ML20205Q953
| ML20205Q953 | |
| Person / Time | |
|---|---|
| Issue date: | 07/21/2020 |
| From: | Advisory Committee on Reactor Safeguards |
| To: | |
| Snodderly, M, ACRS | |
| References | |
| NRC-0985 | |
| Download: ML20205Q953 (304) | |
Text
Official Transcript of Proceedings NUCLEAR REGULATORY COMMISSION
Title:
Advisory Committee on Reactor Safeguards Open Meeting Docket Number: (n/a)
Location: teleconference Date: Tuesday, July 21, 2020 Work Order No.: NRC-0985 Pages 1-274 NEAL R. GROSS AND CO., INC.
Court Reporters and Transcribers 1323 Rhode Island Avenue, N.W.
Washington, D.C. 20005 (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.
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1 1 UNITED STATES OF AMERICA 2 NUCLEAR REGULATORY COMMISSION 3 + + + + +
4 676TH MEETING 5 ADVISORY COMMITTEE ON REACTOR SAFEGUARDS 6 (ACRS) 7 + + + + +
8 OPEN SESSION 9 + + + + +
10 TUESDAY, JULY 21, 2020 11 + + + + +
12 The Advisory Committee met via Video-13 Teleconference, at 9:30 a.m. EDT, Matthew W. Sunseri, 14 Chairman, presiding.
15 COMMITTEE MEMBERS:
16 MATTHEW W. SUNSERI, Chairman 17 JOY L. REMPE, Vice Chairman 18 WALTER L. KIRCHNER, Member--at-large 19 RONALD G. BALLINGER, Member 20 DENNIS BLEY, Member 21 CHARLES H. BROWN, JR. Member 22 VESNA B. DIMITRIJEVIC, Member 23 JOSE MARCH-LEUBA, Member 24 DAVID A. PETTI, Member 25 PETER RICCARDELLA, Member NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.
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2 1 ACRS CONSULTANT:
2 MICHAEL CORRADINI 3 STEPHEN SCHULTZ 4
5 DESIGNATED FEDERAL OFFICIAL:
6 MICHAEL SNODDERLY 7 CHRISTOPHER BROWN 8 CHRISTIANA LUI 9 QUYNH NGUYEN 10 WEIDONG WANG 11 12 ALSO PRESENT:
13 BRUCE BAVOL, NRR 14 ANNA BRADFORD, NRR 15 PROSANTA CHOWDHURY, NRR 16 MICHAEL DUDEK, NRR 17 MARIELIZ JOHNSON, NRR 18 MICHAEL MELTON, NuScale 19 SCOTT MOORE, Executive Director, ACRS 20 RYAN NOLAN, NRR 21 ZACKARY RAD, NuScale 22 DINESH TANEJA, NRR 23 PETER YARSKY, RES 24 25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.
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3 1 P R O C E E D I N G S 2 (9:31 a.m.)
3 CHAIR SUNSERI: It is 9:31. We will now 4 call the meeting to order.
5 This is the first day of the 676th Meeting 6 of the Advisory Committee on Reactor Safeguards. I'm 7 Matthew Sunseri, the Chair of the ACRS.
8 Members in attendance today, and I'm going 9 to call the roll. Ron Ballinger.
10 MEMBER BALLINGER: Here.
11 CHAIR SUNSERI: Dennis Bley.
12 MEMBER BLEY: Here.
13 CHAIR SUNSERI: Charles Brown.
14 MEMBER BROWN: Here.
15 CHAIR SUNSERI: Vesna Dimitrijevic.
16 MEMBER DIMITRIJEVIC: Here.
17 CHAIR SUNSERI: Walt Kirchner.
18 MEMBER KIRCHNER: Here.
19 CHAIR SUNSERI: Jose March-Leuba.
20 MEMBER MARCH-LEUBA: Here.
21 CHAIR SUNSERI: Dave Petti.
22 MEMBER PETTI: Here.
23 CHAIR SUNSERI: Joy Rempe.
24 (No response.)
25 CHAIR SUNSERI: And Peter Riccardella.
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4 1 MEMBER RICCARDELLA: I'm here.
2 VICE CHAIR REMPE: Here.
3 CHAIR SUNSERI: And myself.
4 So, we have full attendance and a quorum.
5 The ACRS was established by the Atomic 6 Energy Act. It's governed by the Federal Advisory 7 Committee Act. The ACRS section of the USNRC public 8 website provides information about the history of the 9 ACRS and provides documents such as our charter, 10 bylaws, Federal Register Notices for meetings, letter 11 reports, and transcripts of all full and subcommittee 12 meetings, including all slides presented at the 13 meetings.
14 The committee provides its advice on 15 safety matters to the Commission through its publicly-16 available letter reports.
17 The Federal Register Notice announcing 18 this meeting was published on June 15th, 2020, and 19 provides an agenda and instructions for interested 20 parties to provide written documents or request 21 opportunities to address the committee.
22 The designated federal official for this 23 meeting is Mr. Mike Snodderly.
24 During this week's meeting the committee 25 will take up the NuScale design certification NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.
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5 1 application.
2 Our original agenda had the BWRX-300 topic 3 on here. At the request of the committee, and with 4 concurrence from staff and GE, General Electric-5 Hitachi, we have deferred that presentation until 6 September full committee meeting. That will allow us 7 to give them our full attention when they make their 8 presentation, and it will allow us to give our full 9 attention to NuScale during this set of meetings.
10 So, the progression of this meeting this 11 week will start out with an opportunity for NuScale to 12 provide some comments before we get into any further 13 deliberation today. And that will be followed by 14 staff with follow-up comments.
15 We may go into closed session to protect 16 information designated sensitive or proprietary 17 following that.
18 Once we get through those initial 19 deliberations, then we will begin report preparation,.
20 The transcript will be kept until the 21 point at which we begin our report preparation.
22 A bridge line has been kept -- a bridge 23 line has been opened to allow members of the public to 24 listen in on the presentation and committee 25 discussion. We have received no written comments or NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.
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6 1 requests to make oral statements from the members of 2 the public regarding this week's sessions.
3 There will be an opportunity for public 4 comment, and we have set aside time in the agenda for 5 comments from members of the public who are listening 6 to our meetings. Any written comments may be 7 forwarded to Mr. Mike Snodderly, the designated 8 federal official.
9 Since we are keeping a transcript, it is 10 requested that speakers identify themselves and speak 11 with sufficient clarity and volume so that they can be 12 readily heard.
13 And, as always, since we are conducting 14 this meeting via Skype, we ask that all participants 15 who are not speaking to mute your microphones because 16 it just creates unnecessary distractions with all the 17 background noise that can come across, and it affects 18 the bandwidth of the transmission, which causes 19 sometimes delays in the meeting because of 20 interruption of the signal. So, we appreciate your 21 support of that request.
22 At that time I don't have any other 23 opening remarks. So, I'm going to, I guess, at this 24 point I'm going to -- I'm going to call for a 5-minute 25 recess at this point to allow myself to consult with NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.
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7 1 the executive director before we go forward.
2 So, it's 9:36. We will reconvene at we'll 3 say a quarter till, 9:45 to reconvene.
4 We are recessed. Thank you.
5 (Whereupon, the above-entitled matter went 6 off the record at 9:36 a.m. and resumed at 9:45 a.m.)
7 CHAIR SUNSERI: Okay. This is Matt 8 Sunseri, Chairman of the ACRS. We are going to 9 reconvene. It's 9:45.
10 I will begin once again with a roll call.
11 Ron Ballinger.
12 MEMBER BALLINGER: Here.
13 CHAIR SUNSERI: Dennis Bley.
14 MEMBER BLEY: Here.
15 CHAIR SUNSERI: Charles Brown.
16 MEMBER BROWN: Here.
17 CHAIR SUNSERI: Vesna Dimitrijevic.
18 MEMBER DIMITRIJEVIC: Here.
19 CHAIR SUNSERI: Walt Kirchner.
20 MEMBER KIRCHNER: Here.
21 CHAIR SUNSERI: Jose March-Leuba.
22 MEMBER MARCH-LEUBA: Here.
23 CHAIR SUNSERI: Dave Petti.
24 MEMBER PETTI: Here.
25 CHAIR SUNSERI: Joy Rempe.
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8 1 VICE CHAIR REMPE: Here.
2 CHAIR SUNSERI: Pete Riccardella.
3 MEMBER RICCARDELLA: I'm here.
4 CHAIR SUNSERI: Okay. So, we're all back.
5 And I apologize for that delay. I had some conduct of 6 meeting protocol that I had to discuss with Scott.
7 But we are, we are good to go.
8 And at this point, Walt, do you have 9 anything --
10 MEMBER KIRCHNER: Yes, sir.
11 CHAIR SUNSERI: -- today as chair of the 12 subcommittee?
13 MEMBER KIRCHNER: Yes, Mr. Chairman.
14 Thank you. Good morning, everyone.
15 We have three pieces of business in front 16 of us. But before we get to that, in the form of 17 letter writing we have a letter that we're going to 18 consider on boron redistribution, and specifically on 19 the topic of boron dilution in the downcomer of the 20 NuScale design.
21 We have a second letter that I call the 22 final letter. That would be our recommendation of the 23 committee on the DCA application. And now we have a 24 slight amendment, so to speak, to that in the form of 25 considering a standard design authorization as well.
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9 1 And, thirdly, we have a very rough draft 2 letter that we might get to later in the week to 3 consider, and that is observations and lessons learned 4 from our NuScale review.
5 So, that is the major business in front of 6 us. But, before that, I believe we're going to hear 7 from the staff about the request from NuScale to 8 consider -- or, actually, NuScale has submitted a 9 standard design application. So, we'll do that.
10 We then, I believe, should take, gather 11 any other information that we feel is necessary for 12 preparation of our letter reports because once we 13 transition to letter reports, then the deliberations 14 are amongst the committee, and the requests for staff 15 support or other input from the applicant is then --
16 should only then be a matter of factual corrections 17 and such, and not evolve into a situation where 18 they're participating in the letter writing.
19 So, with that, I think at this juncture we 20 should turn to the staff. And I don't know if that's 21 Anna Bradford who is going to lead off or --
22 CHAIR SUNSERI: Walt, NuScale. I think 23 NuScale is going.
24 MEMBER KIRCHNER: NuScale first. Okay, 25 sorry, my mistake. Thank you, Mr. Chairman.
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10 1 Yes, first a statement from NuScale and 2 then we'll proceed to the staff. Thank you.
3 From NuScale?
4 MR. MELTON: Yes, sir. Mike Melton, 5 Manager of Licensing. Ready to go.
6 MEMBER KIRCHNER: Go ahead, Mike.
7 MR. MELTON: Okay, thank you. And good 8 morning, all.
9 Yes, so the purpose of this first 10 discussion is to make a notification that NuScale has 11 submitted a letter on the docket on July 13th. And 12 the purpose of this letter is to request approval of 13 the NuScale design as described in the NuScale DCA 14 under Subpart Echo of standard design approvals 15 covered in 10 CFR Part 52, upon completion of the 16 staff's review and issuance of the final safety 17 evaluation report; issuance of the SDA document, 18 completion of the staff and the ACRS' technical review 19 of the NuScale power small module reactor design.
20 The technical review of the NuScale DCA 21 encompasses requirements for review of SDA application 22 set forth in 10 CFR 52.139, Standards for Review of 23 Applications.
24 In order to complete this process, NuScale 25 also requests that the Advisory Committee on Reactor NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.
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11 1 Safeguards consider the same docketed and reviewed 2 information as a basis for issuing a report pursuant 3 to 10 CFR 52.53. I believe that's your final letter.
4 And also include 10 CFR 52.141 for the NuScale SDA.
5 What we understand is, this is part of our 6 approval process and, therefore, the reason for the 7 letter at this time and this juncture in the review.
8 Any questions for us, please?
9 VICE CHAIR REMPE: I have a small question 10 just out of curiosity. Your letter requesting the SDA 11 was dated February 24th, 2020. Why is this coming up 12 on July 13th in your second letter? Did something 13 change where you planned to do it further out and now 14 it's earlier?
15 MR. RAD: I can answer that one.
16 MR. MELTON: Yes. Essentially it was a 17 course correction.
18 Okay, Zack. I will turn it over to Zack 19 at this point. Thank you.
20 MR. RAD: So, yes, Joy. Thank you. This 21 is Zack Rad, NuScale Power. I'm the Director of 22 Regulatory Affairs, for the record.
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12 1 the staff's FSER. And we were corrected on the need 2 for the timing prior to the ACRS' final letter.
3 That's all.
4 So, we had an internal misunderstanding of 5 the timing.
6 VICE CHAIR REMPE: Thank you.
7 CHAIR SUNSERI: Members, further questions 8 on the SDA from NuScale?
9 MEMBER PETTI: This is Dave Petti. We 10 need to have reflected -- we need to reflect this in 11 our 52.53 letter?
12 CHAIR SUNSERI: Yes, that's correct.
13 MEMBER PETTI: Okay, thanks.
14 MEMBER BALLINGER: Yeah, this is Ron. We 15 did exactly this for the APR1400. It was very 16 straightforward, just some additional wording.
17 MR. DUDEK: So, this is Michael Dudek.
18 Can I -- did someone present for the NRC? I was on a 19 phone call with Larry Burkhart on the back channel.
20 CHAIR SUNSERI: Michael, we haven't got to 21 the staff yet.
22 MR. DUDEK: Okay, fine.
23 CHAIR SUNSERI: So, your turn's coming up 24 in just a moment.
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13 1 interjecting.
2 CHAIR SUNSERI: So, members, any further 3 questions on the SDA of the applicant?
4 (No response.)
5 CHAIR SUNSERI: Hearing none, then let me 6 turn to the staff on this topic.
7 MR. DUDEK: So, this is Michael Dudek.
8 I understand that this has been a little 9 bit of confusion because we just got a letter on July 10 13th on NuScale formally submitting the SDA for NRC 11 review.
12 Now, I'd like to just go back to a little 13 bit of background information. In December of 2016, 14 NuScale submitted a design certification application 15 for its design. NRC staff reviewed that DCA 16 application which contains information that also 17 supports the NuScale standard design approval.
18 A standard certified design is codified by 19 rule.
20 A standard design approval is a staff 21 approval and is not codified by rule.
22 The FSER for the DCA when it is completed 23 will present the staff's evaluation and findings 24 concerning the NuScale standard design.
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14 1 NuScale notified the NRC staff of NuScale's intent to 2 request a standard design approval in accordance with 3 10 CFR Part 52 Subpart E. NuScale SDA is based on 4 NuScale's DCA design. NuScale also informed the NRC 5 of its plans to seek review approval of an SDA 6 application content not specifically required by 7 Subpart E.
8 Now, this new letter, dated July 13th, 9 2020, NuScale formally submitted its standard design 10 approval for the NRC's review. We immediately sent 11 that over to the ACRS so that it could be incorporated 12 into this meeting.
13 The SDA is similar to and contains part of 14 the NuScale design as described in the NuScale DCA 15 under Subpart E, Standard Design Approvals of Part 52.
16 And upon completion of the staff's review and issuance 17 of the final safety evaluation FSER, the contents of 18 the application will be made public and we will move 19 that forward.
