn Phan, NRC.
20 MR. BUDNITZ: Hi, Hahn.
21 MR. PHAN: Hello. In response to your 22 position. According to the SRM, on the SECY-93-087, 23 the staff not reviews these assignment margin 24 assessments. The staff focus on the PRA-based 25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1716 14th STREET, N.W., SUITE 200 (202) 234-4433 WASHINGTON, D.C. 20009-4309 www.nealrgross.com
96 estimate which the models place on the internal 1
defense PRA. And that gives us insight. It rarely 2
went to the risk not just the -- in a success path or 3
any of the deterministic. But the staff get risk 4
insight from the PRA-based estimate. And we expect 5
applicant to address assignment using that 6
methodology. Thank you.
7 MR. BUDNITZ: By the way, Hahn, I 8
completely agree. There are very important insights.
9 The point I was making was that those important 10 insights should not be considered as -- they are not 11 by themselves a risk estimate, even though the table 12 calls them a risk estimate. It is not as close as 13 surrogate as CBF is to risk. Okay?
14 And just to make a point for some people 15 on the call that don't know, a seismic margin method 16 was invented in 1984 by an expert panel that I 17 chaired. And if you think that was 40 years ago, you 18 are off by one. So it's been around.
19 We were there at the time trying to do 20 something to get our arms around a surrogate for risk, 21 by the HCLPF capacity is a very useful, but certainly 22 not a direct surrogate for risk. Okay?
23 CHAIR BIER: Thank you. Any follow-up 24 after Bob's comment? I appreciate you providing that.
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97 Are there any other public comments either 1
in the room or online, on the phone? If you are 2
online, you can raise your hand. If you are on the 3
phone, I guess you can just unmute and introduce 4
yourselves.
5 MEMBER MARTIN: Is that still Bob's hand?
6 CHAIR BIER: I think that's still Bob's 7
from before. So I think we've heard from him. If 8
there is no further public comment, then we should 9
take at least a few moments for committee discussion 10 to see how we want to proceed on this topic.
11 My own sense, which members are happy to 12 disagree with if they want, my own sense is this does 13 not require a letter because really most of the impact 14 of this is commercial, not safety-related.
15 But if there are safety problems, we have 16 the whole OL process that will hopefully capture that 17 with much more detailed PRA information and that at 18 the CP stages, there are issues first of all of just 19 licensee liability of going forth with the CP approval 20 that then may not receive an OL if some of the 21 justifications are not there. Or, as Jon as 22 mentioning now of, you know, just the regulatory of 23 limbo of you provided what you thought was good enough 24 and then I turns out it wasn't good enough, and there 25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1716 14th STREET, N.W., SUITE 200 (202) 234-4433 WASHINGTON, D.C. 20009-4309 www.nealrgross.com
98 is an iteration of getting the CP approval.
1
- But, you
- know, while I
think the 2
discussion here has highlighted a lot of good insights 3
that hopefully the staff will take away, I don't know 4
that any of them rises to the level that I would see 5
as writing a letter on.
6 But if anybody else on the committee wants 7
to comment on that, either to, you know, state a 8
reason why a letter might be needed or even just 9
stating some points that you hope will show up in the 10 meeting summary, I am happy to hear those.
11 MEMBER MARTIN: Vicki, I will support --
12 I tried to highlight a couple, you know, issues that 13 I had. You're the lead on this. And obviously I am 14 going to follow your lead. Ultimately this is staff 15 guidance. Something they are preparing for themselves.
16 And, you know, I appreciate after hearing 17 from NEI and, of course, the staffers that, you know 18 they are trying to do lots of -- you know, solve lots 19 of different problems.
20 I guess if there was one thing that, you 21 know, I wanted to reiterate, was I think there is 22 importance of being consistent with how PRAs are being 23 prepared or to complete this level. It is expected 24 that PRAs are being prepared for the environmental 25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1716 14th STREET, N.W., SUITE 200 (202) 234-4433 WASHINGTON, D.C. 20009-4309 www.nealrgross.com
99 report. You would want to consistency there. But 1
again, that's on the applicant side.
2 But ultimately, any applicant, you know, 3
that pursues these kind of activities needs a very 4
good, you know, regulatory affairs manager, licensing 5
managers. And experienced ones know how to navigate 6
and know how to, you know, provide the right 7
information to control the conversation.
8 So ultimately it maybe doesn't rise to 9
anything more than, you know, a nod in this meeting.
10 But hopefully we have provided some useful discussion 11 and a couple points for later consideration.
12 CHAIR BIER: Yeah. In my mind the only 13 point that was discussed that might have risen to the 14 level of a letter was a question I asked about if 15 somebody comes in with a CP level PRA and gets it 16
- blessed, does that satisfy the requirement 17 automatically of an OL PRA, in which case I would be 18 very worried.
