ML23264A865
| ML23264A865 | |
| Person / Time | |
|---|---|
| Issue date: | 09/07/2023 |
| From: | Advisory Committee on Reactor Safeguards |
| To: | |
| References | |
| NRC-2526 | |
| Download: ML23264A865 (1) | |
Text
Official Transcript of Proceedings NUCLEAR REGULATORY COMMISSION
Title:
Advisory Committee on Reactor Safeguards Docket Number: (n/a)
Location: teleconference Date: Thursday, September 7, 2023 Work Order No.: NRC-2526 Pages 1-196 NEAL R. GROSS AND CO., INC.
Court Reporters and Transcribers 1716 14th Street, N.W.
Washington, D.C. 20009 (202) 234-4433
1 1
2 3
4 DISCLAIMER 5
6 7 UNITED STATES NUCLEAR REGULATORY COMMISSIONS 8 ADVISORY COMMITTEE ON REACTOR SAFEGUARDS 9
10 11 The contents of this transcript of the 12 proceeding of the United States Nuclear Regulatory 13 Commission Advisory Committee on Reactor Safeguards, 14 as reported herein, is a record of the discussions 15 recorded at the meeting.
16 17 This transcript has not been reviewed, 18 corrected, and edited, and it may contain 19 inaccuracies.
20 21 22 23 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 UNITED STATES OF AMERICA 2 NUCLEAR REGULATORY COMMISSION 3 + + + + +
4 708TH MEETING 5 ADVISORY COMMITTEE ON REACTOR SAFEGUARDS 6 (ACRS) 7 + + + + +
8 THURSDAY 9 SEPTEMBER 7, 2023 10 + + + + +
11 The Advisory Committee met via 12 teleconference at 8:30 a.m., Joy L. Rempe, Chairman, 13 presiding.
14 15 COMMITTEE MEMBERS:
16 JOY L. REMPE, Chairman 17 WALTER L. KIRCHNER, Vice Chairman 18 DAVID A. PETTI, Member-at-Large 19 RONALD G. BALLINGER, Member 20 VICKI M. BIER, Member 21 CHARLES H. BROWN, JR., Member 22 VESNA B. DIMITRIJEVIC, Member 23 GREGORY H. HALNON, Member 24 JOSE A. MARCH-LEUBA, Member 25 ROBERT MARTIN, Member 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 1 THOMAS ROBERTS, Member 2 MATTHEW W. SUNSERI, Member 3
4 5 ACRS CONSULTANTS:
6 DENNIS BLEY 7 STEPHEN SCHULTZ 8
9 DESIGNATED FEDERAL OFFICIAL:
10 LARRY BURKHART 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
3 1 C-O-N-T-E-N-T-S 2 Welcome and Opening Remarks . . . . . . . . . . . 4 3 NRC Reviews of Volcanic Hazards Assessments for New 4 Reactor Licensing . . . . . . . . . . . . . . . . 5 5 Branch Technical Position (BTP) 7-19, "Guidance for 6 Evaluation of Defense in Depth and Diversity to 7 Address Common-cause Failure Due to Latent Design 8 Effects in Digital Safety Systems"/Preparation of 9 Reports . . . . . . . . . . . . . . . . . . . . 134 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 1 P-R-O-C-E-E-D-I-N-G-S 2 8:30 a.m.
3 CHAIRMAN REMPE: Good morning. The 4 meeting will now come to order. This is the second 5 day of the 708th meeting of the Advisory Committee on 6 Reactor Safeguards.
7 I'm Joy Rempe, Chairman of the ACRS.
8 Other members in attendance are Ron Ballinger, Vicki 9 Bier, Charles Brown, Vesna Dimitrijevic, Greg Halnon, 10 Walter Kirchner, Jose March-Leuba, Robert Martin, Dave 11 Petti, Thomas Roberts, and Matthew Sunseri. I note we 12 do have a quorum.
13 Similar to yesterday the Committee is 14 meeting in person and virtually. The communications 15 channel has been opened to allow members of the public 16 to monitor the Committee discussion.
17 Mr. Larry Burkhart is the designated 18 federal official for today's meeting.
19 During today's meeting the Committee will 20 consider the following topics: NRC Reviews of Volcanic 21 Hazards Assessments for New Reactor Licensing and 22 Branch Technical Position BTP 7-19, Guidance for 23 Evaluation of Defense-in-Depth and Diversity to 24 Address Common-Cause Failure due to Latent Design 25 Effects and Digital Safety Systems.
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5 1 Portions of the sessions for today's 2 topics may be closed as stated in the agenda. A 3 transcript of the open portions of the meeting is 4 being kept and it is requested that speakers identify 5 themselves and speak with sufficient clarity and 6 volume so they can be readily heard. Additionally, 7 participants should mute themselves when not speaking.
8 So at this time I'd like to ask other 9 members if they have any opening remarks.
10 (No audible response.)
11 CHAIRMAN REMPE: Not seeing any hands up 12 on the internet or in the room, I will then move 13 forward. And I'd like to ask Walter Kirchner to lead 14 us in today's first topic.
15 Walt?
16 MEMBER KIRCHNER: Thank you, Madam 17 Chairman.
18 So this morning we are going to have an 19 informational briefing on volcanic hazards assessments 20 for new reactor licensing. And just by way of 21 background; and I'll keep my opening comments short, 22 we had a previous presentation on the Reg Guide for 23 volcanic hazards assessment; that's 4.26, and wrote a 24 letter on the topic in April of 2021. Our conclusions 25 in brief were that this was reasonable guidance that 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 1 the Reg Guides should be exercised through trial 2 applications. And there were some interesting 3 research topics there on the impact of the volcanic 4 hazards on SSCs to look at, in particular ash falls, 5 which we'll hear more about this morning.
6 There was a Rev 1 version issued to take 7 care of some of the administrative matters in August 8 of 2023. And as it turns out the trial applications 9 are upon us. We have -- or more directly the NRC has 10 a white paper from the clean carbon-free power plant 11 proposal for the Idaho site, as well as a TR from 12 TerraPower for the Natrium site in Wyoming. So the 13 trial applications are upon us and -- and as the 14 staff.
15 With that I'm going to turn to Eric Benner 16 for opening comments from the NRC staff and then we 17 will subsequently hear from Jenise Thompson who will 18 take us through her presentation on the topic.
19 Eric?
20 MR. BENNER: Thank you, Chair Rempe, 21 Member Kirchner, and all members.
22 I do note that I will be the SES -- NRR 23 SES representative for both of these topics today, 24 which might strike you as kind of unusual, but the 25 external hazards function is in my division and I call 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 1 it the cool part of my division's work.
2 So I am as enthused probably as you are to 3 hear this topic today. As Member Kirchner said, we 4 did the Reg Guide and presented it before you.
5 Today's presentation will build on that presentation 6 as the ongoing activities and as mentioned Jenise 7 Thompson, our expert in this area, will be leading the 8 presentation.
9 She'll be discussing the ongoing 10 activities, but will not be diving too deep into the 11 site-specific details of the reviews because they're 12 on their own track. So we certainly will have ongoing 13 -- I expect we'll have ongoing discussion with the 14 Committee on these issues moving forward. So with 15 that I will just turn it over to Jenise.
16 MS. THOMPSON: Thank you, Eric.
17 I'm sure everyone can see the slides. I 18 can see them up.
19 Thank you, Barb, for presenting the slides 20 for us today.
21 I wanted to start with a little bit of 22 geo-trivia suggested by my deputy division director 23 who I believe is a Jimmy Buffett fan. And the song 24 Volcano was written and recorded in a studio near the 25 Soufriere Hills volcano in Montserrat, but the volcano 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 1 did not actually erupt on Jimmy Buffett. It did not 2 erupt until 16 years after that album was issued. And 3 the song Volcano is to my knowledge the only popular 4 song that mentions both volcanos and Three Mile 5 Island. So there's a nuclear and volcano connection 6 to that. And I know Jimmy Buffett's been in the news 7 lately. So I'll start with that small anecdote of 8 geo-trivia to get us going.
9 Barb, the slides have disappeared. I'm 10 not sure why that is.
11 But while we're waiting for those to come 12 back, again my name is Jenise Thompson. I'm a 13 geologist in the External Hazards Branch. I was the 14 technical lead on Reg Guide 4.26, which as many of you 15 members may recall, was a cross-agency team to develop 16 that Reg Guide. We also had some --
17 MS. HAYES: (Audio interference) to get 18 these slides back up.
19 MS. THOMPSON: Thanks, Barb.
20 And today I'll go into detail, kind of a 21 where we started and where we're going, so what we 22 have accomplished thus far and what we're going to go 23 into the future.
24 I see we already have a hand up, so I'll 25 pause and take that question.
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9 1 CHAIRMAN REMPE: Dennis, I believe your 2 hand is up. If you had a question?
3 DR. BLEY: It is. I had a little trouble 4 getting my mic turned back on.
5 Jenise, back a couple years ago when you 6 presented this we sent a letter, and Walt talked about 7 that one, and in that letter the staff agreed with 8 essentially all of our three major points and talked 9 a bit about the issue of effects on SSCs of volcanic 10 hazards and especially the issue of volcanic dust and 11 its small size and how it can cause problems.
12 You said the staff was aware of a research 13 project at the AEA. You were following that. I 14 notice there's no mention of any new information in 15 this Reg Guide. If you're planning to talk about that 16 at some point, that would be great. If you weren't, 17 I'd like to hear a little more about why we're not 18 seeing anything yet.
19 MS. THOMPSON: Yes, so I can address that.
20 Barb, we're seeing your Teams chat right 21 now.
22 But I'll address the comment first before 23 getting back to the presentation.
24 We did go looking for some information on 25 the effects of volcanic ash on nuclear SSCs. I know 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 1 that the Committee pointed us to some research on the 2 effects of sandstorms and sand particles on a facility 3 in UAE. We did not pursue that further at this time 4 because the difference in -- basically the difference 5 between a sand hazard versus a volcanic hazard, the 6 material property differences that would be 7 considered.
8 And also because looking ahead to the 9 potential evaluation of the effect of whatever the 10 screened in volcanic hazard may be for a selected 11 site, the effect on SSCs is going to be very 12 technology-specific and technology-dependent. So we 13 didn't feel that we had enough information on the 14 potentially affected SSCs, the magnitude of the hazard 15 to pursue that line of inquiry at this time.
16 It is something that we're mindful of 17 going forward, looking into how we're preparing for 18 these reviews and what additional capabilities for 19 staff expertise will be needed in the assessment of 20 the effect of volcanic hazards on nuclear structure 21 systems or components, but again we're taking more of 22 a site-specific focus because it's a very broad scope 23 of potentially impacted SSCs. If we were to look at 24 every design that is potentially a future applicant 25 that may need to consider volcanic hazards.
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11 1 So that's something that we're still 2 mindful of looking ahead to, but we don't feel that we 3 have the full scope of information to make an informed 4 research project of it right now.
5 DR. BLEY: Okay. Thank you. We look 6 forward to hearing more in the future in this area.
7 We also pointed out that the Guide 8 suggested that there was sufficient guidance on 9 addressing the issue of volcanic hazards on equipment 10 in an ANS document and in NEI 18-04. I see that the 11 call out to NEI 18-04 has disappeared, but we pointed 12 out back to the staff that those documents only warn 13 analysts to consider the kind of problems that are 14 there, but don't really give them any guidance on how 15 to deal with it. I guess we'll see something in the 16 two applications that Walt pointed out earlier, so we 17 look forward to that.
18 And I had just a quick question in that 19 area, because I don't think you'll be talking about 20 those in any length. In one of those papers they make 21 strong use of a paper on the Volcanic Explosivity 22 Index, which I don't think you talk about much, 23 especially a paper by Newhall and Self in '82, which 24 came a couple years after Mount St. Helens and seems 25 to have taken account of that.
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12 1 Is that going to be an important document 2 for you and are you likely to pull it into the 3 guidance?
4 MS. THOMPSON: You're asking specifically 5 about the Newhall paper?
6 DR. BLEY: I am.
7 MS. THOMPSON: So at this time we don't 8 have plans to include that in the -- in a future 9 revision to Reg Guide 4.26. And whether it becomes an 10 important factor in these future reviews for the 11 volcanic hazards assessments that are submitted in 12 support of these license application reviews is going 13 to be very dependent on the information that the 14 applicants are providing and the resources and 15 research papers that they're relying on to build the 16 safety case for the adequacy of the volcanic hazards 17 assessment that they have performed and whether or not 18 those research papers would be included. I could only 19 speculate.
20 DR. BLEY: Okay. Well, thank you. And 21 I'll listen to what you have to say now. I think I'm 22 still at the point of seeing this as a good general 23 overview of how you approach the issue, but pretty 24 light on exactly how you deal with it and what's the 25 approved approach if you rely upon this Reg Guide.
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13 1 But we'll look forward to your talk. Go ahead.
2 MS. THOMPSON: Yes, and you're keying off 3 of something that is correct. This is really intended 4 to be a more general overview of where we're at, what 5 we've completed thus far, what we're currently doing 6 and what we're expecting to do in the near term with 7 respect to volcanic hazards for these future license 8 reviews and -- or application reviews. So I purposely 9 did not go into detail because again we don't have 10 docketed information for one of the sites.
11 We have a topical report that is still 12 under active review, so we don't have the staff's 13 final conclusions to share at this point. So I'm 14 really talking at a higher level of how we're 15 anticipating Reg Guide 4.26 as being implemented based 16 on our previous interactions and some of our pre-17 application engagement with some of these applicants 18 in the last couple of years and what we're doing as a 19 staff to prepare -- to provide the best review we can 20 for those volcanic hazards assessments.
21 So I'll get into the presentation now 22 unless there are some additional questions. This is 23 meant to be kind of an overview slide of some of the 24 topics that I'll be touching on in today's 25 presentation including the issuance of Reg Guide 4.26.
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14 1 We've also been involved in the review of 2 the Carbon Free Power Project, or CFPP, volcanic 3 hazards white paper, which was outlining the planned 4 approach that CFPP is taking in the performance of 5 their volcanic hazards assessment. So we didn't get 6 into technical discussions of what are the specific 7 hazards and sources of volcanic hazards that are being 8 considered for that particular application. So I want 9 to make sure that that's clear as well.
10 So that review was completed by the staff, and 11 I'll get into that a couple more slides.
12 We've also been observers to a Department 13 of Energy project at the Idaho National Laboratory.
14 They are undertaking a Level 3 SSHAC to consider 15 volcanic hazards at the entire INL location, and the 16 NRC staff has been observers to that ongoing activity.
17 And we've also in the course of supporting pre-18 application engagement with the Carbon Free Power 19 Project and as observers to the INL SSHAC been out to 20 the Eastern Snake River Plain in Idaho to visit and 21 see some of these volcanic features directly in the 22 field as part of these activities.
23 And then looking ahead to some of our 24 ongoing and upcoming activities, we do have the 25 TerraPower Volcanic Hazards Topical Report review 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
15 1 which is ongoing. So again we won't be going into 2 detail of that specific application or that topical 3 report right now, but we will I suspect be back before 4 you before too long to discuss what the staff's 5 conclusions were with respect to that topical report.
6 And all of this is building up to the staff supporting 7 the licensing reviews for the CFPP and TerraPower 8 applications which we're expecting in the not-too-9 distant future.
10 So we'll go to the third slide, please, 11 Barb.
12 And we'll start with the regulatory 13 requirements. For many of you this is going to be a 14 rehashing of the intro to Reg Guide 4.26, but I did 15 kind of want to give an overview because I know that 16 there may be some new people at the table on the 17 Committee or some members of the public who were not 18 involved or participants or attending the previous 19 briefings on Reg Guide 2.46.
20 So the regulatory requirements are listed 21 here, specifically 10 CFR Part 50, Appendix A, 52.17 22 for early site permits, and 52.79 for combined 23 licenses. And the only specific mention of volcanic 24 activity in the applicable regulations is in Reactor 25 Site Criteria 102.3 where volcanic hazards or volcanic 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 1 activity should be considered as one of the geologic 2 or seismic factors that may impact the design and 3 operation of these nuclear power facilities.
4 We'll go onto the next slide, please, and 5 talk about Reg Guide 4.26. That was a great summary 6 of the activities related to 4.26. This is outlining 7 a method to assess volcanic hazards for new nuclear 8 power reactor sites. You recall I was up before the 9 Committee twice before in February of 2020 and in 10 April of 2021. I promise -- there shouldn't be a ton 11 of overlap between those presentations and this one, 12 but it may be useful to go back and look at some of 13 those slides if there are some additional questions 14 that I don't cover.
15 Rev 0 was issued in June of 2021. You can 16 pull it up at the ML here. As they mentioned just 17 last month we processed Revision 1 as an 18 administrative change. Something I want to emphasize 19 about that administrative change is we earlier this 20 year became aware of two paragraphs and two bullet 21 points that were inadvertently deleted during the 22 final document processing of Reg Guide 4.26 in its Rev 23 0 form.
24 So the version that was shared and 25 distributed for public comment in the summer of 2020 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 1 and the version that was shared to this Committee in 2 April of 2021 had those two paragraphs and two bullet 3 points. So the only changes from Rev 0 to Rev 1 are 4 the restoration of the text that should have been 5 included initially in that Rev 0 but was omitted. So 6 that's the key difference there. There have been no 7 other substantive changes to the guide in that Rev 1.
8 And then finally I'll walk through in the 9 next couple of slides the flow chart we provide in Reg 10 Guide 4.26, which if you recall it has options for an 11 applicant. So an applicant may choose to perform a 12 more detailed assessment of the specific volcanic 13 hazard or they can do what we call the engineering 14 analysis option which allows them to perform basically 15 a screening to determine a maximum magnitude hazard 16 and then move forward in the process to consider the 17 effect of that maximum magnitude hazard on the 18 structure, systems, and components for their selected 19 design.
20 So we'll go to the next slide, please, and 21 we'll walk first through the hazard analysis. And 22 I'll do this much more briefly than in previous 23 presentations, but something to keep in mind is we 24 built in a lot of flexibility to this volcanic hazards 25 analysis approach. And that's intended to give the 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
18 1 applicants the ability to leverage these off-ramps so 2 that it's not intended to be a start-to-finish, you 3 must do all of these steps to have an adequate 4 volcanic hazards assessment. You can use the 5 information that you have. You can use the hazard 6 information, the engineering information, risk 7 information and leverage those off-ramps once you've 8 reached an acceptable conclusion or an acceptable 9 result.
10 So it starts at step 1, which is 11 leveraging the geologic history and geological site 12 characterization information. This is information 13 that's going to be required in the application anyway, 14 so looking whether there are quaternary volcanos in 15 the site region or quaternary volcanic deposits in the 16 site vicinity, the quaternary period being the most 17 recent roughly 2.6 million years of earth history and 18 the site region being a 200-mile radius or 320-19 kilometer radius from the site and the site vicinity 20 being that 25-mile or 40-mile radius.
21 And if either of those questions are 22 answered in the affirmative, then an applicant would 23 proceed into the next step of the volcanic hazards 24 assessments. So this information should be readily 25 available to most application -- or most applicants as 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 1 part of their application development for these 2 permits and licenses that they'd be applying for.
3 Another important component here which 4 isn't reflected in the flow chart but is reflected in 5 the text of Reg Guide 4.26 is the development of the 6 tectonomagmatic model. And I know we went into a 7 little bit more detail of that in the April 2021 8 presentation. And that is just a consideration of 9 what are the driving forces for volcanism in the 10 region of interest or for this time period of 11 interest.
12 It's not a numerical model. It's really 13 a conceptual model looking at the processes driving 14 volcanism to understand what they are, what's 15 controlling volcanism in that area, to look at what's 16 the potential for a future event in that site that 17 would be consistent with the current conditions of 18 that volcanic system. Because volcanic systems are 19 dynamic. We're not going to see static systems for 20 some of these locations and recognizing that not all 21 volcanos may result in being a potentially -- a 22 potential source of hazards given the current 23 environment in which their system is existing. So 24 allowing for that flexibility of using that geologic 25 information to inform that decision as well becomes an 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 1 important factor in the early steps of this hazard 2 analysis or volcanic hazards assessment process in Reg 3 Guide 4.26.
4 But we're going to assume that they're 5 moving forward, that an applicant would move into 6 screening volcanic hazards. And again you can see 7 this is where another off-ramp exists where if those 8 hazards can reasonably be screened out for whatever 9 information is available then that would end the 10 assessment. If not, they would move into developing 11 initial insights. And if those risk insights are 12 considered acceptable, then that would also allow an 13 applicant to end the assessment.
14 We're going to skip ahead from the 15 engineering analysis option and assume that an 16 applicant would move forward into step 4. And this is 17 where they would evaluate the eruption potential 18 and/or hazard potential. You'll note that in Reg 19 Guide 4.26 the NRC does not endorse the use of one 20 particular model or code to consider those -- or to 21 evaluate those eruption potentials or hazard 22 potentials. I feel like I'm going to -- you may think 23 I'm a broken record by the end of the presentation 24 today, but that's going to be a site-specific decision 25 and an applicant decision to be made.
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21 1 We've also in Reg Guide 4.26, particularly 2 in the explanation of step 4 -- this is where those 3 two paragraphs and two bullet points were 4 inadvertently omitted. And those are two important 5 paragraphs and some important bullet points that 6 provide guidance to an applicant on what the 7 appropriate level of model support would be. So 8 providing the justification for why the selected 9 numerical model is appropriate for the source volcano 10 and the potential hazards that are being considered 11 for that source volcano and giving the applicant the 12 flexibility to choose the method that they believe is 13 best applicable to their site-specific circumstances 14 and their selected design.
15 And then once that is completed an 16 applicant would move into step 5 and looking at 17 developing some risk insights, which if acceptable 18 would end the assessment. And I know there was a 19 comment earlier about NEI 18-04. And I can confirm 20 that in the development of risk insights here in step 21 5 Reg Guide 4.26 does address the use of NEI 18-04, 22 referring back to Reg Guide 1.233 which endorses that 23 NEI document. So if there were some additional 24 questions on that, I would point to that section and 25 also back to Reg Guide 1.23.
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22 1 But also note that when talking about 2 risk-insights and PRA information, particularly 3 looking at uncertainties in volcanic hazards and 4 volcanic systems, we're talking about uncertainties 5 that can be on the order of several orders of 6 magnitude. So here in the risk-insights consideration 7 it may need to include non-PRA information for that 8 particular hazard assessment.
9 And if an applicant is still within the 10 process they would proceed to steps 6 and 7, which are 11 also some of the key steps in the engineering and 12 analysis option. So we'll go to the next slide.
13 And the next slide is -- the red boxes are 14 showing what the engineering analysis option would 15 look like. And the focus here on this engineering 16 analysis is to determine a maximum magnitude hazard 17 for those volcanic hazards that have screened in step 18 2 and then use that maximum magnitude hazard to 19 evaluate the SSC performance and potentially 20 evaluating mitigating actions.
21 And the iteration between step 6 and step 22 7 as shown by the double-pointed arrow here is to 23 allow an applicant to implement mitigating actions if 24 needed to augment or ensure the continued performance 25 of that SSC under the maximum magnitude volcanic 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 1 hazard that needs to be considered based on that 2 initial screening up in step 2, so allowing for that 3 iteration so that if the SSC performance under the 4 maximum magnitude hazard is not acceptable without 5 some kind of augmented action or implemented action to 6 support that SSC through the volcanic hazard event at 7 the site to allow for that in the process.
8 And also as we're looking ahead this is 9 where -- as we plan for these future licensing reviews 10 of volcanic hazards assessments this is where our tie-11 in with the nuclear engineers and systems engineers 12 would be potentially very important in providing that 13 maximum magnitude hazard for those engineers to then 14 assess the performance of the SSC and then working 15 together to determine are those mitigating actions 16 reasonable to be implemented in the amount of time you 17 have between the notification of the impending event 18 and the arrival of the hazard at the site and if those 19 mitigating actions are going to improve the SSC 20 performance to a level that would be considered 21 acceptable?
22 So that is essentially Reg Guide 4.26 in 23 a nutshell. We'll go onto the next slide and just 24 talk about some of the key inputs --
25 MEMBER KIRCHNER: Jenise?
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24 1 MS. THOMPSON: Yes?
2 MEMBER KIRCHNER: This is Walt Kirchner 3 just briefly on that last slide. Just an observation 4 that depending on the analysis of the vulnerability to 5 volcanic events an option is changing the site or 6 relocating to a higher elevation. I think we'll see 7 that for the two applications that are coming your 8 way.
9 MS. THOMPSON: So --
10 MEMBER KIRCHNER: (Audio interference) and 11 actually choosing a site at a higher elevation to 12 avoid lava flows or debris flows or flooding, et 13 cetera, et cetera. So it's more of a macro iteration 14 rather than an SSC by SSC consideration.
15 MS. THOMPSON: So it could be a macro 16 iteration. I think in general the approach we've 17 taken in 4.26 is with the hope that an applicant would 18 not get down into step 6 or step 7 and then realize 19 that they would need to consider a different location 20 for their site. And maybe some of that information 21 looking at local topography and where past hazards 22 have been mapped or observed in the site area or site 23 vicinity -- that may be something for an applicant to 24 consider earlier in the process closer to step 1 when 25 looking at initial siting determinations.
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25 1 But if it comes down to it and step 7 -- 6 and 2 7 can't iterate an acceptable performance of the SSCs, 3 then a change in site may be necessary.
4 Were there any other questions before I 5 move onto the next slide?
6 (No audible response.)
7 MS. THOMPSON: All right. So we'll go 8 onto slide 7. So as we take this approach to 9 reviewing volcanic hazards assessments it's a 10 multifaceted approach. We're gathering -- we expect 11 that the applicants will be gathering a fair amount of 12 information. This is what we'll be looking at as part 13 of our review. Again not just the geologic history or 14 the site characterization information, but how all of 15 that information is informing the tectonomagmatic 16 model for an applicant to determine which sources of 17 volcanic hazards, if any, would need to be considered 18 because they are considered consistent with the 19 tectonomagmatic model for their selected site 20 location.
21 We're also looking at numerical modeling.
22 We know that in step 4 -- that's generally where we 23 talked about it in Reg Guide 4.26, but we also know 24 that some applicants are choosing to use numerical 25 modeling to inform their screening decisions earlier 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
26 1 in the process, which is a completely acceptable use 2 of numerical modeling in this context. And we're also 3 looking internally at our own expertise so that we're 4 prepared to not just review those numerical models, 5 but have an understanding of their development so that 6 we can better review the justification for the 7 acceptability of that model for that selected site and 8 if necessary to perform any confirmatory calculations.
9 And this is where we're working as a wider 10 external hazards team because we do have -- some of 11 our meteorology team have been providing -- have been 12 doing numerical modeling in support of atmospheric 13 dispersion for many years. And so using some of that 14 expertise as we prepare to review tephra dispersion 15 modeling and also working with our seismology and 16 geophysics team in both NRR and the Office of Research 17 who have extensive modeling experience as it relates 18 to seismic hazards and seeing where we can learn from 19 and work with each other to have this capability in 20 house.
21 And then finally looking at are there any 22 other engineering considerations that need to be 23 brought to mind as we look at these volcanic hazards 24 assessments both from the effect on SSCs that are 25 going to be relied upon to operate at their intended 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
27 1 safety function during these events and also looking 2 at are there any structure or geotechnical engineering 3 considerations that we need to be mindful of looking 4 at the early construction process and foundation 5 interfaces looking at whether there needs to be any 6 concerns about fractured rock encountered in the sub-7 surface or vesicular rocks encountered. You can see 8 the photo here on the right is showing some pipe 9 vesicles in a volcanic rock in Eastern Idaho.
10 So what are some of those engineering 11 considerations? And these are conversations that we'd 12 be having as part of any license review with 13 counterparts, but looking at whether there are any 14 unique engineering considerations that we need to be 15 mindful of going forward with these volcanic hazards 16 assessments and associated license reviews.
17 So we'll go to the next slide, please. We 18 do have some completed and ongoing activities that 19 have already been mentioned briefly, and I'll talk to 20 them again on this slide here. The Carbon Free Power 21 Project white paper came in, as I mentioned before.
22 This was really focused on the planned approach that 23 they're taking to performing their volcanic hazards 24 assessment and asking for a determination of whether 25 that was considered acceptable and consistent with Reg 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 1 Guide 4.26.