20 The NRC staff, since that submittal of the 21 July 13th letter, has confirmed that the DCA and its 22 references contain the design information that Subpart 23 E of 10 CFR Part 52 requires for the standard design 24 approval. And we have incorporated that information 25 into FSER Chapter 1, which includes -- now includes a NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.
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15 1 reference to NuScale's July 13th, 2020 SDA request.
2 And this new SDA comprises a subset of the 3 DCA requirements.
4 And based on that review of DCA 5 application and what we need for the SDA, the staff 6 concludes that the information in the DCA about 7 NuScale's design complies with the requirements of 8 Subpart E of Part 52.
9 The NRC staff also finds that the 10 application for request for approval of the SD 11 application, not specifically required by Subpart E, 12 is acceptable.
13 And going forward, we seek acknowledgment 14 from the committee that the SDA is in process and will 15 be, potentially be approved by the NRC staff. And the 16 NRC staff will move forward after this meeting and 17 publish its determination in the Federal Register as 18 to whether or not the design is acceptable, subject to 19 the appropriate terms and conditions.
20 I think you've all seen the table for the 21 comparison of Subpart E and the SDA. Staff has 22 reviewed that and the delta therein, and has made that 23 finding.
24 So, with that said, I open it up to any 25 comments that the committee has.
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16 1 CHAIR SUNSERI: Members of the committee?
2 VICE CHAIR REMPE: So, this is Joy. If I 3 could ask a couple of questions of the staff.
4 CHAIR SUNSERI: Go ahead.
5 VICE CHAIR REMPE: First, I'm curious with 6 all the carve-out associated with the DCA for the 7 NuScale design and how the staff, and when have they 8 ever had carve-outs in a situation like this? It did 9 not occur with the APR1400, and how the staff would 10 deal with the carve-outs if someone were to move on 11 the SDA before the rule occurred?
12 And the other question I have is, and I 13 was looking to this table where it talks about 14 intended use of the reactor, there has been some noise 15 with the MOU that the DOE has regarding the U.S.
16 reactor that one of the two modules will be used for 17 testing. And how would that be dealt with with the 18 SDA if something were to be progressing with the 19 design based on this SDA?
20 Now, I do know they were talking about a 21 power upgrade and all these other things that are 22 beyond. I'm pretending that you're going to use the 23 SDA as it is, go forward, start doing construction 24 with it, and then someone says, well, okay, we'd like 25 to do testing with it. Can the staff talk about that NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.
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17 1 as well as the carve-out issue, please?
2 MR. DUDEK: So, I can address the first.
3 And I think, and I may need help with the second 4 piece.
5 But from what I've gleaned from my staff, 6 and in talking to the APR1400 owner -- and this was 7 brought up during that time about carve-outs and 8 exemptions -- I think our letter and our Federal 9 Register Notice will have to acknowledge both the 10 exemptions and the carve-outs as being unique for this 11 certified design.
12 I think we are still looking into that and 13 seeking OGC insights on that. But I assure you we 14 will iron that out.
15 And remember, as for the second, the SDA, 16 the snapshot on time on the certified design. So, I 17 think, Anna, do you have any insights on the testing 18 or using it for the second part of Joy's question?
19 MS. BRADFORD: Hi. This is Anna Bradford 20 from NRR. Yeah, one.
21 One thing just to add to what Mike just 22 said about the SDA and the carve-outs. I mean, a 23 simple way to think of it is if it's not approved in 24 the certification, it's not approved in the SDA.
25 Right?
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18 1 So, if we have not made a determination on 2 something in the design certifications phase, we also 3 will not have made a determination on that in the SDA 4 space. They go hand in hand.
5 The testing part, we have not, I will say, 6 officially heard from UAMPS that that's their 7 intention or how they would go about it or how they 8 would want the licensing for that to work. So, I'm 9 not sure we can answer that question yet.
10 VICE CHAIR REMPE: Okay. That helps.
11 And I, again, if they have a carve-out, 12 and let's be real optimistic and say they're going to 13 have not only a UAMPS one with this carve-out, and 14 they also are going to have one at TVA at their site, 15 the first person who comes in is the applicant to deal 16 with it on the UAMPS side may have one way of dealing 17 with it, and the staff approves it. But then the 18 second application with the SDA at a different site 19 may deal with it differently, but the staff each time 20 would evaluate it.
21 Is that true?
22 MS. BRADFORD: Yes. That is correct.
23 VICE CHAIR REMPE: That helps. Thank you 24 very much.
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19 1 this question. I mean, I'm kind of a governance-2 minded guy here and I'm just a little unclear on the 3 governance right this moment here.
4 So, let me ask a question. This is for 5 Michael Dudek. Maybe Anna can chime in on this.
6 But, so where is -- so, the ACRS, we are 7 an advisory committee. We don't approve the SDA, we 8 recommend approval, or whatever we're going to 9 recommend on these things. And we do that based on 10 review of the staff's work.
11 So, is the staff's work on the SDA going 12 to be sufficiently complete and have a finding such 13 that we can, you know, agree or disagree on that 14 finding, I guess, or advise on that finding?
15 MR. DUDEK: Yes. Can I --
16 CHAIR SUNSERI: Is this what you're about 17 to say here? You just got this information on the 18 13th, and I don't know, have you updated all your 19 documents and, you know, got that, what's going to be 20 before us properly so we can do our role?
21 MR. DUDEK: Yes. So, the project manager 22 has appropriately updated Chapter 1. And that's what 23 I was discussing with Larry Burkhart is kind of the 24 nuts and the bolts of the approval of that chapter.
25 We have sent you the updated chapter.
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20 1 However, I have not -- we have not officially declared 2 that in ADAMS yet. So, Larry Burkhart and I were 3 discussing the finer points of how we were going to 4 get that done.
5 But, yes, the finding has been updated in 6 Chapter 1. And we have essentially made that finding.
7 CHAIR SUNSERI: It was looking --
8 MS. BRADFORD: So, this is Anna Bradford.
9 CHAIR SUNSERI: -- at the process though, 10 right, so that's what you were saying?
11 MR. DUDEK: I'm sorry, I didn't hear your 12 question, sir.
13 CHAIR SUNSERI: So, what I thought I --
14 so, if I understand what you were saying, though, the 15 safety evaluation report has been updated but it 16 hasn't gone through all its final approvals yet. Is 17 that accurate?
18 MR. DUDEK: That is correct.
19 CHAIR SUNSERI: Okay, thank you.
20 MEMBER KIRCHNER: Mike. Michael, this is 21 Walt Kirchner. Do you have an estimate about how much 22 time that would take you?
23 MS. BRADFORD: Can I jump in here for one, 24 can I jump in here for one second?
25 MEMBER KIRCHNER: Yes. Go ahead, Anna.
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21 1 MS. BRADFORD: Thank you.
2 I just want to make it clear this is 3 almost just an administrative check. I mean, it's not 4 change -- we're revising Chapter 1 of the SE to say 5 that we've made findings under the SDA portion of the 6 regs. But it is not going to change the technical 7 content of our SE.
8 You can think of it as sort of the SDA is 9 encompassed by the design certification review. So, 10 really it's almost just changing a few sentences in 11 Chapter 1, which is the introductory part, to say we 12 have looked at it under the requirements of the SDA 13 and this is okay.
14 But, I don't want to leave you with the 15 impression that we're going back and changing, you 16 know, large numbers of chapters of the SE or anything 17 like that. When you ask for a schedule that's not 18 what this entails.
19 CHAIR SUNSERI: Yes. Thanks for that 20 update, Anna.
21 MEMBER KIRCHNER: Yes. Thank you, Anna.
22 Because I was going to pose a question just for the 23 public record along those lines that this doesn't 24 require a substantive change to the FSER. It will be 25 reflected in Chapter 1.
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22 1 MS. BRADFORD: Correct.
2 CHAIR SUNSERI: Yes. But, Walt, so, I 3 mean, my question though, my committee concern might 4 be is this: so, let's say that, you know, we end up 5 the week and we write a letter and we say -- and I'm 6 just forecasting, I'm not saying this is what the 7 letter is going to say or not -- but let's just say we 8 come to the conclusion that we recommend the DCA and 9 the SDA be approved. Okay. But the SER hasn't been 10 finalized and we haven't gone through all the stuff, 11 and we haven't seen the final. (Phone rings.) -- a 12 reason as quickly as this came up it goes away and you 13 end up not approving the SDA, and then we're out on 14 the record having said we recommend you approve it.
15 So, I guess technically then you could 16 say, well, we didn't approve it so your recommendation 17 is still good. I don't know. I just seems awkward to 18 me.
19 MEMBER KIRCHNER: Yes, I agree. That's 20 why I was asking Michael what an estimated completion 21 date is for filing that FSER so that we're not out 22 there ahead of them, so to speak, in our 23 recommendations.
24 MR. DUDEK: So, if I could, I think this 25 meeting has been proposed to span a couple of days.
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23 1 I think we have the opportunity to work with the PM 2 and to work with the staff on trying to get that 3 document finalized. And when we do, we can let you 4 know, and we can keep you updated as this meeting 5 progresses.
6 MEMBER KIRCHNER: Okay. And then we'll 7 trust but verify.
8 MR. DUDEK: Correct.
9 MEMBER KIRCHNER: It will take us time to 10 get our official letter out as well. As long as we're 11 not looking at a process that goes on for several 12 months with regard to the SDA.
13 MR. DUDEK: I think we're looking at days, 14 a week at the most. So, I think we could be -- we 15 could have that, that final ML number to you in short, 16 in the relatively short term.
17 MEMBER BROWN: What does that mean?
18 MR. DUDEK: We could have that Chapter 1 19 done in fairly short term, maybe days or within a week 20 or so. So what, by the time this letter, your letter 21 is finalized you will -- I would hope that the staff 22 would be able to have that information to you.
23 MEMBER BROWN: We're finalizing the letter 24 this week, aren't we, Matt, Walt?
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24 1 deliberations. But there is a process that we go 2 through, Charlie. And the chairman, our committee, 3 can hold the letter until he is satisfied that due 4 process has been, or due diligence has been observed 5 on our part and that this has, the FSER Chapter 1 has 6 been completed.
7 MEMBER BROWN: Yeah, I understand. I 8 understand that part, Walt. I'm just trying to 9 connect, this, is this SDA strictly for UAMPS or does 10 it apply to anybody else that comes in?
11 MS. BRADFORD: So, this is Anna Bradford 12 again.
13 The SDA is just a generic licensing 14 finding, I'll say. So, no, it's not just UAMPS.
15 Someone else could refer to it in a future application 16 if they wanted to.
17 MEMBER BROWN: Does that mean -- I'm still 18 trying to get a grip on it. I'm sorry I'm so, so 19 short on this.
20 Effectively, it doesn't change the 21 certified design. They can't change the certified 22 design at all as a result of an SDA?
23 MS. BRADFORD: In this case, in this case 24 the scope of the SDA and the scope of the DC are 25 pretty much the same.
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25 1 MEMBER BROWN: What does that mean?
2 What's "pretty much" --
3 MS. BRADFORD: The design, the design that 4 we're approving in the SDA is the same as the design 5 that we're approving in the design certification.
6 There's not a difference in the design, it's the same 7 thing.
8 It's almost a different piece, just a 9 different piece of paper that we're giving them to say 10 we've completed our technical review and we find the 11 design acceptable.
12 MEMBER BROWN: Okay. So, I'm going to be 13 parochial here for a minute. We have part of the DCA 14 and the SER and all of the design certification 15 documents. There's a Chapter 7 which describes all 16 the reactor trip safeguards and the rest of the 17 architecture for all those systems, control systems.
18 Yes, --
19 MR. DUDEK: So, to answer your question, 20 the certified design will not be changed. The SDA can 21 encompass more information than the certified design 22 but it cannot encompass less.
23 MEMBER BROWN: It's not a matter of 24 encompassing, it's a matter of can they change the 25 architecture for the trip systems and the safeguard NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.
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26 1 systems when they are applying an SDA? Or does it 2 have to remain --
3 MS. BRADFORD: Only if they --
4 MEMBER BROWN: -- what's described in the 5 DCA as we certified it, as we write our letter on it?
6 MS. BRADFORD: So, this is Anna Bradford 7 from NRR again.
8 Remember, it's technically not certified 9 until the rulemaking is done. So, a lot of applicants 10 don't want to wait that six to nine months for the 11 rulemaking to be done, so they ask for an SDA to be 12 issued at the end of our technical review, which is 13 now.
14 So, what the SDA is, is it provides them 15 some formal feedback from the regulator that we looked 16 at your design and it's okay. If someone then wants 17 to refer to that SDA in a future application and they 18 want to change something, they would need to come back 19 and talk to us about that.
20 MEMBER BALLINGER: This is Ron.
21 With the APR1400 it really boiled down to 22 time in the sense that with the SDA you really have 23 approval, in effect, but the final rule takes, like 24 Anna said, I think six to nine months. And so, it's 25 really a matter of timing.
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27 1 MEMBER BROWN: Ron, I understand that part 2 of it on the timing now that it was pointed out. My 3 only real question, and I've asked it but I haven't 4 gotten a no to it, is that fundamentally what we have 5 reflected in Chapter 7 has to be reflected in whatever 6 design, regardless of somebody's desire to use an SDA 7 prior to the rulemaking.
8 The rulemaking contains something. I 9 mean, if somebody decided to come back, I guess the 10 rule could say, hey, we're going to change part of the 11 DCA, I presume.
12 MS. BRADFORD: In either case, if a future 13 applicant was referring to the SDA or the certified 14 design they can propose to do a different approach or 15 do something different, and then the staff would 16 review that.
17 MEMBER BROWN: I got that. That part I 18 pretty much understand.
19 MS. BRADFORD: Okay.
20 MEMBER BALLINGER: Okay. I just find it 21 hard to write all this.
22 MEMBER KIRCHNER: Other members?
23 MEMBER BROWN: I was just trying to get a 24 hold on this. That's all. I'll quit.
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28 1 satisfied?
2 MEMBER BROWN: My stomach is rolling over.
3 How about that?
4 MR. DUDEK: So, I think I can, very 5 hopefully, more clearly answer your question.
6 The SDA as it's going to be approved will 7 not change anything in the certified design. So, 8 Chapter 7 will remain the same. And does that --
9 MEMBER BROWN: Okay. I went through your 10 table and every item in it. That's what my concern, 11 that's what my thought was until I started hearing 12 this conversation. I thought it changed nothing at 13 all. It effectively changed acronyms and a few other 14 administrative missing lights.
15 So, I'll, I'll say I'm satisfied so we can 16 walk off right now. I'm sorry for the delay.
17 MEMBER KIRCHNER: No, that's fine, 18 Charlie. It's better to have this, thrash it out now 19 than when we're in the letter writing phase.
20 Other members?
21 MEMBER BLEY: This is Dennis Bley.
22 It seems to me that when we get through 23 our letter writing we can, as we have a motion to 24 approve the letter we can include authorization for 25 our chairman to either withhold it or remove a NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.
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29 1 sentence that refers to the design approval if it's 2 not in place by the time we're ready to issue the 3 letter. But we can address that at the end of our 4 letter writing.