19 But since everybody has the opportunity to 20 come back and take another look, staff and ACRS and 21 everybody else at the OL stage, I think the safety 22 implications are not a huge deal that we need to 23 comment on.
24 Any further discussion?
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100 MR. SNODDERLY: I got Walt.
1 CHAIR BIER: Oh, Walter. Thank you. You 2
want to go ahead?
3 MEMBER KIRCHNER: Thank you, Vicki. Bob 4
Budnitz brought up a good point. It started me 5
thinking about things. We have been talking rather 6
loosely about level of maturity of design, and we use 7
numbers that are, I think -- based on lessons from the 8
past, we probably would expect a much higher percent 9
complete design than 10 or 20 percent.
10 But what comes to mind is that the 11 applicant, and I am looking at 10 CFR 5035, the 12 applicant may request as part of a design -- a 13 construction permit application some specific 14 approval.
15 And I think early on, if you're actually, 16 you know, building and pouring concrete and rebar for 17 a facility -- I'm thinking of the containment 18 structure for an LWR, whether it is a conventional one 19 or an advanced containment design that we've seen some 20
-- you would want probably at the construction permit 21 time frame approval of that particular aspect of the 22 design. And that probably requires a fairly 23 sophisticated seismic analysis for the site with the 24 site specific grand motion spectrum, et cetera, et 25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1716 14th STREET, N.W., SUITE 200 (202) 234-4433 WASHINGTON, D.C. 20009-4309 www.nealrgross.com
101 cetera, and all that.
1 I guess my concern here -- an applicant 2
can do that. But an applicant also choose to use 3
this PRA approach, does that become a trap? I mean, 4
the PRA, the ISG pretty much follows an outline for a 5
very complete PRA. What level of PRA will be 6
acceptable?
7 I think the comments from NEI we were 8
thinking through -- my concern is just that an 9
applicant might get in a position where they are in a 10 kind of a do loop with the staff on what's acceptable.
11 I would think, of course, an applicant can 12 go ahead at risk with construction, but he would 13 probably want some finality on certain design aspects 14 of the plant, like say a containment structure.
15 And I am just wondering if they are also 16 using PRA, what level of PRA is needed to get that 17 design approval? Do you see my concern, Vicki? My 18 concern is that the expectation or the requirement for 19 completeness of a PRA, say a seismic PRA, may be 20 difficult to do early on.
21 But can they -- if an applicant -- this is 22 hypothetical. If an applicant submits a PRA as part 23 of their construction permit application -- it is not 24 required -- but they choose to go this option and then 25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1716 14th STREET, N.W., SUITE 200 (202) 234-4433 WASHINGTON, D.C. 20009-4309 www.nealrgross.com
102 the staff uses their ISG, is there a potential for 1
getting into a do loop so to speak between the staff 2
and the applicant on satisfying the requirements?
3 I mean, just the staff will have the ISG.
4 It is pretty complete, very thorough. How does the 5
staff and the applicant negotiate say that just a 6
level one full power internal events PRA is sufficient 7
and then use other methods, like suggested in the last 8
NEI slide here, Item 3, to fill out the rest of the 9
requirements for the application? Is that flexibility 10 going to be there or is the expectation one, that it 11 is completely satisfied by the PRA and all the 12 requirements that seem to appear in the ISG?
13 CHAIR BIER: Does the staff --
14 MEMBER KIRCHNER: Is there a graded 15 approach? Is there a way that is -- that's my 16 concern. I will stop there.
17 CHAIR BIER: Does the staff want to 18 respond on that?
19 MR. VASAVADA: Yeah, Shilp Vasavada from 20 the staff. I will respond. I think the short answer 21 to Member Kirchner's question is yes.
22 First of all the question is whether 23 somebody wants to rely on a PRA or choose to provide 24 a PRA to support a CP application? If not does, the 25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1716 14th STREET, N.W., SUITE 200 (202) 234-4433 WASHINGTON, D.C. 20009-4309 www.nealrgross.com
103 ISG actually doesn't apply?
1 And as we talked about, stated, clarified 2
and talked about during the presentation, and we had 3
a discussion with -- Mr. Facemire's presentation.
4 Even ISG says internal events PRA something, if you 5
want to support your application you can -- a PRA is 6
something you can look for. Everything else you can 7
choose either a PRA or a non-PRA based risk 8
evaluation.
9 We also talked about not do it for certain 10 cases and do a deterministic evaluation. So, again, 11 the short answer is yes. I don't think that ISG is 12 prescribing anything, either to the staff or to the 13 applicant.