2 Notably for the Carbon Free Power Project 3 they expanded the site vicinity from a 25-mile radius 4 to a 35-mile radius. And the justification they 5 provided for that is that allows them to include two 6 additional quaternary volcanic fields in the Eastern 7 Snake River Plain. And so that was one of the changes 8 that they have taken from Reg Guide 4.26.
9 This is also the applicant that is 10 planning to use numerical modeling to inform the 11 screening decision in step 2 and also to allow them to 12 better refine their maximum magnitude hazard for using 13 an engineering analysis option. So using that 14 numerical modeling that is described in step 4 of the 15 flow chart earlier in the process is something that we 16 determined as a staff was considered consistent with 17 Reg Guide 4.26. And if you're interested, you can 18 read the full staff assessment from last fall at the 19 ML listed here.
20 I also mentioned at the start that the 21 Idaho National Laboratory is undertaking a Level 3 22 SSHAC. That's the Senior Seismic Hazard Analysis 23 Committee process. This is a process that's endorsed 24 in Reg Guide 4.26 as one way to conduct an expert 25 elicitation in part of -- as a performance of the 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 1 volcanic hazards assessment. This is a process that 2 we've used extensively to assess seismic hazards in 3 the past at nuclear facilities. And the staff are 4 very familiar with this process considering it allows 5 an applicant to consider the center body and range of 6 technically defensible information.
7 So we've had an observing team in all 8 three of the workshops being conducted for this site-9 wide PVHA at the Idaho National Laboratory. We've 10 also were included in the field visit in which the 11 SSHAC participants were observing features in the 12 field that may play into the final report for this 13 particular project.
14 The final report has not yet been issued, 15 but we do expect that future applicants considering 16 sites at the Idaho National Laboratory may use that 17 report as the basis for their future volcanic hazards 18 assessment, which is why we've been following this 19 project relatively closely over the last few years, 20 because it would be an important input to those 21 potential future applicants.
22 DR. BLEY: Jenise?
23 MS. THOMPSON: I see another hand has gone 24 up, so I'll pause.
25 DR. BLEY: Yes, it's Dennis again. These 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 1 models -- I wonder if you can say anything about where 2 the staff stands and how they've review the -- I'll 3 call it the reliability of such models. It strikes me 4 -- as opposed to the atmospheric modeling where we get 5 lots of chances to look at -- to see how they perform 6 under various conditions. Here, unless we have a 7 really good record before a volcanic event, once it's 8 happened some of the evidence that you would use in 9 your model before that has been destroyed.
10 How do we have confidence in these models?
11 MS. THOMPSON: So I actually have a slide 12 later in the presentation that talks a little bit to 13 the numerical models that we know applicants are 14 using --
15 DR. BLEY: Okay. That's good.
16 MS. THOMPSON: -- but I will say that the 17 justification for the use of one model over another is 18 something that is a case that the applicant is going 19 to need to make, which is why we've provided that 20 explanation of adequate model support in Reg Guide 21 4.26. And like I said, we're doing some background 22 work right now to have a better understanding of the 23 use of these models in the past so that when we see 24 those models being used in a future application we're 25 not starting from zero. We've already built up some 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
31 1 internal knowledge and workability with those 2 particular models. But I do have a numerical modeling 3 slide later where I'll talk a little bit to it.
4 But in general the NRC -- there are many 5 different models that could be used and it wouldn't be 6 efficient for us to go through any kind of validation 7 or verification for every single model that is 8 available, which is why the burden for that and the 9 justification for that has fallen to the applicants 10 here to justify their use of a selected model.
11 DR. BLEY: Okay. I'll wait for that next 12 slide.
13 MS. THOMPSON: Okay. It's towards the end 14 of the presentation. It's not immediate, but we will 15 get there.
16 So I think I was on the last bullet here, 17 which is the TerraPower volcanic hazards assessment.
18 This is the topical report that was submitted earlier 19 this year. This is a report that is still under 20 active review. The staff are still working through 21 their review and documenting their findings, so I 22 won't go into detail on this, but this is on our 23 radar. It's an ongoing activity that we have a team 24 put together who are actively engaged in that review 25 at this time.
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32 1 We'll go onto our next slide, please.
2 DR. SCHULTZ: Excuse me, Jenise. This is 3 Steve Schultz. Jenise, on the previous slide --
4 MS. THOMPSON: Okay.
5 DR. SCHULTZ: -- you mentioned that the 6 Idaho National Laboratory is following the Senior 7 Seismic Hazard Analysis. And in your review of the 8 Carbon Free Power Project you note that that work is 9 not following the Senior Seismic Hazards Analysis 10 Committee work exactly, but you referred in the white 11 paper review that they're leveraging the concepts of 12 that work and they're focusing on -- as a result on 13 some of the issues associated with uncertainty.
14 Could you just expand on that statement?
15 It's only a brief statement in your review of the 16 white paper and I wanted to better understand why 17 they're not using more work that's ongoing at Idaho 18 National Laboratory and what it really means when you 19 say that they're leveraging that work.
20 MS. THOMPSON: So essentially it boils 21 down to schedule. So based on our interactions for 22 both the INL V-SSHAC and the Carbon Free Power Project 23 pre-op engagement the INL V-SSHAC is on a different 24 completion schedule than the Carbon Free Power 25 Project. So by the time the INL report is finalized 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
33 1 the CFPP project intends to be further along in their 2 application development process. But there is a fair 3 amount of overlap in supporting staff to both the INL 4 PVHA work and the people who are assisting the Carbon 5 Free Power Project in doing the volcanic hazards 6 assessment for that.
7 So that's essentially what I mean. It's 8 just a schedule difference, but there is a number of 9 overlap in technical experts that are involved in both 10 of those particular projects.
11 DR. SCHULTZ: What's the relative schedule 12 for those projects? When you say they don't quite 13 sync up, does that mean one is not going to be done 14 for three or four years and the other needs to be done 15 in one year, or what does that really mean? How long 16 or what's the time frame of these? Are we into 17 seismic hazard evaluation that goes on for decades?
18 MS. THOMPSON: We're not definitely in the 19 years standpoint, but I don't think the -- and I don't 20 own -- I'm not responsible for either of these two 21 projects, but I believe that --
22 DR. SCHULTZ: Sure.
23 MS. THOMPSON: -- the INL final report is 24 expected sometime towards the middle of next calendar 25 year. And I believe that CFPP was looking for an 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 1 earlier date than that to submit their application.
2 But I would also defer to Omid, the safety PM for CFPP 3 if he wanted to chime in with any other calendar 4 information, because that's I think the best I have at 5 this point.
6 MR. TABATABAI: Good morning. Yes --
7 MS. THOMPSON: But it's not years; it's 8 definitely months.
9 MR. TABATABAI: Yes, thank you, Jenise.
10 This is Omid Tabatabai. CFPP will submit 11 the application in January of 2024. So Jenise is 12 right.
13 DR. SCHULTZ: That helps. Thank you very 14 much.
15 MS. THOMPSON: Were there any other 16 questions on this slide?
17 (No audible response.)
18 MS. THOMPSON: Okay. So moving ahead, I'm 19 going to speak a little bit towards the prospective 20 site locations and some of the regional volcanic -- or 21 sources of volcanic hazards of interest in previous 22 briefings. So again, I'm not going to speak to 23 specific hazard levels or magnitudes of hazards or 24 probabilities today because that would be premature 25 since we don't have these application. They're under 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
35 1 review or the application -- the topical report that 2 we do have under review is still in the review 3 process.
4 But showing here the -- this is a map from 5 the Yellowstone Volcano Observatory at the U.S.
6 Geological Survey. It has the statutory role for 7 monitoring volcanic hazards in the United States and 8 issuing alerts if they determine that an event may be 9 forthcoming.
10 The orange line is just showing the 11 boundary for the Yellowstone Volcano Observatory, so 12 we don't really need to pay attention to that.
13 The two purple stars, the one in Central 14 Idaho or Eastern Idaho is the INL location and the one 15 is Southwestern Wyoming is the TerraPower site. These 16 are just rough estimates of the location.
17 And the green triangles are showing the 18 actively monitored volcanos under the observatory 19 system. So obviously Yellowstone in Northwestern 20 Wyoming is I know a source of interest from previous 21 briefings that we've given on volcanic hazards and 22 along the West Coast of the U.S. You can see a lot of 23 green triangles and those are the volcanos of the 24 Cascade Observatory. And then further into Northern 25 California the California Observatory.
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36 1 The white triangles are what are termed 2 unassigned sources, or volcanic features. So these 3 are sources that the USGS in looking at the current 4 state of the system; remember that tectonomagmatic 5 model, do not warrant as active monitoring as these 6 green triangles. I don't want to say that they're not 7 monitored because a lot of these areas still have 8 installed instrumentation that can inform smaller 9 scale monitoring, but they don't rise to the level of 10 the USGS feels that they need to take a more active 11 monitoring role for those particular sources.
12 And then in Eastern Idaho kind of this 13 oval shape in the center is representative of the 14 Eastern Snake River Plain, which is a quaternary 15 distributive volcanic field in which the INL location 16 is located. And you can see there's three unassigned 17 volcanic sources here. And I'll talk a little bit 18 about each of those in a subsequent slide looking at 19 the Eastern Snake River Plain, but I wanted to give 20 kind of a regional perspective of where these two 21 sites that we know that we need to be prepared to 22 review these volcanic hazards assessments are located 23 and what some of those volcanic sources of past 24 interest may have been.
25 So we'll go to the next slide and look 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 1 specifically at the Eastern Snake River Plain. And 2 this is from a paper from Gallant et al, from about 3 five years ago showing the age of the basalts on the 4 Eastern Snake River Plain. And I hope you can 5 visualize how this is truly a distributed volcanic 6 field. The youngest age of basalts are spread out 7 across a wide area within the Eastern Snake River 8 Plain. This isn't just a source of volcanic hazards 9 because it's going to be a pinpoint source one GPS 10 coordinate on the map. This is going to be a wider 11 scale potential source of hazards here.
12 You can see the -- kind of in the upper 13 right quadrant the outline of the INL property in that 14 thick black line and then these darker blue basalts 15 are the youngest of the basalts here. Just to the 16 east of the INL property is the Hell's Half Acre lava 17 field, which is just over 5,000 years old. I think 18 it's 5,200 plus or minus. The smaller flow in the 19 center, the only one -- the youngest flow that comes 20 onto the INL property proper is the Cerro Grande, 21 which is just under 11,000 years. The largest by area 22 just to the west of the INL is the Craters of the Moon 23 lava field, which is just over 2,000 years old. And 24 then to the south is the Wapi Field, which is also 25 about the same age as the Craters of the Moon.
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38 1 So looking at the approach that CFPP has 2 taken in their white paper that expanded their site 3 vicinity to include both the Hell's Half Acre source 4 and Craters of the Moon. And we expect that when 5 looking at the Eastern Snake River Plain -- I know we 6 talked about siting considerations and whether you 7 would need to move your site.
8 And then looking at the plain, it's --
9 there's a fair amount of topography that is sometimes 10 unexpected, so a lot of localized topographic highs 11 and lows and the effective topography in looking at 12 volcanic hazards. Particularly those from lava flows 13 is potentially going to be an important factor when 14 looking at hazards for the Eastern Snake River Plain 15 that may screen in for these sites. But again we'll 16 talk more in detail about what those specific hazards 17 would be, what the probabilities would be, and what 18 the potential hazard magnitudes would be once we have 19 that information submitted by an applicant. But I did 20 want to touch on the Eastern Snake River Plain because 21 I know we've had some questions from it in the past.
22 But before I go on are there any questions 23 for this slide?
24 (No audible response.)
25 MS. THOMPSON: Okay. Then we'll go on --
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39 1 MEMBER KIRCHNER: No, don't go on yet, 2 Jenise.
3 MS. THOMPSON: Okay.
4 MEMBER KIRCHNER: This is Walt. I'm 5 sorry. Just calibrate us who are not geologists --
6 and you're speaking in a different language. So it's 7 less than 15,000 years for the dark blue on this 8 particular slide. Should that be of concern and what 9 concerns -- what's the take-away from this? It seems 10 like this is a very active site area, this Eastern 11 Snake River Plain, so for the general public what does 12 a geologist -- what's the take-away from this slide?
13 MS. THOMPSON: So I think one of the key 14 take-aways here is that in looking at a source like 15 the Eastern Snake River Plain it's not going to come 16 down to just looking at what the most recent age of 17 the basalt is. It's also going to be looking at the 18 current conditions within this system, the 19 tectonomagmatic model, understanding what if anything 20 is driving volcanism in this particular area and are 21 the conditions still in existence for this particular 22 source for there to be another eruption comparable to 23 what we see in the geologic record that's been 24 preserved for this location.
25 So it's not a matter of it's a 2,000-year-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 1 old lava flow time to panic. It's a matter of yes, 2 there's a 2,000-year-old lava flow. There are also 3 very old -- over 100,000-year-old lava flows out here 4 and looking at the specific conditions in which there 5 could be the potential for a future eruption in that 6 particular location or a future vent opening with an 7 associated lava flow or other volcanic hazard 8 associated with it.
9 But it's something to be aware of, but 10 it's also something that's going to require some 11 additional information to understand the conditions 12 for the specific site and also looking at the specific 13 location of the site. So a site that's going to be 14 located -- and I can't remember who provided the 15 comment earlier, but looking at moving up slope. That 16 is one consideration that can be made in looking at 17 sites in this particular area because in general we're 18 not going to see lava flows overtopping large 19 topographic barriers.
20 They're not going to be flowing uphill for 21 the most part. That would be highly irregular. So 22 looking at where there are areas where selecting a 23 site on a localized topographic high may be a very 24 prudent decision to make early in the siting process.
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41 1 here and it's going to depend on those site-specific 2 conditions and the selected location of that site and 3 the basis for the tectonomagmatic model that's 4 informing those hazard decisions for the applicant as 5 they develop their volcanic hazards assessment.
6 CHAIRMAN REMPE: Jenise, this Joy. And I 7 think this is a question I brought a while ago when 8 you first presented to us, but in the case of the 9 Idaho site -- there are a lot of facilities that are 10 within, I would think -- or at least more than one 11 within that 35-mile radius, not only existing, that 12 were built many years ago, but also ones that are 13 being proposed.
14 And so when you look at the hazards 15 associated with such an event -- even by the time the 16 Carbon Free nuclear power plant is built there might 17 be other facilities affected. So you're kind of 18 looking at not only the multiple units within the 19 Carbon Free plant, but there are also facilities that 20 that might be affected. And is that considered? I 21 kind of scanned through the Reg Guide and it didn't 22 explicitly call that out and I'm just wondering --
23 maybe I missed it, or how will the staff -- what will 24 trigger everybody thinking about don't just look at 25 this particular reactor or plant?
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42 1 MS. THOMPSON: So within the safety 2 reviews for new reactor licensing we do have 3 consideration of other nearby facilities, and that's 4 accomplished by our Manmade Hazards Team. And so the 5 concerns related to events that would impact other 6 nearby facilities would fall under their review. And 7 this is maybe a place where looking at the final INL 8 site-wide PVHA report can give our manmade hazard 9 reviewers some additional information of potential 10 hazards at those other locations that may then impact 11 the site that's coming in for review in a license 12 application, but that's something that would be 13 accomplished by Manmade Hazards Team.
14 CHAIRMAN REMPE: Okay. And the fact that 15 they may have not followed the latest guidance on 16 volcanic hazards because they were built a lot of 17 years ago and the response team was responding to all 18 of the common-cause failures associated with a seismic 19 event might be something that needs to be considered 20 more carefully at that site. Anyway, thank you.
21 MS. THOMPSON: You're welcome.
22 MEMBER MARTIN: Well, also to add the CFPP 23 is pretty unique, right, because it's a case where a 24 performance period is being sited on a DOE site and 25 the NRC has the authority. And again that's been 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
43 1 negotiated between DOE and NRC. I'm not sure I've 2 heard of another situation where that has occurred.
3 So I would imagine at this point DOE's kind of hands-4 off. They've managed their situation. And if there's 5 any new hazard created by CFPP I'm sure they'll be 6 assessing their reactors.
7 CHAIRMAN REMPE: The reality of the event 8 is there's a response team of the site that will have 9 to deal with all of it before anything can come from 10 other communities if you had to do something.
11 MEMBER MARTIN: (Audio interference) to 12 speak from my experience on DOE, a DOE -- a planned 13 DOE framework and not a reactor. Volcanic hazards is 14 part of hazards, the broader holistic hazards 15 analysis. And DOE's framework probably doesn't go to 16 the extent that's being presented here today, but it's 17 certainly within the safety basis of what they do and 18 how they review safety basis -- safety cases on the 19 site.
20 So what I find particularly useful is this 21 interaction between NRC and DOE making some effort to 22 get on the same page. Because clearly at Idaho 23 they've been thinking about this for quite some time.
24 And most commercial sites aren't impact, but I think 25 this is -- in my estimation with experience with DOE, 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 1 I like DOE's approach to hazard analysis in general.
2 And when I see you all talking to each other and 3 finding some common ground and working together and 4 shaping your analysis I think that's really the best 5 approach.
6 But I just wanted to really throw out the 7 fact that the CFPP is a unique scenario where DOE has 8 obviously stepped off and just said, okay, all the 9 work NRC's done for the last decade, we recognize that 10 and accept that and authority to (audio interference),
11 things like this.
12 MR. BENNER: Yes, I think I'm going to 13 partition that a little bit, Chair Rempe. So we have 14 -- we will have an application before us for an NRC 15 license. So we'll -- I think (audio interference) the 16 benefit here -- the downside here is yes, there might 17 be some additional hazard here. The benefit is we 18 have a federal partner who we can leverage their 19 experience and their information, but we'll have to 20 make the decision about CFPP and make -- render 21 judgment about the hazards.
22 And like Jenise said, there are two parts:
23 There's the pure volcanic hazards on that site and 24 then there's another part of there's a bunch of other 25 facilities there that could present hazards. I think 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
45 1 what you're asking is what I would call sort of the 2 second order effect of you have the volcanic hazard, 3 it has an impact on those other facilities, how is 4 that factored in our hazard analysis? And I can't 5 speak definitively about that, but I think we likely 6 -- (audio interference) experience we do do some 7 bounding assessment of those manmade hazards.
8 Now I don't know if we (audio 9 interference) it back to what was the cause of say a 10 train car exploding, right? We just say okay, a train 11 car could explode. What would be the hazard on the 12 facility? So that's one piece.
13 Now the other piece of -- is DOE looking 14 at the existing facility such that once this plant is 15 licensed it presents a manmade external hazard to 16 those facilities? I can't speak to that. I would 17 tend to think they would do some amount of assessment 18 on that, but I can't speak to their process for those 19 facilities.
20 CHAIRMAN REMPE: Again, I just wanted to 21 (audio interference) on the record again and you guys 22 could think about it, but one could have a vision of 23 a lava flow and a lot of dust that affects a lot of 24 facilities at once and everybody's trying to respond 25 to it. But of course it's very a low frequency of 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
46 1 that. I'm not worried about it and all that, but I 2 just think people need to think about it.
3 MR. BENNER: Right. And our license, 4 they'll have to demonstrate both from a safety 5 standpoint and from an emergency preparedness 6 standpoint how they're going to do things. Now how 7 much they would intend to leverage some close-by DOE 8 resources, that I'm not sure of, and we might not see 9 that until we get the application.
10 CHAIRMAN REMPE: Something to think about.
11 Anyway I raise the point.
12 (Laughter.)
13 MEMBER MARTIN: Since you bring up the 14 subject, DOE's hazard analysis approaches begin very 15 holistically with hazardous materials and energy 16 sources from everywhere. To your specific question 17 about hazards from other facilities, whether they are 18 the consequence of the first hazard, whether volcanic 19 or earthquake or plane, that is addressed in their 20 framework.
21 Now I guess what I have yet to see; and I 22 wasn't expecting this in this presentation, is what is 23 the NRC's approach to -- really to entry into hazard 24 analysis, whether it's this or looking at flooding or 25 earthquake? Is there a holistic hazards analysis that 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
47 1 at least at a high level reviews the site, the 2 environment, and looks at what are the hazardous 3 materials, what are the energy sources, what are you 4 neighbors doing, and incorporate it into a singular 5 document, and then from that initial assessment 6 potentially enters into volcanic or whatever type 7 hazards.
8 I think that's more of a question for you, 9 Eric.
10 MR. BENNER: Yes, and when you say a 11 singular document, all of those analyses are contained 12 in our SER for a particular site, so it should 13 integrate that (audio interference).
14 MEMBER MARTIN: But not necessarily a --
15 like it's a high-level document. I see it scatters --
16 MR. BENNER: Yes.
17 MEMBER MARTIN: -- with the detail, but it 18 definitely seems to be that there is an entry-level 19 exercise that maybe they screened out -- if you're 20 somewhere (audio interference) volcanos, what would be 21 the process to screen out (audio interference) this 22 exercise? If you had a holistic hazards analysis you 23 could go through and go, well, okay, I've considered 24 all these possibilities. I know (audio interference) 25 an earlier slide to (audio interference) numerical 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
48 1 values and likelihoods and such into it. At some 2 point you would want to say, all right, that hazard 3 isn't significant in this particular region, so would 4 not go down this path. How does that --
5 MR. BENNER: Well, we do in the Reg Guide.
6 There are some screening kick-outs, so I think you 7 have to at least start, right? And this is some of 8 the discussion we've had with industry of can you just 9 start by say the NRC screening out lots of things and 10 then the applicant's leveraging that?
11 And I think we took the approach that you 12 at least have to start looking at all these hazards 13 and then you might be able to quickly screen out --
14 but we do -- some of might -- well if we're talking 15 like the semantics of -- yes, you still have to look 16 at -- at least take the first step for each of the 17 hazards. But then you maybe quickly exit instead of 18 -- right, your first step is what hazards are 19 applicable to my site? And then only look at those.
20 I think we get to the same place. It's just -- right, 21 particularly when you look --
22 MEMBER MARTIN: Particularly a letter --
23 I think a letter approach --
24 MR. BENNER: Yes.
25 MEMBER MARTIN: -- where you (audio 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
49 1 interference) --
2 MR. BENNER: Yes.
3 MEMBER MARTIN: -- with energy sources and 4 materials. And then you go, all right, that works me 5 into these other ones. But that's obviously not the 6 way the framework --
7 MR. BENNER: Yes, I just think the 8 construct is that -- I think -- like I said, I think 9 you get to the same place. I just think it's sort of 10 the order of the (audio interference).
11 MEMBER MARTIN: I (audio interference),
12 but I think you do, but I think it's a little bit 13 harder to understand from an applicant standpoint --
14 MR. BENNER: Okay.
15 MEMBER MARTIN: -- because the entry is --
16 (Simultaneous speaking.)
17 MEMBER MARTIN: And it would be nice if 18 there was one overarching type process that then gets 19 you into the level --
20 (Simultaneous speaking.)
21 (Laughter.)
22 MR. BENNER: I'm going to link to the 23 topic I'll be talking about this afternoon because the 24 Committee gave us similar feedback on something from 25 Digital I&C. And basically I'm going to paraphrase.
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50 1 So like how does all this fit together, right? We 2 don't understand how the -- okay. So we ended up 3 doing a presentation for the Committee that had a 4 graphic that showed how it all fit together, and it 5 was interactive, right, the road map. And part of the 6 driver for that was, I think the Committee said, hey, 7 you're going to have a bunch of new applicants. How 8 do you make this clearer for them?
9 So I'm going to take from this meeting 10 that we would consider a similar approach for our 11 external and manmade hazards activities. Not 12 necessarily to make the presentation, but can we look 13 at ways that we can come up with tools to communicate 14 and make it clearer for potential applicants?
15 MEMBER BROWN: It's nice to see that the 16 I&C world is --
17 MR. BENNER: Having an influence on the 18 rest of society?
19 (Laughter.)
20 MEMBER BROWN: (Audio interference) make 21 clear what they're doing.
22 MR. BENNER: Okay. Good.
23 (Simultaneous speaking.)
24 CHAIRMAN REMPE: We both got it. Probably 25 we're off topic, but thank you for considering it.
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51 1 (Laughter.)
2 MR. BENNER: Hey, let's go back to Geneva 3 on that.
4 CHAIRMAN REMPE: Scott, do you need a 5 question, sir?
6 MR. MOORE: Yeah, just a point of 7 information. I don't know what --
8 (Audio interference.)
9 CHAIRMAN REMPE: Scott, we have -- you 10 need to get up closer to the places that are around 11 the room. I didn't try your spot, I tried other 12 spots. Sorry.
13 MR. MOORE: This is just a point of 14 information. And I don't know what hazards analysis 15 or risk analysis was done for these. But DOE has two 16 NRC licenses at INL. One of them's active, one of 17 them's not active.
18 The active one is -- they're both for 19 waste -- one of them is the TMI-2 fuel debris license, 20 and it's a specific NRC license. And the other is 21 called a license but it's not built. It's the Idaho 22 Spent Fuel Facility.
23 So, NRC has licenses just for that item.
24 CHAIRMAN REMPE: Well, actually, I think 25 Lawrence Berkeley, there was an effort years ago where 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 1 NRC would license DOE facilities. And there's one at 2 Lawrence Berkeley and one other place that I can't 3 remember. But it's not typical. Yeah, it's not 4 typical.
5 (Simultaneous speaking.)
6 CHAIRMAN REMPE: Yeah, it's not.
7 MEMBER MARCH-LEUBA: Also, for example, is 8 Columbia Power Station is an example.
9 MR. MOORE: Yes.
10 MEMBER MARCH-LEUBA: But that one is 100 11 percent privately owned, whereas the CFPP has a lot of 12 relations with DOE for starters.
13 PARTICIPANT: Is that actually onsite?
14 MEMBER MARCH-LEUBA: Yes.
15 (Simultaneous speaking.)
16 CHAIRMAN REMPE: Jose, you can actually, 17 I tried your spot. It works and you don't need to 18 move. It was Scott that was so far away.
19 But, yeah, for those out on the internet 20 we've had some IT issues today. Actually, it was 21 working great today thanks to Comcast, whoever is on 22 it now.
23 Anyway, go ahead, please.
24 MS. THOMPSON: Are we ready to -- I heard 25 talking in the background.
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53 1 MEMBER BROWN: It's Charlie Brown.
2 Am I not loud enough?
3 MS. THOMPSON: No. I can barely hear you.
4 MEMBER BROWN: Okay. That's unusual.
5 CHAIRMAN REMPE: Just speak louder.
6 MEMBER BROWN: Am I closer now?
7 MS. THOMPSON: Yes.
8 MEMBER BROWN: Okay. No, I guess my 9 question is TerraPower is a new advanced reactor 10 design. Why, why do they have a topical report and 11 they're going to put a new reactor like this?
12 Does this complicate NRC's ability to 13 evaluate that, all the rest of this stuff that they're 14 bringing to the table as well as now have to deal with 15 the volcanic location that they seem to be evaluating?
16 MR. BENNER: Well, I'll give the general 17 answer and Jenise can supplement.
18 I mean, any, any applicant can come to us.
19 I'll partition this into two parts.
20 Regarding the siting, they can propose any 21 site they wish. And then we just have to work with 22 that applicant to see if the hazards, you know, 23 indicative to that site can be managed.
24 The idea of a topical in the, in the 25 advanced reactor framework a lot of advanced reactors, 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 1 because we don't have -- we've, we've been asked, hey, 2 can you spec measure these so applicants can get 3 certainty on certain things? And we don't overall 4 segment for these. We have our licensing processes.
5 But, you can use topical to get some level of 6 certainty in a specific area that what you're doing 7 seems to be appropriate to the staff.
8 So, again, that's a choice on their part.
9 They put all this in the application. I think it's 10 pretty common for all the advanced reactors applicants 11 that for certain parts of the review that they either 12 want to try a new approach or know we're going to be 13 challenging.
14 They oftentimes lead with a topical to 15 sort of get a head-start and get the feedback from the 16 staff on, on, you know, the staff's position. It does 17 make it somewhat challenging for many of these 18 reviews. So, those aspects are going on in parallel.
19 We have reviews where the topical report 20 is being reviewed at the same time as the actual 21 licensing review. We have to work hard to make sure 22 there's the appropriate intersection of those two 23 reviews.
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55 1 to mention.
2 MS. THOMPSON: No. I think you covered 3 it.
4 It's just a different approach to 5 providing their volcanic hazards assessment 6 information. And it's an approach that's allowed 7 within the regulatory process. And so, we'll review 8 that topical report just as we would if that 9 information had been included in the license 10 application directly.