5 MEMBER KIRCHNER: Thank you, Dennis. That 6 was my thinking as well. So, there's a way for us to 7 address Matt's governance question.
8 Other members?
9 MEMBER DIMITRIJEVIC: Well, you know, I'm 10 sort of reasoning will there be a change in the 11 language for carve-outs? Because we will have to 12 reference those carve-outs in our letter. Will that 13 be different language now?
14 MS. BRADFORD: So, this is Anna Bradford 15 from the NRR.
16 I think it might be worded different 17 because the SDA is not a rulemaking, so the language 18 of the carve-out would not say, you know, --
19 MEMBER DIMITRIJEVIC: Right.
20 MS. BRADFORD: -- this information is not 21 receiving finality in the rule. But the technical 22 description would stay the same.
23 MEMBER DIMITRIJEVIC: Yeah, it can be --
24 MS. BRADFORD: The carve-outs -- Go ahead.
25 I'm sorry.
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30 1 MEMBER DIMITRIJEVIC: Then it's okay 2 because that will be language we will need to put in 3 our final letter. So, it will be good to have the 4 final, you know, language on this is how it's going to 5 be in the SDA.
6 MEMBER BLEY: This is Dennis Bley again.
7 Anna, maybe this would help. Can you tell 8 us what an applicant, well, the holder would be able 9 to do, what can you do differently with a design cert 10 than with a standard design approval? And that might 11 help.
12 MS. BRADFORD: That's a good question.
13 So, a design certification is afforded 14 much more finality by the agency, so that once it's 15 completed the rulemaking it is final and it's very 16 difficult for us to change it.
17 An SDA has less finality from the agency 18 and, therefore, gives future applicants less certainty 19 that nothing in it could be revised.
20 I don't know if that helps. But an SDA is 21 more open to changes being required by the regulator 22 in the future than a design certification is.
23 VICE CHAIR REMPE: But isn't there a bit 24 more you can do with it, because the rule won't come 25 out for a while? And if you have a staff-approved NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.
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31 1 SDA, can't you go ahead and try and seek your 2 construction permit, for example?
3 MS. BRADFORD: Sure. Yes, you absolutely 4 could. But when the applicant comes in for that 5 construction permit and they refer to the SDA, our 6 findings in that SDA do not have the level of finality 7 that our findings will eventually have in the design 8 certification.
9 It's almost like you could think that 10 since the design certification is a rule, and an SD --
11 you can almost figure that the way we talk about rules 12 and guidance, so rules have a certain level of 13 requirements and you must conform with them, and then 14 we have guidance. And it's more like that's one way 15 you could do it. But the agency might look at another 16 way.
17 I think of it that way. The design 18 certification is a rule, it is locked down in terms of 19 finality. An SDA does not have that same level of 20 finality.
21 MEMBER BROWN: Can I phrase that? The DCA 22 you're waiting on the rule to come out six to nine 23 months. That's what you said. Takes time.
24 If somebody proceeds with an SDA, they are 25 in a way taking a risk that there will be no change NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.
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32 1 when the rule comes out?
2 MS. BRADFORD: That is true, yes.
3 MEMBER BROWN: So that is a risk, it's a 4 risk, if they're willing to take that risk on the 5 assumption that the DCA, as final as it is, is not 6 going to make any changes or nothing comes up in that 7 9-month period. So, it allows them to get started, 8 even though the finality that you talk about has not 9 been granted.
10 MS. BRADFORD: Correct.
11 MEMBER BROWN: Okay. Now I've got a, I've 12 got a better understanding of what you're talking.
13 It's really, it's really a risk by the guy that gets 14 started before he knows whether he's going to be okay 15 or not, if he wants to. That I can --
16 (Simultaneous speaking.)
17 MS. BRADFORD: No, I think that that is 18 definitely one way to think about it. It does not 19 have the same finality as if you waited nine more 20 months for the rule.
21 MEMBER BROWN: I'm trying to put it in 22 perspective for what I used to have to deal with back 23 in my day in NR. Frequently our vendors would proceed 24 with a design change based on meetings we had. I had 25 to write a letter saying that's what to do to get it NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.
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33 1 through. But they would proceed, proceed in the hopes 2 that we didn't tell them to do some tweak on it in 3 order to keep moving. So, that's the way I view this 4 thing, the SDA application.
5 MEMBER BLEY: Anna, it's Dennis Bley 6 again. You talked about this earlier, but as this 7 talk goes on I want to revisit one part.
8 Your SER, will it, will it -- will there 9 be a separate SER for the design approval or will it 10 just be referred? This is going back to the carve-11 outs. You recommended carve-outs in your SER for the 12 design cert which will end up, if the Commission 13 approves, as part of the rule.
14 How do those carve-outs, how are they 15 retained as part of your design approval?
16 MS. BRADFORD: So, the question you just 17 asked is important. There is not a separate SE for 18 the SDA. The SDA and the design certification are 19 based on the same SE. So, there's not a separate 20 document.
21 The only separate document --
22 MEMBER BLEY: So the carve-out is still 23 there?
24 MS. BRADFORD: Yes. But if you go back 25 and look -- and we can send it to you if you don't NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.
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34 1 have it readily accessible -- the only thing we issue, 2 that the agency issues for an SDA is a letter that's, 3 like, two or three pages. And we send that to the 4 applicant and we say, you've met the requirements for 5 the SDA. Our SE is at such and such. It's the same 6 SE as for the design cert. And that's it, that's what 7 they get.
8 MEMBER BLEY: Okay. That, that makes me 9 much more comfortable. Thank you.
10 MS. BRADFORD: Sure.
11 CHAIR SUNSERI: Hey, Anna, this is Matt.
12 I hate to keep bringing these questions up. But just 13 one more question.
14 We're well versed in how a DCA, an 15 approved DCA gets changed, the deviations and all that 16 stuff. What is the change -- is there a 10 CFR 50.59-17 like process for the SDA?
18 MS. BRADFORD: I think that -- I don't 19 think there's a 50.59-like process. I think what 20 would happen is the applicant would come in and say 21 that there's a COL applicant, and they want to refer 22 to the SDA because they don't want to wait for the 23 rulemaking.
24 In their COL application they would point 25 out places where they want to deviate from the SDA and NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.
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35 1 explain why they want to do that. And we would review 2 that.
3 CHAIR SUNSERI: Oh, okay. Thank you, 4 that's helpful. Appreciate it.
5 MEMBER KIRCHNER: Anna, this is Walt 6 Kirchner. Just one last request.
7 All the proposed rule -- probably not 8 using the right terminology when we say "carve-out" --
9 but all the proposed language that would be in the 10 rule is currently in the FSER; is that correct?
11 MS. BRADFORD: The -- not the exact 12 language. Like, this doesn't say necessarily, you 13 know, this rule is not providing finality. But the 14 technical discussion talks about areas where we 15 couldn't reach a conclusion based on various things.
16 So, it's all written up in the SE where we can find 17 that.
18 MEMBER KIRCHNER: Would it be just so, 19 since the SE is a rather large document, would it be 20 too much to ask for a review, for your staff to just 21 give us a pointer list of all the places where you 22 have inserted that kind of language in the FSER?
23 MS. BRADFORD: The language that supports 24 the carve-out?
25 MEMBER KIRCHNER: Yes.
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36 1 MS. BRADFORD: Yes. We could do that.
2 MEMBER KIRCHNER: I'll be much obliged.
3 That would help us ensure that we're complete in our 4 review. Thank you.
5 MS. BRADFORD: Sure.
6 MEMBER KIRCHNER: Other members?
7 MEMBER DIMITRIJEVIC: This is Vesna 8 Dimitrijevic again.
9 Do all the commitments, like COLA items, 10 ISEC items, you know, the -- do those all apply 11 equally?
12 MS. BRADFORD: So, the COLA items -- Let 13 me back up.
14 The regulation for a COL application tell 15 the COL applicant that they need to address the COL 16 items. There is not something similar in the SDA 17 regulations that say you have to address the COL item 18 because it's an SDA not a COL.
19 But the COL items are documented in our 20 SE. So, the staff would know, hey, here are things 21 that we thought a future applicant would need to 22 address. So, they would still all be on the record in 23 our FSER about things that needed to be addressed by 24 the future applicant, whether they're using the SDA or 25 the design cert. If that makes sense.
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37 1 MEMBER DIMITRIJEVIC: Okay.
2 MR. MOORE: Mr. Chairman, this is Scott 3 Moore. May I address the committee?
4 CHAIR SUNSERI: Please do so, Scott.
5 MEMBER KIRCHNER: Yes, please go ahead.
6 MR. MOORE: So, I have a question for the 7 committee.
8 Does the committee need any more 9 information from the staff in order to write its final 10 letter this week, in addition to what Chairman 11 Kirchner just asked for?
12 VICE CHAIR REMPE: Well, I think we're 13 going to hear from the answers to those questions, 14 Scott; right? And the staff's going to be giving us 15 information. So, we aren't sure yet; right?
16 MEMBER MARCH-LEUBA: One member of the 17 committee -- this is Jose -- has technical questions 18 I want to raise whenever I'm allowed.
19 MEMBER KIRCHNER: Yes.
20 MEMBER MARCH-LEUBA: I would like to get 21 more information from them, yes.
22 MR. MOORE: Yes. They are going to go, I 23 believe they are going to go through that this 24 morning.
25 Anna, do you understand what the NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.
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38 1 committee's asking?
2 MS. BRADFORD: Yes.
3 MR. MOORE: Okay. Besides that, is the 4 committee asking for any other information about the 5 carve-outs in writing that you need this week?
6 MEMBER KIRCHNER: I don't believe so, 7 Scott. It's just that such a list, a pointer list, 8 would help us just be sure that we're complete in our 9 work. That's, that's why I made that request of Anna 10 Bradford.
11 MR. MOORE: Okay. And then for the staff, 12 for Anna and Mike, just to be clear, the committee is 13 doing letter writing this week on the final letter.
14 And I think you heard that the letter then will be 15 prepared. The committee would vote it out this week 16 in one way or another, depending on what the letter 17 says. And the chairman would sign out some final 18 letter next week, in probably the middle to later part 19 of next week.
20 So, it would need the staff's action on 21 the SER by that point. Just to give you a sense of 22 timing.
23 Thank you, Mr. Chairman. That's all I 24 have to say.
25 MR. CHOWDHURY: Mr. Chairman, this is NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.
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39 1 Prosanta Chowdhury, Project Manager.
2 May I have a few seconds to clarify 3 something that will be very helpful to the committee?
4 CHAIR SUNSERI: All right. Yes, please 5 proceed. Yes.
6 MR. CHOWDHURY: Yes, okay. This is 7 Prosanta Chowdhury. I'm Project Manager.
8 Referring back to the request for pointers 9 to the carve-out, Chapter 1, the draft version that we 10 have shared with the ACRS staff this morning, on page 11 1-3 of Chapter 1 has the pointers to all those carve-12 outs in one of the paragraphs.
13 CHAIR SUNSERI: Okay. Thank you, 14 Prosanta, that's very useful. We'll take a look at 15 it.
16 I did not look at the FSER this morning 17 over breakfast, but we'll get to it. Thank you.
18 MR. CHOWDHURY: Conclusion of Chapter 1 19 also talks about, clearly identifies those carve-outs, 20 but the pointers are on page 1-3.
21 CHAIR SUNSERI: Thank you very much.
22 MEMBER BLEY: Dennis Bley. One last 23 thing.
24 CHAIR SUNSERI: Yes, Dennis, go ahead.
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40 1 finish the letter I'd recommend to the members to read 2 part -- Section E of Part 52 on standard design 3 approval. It's really short and it will give you --
4 I think it will help. But it's a very short thing.
5 You can read it in five minutes.
6 MEMBER BROWN: Did you say Section E or D, 7 Dennis, of Part 52?
8 MEMBER BLEY: Echo, Standard Design 9 Approval. If you go to Part 52, you can't miss it.
10 MEMBER BROWN: Okay, thank you.
11 CHAIR SUNSERI: Thank you, Dennis.
12 MEMBER KIRCHNER: Okay.
13 MR. DUDEK:. So, Mr. Chairman, Michael 14 Dudek. Oh, go ahead.
15 MEMBER KIRCHNER: We could transition now.
16 We had posed, Mr. Chairman, we had posed after our 17 deliberations two weeks ago, we had several members 18 pose questions of the staff. So, I think we are at 19 that juncture in the proceedings to take on those 20 questions.
21 CHAIR SUNSERI: Yes. And just want to 22 confirm one thing. Did Michael Dudek want to make one 23 more statement? I heard you trying to break in there.
24 MR. DUDEK: So, my apology. I didn't mean 25 to break in. I just wanted to clarify whether we NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.
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41 1 still had that as a formal IOU or not. Did Prosanta's 2 clarification --
3 MEMBER KIRCHNER: I think that's 4 sufficient, Mike. I don't want to send you on another 5 chase. That helps.
6 MR. DUDEK: I understand. Thank you, sir.
7 MEMBER KIRCHNER: Thank you, Michael.
8 CHAIR SUNSERI: Okay, Walt, thanks for 9 that. Yes, I agree.
10 So, do you want to, do you want to take a 11 short break here for a few minutes before we get into 12 the next section since we're kind of shifting gears 13 then on the questions?
14 MEMBER KIRCHNER: Yes. That would be 15 good, Matthew. If we could, Mr. Chairman, if we could 16 take a 10-minute or 12-minute break and --
17 CHAIR SUNSERI: Yes.
18 MEMBER KIRCHNER: -- reconvene at, what, 19 10:40?
20 CHAIR SUNSERI: Well, I feel --
21 MEMBER KIRCHNER: 10:45?
22 CHAIR SUNSERI: Feel generous, yes, 10:45.
23 MEMBER KIRCHNER: Okay.
24 MR. SNODDERLY: Chairman Sunseri, this is 25 Mike Snodderly. I just have one clarification for NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.
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42 1 Mike Dudek.
2 CHAIR SUNSERI: Sure.
3 MR. SNODDERLY: So, for the public record, 4 eventually this transcript will be on the public 5 website, and I just wanted to confirm with Mike Dudek 6 that the table that you provided the committee 7 comparing Subpart D and Subpart E, I plan to make that 8 part of the record and attach it to the transcript.
9 I just wanted to make sure that that's publicly 10 available and that's okay to share that, that table 11 comparison.
12 If not, please get back to me. But if I 13 do not hear from you, I will add that to the record.
14 MR. DUDEK: I understand. And I will, I 15 will get back to you.
16 MR. SNODDERLY: Thank you.
17 MEMBER KIRCHNER: Thank you, Mike, both 18 Mikes. Thank you.
19 Okay, with the Chairman's permission, I 20 think we are now recessed until 10:45 Eastern Time.
21 (Whereupon, the above-entitled matter went 22 off the record at 10:29 a.m. and resumed at 10:45 23 a.m.)
24 CHAIR SUNSERI: This is Matt Sunseri. I 25 have 10:45. We are back in session. I'll being with NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.
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43 1 a roll call to confirm a quorum. Ron Ballinger?
2 MEMBER BALLINGER: Here.
3 CHAIR SUNSERI: Dennis Bley?
4 MEMBER BLEY: Here.
5 CHAIR SUNSERI: Charles Brown?
6 MEMBER BROWN: Here.
7 CHAIR SUNSERI: Vesna Dimitrijevic?
8 (No audible response.)