14 There are so many different combinations, 15 I
could literally that it is I
think 16 counterproductive in our view to say this is the 17 minimum we will need for all these different scenarios 18 because it is very likely we will miss a scenario. So 19 that is physically our take on the staff's side.
20 CHAIR BIER: I do see your point, Walt, 21 that a pretty good seismic characterization would be 22 needed in order to have a containment design, which is 23 going to survive an earthquake. On the other hand, as 24 Jon was mentioning, we may not know pipe routings and 25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1716 14th STREET, N.W., SUITE 200 (202) 234-4433 WASHINGTON, D.C. 20009-4309 www.nealrgross.com
104 pipe hangers and all the rest of it to do a detailed 1
seismic analysis in the PRA. Jon, do you want to 2
expand?
3 MR. FACEMIRE: Yeah, I just want to add 4
that next month on the 25th, the ACRS is meeting again 5
to discuss Reg. Guide 1.251, which lays out different 6
options, traditional, more LMP focused, and an option 7
three that needs more exploration in my mind.
8 CHAIR BIER: Yeah.
9 MEMBER KIRCHNER: Vicki, can I pursue this 10 a little further?
11 CHAIR BIER: Please.
12 MEMBER KIRCHNER: One of the things that 13 happened in DOE projects was that they would commence 14 construction and then later seismic analysis would 15 indicate that the structure wasn't going to be 16 qualified for the demand. And so it's very expensive 17 to then start redoing a construction project starting 18 with the footings and the, you know, concrete and 19 rebar and all the rest.
20 So it would seem to me at the construction 21 permit stage, one would want to get some design 22 approval on certain things like containment. And, 23 yes, you probably cannot do the complete seismic PRA 24 at that point because of all the design details and 25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1716 14th STREET, N.W., SUITE 200 (202) 234-4433 WASHINGTON, D.C. 20009-4309 www.nealrgross.com
105 such that aren't necessarily available.
1 But one would hope not to have to go back 2
and redo a design, say of something as important as 3
the containment. So I'm just concerned. Maybe it is 4
not a legitimate concern. But I am concerned that you 5
go down this route, and you can't get closure with the 6
staff on certain aspects of the design.
7 The applicant goes ahead at his or her own 8
risk with major construction and then down the road 9
when the PRA is completed at the OL stage then issues 10 may arise.
11 So how do you get, you know, approvals of 12 important aspects of the design early at this 13 construction permit stage and some certainty that down 14 the road that you are not going to find oneself in a 15 situation where that design approval changes?
16 Maybe it's more -- maybe it's not a PRA 17 issue. Maybe it's more just an issue of design 18 maturity at the CP stage and how much risk an 19 applicant is willing to take.
20 CHAIR BIER: And staff is there a response 21 or just --
22 MEMBER KIRCHNER: No, I don't need a 23 response. It's just a concern I have with the CP 24 application.
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106 CHAIR BIER: Okay.
1 MEMBER PETTI: This is Dave.
2 CHAIR BIER: Okay. Yeah.
3 MEMBER PETTI: Walt, this is Dave.
4 Wouldn't the seismic management approach be 5
sufficient?
6 MEMBER KIRCHNER: I would think so.
7 That's what I would hope.
8 MEMBER DIMITRIJEVIC: Vicki?
9 CHAIR BIER: Yeah, Vesna, go ahead.
10 MEMBER DIMITRIJEVIC: I just want to 11 comment on something. In the design certification, 12 this information which we said wasn't available in CP 13 is not available in design certification either.
14 Pipeline is not laid out. Cables are not laid out.
15 Components are not put into place. We don't know 16 elevations. The operating procedures are not 17 available.
18 So there is no difference in design 19 certification phase in CP on these elements which have 20 been here specifically brought up.
21 So I just want to say the only difference 22 when it comes to the seismic is actually in CP we know 23 the location.
24 MEMBER KIRCHNER: Correct.
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107 MEMBER DIMITRIJEVIC: So therefore, you 1
know, we have really to see when we are doing these 2
design certification and the directions we follow 3
there and then, you know, going to the CP. The 4
trouble is more in the CP mode is that not in these 5
parts of design which are not available until like, 6
you know, the late, call it, stage.
7 In CP we don't have a complete design in 8
the sense that we have, you know, design of the 9
systems, the number of the pumps, the valves, things 10 like that. I mean, this side of things are not 11 available in design certification state so the same 12 logic applies to this. I just wanted to bring this up 13 so.
14 CHAIR BIER: Thank you for that comment.
15 And now, Hahn, if you want to proceed?
16 MR. PHAN: In response to your first 17 concern regarding the staff perspective, applicant's 18 perspective, regarding the PRA.