11 So, it doesn't really change our review 12 approach, it just changes a little bit the, the 13 timeline for it, and the interactions or the interface 14 between that topical report review and the license 15 application review.
16 All right. So, we'll move a little bit to 17 the east, so move to the Eastern Snake River Plain.
18 I know the other source of volcanic hazards that we've 19 had a lot of questions and inquiry about in the past 20 has been the Yellowstone Caldera.
21 So, we'll go to the next slide, please, 22 Barb.
23 And I'm showing this picture not to be 24 alarmist. This is not -- the shaded areas are not 25 reflective of a continuous ash layer across the United 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
56 1 States. These are just showing the shapes that 2 encompass the mappable or the maps deposits for these 3 three past historical Yellowstone eruptive events.
4 So, we have the largest event is the most 5 recent at a 630,000 year old eruption from Yellowstone 6 that resulted in the Lava Creek tephra ash bed. The 7 teardrop shape in the middle is the smallest volume or 8 the smallest area. It's a 1.3 million year old 9 eruption. And then that intermediate shape in the 10 middle is the Huckleberry Ridge at 2.1 million years.
11 And what I wanted to emphasize with 12 respect to Yellowstone, I know there's been a lot of 13 question about it. I know there has been, you know, 14 T.V. specials, things like that about the Yellowstone 15 Caldera and super eruption. And in looking at 16 potential sources like Yellowstone, this is where 17 something like the tectonomagmatic model and looking 18 at the wide amount of research and information on the 19 current state of these volcanic, these forces of 20 volcanic hazards, these volcanoes, these calderas, 21 becomes a very important component to both the 22 development of the volcanic hazards assessment for a 23 site that may need to consider a hazard originating 24 from Yellowstone. And it's also going to inform the 25 staff's review of these potential hazards.
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57 1 So, looking at this, it's not a you must 2 consider hazards from Yellowstone ash deposits, it is 3 a future Yellowstone, or is the current state of the 4 Yellowstone system consistent with this type of 5 eruption that we see preserved in the geologic record.
6 So, that's the key thing that I want to 7 emphasize with particularly tephra hazards coming from 8 Yellowstone.
9 And I'm going to go to the next slide 10 which is also still going to talking about 11 Yellowstone.
12 And considering the tectonomagmatic model 13 and how -- what are the driving factors that are 14 influencing the potential for volcanism in these 15 active systems, and a lot of that is going to come 16 down to monitoring of these volcanoes and these 17 volcanic forces.
18 So, this is, again, a map from the 19 Yellowstone Volcano Observatory. Each of the symbols 20 on the map is showing a different type of 21 instrumentation that that volcano observatory is using 22 to actively monitor this particular volcanic source.
23 And so, this is something that the USGS 24 does an exceptional job of with respect to monitoring 25 of these volcanoes within their observatory system.
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58 1 And some of the instrumentation that's installed just 2 here at the Yellowstone system is these seismometers.
3 They are literally taking the temperature of this 4 caldera, GPS, SCAT, cameras.
5 If you'd like to go online to the 6 observatory site you can get online and see their 7 webcams and they'll show you the current state of the 8 calderas on a webcam for you, and also tiltmeters.
9 So, these are heavily monitored systems so 10 that if in these volcanic hazards assessments there is 11 a need to consider a volcanic hazard originating from 12 one of these closely-monitored systems and/or to 13 implement a mitigating action in the event of a 14 volcanic hazard emanating from this particular 15 resource there's going to be a fair amount of 16 information available.
17 The USGS would be responsible for issuing 18 that alert, and then considering whether there's 19 adequate warning time, could potentially all be 20 factors that we'll be looking at in the reviews of 21 these volcanic hazards assessments.
22 And so, that's kind of what I wanted to 23 emphasize with looking at both of these two systems 24 here with the Eastern Snake River Plain and 25 Yellowstone. And we'll see the information as we come 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 1 to it. But in looking at the volcanic hazards 2 assessments that are being performed, understanding 3 the tectonomagmatic model what is currently driving 4 volcanism is going to be a very important component of 5 our review and of the development of the volcanic 6 hazards assessment.
7 And so, looking at some of these potential 8 sources we'll go to the next slide. And now I'm going 9 to talk a little bit about the potential hazards and 10 what those potential hazards may be in looking at 11 effects on a nuclear facility.
12 So, this is kind of an exhaustive list of 13 potential hazards. You can refer to the write-up in 14 Reg Guide 4.26 or the February 2020 presentation where 15 I went into a lot of different volcanic hazards in 16 much more detail. But I'm very briefly going to touch 17 on three specific hazards.
18 And those are tephra fall, lava flow, and 19 new vent opening. And with new vent opening would 20 come proximal hazards. And those are hazards that are 21 going to be spatially limited to a very close 22 proximity around that particular vent opening.
23 So, going on to tephra fall, you saw the 24 map of the Yellowstone ash spreads. The tephra is a 25 volcanic hazard that can be both a very localized 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
60 1 phenomenon, or it can travel very long distances. And 2 with that there can be a wide range in spherical 3 sizes, can be a wide range in thicknesses, and also 4 looking at deposit density.
5 So, the picture shown here, this lighter-6 colored material on the surface of the earth, this is 7 a tephra blanket of the two full features. This is, 8 oh, just over a 2,000 year old tephra blanket. And 9 you can see that it's not, this is not a thick 10 sequence of volcanic ash. This is, you know, within 11 probably 100 yards of the feature itself. But this is 12 not a very thick sequence, but it is still prevalent 13 out on the plains. And it almost looks to me like 14 somebody spilled glitter sometimes.
15 What we're looking at in terms of what 16 this would mean as a hazard to a nuclear facility, 17 there may be potential for issues with air intakes on 18 related structures.
19 Also, looking at if there is tephra 20 deposition or accumulation in the switchyard. Is 21 there any potential or need to address removing that 22 tephra before there are concerns with things like 23 arcing, because things like volcanic ash, this is rock 24 material so it's not, you know, like paper or 25 something you get in your fireplace.
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61 1 So, we're looking at things that have a 2 wide range of particle sizes. And with that comes a 3 wide range of potential impacts on the nuclear asset 4 at the particular site.
5 So, as we look ahead to how are we going 6 to review not just what the hazard is going to be at 7 that site, or what the applicant has determined the 8 hazard from that ash fall to be at the site, you know, 9 looking at things like deposit density, thickness of 10 that deposit, we're also going to be looking at for 11 that particular design of reactor what are the 12 potentially affected SSEs from that volcanic ash?
13 Is this an enclosed system that doesn't 14 have air intakes that would be impacted by tephra?
15 Or, are there safety-related SSEs that 16 rely on air intake to perform their safety functions?
17 And, again, this is where working with our 18 systems engineering counterparts is going to play an 19 important role in the review, not just to the volcanic 20 hazards but the effect on the facility as well. And 21 if there is a potential effect on those SSEs, ensuring 22 that there is adequate warning time to implement 23 whatever mitigating action is necessary to ensure the 24 continued performance of that SSE will also fall 25 within the scope of the licensing review that we're 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
62 1 expecting to perform.
2 Moving on to the next slide and lava flow 3 hazards.
4 We looked at the map from the Eastern 5 Snake River Plain that is from the Hell's Half Acre 6 lava field. So, this is just to the east of the INL 7 property boundary. Hopefully, everyone can see the 8 person up on this low lobe.
9 And lava flows, when we're talking about 10 these we're looking at dense, hot, these have a very 11 high heat capacity comparable to metals. So, these in 12 terms of hazard could, if they reach a nuclear 13 facility, could pose a massive problem.
14 But in looking at the volcanic hazards 15 assessments and preparing for these reviews, some of 16 the things that are going to factor into that review 17 and the determination of whether this hazard is going 18 to impact the site are going to be things like the 19 distance traveled from the source to the site.
20 And it is the volume of flow and the 21 viscosity of that flow. Does that flow have the right 22 properties and the right topography to reach that 23 particular site when erupted from a specific source.
24 And so, we're going to be looking at a lot 25 of very local, locally dependent conditions that could 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 1 impact where that flow could travel and whether that 2 flow could result in some kind of adverse effect on a 3 nuclear facility. But in general, as I said before, 4 we're going to see that flow is generally going to be 5 governed by topography.
6 You can imagine, I took this picture 7 standing kind of in the lower basin area, and this 8 flow is the end of that particular lobe. So, that's 9 kind of the toe of it where it stops.
10 But you could imagine that if there was a 11 flow of sufficient volume that flowed into this lower, 12 you know, localized basin where I took this photo, 13 that if there is a continued influx of lava flow it, 14 it could have the potential to overtop this more 15 localized high point where the person is standing.
16 But, again, that's going to be a very site-specific 17 decision looking at site topography, looking at 18 location of the vent from which the lava is erupting, 19 and looking also at the conditions of the lava as 20 well.
21 So, looking at flow hazards there's, 22 again, just like tephra, there are a lot of different 23 components that will come into play when considering 24 lava flow. But in general, on the Eastern Snake River 25 Plain you'll see that topography is likely to be king.
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64 1 And then we'll move into our, the last 2 example hazard for today which is the new vent opening 3 and the associated proximal hazards. We'll go on to 4 slide 16.
5 This, there we go.
6 So, the photo here is showing the Kings 7 Bowl feature, which is a just over 2,000 year old new 8 vent. It opened just north of the Wapi lava field in 9 the southern part of the Eastern Snake River Plain, so 10 it's out of the INL property here.
11 You can see some people on the left side 12 of the feature right up on the ridge line there. It 13 gives you a feel for the size of this particular 14 feature.
15 The photo is taken looking to the north.
16 So, to the right side or the east, that's where that 17 tephra blanket picture was taken, which is consistent 18 with the prevailing winds on the Eastern Snake River 19 Plain, coming from west to east or, in this photo, 20 left to right. So, you see the tephra blanket on the 21 eastern side of the feature here, which would be one 22 of those proximal hazards to be considered.
23 This new vent opening also had a lava lake 24 that formed just to the western side, so past where 25 the people are standing. And those low, very low 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
65 1 hills along the horizon are roughly representative of 2 the end of that, the extent of that lava lake.
3 And that lava lake, that surface, that now 4 hardened lava surface preserves some evidence of these 5 proximal hazards that we see.
6 But what I want you to take away from this 7 is that new vent opening is not going to be a 8 surprise. These are going to be events that are 9 preceded by increased activity because, as you can 10 imagine, as a magma body comes up from the depths in 11 the surface of the earth towards the surface it's a 12 very disruptive process. And all of the overlying 13 rock is going to have to accommodate that magma body 14 flowing up towards the surface.
15 And what we may see is surface deformation 16 along with that increased seismic activity. And it's 17 also important to note that it's possible for these 18 magma bodies, these erupted sites to eventually stall 19 in the subsurface and not become a surface, a new vent 20 opening on the surface. But if that were to occur, 21 you would still see that increase in seismic activity, 22 and potentially see also surface deformation, 23 depending on the depth at which that magma body stalls 24 in the subsurface.
25 So, we'll go the next slide.
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66 1 As I mentioned before, the lava lake still 2 shows some evidence of volcanic ballistics.
3 So, it hasn't changed on my screen yet.
4 Maybe it will change.
5 There we go.
6 So, on the left-hand size -- and I 7 apologize, there's no scale on this slide, but I could 8 stick my, the toe of my boot in this hole here on the 9 left-hand side. And what happens here is you have the 10 lava lake essentially starting to pool and form a 11 crust along that surface. And as continued eruption 12 occurs, lava is erupted and those smaller globs of 13 material break through that surface and results in the 14 small hole in the center of this photo on the left.
15 And as I mentioned before, also with this 16 another proximal hazard is going to be looking at 17 things like tension cracks or fissures. And these are 18 going to be features that open up generally on either 19 side of the new vents to accommodate that magma body 20 rising towards the surface. And this is how the earth 21 is accommodating that additional volume coming up and 22 potentially erupting to the surface.
23 And you can see a person kind of in the 24 top center of the photos here. This is roughly about 25 a meter wide. And then it's very, very deep. And it 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 1 runs several kilometers north to south. And it runs 2 parallel to that new vent opening, both on the east 3 side and the west side, and accommodating that volume 4 of magma rising to the surface and then erupting 5 actually itself.
6 So, those are just three of the hazards 7 that may need to be considered in the course of these 8 volcanic assessments that we're starting to review.
9 Like I said, it's not exhaustive, so if other volcanic 10 hazards are streaming in from other volcanic sources, 11 we are also prepared to review these. But these, I 12 think, are realistic, realistic hazards that we may be 13 expected to review in the course of these volcanic 14 hazards assessments.
15 So, we'll continue on to slide 18, please.
16 So, I had promised that we would talk 17 about numerical modeling. So, here we are.
18 And in looking at what would be the 19 magnitude of the hazard or the probability of those 20 hazards erupting or reaching a site, what we are 21 expecting to see from most of these applicants 22 performing volcanic hazards assessments is a reliance 23 on numerical modeling.
24 Again, looking at Reg Guide 4.26, we've 25 not endorsed a specific program or another because 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 1 there are many different programs out there, each with 2 their own merit and each with their own applicability 3 to certain sites and what your desired outcome will 4 be.
5 So, our focus has been on the programs 6 that we know applicants are planning to use, and 7 focusing on understanding those models, and the 8 development of those models, and how those models are 9 being applied for these particular sites, so that when 10 those models are presented as part of either a topical 11 report or a license application that we have built an 12 understanding of them so that we can better fulfill 13 our review role in looking at the model support that's 14 being provided, and the justification for the use one 15 code for this particular license application.
16 So, for TerraPower we know that they're 17 using AshPlume and PVHA_YM. Both of these were 18 developed through CNWRA as part of the Yucca Mountain 19 licensing review. AshPlume is a code that's modeling 20 atmospheric dispersion and deposition of tephra. And 21 PVHA_YM is estimating the probability of a volcanic 22 event occurring within an affected area using a kernel 23 density, or using kernel density estimates.
24 So, those are the two codes we know that 25 TerraPower is using.
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69 1 And for the INL PVHA and the Carbon Free 2 Power Project, the CFPP application, we know that 3 they're choosing to use Tephra2 and MOLASSES as part 4 of their numerical modeling. And Tephra2 and MOLASSES 5 are both open-source codes developed by a team of 6 researchers and faculty from the University of South 7 Florida.
8 Tephra2 models tephra accumulation at 9 locations around a source volcano.
10 And MOLASSES is used to estimate the area 11 inundated by lava flows for a pre-loaded digital 12 elevation model.
13 And so, this is where our primary skills 14 focus on volcanic hazard modeling has been to support 15 these models. Again, it's going to be up to the 16 applicant to provide the justification for the use of 17 those models and the applicability for their use at 18 their selected sites, because we just can't consider 19 every single model that's available and out there and 20 build capability for the staff to functionally use 21 each of those models, or determine which one is better 22 than another. Because it is, to some level, going to 23 be a very site-specific consideration.
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70 1 with using in the performance of their volcanic 2 hazards assessment.
3 So, I'll pause because I'm expecting maybe 4 a question or two here.
5 MEMBER KIRCHNER: Jenise, this is Walt 6 Kirchner.
7 Could you talk a little further about the 8 D&D of these codes? Are they actively -- have they 9 been benchmarked in any way against Mount St. Helens, 10 or in the case of MOLASSES, against lava flows in 11 Hawaii, et cetera?
12 Is there any, it is all based on historic 13 evidence or are they actually using active volcanic 14 activity for benchmarking?
15 MS. THOMPSON: So, I know that AshPlume 16 and PVHA_YM both went through the nuclear validation 17 and verification in support of the Yucca Mountain 18 Review.
19 And I know just based on the literature 20 that we have seen a lot of literature published in 21 using Tephra2 and MOLASSES against known eruptions, 22 and looking at those.
23 I would refer you back to -- I'm trying to 24 think -- I think it was the February 2020 presentation 25 I gave. I think we went through an example from one 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 1 of these. I don't remember exactly what I had before 2 that.
3 But that, that's an excellent question.
4 And that's something that we're seeing these codes 5 being used in the literature. And that's something 6 that will be important in our review for the 7 justification for the use of those particular codes.
8 MEMBER KIRCHNER: Okay. Thank you. I'll 9 go back and look at your --
10 MS. THOMPSON: I'm just looking back at --
11 MEMBER KIRCHNER: -- your 2020 12 presentation.
13 Okay, thank you.
14 MS. THOMPSON: Yeah. I would particularly 15 look at, I would particularly look at slides 31 and 32 16 from that presentation which, how appropriate, the 17 example we used was from -- was three different codes 18 used to model the 1997 eruption at Soufriere Hills on 19 Montserrat. So, we've come full circle today.
20 MEMBER KIRCHNER: Okay.
21 MS. THOMPSON: All right. If there's no 22 other questions on this slide, I've just I think two 23 or three more slides to go.
24 So, we talked about, I talked about a lot 25 today of not just the Reg Guide and the process for 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 1 the outlines, but the ongoing activity action we have, 2 the potential forces of inputs that we talked about, 3 volcanic hazards, how they would be modeled to 4 determine what those maximum magnitude hazards would 5 be. And it's all to inform these future licensing 6 reviews.
7 So, we know that applicants in general are 8 following Reg Guide 4.26. There's been some minor 9 alterations, but I do think that the publication of 10 Reg Guide 4.26 was very timely, and that we're seeing 11 three different projects that are proceeding with the 12 process outlined in 4.26 for the performance of 13 volcanic hazards assessments.
14 So, that's giving us some confidence that 15 we were on the right track with issuing that Reg Guide 16 when we did. And now we're getting some important 17 lessons learned from the application of those Reg 18 Guides to actual projects over the last few years and 19 into the next couple years as we move into license 20 reviews for those, the uses of that approach for 21 performing a volcanic hazards assessment.
22 We're also, as I said, we're preparing for 23 the review of those numerical models, including being 24 ready to perform confirmatory calculations. But 25 that's something that we, as a staff, during the 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 1 course of our licensing reviews decide is necessary or 2 prudent to perform.
3 And we've also completed several site 4 visits. We've been out to the Eastern Snake River 5 Plain in support of INL PVHA work. And we've also 6 been out there for pre-app engagement with the CFPP 7 applicant. So, we've seen a lot of these features in 8 the field directly observable for us.
9 So that's, that's an important factor when 10 we're performing our review as well is having a clear 11 understanding of the scale, and scope, and proximity 12 of these features to other locations around the site 13 region and site vicinity.
14 And we expect as part of our licensing 15 review that we'll get out to the TerraPower site as 16 well in the future.
17 So, moving on to the next slide.
18 We're also, just to reiterate, as we look 19 toward particularly the effects of volcanic hazards on 20 SSEs at these, for these particular designs, whether 21 there is a need or a case need for mitigating actions 22 to improve that SSE performance. And with that, 23 looking at things like criteria for initiation.
24 Is there a need for monitoring or 25 additional monitoring if these systems are already 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 1 monitored?
2 What would be considered the practical 3 demonstration of these actions and activities as this 4 is where we may be looking to our hydrology 5 counterpart to have a lot of experience of looking at 6 the implementation of flood protection measures and 7 the possible implementation of those between the 8 notification of an impending event and the arrival of 9 the hazard at the site. So, we do have some 10 experience in the review of other hazards that may be 11 informing how we approach those volcanic hazards 12 assessments and those, the efficacy of those 13 mitigating actions in the future.
14 And then, also just to reiterate, we're 15 also looking at foundation and excavation plans and 16 how that may relate to foundation stability with our 17 geotechnical instructional engineering counterparts.
18 And also looking ahead for that geologic mapping 19 permit condition piece put into our, our staff 20 evaluation or our safety evaluation reports for these 21 permit or license applications, and how, if there are 22 any considerations beyond the normal considerations 23 that may need to be considered for siting in volcanic 24 terrains.
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75 1 you can kind of see that middle fractured layer in the 2 center. If that becomes your foundation level what, 3 if any, additional measures or actions need to be 4 taken to ensure foundation stability or excavation 5 stability?
6 So, we have a lot of cross-pollination 7 between not just our hazards staff but also the 8 engineering staff at the NRC so that we're prepared to 9 take a very holistic approach to these reviews, not 10 just looking at it from a geologic perspective, but 11 also incorporating all of these other engineering 12 considerations that we need to be aware in performing 13 these future licensing reviews.
14 So, we'll go the last slide here and just 15 kind of give you a snapshot of what's ahead for us.
16 As I mentioned before, the TerraPower 17 topical report review is ongoing. So, we'll be 18 completing that review in the next couple of months, 19 I believe.
20 We also are getting ready for the 21 acceptance and detailed technical reviews of both the 22 CFPP and TerraPower applications. So, we'll have 23 those on our plate as well.
24 And what we're planning to do as we move 25 forward with these licensing reviews and activities is 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 1 documenting our lessons learned. Because really what 2 we're, in addition to performing these licensing 3 reviews, we want to ensure that in the future Reg 4 Guide 4.26 continues to be a useful tool for 5 applicants considering siting in volcanic terrain, or 6 needing to consider volcanic hazards as part of their 7 license application process.
8 And so, making sure that what we learned 9 in our experiences, and what the applicants have 10 learned from using Reg Guide 4.26 to guide their 11 volcanic hazards assessments is something that we're 12 capturing and improving on in the future.
13 So, I'll just leave you a photo from 14 Craters of the Moon, this very steep slope called Blue 15 Dragon Flow, if you hit the light just right sometimes 16 it iridesces a little blue for you. And this is just 17 to, again, emphasize for some of these locations 18 topography will be king. Because this flow came in 19 from the horizon area, went around the local 20 topographic highs, and into the path of least 21 resistance, this lower basin here.
22 So, with that, I think I've left a half 23 hour2.662037e-4 days <br />0.00639 hours <br />3.80291e-5 weeks <br />8.7515e-6 months <br /> for questions. So, I will stop talking now.
24 Thank you.
25 DR. BLEY: Jenise, Dennis Bley.
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77 1 MS. THOMPSON: Yes.
2 DR. BLEY: Will you be bringing the 3 TerraPower topical to the committee?
4 And if so, when do you expect that to come 5 to the committee?
6 MS. THOMPSON: I will defer that to the 7 project manager. I believe one of them might be 8 online, and they would be able to speak to the 9 schedule better than I am. Or, yeah.
10 So, Stephanie just raised her hand. She's 11 the PM for that topical report.
12 MEMBER KIRCHNER: Jenise, this is Walt 13 Kirchner. I have some information on this.
14 And I suspect, Dennis, -- well, first I 15 want to tell everyone on the committee that the White 16 Paper from CFPP and the staff's review of that 17 approach are both on our SharePoint site for today's 18 meeting, as well as the TerraPower topical report's 19 there.
20 So, you, if you want to start taking a 21 look at it, it's available.
22 Second, I believe from my scholarly 23 information I have is we may be looking at the 24 TerraPower topical report in the May time frame of 25 next calendar year.
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78 1 MS. THOMPSON: Yeah. And I see that 2 Stephanie Devlin-Gill, she's the PM for the TerraPower 3 topical report, has her hand raised.
4 So, Stephanie, did you want to chime in 5 with more?
6 MEMBER KIRCHNER: Yeah.
7 MS. DEVLIN-GILL: So, well, I don't 8 actually -- Hello, everyone. Stephanie Devlin-Gill, 9 senior project manager for TerraPower.
10 I don't have anything more to add. That's 11 right now on our schedule, yes. We think subcommittee 12 in something of the May time frame. But we are in the 13 early stages of the review. So, that may change with 14 time, but that's the current schedule.
15 So, thank you.
16 MEMBER KIRCHNER: Members, further 17 questions?
18 Go ahead, Vicki.
19 MEMBER BIER: First, can you hear me from 20 where I am?
21 DR. BLEY: You're a little soft, but yes.
22 MEMBER BIER: I'll come around to a 23 microphone. Sorry.
24 Hi. Can you hear me now?
25 MS. THOMPSON: Yes.
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79 1 MEMBER BIER: Okay, thank you.
2 I was curious about what is the state of 3 the art on forecasting of volcanoes?
4 And would we expect something similar to 5 what's done for hurricanes where if there's a 6 significant risk identified we might shut the plant 7 down preventably?
8 And has anybody thought about that or 9 looked into it?
10 MS. THOMPSON: So, I don't know if you 11 would call it forecasting. But the U.S. Geological 12 Survey does keep a very close watch on all of the 13 volcanoes that are included in their Volcano 14 Observatory Program. They operate I believe it's five 15 Volcano Observatories around the U.S. And that would 16 be the authority that would issue any kind of 17 notification of an impending volcanic event.
18 Whether that would rise to the level of 19 needing to shut down the facility, I think it's going 20 to depend on what the potential hazard would be for 21 that particular location, and not something that we 22 would review as part of the application. But it's not 23 something that we would -- it's not something I want 24 to speculate on right now because I wouldn't know what 25 the justification would be or what the particular 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 1 hazard would be from a hypothetical volcanic feature 2 that's going to result in a hazard impacting a nuclear 3 site.
4 So, that's something that we'll consider 5 going forward. But I don't believe that there's a --
6 it's not a forecast per se, but there is active 7 monitoring of these volcanoes in the United States by 8 the USGS.
9 MEMBER BIER: Okay. And just have an 10 additional comment.
11 I know that there has been a method to go 12 up, like, on small island nations, or whatever, where 13 you have to worry about when people evacuate, to kind 14 of -- it's essentially a formal expert opinion method, 15 you know, similar in a way to the seismic hazard 16 assessment but much less voluminous and elaborate, 17 something that you can do quickly.
18 And they have used that to decide on 19 evacuations in some circumstances. So, if people are 20 interested, I could forward links to that, or 21 whatever. But it's just something to consider going 22 forward how would those decisions be made.
23 DR. BLEY: Hey, Vicki, this is Dennis.
24 MEMBER BIER: Yes.
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81 1 but back when Mount St. Helens erupted, for about a 2 month before that there was a lot of very public 3 communications of the activity and changes and kind of 4 swelling of the earth under -- above that area. And 5 it was very thoroughly tracked and publicized.
6 MEMBER BIER: Yes. Thank you.
7 That's the extent of my comments.
8 MS. THOMPSON: Thank you.
9 MEMBER KIRCHNER: Members, other comments 10 or questions?
11 MEMBER DIMITRIJEVIC: Jenise.
12 MS. THOMPSON: Yes?
13 MEMBER KIRCHNER: Vesna, do you have any 14 questions?
15 MEMBER DIMITRIJEVIC: Yes.
16 Actually, I would like to ask, Jenise, do 17 you have a feeling, you know, because as a PRA person 18 I'm mostly interested in these numerical estimates, 19 and I have a feeling that those will be, you know, 20 very hard to come with any reasonable certainty.
21 So, do you have any feeling how work, 22 elaborate work is needed to come with this numerical 23 estimate for any applicant? How much work, you know, 24 has to be invested in get those numerical estimates?
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82 1 computational time for their modeling or?
2 MEMBER DIMITRIJEVIC: No, no. It means 3 what kind of basis that you collect. I mean, are we 4 talking here very work-intensive or, you know, because 5 that would -- that's not something that will be 6 available for the different areas; right? So, the 7 applicant will have to do that, his own study to cover 8 those numerical estimates.
9 MS. THOMPSON: So, I'm going to preface 10 this by saying that I think it's going to be up to the 11 individual applicant to determine the extent of the 12 numerical modeling they would like to perform.
13 There's no requirement in the Reg Guide 14 that an applicant needs to take a modeling-intensive 15 approach to determining their hazards. An applicant 16 could just as easily assume a maximum magnitude hazard 17 in their screening steps, and take a much more 18 deterministic approach of, okay, the thickest ash 19 layer that I've found is X number of meters. And they 20 can link it, assuming that will be the hazard at their 21 particular site without the need to do any additional 22 modeling.
23 And that would probably be the least 24 amount of effort to complete that. Whether it's the 25 most accurate reflection of the volcanic hazard for 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 1 that particular source and that particular site is 2 probably debatable. And that's where using a, using 3 an approach that would rely more on modeling may be 4 useful for, particularly if you're looking at SSE 5 performance and you don't want to be considering the 6 performance of SSEs under, you know, a 5-meter load of 7 ash. I'm just picking a number out of thin air there.
8 So, it can be as computationally time 9 consuming as an applicant desires it to be. There's, 10 I assume, my gut is telling me, that we'll probably 11 see somewhat of a middle ground where there is some 12 deterministic looking, screening of certain hazards 13 and then taking a modeling approach to determine, to 14 refine that hazard level for other hazards or other 15 potential -- or other sources of volcanic hazards.