9 CHAIR SUNSERI: Walt Kirchner?
10 MEMBER KIRCHNER: Here.
11 CHAIR SUNSERI: Jose March-Leuba?
12 MEMBER MARCH-LEUBA: Here.
13 CHAIR SUNSERI: Dave Petti?
14 MEMBER PETTI: Here.
15 CHAIR SUNSERI: Joy Rempe?
16 VICE CHAIR REMPE: Here.
17 CHAIR SUNSERI: Pete Riccardella?
18 MEMBER RICCARDELLA: I'm here.
19 CHAIR SUNSERI: And I'll go back to Vesna?
20 MEMBER DIMITRIJEVIC: Here. I'm here.
21 CHAIR SUNSERI: Okay. Thank you. All 22 right. We have a quorum. And I would just start by 23 saying thank you for the staff and NuScale's 24 explanation of what was going on with the submittal of 25 the SDA. We have a clear picture of what work is NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.
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44 1 before us now for the rest of the week incorporating 2 that request.
3 We are going to move on to the next phase 4 of the discussion today which as you recall at our 5 last round of meetings, we asked members to pose 6 questions to staff that we would need to have 7 addressed to finish our deliberation. Staff is now 8 prepared to address those questions, and Walt and I 9 have discussed the sequence of how this session is 10 going to be conducted. So Walt is going to facilitate 11 it, and I'll turn it over to Walt to describe how 12 we're going to go about this. So Walt?
13 MEMBER KIRCHNER: Okay. So we would like 14 to first hear from the staff addressing the questions 15 that members had posed. When we do that, perhaps if 16 the staff could just summarize the question and then 17 provide their response because we're on public record.
18 And then we'll go to deliberations and input from 19 members.
20 Member March-Leuba has made a point that 21 he would like to make a statement and we'll go from 22 there and try and conclude our deliberations. If we 23 need to or if the staff feels they need to go into 24 closed session to fully address a question, then we 25 should hold that to the end. So we only break from NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.
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45 1 open to closed once. And then we would do whatever is 2 necessary in closed session and then come back to open 3 session and a while for any public input. So with 4 that, I will now turn to the staff. Mike Snodderly, 5 who from the staff is going to lead us through this?
6 MR. SNODDERLY: I believe Ryan Nolan of 7 the staff. Is he available?
8 MR. NOLAN: Yeah, this is Ryan Nolan from 9 the staff.
10 MEMBER KIRCHNER: Okay. Ryan, go ahead, 11 please.
12 MR. NOLAN: Okay. This is Ryan Nolan from 13 the staff. I'd like to thank you for the opportunity 14 for the staff to provide responses to additional ACRS 15 questions. I'm going to start with Member Bley's 16 question and then we'll work back to the maybe the 17 more specific area questions when I'm done.
18 So Member Bley's question is, what 19 prevents the staff from asking how the operator will 20 stop an unplanned dilution before the shutdown margin 21 is eliminated as described in SRP Section 15.4.6. And 22 it's titled, inadvertent decrease in boron 23 concentration in the RCS for PWRs. Before I get into 24 the specifics of that question, I just want to take a 25 step back and just quickly maybe address at a high NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.
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46 1 level operator actions and their role within passive 2 designs.
3 And so NuScale performed their design 4 basis Chapter 15 analysis, assuming no operation 5 actions for a minimum of 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br />. I think we have 6 went over that many times at this point. This 7 approach is consistent with the Commission policies 8 for passive designs as well as industry guidance. So 9 by definition, we would not consider the NuScale 10 design to be passive if it required early operator 11 action in order to respond to or mitigate a Chapter 15 12 event.
13 In addition, SECY-93-128 establishes the 14 Commission policy that passive designs should be able 15 to cope on site for all design basis events for at 16 least seven days. So while previous passive designs 17 needed operator action and nonsafety systems around 18 the 72-hour mark to continue satisfying the safety 19 functions, NuScale has demonstrated through their 20 analysis that even up to seven days, operator actions 21 are not needed to satisfy those safety functions.
22 I'd also like to point out that keep in 23 mind that this is really just to establish the 24 licensing basis for the facility. In contrast or in 25 reality, this does not prevent the operators from NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.
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47 1 following their operating procedures and taking action 2 if needed. So I just wanted to provide a little bit 3 of perspective on sort of the role of operator actions 4 in passive design licensing.
5 Specific to the purpose of SRP 15.4.6, the 6 purpose of that transient is to address the potential 7 for unborated water addition to the RCS from external 8 sources such as CVCS. As pointed out in the question, 9 the 15.4.6 analysis typically must show that an 10 operator can reasonably identify and stop the 11 unplanned dilution before the shutdown margin is 12 eliminated. This SRP and the guidance was really 13 written for active plants, and so there's a lot of 14 prescriptive sort of review procedure and a focus of, 15 how long does it take the operator to identify or 16 isolate before the shutdown margin is eliminated?
17 Because NuScale has passed their design, 18 they demonstrated that the applicable regulatory 19 requirements were met with the use of automatic safety 20 actuation signals to isolate the largest source of 21 unborated water which for them is the de-mineralized 22 water system. And they showed that that isolation 23 occurs before the shutdown margin is lost. And so for 24 the purposes of this Chapter 15 analysis, NuScale 25 showed that the SAFDLs were met. You didn't lose the NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.
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48 1 shutdown margin, and no operator actions were needed.
2 Whereas I think the main focus of today's 3 meeting as well as the last couple ACRS meetings is on 4 the potential for an uneven boron distribution. But 5 that's really due to the natural transient progression 6 of extended passive cooling. And it's distinctly 7 separate from the transient that's identified within 8 Section 15.4.6.
9 I'll also note based on the analysis and 10 our conclusions, any post-event thermohydraulic 11 disruption to the RCS that would potentially impact 12 those SAFDLs would require multiple failures or 13 operator actions of commission. And that's why it was 14 not addressed because it's outside -- it's not 15 addressed within the design basis review because it's 16 outside of the Chapter 15 analysis. That doesn't mean 17 the staff didn't address that.
18 The misuse of nonsafety-related systems or 19 multiple errors of commission is addressed within 20 Chapter 19. And those conclusions are mainly 21 supported by Dr. Yarsky's white paper which we 22 discussed at the last meeting and I'm sure we'll be 23 discussing it again today. But ultimately, what I'd 24 like to point out is whether the SRP 15.4.6 is 25 appropriate guidance to use for a boron redistribution NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.
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49 1 analysis or for this phenomena.
2 The SRP is really there to identify what 3 the applicable regulations are and how the staff would 4 perform a review to demonstrate compliance with those 5 regulations. And the regulations that are identified 6 in 15.4.6 are the same regulations that we made 7 findings on for the uneven boron distribution 8 analysis. Mainly, GDC 10 for the SAFDLs is one of our 9 main focuses here.
10 And so our conclusions for the uneven 11 boron distribution is that even if you do get a 12 diluted downcomer or containment and there's no 13 operator actions, the SAFDLs are met for at least 72 14 hours1.62037e-4 days <br />0.00389 hours <br />2.314815e-5 weeks <br />5.327e-6 months <br />, and then as documented in Chapter 19, likely 15 beyond seven days if the operators don't do anything.
16 And so I'll pause here to take any additional 17 questions.
18 MEMBER BLEY: Good. This is Dennis Bley.
19 That's a nice, elaborate answer. My question, you get 20 a bit modified by the time it was presented to you, 21 but you knew what it was about. But I'll state it 22 again.
23 We've been told time -- many times during 24 this review that recovery is reserved for the COL 25 stage, and this would be a recovery action. Several NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.
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50 1 of us felt that it really should've been covered in 2 Chapter 15 because there was an identified 3 deteriorating state going on. And after the last 4 meeting and during the meeting, I had asked, what's 5 the specific regulation for guidance that says you're 6 not allowed to look at recovery to the COL stage or 7 that says you're finished at 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br />?
8 Well, we've kind of turned it around 9 because we want to be finished at 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br />. We must 10 be. I went looking through all the regulations and 11 found nothing hinting at this. I went to guidance, 12 and the only place I found anything related was in 13 this Chapter 15.4.6. And while, yeah, it's written 14 for injection from other sources, it's the nearest 15 thing to guidance on this situation that had been laid 16 out.
17 Nothing that I read in that section says 18 that if you're in a continuously deteriorating state, 19 you don't have to carry the analysis out to some end 20 point where you're not in that kind of a state. So 21 while the answer -- it reminds me a lot of something 22 I ran into doing work in another country where they 23 told me that the probability of failure in their scram 24 system was 10 to the minus 5th of demand. And I asked 25 for their analysis, and they said, well, there's a NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.
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51 1 standard that says it has to be that. So that's what 2 it is. We've kind of turned it back and forth here, 3 so I'm not convinced by the answer I was given.
4 Thanks, though, for --
5 MEMBER DIMITRIJEVIC: Yeah, I would like 6 to do some -- Ryan, I want to correct you in the two 7 facts you said. First you said the multiple errors of 8 commission are covered in Chapter 19. That's not 9 true. Chapter 19 specifically said that no important 10 errors of commission were identified.
11 And then you said the seven days is also 12 covered in Chapter -- I have a feeling that now a lot 13 of things are done in Chapter 19. But they're not 14 happening there. They're not covered there. So let's 15 just maybe you guys think they should be there, but 16 they're definitely not there.
17 Also, we're asking the write up. I have 18 one very specific scenario which is not what we are 19 discussing here. And this is the CVCS injection after 20 the ECCS partial failure. So the thing is which is 21 the question is here, are we in the stable -- you are 22 not in the stable condition after the prolonged ECCS 23 injection.
24 And then therefore the Chapter 15, I think 25 the objective of Chapter 15 is to leave the things in NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.
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52 1 the stable condition, and this is not the case there.
2 So this is why this recovery action should be 3 discussed. That's my comment. I just want to correct 4 about this, what's in Chapter 19 and what is not.
5 MR. NOLAN: Sure. Yeah, thank you for 6 that clarification. When I was referring to Chapter 7 19, I was referring to the staff safety evaluation and 8 the conclusions that are included in that SE. And I 9 think the place you will see the seven-day finding is 10 in Section 19.3, specific to the review of whether or 11 not -- it has to do with the regulatory treatment of 12 nonsafety systems review directly associated with the 13 Commission policy for seven-day coping. And so the 14 19.3 does include a conclusion on seven days.
15 MEMBER DIMITRIJEVIC: Okay. Well, 16 usually, when we say Chapter 19, we don't apply it to 17 even the regulatory treatment of non-safety systems in 18 Chapter 19. Chapter 19 usually refers to the PRA. So 19 that's why I give a correction.
20 MR. NOLAN: Yeah, the SRP for RTNSS is 21 Section 19.3, and that's where the applicant put that 22 information into the application. And so that's why 23 it shows up in Chapter 19.
24 MEMBER MARCH-LEUBA: Hey, this is Jose.
25 Since I'm the troublemaker, I would like to throw my NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.
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53 1 full support on what Dennis said. And he said it much 2 more eloquently than I could. So I just wanted to say 3 that I support what he said.
4 MEMBER KIRCHNER: Dennis, may we move on?
5 I obviously will be --
6 MEMBER BLEY: Yeah, I'm done, Walt.
7 MEMBER KIRCHNER: -- coming back to this.
8 Yeah, we'll come back and obviously --
9 MEMBER BLEY: I think there's better ways 10 to deal with this separately. So I think we'll come 11 back to it in letter writing.
12 MEMBER KIRCHNER: Yes, yes. That's my 13 sense too.
14 MR. CORRADINI: So Walt, this is 15 Corradini. Can I just ask the presenter one question?
16 He said the EOPs can be -- or procedures can be used 17 to mitigate the situation. But I'm a little bit 18 confused. In this case, wouldn't I expect with some 19 sort of actuation that the operators are aware that a 20 dilution event is progressing that they would step in 21 and do something? Can you explain this? Maybe I 22 misunderstood your explanation.
23 MR. NOLAN: Yeah, I didn't want to overly 24 speculate how the procedures would be written. I was 25 just trying to make the point that we would expect the NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.
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54 1 operators to follow their procedures, even if they go 2 beyond sort of the minimum licensing basis of the 3 facility. That's the only point I was trying to make.
4 There may be certain situations depending 5 on what the event is we wouldn't want the operator to 6 take an action. If you do have an ATWS LOCA event, it 7 may not be a good idea to unisolate containment to 8 prevent a dilution event. I just didn't want to 9 speculate all the different scenarios and how the 10 procedures may be written in the future.
11 MR. CORRADINI: But let me then restate it 12 differently just so I'm on the same page with what 13 you're saying. Your point is that a Chapter 15 event 14 is not identified that's a boron dilution event. Am 15 I understanding this correctly, because of the fact 16 that they isolate --
17 MR. NOLAN: It's not --
18 MR. CORRADINI: -- the de-mineralized 19 water system ahead of time? Am I understanding this 20 correctly?
21 MR. NOLAN: Right. Yeah, so 15.4.6 22 addresses unplanned boron dilution events as the 23 initiator. Uneven boron distribution, I wouldn't 24 necessarily consider it an unplanned boron dilution 25 event. That's just the natural progression of the NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.
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55 1 transient and the natural thermohydraulic response of 2 these passive cooling systems for this design. And so 3 I sort of see them as one's an initiating event, one 4 is not.
5 MR. CORRADINI: Okay. But then let me ask 6 the question another way. But we're all in agreement 7 that upon actuation of the ECCS, there will be a 8 situation where parts of the system will be a 9 different at boron concentrations than other parts of 10 the system and this will progress. But that's not 11 considered an initiating event. Therefore, the staff 12 does not look at it within a Chapter 15 context. Am 13 I understanding this correctly?
14 MR. NOLAN: No, no, no. We certainly 15 address this as part of 15.0. And within 15.0, uneven 16 boron distribution is addressed. And our conclusion 17 is that if the operator doesn't take any action which 18 is what the assumption is for Chapter 15, there is 19 sufficient shutdown margin in the core.
20 MR. CORRADINI: In the core? Okay.
21 MR. NOLAN: Yes.
22 MR. CORRADINI: All right. Okay. But I 23 think it didn't say it as precisely as you did. But 24 what you're then saying is that recovery is -- it kind 25 of goes back to Dennis' basic point which is, why is NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.
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56 1 recovery off the table to be considered here? And 2 your answer is because it's carried out after the 3 event and we're in a safe -- supposedly safe situation 4 post-event.
5 MR. NOLAN: Right. Our conclusion is this 6 condition with no operator action is a safe, stable 7 condition.
8 MEMBER BALLINGER: This is Ron Ballinger.
9 It's a little bit concerning. I mean, I understand 10 the rule, and I've read that part of it. But if you 11 know that, well, okay, for 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br /> or seven days or 12 whatever it is, everything is stable. But if you know 13 that 72.1 hours1.157407e-5 days <br />2.777778e-4 hours <br />1.653439e-6 weeks <br />3.805e-7 months <br /> later or two days, 0.1 day later the 14 operator action could be a really bad hair day. If 15 you know that ahead of time, does that, in some ways, 16 defeat the sort of warm feeling that you get because 17 everything is fine for 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br /> or seven days?