19 In the licensing applications, if there is 20 a section discussing PRA or providing PRA information, 21 the staff will ask for the clarification of this. Why 22 the PRA is sufficient to support the application?
23 In addition to that, if the application 24 includes any use of the
- PRA, including the 25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1716 14th STREET, N.W., SUITE 200 (202) 234-4433 WASHINGTON, D.C. 20009-4309 www.nealrgross.com
108 environmental details or, you know, human engineering 1
factor engineerings, physical security or touch back, 2
then the staff will use the interim staff guidance to 3
ask applicants to clarify why their PRA is sufficient 4
for the risk-informed decision-making to support those 5
application. And that is the purpose of the interim 6
staff guidance. Thank you.
7 CHAIR BIER: Okay. One other comment I 8
wanted to make both for Jon's benefit and maybe 9
anybody else online. As of at least the last I have 10 heard, there is a possibility that the June seismic 11 meeting may be postponed. And I don't know if any of 12 the staff knows any update on that.
13 So don't buy any nonrefundable plane 14 tickets if you want to be here for that meeting. But 15 other than that, it looks like there is a subsequent 16 comment from Bob Budnitz again if you want to proceed.
17 MR. BUDNITZ: Vicki, can you hear me?
18 CHAIR BIER: Yup.
19 MR. BUDNITZ: This is simple enough. Part 20 52 is, of course, the design certification process.
21 In the context of the policy development for Part 52, 22 and this is more than 20 years ago, the commission 23 allowed using the seismic margin method for evaluation 24 of the adequacy of a design certified plan, provided 25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1716 14th STREET, N.W., SUITE 200 (202) 234-4433 WASHINGTON, D.C. 20009-4309 www.nealrgross.com
109 that in the end the plant level HCLPF capacity was 1
1.67 times the design basis.
2 Now I will just tell you how that came 3
about. All of the original early design certification 4
vendors -- we're talking about General Electric and 5
Westinghouse and Combustion -- they were all using.3g 6
as the standard plan for Part 52 purposes for their 7
designs.
8 And then the commission, based on staff 9
input, looked at that and said, you know, if the plant 10 level HCLPF was.5g, remember the design was.3, then 11 that would be adequate. And that's where the 1.67 12 came from. It's the ratio of.5 to.3.
13 And so it is now in policy for Part 52 14 that if you have a design certification and you can 15 show that the plant level HCLPF is 1.67 times the 16 design, which is as I said, if it's.3 then it's.5.
17 Then that is adequately safe.
18 Now you can use that same logic here. You 19 see when they were design -- when a vendor was doing 20 that design, they didn't want to have a continuous 21 structure that was anything close to the 1.67. They 22 better have quite a lot of margin. And everybody put 23 in a lot of margin for the things that they had to 24 commit to early on, like the containment. And other 25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1716 14th STREET, N.W., SUITE 200 (202) 234-4433 WASHINGTON, D.C. 20009-4309 www.nealrgross.com
110 stuff may be addressed later.
1 So it worked out perfectly fine. That is 2
everybody was able to do their design, meet the 1.67 3
with lots of margin, no problem at all. And they 4
could proceed.
5 Now here we are with the same problem 6
here. This is now Part 50, but we are talking about 7
an early design. It really isn't a problem to design 8
the containment, to have way more margin. In fact, if 9
it doesn't it is not going to be doing the 10 containment's job, if you know what I mean?
11 The containment's job at first is to 12 contain, you know, radioactivity, under pressure and 13 stuff like that. So that isn't really a problem. And 14 I don't think the thing that Walt raised, as important 15 as it is, is in practice going to be a constraint on 16 any of the early CP of designers.
17 CHAIR BIER: Okay. Thank you. Any 18 further discussion from committee members or 19 consultant?
20 MR. SNODDERLY: This is Mike Snodderly of 21 the ACRS staff. So I believe -- I just wanted to 22 confirm. So right now your plan, it would be to at 23 the PNP in June to write a summary report which would 24 include some of these insights.
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111 CHAIR BIER: Correct.
1 MR. SNODDERLY: Okay. Thank you. I'll 2
work with you to put something together.
3 CHAIR BIER: Thank you. So I think with 4
that, we are ready to adjourn this morning's meeting.
5 And there is a related, but separate meeting, that 6
will start this afternoon at 1:00 p.m. Thank you, 7
everybody.
8 (Whereupon, the above-entitled matter went 9
off the record at 11:20 a.m.)