16 But I, I wouldn't want to guess how much 17 time and effort it's taking.
18 MEMBER DIMITRIJEVIC: You said exactly 19 what I was, you know, hoping you would say. Because 20 you actually said a couple of times you guys support 21 numerical approach. But that's, you know, a lot of 22 times would be, you know, the much more productive to 23 combine with the deterministic approach, you know.
24 MS. THOMPSON: Yeah. And that's a good 25 clarification is in the development of Reg Guide 4.26 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 1 we wanted there to be flexibility. So, the option of 2 using numerical modeling is available. It's not a 3 requirement though.
4 So that having that flexibility I think is 5 important for applicants to be able to choose what's 6 best for the conditions at their site and their 7 selected design. And that's something that we're 8 seeing play out in these volcanic hazards assessments 9 that we expect to be reviewing.
10 MEMBER DIMITRIJEVIC: And so, basically in 11 your diagram that's acceptable, the condition is, you 12 know, flexible, right, what is acceptable?
13 MS. THOMPSON: Well, that's, that's 14 acceptable to the applicant to complete their 15 assessment. Acceptable to the NRC staff is something 16 that we would determine in the course of our review.
17 So that it's up to the applicant, if they 18 believe that their results should be earlier in the 19 volcanic hazards assessments process in that flow 20 chart is acceptable to take that off ramp and complete 21 their assessment, then it would be up to the applicant 22 to make the case for why that stopping the assessment 23 at that point is acceptable, and to justify that 24 conclusion and not proceeding further in the analysis.
25 MEMBER DIMITRIJEVIC: Right. And this is 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 1 where they can introduce risk-informed, you know, 2 principles like --
3 MS. THOMPSON: Exactly.
4 MEMBER DIMITRIJEVIC: -- like, for that 5 part of a -- if they determine that that's the only 6 hazard that can get to the site, then the only impact 7 would be on, let's say, switchyard, then, you know, 8 you don't need really volcano to use offsite power, 9 things like that. You know, you can do some 10 comparison with current risk and things like that, and 11 make a risk-informed decision.
12 That's how I always visualize this can be 13 done.
14 MS. THOMPSON: Exactly.
15 And that's correct, the intent of the Reg 16 Guide because in looking at volcanic hazards there's 17 a wide range of physical demands that could result on 18 the affected facility. And it would be impractical to 19 not consider a risk-informed approach to considering 20 such a wide range of potential effects on a facility.
21 It's not a one-size-fits-all approach for 22 volcanic hazards by any stretch because there are just 23 so many different physical characteristics that need 24 to be considered. And then potentially so many 25 different SSEs that may be impacted by whatever the 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 1 hazard may be.
2 MEMBER DIMITRIJEVIC: Okay, thank you.
3 MS. THOMPSON: Thank you.
4 MEMBER KIRCHNER: Members, I need to leave 5 time for public comment. And maybe this is a good 6 juncture to ask.
7 Anyone out there on the line, unmute 8 yourself, identify yourself, affiliation if 9 appropriate, and make your comment.
10 (No response.)
11 MEMBER KIRCHNER: Hearing no comments from 12 the public. One last time amongst the members, any 13 further comment?
14 MEMBER MARTIN: One more administrative.
15 Other hazards, external hazards, flooding 16 and earthquake, appear in the Reg Guide under power 17 losses. And now we have an external hazard, volcano, 18 and environment and site.
19 Did they get lost there? Or, I mean, you 20 could flip the question, why are earthquake, and 21 flooding, and power losses are not in siting?
22 Those decision-based go a little different 23 here because much of the basis for discussion is 24 because it's CFPP and TerraPower factors. Why here?
25 MR. BENNER: I'm going to defer to Jenise.
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87 1 MS. THOMPSON: Yeah. I was going to say, 2 I can chime in with a little bit of a history on that.
3 And then I don't know if Ed O'Donnell is on the call 4 or in the room, but he may have some -- he's the 5 project manager from Research, the Reg Guide project 6 manager for Reg Guide 4.26.
7 But initially the Reg Guide didn't start 8 off in Section 1 of the Reg Guides or in 1, I don't 9 know what it's called exactly. And it was moved to 10 Section 4 for Category 4 because at the time we were 11 still discussing the applicability of the Reg Guide 12 and whether this was something that could be expanded 13 to include non-power reactor facilities.
14 So, it was moved into siting instead. So, 15 that if at some point in the future the scope or 16 applicability of the Reg Guide were to expand, that we 17 would already be in that siting space rather than in 18 a reactor space only.
19 But I don't know if Ed has more to add on 20 that.
21 MR. O'DONNELL: No. No, well said. Well 22 said, Jenise.
23 MEMBER KIRCHNER: Go ahead.
24 MR. O'DONNELL: No further comment.
25 Jenise expressed it very, very well.
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88 1 MEMBER KIRCHNER: Yeah.
2 And I was just saying to Bob, the other 3 thought in the public meeting back in 2021 was 4 although it had power reactors in the titles, it could 5 apply equally well to a radiological production 6 facility.
7 MEMBER MARTIN: -- and come to the same 8 conclusion that those belong in 4?
9 Is it just, like, scattering around not 10 the best way to design, you know, the framework issue?
11 Not a safety issue, seems like it's lost in this 12 situation.
13 CHAIRMAN REMPE: Sounds like another 14 reason to think about another website.
15 MEMBER KIRCHNER: Yes, Dennis, go ahead.
16 DR. BLEY: Yeah. On this same line, I 17 understand and appreciate where you've moved it. I 18 don't understand why you keep nuclear power reactor 19 sites in the title, you know, instead of something 20 like nuclear facilities which seems is equally 21 appropriate for either of them.
22 MS. THOMPSON: That's a good point. And 23 I think it's about the point for us to consider in the 24 future in another revision to the Reg Guide. Because 25 I agree with you, I do think this would be applicable 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
89 1 to other nuclear facilities that would need to 2 consider volcanic hazards in their license 3 applications.
4 So, that's something we can take back and 5 when we're looking to revise the guide in the future 6 we can take a very hard, close look at the 7 applicability section and see if we can change the 8 title and alter the applicability to more widely cover 9 all of the NRC licensed facilities.
10 CHAIRMAN REMPE: This is Joy. Then I have 11 a question.
12 I've heard some really simple suggestions.
13 And this is, this could be an information briefing.
14 But the committee can always decide to write a letter 15 at any time. That's a risk that you're well aware of.
16 Walt's shaking his head again.
17 A simple one-page memo saying, hey, we 18 were briefed on this, and during the meeting we 19 proffered a couple of suggestions. I don't know if 20 it's worth it or not, but it's something I'd bring up, 21 but.
22 MEMBER KIRCHNER: In my opinion I would 23 not recommend writing a letter now. Let's see it put 24 to the test. We have applications coming in. We 25 could -- I don't think we have any major comments to 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 1 offer that weren't offered in our letter back in April 2 of 2021.
3 For example, this very last topic of the 4 title was suggested that I don't think that rises to 5 the level of writing a letter that the title should 6 say nuclear facilities.
7 CHAIRMAN REMPE: No, I'm thinking more 8 about the global approach for applicants, another 9 change to a website like what happened if Charlie does 10 a license step.
11 But, anyway, that's just something to 12 think about. And I'm not looking or pushing for 13 another letter. But I hope the thoughts don't get 14 lost because they're just individual comments now, 15 they're not a committee position.
16 Anyway.
17 MEMBER KIRCHNER: Members, further 18 comments?
19 With that, I want to thank both Jenise and 20 Eric. Thank you for your informative presentation.
21 I'd just make one comment. I can't let 22 this one go.
23 Jenise, I think I heard you say something 24 to one of the questions that in your gut -- and maybe 25 I misheard you, I'll go back and look at the record --
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91 1 but to what extent, maybe lead with this, to what 2 extent when you screen in using 4.26 would you prefer 3 the applicant do with the volcanic hazards, 4 particularly those that could be kept on the ash side, 5 because that can be fairly widespread, but if you 6 screen in, to what extent -- and I was the one who 7 made the comment about macro decisions, look for the 8 high ground, for example, to avoid lava flows, and 9 avoid flooding as a result of lava flows, et cetera --
10 to what extent should the guidance in 4.26 suggest to 11 the applicant don't necessarily try and calculate your 12 way out of the problem given the large uncertainties 13 but take the high ground -- pardon my metaphor -- at 14 what point do you practically, you know, are you 15 looking for the applicant to, as I said, take the high 16 ground to avoid extensive calculations along the lines 17 of Vesna's questioning, how do you risk inform 18 something that has huge uncertainty?
19 Maybe I'll just leave that as a thought 20 for the future because one would, in my gut reaction 21 to this, is one would hope that the applicants aren't, 22 you know, parking a site on a vent and then trying to 23 calculate their way out of the problem.
24 Is that a rational expectation?
25 MR. BENNER: I'll add a generic -- this is 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
92 1 Eric Benner -- I'll add a generic piece and then 2 Jenise can go deeper.
3 We actually just had a knowledge 4 management session with the staff and NRR on the topic 5 of clarity versus consulting. And because there, you 6 know, we're cautioned to not consult. So, regarding 7 sort of, you know, directing an applicant to both 8 physically and metaphorically take the high ground, we 9 wouldn't do that.
10 But what we could do and should do is if 11 they are, you know, going down a path that's going to 12 rely on calculational, you know, for methodology, and 13 particularly if they are picking a site that is on the 14 low ground, we can point out the challenges of that 15 approach.
16 And should point out how much of a risk 17 it's going to be for them to get an acceptable 18 regulatory finding.
19 So, that's sort of the generic case. And 20 I'll turn it over to Jenise for, again, specifics on 21 these hazards.
22 MS. THOMPSON: Yeah. And I appreciate 23 Eric's point. Because it really isn't our place to 24 redirect them to change their site. We don't have 25 essentially what amounts to a site exclusion criteria.
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93 1 And if you recall back in I think the 2 February 2020 presentation, maybe April of 2021 as 3 well, that's one of the reasons we did not endorse the 4 IAEA safety guide on volcanic hazards because they, 5 they do have site exclusion criteria for volcanic 6 hazards that if that hazard would impact the site, 7 that site should not be considered for construction.
8 And that doesn't -- that's not consistent 9 with the NRC's risk-informed approach to regulation.
10 So, I think there, as Eric said, there 11 would be the opportunity for a lot of early 12 discussions on how those initial siting decisions were 13 being made, and also looking to all of -- and if 14 numerical modeling is being relied upon to demonstrate 15 the safety of the site, then looking very, very 16 closely at that safety case being made by the 17 applicant is in their specific application.
18 But, again, taking that, that approach 19 where it's not our position to direct the prospective 20 applicant one way or another but to provide clarity on 21 the regulatory requirements and the regulatory basis 22 and justification that should be provided in their 23 application. And that would be, I think, a lot of 24 early discuss -- early and often discussions in that 25 pre-application.
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94 1 MEMBER KIRCHNER: Thank you, Jenise.
2 Jenise, thank you.
3 Stephen.
4 DR. SCHULTZ: Walt, this is Steve Schultz.
5 MEMBER KIRCHNER: Yes.
6 DR. SCHULTZ: Jenise, a follow-up question 7 there.
8 That is, as you do the reviews of 9 TerraPower and the NuScale, I mentioned NuScale as 10 part of the facility process because that's the design 11 I want to get to that, you know, for the design side 12 you're going to get a lot of information about the 13 capabilities that the designers believe they have with 14 regards to the hazards that you've gone through today.
15 You know, when a designer puts forward 16 their seismic design, they have a particular 17 deterministic valuation of what the design capability 18 of the facility is for seismic hazard. And the same 19 will come out with regard to the design capability for 20 the ash, for the capabilities associated with 21 flooding, and so forth.
22 And so, there's, as you mentioned earlier, 23 there's certain design aspects that will be available 24 for decision making associated with the overall 25 evaluation. There's that side of it, too.
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95 1 MS. THOMPSON: Yes. And that's something 2 that we're planning to support the reviews of these 3 volcanic hazards assessments, recognizing that I, I'm 4 a geologist and the characterization of the hazard is 5 my wheelhouse. And once we get into looking at the 6 effects of those hazards on these structures, the 7 different components for that specific design, that's 8 when we will be passing the baton, if you will, on to 9 the various systems engineers for the potentially-10 impacted systems, and relying on their expertise in 11 support of that licensing review.
12 So, this is where we're, we're 13 anticipating additional overlap in review areas where 14 volcanic hazards may now be passing over not just to 15 structural or geotechnical engineering, but also 16 looking at nuclear systems engineering and passing 17 that information on to them to do the PRA review. So, 18 it's going to be a much wider scope of review, not 19 just looking at the hazard, but where those pass-off 20 points are between the hazard staff and the 21 engineering analysis staff.
22 So, that that's a review that's going to 23 follow the normal course of review for the nuclear 24 systems engineers as their, part of their safety 25 review. And we're just providing an input to that 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 1 review for them.
2 DR. SCHULTZ: Yes. And --
3 MS. THOMPSON: So, lots of, lots of review 4 interfaces here to be mindful of as we move forward, 5 not just the geologic hazard components.
6 DR. SCHULTZ: That's good.
7 And on that side, there's a lot of 8 features and evaluations that will be done. And they 9 can be done on a one time basis. They can be used for 10 other evaluations and don't need to be repeated by 11 every applicant or every designer. It can be 12 established what their design capabilities are.
13 MS. THOMPSON: Yeah. And that's part of 14 why we're really focused, even though we haven't 15 completed the review yet, why we're focused on 16 documenting those lessons learned to inform any future 17 revisions to Reg Guide 4.26 so that we're capturing 18 those, those interfaces and those conclusions that 19 have already been made.
20 I know we started off with a question 21 about the capability of SSEs to withstand various 22 volcanic hazard loads. So, this is going to give us 23 the firsthand experience and knowledge to start 24 documenting that and using that learned experienced in 25 future license reviews as well.
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97 1 DR. SCHULTZ: Excellent. Thank you.
2 MEMBER KIRCHNER: Okay. With that, thank 3 you to everyone. Thank you again to Jenise Thompson 4 and Eric for being here with us today.
5 And I yield back a couple minutes of our 6 time.
7 CHAIRMAN REMPE: Thank you very much.
8 Okay. At this point I want to go off the 9 record, okay, Jim. And we'd like to request that you, 10 along with Eric, return at 1:00 p.m. this afternoon.
11 (Whereupon, the above-entitled matter went 12 off the record at 10:27 a.m. and resumed at 1:00 p.m.)
13 CHAIRMAN REMPE: Okay, it's 1:00 p.m. on 14 the East Coast, and we're back in session. And at 15 this time I'd first like (audio interference) to ask 16 -- hold on.
17 And now I'd like to ask Member Brown to 18 lead us through our first topic for today.
19 MEMBER BROWN: Okay. Just, I'm going to 20 make some kind of a game plan, opening comments, since 21 we're kind of out of sorts on the way we normally do 22 stuff.
23 Because of the Commission's desire to get 24 something out within a year of the SRM, the normal 25 process of scheduling a Subcommittee, and then another 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 1 meeting with several of us, kind of out of sorts. So 2 we requested to combine it with this full Committee 3 meeting so that we can get ahead of the ball game.
4 And hopefully help you meet your goals. And it also 5 will allow you to at least hear our comments in the 6 transcript on the (audio interference) BTP.
7 I intend to try to get through this, the 8 slides, in an expeditious manner. But you know how it 9 works with the Committee people, they undoubtedly have 10 questions. I will probably save mine until later, but 11 at the end. And then Tom and I probably both will 12 give some additional ones if we don't cover them all.
13 But my object here is to get all of our, the two 14 people who probably did the most review on it, give 15 our comments and thoughts and more inconsistencies in 16 the transcript so you would have them.
17 And the objective of all of this is to try 18 to get a letter which documents those. Hopefully we 19 can do it this Committee meeting, if the Committee 20 agrees. But I'm just proposing it. There will be the 21 comments and stuff in it. If not, we would get it out 22 in the October meeting. That will still get it, but 23 you would already have the comments.
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99 1 of public comments on the 19th. You can obviously do 2 it if you want to, if we don't get to the letter until 3 October. But they can be done in conjunction with the 4 public comments. If the Committee agrees with me at 5 the end of this whole shooting match.
6 So that's kind of, did I miss anything, 7 Joy, or did I kind of get it, that's still in line 8 with your game plan, right?
9 CHAIRMAN REMPE: Sounds good. I hope --
10 MEMBER BROWN: Okay.
11 CHAIRMAN REMPE: Court reporter, could you 12 get --
13 MEMBER BROWN: Can you hear me? Can you 14 hear me, court reporter? Uh-huh.
15 (Off-microphone comments.)
16 MEMBER BROWN: All right.
17 CHAIRMAN REMPE: But is it enough to put 18 on the transcript --
19 MEMBER BROWN: Were you able to get me on 20 the transcripts?
21 (Off-microphone comments.)
22 MEMBER BROWN: Okay. Well, I'm 23 fundamentally done. I was going to pass off to -- oh, 24 one other thing. For the Committee's purposes I had 25 Christiana, since the old SRM was93-087 that had all 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
100 1 the points that's been, and we had a BTP, we had a 2 subcommittee meeting, a full Committee when we did Rev 3 8, that's based on the old SRM.
4 Gave you a copy of the, and there are all, 5 the changes that the Commission made on the original 6 SRM are in red so you can see what was done back in 7 '93. What the Committee Commission did on the 222-8 0076 is also, what the Commission changed, also is in 9 red. You've got a copy so you can see what the 10 differences are as they progress through the 11 discussion to make sure everything is there.
12 Mine understanding of the Staff's object 13 was to leave all the stuff relative to diverse best 14 estimate systems the same. Only do what was necessary 15 to get the risk-informed guidance direction that the 16 Commission did. And they will address that, and how 17 they did that, and didn't mess up anything else. And 18 that's where, maybe, where some of the comments come 19 in.
20 So with that, go ahead.
21 CHAIRMAN REMPE: Just one clarification, 22 just because this is a public meeting, I think it's 23 great that you and Tom have got your comments 24 together, but, and, you know, it's great that you're 25 going to put it on the record and the Staff can see 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 1 it, but of course, we all know that there are two 2 individual --
3 MEMBER BROWN: Yes.
4 CHAIRMAN REMPE: -- respondents in the 5 letter --
6 MEMBER BROWN: No, absolutely. Those are 7 --
8 CHAIRMAN REMPE: So, just wanted to make 9 sure. I know that the Staff knows, I know --
10 MEMBER BROWN: Yes, I apologize for that.
11 (Simultaneously speaking.)
12 MEMBER BROWN: I should have, I know you 13 know that's clear, but nothing is ever official until 14 the Full Committee puts it Betty Crocker Housekeeping 15 seal of approval on it.
16 (Laughter.)
17 MEMBER BROWN: With that, I will turn it 18 over to Eric for some opening comments.
19 MR. BENNER: Thank you, Chair Rempe, 20 Member Brown. My name is Eric Benner, I'm the 21 Director of the Division of Engineering and External 22 Hazards. And the I&C technical review is conducted 23 within my division.
24 We both very much appreciate the 25 Committee's flexibility on this issue, as because 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 1 Member Brown said, once we got, we had made the 2 proposal for our risk-informed alternative for 3 diversity and the Commission paper, the reference 4 number that Member Brown gave, SECY-222-0076, when the 5 Commission gave us their direction back, which 6 essentially approved the Staff's proposal with some 7 changes, they gave us a year to promulgate it in 8 implementing guidance.
9 So that significantly challenged the 10 Staff, setup a schedule to achieve the Commission's 11 direction. And so again, we appreciate the 12 Committee's flexibility in working with us on the 13 scheduling.
14 We also very much appreciate getting the 15 Committee's feedback as soon as possible. So we do 16 understand that it would come in the form officially 17 of a letter. That being said, we'll be listening to 18 any input we hear, and will be looking at ways to 19 either incorporate it for the version that goes out 20 for the public comment or as part of our comment, 21 public comment period, and issue resolutions.
22 So I do applaud you taking the time to 23 give us the feedback now, because I think were we to 24 go through the public comment period and then get 25 significant feedback from the Committee after that, 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 1 that could likely result in another public comment 2 period, so we would not be able to achieve the 3 schedule the Commission had given us. So this at 4 least gives us an opportunity to meet that schedule, 5 so we appreciate that opportunity.
6 We have three main presenters, which I'll 7 introduce. Samir Darbali and Norbert Carte are both 8 I&C reviewers within my division.
9 Steven Alferink is a risk and reliability 10 analyst. And he is in our office, the Office of the 11 NRR's Commission of Risk Assessment. And this is 12 testament of that, that the I&C Staff and the Risk 13 Staff did work closely, both in developing the 14 proposal to the Commission and in the implementing 15 guidance.
16 So with that, I'll turn it over to Samir 17 Darbali.
18 MEMBER BROWN: One more observation is 19 that when you get to, the further comments are 20 extensive and/or make very, your dramatic type changes 21 that you all did, that we would, not a necessity, 22 needing another meeting afterwards. That wouldn't be 23 driven by us, it's largely driven by what the public 24 come through and what you all have to deal with it.
25 MR. DARBALI: Yes.
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104 1 MEMBER BROWN: So just wanted to make sure 2 that was, you understood that is the final thing on 3 the table if necessary.
4 MR. DARBALI: Okay.
5 MEMBER BROWN: Not intending to do that.
6 Gives you a way with it a little.
7 MR. DARBALI: All right. So thank you and 8 good afternoon. So today we'll provide some 9 background information by going through the original 10 four points, as Charlie mentioned.
11 MEMBER BROWN: And can we, want to check 12 to see if the court reporter can hear you?
13 MR. DARBALI: Can you hear me?
14 CHAIRMAN REMPE: Court reporter, can you 15 hear Samir?
16 (Off-microphone comments.)
17 MR. DARBALI: Okay, thank you. All right, 18 so --
19 MEMBER BROWN: He asked you to speak 20 louder.
21 MR. DARBALI: Yes.
22 MEMBER BROWN: You should be able to do a 23 high resonant voice.
24 MR. DARBALI: Okay. So we're going to be 25 going through the original four points from SRM-SECY-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 1 93-087 and the new points in SRM-SECY-222-0076. We'll 2 then talk about the Commission direction from the SRM 3 and the Staff's proposed response before we go into 4 detail with substantive changes to BTP 7-19. Well 5 finish with the next steps for revising the BTP.
6 Now we'll go through the next slide for 7 Point 1 of SRM-SECY-93-087. So Point 1 requires a D3 8 assessment to demonstrate that common cause failures 9 have adequately been addressed. The language in this 10 original first point places the focus on the D3 11 assessment of the proposed I&C system rather than on 12 the facility install in the proposed system.
13 This point also uses the term, common mode 14 failures, instead of common cause failures. And these 15 were things that we were looking to clarify in the 16 revised point, which we'll look at later.
17 Next slide please. So Point 2 requires 18 that the D3 assessment analyze each postulated CCF for 19 each event evaluated in the accident analysis using 20 best estimate methods to demonstrate adequate 21 diversity. As you see in red, the addition that the 22 Commission made to this point back in 1993 for the use 23 of best estimate method.
24 Next slide. Point 3 requires a diverse 25 means of accusation if a CCF could disable a safety 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
106 1 function. And the Commission added that the diverse 2 function can be performed by a system that is not 3 safety related.
4 Next slide. For Point 4 it requires 5 diverse maintenance for a room display and manual 6 controls for actuation of critical safety functions.
7 The Commission edited this point to allow for the 8 diverse display of the manual controls to be performed 9 by equipment that is not safety related.
10 And now we'll go to the four points in 11 SRM-SECY-222-0076, which can be found in the enclosure 12 to the SRM. So for Point 1 the first paragraph is 13 similar to that of the original point. But we've 14 clarified that the focus of the D3 assessment is the 15 facility in following the proposed system. And we 16 also replaced the term, common mode failure, with 17 common cause failure.
18 MEMBER KIRCHNER: Could you tell us, in 19 your own words, why shall has been changed to do not.
20 MR. DARBALI: The Commission made that 21 change, but did not provide a specific reason why.
22 MR. BENNER: We interpret it to mean the 23 same.
24 MEMBER KIRCHNER: Okay. So, effectively 25 -- because most of your regulatory language is shall 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
107 1 --
2 (Simultaneous speaking.)
3 MEMBER BROWN: Shall is more legalistic, 4 and must is must. Shall is legalistic language, and 5 the must fundamentally means figure it out for 6 yourself. They have choices. It flows in the, a bit 7 of what I would call, I don't want to call it a risk, 8 but engineering judgment thought process is how you 9 proceed. That's my thoughts on it.
10 MEMBER KIRCHNER: Thank you, Samir.
11 MEMBER BROWN: Must is not legalistic.
12 MR. DARBALI: Now, thank you for the 13 question. So for Point 1 we also added a new sentence 14 to explain that a D3 assessment must be commensurate 15 with the risk-significant of the proposed I&C D3.
16 Next slide for Point 2. Thank you. So 17 the original Point 2 only covered best estimate 18 methods. And we're keeping that here. The new Point 19 2 covers best estimate methods and risk-informed 20 approaches.
21 For the new Point 2, a new first paragraph 22 was added to explain that the D3 assessment must be 23 performed with either best estimate assessments, a 24 risk-informed approach or both. The second paragraph 25 is essentially the same as that of the original Point 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 1 2, referring to what is required when using best 2 estimate method.
3 Next slide. Thank you. So this is the 4 third paragraph of the revised Point 2. And it was 5 added for the use of a risk-informed approach. And 6 explains that the Staff will review applications for 7 consistency would establish NRC practices and guidance 8 for risk-informed decision making.
9 For example, Regulatory Guide 1.174 and 10 reg, for operating light water reactors. And 11 Regulatory Guide 1.233 for non-light water reactors.
12 Next slide.
13 MEMBER ROBERTS: This is Tom Roberts.
14 MR. DARBALI: Yes.
15 MEMBER ROBERTS: The Commission added the 16 Reg Guide 1.233, if I understand your markup.
17 MR. DARBALI: Yes.
18 MEMBER ROBERTS: That was the only 19 reference I could find in the revised BTP to that Reg 20 Guide. Do you know why the Commission added that or 21 do you think there is a need to provide guidance to 22 the applicants or the licenses of how they apply Reg 23 Guide 1.123 to this scenario?
24 MR. DARBALI: So the intention, when we 25 wrote the SECY-22-0076 we intended it to cover all 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 1 reactor types. And so, I believe the Commission's 2 intent, so we provided an example of 1.174. I believe 3 the Commission's intent with 1.233 was to also show an 4 example guidance for non-light water reactors.
5 MEMBER ROBERTS: Right. But the BTP 6 doesn't further expand on that?
7 MR. DARBALI: Correct. So the BTP, Branch 8 Technical Position 7-19, is part of a vendor review 9 plan for operating in light water reactors. And so, 10 the guidance for non-light water reactors really 11 wouldn't fit within BTP 7-19. So the guidance in BTP 12 7-19, again, covers light water reactors, guidance for 13 non-light water reactors is founded elsewhere.
14 MEMBER BROWN: I'll amplify that because 15 that was one of my observations was that the 16 regulatory guidance list that you all list does not 17 even list 1.233, yet it is referenced in the SRM. And 18 this really applies to both light water and non-light 19 water based on the general language. So it just 20 seems, to us, that if it's in the SRM and the 21 Commission edited it, it seems like it ought to be in 22 addition to just the Point 3 or Point 2 phraseology, 23 it really ought to be in the list of identified 24 regulatory, I forgot what section it is. It's right 25 up in the front --
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110 1 MEMBER ROBERTS: Yes.
2 MEMBER BROWN: -- where all the regulatory 3 guidance is sitting. That was just an observation 4 that we would be making. I think Tom is --
5 MEMBER ROBERTS: Sure. And perhaps the 6 BTP should explain why it's not further described.
7 Okay.
8 MEMBER BROWN: Yes. That would be an 9 alternative approach.
10 MEMBER ROBERTS: Which would then lead to 11 wonder, okay, what document applies for new advance 12 non-light water reactors when they're figuring out how 13 to apply the (audio interference)? Tom, what's your 14 answer that question?
15 (Off-microphone comments.)
16 CHAIRMAN REMPE: Okay, so let's try and 17 not move the microphone anymore. And use your command 18 voice, Charlie, I know you've got it.
19 (Laughter.)