18 MR. NOLAN: So I think --
19 MEMBER BALLINGER: I mean, are we in a 20 situation here where -- this has got to be one of the 21 lessons learned, of course. But are we in a situation 22 where we're ignoring something because the rule says 23 in effect we do ignore it?
24 MR. NOLAN: No, I think the staff is in 25 agreement that there needs to be a safe means of NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.
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57 1 recovering the module. And this is something that I 2 believe Dr. Yarsky's white paper addresses is, how do 3 you use some of these systems to recover the module 4 and what are the potential impacts on safety? And so 5 the staff did addresses the use of those systems for 6 recovery. My point is it's just -- it's not within 7 the scope of Chapter 15.
8 MEMBER MARCH-LEUBA: Ryan, this is Jose.
9 I don't want to ambush you. And later or when they 10 allow me to do my comments, I wrote a white paper and 11 sent it up the chain that was supposed to make it to 12 you and apparently has not. I will give you this 13 later, but I believe that Dr. Yarsky's paper is off by 14 a factor of 5 in calculations. Whenever I'm allowed, 15 I will let you know why.
16 MR. NOLAN: Sure. Well, at the conclusion 17 of these questions for me, I believe I will be turning 18 it over to Dr. Yarsky. So that may be a good time to 19 bring it up.
20 MEMBER KIRCHNER: Yeah, let's put a pin in 21 that matter. Let's continue with the questions that 22 were first entered, Jose, and then we will provide 23 ample time for your concerns.
24 MEMBER PETTI: Well, can I ask a question?
25 MEMBER KIRCHNER: Go ahead, Dave.
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58 1 MEMBER PETTI: I'm just still a little 2 unclear. I understand Dr. Yarsky's paper and he's 3 really looking at events LOCA plus ATWS. But 4 inadvertent actuation of the ECCS is in AOO, and you 5 will deborate.
6 And basically, the staff has concluded 7 that out to, as Ron said, 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br /> or seven days, it's 8 okay, but it doesn't do anything. But afterwards if 9 the operator does something, it could be really bad, 10 although you concluded that it won't be bad based on 11 sort of a BD/BDA scenario, not sort of a Chapter 15 12 scenario. Is that correct?
13 MR. NOLAN: So I think -- because this is 14 just a design certification, we don't have the final 15 system design to do a full evaluation, nor the 16 procedures to understand how these systems will be 17 used. However, at this stage, conceptually, we 18 believe that the use of these systems can be -- they 19 can be safely used to recover the module from this 20 uneven boron distribution scenario.
21 MEMBER PETTI: At any time?
22 MR. NOLAN: Yes.
23 VICE CHAIR REMPE: Walt, can I ask --
24 MEMBER KIRCHNER: Yes, go ahead, Joy.
25 VICE CHAIR REMPE: I don't know if it's NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.
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59 1 redundant, but I have a question.
2 MEMBER KIRCHNER: Go ahead.
3 VICE CHAIR REMPE: Ryan, when you made 4 these conclusions and when I look through Peter's 5 paper in the last week or so, it seems like the 6 operators are going to rely on water level 7 measurements within the RPV to take such actions. And 8 I know the actions are coming later. But when you 9 think about those water level measurements in the 10 vessel could be off a couple of feet, plus or minus 11 feet, I mean, have you really thought about does the 12 operator have good information to make the judgments 13 required?
14 And I know it's a fuzzy line because they 15 don't have to do the procedures yet. But we said you 16 don't have to have as much rigor on and refined 17 accuracy with the water level in the core because we 18 didn't think the operators had to do anything. And 19 now we're back to, oh, the operators are going to need 20 to do something. Have you guys started to think about 21 that?
22 MR. NOLAN: So that's a really good 23 question, and that was one of the submitted questions 24 to the staff ahead of time. And we do plan on 25 addressing that. We plan on addressing it last. We NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.
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60 1 could probably answer now or we can wait until later.
2 VICE CHAIR REMPE: I can wait. Just when 3 I keep hearing, oh, the operators will take care of 4 it, I'm just going, with what? And so yeah, I'm very 5 interested in the answer to that question.
6 MR. NOLAN: So we planned on answering 7 this question a little later. Maybe you can hold off 8 till then.
9 VICE CHAIR REMPE: You bet.
10 MEMBER KIRCHNER: But Ryan, the 11 distinction I think that David Petti was trying to 12 make was he was -- we're talking about AOOs and design 13 basis events, including design basis accidents, all of 14 which are Chapter 15. We're not even considering yet 15 -- the Committee really wasn't considering LOCA plus 16 ATWS. Our concerns were just LOCA plus ECCS 17 actuation.
18 Let me ask you. I think I can say, but 19 the Committee members may correct me. I think in 20 general based on the presentations two weeks ago, we 21 would concur -- that's to be determined by Committee 22 -- that the holes that were put in the riser seemed to 23 ensure a continuing natural circulation and boron 24 redistribution, so to speak, for the decay heat 25 removal system passive cooldown events out to 72 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.
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61 1 hours1.157407e-5 days <br />2.777778e-4 hours <br />1.653439e-6 weeks <br />3.805e-7 months <br />.
2 And it appeared there that the figure of 3 merit that was used was the boron concentration, and 4 this is an average number because of the stylized 5 analyses that were simplified analyses that were used.
6 That the average concentration remained above the 7 critical boron concentration with some margin. And 8 beginning cycle, I'm doing this from memory, perhaps 9 almost 200 parts per million equivalent boron, middle 10 of cycle, on the order of 100.
11 So that provided reasonable confidence 12 that the downcomer hasn't diluted. But it seems like 13 now for the other end of the -- the other part of the 14 story which is post-ECCS that you're not using that 15 figure of merit. You're just -- if you will, you're 16 using a figure of merit. What's the boron 17 concentration in the core?
18 And I think we all would agree that the 19 boron concentration in the core is probably going to 20 be at the level at beginning of event, if not 21 increased through the course of the event. But again 22 going back to Member Ballinger's comment, it appears 23 that if you continue to dilute that downcomer, then 24 you put yourself in a position where any upset of the 25 status quo could result in a slug of deborated or less NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.
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62 1 borated water going into the core, displacing that 2 relatively high concentration of boron that's in the 3 core, and then leading to the potential for 4 recriticality, return to power, et cetera. So what 5 figures of merit are you using in your assessment to 6 say, this is okay out to 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br />?
7 MR. NOLAN: So the reason for the DHRS 8 cooldown and why we were concerned with the boron 9 concentration of the downcomer in relation to the 10 critical boron concentration is because ECCS will 11 eventually actuate. However, once ECCS actuates and 12 you do get this uneven distribution with the 13 concentrating boron in the core and diluted water 14 containment in the downcomer, there was no mechanism 15 in which we saw that would cause a large slug of 16 diluted water to enter the core. What we conclude is 17 that any water entering the downcomer is equal to the 18 boil off rate out the top of the riser. And in that 19 condition, our conclusion is that's a safe, stable 20 condition.
21 MEMBER KIRCHNER: Okay. I just wanted you 22 to clarify your position. I suspect that there are 23 members that don't think that's a safe, stable 24 condition. And --
25 MEMBER BLEY: This is Dennis again.
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63 1 MEMBER MARCH-LEUBA: We're suspicious of 2 it.
3 (Simultaneous speaking.)
4 MEMBER BLEY: Dennis Bley again. When you 5 went through your original answer, you cited the SECY.
6 And I wrote down 93-128. Did I get that wrong?
7 MR. NOLAN: No, that's correct.
8 MEMBER BLEY: I can no longer find that on 9 the public website, and I'm having trouble finding it 10 in ADAMS.
11 MR. NOLAN: I would just --
12 MEMBER BLEY: I would like to get that to 13 look at, please.
14 MR. NOLAN: Yeah, I usually just google 15 it, and it'll be, like, the first or second link.
16 MEMBER BLEY: Yeah, I did, and it isn't 17 there. Okay. Mike Snodderly, please get 93-128 for 18 us, if you're there.
19 MR. SNODDERLY: Yeah, if I could have some 20 help from the staff on that one. I'm like Ryan. I 21 googled it. And for some reason, I'm able to find it.
22 But yeah, that's how I normally access it.
23 MR. NOLAN: So here, I may have misspoke.
24 It's96-128. Sorry for that. I was just going off of 25 memory.
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64 1 MEMBER BLEY: Thanks.
2 MR. NOLAN: Yeah, and then there's an 3 associated SRM with that too. All I was trying to --
4 MEMBER BLEY: Okay.
5 MR. NOLAN: What I was trying to highlight 6 with that is other designs, we did a RTNSS review and 7 we did take a close look at the use of nonsafety 8 systems to continue core cooling functions. And I was 9 trying to just make the point that we did not do that 10 for NuScale because they've demonstrated that they can 11 get to seven days with just the use of the automatic 12 safety-related systems.
13 MEMBER MARCH-LEUBA: Yeah, this is Jose.
14 Just so we understand, I think our concerns and then 15 my concern is if you are in a continuously degrading 16 condition, eventually, you're going to have to recover 17 from it. And eventually, you're going to have to 18 transfer the module to Mode 4 which is the one that 19 allows you to transport it to the refueling station to 20 fix it if something went wrong, right? And that is 21 something that will be addressed.
22 How specifically step one, two, three, 23 four, five is done will be addressed by the COL? I 24 just don't see a credible mechanism with some 25 definitive, scientific backup that says you can do NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.
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65 1 that. You base your statement that there is no 2 credible mechanism to insert those 15 to 20 cubic 3 meters of deborated water that's sitting in front of 4 the core, and you're basing it on Dr. Yarsky's paper.
5 I'm sure. I mean, we received it one 6 afternoon before our final meeting. And I had time to 7 review it now, and I see some issues with it. So I 8 just don't think that this is scientific and thorough, 9 just to believe that nothing will happen. It's not 10 good to me -- not good for me.
11 I don't want the procedure. I want you to 12 tell me if I turn this valve and I start putting flow 13 through this, I will recover safely. And the only 14 argument I get and I agree with Dr. Yarsky is that 15 we're mixing in the upper plenum. But Jesus, I need 16 better calculation that somebody has calculated. And 17 we'll go into details later on when it's my turn.
18 MEMBER KIRCHNER: Thanks, Jose. Ryan, 19 let's continue on with the questions at this point so 20 we can go through those first, and then we'll turn to 21 members.
22 MR. NOLAN: Yeah, I think I'm going to 23 turn it over, I believe, to Dr. Yarsky --
24 (Simultaneous speaking.)
25 MEMBER KIRCHNER: Okay.
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66 1 MR. NOLAN: -- to then go through the rest 2 of these questions or to start going through the rest 3 of the questions.
4 MEMBER KIRCHNER: Okay, good. Peter, 5 you're on.
6 MR. YARSKY: Hello. This is Dr. Peter 7 Yarsky from the research staff. And I wanted to take 8 the time to respond to General Questions A, B, and D 9 from the questions that we received. The first 10 question, Question A, was focused on what seems to be 11 the main point of contention and is related to 12 reactivity insertion rate.
13 And so research developed a written 14 technical evaluation report to respond to these 15 questions. I'm not sure if there was the opportunity 16 for that to be provided to the Committee in advance.
17 But I wanted to give at least a high level overview of 18 the --
19 MR. SNODDERLY: Peter, this is Mike 20 Snodderly. If I could just interrupt you for a second 21 because I think that's a very important point. I just 22 want to make sure we're all on the same page. So 23 there is what I'm going to call the Peter Yarsky 24 Report 1 which was in response to the NRR Request 0-14 25 and that is ML20191A069, dated July 1st, 2020. And NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.
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67 1 that is --
2 MEMBER MARCH-LEUBA: Can you read us --
3 MR. SNODDERLY: -- publicly available --
4 MEMBER MARCH-LEUBA: Can you read us a 5 title? Do I have it?
6 MR. SNODDERLY: Yes, yes. That's --
7 (Simultaneous speaking.)
8 MR. SNODDERLY: -- the one that everyone 9 has. And I'm also trying to benefit for the people 10 from the public to understand what we're talking about 11 now. And so that is the first Yarsky report dated 12 July 1st. That's the one we've all looked at during 13 the June 3rd and 4th meeting, and it is publicly 14 available. We can --
15 MEMBER MARCH-LEUBA: Is this the one that 16 we referenced as the white paper and is --
17 MR. SNODDERLY: Yes.
18 MEMBER MARCH-LEUBA: -- marked proprietary 19 ECI?
20 MR. SNODDERLY: Yes, and there is now a 21 publicly available version, and I just read that ML 22 number. And that's the publicly available one, and 23 that's one that we can reference as part of our 24 deliberations here.
25 MEMBER MARCH-LEUBA: So the proprietary NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.
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68 1 ECI markings have been removed from the one I have.
2 MR. SNODDERLY: No, no, no, no. There's 3 a proprietary ECI version that you have, and you need 4 to continue to treat that. I'm just saying there's 5 another redacted version that I didn't give you 6 because you're not as interested in the public 7 version. But the public is, and that's the number I 8 just read.
9 MEMBER MARCH-LEUBA: It would be --
10 MR. SNODDERLY: And that's what we were 11 referencing --
12 MEMBER MARCH-LEUBA: I would be nice to 13 have had it because I know what I can talk about and 14 what I cannot talk about. But okay, go ahead.
15 MR. SNODDERLY: Okay. So that's the 16 document that we can reference in your boron 17 distribution letter that we're going to talk about 18 later this afternoon. Now Dr. Yarsky has written a 19 second paper in response to a second request from the 20 staff, 0-15, that is proprietary and it has not been 21 reviewed by NuScale. So there is not a publicly 22 redacted document yet.
23 And so I don't know if there'll be one in 24 time so that the Committee can refer to this. Right 25 now, I don't think we can plan for that unless we get NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.
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69 1 some kind of commitment from NuScale and the staff 2 that it will be. Otherwise, you were in the same 3 predicament as the Chapter 1 FSAR which we have a 4 solution path now for as a result of the commitment by 5 the staff.
6 MEMBER MARCH-LEUBA: Mike, do I have that 7 document?
8 MEMBER KIRCHNER: Does the entire 9 Committee have that document?
10 MR. SNODDERLY: No, no.
11 MEMBER KIRCHNER: Does anyone have it?
12 (Simultaneous speaking.)
13 MEMBER KIRCHNER: I know a document of 14 viewgraphs, but --
15 MR. SNODDERLY: Right, that's what we have 16 and we could go into closed session to talk about.
17 What I'm trying -- what I would like the Committee to 18 make sure they understand is if they do want to refer 19 to this other paper, there are some logistical 20 problems as far as timing. So do you really want to 21 see this additional information, or do you just want 22 to discuss it in public session with Dr. Yarsky and 23 then it's on the record? But if we go --
24 MEMBER MARCH-LEUBA: Last time I checked 25 --
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70 1 MR. SNODDERLY: -- to the first --
2 MEMBER MARCH-LEUBA: Last time I checked, 3 ACRS has access to all proprietary ECI information.
4 We may not be able to reference it in an open letter, 5 but we should have access to the information.
6 MR. SNODDERLY: Well, so it is now 7 available, and I shared the viewgraphs with you Walt 8 --
9 MEMBER MARCH-LEUBA: I see the viewgraphs.
10 MR. SNODDERLY: -- yesterday to determine 11 whether you want to pursue further this document. I 12 caution you because I don't think it's going to be 13 part of the record so that you can reference this for 14 this letter that you plan to write in the next day or 15 two.