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Draft DRA-ISG-2024-XX, Content of Risk Assessment and Severe Accident Information in Light-Water Power Reactor Construction Permit Applications NRC Staff Presentation to ACRS May 21, 2025
Introductions
- Malcolm Patterson, NRR/DRA
- Keith Tetter, NRR/DRA
- Marie Pohida, NRR/DRA
- Steven Alferink, NRR/DRA
- Marty Stutzke, NRR/DANU
- Jeffery Wood, RES/DRA
- Anders Gilbertson, NRR/DANU
- Hanh Phan, NRR/DANU Presenting Staff Contributing Staff India Banks Project Manager, NRR/DNRL Stacey Rosenberg Co-author, NRR/DRA Alissa Neuhausen Co-author, NRR/DRA
Need for the Effort
- Planned use of 10 CFR Part 50 from near-term applicants
- Staff identified a gap in available regulatory guidance for risk insights and severe accident information in LWR CP applications
- No construction permit applications for nearly 40 years
- Past construction permit applications pre-dated agencys key PRA-related actions
- Three Mile Island Action Plan
- Commissions Policy Statements on Severe Accidents and PRA
- Use of PRA at the design stage
Overview This ISG clarifies the scope and depth of the staff review of the description of risk assessment and severe accident information in the PSAR
- SRM-SECY-22-0052:
- Operating license applicants required to submit a description of the plant-specific PRA and its results
- Construction permit applicants are not required to submit a description of the plant-specific PRA and its results
- Many designers of new LWRs are using risk assessment to support risk-informed design decisions
Objective of the Guidance
- Scope of information for risk insights and severe accident information in an LWR CPA commensurate with:
- Design readiness at time of CPA submission
- Use of risk insights and information in CPA (e.g., identifying licensing basis events)
- Overcome misconception that construction permit applicants must meet endorsed PRA standards
Development Approach Information sources such as:
Regulatory Guide 1.70 Regulatory Guide 1.200 Standard Review Plan for Chapter 19 DC/COL-ISG-028 DNRL-ISG-22-001 Internal deliberations
+
Collaboration with non-LWR efforts Determine scope of information to support staff review and findings Guidance document Staff initiated public meetings Design-specific pre-application meetings
Internal Collaboration and External Outreach
- Conducted three public meetings (March & July 2023, January 2024)
- About 40 people participated in each meeting, including new LWR designers
- External stakeholders voiced support for this guidance at the first meeting
- Staff addressed stakeholder feedback on guidance topics
- Advanced reactor staff and new reactor licensing staff contributed to the development of white paper
- Open communication and sharing of similarities or differences in efforts
- Leveraged work on DG-1404, Revision 1 (proposed new RG 1.253)
Applicability
- Considers the role of risk assessment and severe accident analysis at time an application is submitted
- Scope and technical acceptability of CP application PRA depend on intended use of information and level of design maturity
Guidance Content - PSAR Information
- Considers design description requirements in 10 CFR 50.34
- Guidelines are presented as bulleted list for each topic
- To assist PSAR preparation, it can be used as a checklist
- Information identified for inclusion in PSAR is primarily
- descriptions, including justifications
- identification of assumptions and limitations
- summary of results and risk insights
- Level of detail is not prescribed to accommodate variation in design maturity
Scope - Internal Events
Scope - Hazards
Technical Elements
- DC/COL-ISG-028 provides staff positions and clarifications on supporting requirements in (ASME/ANS) RA-Sa-2009 (PRA Standard) that are not applicable or cannot be achieved as written for the DC and COL application stages
- Staff considers this as an approach for a CP application
- For the CP application, consistent with DC/COL-ISG-028, Capability Category I of an NRC-endorsed PRA standard is acceptable for PRAs
Seismic - PRA or Alternative Risk Evaluation
- Applicant can use site-specific response spectra
- Identification of site-specific seismic-induced initiating events (e.g., slope stability, liquefaction, dam failure)
- Applicant can use design response spectra representative of an envelope of multiple sites
- Demonstration that the site is bounded by the design response spectrum
- Applicant can use a seismic PRA
- Description of probabilistic seismic hazard analysis performed to develop the site-specific seismic hazard curves and any changes to the seismic hazard curves used in the seismic PRA
- Identification of site-specific seismic-induced initiating events
Guidance Content - Non-Seismic Hazards 14 Conservative Estimate of Risk Screen hazard from assessment Can hazard be screened on site-specific basis*?
- Re-evaluate at OL stage to account for design changes during construction.