20 MEMBER BROWN: I will do that.
21 CHAIRMAN REMPE: Okay.
22 MEMBER BROWN: It's present most of the 23 time.
24 MEMBER ROBERTS: So I'll repeat the 25 question. If BTP 7-19 is not applicable to advance 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
111 1 the non-light water reactor, what --
2 MR. DARBALI: So --
3 MEMBER ROBERTS: -- is?
4 MR. DARBALI: So the design review guide, 5 or DRG, provides the I&C review guidance for advance 6 non-light water reactors. And that would be the 7 document, that document goes together with Reg Guide 8 1.233. That document is performance based and risk-9 informed (audio interference) inception. But again, 10 that's a separate document, separate activity from 11 BTP.
12 MEMBER ROBERTS: Okay. So is your intent 13 to revise that document consistent with the BTP 14 revision?
15 MR. DARBALI: So currently the folks in 16 the division of advance reactors, DANU, in NRR are 17 looking at what updates are needed, if any, to meet 18 the SRM.
19 MEMBER ROBERTS: Okay, thank you.
20 MEMBER BIER: If I can follow-up with a 21 related question.
22 (Off-microphone comments.)
23 MEMBER BIER: That's all right, I'll come 24 around. Thank you.
25 If I can follow-up with a related 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
112 1 question. From the existing document it looks like 2 the definitions of what counts as risk-significant are 3 geared to traditional LWR criteria like, I forget 4 exactly what the numbers are, but there was a number 5 for core melt and another number for LERF as 6 frequencies, but those may not apply to some reactor 7 designs. Like if there is no solid core or whatever, 8 and has there been thought about how the definition of 9 risk-significant would apply to other designs?
10 MR. DARBALI: I'm going to turn it over to 11 Steven Alferink.
12 MR. ALFERINK: So the answer is, yes, 13 we're certainly thinking about it. But specifically 14 because the BTP 7-19 is for light water reactors.
15 That is why we kept (audio interference).
16 CHAIRMAN REMPE: So now I'm getting 17 confused. I thought you were expanding it to non-18 LWRs, right?
19 MR. DARBALI: No. The BTP is still for 20 light water reactors.
21 CHAIRMAN REMPE: Only?
22 MR. DARBALI: Only. Yes.
23 CHAIRMAN REMPE: But it could go to the 24 advance light water reactors, like the small modular 25 light water reactors for example?
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113 1 MR. DARBALI: Correct. Yes.
2 CHAIRMAN REMPE: Okay. So then the 3 question would be still relevant, and I'd elaborate 4 that there is, the definition of the CCF is not risk-5 significant if the following criteria are met for the 6 sensitivity analysis, and the increase in CCF or the 7 increase in LERF is less than in both of those cases.
8 And I would think that, we wrote a letter 9 years ago about, eventually you're going to get to say 10 that these criteria, you know, it's really easy to 11 meet those, and it could be significant really is 12 where I was going with it too because I had the same 13 thought for it.
14 MR. DARBALI: So I believe we do have some 15 slides when we get to the discussion of risk-16 significance. So we could explain in some detail --
17 CHAIRMAN REMPE: Sure.
18 MR. DARBALI: -- later. Okay. So we 19 could go to the next slide.
20 MEMBER BROWN: I just can't help myself.
21 And I probably lost -- this is light water versus non-22 light.
23 Why isn't the BTP applicable in non-light 24 water reactors? I mean, you got systems and 25 protection systems, why don't those same defense-in-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
114 1 depth issues apply to non-light water reactors? Or 2 are they just so safe that nobody has to worry about 3 them?
4 MEMBER BROWN: No, it's not, it's not 5 really a technical issue regarding the applicability, 6 it's that fact that the BTP is part of the standard 7 review plan for light water reactors.
8 MEMBER BROWN: But why does that make any 9 difference? I mean, if BTP is a NRC document it 10 should be able to be used. Can you hear me?
11 (Off-microphone comments.)
12 MR. DARBALI: Dinesh Taneja, would you 13 like me to provide some additional insights?
14 MR. TANEJA: Yes. This is Dinesh Taneja.
15 So, Member Brown, to answer your question, standard 16 review plan is one of the NUREG-0800. And when you 17 look at the NUREG-0800 it specifically states in our 18 regulation that that guidance applies to light water 19 reactors, okay?
20 So when we developed the DRG, and Reg 21 Guide 1.233, it was named different for that very 22 reason that we wanted to distinguish it from the SRP.
23 Okay? When we presented our DRG to the Committee 24 here, I think we came to an agreement that the 25 guidance can be used for light water reactors, but it 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
115 1 was intended to be developed for non-light water 2 reactors.
3 Now that guidance, you know, I believe is 4 already in conformance, or at least the intent of the 5 SRM already. So we are looking at, to see if we can 6 modify our revisement, but the intent is already being 7 met because it's already risk-informed and performance 8 based.
9 So that's guidance is what's going to 10 serve the Staff very well in looking at all these non-11 light water designs in combination with the Reg Guide 12 1.233.
13 MEMBER BROWN: But as I reviewed that it 14 was also a spinoff of the original efforts on the 15 design specific review guidance that we built for --
16 MR. TANEJA: That is true.
17 MEMBER BROWN: -- one of the early light 18 water reactors, okay, that was being proposed by B&W, 19 I believe, at the time.
20 MR. TANEJA: Correct.
21 MEMBER BROWN: And then we applied it to 22 the NuScale and others. So I'm just saying, these 23 things are so vanilla --
24 MR. TANEJA: They are. I agree with you.
25 MEMBER BROWN: For some reason that just 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
116 1 doesn't make sense to divorce 7-19 which has got a 2 plethora of information on what to do on overall 3 defense-in-depth type perspective. And I suspect it's 4 not all duplicated in the DRG, okay, relative to 5 what's, I mean, this is 38 or 39, 40 pages worth of 6 stuff. This is pretty detailed.
7 MR. TANEJA: Correct.
8 MEMBER BROWN: So anyway, it's an open, 9 it's just a question. We --
10 MR. TANEJA: Yes, it is. And the other 11 point is that, you know, Staff really has all these 12 tools available. So it doesn't limit us to not use 13 these tools when we are reviewing an application 14 regardless of whether it's for advance non-light water 15 reactor or an SMR or a design mod. So these are the 16 set of tools that we do have available. We have to 17 just, you know, legally distinguish them in certain 18 buckets.
19 MEMBER BROWN: Yes, again, after you all 20 do your review, applicants need to know what you're 21 reviewing too. And if you're going to invest using it 22 in a way that "this perception is not," then it kind 23 of surprises the applicants as to, oh, you're making 24 comments that are relative to guidance that's just not 25 in the other, the non-light water side.
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117 1 MR. TANEJA: Yes.
2 MEMBER BROWN: We're just trying to make 3 the point that this doesn't seem to connect the dots 4 very well. And it might be useful in this document 5 now to at least provide a little more of expansive 6 consideration of its application because it's very 7 generic.
8 MR. TANEJA: Yes.
9 MEMBER BROWN: It doesn't matter. You can 10 make this thing out of chewing gum, reactors out of 11 chewing gum, and it would still apply. That's 12 sarcasm, but then there is something. Okay?
13 MR. TANEJA: Understood.
14 MEMBER BROWN: Okay. Ought to have some 15 humor in there.
16 (Laughter.)
17 MEMBER BROWN: All right, Committee, can 18 we, Tom, are you finished?
19 MEMBER ROBERTS: Yes.
20 MEMBER BROWN: Okay.
21 MR. DARBALI: Okay, thank you. Next 22 slide. So the original Point 3 only discussed the 23 need for a diverse means with a CSF, critical safety 24 function. The new Point 3 now also covers designed 25 technics and mitigation measures, other than 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
118 1 diversity. And the first paragraph was added to 2 explain that if technics or measures, other than 3 diversity, are credited in the assessment, that they 4 must be adequately justified commensurate with the 5 risk significance of the CCF.
6 Next slide. The second paragraph of the 7 new Point 3 is essentially the same as the original 8 Point 3 as it explains that, what is required when a 9 diverse means is credited in the assessment. Fr 10 example, the diverse means could be manual or 11 automatic or performed by a system that is not safety 12 related.
13 Next slide. And this third paragraph in 14 the new Point 3 was added to explain that if design 15 technics or measures, other than diversity, are not 16 demonstrated to be adequate with a risk-significant 17 CCF, than a diverse means is required.
18 Next slide. For Point 4, the language in 19 SECY-22-0076 was essentially the same as the original 20 Point 4. The Commission in the SRM added the words 21 "risk-informed" to clarify that the identification of 22 critical safety functions could be performed using 23 risk information. The Commission also added that last 24 sentence to allow applicants to propose a different 25 approach if the plants design passes the commensurate 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
119 1 level of safety.
2 CHAIRMAN REMPE: I have a question.
3 MR. DARBALI: Yes.
4 CHAIRMAN REMPE: In our recent reviews of 5 some of the advance non-LWRs, and we issued that when, 6 and how they, while they define their critical safety 7 functions has come up. For example, Part 53 Framework 8 A has a certain way of doing it. It's a little bit 9 more fussy with Framework B, which now go, are 10 combined or whatever.
11 But in the regulations the critical safety 12 functions appears differently in the guidance in the 13 current NRC regulations. Does the operating fleet 14 have some document that says, okay, for this plant our 15 critical safety functions are?
16 Are they going to have to submit 17 something?
18 How does that work, do you know what their 19 critical safety functions are when they come in?
20 MR. DARBALI: So the original SECY-93-087 21 provided an example of critical safety functions. And 22 those could be, those examples could be tied back to, 23 I believe IEEE 497 and then ANS standard from 1980, I 24 believe ANSI-ANS 4.5.
25 Those really, after Three Mile Island, 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
120 1 where the documents that identified, for post-accident 2 monitoring, what those critical safety functions are.
3 But again, those are examples for light water 4 reactors. There is no regulation to say those are 5 specifically the only critical safety functions.
6 And so, when an application comes in, they 7 identify the controls and display to meet the critical 8 safety functions. But for a typical digital I&C 9 upgrade licensing review, we're not evaluating the 10 licensees determination of what those critical safety 11 functions are. So they provide those functions and 12 the controls and displays for those functions.
13 CHAIRMAN REMPE: You think with an LWR 14 there wouldn't be variability.
15 MR. DARBALI: Correct.
16 CHAIRMAN REMPE: But if someone were to 17 try and use this for an advanced small modular light 18 water reactor, or a non-LWR, you know, it would be 19 very important to have agreement with the staff what 20 those critical safety functions are, is why I'm kind 21 of bringing this up.
22 MR. DARBALI: Right. And we do have, we 23 did clarify the section of the BTP that talked about 24 critical safety functions. We do have a slide on 25 that. And so to explain, at a very high level, what 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
121 1 the importance of those critical safety functions are.
2 And based on that licensing can make their 3 determination. But we have a slide on that.
4 CHAIRMAN REMPE: Yeah, I didn't see 5 chemical, control chemicals (coughing) and things like 6 that.
7 MR. DARBALI: Right. Right.
8 CHAIRMAN REMPE: So that's why I'm kind of 9 thinking that it may be something --
10 MR. DARBALI: Yes 11 CHAIRMAN REMPE: -- that may come up.
12 Anyway, go ahead.
13 MR. DARBALI: Okay, thank you.
14 MEMBER DIMITRIJEVIC: And I have a like 15 comment. The column, the risk-informed critical 16 safety function, that's not the thing, so, I mean, 17 it's a critical safety function which are selected 18 using risk-informed principles. But there is not such 19 a thing as risk-informed critical safety functions.
20 MR. DARBALI: We agree.
21 (Laughter.)
22 MR. DARBALI: No, we agree with that 23 statement. Okay.
24 So, as we just saw, the Commission 25 approved, with some edit, the Staff's recommendation 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
122 1 to expand the policy to allow the use of risk-informed 2 approaches to demonstrate the appropriate level of 3 defense-in-depth. The Commission also provided 4 direction to the Staff to clarify, in the implementing 5 guidance, that the new policy is independent of the 6 licensing pathway and to complete the final 7 implementing guidance within a year, which is May 24th 8 of next year.
9 MEMBER BROWN: I take it that means, I'm 10 speaking loud enough, that means Part 53 applies, as 11 well as the licensing pathways, even though it's not 12 official yet?
13 MR. DARBALI: So if, right. When we talk 14 about --
15 MEMBER BROWN: It's intent.
16 MR. DARBALI: The intent, right.
17 MEMBER BROWN: Yes.
18 MR. DARBALI: But without having a final 19 Part 53 we can't --
20 MEMBER BROWN: I got that --
21 MR. DARBALI: -- really --
22 MEMBER BROWN: -- I just wanted to make 23 sure that we had the same --
24 MR. DARBALI: Right. Right.
25 MEMBER ROBERTS: And not to beat a dead 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
123 1 horse, but you had raised a point earlier that BTP 7-2 19 is not a complete response to the Commission 3 direction, and so I assume you got other parts of this 4 process also laid out, like design review guide, if 5 that's the appropriate document to change?
6 Because you come here with just the BTP, 7 so I'm wondering if there is a public interface plan 8 and a schedule to go through all the other documents 9 that are required in a year?
10 MR. DARBALI: Dinesh, could you provide 11 some insights on the DRG?
12 MR. TANEJA: Right. So we looked at the 13 Reg Guide 1.233 and we looked at the DRG. The intent 14 of the SRM is already being met by those two set of 15 documents.
16 So the Reg Guide provides the guidance to 17 the applicant, and the DRG is the Staff review guide.
18 Now, if you look at the framework of performing the 19 LMP type of a licensing basis determination, the risk-20 informing it and having built into the process. So it 21 really meets the intent of it.
22 So at this time we are just evaluating to 23 see, you know, do we need to just revise it to add the 24 word SRM in it or do we want to take a lesson learned 25 on actual use of those guidance documents and wait 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
124 1 till we get some of the feedback?
2 In the meantime what we intend to do is, 3 with all future applicants and designers we are going 4 to share the SRM information with them and pre-5 application engagements. And we are having workshops 6 on digital I&C review with the DRG.
7 We've had a few workshops already with the 8 industry, and we intend to have some more. So it's 9 one of the topics that we are covering in that one.
10 That's, I think that's the way we are 11 proceeding with addressing the concern of, that this 12 SRM is applicable to all design types regardless of, 13 that's why we are taking care of that very thing. So 14 we will be evaluating, you know, the future revision 15 to those documents.
16 MEMBER ROBERTS: So if we have an 17 applicant who is not using Reg Guide 1.233 or the 18 applicant chose some other approach, they have 19 guidance today, I don't even know?
20 MR. TANEJA: No.
21 (Simultaneously speaking.)
22 MR. TANEJA: They, you know, they will 23 have to propose what they are doing in our pre-24 application engagements. You know, it's like, for 25 example I think we have an SR, you know, BWRX-300 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
125 1 design. That they are coming in with an alternate 2 approach that doesn't meet, you know, the Reg Guide 3 1.233 approach, but they want to use the DRG to view 4 guidance. It doesn't really meet the SRM. But they 5 are using the IAEA framework. So we are dealing with 6 that separate. On a case-by-case basis they're 7 working.
8 MEMBER ROBERTS: Okay. And then on the 9 SMR it exists --
10 MR. TANEJA: Yes. Yes. We are making 11 that available. You know, I mean, we, you know, we're 12 just looking at a topical report from GEH on the SMR, 13 you know, the BWRX-300. And we provided a comment 14 back to them, hey, look at this SECY-22-0076 SRM as 15 well. So it's being communicated to them. Yes.
16 MEMBER ROBERTS: And I'm kind of stuck on 17 the point Charlie made a few minute ago which is, that 18 the DTP is mostly generic.
19 MR. TANEJA: Yes.
20 MEMBER ROBERTS: And it seemed like the 21 non --
22 MR. TANEJA: They could benefit from 23 looking at it too.
24 MEMBER ROBERTS: Right. The non-light 25 water reactor, non-LMP applicant, which seemed to be 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
126 1 very well suited --
2 MR. TANEJA: Right.
3 MEMBER ROBERTS: -- BTP and then, you 4 know, start with this guidance.
5 MR. TANEJA: The licensing framework using 6 the LMP framework, I think it requires you to really 7 model the CCFs early on in the design process, right?
8 MEMBER ROBERTS: Yes.
9 MR. TANEJA: And whereas, when we are 10 looking at these digital upgrades to operating 11 reactors, the part is after the fact part. So it's 12 kind of, you know, how we treat that information. And 13 how the Staff looks at it is kind of different.
14 MEMBER ROBERTS: Yes. Okay.
15 MEMBER BROWN: Let me make a query, can we 16 walk away from this one and get on --
17 MEMBER ROBERTS: Yes.
18 MEMBER BROWN: -- want to make the point 19 that I guess that it doesn't come out, come out, I 20 hope I'm yelling loud enough, that the BTP is generic 21 and should not be, that someone it should be 22 identified as being useable across the type of 23 reactors.
24 Whether you -- to me that would be 25 something we would put up in the preamble or the lead 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
127 1 in or something in the initial DMT to, the general 2 purpose is to provide defense-in-depth, et cetera, and 3 risk-informed information for doing certain things.
4 And the applicants have the ability to evaluate this 5 for their applications without restraints. However 6 you want to phrase that.
7 I don't want to mess with this one 8 anymore, I think we've made the point. Tom, is that 9 okay with you?
10 MEMBER ROBERTS: Sure. I don't want to 11 hijack this meeting, but I'm wondering why it's not in 12 the Reg Guide (audio interference) --
13 (Whereupon, the above-entitled matter went 14 off the record at 1:38 p.m. and resumed at 1:43 p.m.)
15 CHAIRMAN REMPE: Wherever we were, please 16 continue.
17 MR. DARBALI: So on slide 16, we just 18 looked at the information direction. So the staff's 19 proposed response (audio interference) --
20 (Simultaneous speaking.)
21 MR. DARBALI: Can you hear me now? So 22 like I said, the staff's proposed response to meet 23 Commission direction is to revise BTP 7-19. So we are 24 working on Revision 9 which provides guidance for the 25 review of risk informed approaches which may result in 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
128 1 the use of design techniques other than diversity.
2 Because of the one-year metric to issue 3 the final implementing guidance, the staff has focused 4 the edits to the BTP to be mostly toward incorporating 5 the expanded policy. So here are the substantive 6 changes made in Revision 9 of the BTP. For Section 7 B.1.1, this was revised to update the language of the 8 four points.
9 Section B.1.2 was revised to clarify the 10 term, critical safety function. Section B.3.4 was 11 added for the evaluation of a risk informed pre-12 assessment. Section B.3.1.3 was revised to support 13 the evaluation of alternative approaches.
14 Section B.4 was revised to include 15 guidance for the evaluation of approaches (audio 16 interference). We've also added four flow charts to 17 facilitate the use of the BTP. And we also added 18 language from Reg Guide 1.152 regarding communication 19 independence and control of access.
20 And we'll go into the details of all of 21 these changes in the following slides. Next slide, 22 please. So like I said, we updated the language to 23 reflect the points in SR Section 22.76 as well as 24 updated the explanation of the four points. We also 25 added some bullets to help identify the applicable BTP 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
129 1 sections when performing a safety evaluation.
2 CHAIRMAN REMPE: We hear it in the room 3 too. So I think it's better now. Thank you. Go 4 ahead.
5 MR. DARBALI: Next slide. So on Section 6 B.1.2, we clarified that critical safety functions are 7 those most important safety functions to be 8 accomplished or maintained to prevent a direct and 9 immediate threat to the health and safety of the 10 public. So that kind of addresses what's the overall 11 criteria of a critical safety function. We also 12 clarify the critical safety functions that are in SECY 13 93-087, samples representative of operating light-14 water reactors and that other types of reactors may 15 have different critical safety functions based on the 16 reactor design safety analysis.
17 Also that the identification of such 18 critical safety functions may be risk informed.
19 Again, no such thing as risk informed critical safety 20 functions. Risk information can be used based on the 21 side of the facility to determine those critical 22 safety functions. And the intention is that they meet 23 that first rule (audio interference) to the health and 24 safety of the public. And now I will turn it over to 25 Steve Alferink who's going to cover the risk informed 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
130 1 D3 assessment process.
2 MR. ALFERINK: Thank you, sir. Can 3 everyone hear me?
4 MEMBER MARCH-LEUBA: Yeah.
5 MR. ALFERINK: My name is Steven Alferink, 6 and I will discuss the review guidance for risk 7 informed D3 assessment. So this slide illustrates how 8 the staff envisions the risk informed approach getting 9 into the overall D3 assessment process. The D3 10 assessment process starts by identifying each 11 postulated CCF.
12 Once the CCF is identified, it can be 13 addressed deterministically or by just defining 14 alternative approaches. These options are shown in 15 two boxes. If the CCF is not addressed using either 16 of these two options, then it can be addressed using 17 our risk informed approach which is shown in colored 18 box. A review of our risk informed approach is broken 19 down into four steps which is covered in corresponding 20 subsections in Section D3.
21 MEMBER MARCH-LEUBA: Try to speak louder.
22 MR. ALFERINK: I will try to speak louder.
23 (Simultaneous speaking.)
24 MEMBER MARCH-LEUBA: I understand quite a 25 bit, but slower.
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131 1 MR. ALFERINK: I will cover each of these 2 steps in more detail in the following slides. Next 3 slide, please. The first step in reviewing --
4 CHAIRMAN REMPE: Do you have a trade map 5 for us, please? And be really close to where the 6 microphone is. Thank you, sorry.
7 MEMBER MARCH-LEUBA: I can hear him. But 8 if you speak more -- if you don't speak like me but 9 more eloquently.
10 MR. ALFERINK: Hopefully this will be a 11 little bit better now. We'll try this. Let me know 12 if you still have difficulty hearing me, please. The 13 first step in reviewing your risk informed approach is 14 to determine consistency with NRC --
15 MEMBER BROWN: You got interrupted. Why 16 don't you go back (audio interference) --
17 MR. ALFERINK: Sure.
18 MEMBER BROWN: -- so we know where we are.
19 MR. ALFERINK: Okay. So I'm on slide 20.
20 Okay. So this slide illustrates how the staff 21 envisions a risk informed approach getting into the 22 overall D3 assessment process. The D3 assessment 23 process starts by identifying each postulated CCF.
24 Once the CCF is identified, it can get 25 addressed deterministically or by justifying 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
132 1 alternative approaches. These options are shown in 2 the two boxes in the middle. If the CCF is not 3 addressed using either of these two options, then it 4 can be addressed using a risk informed approach which 5 is shown in the colored box on the right.
6 The review of a risk informed approach is 7 broken down into four steps, each of which is covered 8 in the corresponding subsections of the new Section 9 B.3.4. I will cover each of these steps in more 10 detail in the following slides. Next slide. The 11 first step in reviewing a risk informed approach is to 12 determine consistency with NRC policy and guidance on 13 risk informed decision making as described in Section 14 B.3.4.1.
15 This step is provided because 0.2 of the 16 policy explicitly states that the staff will review 17 applications that use risk informed approaches for 18 consistency with established NRC policy and guidance 19 on risk informed decision making. 0.2 of the policy 20 provides Regulatory Guides 1.174 and 1.233 as 21 examples. Reg Guide 1.174 describes an approach that 22 is acceptable to the staff for developing risk 23 informed applications for a licensing basis change.
24 Reg Guide 1.174 also references Reg Guide 25 1.200 which describes an approach for determining 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
133 1 whether a base PRA is acceptable for use in regulatory 2 decision making. As stated in SECY 22-76 is the 3 staff's goal is that the acceptance criteria for risk 4 informed approaches for Digital I&C CCF will be 5 consistent with the NRC's broader practices and 6 guidance for risk informed decision making and not 7 specific to Digital I&C. The staff intends to 8 leverage existing practices and guidance rather than 9 develop an entirely new paradigm for Digital I&C.
10 As such, the review guidance for 11 determining consistency with NRC policy and guidance 12 on risk informed decision making points to current 13 staff review guidance elsewhere, including SRP Chapter 14 19 and DC/COL-ISG-028. Now I will note that SRP 15 Chapter 19 provides review guidance for addressing the 16 principles of risk informed decision making, including 17 defense in depth. Next slide. Now we are on slide 18 22.
19 The second step in reviewing a risk 20 informed approach is to evaluate how the CCF is 21 modeled in the PRA as described in Section B.3.4.2.
22 The reviewer will first determine whether the 23 application is based on the base PRA that meets the 24 PRA acceptability guidance in Reg Guide 1.200 or for 25 guidance from the reactors and reports the plant for 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
134 1 design at the time of application. As part of this 2 activity, the reviewer will evaluate the justification 3 for excluding any hazard or operating mode from the 4 risk informed B.3 assessment as well as any changes 5 made to the PRA model to support the application.
6 The reviewer will then evaluate how the 7 CCF is modeled is in the PRA and the justification 8 that the modeling adequately captures the impact of 9 the CCF on the plant. Because the CCF could affect 10 multiple plant systems or functions, this section 11 specifically notes that the I&C technical reviewer and 12 the risk analyst should coordinate their review to 13 ensure that the application sufficiently addresses the 14 impact of the CCF on plant systems and functions. In 15 general, a CCF can be modeled in the PRA through 16 detailed modeling of the Digital I&C system or the use 17 of surrogate events.
18 MEMBER MARCH-LEUBA: So this is Jose 19 March-Leuba. What is a surrogate event? You assume 20 that the scram fails?
21 MR. ALFERINK: Give me one second.
22 MEMBER BROWN: What did you say?
23 MEMBER MARCH-LEUBA: What is a surrogate 24 event?
25 MEMBER BROWN: Thank you.
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135 1 MEMBER PETTI: I had a question. Typical 2 PRAs, do they actually go into detailed modeling of 3 the DI&C system?
4 MR. ALFERINK: I'm not aware of operating 5 light-water reactors or models that have that detailed 6 modeling. We wrote this to be general enough to 7 account for it if they do.
8 MEMBER PETTI: But the history today is 9 that no one goes into this level of detail.
10 (Simultaneous speaking.)
11 MEMBER PETTI: Although PRAs are the most 12 advanced we have out there.
13 MR. ALFERINK: We tried to write this in 14 general. So should somebody model it in the future, 15 we don't need to rewrite the guidance.
16 MEMBER BROWN: Let me amplify. Can you 17 hear me, Jose? Paragraph 1 and paragraph 3.B.3.4.2 18 says modeling of hardware software components.
19 One limitation is that some PRA models 20 which means all do not include details of various 21 hardware or software components of DI&C systems or all 22 of the interdependencies across all different SSCs.
23 And my observation that modeling software based 24 digital I&C systems is an effort that I can use strong 25 words or softer words and you'll never get there.
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136 1 It's extremely difficult when you've got 500,000 lines 2 of code and other data sources that gets pulled in 3 whether it's (audio interference) driven or whether 4 semi-deterministic.
5 In other words, straight through a routine 6 programming all have a little bit of (audio 7 interference). And I guess one of my concerns by 8 emphasizing the modeling as much and recognizing that 9 I am not a fan of risk informing these designs. I 10 think everybody knows where I'm coming from. I'm 11 worried that people trying to model and then they will 12 be less likely to do it to dampen their enthusiasm to 13 adopt a risk informed process because they really 14 don't know how to model an I&C system in the PRA world 15 (audio interference). Yes, Vesna? Is that Vesna?
16 MEMBER DIMITRIJEVIC: So I'd like to add 17 a few things here. First step, in this slide, the CCF 18 means I&C CCF. The PRA models cause failures and he 19 has a very well developed model.
20 So those models are complicated and 21 include multiple failures, double, triple, quarter, 22 the alpha, beta, gamma factors. In my experience with 23 the advanced reactors and that's connected with VPR.
24 In order to model instrumentation that common caused 25 factors, we have included that in the model.
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137 1 But it is included through the mostly 2 pseudo-guide events which are explained the host of 3 questions that you don't go in this standard, like, 4 four pumps common cause models. But instead of that, 5 you replace the -- you don't have doubles, triples.
6 You just replace common cause digital failure as a 7 non-event. And sometimes that has a specific platform 8 name and you name it. But actually models common 9 cause failure of DI&C.
10 (Simultaneous speaking.)
11 MEMBER MARCH-LEUBA: So you model the 12 common cause failure by assuming the output fails.
13 MEMBER DIMITRIJEVIC: Yes, assuming.
14 (Simultaneous speaking.)
15 MEMBER DIMITRIJEVIC: -- giving to that 16 event specific name instead of going through the 17 common cause approach from the PRA. And what we saw 18 in the EPR that those failures actually strongly 19 dominate the risk. So --
20 MEMBER MARCH-LEUBA: Yeah, my question, I 21 was going to have a follow-up question before we go 22 into details of how implementing is. How can you have 23 a critical safety function that is not risk 24 significant? I mean, it's a famous oxymoron.