16 MEMBER MARCH-LEUBA: So --
17 MR. SNODDERLY: That's all I'm saying.
18 MEMBER MARCH-LEUBA: -- let me see if I 19 understand correctly. The staff is asking us to write 20 a letter on an SDA we have never seen and make 21 judgments on the quality of the technical content of 22 a document that was created yesterday and we have 23 never seen.
24 (Simultaneous speaking.)
25 MR. SNODDERLY: I would say it a little NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.
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71 1 different, Jose. The staff has additional information 2 that the Committee may consider. But right now, it is 3 still proprietary and it has not undergone proprietary 4 view yet by NuScale.
5 MEMBER MARCH-LEUBA: I think --
6 MR. SNODDERLY: They can tell us where 7 that is in process.
8 MEMBER MARCH-LEUBA: I think I placed my 9 concerns on the record that this is not proper 10 procedure.
11 MR. SNODDERLY: It's --
12 VICE CHAIR REMPE: Mike --
13 MR. SNODDERLY: -- late in the process.
14 MEMBER PETTI: Mike, this is Dave.
15 VICE CHAIR REMPE: Please share --
16 MEMBER PETTI: I just can't --
17 VICE CHAIR REMPE: -- the graphs in the 18 document with all of us.
19 MEMBER PETTI: Yeah, I just can't -- given 20 the magnitude of what this letter is about, we need 21 all information, proprietary, not proprietary. We're 22 talking about probably the most important letter we 23 have to write on NuScale, and I feel like I've got it 24 tied behind my back now because you told me there's 25 some new information that we're hearing only today.
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72 1 So I recommend --
2 (Simultaneous speaking.)
3 MEMBER RICCARDELLA: Can't we go into 4 closed session and review the -- and go through those 5 viewgraphs?
6 MEMBER KIRCHNER: I think that's what we 7 need to do, Pete.
8 MEMBER MARCH-LEUBA: Pete, I would 9 strongly recommend against it because I still have 10 some items that have been placed on the open record.
11 (Simultaneous speaking.)
12 MEMBER KIRCHNER: No, no. We will let you 13 do that, Jose. We're not proposing to, in any way, 14 prevent you from putting something on the record.
15 What I'm just agreeing with Pete is -- and Mike 16 Snodderly, I think what we would want is an ask of the 17 staff for Peter Yarsky to go through. The viewgraphs 18 that were provided late last night, I believe, are a 19 summary of what you're identifying as the second white 20 paper. Do you I understand this correctly?
21 MR. SNODDERLY: That's correct, sir. That 22 is correct, sir.
23 MEMBER KIRCHNER: So let us ask for the 24 staff, Peter Yarsky, to present those viewgraphs in a 25 closed session. I think we have to do that at this NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.
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73 1 juncture. But let's --
2 MR. SNODDERLY: I would suggest --
3 MEMBER KIRCHNER: -- finish the questions.
4 MR. SNODDERLY: -- before you do that, for 5 the benefit of the public, though, I think it would be 6 helpful for Dr. Yarsky in public session to provide 7 some description --
8 MEMBER KIRCHNER: Yes, a summary 9 description of the report.
10 MR. SNODDERLY: -- what he did, why he did 11 it, and what confidence it gives him now in his 12 previous conclusions in papers because my 13 understanding is the staff asked for this support 14 because they wanted more certainty. And so if he 15 feels that this gave him more certainty, he should be 16 able to describe in general terms what he did and why 17 it gives him more certainty. And then we can go into 18 closed session for a more detailed discussion.
19 (Simultaneous speaking.)
20 MEMBER KIRCHNER: We can ask him to do 21 that. Let's finish. Dr. Yarsky had started on the 22 questions. Let's do that. I think we're agreed now 23 on further steps and what we would do in closed 24 session, and we can ask Dr. Yarsky to just summarize 25 for the public what these two papers contain.
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74 1 VICE CHAIR REMPE: Walt, while we're going 2 through the rest of the open session, may we request 3 that Mike Snodderly provide that information to us and 4 in an appropriate location on the SharePoint site and 5 send us an email and let us know where that 6 information is, the white paper and phase two of the 7 paper and the viewgraphs now.
8 MR. SNODDERLY: I do not have --
9 MEMBER KIRCHNER: Just --
10 MR. SNODDERLY: I do not have the second 11 paper. I have some slides that I asked the main 12 members to make a recommendation of whether it should 13 be considered further as part of the record. I do not 14 think it will be available in time, and that's why I 15 was suggesting that we not consider as part of your 16 deliberations.
17 I do not have the paper. I have the 18 slides that we agreed with the staff that if they 19 decide they want to use them as backups -- right now, 20 they're backup slides. Once they present them, then 21 they'll be part of the record and I will share them 22 with the Committee.
23 VICE CHAIR REMPE: Why can't -- if you've 24 shared it with two members, please share the slides 25 with all the members now, please.
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75 1 MR. SNODDERLY: After the staff says that 2 they will put those slides on the record, then yes, I 3 will share them with all the Committee.
4 VICE CHAIR REMPE: This is not the normal 5 way we do business.
6 MR. SNODDERLY: I ask that you appreciate 7 the time constraint that I've been put under and then 8 I tried to do the best I can to share this 9 information.
10 MEMBER KIRCHNER: No, we appreciate that, 11 Mike. Okay. Joy, I will ask -- I'm asking formally 12 of the staff please provide the viewgraphs to all the 13 members on their NRC email -- at their NRC email 14 address, not SharePoint.
15 MR. SNODDERLY: Okay. So we are going to 16 then go into closed session and put these slides --
17 MEMBER KIRCHNER: Yes.
18 MR. SNODDERLY: -- then on the record as 19 proprietary documents. I understand --
20 MEMBER KIRCHNER: Yes.
21 MR. SNODDERLY: -- and I will do so. And 22 I will --
23 (Simultaneous speaking.)
24 MEMBER KIRCHNER: Yeah, thank you, 25 Michael. That's fine.
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76 1 MR. SNODDERLY: Okay.
2 MEMBER KIRCHNER: Just so --
3 MR. YARSKY: And Mike, Peter Yarsky from 4 the staff. I just wanted to clarify that of the slide 5 package, we had marked two of the slides as 6 proprietary. But they are not proprietary as of 2015.
7 So that was a mistake on the part of the staff. None 8 of the slides contain proprietary information.
9 MR. SNODDERLY: Oh, fantastic. Then I'd 10 ask you to --
11 (Simultaneous speaking.)
12 MR. SNODDERLY: Then let's go to the 13 slides, and then they're on the record and everybody 14 has them.
15 MR. BAVOL: Mike, this is Bruce Bavol.
16 MR. SNODDERLY: Yes.
17 MR. BAVOL: To be clear, NuScale has not 18 reviewed any of that information for proprietary 19 because we got it yesterday afternoon.
20 MR. SNODDERLY: That's my understanding.
21 MR. BAVOL: Yes, so I mean --
22 MR. SNODDERLY: And I'm sorry if I didn't 23 say that clearly. But yes, that was my understanding.
24 MR. BAVOL: That's staff's input, and I 25 appreciate -- and it's most likely correct. Just we NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.
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77 1 haven't verified it through NuScale that any of those 2 slides do not contain proprietary information.
3 (Simultaneous speaking.)
4 MR. MOORE: So this is Scott Moore.
5 Bruce, can you expedite your review so that if it is 6 not proprietary, we could get it on the record as soon 7 as possible?
8 MR. BAVOL: I will -- yes, I mean, this is 9 an arrangement that we were talking about yesterday.
10 But I'll pursue that, Scott.
11 MR. MOORE: Thank you. And just for all 12 of the members, I'd remind everybody that the staff 13 has been getting documents at, like, 10:00 o'clock at 14 night and being asked to distribute them. So the 15 staff is doing its best to get you all documents.
16 MEMBER MARCH-LEUBA: Hey, Scott. This is 17 Jose. I recognize you are under a big constraint. I 18 mean, you're put in a real bad position. But they're 19 asking us to write a letter, ACRS, a distinguished 20 body even though I belong to it, by Friday. And I 21 just don't see how I can support that when information 22 keeps coming up that we cannot see.
23 MR. MOORE: The staff will make 24 information available the Committee as a whole 25 requests. And once on the record, we will provide you NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.
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78 1 with the information you need to make decisions by 2 Friday.
3 MEMBER KIRCHNER: But I think -- yeah, 4 without going into great detail on this, I think we 5 can go into closed session and we can have those 6 viewgraphs presented to us in closed session. And I 7 think for the public record, we can make it clear, at 8 least in a general way, what the content is while we 9 wait for a review from NuScale and a determination as 10 to whether they can contain proprietary information 11 and whether they can then be posted on open. But that 12 doesn't stop us from going into closed session and 13 considering the viewgraphs.
14 MEMBER MARCH-LEUBA: Walt, can I make a 15 suggestion?
16 MEMBER KIRCHNER: Yes.
17 MEMBER MARCH-LEUBA: I've read the slides, 18 and you remember two weeks ago I was saying to 19 everybody that you were misquoting Dr. Yarsky. Dr.
20 Yarsky in those slides has a novel theory of why the 21 front does not become a problem of reactivity 22 insertion in the core. And it's not the same theory 23 that is reflected on the SER.
24 And the paragraph that I want to point out 25 some mistakes in the calculation. So if we could hear NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.
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79 1 in the open session from Dr. Yarsky was a series of 2 why this 15 to 20 cubic meters of deborated water in 3 the lower plenum, downcomer, and containment coming 4 into the core do not cause a problem. It would be --
5 I think his theory is not NuScale's theory. I think 6 it would be valuable to do it in open session because 7 these are something completely different.
8 MEMBER KIRCHNER: Okay.
9 MEMBER MARCH-LEUBA: And I know what he 10 said.
11 MEMBER KIRCHNER: So with that, we 12 interrupted Dr. Yarsky. Peter, would you like to 13 venture and continue?
14 MR. YARSKY: Yes, Walt. Thank you. I 15 would like to continue in open session because I 16 believe that 100 percent of the information I'd like 17 to discuss in response to these questions is 18 appropriate for the public session.
19 MEMBER KIRCHNER: Good. That's to be 20 welcomed. Thank you.
21 MR. YARSKY: Okay. So in response to 22 Question A, this we're referring to as the main point 23 of contention issue. I think it needs a little bit of 24 clarification, and I do appreciate Jose's comment with 25 regards to interpretation of the staff position as NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.
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80 1 presented in the previous white paper. And I would 2 like to take this opportunity to hopefully clarify 3 some of that rationale.
4 First, this was something that was not 5 done in the original white paper. But I think it is 6 valuable to try and think about possible mechanisms of 7 what we've referred to as flow incursion that could 8 transport deborated water from the downcomer into the 9 core as falling into one of two categories. The first 10 of these categories we could consider as like a 11 transient mechanism.
12 An example of a transient mechanism would 13 be if the ECCS were to -- if the ECCS valves were to 14 open, this would create a level swell followed by 15 flush that in a transient short-term way would create 16 sort of a flow pulse and that after that initiation 17 and that short transient, the driving force that's 18 propelling the transport of the fluid goes away. So 19 it's like a transient mechanism. These tend to be 20 more rapid, and there's sort of a sudden movement of 21 fluid and then it doesn't continue.
22 The second type of mechanism or second 23 category rather of mechanisms I think we would call a 24 prolonged mechanism. And this would be something more 25 akin to a recovery type operation where, for instance, NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.
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81 1 CVCS or CFDS is put into an injection mode in order to 2 raise water level. And in that kind of scenario, that 3 continuous injection is providing a prolonged core 4 flow increase that is sustained over a long period of 5 time.
6 And so for these more prolonged 7 mechanisms, the staff went about calculating the 8 reactivity insertion rate. And I believe that this 9 has led to some confusion. For a hypothetical manual 10 operator action to increase level in this prolonged 11 mechanism, that can lead to the transfer of deborated 12 or low concentration water from the downcomer into the 13 core. And that would progress at different rates 14 depending on what systems are being used to provide 15 that injection.
16 And we calculated for a completely 17 deborated downcomer what that reactivity insertion 18 rate would be. However, we do not believe that that 19 rate is indicative of a continuous accumulation of 20 reactivity at that rate. We wanted to calculate that 21 rate in order to get an idea of just the timing of the 22 dynamic process, to get an idea of what the time scale 23 was for -- is this something that is a very rapid 24 process, or is this a very slow process?
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82 1 compare that timing to what would be the mixing time 2 in the core region. And so ultimately, I believe, the 3 main point of contention relates to whether or not 4 there are physical processes or phenomena that would 5 lead to the mixing of the low concentration downcomer 6 water that's being moved into the core region and the 7 high boron concentration water that's in the core 8 riser region.
9 And so with these prolonged mechanisms in 10 mind, if it takes a very long time to insert a 11 dollar's worth of reactivity according to how we 12 calculated that rate and that amount of time is much 13 longer than the amount of time it would take for the 14 inventory to mix. Then we contend that the reactivity 15 doesn't accumulate. That mixing process sort of takes 16 the reactivity out of the deborated water by restoring 17 high boron concentration in the core average, more 18 homogeneous inventory in the active region.
19 And so I hope that that partially 20 clarifies the staff's position about the importance of 21 phenomena relative to the time scale. So I wanted to 22 pause and ask if there was, like, any questions 23 relative to that clarification because I would like to 24 discuss more afterwards about what this -- what 25 generates the mixing phenomena and what the evidence NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.
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83 1 is that such mixing would take place.
2 MEMBER MARCH-LEUBA: Mr. Chairman, I think 3 this is a perfect opening for my complaints about 4 Pete's calculation, and I would like to go ahead and 5 do it. Okay? Pete --
6 MEMBER KIRCHNER: Dr. Yarsky, are you 7 amenable to an interruption here so that Member March-8 Leuba can enter into the record his concerns?
9 MR. YARSKY: Of course. I think I paused 10 for such an interruption.
11 MEMBER KIRCHNER: Yeah, okay. Thank you, 12 Peter. That's a good summary. I believe that that's 13 a good summary of the state of affairs in terms of 14 what the Committee is concerned about. So with that, 15 I'll turn to Member March-Leuba.
16 MEMBER MARCH-LEUBA: Okay. So I am going 17 to read from the open SER Section 19.1.4.6.3 called 18 reactor building -- oops, sorry. I went up too far.
19 19.1.4.6.4, success criteria accident sequences and 20 system analysis.
21 In this section, the staff of the SER --
22 the final SER, the staff quotes, a calculation, which 23 we will attribute to Dr. Yarsky, in which he says or 24 they say that the maximum reactivity insertion is 25 approximately 29 dollars. And that's how we calculate NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.
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84 1 this PRAM rate that you hear me say a lot two weeks 2 ago at one dollar per minute. This 29 dollars are 3 calculated by assuming that the boron concentration in 4 the core is the initial BOC concentration which is 5 1,250 ppm.