Low Power and Shutdown
- A low-power and shutdown (LPSD) PRA or an alternative risk evaluation is acceptable for a CP application
- Description of any analysis performed to screen POSs from inclusion in the LPSD PRA, including identification of any design features relied on for the screening
Self-Assessment/Peer Review
- PRA self-assessment is acceptable for assessing the technical adequacy
- Certain PRA elements may not be applicable or met at this stage
- PSAR to include:
- Description of PRA self-assessment
- Summary of any limitations arising from maturity of the design
- Staff would accept peer review in accordance with RG 1.200 (would provide additional confidence in PRA results)
Configuration Control Configuration control program information provides confidence in the applicants ability to track assumptions and changes, including:
- identification of PRA technical elements (RG 1.200) that are not met or not applicable, an explanation for the reason for each
- a description of the process to track assumptions and monitor inputs
- a description of how new information will be collected and included consistent with the as-built, as-to-be-operated plant design
Severe Accidents PSAR should include:
- a description and analysis of design features for the prevention and mitigation of severe accidents
- a description of improvements to plant design, operations, or maintenance that prevent or reduce the possibility, likelihood, or consequence of the identified severe accident
RTNSS
- The RTNSS process applies to those non-safety-related SSCs (in designs with passive safety systems) that perform risk-significant functions and, therefore, are candidates for regulatory oversight
- A RTNSS evaluation is not required at CP application stage
- An applicant may choose to provide a RTNSS evaluation at CP application
Public Comments and Resolution Twelve comments received (9 from NEI and 3 from NuScale)
- Staff agreed with 5 comments and made changes to the ISG
- NRC-2024-0217-DRAFT-0001-1/2/6/7
- NRC-2024-0217-DRAFT-0002-3
- Staff partially agreed with 3 comments and made changes to the ISG
- NRC-2024-0217-DRAFT-0001-3/8/9
- Staff disagreed with 4 comments and made no changes to the ISG
- NRC-2024-0217-DRAFT-0001-4/5
- NRC-2024-0217-DRAFT-0002-1/2
Changes to Address Public Comments (1/7)
- Two comments requested additional clarity on the guidance document
- Acceptability of the descriptions of PRA information or the PRA model information and results provided in the PSAR
- Information required to be in the PSAR or available in separate source documents and analyses supporting the CPA
- The draft ISG provides guidance on the PRA information required for a construction permit application (CPA) submittal if PRA information is used in the submittal
Changes to Address Public Comments (2/7)
- Five comments requested clarity or adjustments to the minimum elements and scope of the PRA
- Some elements may not be available
- Discussion of intermediate preliminary results may not be appropriate
- Use of PRA should not be required to determine licensing-basis events
- Not appropriate for this ISG to suggest that hazard risk evaluations are required
- Staff modified the ISG to state that staff should review the applicants justification that the scope and level of detail of any PRA or alternative risk evaluation are consistent with the intended uses of the information... The staff should review the applicants plan for assessing any risk contributors not addressed by a PRA or alternative risk evaluation
Changes to Address Public Comments (3/7)
- One comment stated that the hazard assessment requirements appear to go beyond traditional design requirements for SR SSCs
- This draft ISG does not provide guidance on design requirements or propose alternate design requirements
- The PRA or alternative risk evaluations should be consistent with the design and assumptions
Changes to Address Public Comments (4/7)
- One comment requested clarification that supporting requirements may not be applicable or may not be reviewed
- For consistency with the existing discussion on page 5 of the ISG, staff reiterated on page 8 that the staff review should consider that all supporting requirements endorsed in industry standards may not be applicable at the CP stage
Changes to Address Public Comments (5/7)
- One comment requested references for alternative risk evaluations
- Staff is not endorsing particular alternative risk evaluation methods in this guidance document
- If the method can be justified to be applicable for its use, the staff will review the description provided in the CPA as described in this ISG
Changes to Address Public Comments (6/7)
- One comment requested a change to a statement included in the ISG on passive safety system reliability
- This statement is consistent with SRP Section 19.0
- This statement tells staff why this portion of the review may be important
- An applicant can justify on a case-by-case basis that this is not an important element for their design
Changes to Address Public Comments (7/7)
- One comment requested that the guidance clarify that some cases may result in the identification of no RTNSS non-safety-related SSCs
- The staff clarified in the ISG that RTNSS SSCs may not be identified for all designs following the RTNSS process
- The staff guidance includes reviewing the RTNSS process that determines that no RTNSS SSCs are identified
- The staff clarified that RTNSS SSCs may not be identified in the CPA depending on the use of the PRA and risk assessments and may be determined for the operating license application
Acronyms COL Combined operating license POS Plant operating state CP/CPA Construction permit/application PRA Probabilistic risk assessment DC Design certification PSAR Preliminary safety analysis report ISG Interim Staff Guidance RG Regulatory Guide LMP Licensing Modernization Project RTNSS Regulatory Treatment of Non-Safey Systems LPSD Low power and shutdown SRM Staff Requirements Memorandum LWR Light-water reactor SRP Standard Review Plan OL Operating license SSCs Structures, systems, and components
©2025 Nuclear Energy Institute l 1 May 21, 2025 ACRS - CP PRA Content
©2025 Nuclear Energy Institute 2 February 2025 NEI Comments By Federal Register (FR) notice (90 FR 4806) dated January 16, 2025, the Nuclear Regulatory Commission (NRC) requested comments on draft Interim Staff Guidance (ISG) document, Content of Risk Assessment and Severe Accident Information in Light-Water Power Reactor Construction Permit Applications.