25 (Simultaneous speaking.)
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138 1 MEMBER DIMITRIJEVIC: This retelling is 2 not just related to that. It's related to control of 3 the various systems and components in the plant. It's 4 not always related to critical safety functions. You 5 know, it's dependent on the --
6 (Simultaneous speaking.)
7 MEMBER MARCH-LEUBA: You only do the CCF 8 analysis for the critical safety functions.
9 (Simultaneous speaking.)
10 MR. CARTE: So the displays and controls 11 are with respect to the critical safety functions.
12 This is Norbert Carte. CCF is with respect to all 13 functions. It's just the displays and controls for 14 diverse manual action are where we think about 15 critical safety functions.
16 MEMBER MARCH-LEUBA: Can you say your 17 name?
18 MR. CARTE: Norbert Carte, I&C.
19 MEMBER MARCH-LEUBA: I don't really 20 understand the logic. I mean, if something is not 21 risk significant, why do you want to formalize it?
22 It's not critical.
23 MEMBER DIMITRIJEVIC: But you don't really 24 know, Jose, before you really run the models, what is 25 risk significant or not risk significant. And often 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
139 1 some things you don't expect to be risk significant 2 could be risk significant. I am not sure actually 3 also what was said, I mean, because this common cause 4 includes all other functions.
5 Okay. So first -- how can I summarize 6 that? It's definitely not easy and PRA lacks a lot of 7 approaches to model DI&C. I mean, especially, like, 8 say, for operator actions and things like that.
9 But the things being developed and the 10 status of being built and maybe this will improve with 11 time. But that includes to every activation of every 12 system. It's not just a protection system. It's 13 activation of every system and automatically when 14 demanded, safety, non-safety. So it includes every 15 SSC.
16 MEMBER MARCH-LEUBA: So will you explain 17 to me and I know when we were passing, you were having 18 a member of this cache. What's the difference between 19 you seeing these surrogate events where you don't 20 model the digital I&C and you assume it fail. And the 21 deterministic analysis of the same problem, I mean, 22 what is different between the two? Because assuming 23 it fails, so that's the deterministic approach.
24 MEMBER DIMITRIJEVIC: You get it a 25 probability to fail. And then you see how much it 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
140 1 contributes to the total risk. I mean, that's the 2 difference between deterministic and probabilistic.
3 So I mean, I don't know. I'm not sure I understand 4 your questions.
5 MR. CARTE: Norbert Carte. Let me 6 summarize it a little different. So typically when we 7 think of a deterministic analysis, we think of the 8 Chapter 15 accident analysis. And that only looks at 9 the worst events and the most conservative analysis 10 factor.
11 We don't look at all of the events. And 12 based on the outcome of the worst events and analyze 13 in accordance to the criteria if that's acceptable the 14 facility to say. A PRA looks at all events and looks 15 at consequences and likelihoods and does a tabulation 16 across all events.
17 So it looks at beyond design basis 18 accidents. It looks like design basis accidents, 19 AOOs. It looks at everything and considers both 20 consequences and likelihood to arrive at a number 21 where a deterministic analysis basically makes a 22 likelihood determination beforehand and says these are 23 accidents. These are AOOs.
24 And then applies the criteria to that type 25 of event. AOOs shall not cause fuel damage. An 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
141 1 accident shall not exceed certain dose limits, right?
2 So the likelihood is categorical in a 3 deterministic analysis. And then the acceptability is 4 then done deterministically based, so based on 5 consequences. The PRA looks at all the events, 6 likelihood, and consequences.
7 MEMBER MARCH-LEUBA: So let me give you 8 the example of the small break LOCA. You don't run 9 the worst small break LOCA. You run a spectrum of 10 LOCAs. You run them all and pick the worst.
11 MR. CARTE: Yes.
12 MEMBER MARCH-LEUBA: Now from doing this 13 risk analysis, you're saying you're going to look at 14 a likelihood. That means you're going to run the 15 spectrum of possible accidents from the unicycle to 16 the end of cycle with different control patterns, with 17 different loadings, with different -- is it raining or 18 not. And I explain that you don't do that either.
19 MR. ALFERINK: This is Steven Alferink.
20 You would normally just look at one initiating event 21 for the small break LOCA. You don't look through 22 every possible --
23 MEMBER MARCH-LEUBA: Yeah, you do.
24 MR. ALFERINK: -- configuration.
25 MEMBER MARCH-LEUBA: You do a spectrum of 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
142 1 breaks.
2 MR. ALFERINK: You have, like, a small 3 break LOCA, large break LOCA. So you have a spectrum 4 of different initiating events.
5 (Simultaneous speaking.)
6 MEMBER DIMITRIJEVIC: And you have 7 different success criteria for each of them, each 8 system, very quiet to operate in timing and things 9 like that. Those are different scenarios in PRA.
10 MEMBER MARCH-LEUBA: Let me check your 11 sound. Say something.
12 MEMBER BIER: Hi, Jose.
13 MEMBER MARCH-LEUBA: No.
14 MEMBER BIER: Okay. Should I come over 15 here?
16 MEMBER MARCH-LEUBA: Come closer.
17 MEMBER BIER: I'm going to take a stab at 18 a slightly different answer. Okay. I'm going to take 19 a stab at a slightly different answer to Jose's 20 question and see whether I'm understanding it right 21 and whether it helps. I think the deterministic part 22 would be deterministically saying this I&C system 23 fails with probability 1.
24 And the probabilistic part would be all 25 the rest of the plant PRA model. What happens if you 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
143 1 don't have the I&C model and what's this I&C system 2 and what's the chance that would lead to core melt?
3 Is that close?
4 MR. CARTE: Yes. So we essentially 5 envisioned a sensitivity analysis. Calculate your CDF 6 or whatever your risk metrics are. Postulate a 7 failure with a probability of one. And then determine 8 how much your risk metric changes. And that's a 9 sensitive analysis to determine the risk to gauge the 10 risk of the CCF.
11 MEMBER BIER: Okay.
12 MEMBER ROBERTS: I had a question similar 13 to Jose's. Let me try an example and see if this 14 captures Jose's question and maybe to answer it. So 15 you have a reactor scram system, and so if you have no 16 diversity because you're looking for alternatives to 17 diversity, and your PRA would assume with a 18 probability of one that there's no scram to run your 19 plan events. And if your change in CDF were large 20 which I would think it probably would be, if the scram 21 failed, then you wouldn't be able to use the risk 22 informed approach. But now you're stuck with adding 23 diversity or coming up with some other explanation.
24 MR. ALFERINK: I'll get to that in a few 25 slides.
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144 1 MEMBER BROWN: That's assuming -- what 2 you're saying is you assume all four channels don't 3 work. And therefore, you don't scram.
4 MEMBER ROBERTS: Right. You assume a 5 common cause failure. You assume you can't model.
6 MEMBER BROWN: You don't have any 7 diversity.
8 (Simultaneous speaking.)
9 MEMBER ROBERTS: You can't model the 10 details, so you have to assume there's no scram. But 11 I would imagine someplace you could run through the 12 risk model and say, well, if I don't scram, I'll still 13 have a satisfactory low CDF. But then you wouldn't 14 have metric critical safety function. Now you're 15 starting to cross the line into deterministic space 16 which you find a critical safety function because you 17 thought that was important. But is that a potential 18 outcome that you conclude fails to scram is okay as a 19 consequence?
20 MR. CARTE: It's hard -- Norbert Carte.
21 So it's hard to imagine for a light-water reactor. I 22 have heard some molten salt reactor designs where the 23 Doppler coefficient is large enough that you don't 24 need a short scram, a postulated scram in two hours.
25 So it is possible for some designs. There 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
145 1 is that possibility, yes. But I don't see it for 2 light-water designs yet.
3 MEMBER ROBERTS: That was a question I 4 plan to ask in a couple of slides. It probably comes 5 into play if you conclude at the critical safety 6 function of scram that's not risk significant. Then 7 that would require you to go through the five 8 principles in the Reg Guide 1.174 which talks about 9 safety margins and the defense in depth and 10 regulation, those kinds of things.
11 And I would think it would be hard to come 12 through that screen with a fail to scram. And then 13 conclude that it really was risk informed to have that 14 as an acceptable consequence. Is that right?
15 MEMBER MARCH-LEUBA: We've seen some 16 designs on the new reactors where the control rods are 17 not safety grade.
18 MEMBER ROBERTS: But then would the scram 19 be a critical safety function?
20 MEMBER MARCH-LEUBA: It's not. It's 21 because there is either expansion in the sodium 22 reactors or the temperature coefficient in the silicon 23 carbide. And you just don't need to scram.
24 MEMBER ROBERTS: But I read the BTP. I 25 end up wondering just like Jose is asking how you 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
146 1 would ever use risk informed option because either you 2 could've gone through the deterministic approach and 3 your best estimate analysis would show that you have 4 adequate diversity. Or you'd have to show that the 5 consequence didn't warrant diversity or you wouldn't 6 pass the risk informed. Didn't seem like there was 7 any path that you could actually get to the end using 8 the risk informed doc.
9 MEMBER MARCH-LEUBA: My concern is that 10 the risk informed would be misused. It will not be 11 done thoroughly and scientifically. And somebody 12 would conclude that, hey, I don't need diversity.
13 MEMBER PETTI: But that's on the staff for 14 them to view.
15 MEMBER MARCH-LEUBA: Yeah, but once -- I 16 wouldn't say it on the record. Well, let's say once 17 something is submitted is very rare it gets rejected.
18 MEMBER BROWN: What did you just say?
19 MEMBER MARCH-LEUBA: Once something is 20 submitted for review, it very rarely it gets rejected.
21 Sometimes it gets tweaked. But rejected --
22 MR. DARBALI: Well, I could add. So as we 23 -- this is Samir Darbali. We were developing the SECY 24 and later working on the BTP, we're looking at real 25 examples of how this could be applied.
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147 1 If you go back to the Oconee design, there 2 were two functions that required a diverse automatic 3 systems, the high and low safety injection. At the 4 time, this was in 2003, 2005, the applicant actually 5 wanted to use risk information to say why manual 6 actions could be taken later than the minimum required 7 that would trigger a DATS (phonetic). At the time, 8 the staff did not accept that risk informed argument.
9 So the licensee ended up installing to 10 DATS. That's an example of where this, a risk 11 information could say, well, if manual action was 12 taken much later than was required by the game 13 attackers analysis, would the plan be still safe?
14 We're not talking about reactor shutdowns. We're 15 talking about safety injection. And maybe a risk 16 argument could be used to justify a manual action be 17 taken later rather than -- it's still a diverse means.
18 But they're not installing a diverse automatic system.
19 MEMBER MARCH-LEUBA: I'm not a big fan of 20 PRA. But for you to do a risk informed analysis like 21 this, you will need to evaluate every single day in 22 the site. Every single possible scenario and then 23 figure out what is the bell distribution and peak 24 theorem, you can tell.
25 You're not doing that. I've never seen 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
148 1 anybody do that. When you put in the PRA, the PRA 2 takes us the input to Chapter 15 results which is the 3 worst case.
4 MEMBER BROWN: We are digressing into the 5 general benefits or non-benefits of PRAs in general.
6 The fundamental point we were talking about, we were 7 talking about (audio interference) to the modeling of 8 CCF of these Digital I&C systems. Modeling the CCF 9 with the Digital I&C systems, and we haven't really 10 come to a conclusion on how you really model them 11 other than Vesna's comment on the surrogate approach.
12 You just assume it doesn't work. The end product 13 (audio interference) does not work.
14 MEMBER MARCH-LEUBA: Yeah, we're kind of 15 missing you, Charlie.
16 MEMBER DIMITRIJEVIC: To explain to this 17 would take a long time and is much more complicated to 18 that. Jose, I wouldn't really worry because those 19 events are extremely important in the PRA. So I would 20 really worry more about the deterministic principles 21 like if we look in the 1.883 which we are looking at 22 this that I would miss things. So just don't worry.
23 The PRA will cover this if it's modeled right.
24 MEMBER BROWN: Okay, Vesna. We need to be 25 getting off of the PRA in general, the goodness of the 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
149 1 PRAs. I got that. I think we need to proceed on.
2 The issue is roughly on the modeling.
3 MEMBER ROBERTS: Can I have one follow-up 4 question to Samir? The Oconee example, did the 5 Section 3.2.2 in the BTP apply that? Because there's 6 a whole provision for crediting manual operator action 7 in the existing BTP.
8 MR. ALFERINK: Right. And I wasn't 9 involved in that. But I believe --
10 MEMBER BROWN: Neither were we.
11 MR. ALFERINK: So the issue with manual 12 (audio interference), it has to be performed in a 13 timely manner. So Oconee for all of their other 14 functions, they credited diverse manual actions that 15 could be performed in a timely manner. Those two that 16 require a diverse automatic system would be they 17 cannot do it in a timely manner before we begin the 18 packers analysis.
19 That automatically triggered you needed 20 that. They wanted to provide a risk argument why they 21 didn't need to. But at the time, the staff did not 22 accept that.
23 MEMBER ROBERTS: So (audio interference).
24 So the scenario, best estimate methods couldn't show 25 that it was okay. But the probability of going down 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
150 1 that branch was low enough to screen it out 2 essentially what would happen.
3 MR. ALFERINK: Right. That would've been 4 --
5 (Simultaneous speaking.)
6 MEMBER ROBERTS: Okay. I understand. So 7 that would've been less than the delta CCF, ten to the 8 minus six, whatever the criterion is in delta LERF.
9 Okay. That makes sense.
10 MR. CARTE: Norbert Carte, I want to parse 11 a little bit best estimate and risk informed. So one 12 approach to best estimate is that leak before break.
13 So that's not necessarily risk informed. But it's a 14 best estimate argument.
15 So some people argue you'll get leak 16 before break. And therefore, you have time to for 17 manual action. So that's a different way that a best 18 estimate might come in, and it's not just an issue 19 about risk informed.
20 MEMBER MARCH-LEUBA: I apologize for 21 having taken us on a branch. So please continue.
22 MR. ALFERINK: I was actually worried 23 about to answer your question. So I was going to note 24 that certain events can be existing basic events in 25 the PRA or new basic events added to the PRA that 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
151 1 capture the impact of the CCF on the plant. That's 2 it. Now we're on slide 23.
3 The third step in reviewing a risk 4 informed approach is to determine the risk 5 significance of the CCF as described in Section 6 B.3.4.3. This section provides guidance on reviewing 7 the risk significance of a CCF obtained using either 8 a bounding sensitivity analysis that assumes that CCF 9 occurs or a sensitivity analysis that uses a 10 conservative value less than one for the probability 11 of the CCF. Since this is a rather long description, 12 I use the term conservative within quotation marks on 13 the slides to refer to the second type of sensitivity 14 analysis.
15 When a risk informed approach uses a 16 bounding sensitivity analysis, the reviewer will 17 evaluate the baseline risk that was used to determine 18 the increase in risk that does not need to evaluate 19 the justification of the probability of the CCF. As 20 we have stated in previous ACRS meetings, the staff is 21 open to considering values less than one for the 22 probability of the CCF with appropriate justification.
23 And these values may vary from system to system 24 depending on the design.
25 The staff does not currently have a 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
152 1 technical basis for a value less than one for the 2 probability of the CCF and is applicable to all 3 designs. So an application that uses a value less 4 than one needs to provide additional justification.
5 When a risk informed approach uses a conservative 6 sensitivity analysis, the reviewer will evaluate the 7 technical basis of the conservative probability of the 8 CCF which demonstrates that defense in depth is 9 addressed. As part of this activity, the reviewer 10 will evaluate the impact of this assumption on PRA 11 uncertainty, including a determination of whether this 12 assumption is the assumption.
13 MEMBER ROBERTS: Yeah, this is where I 14 planned to ask a question about the five principles in 15 Reg Guide 1.174. And one of the principles is defense 16 in depth, right? So any risk informed change has to 17 be justified with the defense in depth.
18 I wasn't clear why you addressed defense 19 in depth for this one specific exactly which in light 20 of the follow-up question is there's also requirements 21 for safety margins and maintaining consistency with 22 regulations and having a monitoring program and all 23 those things that show more than just Reg Guide 1.174 24 but pretty much any principle in risk informing. So 25 I guess it's two questions. One is why is defense in 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
153 1 depth in here when it should always be. And then what 2 about the other principles?
3 MR. ALFERINK: You're correct. So that's 4 why a few slides back I talked about 1.174 and the 5 principles. Yes, we always address those (audio 6 interference). Here I would argue that this has 7 additional emphasis.
8 There is a note in the SECY. Let me find 9 the exact wording here. But essentially it says the 10 staff does not intend to (audio interference). It's 11 just based on reducing the probability. So this is 12 added emphasis that you need to consider defense in 13 depth, not just it has a low probability. So it 14 argues additional emphasis on that point.
15 (Simultaneous speaking.)
16 MR. ALFERINK: That's right. It goes in 17 the SECY.
18 MEMBER BROWN: (Audio interference).
19 MEMBER ROBERTS: Just a suggestion to 20 think about covering principles, in the BTP just to 21 make clear what you mean when you reference 1.174.
22 MR. ALFERINK: Next slide, again, slide 23 24. Both type of sensitivity analyses, the reviewer 24 will evaluate if the quantification accounts for any 25 dependents that are introduced by the CCF --
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154 1 dependencies that are introduced by the CCF, including 2 the ability for operators to perform main watches. An 3 example of this situation for operating reactors, 4 there's a CCF associated with the upgrade from analog 5 to digital control room annunciators where the CCF may 6 not disable protective function.
7 But it could impact the operator's ability 8 to respond. It is important to note that the purpose 9 of the sensitivity analysis is to determine the risk 10 significance and the importance of the CCF, not the 11 baseline risk with a digital I&C system. For the 12 example of an operating reactor that is replacing an 13 analog I&C system with a digital I&C system, the 14 sensitivity analysis does not calculate the change in 15 risk between the (audio interference).
16 With that said, a reviewer will evaluate 17 the sensitivity analysis to determine if the CCF is 18 risk significant or not. The CCF is not risk 19 significant if the increase in CDF in the sensitivity 20 analysis is less than one times ten to the negative 21 six per year and the increase in LERF from the 22 sensitivity analysis is less than one times ten to the 23 negative seven per year. The increase in CDF and LERF 24 are used in Reg Guide 1.174 for licensing basis 25 changes. So their selection satisfies the staff's 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
155 1 goal that the acceptance criteria for risk informed 2 approaches or Digital I&C CCF will be consistent with 3 the NRC's broader practices and guidance for risk 4 informed decisions.
5 MEMBER PETTI: So just a comment. You've 6 been discussing about why whether or not this BTP 7 (audio interference). That metric makes it (audio 8 interference) because LERF and CDF may not be 9 applicable (audio interference).
10 CHAIRMAN REMPE: But I would go further as 11 I mentioned earlier saying that some of the advanced 12 small modular LWRs increase core damage frequency less 13 than one times ten to the minus six if they're down to 14 ten to the minus eight. That could be a problem.
15 This was -- again, we elaborated on this years ago.
16 But there was a little plot we included in the letter 17 that talked about that we were advocating --
18 (Simultaneous speaking.)
19 CHAIRMAN REMPE: So I hesitate to have 20 something like that in there.
21 MEMBER ROBERTS: Yeah, I suggest the other 22 core principles in the Reg Guide are important there 23 in degradation safety margins because you increase 24 your CDF by a factor of 100. And that will seem to 25 come out of the principles.
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156 1 CHAIRMAN REMPE: Yeah, you'd hope so.
2 MEMBER ROBERTS: Not to beat that. But 3 that probably belongs in a slide like this. It's not 4 risk significant if the five criteria are met, 5 including the other four principles.
6 CHAIRMAN REMPE: Yeah.
7 MEMBER ROBERTS: So these are no 8 sufficient. These are necessary maybe, but not 9 sufficient to call it not risk significant.
10 MR. ALFERINK: And in order to get this 11 point, you would already --
12 (Simultaneous speaking.)
13 MEMBER ROBERTS: We've had defense in 14 depth, safety margins, either regulations or have an 15 exemption, those types of things.
16 MEMBER MARCH-LEUBA: Okay. Going back to 17 my favorite topic, I need to repeat again. Let's 18 assume we are talking about the protection system.
19 And you're trying to protect something that if it fail 20 we have a CDF greater than ten to the minus six.
21 The only way you're going to have a risk 22 informed evaluation and determine that the CCF doesn't 23 cause a CDF greater than ten to the minus six is 24 because the probability of the CCF, the frequency is 25 very small. Ten to minus three, ten to minus four, 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
157 1 ten to minus five. But you don't want to do a PRA of 2 the control system.
3 So how do you know what is the frequency 4 of the CCF? I'll take one, yes. That's conservative.
5 You take a number lower than that, you need to justify 6 it. You justify, you have to have a detailed PRA of 7 the system.
8 And nobody has the PRA of software common 9 cause failures. You need to come closer. I can't 10 hear you from there.
11 MEMBER BIER: I didn't say anything yet.
12 I can just stand here, I think. I don't think you 13 need necessarily a PRA of this system to justify an 14 estimated CCF probability less than one. There might 15 be grounds to say based on expensive testing and 16 operating experience under a wide variety of 17 circumstances. We think it's less than 0.2 or 18 something but it's not high.
19 MEMBER MARCH-LEUBA: And that's my --
20 MEMBER BIER: So it's subjective.
21 MEMBER MARCH-LEUBA: And that's my general 22 objection to PRA because when I look at the fault 23 trees, almost everything has a failure probability of 24 ten percent. But you don't know what it is. I mean, 25 if you look underneath the PRA, the result always has 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
158 1 four significant entries. But you look at the input, 2 90 percent of the input is 10 percent.
3 DR. BLEY: You're making stuff up now, 4 Jose.
5 (Simultaneous speaking.)
6 MEMBER PETTI: Let's keep moving, please.
7 MEMBER DIMITRIJEVIC: Yeah, let's not make 8 this about Jose. And if we add Charlie, then we are 9 really in trouble. 74 is applicable for you here.
10 It's really for operating fee. It's for the plant 11 change.
12 And here we are sort of also very liberal 13 on defining what the change is. And so therefore you 14 should be using something which even advanced reactors 15 will be using something which, for example, 10 CFR 16 50.69 rely of the ranking of the SSCs. And not to be 17 based on the Reg Guide 1.174.
18 This is not -- I don't think that this is 19 a good application for this guide. So I think you 20 should consider the different documents on the -- I'm 21 just trying to think. I think it's NEI document of 22 determining the importance of SCCs. But I don't 23 remember at this moment that number.
24 (Simultaneous speaking.)
25 DR. BLEY: This is Dennis. And I think 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
159 1 we've talked about this before. But you're absolutely 2 correct about the purpose 1.174. But the principles 3 on which it's based are applicable in other cases, and 4 I think that's what they're suggesting here. Maybe 5 they could say a little bit more about that.
6 MEMBER DIMITRIJEVIC: Dennis, it was never 7 -- like, for example, some of the advanced plans 8 changed this criteria based on the CDF. This is so 9 specific for the coolant experience on the CDF which 10 we saw. So that's why I will try. I'm not sure 11 actually that the Zenith C (phonetic) have the better 12 document for that. But it has to be somewhere because 13 10 CFR 50.69 is based on (audio interference).
14 MR. WEERAKKODY: This is Sunil Weerakkody, 15 senior level advisor for PRA in NRR. So first off, I 16 want to agree with Vesna, her statement that 1.174 17 appears to be not applicable here because we use it to 18 review and approve those changes. But I'm going to 19 say a couple of things.
20 I'm sure Vesna would understand she's been 21 in the PRA as long as I have. What we did here was we 22 recognized that the more appropriate parameter to find 23 the significance of this common post-failure is 24 something called risk achievement work which you see 25 in 50.69. However, for a couple of reasons, we found 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
160 1 we can correlate that to the change in CDF.
2 If you think about how that parameter is 3 computed, risk achievement work, it's very much 4 related to the change in CDF. And we prefer that 5 approach because we have to come up with a greater 6 approach to make decisions and going with the delta 7 CDF approach using Reg Guide 1.174 is more amenable.
8 And that's why we chose it. But I do agree with you, 9 Vesna, that in terms of starting out with assessing 10 the significance, the risk achievement work is the 11 better parameter.
12 MEMBER DIMITRIJEVIC: Yeah, you know this 13 risk achievement, the problem is there between 14 absolute and relative. And this is the PRA 15 discussion. That has not been so for the new fleet.
16 So I don't really know. Is it going to be 17 new document or maybe new version of 1.174 or maybe a 18 general one which can be applied for advanced 19 reactors? I mean, I don't know. But I think it's 20 like in this moment, it's sort of the -- putting it 21 here is not going to work for advanced reactors.
22 MR. WEERAKKODY: Again, this is Sunil. I 23 do agree. This may not work for advanced reactors 24 which will have other risk metrics other than CDF, 25 yes.
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161 1 MEMBER DIMITRIJEVIC: You mean if they 2 have a CDF of ten to minus nine. If you are allowed 3 an increase of ten to minus six, then you're talking 4 about a factor of thousand. And then is that 5 acceptable or not? I mean, that's what I said, 6 relative and absolute. So I mean, it doesn't have to 7 be just non-light water reactor. But light-water 8 reactor with very small core damage.
9 MR. WEERAKKODY: This is Sunil Weerakkody 10 again. I'll be like a politician. I don't answer 11 speculating those questions. So I don't know what 12 would happen with the advanced light-water reactors.
13 But definitely this will, for the light-14 water reactors and even the advanced light-water 15 reactors -- one of the things I will clarify is that 16 even with the advanced light-water reactors whose core 17 damage frequencies are low like ten to minus eight.
18 When you fail a system like RPS, it's going to make a 19 big jump up.
20 So I think we will catch that with some of 21 the exceptions. So again, we haven't done those 22 calculations. But I know we have done a number of 23 calculations actually offering the number of 24 calculations using our models to get at -- to look at 25 how the different systems would fare if we fail the 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
162 1 CCF.
2 CHAIRMAN REMPE: But you may be relying on 3 non-safety related equipment --
4 MR. WEERAKKODY: Yes.
5 CHAIRMAN REMPE: -- if you had a failure 6 --
7 (Simultaneous speaking.)
8 MR. WEERAKKODY: Correct, yes, yes.
9 MEMBER BROWN: Why in the world do you 10 think -- why in the world don't you think that -- why 11 do we design the systems the way we do? I mean, we 12 got four channels. You can incorporate some 13 diversity. I don't do great big analysis. It's going 14 to cost me three or four or five million dollars to 15 get finished in several years. Okay?
16 And I've got four channels in. Now I have 17 got a design that has been proven for 70 years to work 18 kind of just fine. And now we want to risk inform the 19 design of these systems for whether it's not light-20 water or light-water.
21 I mean, your point is correct. If the 22 whole RPS fails, that's why we have the (audio 23 interference) independence, the control of access, 24 predictable, repeatable performance out of it, the 25 five principles. I mean, we argue and promote those, 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
163 1 and they work well.
2 So I mean, I'm going to default early that 3 I was a manager in a plant and we were going to 4 upgrade to a Digital I&C system. The last section I 5 would use would be 3.4. I would use -- and I put the 6 processors in there, two FPGAs or have a couple just 7 to make everybody happy, even if I didn't believe it 8 was necessary.
9 It just -- it boggles my mind a little bit 10 about where we're going. I mean, I totally agree with 11 Jose and I agree with Vesna. I mean, I don't know all 12 the details of 1.174. I'm a total neophyte when it 13 comes to between she and Vicki.
14 But from building -- for spending 35 years 15 building stuff and actually putting it in shifts, it 16 doesn't get any easier (audio interference). And 17 those are engineering judgments. The reason we have 18 four vice three.
19 We actually had plants that only had three 20 channels. We had plants for some functions we only 21 did two. We found out reliability wasn't very good if 22 you wanted to do a startup and you only had two 23 intermediate range channels.
24 So we made four. So the ships, they're 25 out at sea. They got to operate. Commercial plants 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
164 1 are on the land. They're different. So you have a 2 different strategy that you use when you approach how 3 you implement redundant systems.
4 But for the major critical safety systems 5 which RPS safeguards systems and, well, that's about 6 it. I mean, you cover those with these principles, 7 you've covered them. You can't have redundant reactor 8 control systems.