6 And then the SER uses a linear 7 approximation with a boron coefficient of 14 PCS per 8 ppm. I'd rather use 10 because I know it's nonlinear 9 and it's -- so parenthesis, this is an approximation.
10 This is a linear approximation that the real numbers 11 will differ when you do the real calculation.
12 But this 29 dollars are assuming the 13 deborated water in the lower plenum displaces 1,250 14 ppm borated water in the core. But we know by now 15 from RAI-8930 that the concentration in the core at 16 this time, we're talking, say, 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br /> after the 17 initiation of the transient. The boron concentration 18 at this time is at least 4,000, and the staff have 19 told us -- not staff. The applicant has told us 20 orally that if you do it more from an estimate, it 21 could be as high as 6,000. So it's not 1,250. It's 22 6,000.
23 If you use the same calculation the staff 24 used for this paragraph on Chapter 19, instead of 29 25 dollars, I calculate the perturbation is closer to 140 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.
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85 1 to 150 dollars. And in units that Charlie Brown would 2 understand, he doesn't like dollars, this is a delta 3 K over K of 0.6. And I'm not talking 0.6 percent.
4 I'm talking 60 percent, delta K over K of 0.6. This 5 is an incredibly high perturbation.
6 If you are displacing 6,000 ppm borated 7 water from the core with the front that moves in, you 8 are not having a one dollar per minute reactivity.
9 You're have a five dollar per minute reactivity. And 10 reality, this assumes that the front is flat like 11 water and oil. It's uniform and it's moving slowly.
12 But we all know that the center of the core will have 13 a higher flow.
14 So your front would be more like a 15 parabola or maybe a sine wave with lows on the 16 outside. But the water -- the volume -- the 17 volumetric rate of deborated water into the core will 18 go mostly in the center of the core. It's the one 19 that has the high reactivity worth. And it likely not 20 be five dollars per minute. It'll be probably six, 21 seven, eight dollars per minute when you do the proper 22 weighting.
23 So the argument that the SER makes that 24 one dollar per minute is such a slow rate, I never 25 believe I'd say that one dollar per minute is a slow NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.
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86 1 rate. But it's slow enough that you will be at 2 thermal equilibrium. It doesn't hold water when you 3 actually make a back-of-the-envelope calculation with 4 a real concentration of boron.
5 And you're having now five, six, seven, 6 eight dollars per minute. And now you are close to 7 the fuel thermal constant. So number one, the SER 8 numbers in this section, I said it before, they're 9 incorrect. They need to be corrected.
10 MEMBER KIRCHNER: Hey, I would -- Jose, 11 since we're on the open record, I would say the 12 following. I would say that the estimates in the SER 13 certainly could be subject to question and 14 interpretation. I would submit that in your scenario, 15 one of the problems is that the rather stylized, 16 simplistic boron concentration estimates I do not 17 think would reflect what a best estimate calculation 18 would provide.
19 And by that, what I mean is you would not 20 have a 4,000 or a 6,000 dollar -- 6,000 ppm 21 concentration. It would be much less because it would 22 be spread through the lower plenum and the downcomer.
23 If you really took mixing into account, you wouldn't 24 have this stylized, static buildup of all the boron 25 only in the core and the riser. That is just not NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.
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87 1 physically possible.
2 So I would say that -- I would not say 3 that their estimates are incorrect or in error. I 4 would say that one could postulate as you do a static 5 worth that bounding would be a much higher rate of 6 reactivity insertion.
7 MEMBER MARCH-LEUBA: Okay. And with that 8 --
9 MEMBER KIRCHNER: But --
10 MEMBER MARCH-LEUBA: With that rude 11 interruption, may I beg you to let me finish?
12 (Simultaneous speaking.)
13 MEMBER MARCH-LEUBA: And so I will not 14 answer to your comment until after I finish. Okay.
15 So in my opinion and given the only calculations I 16 have on record from the applicant tell me that they 17 have at least 4,000 ppm of boron. You cannot assume 18 1,250. It will not possibly be 1,250.
19 So let's go back. So the perturbation is 20 going to be up to 140, 150, likely much lower when you 21 consider nonlinearities. And the core will be very 22 subcritical when you start. Okay. That's not 23 important to the run rate. The run rate is at which 24 velocity do you displace boron from the core. And 25 you're displacing boron from the core in my estimate NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.
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88 1 at five, six, seven, eight dollars per minute.
2 Furthermore, once you reach K effective 3 equal one which if you have 6,000 ppm overall will be 4 late of course. Once you reach K effective of one, 5 you will return to power and you will start generating 6 voids in the riser. And Dr. Yarsky's paper properly 7 identifies the only thing that can get in trouble with 8 ingress of water honestly is reestablishing that 9 circulation. Any other sort of injection is very 10 slow.
11 So if you regain power and the core riser 12 void fraction becomes close to 50 percent by 13 eyeballing some of the drawings we have in the 14 documentation, the riser -- the two phase flow level 15 in the riser will go over the top of the riser and 16 will start overflowing. And that circulation will 17 start occurring. And that circulation is a fast 18 mechanism to inject cold unborated water. So if you 19 -- this slow ingress ever gets you into a K effective 20 of one and a little bit more so you have power of 21 five, ten percent which was required for 50 percent 22 voids, you will get a positive flow feedback that 23 would put a lot more cold unborated water into the 24 core and you will run out.
25 MEMBER KIRCHNER: Jose, may I interrupt?
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89 1 MEMBER MARCH-LEUBA: No.
2 MEMBER KIRCHNER: Okay. Well, you are 3 good at interrupting. I thought you would be --
4 MEMBER MARCH-LEUBA: Walt --
5 MEMBER KIRCHNER: -- a little more 6 flexible.
7 MEMBER MARCH-LEUBA: Walt, Walt, Walt, 8 please. You've never listened to me. Okay. Let me 9 do the --
10 MEMBER KIRCHNER: I do listen very well to 11 you.
12 MEMBER MARCH-LEUBA: No, you don't. No, 13 you don't. Okay. So I've described two problems with 14 what we have on the books. First, the run rate is not 15 one dollar per minute. It has to be greater.
16 Second, if the SER says, well, without run 17 rate, we'll eventually reach criticality. But we will 18 be in thermal equilibrium with the fuel and with some 19 feedback and we will still satisfy SAFDL. Fine. But 20 if you can get the power high enough to get 50 percent 21 voids, you will get a positive flow feedback that will 22 put a lot of water into the core. This mechanism was 23 not identified by the staff or the applicant as one 24 possible source of borated water -- of unborated water 25 into the core.
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90 1 Number three, when I run the calculations 2 in my head and I don't have MCMP -- I do have MCMP, 3 but I don't have a MCMP model. I have a MCMP license.
4 When I write in my head, the void reactivity 5 coefficient of a highly heterogeneous core which has 6 clean water and 6,000 ppm water is almost sure 7 positive. So the moment you get to K effective equal 8 one, my head calculations tell me that you won't even 9 have to restart that circulation. You will get into 10 a positive feedback that will run away the reactor.
11 So I have three different arguments why 12 this is not a safe solution. And I'm not saying that 13 when we run MCMP and TRACE or a good model, you can 14 actually prove that good things happen. It may, but 15 I don't see anybody addressing those three different 16 problems, and I just cannot support this. Okay, Walt.
17 Now you can start throwing rocks at me.
18 MEMBER KIRCHNER: No, no, no. You 19 wouldn't even let me agree with you on anything. So 20 first, I guess I would observe, Jose, a few things.
21 I actually agree with you on the concern about the 22 reactivity rate.
23 I do personally believe that you will get 24 mixing. This idea of just a uniform front slowly 25 progressing into the core defies -- well, you'll get NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.
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91 1 mixing in a system like this. It's something that 2 should be analyzed. I think it works to mitigate the 3 ramp rate and such.
4 Second, I am with you. I am concerned if 5 you return to power and you start generating any kind 6 of void, there's the distinct possibility of just 7 having a geyser-like effect. Now depending on the 8 amount of void as you point out, one of the things Dr.
9 Yarsky pointed out in his first white paper which was 10 one my biggest takeaways at a technical level is for 11 the public, we talk about when you have high 12 concentrations of boron, essentially this creates --
13 it's like having a black absorber of neutrons.
14 So at these very, very high concentrations 15 which I don't think will actually occur in the actual 16 system because of mixing throughout the system, 17 essentially the upper part of the core as it's 18 displaced, if it's displaced slowly, will basically 19 remain black until, as Jose points out, if you did 20 return to critical and you started generating voids, 21 then you have a concern because you could push up on 22 the riser. If you have enough void, it could spill 23 over. I don't think the spillover, Jose, 24 reestablished natural circulation.
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92 1 to have an actual natural circulation reestablished.
2 You need to have both levels at the riser level to 3 have a full reestablishment of natural circulation.
4 But I do agree with you that if you have a swell that 5 that could lead to a power excursion. And that could 6 -- the void formation could spill over, and that would 7 drive more water from the downcomer lower plenum into 8 the core.
9 So one then -- because it's now at a low 10 pressure, because we're post-ECCS in the scenarios 11 that we're very concerned about, there is the 12 possibility of the system going through an oscillatory 13 mode. This is why we don't operate BWRs at low 14 pressure, for example, because of the void feedback 15 effects. And I agree with you. If the voids get high 16 enough in that very black core section, then you have 17 an amplification potential.
18 But I would remind everyone that we're 19 using -- because we're doing heuristic arguments in 20 our head, we're using static worths. And this is a 21 dynamic problem. And the kinetic feedback effects, 22 the first order, it's an undermoderated core.
23 If you did have that front come in, the 24 general feedback, as long as the upper part of the 25 core remains in a black configuration is going to be NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.
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93 1 -- how should I say it? It will be in a negative 2 direction. In other words, it will kind of self-3 regulate the power excursion. But still there's the 4 possibility then that you have manometer oscillations 5 as a result of the first incursion.
6 So the bottom line for me remains one of 7 preventing that lower plenum and downcomer boron 8 concentration from falling below the critical boron 9 concentration. And it's not apparent to me, and I 10 would ask Dr. Yarsky if he's looked at this. I think 11 he has a viewgraph that looks at different time 12 scenarios.
13 But it's not apparent to me that that 14 critical boron concentration doesn't fall -- I'm 15 sorry, that the downcomer concentration doesn't fall 16 below the critical boron concentration, I think in a 17 time that's measured in maybe just a couple or a few 18 hours2.083333e-4 days <br />0.005 hours <br />2.97619e-5 weeks <br />6.849e-6 months <br />, not 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br /> for some of the small break LOCA 19 transients that were examined. So Jose, I'm trying to 20 agree with you.
21 MEMBER MARCH-LEUBA: Okay. Thank you for 22 agreeing, but let me summarize what I said. The SER 23 -- the staff SER has a blanket statement that says, we 24 have evaluated thoroughly all possible mechanisms for 25 what Dr. Yarsky called a slow water ingression by NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.
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94 1 operator action into the core. And none of them can 2 cause severe core damage.
3 I have three arguments that need to be 4 addressed before that statement can be substantiated.
5 Number one, the ramp is now one dollar per minute, but 6 it's maybe five, six, seven, eight. Number two, the 7 void coefficient -- void reactivity coefficient may be 8 positive. I haven't seen a calculation that it's not.
9 And number three, if you return to power 10 and you start spilling over the top of the riser, you 11 accelerate the rate of ingression of the cold water.
12 So there are three mechanisms I can think of that have 13 not been addressed to confirm the statement on the 14 SER. Walt, would you allow me another two minutes?
15 MEMBER KIRCHNER: Yes, go ahead.
16 MR. YARSKY: Jose, would the staff have an 17 opportunity to respond to those three items?
18 (Simultaneous speaking.)
19 MEMBER MARCH-LEUBA: Yes --
20 (Simultaneous speaking.)
21 MEMBER KIRCHNER: Yes, of course Dr.
22 Yarsky.
23 MEMBER MARCH-LEUBA: Let me -- let me 24 finish with one thought. I agree with -- with Dr.
25 Yarsky that this is not likely to happen because he NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.
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95 1 thinks mixing will occur. Let me put it in pre-2 kindergarten level, okay? So that the people that --
3 the members of the public that can -- reading this 4 transcript can understand it. What Dr. Yarsky is 5 saying is that water from the longer plenum, which is 6 deborated, we move through the core with criticality.
7 We go through the upper plenum, mixed with all the 8 boron -- there are lots -- amount of boron that have 9 accumulated in the -- in the riser -- and then come 10 down and get into the core with a proper boron 11 concentration so it will not cause a criticality.
12 So when Dr. Yarsky says mixing, what he 13 means is the lower plenum and downcomer mixes with the 14 riser without causing a criticality as it goes to the 15 core. Yes, Dr. --
16 (Simultaneous speaking.)
17 MEMBER KIRCHNER: Jose, we should let Dr.
18 Yarsky give his scenario. But before then, I -- when 19 I was talking about mixing, I am not talking the 20 riser. I am talking about mixing in the lower plenum 21 to begin with -- and the downcomer. It's incredible 22 to postulate that there's no boron in the lower plenum 23 or the lower downcomer. Secondly, it's only a result 24 of a stylized set of assumptions and analysis with 25 only three nodes, if I remember correctly. Secondly, NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.
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96 1 the mixing I am more concerned about -- I -- even if 2 the core and the upper riser are thoroughly mixed --
3 which they probably are because of the thermal 4 conditions and delta Ts in -- in that part of the 5 system -- it's immaterial. It's essentially a black 6 core, whether it's 2,000 -- 4,000 or 6,000 PPM.
7 The mixing I am talking about is the 8 mixing as you come through the lower core support 9 plate and into the core. And that's the critical 10 issue in my mind because that's -- that's where you're 11 going to prevent the initial criticality.
12 MEMBER MARCH-LEUBA: The initial one, yes.
13 But you have to remember that you have 15 to 20 cubic 14 meters of deborated water. When I say deborated 15 water, it's like --
16 (Simultaneous speaking.)
17 MEMBER KIRCHNER: But you have to -- you 18 have to postulate a mechanism, as Dr. Yarsky points 19 out, to rapidly insert that amount of water. And you 20 -- we haven't been able to do that. I can think of 21 some scenarios that will give a -- a nudge to the 22 system, like injecting CVCS, cold water in the upper 23 riser. That will certainly induce a flow. But when 24 you say that this 15 core volumes are -- are there, 25 there's no plausible mechanism, particularly coming NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.
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97 1 out of the containment, to get that water into the 2 core in a rapid manner as Dr. Yarsky divided the --
3 the problem.
4 (Simultaneous speaking.)
5 MEMBER MARCH-LEUBA: It doesn't -- it 6 doesn't need to be rapid -- as we know, it takes 7 roughly a minute for -- for a whole core volume to be 8 replaced with the other water. But if it mixes, it 9 comes in, you will get more deborated water that 10 follows. You have 15- to 20-cubic meters of deborated 11 water. And when I said deborated, I mean 100 PPM, or 12 low-borated -- because there will always some 13 volatility and some concentration. But certainly not 14 above the CVC.