NEI Provided Comment on February 18, 2025 7 of 9 comment were accepted or partially accepted in updated ISG provided for this meeting NEI is focused on consistency in the level of detail required for CP PRA information and specifically RG 1.253, which includes an Appendix A on CP PRA Guidance for non-LWRs.
NEI also sought consistency with the Part 53 Rulemaking which intends to be Technology-Inclusive as well as the ADVANCE Act
©2025 Nuclear Energy Institute 3 RG 1.253 Consistency
- A.3.2 the CP applicant should:
- 1. Identify all radiological sources, hazards, and POSs by performing a comprehensive and systematic search.
- 2. Disposition the search results by a combination of PRA logic modeling, acceptable screening methods, risk-informed supplemental evaluations, and crediting design-basis hazard levels (DBHLs).
- A.3.3 Regarding PRA acceptability, the minimum scope of the CP PRA logic model should include the internal events hazard group for the reactor in the at-power POS.
- A.3.7 The CP applicant may disposition certain hazards by crediting DBHLs in lieu of explicitly modeling these hazards in the PRA or accounting for them through a risk-informed supplementary evaluation.
©2025 Nuclear Energy Institute 4 RG 1.253 Consistency
- A.3.6 Regarding PRA acceptability, risk-informed supplemental evaluations may be used to disposition certain radiological sources, hazards, or POSs. NUREG-1855, Revision 1, Guidance on the Treatment of Uncertainties Associated with PRAs in Risk-Informed Decisionmaking (Ref. A-19), provides a generally acceptable approach for developing risk-informed supplemental evaluations. Section 1.3 of NUREG-1855 notes that the process described in NUREG-1855 is applicable to non-LWRs and reactors in the design stage; however, the screening criteria and the specific sources of uncertainty may not be applicable. Consequently, non-LWR CP applicants who use the guidance in NUREG-1855 to develop risk-informed supplemental evaluations should (1) describe and justify the use of reactor technology-specific screening criteria, and (2) explain how specific sources of uncertainty were identified and addressed.
©2025 Nuclear Energy Institute 5 SRM-SECY-23-0021 Consistency SRM-SECY-23-0021 - Proposed Rule: Risk-Informed, Technology-Inclusive Regulatory Framework for Advanced Reactors (bold is emphasis added by NEI)
- Screening tools and bounding or simplified methods may be used for any mode or hazard, provided that the applicant provides an acceptable technical basis. As with all risk-informed methodologies, treatment of uncertainties should be addressed.
- The staff should not apply consensus probabilistic risk assessment (PRA) standards as a strict checklist of requirements for Part 53 PRA acceptability determinations. Rather, the staff should allow PRA acceptability determinations for Part 53 applications to be appropriately flexible, considering how PRA insights are relied upon to support the licensing application, together with factors such as safety margin, simplicity of design, and treatment of uncertainties.
The staff should revise the proposed rule or preamble, as appropriate, to convey this point and also seek specific comment in the Federal Register Notice (FRN) for the Part 53 proposed rule on PRA acceptability for Part 53 applications in order to develop guidance.
©2025 Nuclear Energy Institute 6 Part 53 Consistency Part 53 - Proposed Rule: Risk-Informed, Technology-Inclusive Regulatory Framework for Advanced Reactors
- These requirements [53.415 and 53.510] would support either traditional deterministic approaches for determining and protecting against external hazards or probabilistic approaches that are being developed for seismic and some other external hazards.
- The analyses required for this demonstration would be described in proposed § 53.450(e),
which would require that those events be identified and assessed using a PRA methodology in combination with other generally accepted approaches for systematically evaluating engineered systems Existing processes for defining the scope and capability of a PRA supporting an application offer flexibility in determining the degree to which the PRA needs to be developed and may be informed by other factors such as design complexity and the needed degree of realism and level of detail, consistent with the use of the PRA and substance of the application. Such processes are currently available for appropriately defining the scope of the PRA and determining applicability of supporting requirements in consensus PRA standards needed to satisfy the proposed regulatory requirements for the specific uses of analyses under § 53.450(b).