9 You can't have them fighting each other.
10 One has to control or the other. So you can't have 11 two voltage regulators governing a generator. You got 12 to have one or the other (audio interference).
13 MEMBER BIER: I have another question for 14 staff that might clarify at least my thinking, maybe 15 some other people's thinking. We're talking a lot 16 about I&C for scram and what if you got scram failure.
17 There's a ton of I&C out there, everything from tiny 18 test lines that probably don't appear in the PRA 19 anywhere because they're only used in maintenance to 20 actuation of an individual pump or whatever. So what 21 is the scope of applicability of this? And maybe 22 there's a lot of cases where it might be more 23 applicable than just for scram.
24 MR. CARTE: Norbert Carte, I&C. So we're 25 focusing mostly on RPS and ESFAS. And the reason is 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
165 1 because the concern is that there's not enough time to 2 do things manually. And you have certain automatic 3 actions for RPS and ESFAS. And you evaluate those 4 automatic actions.
5 And presumably, you have those automatic 6 actions because there is not time to do a reliably by 7 hand. And in those cases, their failure would be a 8 problem. And that's why you evaluate the failure of 9 those automatic protective actions. The other 10 actions, presumably you have more time to do them 11 manually and therefore -- and there's more diverse 12 ways to do that. But the CCF was really a concern 13 always for the automatic protective actions rather 14 than all the actions.
15 MEMBER MARCH-LEUBA: Before you get 16 discussion, let me put something on the record. If 17 you have an action that from the deterministic 18 analysis, you find out you can't survive. And you 19 decide to go risk informed. In my mind what you're 20 telling me is trust me CCF is not going to happen.
21 Because if it were to happen, it would be 22 bad. That's what risk informed does. Trust me CCF 23 will happen. And that's not under discussion.
24 Charlie, speak loudly.
25 MEMBER BROWN: Yes. Excuse me, but we are 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
166 1 going to have to move on because we need to wrap this 2 -- we've got a few more slides to go. We're not going 3 to resolve this PRA, non-PRA risk 1.174 in this. It 4 has raised some issues, but I'm going to suggest that 5 we move on.
6 And then because I know Tom wants to make 7 a few other comments he wants to at least read in and 8 I've got a few I want to just bring up. They're not 9 as broad and expansive and heart throbbing as these 10 are. Just some questions of why here is not there 11 type things. So why don't you go ahead and finish the 12 slides. We've only got seven or eight more slides 13 (audio interference) 32, something like that.
14 MR. ALFERINK: Samir already covered the 15 rest of what I was going to cover on this slide. So 16 it you go to slide 25, please. So slide 25 now. The 17 fourth step in reviewing your risk informed approach 18 is to determine appropriate means to address the CCF 19 as described in Section D.3.4.4.
20 This slide illustrates a graded approach 21 for the review based on the risk significance of the 22 CCF. The risk significance of the CCF is 23 characterized by mapping its increasing risk to the 24 regions in Reg Guide 1.174. This figure illustrates 25 this process based on CDF.
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167 1 A similar figure would illustrate this 2 process based on (audio interference). If the CCF is 3 not risk significant meaning the increase in risk 4 falls in Region 3, the reviewer should conclude that 5 standard design and verification and validation 6 processes are sufficient to address the CCF. If the 7 CCF is risk significant meaning that the increase in 8 risk falls in Regions I or II, the reviewer will 9 evaluate the CCF against the acceptance criteria in 10 Section B.3.1.3 commensurate with the risk 11 significance of the CCF.
12 MEMBER ROBERTS: I want to ask you about 13 that. The diagram shows a bubble in Region I. And 14 the text you just read out of the BTP also talked 15 about Region I. Reg Guide 1.174 says applications 16 that result in an increase in CDF above ten to the 17 minus five per year, i.e., the increase of Region I 18 would not normally be considered. So --
19 MEMBER BROWN: Will not normally --
20 MEMBER ROBERTS: Will not normally be 21 considered. So basically, Reg Guide 1.174 is saying 22 if you're in Region I, you're really not risk 23 informed. I guess you could try anything. But the 24 NRC staff says you normally won't consider changes in 25 Region I. So I was trying to figure out why the BTP 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
168 1 is kind of encouraging changes from Region I.
2 MR. ALFERINK: So it's a different --
3 you're really measuring two different things. So for 4 1.174 you're looking at licensing basis change. That 5 will be the change in risk associated with that 6 licensing basis change.
7 Here we are using this figure and we're 8 looking at the risk to the CCF. How much will risk 9 change if the CCF -- if you put the Digital I&C system 10 in. Digital I&C system is in there. If the CCF 11 occurs, how much does this risk change?
12 MEMBER ROBERTS: So you're trying to 13 justify an alternative to diversity which seems to me 14 like the same thing as what Reg Guide 1.174 is going 15 after for any change.
16 MR. ALFERINK: 1.174 doesn't assume that 17 the failure occurs. That would be here's your current 18 plan. You have this licensing basis change. How much 19 of the risk change from where you are now to what 20 you're proposing?
21 The intent here is you put your Digital 22 I&C system in with risk significance if the CCF 23 occurs. What is the change in (audio interference)?
24 So, we use the same graph. It's really two different 25 things that you are looking at.
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169 1 MR. VASAVADA: This is Shilp Vasavada.
2 I'm with the NRC.
3 MEMBER BROWN: Can you hear him, recorder?
4 MEMBER MARCH-LEUBA: Yeah.
5 (Simultaneous speaking.)
6 MR. VASAVADA: Shilp Vasavada with the 7 NRC. So I think what Steve said to put it 8 differently, 1.174 usually is used for licensing basis 9 changes where you have the (audio interference) PRA, 10 both for the baseline and for the change. You would 11 have a failure probability which is mostly coming from 12 operating experience of the data to use in the base 13 PRA as well as the change.
14 And then you make the decision 15 accordingly. And Region I, the guidance over there 16 would apply. Over here, we are using this as a 17 sensitivity.
18 You're using a bounding (audio 19 interference) probability of one to say, okay, what's 20 the worst case that can happen in the CCF -- Digital 21 I&C (audio interference). It's different. You can 22 say mindset because that's not how the (audio 23 interference) operator plant will continue to function 24 even after the Digital I&C changed.
25 We don't expect guaranteed failures. So 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
170 1 because of that different approach, the sensitivity 2 that we are using with gauge what's the maximum worst 3 case risk that can occur. And also the desire to have 4 -- to put, in other words, a performance-based 5 approach where we can grade how much the Digital I&C 6 design techniques can be used.
7 We use this type of guidance. We are 8 proposing this type of guidance. Region I, the 9 Digital I&C techniques would have to be stronger. But 10 we are using sensitivity rather than the way 1.174 11 usually does it.
12 MEMBER ROBERTS: You're saying you're not 13 really in Region I because the CCF probability is not 14 as bad as your modeling? That's what I thought I 15 heard.
16 MR. VASAVADA: So in reality, you don't 17 expect obviously guaranteed failures. So this is 18 trying to, like, what's your upper bound. What's the 19 worst that can happen, because we don't know the 20 actual numbers. And yes, that's the concept, the 21 (audio interference) operator plant would not have a 22 failure probability of one. Or it's not expected to 23 have failure.
24 MEMBER BROWN: The non-PRA CDF guide black 25 is bad and you shouldn't do risk approaches. And the 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
171 1 other white is where CDF is such and such that a risk 2 means you're good --
3 (Simultaneous speaking.)
4 MR. ALFERINK: For that figure, that is 5 the change in risk associated with the licensing basis 6 change. So the actually figure from Reg Guide 1.174.
7 So yes, if you're actual risk increase is in the black 8 area, then yes, we would generally not approve that.
9 What we're trying to do here is (audio interference).
10 MEMBER BROWN: (Audio interference) CDF 11 below like in black you're using above to --
12 (Simultaneous speaking.)
13 MEMBER MARCH-LEUBA: It's ten to the 14 minus.
15 MR. ALFERINK: Black is bad.
16 MEMBER BROWN: That's what I thought. So 17 I got it right the first time. I'm back designing 18 systems.
19 MEMBER DIMITRIJEVIC: Let's make an 20 attempt in this. This is why I thought that this Reg 21 Guide is not good. The Reg Guide calculates if you 22 want to change something in your licensing basis.
23 Let's say instead of taking this (audio 24 interference) out for seven days, you want to take it 25 for two weeks. And then you calculate the change in 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
172 1 the CDF. How they're using it here is to determine is 2 the common cause of that specific thing important.
3 So let's say that I can totally neglect 4 diversity and I'm not trying to eliminate the common 5 cause. So that common cause become a very high 6 probability. What's the change in the risk?
7 And the change in the risk is high. It 8 says, oh, make sure we have a diversity. Make sure 9 that's not going to happen.
10 So there they're using it to determine the 11 importance of that common cause. That's how it is 12 used. But because the original use is different, it's 13 confusing.
14 MEMBER ROBERTS: Yeah, Ryan. That kind of 15 goes to the question I was guessing on the next slide 16 which is 3.1.3 which (audio interference) what you do.
17 It basically says, go concoct an argument and try to 18 sell it. That's what I read of 3.1.3.
19 It doesn't really say anything about the 20 risk information. Oh, I guess that's a factor in the 21 case you put together. But will that make 3.1.3 22 wrong? That's what it seemed to say is come up with 23 a case and we'll see if we like it (audio 24 interference).
25 MR. CARTE: Norbert Carte, essentially 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
173 1 correct.
2 MEMBER ROBERTS: I'm not sure with the 3 risk information. Really it's just it's another tool 4 in their tool kit to try to convince you that they 5 brought you a good (audio interference)?
6 MR. CARTE: Yes.
7 MEMBER BROWN: Can we go to slide 26?
8 MEMBER MARCH-LEUBA: Yes.
9 MR. ALFERINK: With that, I'll turn to 10 Norbert.
11 MR. CARTE: So next slide, please. So 12 essentially there are two pathways. So if they submit 13 a topical report and it gets approved, then they would 14 need to follow the topical report. And you would have 15 to make sure it's applicable, that it's followed and 16 any deviations are justified.
17 But the approval of the topical report 18 would be in the topical report. But if they propose 19 a new application, yes, they have to justify it. So 20 the is essentially, yes, a performance, they state 21 their goals.
22 For this risk category, these are our 23 measures and this is why those measures are added.
24 And yes, they act to develop them. We had considered 25 alternatives.
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174 1 And so if you look at standards like IEC 2 61.508 and its derivatives are 513. What you have is 3 you have measures applied based on reliability because 4 the standard doesn't really know the risk associated 5 with a particular application. And the higher the 6 reliability, the more measures you need to apply.
7 So we could adopt something like that.
8 But those standards are all very prescriptive in the 9 sense of particular measures and particular 10 reliability. And so it's not as flexible as this 11 approach.
12 And yes, it's kicking the can down the 13 road a little bit because you have to explain what 14 you're doing and why. Now one argument I would have 15 with some of the ways the PRA discussions are framed 16 is we would hope that the PRA would be used to 17 evaluate the risk of various designs, not to justify 18 not installing diversity based on risk, right? So if 19 you look at segmentation, independence, and things 20 like that, the more you break a design up in the 21 independent redundant pieces, the less risk 22 significant each individual piece is.
23 And therefore, you can reduce risk simply 24 by partitioning and segmentation and use of 25 independence. And there are various ideas that have 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
175 1 been proposed. For instance, in the EPR design which 2 was never approved but it was done on -- one, it's the 3 standard (audio interference) approach is there's 4 already functional diversity in the light-water 5 reactor designs or for trip functions and for some ESF 6 functions.
7 So their choice was to have two separate 8 safety -- partition the reactor trip system into two 9 separate safety-related boxes. And each box has 10 either a primary or an alternate trip, either 11 anticipatory or a backup trip. And in that way, they 12 had them connected which we had an issue with.
13 But if they were truly independent, then 14 that would be -- you could argue that the risk of one 15 box failing is less because the other box would catch 16 the event. So our hope -- bad word -- is that you use 17 the PRA to evaluate the designs and improve the design 18 and argue that this design is more effective rather 19 than justifying not having diversity based on a risk 20 number. And that is always the risk that you run 21 into, that someone just says, well, it's low risk.
22 Therefore, we don't need to do anything.
23 No, use the PRA as it was originally 24 intended to, to evaluate the relative worth of 25 different design techniques. If you do this, this is 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
176 1 the risk. If you do that, this is the risk. So this 2 is a better approach.
3 MEMBER BROWN: I'll just interrupt you 4 because we're going to need to move on some more. But 5 the segmentation partitioning is almost, like, 6 redundancy having independent channels (audio 7 interference). And then your segmentation is suspect 8 or your partitioning is suspect. So there's a bunch 9 of regular rules you have to follow that have nothing 10 to do with anything other than maintaining 11 independence.
12 MEMBER MARCH-LEUBA: Yeah, I thought we 13 were talking about common cause failure. So when one 14 fails, the other does too.
15 MR. CARTE: Well, common cause still has 16 a vector in some sort if you have different functions.
17 So the question is that's where you have to justify 18 what are the vectors. Do you believe that the real 19 time operating system on your PLC is going to fail at 20 the same time as both systems?
21 Do you believe that the platform software, 22 whatever it is, AC 160 or whatever, is going to fail?
23 Do you believe it's the application program that's 24 going to fail? So what is the source of the CCF and 25 have you adequately addressed that as a source?
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177 1 MEMBER MARCH-LEUBA: Let me start by 2 agreeing with you with your previous statement that 3 PRA should be used for (audio interference). I 4 disagree with your former statement or the latter 5 statement in the sense that if you're telling me trust 6 me, CCF is not going to happen. And you're not 7 willing to do the full PRA to prove that.
8 You're saying, trust me. Obviously, it's 9 not going to happen. Come on, guys. How is it going 10 to happen? That's what I'm hearing.
11 MEMBER BROWN: Yes, but there's a bunch of 12 different arguments. If you look at a four channel 13 system. Say you had the same software, the same 14 processed. Independent data coming into all of them.
15 But if you run it asynchronously means 16 that data is not arriving. If you're getting bad 17 data, the bad data is not arriving at the same place 18 all at the same time. You may never even see the bad 19 data.
20 And so that would be an argument.
21 Potentially, if you could evaluate that, no diversity 22 is required. But yet what do we do? Even though we 23 fill that type of independence into it, one of the 24 many independences, you still have the probability of 25 something.
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178 1 Maybe you have it and we do something 2 else. We put diversity into it. Just somewhere we 3 got to move past this part of the slides. I'm not 4 quite sure what to do with this, but we've got to move 5 on. Okay. Next slide, 28.
6 (Simultaneous speaking.)
7 MEMBER BROWN: Excuse me for interrupting, 8 Norbert.
9 MR. CARTE: Michael, slide 27. Thank you.
10 MR. DARBALI: So now we're going to 11 discuss the changes made in Section B.4 regarding 12 (audio interference). So like you see in the first 13 column of the table, it's a summary of the six 14 acceptance criteria from Section B.4 and their 15 applicability based on how 0.4 is addressed.
16 So going back to 0.4, 0.4 requires that 17 independent and diverse main control room displays and 18 controls be provided for manual system level actuation 19 of risk informed critical safety functions. All of 20 the six acceptance criteria are applicable as shown in 21 the second column titled 0.4 approach. And these are 22 the six acceptance criteria that you can find in 23 Division 8 of the BTP.
24 So when you've seen the first two columns, 25 it's basically Revision 8. As we noted earlier, the 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
179 1 SRN added a sentence at the end that says that an 2 applicant may alternately propose a different approach 3 to the requirements in 0.4 if the plan has the 4 commensurate level of safety. So what we did in the 5 BTP as identified in the last column to the right 6 titled different approach is we identified which of 7 the existing six acceptance criteria would apply to a 8 different proposed approach.
9 So as you can see in the last column, we 10 determined that the acceptance criteria items A, C, E 11 and F would still apply to a proposed approach. But 12 when it comes to the acceptance criteria items Bravo 13 and Delta, the reviewer should determine that the 14 application contains appropriate certification based 15 on the commensurate level of safety in the planned 16 site. Next slide.
17 So we recognize that now we've added all 18 this new guidance for reviewing the risk informed 3D 19 assessment. It can be a bit more confusing to figure 20 out how to use the BTP and identify what sections 21 apply and when. So we've added four flow charts.
22 Each one is centered around each of the four points.
23 And this should help the reviewers understand what are 24 the conceptual steps in performing the review and 25 identify which sections of the BTP contained the 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
180 1 guidance for performing that review. Next slide.
2 And finally, to address a prior comment 3 made to the ACRS, we've added language from Regulatory 4 Guide 1.152 regarding communication independence and 5 control of access to prevent unauthorized access to a 6 safety-related system. And we provided an example 7 indicating that the use of forward base unidirectional 8 communication is an approach that staff consider 9 successful. And this can be done with a hardware base 10 unidirectional device.
11 MEMBER MARCH-LEUBA: Sorry, Charlie. I 12 know we're late. But number one bullet, so you only 13 have to prevent an authorized access if the licensee 14 is nice enough to consider cybersecurity? If they 15 don't consider cybersecurity, they're even more 16 susceptible to it. They can have a path.
17 (Simultaneous speaking.)
18 MR. DARBALI: Right. That's not the 19 intention. The language we use in the BTP is the same 20 language we use in Reg Guide 1.152 which the committee 21 had looked at.
22 MEMBER MARCH-LEUBA: There's a shall in 23 there. The licensee shall ensure there is no 24 unauthorized access.
25 MR. DARBALI: Right.
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181 1 MEMBER MARCH-LEUBA: I mean, it's not in 2 here. There's a should and it's considered only when 3 it's considered --
4 MR. DARBALI: Well, right. And again, we 5 do have control of access guidance in IEEE 7432 as 6 endorsed in Reg Guide 1.152. It does say shall not 7 have --
8 MEMBER MARCH-LEUBA: I place my concern.
9 That's important. And in my opinion, forget about 10 CCF. Forget about all the other PRA results. That is 11 going to cause a problem in the reactor in the next 12 ten years. That should be considered. Unauthorized 13 access by a bad actor is the most likely -- if you 14 risk -- and everybody just laughs when I say it.
15 (Simultaneous speaking.)
16 MEMBER MARCH-LEUBA: No, you're not.
17 MR. DARBALI: We agree. Our position is 18 that the regulatory guides that include these 19 requirements as well as the cybersecurity program.
20 CHAIRMAN REMPE: You make it real short.
21 You want them to say measurers shall be included or 22 must be included instead of should is the comment 23 you're trying to make.
24 MEMBER MARCH-LEUBA: Only if they're nice 25 enough to consider cybersecurity.
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182 1 CHAIRMAN REMPE: (Audio interference) Reg 2 Guide. But anyway, go ahead.
3 MR. CARTE: Norbert Carte, we to look at 4 those words a little better. But the basic idea is we 5 would prefer to have no difficult communication into 6 a safety system and have the safety system as simple 7 as possible. And if that is the case, then you don't 8 need cybersecurity to actually control measures in the 9 protection system, right?
10 MEMBER MARCH-LEUBA: I better disagree.
11 MR. CARTE: But that's the concept.
12 (Simultaneous speaking.)
13 MEMBER MARCH-LEUBA: The trend is to have 14 micro-reactors that are parachute dropped into Alaska 15 and controlled from Chicago. That's the trend. And 16 second, I will email you a link of an Israeli research 17 paper in which they hijacked a camera in the corner of 18 the room and pointed it to the LEV on the computer --
19 the power LEV of the computer.
20 And just by looking at that were able to 21 get the draft keys they were using for the HDPS. So 22 the fact that you don't have a cable doesn't mean they 23 can't get it. But keep going.
24 MR. CARTE: That's the concept behind that 25 statement.
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183 1 DR. BLEY: Before you keep going, this is 2 Dennis. I just searched the document for these words.
3 I don't think the slide has the same words that's in 4 the Reg Guide. If they do, I agree with Jose. But 5 I'm not sure they're in there anywhere.
6 MR. DARBALI: If you go to Section 2 7 titled Relevant Guidance, we have an item there for 8 Reg Guide 1.152.
9 MEMBER BROWN: On page 8?
10 DR. BLEY: And it has these same words.
11 Okay.
12 MEMBER BROWN: I had a little bit of 13 difficulty with that just being in the Reg Guide.
14 That's the only place the word cyber is used I 15 remember. So the idea of cyber and the basic defense 16 in depth functionality of the document is not listed.
17 It's only a related -- what do you call this section?
18 I forgot --
19 (Simultaneous speaking.)
20 MR. DARBALI: Relevant guidance.
21 MEMBER BROWN: Relevant guidance. So 22 that's not really part of the fundamental defense in 23 depth evaluation where cyber really if they're going 24 to consider it, it ought to be considered as part of 25 the defense in depth design of the system regardless 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
184 1 of how it comes out, whether you like it if it's done 2 the way I do or not. But somebody has to look at 3 that.
4 And I agree. I understand Norbert's point 5 and that if you have no communications, there's no 6 lines. But if you look at all the RPS systems we've 7 looked at, plant data comes out of that system. It 8 goes to the main control room.
9 That should be (audio interference). But 10 it's only addressed through this part of the (audio 11 interference). So it made cyber really have a defense 12 in depth issue associated with it. And it's really 13 not covered explicitly other than it's related 14 guidance.
15 And I think (audio interference) should be 16 incorporated as part of the -- and I don't know which 17 section it goes in. But it's in the diversity 18 section, not at the risk informed section. So I mean, 19 if you want to risk inform it, you can say 20 cybersecurity is a piece of cake because everybody 21 knows we've got wonderful software that will protect 22 it forever. And if you an figure that one out, then 23 I don't what your system. But that's another point.
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185 1 section, completely separate from a risk informed 2 (audio interference).
3 MEMBER BROWN: I know. Okay. Although we 4 could argue if you're doing a risk informed analysis, 5 why don't you have similar words that if cyber is 6 being evaluated via the design. I don't know why we 7 say if it's being considered. But I know all of the 8 political kerfuffle that we have to go through this to 9 get to this point.
10 MR. DARBALI: Right.
11 DR. BLEY: If you think where Jose 12 started, if you just get rid of that first phrase, if 13 licensees and applications consider the cybersecurity 14 design features, delete that. Measures should be 15 included. That's the point, I believe.
16 MEMBER BROWN: Yes, but it ought to be --
17 (Simultaneous speaking.)
18 DR. BLEY: If you don't do cyber and don't 19 do this, it's worse than just (audio interference).
20 MEMBER BROWN: No, I agree with you. But 21 we've fought that battle trying to get words into --
22 it was a battle just getting considered into 1.152 as 23 opposed to --
24 DR. BLEY: Yeah, but that was a little 25 different. But okay.
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186 1 CHAIRMAN REMPE: But I agree with what 2 Dennis is saying because there's context by the prior 3 sentence. And then I might say measures must be 4 included instead of should. But that's all up to you 5 guys.
6 MEMBER BROWN: Yeah, we can't tell you 7 what to do. The addressing of the cyber issue ought 8 to be both under the first (audio interference), the 9 best estimate sections, 1 up to 3.4. And then it 10 ought to be covered independently under the risk 11 informed. But I mean, it's applicable to both, 12 although to me cyber ought to be separate. It 13 shouldn't be under risk informed at all.
14 MEMBER MARCH-LEUBA: Yeah. And well, 15 since you took time, let me put my 20 seconds to the 16 always, my marketing, when you get home, google Casino 17 Aquarium cyber. And you will get -- you probably 18 already know it. So that somebody can rob a casino.
19 I get into the aquarium in the lounge.
20 The bad guys are not going attack the 21 protection system. They're going to attack the 22 aquarium. So when you do cyber, you need to be 23 looking at the aquarium, not the protection system.
24 CHAIRMAN REMPE: How many aquariums?
25 (Simultaneous speaking.)
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187 1 MEMBER BROWN: This part obviously needs 2 to be (audio interference).
3 MR. DARBALI: So just the next steps for 4 completing the draft, so we're looking to (audio 5 interference) public for public commenting in October.
6 Hoping to close the public comment period in November.
7 And this will keep us on track to the final Revision 8 9 in (audio interference).
9 CHAIRMAN REMPE: So although I know Member 10 Brown said something about we're not planning to have 11 you come back. But if things were to change, I assume 12 we'll have adequate time. Sometimes these things will 13 come to us without adequate time to schedule a 14 subcommittee meeting and a full committee meeting.
15 And there's been a lot of comments today. And please, 16 please give us adequate time. Then I won't be 17 chairman by that time. Go ahead.
18 MEMBER BROWN: Thanks. Tom, did you want 19 to read your other questions (audio interference)?
20 MEMBER ROBERTS: My major comments are 21 covered. I think I probably summarized them by having 22 a better alignment between either Reg Guide 1.174 or 23 the appropriate risk informed standard. And through 24 here I think a couple of examples we talked about are 25 the definition of not risk significant doesn't include 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
188 1 the core principles that aren't risk calculation.
2 So that's one aspect. The other aspect is 3 the cases where you are risk significant. It seems 4 like there's really no change from the existing 5 practice. You can use 1.3 and just going ahead and 6 make your case.
7 So it's really up to you whether that's 8 very risk informed by that whole section. It doesn't 9 hold a lot of value. But it may be that when you go 10 try and use it with industry, you might get somebody 11 who uses the risk information. So I guess I would 12 have a major objection to it.
13 It just seems like the way it fits 14 together, it's either not risk significant for Reg 15 Guide 1.174 or there's no real change to the way it's 16 being treated. But let's see. What else? Charlie, 17 do you want to go through the more minor comments, or 18 --
19 MEMBER BROWN: Yeah, I was going to get --
20 I had Reg Guide 1.233 was only in the references 21 section, not in the related guidance. You deleted the 22 ISGO 4 (audio interference). But it's not obvious of 23 why he did that. I mean, that --
24 MR. CARTE: The prioritization information 25 from Reg Guide 1.152 supersedes --
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189 1 MEMBER BROWN: It did supersede? Okay.
2 So that was incorporated?
3 MR. CARTE: That's why we took (audio 4 interference).
5 MEMBER BROWN: That's fine (audio 6 interference).
7 MR. CARTE: Right, you see that's (audio 8 interference).
9 MEMBER BROWN: That's all taken out.
10 MR. CARTE: (Audio interference).
11 MEMBER BROWN: Yeah, but I didn't say one 12 superseded the other. That next one was B.1, Item 13 2.1A. You talked about highly safety significance, 14 safety-related SSCs that perform safety significant 15 functions. The last sentence says -- this is early in 16 the document -- for SSCs in this category, GDC 22 17 requires functional diversity to the extent practical 18 and (audio interference).
19 And the GDC is fairly clear if you go back 20 for all applications of (audio interference) generally 21 in their licensing basis. So I don't see how we can 22 really override that in this particular guidance. And 23 functional diversity is part of the overall diversity 24 evaluation.
25 MR. CARTE: Right. So what we're doing is 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
190 1 we're defining categories. And how the category is 2 treated is not necessarily --
3 MEMBER BROWN: We don't have to resolve 4 this right now.
5 MR. CARTE: But that was our reasoning.
6 MEMBER BROWN: Okay. Just we may need a 7 little bit more discussion, and I want to get on with 8 it. Oh, yeah. You (audio interference) the risk 9 informed D3 assessment (audio interference) NUREG 2122 10 (audio interference). And I couldn't find that 11 regulatory basis (audio interference). Maybe I read 12 too fast. I don't remember seeing that one.
13 We've had enough discussions (audio 14 interference) paragraph 3 (audio interference) should 15 evaluate Digital I&C system interconnectivity. And by 16 the time you walked your way through, it almost leads 17 you to the point where you can have some if you 18 evaluate it property when in reality (audio 19 interference) the interconnectivity (audio 20 interference).
21 That seemed to leave an opening for people 22 to start connecting (audio interference) really 23 evaluating what the (audio interference) paragraph 3 24 of B.3.4.2. That (audio interference) modeling (audio 25 interference). Under manuals B.4, this is back in the 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
191 1 diversity (audio interference).
2 Paragraph 2 stated, for example, the point 3 at which the (audio interference) downstream of the 4 equipment. That could be adversely affected by (audio 5 interference). But it's not included in A.3.2.2 under 6 the diversity (audio interference).
7 So downstream, manual operations should 8 not (audio interference). After that, the rest of the 9 comments were Tom's. If he wants to -- and I'll give 10 you a copy of this (audio interference). Tom, do you 11 have anything else or are you happy?
12 MEMBER ROBERTS: More minor comments. Did 13 you give them a copy of this?
14 MEMBER BROWN: I'll just give them a copy 15 of this.
16 (Simultaneous speaking.)
17 MEMBER ROBERTS: The one that might be 18 worth mentioning is we went through the effort to 19 define what risk significant means in the risk 20 section. It was in the context of comparing to safety 21 significant. But the argument seems to stop halfway 22 through.
23 It doesn't define safety significant and 24 why you talk about risk significant. I'm trying to 25 find that right now. It's in the definition section.
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192 1 It might've been the NUREG that Charlie referenced.
2 MEMBER DIMITRIJEVIC: I notice that too.
3 And that was one of my comments too, Tom. I think the 4 discussion of the risk where the safety should be 5 removed from that because it's not really, like, a PRA 6 in Europe is called PSA, probabilistic safety 7 assessment. I think that's a philosophical discussion 8 and it shouldn't be in this.
9 MEMBER ROBERTS: So that's for your 10 consideration, deleting it or finishing it. I would 11 suggest one or the other. Just to know where I am, it 12 says, risk significance and safety significance are 13 different concepts. And it says NUREG 2122 defines 14 risk as and then it stops talking.
15 And so it started an argument it didn't 16 finish. So it's not to suggest that just deleting the 17 start of the argument (audio interference), or if you 18 had a reason for putting that in there, then finish 19 the argument.
20 MEMBER BROWN: He explains that (audio 21 interference).
22 MEMBER ROBERTS: I called the rest of mine 23 editorial (audio interference).
24 CHAIRMAN REMPE: There's one thing I'm 25 worried about backup. And I went and talked to Larry.
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193 1 Are either of you opposed -- if you're going to be 2 passing this to staff, the public meeting that it get 3 added to the official record and just kind of title on 4 there saying Member Roberts or Member Brown comments 5 and stuff and we can be added?
6 MEMBER BROWN: Yeah, that's fine.
7 CHAIRMAN REMPE: Just wanted to make sure 8 we discuss that here in the open. Because if there's 9 a document going --
10 (Simultaneous speaking.)
11 MEMBER BROWN: No, I totally understand.
12 I just copied the last part.
13 (Simultaneous speaking.)
14 CHAIRMAN REMPE: Yeah, this is a little 15 different than normal. But I've done it. I've seen 16 it done in subcommittee.
17 MEMBER BROWN: You're trying to get (audio 18 interference) make sure we stay within the rules.
19 (Audio interference) public comment now. Is there 20 anybody on the lines that we're going to make a 21 comment? Not hearing any --
22 MEMBER MARCH-LEUBA: No, I want to say I 23 hear Charlie asking for public comments.
24 MEMBER BROWN: You did hear me? Okay.
25 Are there any other member comments without getting 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
194 1 back into the PRA business and spending the next half 2 an hour (audio interference)? I don't see -- oh, 3 Walt. Okay.
4 MEMBER KIRCHNER: Yes, this may seem odd 5 coming from me. But I think the idea has been formed 6 decision making (audio interference).
7 MEMBER MARCH-LEUBA: Walt, speak up.
8 MEMBER KIRCHNER: Okay. I think today 9 when we were talking about risk informed decision 10 making, the context (audio interference). We kicked 11 around some examples. I would submit that the risk 12 informed decision making takes the PRA in the broader 13 context of the NRC's regulatory (audio interference).
14 So I would submit that some of the 15 rhetorical examples that we kicked around today would 16 be a very heavy lift for (audio interference) that 17 they wouldn't have an independent means to scram the 18 reactor. I would just (audio interference) Criteria 19 27. So it's just not --
20 MEMBER BROWN: What you mean is it would 21 be difficult to apply a risk informed approach.
22 MEMBER KIRCHNER: No, I think the risk 23 informed would help you explore the vulnerabilities of 24 the system.
25 (Simultaneous speaking.)
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195 1 MEMBER KIRCHNER: -- regulatory, like, 2 action, it's a system in its entirety acceptable.
3 It's not just the delta PRA results. It's in the 4 context of regulatory framework. And there are other 5 considerations.
6 I just felt that the tenor of the 7 discussion about risk informed decision making came in 8 for some hard knocks today. But it's not just the 9 delta CDFs and LERFs and such that the staff would use 10 when they made the decision (audio interference) or 11 reactor application. I'll stop there.
12 MEMBER BROWN: No, I agree with you. I 13 think there's a way -- we're going to have the ability 14 to be risk informing somehow within the defense in 15 depth (audio interference). You got to start with 16 something.
17 I may not like everything that's in there.
18 But while I think (audio interference) PRA, the risk 19 informed process -- thought process of looking at 20 whether I need or don't need certain things or some 21 diversity or not gets applied. I just have a hard 22 spot relative to trying to put numbers and CDFs and 23 deltas in little boxes. I think there's a way to use 24 it in a more qualitative manner which gives you a feel 25 for I can go this way or not.
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196 1 I don't know (audio interference) or 2 whether there will be subsequent revisions. But the 3 Commission has asked for it, and I think we need to 4 try to get it (audio interference) as we can. It's 5 not for us to tell them no. No more. That's it.
6 CHAIRMAN REMPE: Okay. So at this point, 7 I'm going to tell the court reporter we're going off 8 the record.
9 (Whereupon, the above-entitled matter went 10 off the record at 3:17 p.m.)
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ATTACHMENT - Member Charles Brown and Member Thomas Roberts Comments on Inconsistencies of Proposed Rev.9 to BTP 7-19 (ML23222A237), their review presented at the end of the Full Committee Meeting, September 7, 2023 (Item 9 of the Agenda)
- 1. Section A.1 Regulatory Basis
- a. RG 1.233 is not included in this section even though it is referenced in the SRM and in the text.
- 2. Section B.1 Safety-Significance Determination
- a. Item 2.1.a. high safety significance: safety-related SSCs that perform safety-significant functions - The last sentence For SSCs in this category, GDC 22 requires functional diversity, to the extent practical. has been deleted. Why?
- 3. Section B.3.4 Risk-Informed D3 Assessment- A quote from NUREG-2122 is called out as a principal focus for determining risk significance, but NUREG-2122 is not listed in the Regulatory Basis section.
- 4. Section B.3.4.2 Modeling the CCF
- a. Paragraph 1 - Modeling of hardware or software components.
One limitation is that some PRA models do not include details of various hardware or software components of DI&C systems or all the interdependencies across different SSCs.
Comment - Modeling of software based digital systems is extremely difficult if not impossible with any confidence. Is this likely to dampen licensee willingness to adopt a risk informed process to negate the need for diversity?
- b. Paragraph 3 - In providing the justification, the application should evaluate DI&C system interconnectivity and address DI&C system spatial separation that could significantly influence the risk due to fires, earthquakes, and other hazards. This can be accomplished through detailed modeling of the DI&C system in the PRA or the use of surrogate events, which can be existing basic events in the PRA or new basic events added to the PRA that capture the impact of the CCF on the plant.
Comment - The interconnectivity within RPS reactor trip system divisions and within ESFAS trip system divisions should be ZERO with the exception of final voting modules. The statement in this paragraph leads one to believe that routine interconnections between divisions and systems are acceptable under some circumstances not identified.
- 5. Section B.4 - Manual System-Level Actuation and Indications to Address Point 4
- a. Paragraph 2 - The sentence For example, the point at which the credited manual controls are connected to the safety equipment should be downstream of the equipment that can be adversely affected by a CCF. is addressed here when addressing Point 4 but not similarly under Section B.3.2.2 Crediting Manual Operator Action as a diverse means when addressing Point 3.
- 6. It is not clear how the risk-informed acceptance criteria are consistent with other risk-informed methods such as RG 1.174. It is suggested the alignment with other such methods be explained or improved. Examples include:
- a. RG 1.174 lists five principles that must be addressed: (1) is the change consistent with regulation; (2) does the change affect defense-in-depth; (3) does the change affect safety margins; (4) are changes in risk small; and (5) performance metrics should be employed to monitor change. The discussion in section B3.4.3 (Determining the Risk Significance of the CCF) of the draft BTP 7-19 revision addresses only item (4) from this list under the sub-heading For CCFs determined to be not risk significant. There is an earlier reference in the section to defense-in-depth, but it applies only for cases where CCF likelihood was assumed to be less than 1.0; it is not clear why this would not always apply. No other discussion of principles (1), (3), or (5) from the above RG 1.174-derived list is included in the BTP 7-19 revision.
- b. Section B 3.4.3 of the BTP revision clearly states acceptance limits that would require the increase in risk to fall within Region III from Figures 4 and 5 of RG 1.174. However, section B 3.4.4 allows for larger changes in risk that would fall within Regions I or II of the RG 1.174 figures. No explanation is provided on why such a higher risk would be acceptable for a risk-informed evaluation using the guidance of BTP 7-19. for example, the following RG 1.174 statement is not addressed: Applications that result in increases to CDF above 10-5 per reactor year (i.e., the increase in CDF falls within Region I of Figure 4) would not normally be considered. The draft BTP sends the reader to section B 3.1.3 for further clarification, but this section (Use of Alternative Approaches Other Than Diversity and Testing to Eliminate the Potential for Common-Cause Failure
from Further Consideration) applies to deterministic evaluations of CCFs and how it applies to risk-informed evaluations is not clear.
- c. Section B.1.1, in its quoting of the revised Commission-approved principles, lists both RG 1.174 and 1.233 as providing risk-informed principles. While the BTP revision addresses consistency with RG 1.174, it does not explain why the Commission policy statement cited RG 1.233. Instead, it provides a reference to SRP section 19.0. It is suggested that the reason for also citing RG 1.233 in the Commission-approved principle be explained, including how it either differs from or adds to the RG 1.174 reference.
- 7. The differences between the existing deterministic methods in section B 3.1 through B.3.3 and the risk-informed methods in section B 3.4 are not clear in all cases and further clarification is suggested. Section B.3.4 makes a point that safety-significant and risk-significant are different concepts, and then provides a definition of risk-significant. No similar definition of safety-significant is provided in the section, nor does the section explain why the difference between these terms is important to the BTP. The intended point might have been to explain why the deterministic methods of B 3.1 through B 3.3 cannot be mixed with the risk-informed methods of B 3.4, but this point is not made in the text. It is suggested that this discussion be completed.
- 8. The following comments are editorial or questions regarding proposed word changes:
- a. Front matter, background: Latent design defects are errors in the design of the DI&C system or component that can remain undetected
despite rigorous design-basis development, verification, validation, and testing processes. It is not clear why this change was made.
The deleted phrase at the end of the sentence explains how hard it is to preclude CCFs in a DI&C system, and deleting that phrase removes information that would appear to be useful for a first-time reader of the BTP. It is suggested this phrase be restored or its deletion justified.
This comment applies also to Section B 3.1.2, where the following sentence is being deleted: However, even a high-quality development process cannot completely eliminate latent design defects introduced during the design and integration process.
- b. Section B 2.1, System Interconnectivity Discussion - After revision, includes a sentence which states, If the reactor trip or engineered safety feature (ESF) initiation signal in such a system reaches the final actuation device only through the equipment that performs control functions, then the reviewer should determine whether all the SSCs in that pathway have been assigned to the highest safety significant SSC category. GDC 24 requires separation of protection and control functions, such that this sentence appears to describe a system architecture that would not be permitted per GDC-
- 24. Prior to deletions made to this paragraph, it was clear that the term control functions in this sentence did not refer to the plant control system, but after deletions its not as clear. Clarification is suggested.
- c. Section B 3.1.1 - This section ends with a Revision 8 example, which the proposed revision 9 deletes. For example, a proposed digital protection system could implement each credited safety function in two or more independent divisions of the system, each using a different type of digital technology. In this case, the reviewer should determine whether the application includes an analysis reflecting the guidance of NUREG/CR-6303 and NUREG/CR-7007 to demonstrate that the diversity of these independent divisions is sufficient to eliminate a CCF from further consideration.
It is not clear why this example is being deleted. It not only can be helpful to the first-time reader of this document but sets a basis for a satisfactory design and is currently used in installed approved replacement DI&C applications.
Clarification is suggested.
SRM-SECY-22-0076 Implementation:
Branch Technical Position 7-19, Draft Revision 9 Advisory Committee on Reactor Safeguards Digital Instrumentation & Controls Briefing September 7, 2023
Opening Remarks Presentation Outline
- Background
- SRM-SECY-93-087 and SRM-SECY-22-0076 Points
- SRM-SECY-22-0076 Direction and Staff Proposed Response
- Substantive Changes to BTP 7-19
- Next Steps
- Closing Remarks 3
SRM-SECY-93-087 Point 1 The applicant shall assess the defense-in-depth and diversity of the proposed instrumentation and control system to demonstrate that vulnerabilities to common-mode failures have adequately been addressed.
4
SRM-SECY-93-087 Point 2 In performing the assessment, the vendor or applicant shall analyze each postulated common-mode failure for each event that is evaluated in the accident analysis section of the safety analysis report (SAR) using best-estimate methods. The vendor or applicant shall demonstrate adequate diversity within the design for each of these events.
5
SRM-SECY-93-087 Point 3 If a postulated common-mode failure could disable a safety function, then a diverse means, with a documented basis that the diverse means is unlikely to be subject to the same common-mode failure, shall be required to perform either the same function or a different function. The diverse or different function may be performed by a non-safety system if the system is of sufficient quality to perform the necessary function under the associated event conditions.
6
SRM-SECY-93-087 Point 4 A set of safety grade displays and controls located in the main control room shall be provided for manual, system-level actuation of critical safety functions and monitoring of parameters that support the safety functions.
The displays and controls shall be independent and diverse from the safety computer system identified in items 1 and 3 above.
7
SRM-SECY-22-0076 Point 1 The applicant shall must assess the defense in depth and diversity of the facility incorporating the proposed digital I&C system to demonstrate that vulnerabilities to digital CCFs have been adequately identified and addressed.
The defense-in-depth and diversity assessment shall must be commensurate with the risk significance of the proposed digital I&C system.
8
SRM-SECY-22-0076 Point 2 In performing the defense-in-depth and diversity assessment, the applicant shall must analyze each postulated CCF. This assessment may use using either best-estimate methods or a risk-informed approach or both.
When using best-estimate methods, the applicant shall must demonstrate adequate defense in depth and diversity within the facilitys design for each event evaluated in the accident analysis section of the safety analysis report.
9
SRM-SECY-22-0076 Point 2 (Continued)
When using a risk-informed approach, the applicant shall must include an evaluation of the approach against the Commissions policy and guidance, including any applicable regulations, for risk-informed decision-making.
The NRC staff will review applications that use risk-informed approaches for consistency with established NRC policy and guidance on risk-informed decision-making (e.g., Regulatory Guide (RG) 1.174, An Approach for Using Probabilistic Risk Assessment in Risk-Informed Decisions on Plant-Specific Changes to the Licensing Basis, RG 1.233, Guidance for a Technology-inclusive, Risk-informed, and Performance-based Methodology to Inform the Licensing Basis and Content of Applications for Licenses, Certifications, and Approvals for Non-Light-Water Reactors).
10
SRM-SECY-22-0076 Point 3 The defense-in-depth and diversity assessment may must demonstrate that a postulated CCF can be reasonably prevented or mitigated or is not risk significant. The applicant shall must demonstrate the adequacy of any design techniques, prevention measures, or mitigation measures, other than diversity, that are credited in the assessment. The level of technical justification demonstrating the adequacy of these techniques or measures, other than diversity, to address potential CCFs shall must be commensurate with the risk significance of each postulated CCF.
11
SRM-SECY-22-0076 Point 3 (Continued)
A diverse means that performs either the same function or a different function is acceptable to address a postulated CCF, provided that the assessment includes a documented basis showing that the diverse means is unlikely to be subject to the same CCF. The diverse means may be performed by a system that is not safety-related if the system is of sufficient quality to reliably perform the necessary function under the associated event conditions. Either automatic or manual actuation within an acceptable timeframe is an acceptable means of diverse actuation.
12
SRM-SECY-22-0076 Point 3 (Continued)
If a postulated CCF is risk significant and the assessment does not demonstrate the adequacy of other design techniques, prevention measures, or mitigation measures, then a diverse means shall must be provided.
13
SRM-SECY-22-0076 Point 4 Main control room displays and controls that are independent and diverse from the proposed digital I&C system (i.e., unlikely to be subject to the same CCF) shall must be provided for manual, system-level actuation of risk-informed critical safety functions and monitoring of parameters that support the safety functions. These main control room displays and controls may be used to address point 3, above. The applicant may alternatively propose a different approach to this point in the policy if the plant design has a commensurate level of safety.
14
SRM-SECY-22-0076
- The Commission approved the staffs recommendation to expand the existing policy for digital I&C CCFs to allow the use of risk-informed approaches to demonstrate the appropriate level of defense-in-depth, subject to the edits provided
- The staff should clarify in the implementing guidance that the new policy is independent of the licensing pathway selected by reactor licensees and applicants
- The staff should complete the final implementing guidance within a year from the date of the SRM 15
Staff Proposed Response to Meet the SRM Drafted Rev. 9 to SRP BTP 7-19
- Allows the staff to review risk-informed applications
- May result in use of design techniques other than diversity
- Focused the edits on the expanded policy 16
Substantive Changes to BTP 7-19
- Revised Section B.1.1 to reflect the updated four points in SRM-SECY-22-0076
- Revised Section B.1.2 for clarification of critical safety functions
- Added Section B.3.4 for evaluation of risk-informed D3 assessment
- Revised Section B.3.1.3 to support Section B.3.4 for evaluation of alternative approaches
- Revised Section B.4 for evaluation of different approaches for meeting Point 4
- Added four flowcharts to facilitate the review
- Added language from RG 1.152 to address a prior commitment to ACRS regarding communication independence and control of access 17
Updated Four Points of the Policy (Section B.1.1)
- Replaced the four SRM-SECY-93-087 points with the SRM-SECY-22-0076 points
- Updated the explanation of the four points to reflect the language in the SRM-SECY-22-0076 points
- Identified the applicable BTP sections for the evaluation of an application against these four points 18
Critical Safety Functions (Section B.1.2)
- Clarified that critical safety functions are those most important safety functions to be accomplished or maintained to prevent a direct and immediate threat to the health and safety of the public
- Clarified that the critical safety functions identified in SECY-93-087 are examples representative of operating light water reactors
- Clarified that other types of reactors may have different critical safety functions based on the reactor design safety analysis
- the identification of such functions may be risk-informed 19
Risk-Informed D3 Assessment Process Address the CCF using a Address the CCF risk-informed approach deterministically Determine consistency with NRC policy and guidance on RIDM (Section B.3.4.1)
Model the CCF in the PRA Identify each (Section B.3.4.2) postulated CCF Determine the risk significance of the CCF (Section B.3.4.3)
Determine appropriate means to address the CCF (Section B.3.4.4)
Justify alternative approaches 20
Risk-Informed D3 Assessment (Section B.3.4.1)
Determine Consistency with NRC Policy and Guidance on RIDM
- Review applications that use risk-informed approaches for consistency with established NRC policy and guidance on RIDM
- Current staff review guidance includes:
- SRP Chapter 19
- SRP Chapter 19 provides review guidance for addressing the principles of risk-informed decision-making, including defense in depth 21
Risk-Informed D3 Assessment (Section B.3.4.2)
- Evaluate how the CCF is modeled in the PRA and the justification that the modeling adequately captures the impact of the CCF on the plant
- Detailed modeling of the DI&C system
- Use of surrogate events 22
Risk-Informed D3 Assessment (Section B.3.4.3)
Determine the Risk Significance of the CCF
- The risk significance of a CCF can be determined using a bounding sensitivity analysis or a conservative sensitivity analysis
- A bounding sensitivity analysis:
- Assumes the CCF occurs
- Provides a description of the baseline risk
- A conservative sensitivity analysis:
- Provides a technical basis for a conservative probability (less than 1) of the CCF demonstrating that defense in depth is addressed
- Addresses the impact of this assumption on PRA uncertainty 23
Risk-Informed D3 Assessment (Section B.3.4.3)
Determine the Risk Significance of the CCF
- The quantification accounts for any dependencies introduced by the CCF, including the ability for operators to perform manual actions
- A CCF is not risk significant if the following criteria are met for the sensitivity analysis:
- The increase in CDF is less than 1 x 10-6 per year
- The increase in LERF is less than 1 x 10-7 per year 24
Risk-Informed D3 Assessment (Section B.3.4.4) 25
Alternatives to Diversity (Section B.3.1.3)
Two Pathways
- Previous endorsement (e.g., RG) or approval (e.g., precedent or Topical Report)
- Ensure it is applicable
- Ensure it is followed
- Justify any deviations
- A new approach proposed as part of an application
- Use the acceptance criteria in BTP 7-19
- Review description of vulnerability being addressed
- Review description of alternative approach and justification (commensurate with the risk significance of the CCF per Section B.3.4.4) 26
Different Approaches for Meeting Point 4 Point 4 Different Summary of Acceptance Criteria in Section B.4 Approach Approach
- a. Proposed manual actions credited are both feasible and reliable, as Applies demonstrated through an HFE analysis and assessment process
- b. Application identifies the minimum inventory of displays and controls in the MCR that allows the operator to effectively initiate, monitor and control the Applies If justified*
critical safety function parameters
- c. Manual operator actions are prescribed by procedures and subject to training Applies
- d. Manual controls are at the system or division level and located within the MCR Applies If justified*
- e. Quality and reliability of any equipment that is not safety-related is adequate Applies
- f. Displays and controls are independent and diverse (not affected by the same postulated CCFs that could disable the corresponding functions within the Applies proposed DI&C systems)
- The application contains appropriate justification based on the commensurate level of safety in the plant design to ensure operators ability to monitor, initiate and control the applicable critical safety function parameters is maintained.
27
Flowcharts to Facilitate the Use of the BTP
- Added four flowcharts at the end of the BTP:
- Figure 7-19-1. Point 1 - Need for a Detailed D3 Assessment
- Figure 7-19-2. Point 2 - Detailed Assessment
- Figure 7-19-3. Point 3 - Addressing, Mitigating or Accepting the Consequences of Each CCF
- Figure 7-19-4. Point 4 - Independent and Diverse Displays and Manual Controls
- The flowcharts provide a visual aid to the reviewers when reviewing an application against the four points
- identify the conceptual steps for performing the review
- identify the applicable BTP sections 28
Communication Independence Added language from RG 1.152 to address a prior commitment to the ACRS concerning inclusion of communication independence and control of access
- Added a statement that, if licensees and applicants consider the cybersecurity design features, measures should be included to ensure that safety-related I&C systems do not present an electronic path that could enable unauthorized access to the plants safety-related system
- e.g., the use of a hardware-based unidirectional device is one approach the NRC staff would consider acceptable for implementing such measures 29
Next Steps
- The staff is planning to issue the draft BTP 7-19, Rev. 9 for public comment in October 2023
- The public comment period is expected to end in November 2023
- The staff is planning to issue the final BTP 7-19, Rev. 9 in May 2024 30
Closing Remarks Acronyms ACRS Advisory Committee on Reactor Safeguards LERF Large Early Release Frequency BTP Branch Technical Position LMP Licensing Modernization Project CCF Common Cause Failure LWR Light-Water Reactor CDF Core Damage Frequency NEI Nuclear Energy Institute D3 Defense-in-Depth and Diversity NRC Nuclear Regulatory Commission DAS Diverse Actuation System PRA Probabilistic Risk Assessment DI&C Digital Instrumentation and Control RG Regulatory Guide DRG Design Review Guide RIDM Risk-Informed Decision-Making ESFAS Engineered Safety Features Actuation System RPS Reactor Protection System GDC General Design Criteria SECY Commission Paper I&C Instrumentation and Control SRM Staff Requirements Memorandum ISG Interim Staff Guidance SRP Standard Review Plan
NRC Reviews of Volcanic Hazards Assessments for New Reactor Licensing September 7, 2023 Jenise Thompson NRR/DEX/EXHB 1
Where were at and where were going Completed Actions Upcoming Activities
- Issued Regulatory Guide 4.26
- TerraPower Volcanic Hazards topical
- CFPP and TerraPower permit/license
- Observers to INL volcanic hazards applications assessment
Regulatory Requirements
- 10 CFR Part 50, Appendix A, General Design Criteria for Nuclear Power Plants, General Design Criterion 2
- 10 CFR 52.17(a)(1)(vi) for an early site permit and 10 CFR 52.79(a)(1)(iii) for a combined license
- 10 CFR 100.23, Reactor Site Criteria 3
Regulatory Background
- RG 4.26 Volcanic Hazards Assessment for New Nuclear Power Reactor Sites
- Briefed to ACRS February 2020 and April 2021
- Revision 0 issued June 2021 (ML20272A168)
- Revision 1 administrative change August 2023 (ML23167A078)
- Options to assess volcanic hazard or pursue engineering analysis based on maximum screened-in hazard 4
RG 4.26 - Hazard Analysis
- Multiple off-ramps
- Acceptable (A) results can use the off ramp
- Unacceptable results (U) continue process
- Quaternary Period (<2.6 Ma)
- Site region within 200 mi (320 km) and site vicinity within 25 mi (40 km) 5
RG 4.26 - Engineering Analysis
- Determine maximum magnitude for screened in hazards
- Iterate between evaluating SSC performance and mitigating actions, if desired 6
Reviewing Volcanic Hazards Assessments
- Geologic History
- Site Characterization
- Tectono-magmatic Model
- Numerical Modeling
- Engineering Considerations 7
Ongoing Activities
- Carbon Free Power Project White Paper (ML22224A196)
- Staff assessment completed (ML22279A897)
- Idaho National Laboratory Probabilistic Volcanic Hazards Assessment
- Following Senior Seismic Hazard Analysis Committee (SSHAC) process
- NRC observers at all workshops and field visit
- TerraPower Volcanic Hazards Assessment Topical Report (ML23115A387) 8
Prospective Sites and Regional Volcanic Sources 9
From USGS Yellowstone Volcano Observatory
Eastern Snake River Plain (ESRP) 10 Figure from Gallant et al. 2018
Yellowstone Caldera Deposits
- Lava Creek Tuff ~630,000 years
- Mesa Falls Tuff ~ 1.3 Ma
- Huckleberry Ridge ~ 2.1 Ma From USGS Fact Sheet 2005-3024 11
Yellowstone Caldera
- Constant monitoring
- Seismometer
- Temperature
- GPS
- Gas
- Camera
- Tiltmeter 12 From USGS Yellowstone Volcano Observatory
Volcanic Hazards
- Tephra Fall
- Lava Flow
- New Vent Opening
- Proximal Hazards 13
Tephra (Ash) Hazards
- Can travel long distances
- Wide range in particle size and deposit density
- Hazards to air intakes and switchyards
- Thickness of deposit, potentially affected SSCs and warning time are important to assessing impact of hazard on site 14
Lava Flow
- Dense, hot, with heat capacity comparable to metals
- Distance traveled from source to site will depend on local conditions
- Flow direction generally follows topography 15
New Vent Opening and Proximal Hazards
- Generally preceded by increased seismic activity and surface deformation
- Eruptive dike may not reach the surface but effects will be noticeable 16
Proximal Hazards Ballistics Tension Crack 17
Numerical Modeling
- Several programs available
- TerraPower
- AshPlume - developed through NRC contract to CNWRA to support tephra hazard modeling at Yucca Mountain, models atmospheric dispersion and deposition of tephra
- PVHA_YM - developed through NRC contract with CNWRA to support volcanic hazard modeling at Yucca Mountain, estimates the probability of a volcanic event occurring within an effective area using kernel density estimators
- INL/CFPP
- Tephra2 - open-source code developed by team at University of South Florida, models tephra accumulation at locations around a source volcano
- MOLASSES - open-source code developed by team at University of South Florida, estimates area inundated by lava flows for pre-loaded digital elevation model.
18
Future Licensing Reviews
- Applicants are following RG 4.26 with minor alterations
- Staff preparing for confirmatory calculations of numerical modeling
- Site visits
- Staff already visited INL to observe important features
- Expect to visit TerraPower site as part of licensing review 19
Future Licensing Reviews
- Mitigating Actions and Monitoring
- Criteria for initiation
- Early warning of impending hazard
- Demonstrate practicality of actions between warning and arrival of hazard
- Permit/License Condition(s)
- Geologic mapping permit/license condition 20
What comes next
- Ongoing review of TerraPower Topical Report
- Reviews for CFPP and TerraPower CP/COLs
- Lessons learned from CFPP white paper, TerraPower Topical Report and licensing reviews
- Revise RG 4.26 21