©2025 Nuclear Energy Institute 7 ADVANCE Act Consistency Section 208 - Regulatory Requirements for Micro-reactors The Commission shalldevelop risk-informed and performance-based strategies and guidance to license and regulate micro-reactorsincluding strategies and guidance for(E) risk analysis methods, including alternatives to probabilistic risk assessments;
©2025 Nuclear Energy Institute 8 NEI Comment Summary
- Comments 1 & 2 -Clarification on ISG Scope was addressed
- Comment 4 - Changes to risk assessment was not addressed. NEI comment still stands, given hazards PRAs may be undeveloped, relative risk insights may be masked by modelling limitations and provide limited value.
- Comment 5 - Hazard risk evaluation requirements. This is inconsistent with RG 1.253, SRM-SECY-23-0021 and Part 53. LWRs should not be held to a higher standard than non-LWRs
- Comment 7 - Supporting Requirements was addressed
- Comment 9 - Consistency with RG 1.253 was partially addressed, see comment 5. Guidance in this ISG should be clear that traditional hazard design is sufficient for a CPA consistent with RG 1.253, SRM-SECY-23-0021 and Part 53.
©2025 Nuclear Energy Institute 9 NEI Comment Summary Outstanding Issues
- Consistent with RG 1.253, CP applicant may disposition certain hazards by crediting DBHLs in lieu of explicitly modeling these hazards in the PRA or accounting for them through a risk-informed supplementary evaluation. The ISG for hazard supplemental evaluations goes well beyond the requirements on RG 1.253. No risk-informed supplemental evaluation should be required for a CPA if traditional Hazard Design is applied.
- Low Power and Shutdown risk evaluation guidance and the discussion of POS remains too stringent for a construction permit PRA.
- POS should not have to facilitate realistic estimation of CDF and LRF if lower modes can conservatively be shown to not be risk-significant.
- Qualitative arguments for why lower modes should be bounded by full power operation should be sufficient for a CP. Anything else is not consistent with the SRP which requires certain LPSD events to be addressed deterministically.
©2025 Nuclear Energy Institute 10 Proposed Resolution Amend the ISG in a way that aligns with RG 1.253, Part 53 and the ADVANCE Act. For hazards and lower modes of operation, three options should be acceptable for a CP PRA.
- 1) PRA
- 2) Risk-Informed Supplemental Evaluation following guidance in ISG
- 3) Traditional Analysis credited as a supplemental evaluation: Hazard Analysis following RG 1.59, RG 1.76, etc. Lower Modes assessed in accordance with SRP Chapter 15
©2023 Nuclear Energy Institute 11 ACRS - Advisory Committee on Reactor Safeguards CP - Construction Permit CPA - Construction Permit Application DBHL - Design Basis Hazard Level FR - Federal Register ISG - Interim Staff Guidance LBE - Licensing Basis Event LWR - Light-Water Reactor NEI - Nuclear Energy Institute Non-LWR - Non-Light-Water Reactor NRC - Nuclear Regulatory Commission POS - Plant Operating State PRA - Probabilistic Risk Assessment SE - Supplemental Evaluation SRM - Staff Requirements Memorandum TICAP - Technology Inclusive Content of Application TI-RIPB - Technology Inclusive Risk-Informed Performance-Based Acronym List
Meeting Title May 21, 2025 Open Session Interim Staff Guidance:
Content of Risk Assessment and Severe Accident Information in Construction Permit Applications Attendees Michael Snodderly ACRS DFO David Petti ACRS Jennifer Lindeman Court Reporter Christopher Brown ACRS Scott Palmtag ACRS Shandeth Walton ACRS Vicki Bier ACRS Dennis Bley ACRS Steven Alferink NRR Craig Harrington ACRS India Banks NRR Matthew Hiser NRR Vesna Dimitrijevic ACRS Sandra Walker ACRS Stacey Rosenberg NRR Alissa Neuhausen NRR Sunwoo Park NRR Yan Gao X-energy Jim Schneider Jon Facemire NEI Jeffery Wood RES Walt Kirchner ACRS Ellery Coffman NRR Robert Roche-Rivera NRR Shilp Vasavada NRR Mihaela Biro NRR Marissa Bailey ACRS Doug Bowman Jason A. Christensen INL Mark Shaver NuScale Matt Sunseri ACRS Charles Moulton NRR David McClain NRR Keith Tetter NRR Anders Gilbertson NRR Sari Alkhatib X-energy Tracy Radel NRR Victoria Huckabay NRR Candace de Messieres NRR Todd Hilsmeier NRR Annie Kammerer ACRS Hanh Phan NRR