15 So if you mix the first round that comes 16 in with the core, you will change the core -- and the 17 core concentration now will be half of what it used to 18 be. As the next one comes on -- because there is 14 19 of them -- you will go half again. You will be 25 20 percent. And then it will 12.5 percent, and then six 21 percent -- and eventually you'd want to go critical.
22 It leaves so much water following the train --
23 (Simultaneous speaking.)
24 MEMBER KIRCHNER: Yes, but you have to 25 mechanism to get it into the core. I think that's --
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98 1 that --
2 (Simultaneous speaking.)
3 MEMBER KIRCHNER: -- that's another 4 simplistic assumption, Jose, that -- that -- you know, 5 sometimes I would -- I would point out that when we 6 make these kind of bounding analyses, we actually 7 aren't necessarily getting a conservative result.
8 (Simultaneous speaking.)
9 PARTICIPANT: -- can you entertain 10 somebody else --
11 PARTICIPANT: Yes, yes. Yes, yes -- I 12 heard both Dennis and I think I heard David Petty. Go 13 ahead, Dennis.
14 MEMBER BLEY: Okay, I -- I would just like 15 to say a couple of things because I am not sure we're 16 making progress here. I -- I -- three or four things.
17 I'll start with what Peter told us earlier. I really 18 appreciate your physical description when -- that's an 19 interesting approach and I want to hear more.
20 Secondly, for me thinking about this, this 21 is really complicated. Walt said it's dynamic. It's 22 also stochastic. Before all this starts to happen, if 23 we don't have a BWR with channels -- we have an open 24 area -- we're going to have some natural circulation 25 going on inside the core region in other areas. And NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.
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99 1 it's stochastic. And we're hearing a lot of stuff on 2 the fly. It doesn't seem to me we're ever -- we're at 3 this point, when we're trying to write a letter, are 4 going to resolve these things. And I think the draft 5 letter I've seen has pointed out ways to deal with 6 this so that we can move some of this out into the 7 future. So I -- I think that's a better approach, but 8 I do want to hear everything more that Peter has to 9 say.
10 MEMBER KIRCHNER: So I -- yes. Let's go 11 back to Dr. Yarsky because I think that was a -- we --
12 we broke into the middle of what he had started to 13 allow member input. So Dr. Yarsky, back to you.
14 MR. YARSKY: Thank you, Walt. I would 15 like to take an opportunity to respond to some of the 16 questions and comments raised by the committee members 17 before continuing on the planned content of the 18 presentation with regards to --
19 (Simultaneous speaking.)
20 MEMBER KIRCHNER: Yes, go ahead -- go 21 ahead, Peter.
22 MR. YARSKY: First, Walt, to your comment, 23 I would like to address this concept of the boron 24 concentration remaining above the critical boron 25 concentration. And I think there's a -- perhaps maybe NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.
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100 1 a bit of confusion with regards to the event 2 progression for LOCA versus extended DHRS cool down.
3 In the LOCA progression, because the level drops below 4 the riser holes, there -- the downcomer will become 5 diluted, and the concentration of boron in the 6 downcomer will drop below the critical boron 7 concentration. I think that -- so just to clarify on 8 that point that the -- when the staff considers these 9 flow intrusion phenomena, we are considering them of 10 course for a --
11 (Simultaneous speaking.)
12 MEMBER KIRCHNER: I agree with you, Peter, 13 it will. That was my concern.
14 MR. YARSKY: Right. And it will drop 15 below that concentration. And I don't think there's 16 any -- I think Jose is correctly characterizing this, 17 is that you'll get to some low concentration. It's 18 just however long you let it go, the concentration 19 will just keep getting lower. As to Jose's comment 20 about the reactivity insertion rate, I stand by the --
21 the reactivity insertion rate that's calculated in the 22 white paper. And I think it may be worth trying to 23 spend a couple minutes to clarify that calculation and 24 what's -- what's being assumed and why it's being done 25 that way. But of course, like I will admit, it would NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.
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101 1 be much easier if there was a white board and we could 2 have a conversation and -- and sort of put up equation 3 and such. So we may -- we may reach an impasse over 4 the phone, but I would like to -- to try and discuss 5 that.
6 When we calculate this reactivity 7 insertion rate, we -- step one is to conceptualize a 8 core that all of the fluid -- all of the coolant is 9 this deborated coolant and to calculate what the K 10 effective would be for that scenario. And so that's 11 the -- why we're using the boron coefficients that are 12 reported in Chapter 4 relative to a nominal condition.
13 So it's -- it's not based on the 14 assumption that the -- the front -- and I really 15 hesitate to use language like this because I don't 16 think it's physical. That the -- the front would be 17 impinging on an already critical -- or a condition 18 where the boron concentration is not the critical 19 boron concentration. It's rather, we wanted to 20 calculate the K effective of the core if the boron was 21 removed. And then to postulate if you have a level 22 increase, giving it a rate from the potential change 23 in the core flow, that will translate to a height of 24 that front penetration into the core. And it's with 25 that conceptual picture that we are calculating the NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.
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102 1 reactivity insertion rate.
2 But it is agnostic as to the initial 3 reactivity of the core. So if you think of like 4 reactivity insertion, it's like Delta K by K, and then 5 just thinking of like how Jose has posed it, of course 6 if the initial boron concentration is 6,000 PPM, the 7 K effective at the onset is very low. So Delta K by 8 K will be tremendously bigger. So while I think the 9 -- like I stand behind the staff's calculation, I 10 think there's just a misunderstanding of how we're 11 using the terms to compute what that is, and it's just 12 a difference in the conceptual picture behind how we 13 did that approximation.
14 But I will say that while the -- if you 15 calculate the reactivity insertion rate using Delta K 16 by K, and you have an initially very low K effective 17 -- that that will amplify the delta K by K. You 18 really don't care if you're adding a dollar of 19 reactivity to a core that's subcritical by 20 dollars.
20 It's not safety -- it's not safety significant at all.
21 And I think this feeds into the next 22 concern of that if you have a core at an exceptionally 23 high boron concentration -- say 6,000 PPM -- at that 24 concentration, surely the moderator void coefficient 25 is positive. But the core is so deeply subcritical NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.
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103 1 that the introduction of void -- ultimately, the most 2 void reactivity you could ever insert is to completely 3 void the entire core, and that condition will also be 4 surely subcritical. So having a positive void 5 coefficient under a condition where you're only going 6 from a subcritical condition to another subcritical 7 condition doesn't pose a threat to the safety limits.
8 (Pause.)
9 MEMBER MARCH-LEUBA: Are you done, Pete?
10 MR. YARSKY: I think, with addressing 11 those points. I would like to move on to the 12 discussion of mixing, and then -- and --
13 (Simultaneous speaking.)
14 MEMBER MARCH-LEUBA: I would like to argue 15 with you a little bit and I would like --
16 MR. YARSKY: Okay.
17 MEMBER MARCH-LEUBA: -- and I would like 18 to -- I agree with you that the core will be -- if you 19 have a 6,000 PPM boron concentration in the core, it 20 will be highly subcritical. So then this number, I 21 was pointing it out, of 140 is only to calculate the 22 ramp rate. The real reactivity above K effective of 23 one, you should have used the critical boron 24 concentration divided by the boron coefficient, and 25 that will give you -- your maximum K effective would NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.
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104 1 be 1.02. Okay? That will be calculated with the 2 critical boron concentration, not with the initial 3 boron concentration before the accident happened.
4 But the ramp rate is how fast are you 5 displacing grams of boron from the core? Okay? So 6 even though your final K effective will only be 1.02, 7 the ramp rate will be 5 dollars per minute because 8 you're displacing a lot of grams of boron per minute, 9 because there are a lot of grams of boron. So it will 10 take maybe an hour -- because we're injecting water 11 very slowly -- but eventually we will have displaced 12 80 percent of the core, and we will reach K effective 13 of one. At that point, you will continue to have a 14 five-dollar-per-minute ramp rate.
15 (Simultaneous speaking.)
16 MR. YARSKY: But Jose, the -- the 17 continuation of this rate -- well and I -- of course, 18 I hesitate to talk about it in these terms because I 19 don't think it physically occurs in this way, but you 20 -- that calculation of the rate depends on the initial 21 average boron concentration in the core being very 22 high. By the time you get to the condition where the 23 reactor is critical -- and now there's a potential 24 safety concern -- the K effective of the core is one.
25 So that reactivity ramp rate gets back to the staff's NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.
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105 1 number.
2 MEMBER MARCH-LEUBA: No, it depends on how 3 --
4 (Simultaneous speaking.)
5 MR. YARSKY: The reactivity ramp rate 6 isn't continuous in that perspective because it 7 depends on how much boron is currently in the core, 8 and that ramp rate will decrease as the core is 9 approaching criticality.
10 MEMBER MARCH-LEUBA: Why would it 11 decrease? I mean the -- the boron concentration is --
12 on the top of the core is 6,000. You are still 13 injecting so many grams per minute of the same grade 14 of the beginning.
15 (Pause.)
16 (Simultaneous speaking.)
17 MR. YARSKY: Well, I'm not -- one, yes, we 18 will get to talking about --
19 MEMBER MARCH-LEUBA: Mixing is -- mixing 20 is what saves you. But let me put a final concept, 21 and then I'll shut up. The last time I checked, 22 Jose's gut feeling and head calculations are not an 23 approved method to verify the safety of any reactor.
24 Neither is this, okay? I have been saying it over and 25 over and over that I am not saying that this is going NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.
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106 1 to happen to the reactor. I am saying that it could, 2 and I don't see a calculation that proves it wrong.
3 And I cannot justify, yes, with waving my hands that 4 this is going away because it could be bad. Over and 5 out.
6 MEMBER KIRCHNER: Okay. Dr. Yarsky, back 7 to you please.
8 MR. YARSKY: Okay, so I think the next 9 topic I would like to discuss is the mixing. And what 10 I believe will occur, even before any kind of boron 11 redistribution, but you know once the natural 12 circulation flow loop is broken between the riser and 13 the downcomer, that an internal recirculation flow 14 pattern will develop within the region that's bounded 15 by the riser wall. So this will include the core and 16 the riser region. So there will be a portion of flow 17 that's rising, and a portion flow that's in downward 18 flow, creating an internal recirculation flow loop in 19 that region.
20 That flow loop will contribute to the 21 homogenization of the liquid phase within that region.
22 And what the staff has done in response to this 23 question was to perform a literature review of 24 experimental evidence that demonstrates the phenomenon 25 that lead to these internal recirculation flow NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.
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107 1 patterns, particularly under pool-boiling conditions 2 and two-phase conditions.
3 And so we've looked at a variety of 4 experiments -- both heated and adiabatic -- they show 5 this natural internal recirculation flow loop 6 developing. And have looked at that both in separate 7 effects past as well as integral effects tests. And 8 ultimately, also looked at experimental conditions at 9 the PKL facility for a test that was conducted 10 specifically to look at high boron concentrations from 11 the standpoint of boric acid precipitation, which we 12 believe develops similar from hydraulic conditions to 13 what would be expected for the NuScale plan under ECCS 14 cooling. And you know, that experiment demonstrates 15 that these internal recirculation patterns homogenized 16 the boron concentration -- even below the core, 17 through the core and above the core -- and in the 18 periphery of the core.
19 And so we think that there's a strong 20 experimental basis for believing in the internal 21 recirculation flow pattern, and that such a flow 22 pattern would mix boron inside the core and riser 23 region. This flow pattern develops and is enhanced by 24 the formation of voids, which become channel leading 25 to like an internal core of the flow that is at a NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.
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108 1 slightly higher void fraction and higher upward 2 velocity, and a periphery of the flow, which is in the 3 reverse direction.
4 And because that's the nature of the flow 5 pattern, we believe that mixing will also take place 6 inside the core, which is -- while we've had many 7 discussions about the -- the ramifications that a 8 propagating front through the core may have on 9 reactivity, I have been hesitant to have those 10 conversations because I don't think that's a 11 physically accurate picture. I believe that we have 12 strong evidence that there would be this internal 13 mixing -- this internal recirculation which would lead 14 to mixing, which would disrupt any kind of front 15 propagation through the core.
16 MEMBER KIRCHNER: Can -- Peter, this is 17 Walt Kirchner. I would just concur with you, and if 18 the -- if the concentration of boron is high, it --
19 the details then are immaterial. You will have pretty 20 much a homogeneous core in terms of boron, especially 21 if it's a higher concentration. As you pointed out in 22 your first white paper, effectively that core is then 23 black neutronically as -- as an event progresses.
24 But you've mentioned something -- yes, 25 there's a lot of experimental evidence to back up what NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.
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109 1 you said, and I think when we get to the -- the view 2 graphs, the staff, the members of the committee will 3 see that. What about the mixing from the core into 4 the lower plenum? Have you considered that?
5 MR. YARSKY: So this is -- so this mixing 6 between the core and the lower plenum is something 7 that's predicted in the staff's TRACE calculations, 8 but I am not as confident in that calculation. There 9 is -- so when you're using systems tools to compute 10 the transport of boron through the system -- for 11 instance, in TRACE we assume that it's transported 12 with the liquid phase.
13 And if you want to rely on the TRACE 14 calculation wholly to tell you the evolution of the 15 boron distribution -- and this is something that, in 16 the white paper we have -- we've not done -- because 17 there are numerical considerations that can affect the 18 propagation of boron in such a way that you would have 19 to -- you would have to study the numerical solution 20 and the effect that it has on that mixing.
21 So for instance, in a series of TRACE 22 calculations that we performed, there was a small 23 level oscillation between the collapsed liquid level 24 in the riser section and the level in the downcomer 25 that led to a small amount of sloshing back and forth NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.
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110 1 through the lower plenum. And you know, that sloshing 2 back and forth is going to be sensitive to the time 3 step size that you assume in the calculation. So 4 while I think there will be some of that, I am just 5 not confident enough that we are able to separate out 6 how much of that prediction is coming from the 7 numerical solution and how much of that predicted 8 mixing is physical -- that I think it's -- would be 9 prudent to ignore -- to ignore that -- that mechanism 10 for mixing.
11 And I think that's reflected in the 12 Applicant's analysis. And I think that you've seen a 13 number of times when some things are sort of 14 calculated offline and fed back into a systems 15 analysis. And I think it's just something that's --
16 it's very difficult to -- without a lot more study, at 17 least -- to have confidence in a systems analysis 18 prediction of that kind of mixing ahead of time.
19 MEMBER MARCH-LEUBA: Pete, on TRACE 20 calculations, you have what's called a vessel 21 component, which is a 3D and does include three node 22 --- calculation of the 3D flows in the -- in an open 23 area like the riser. When you get into the core you 24 have chan (phonetic) components which were -- are one-25 dimensional, and you have may have some leak paths NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.
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111 1 between chans. So you go from 3D to 1D and that might 2 be the main cause of why you get flow reversal in the 3 lower plenum because --
4 (Simultaneous speaking.)
5 MR. YARSKY: Well Jose, we don't have 6 channels in -- in this calculation.
7 MEMBER MARCH-LEUBA: Oh, so you have heat 8 -- heat -- heat --
9 MR. YARSKY: Heat structures in the --
10 (Simultaneous speaking.)
11 MEMBER MARCH-LEUBA: Heat structures --
12 MR. YARSKY: And there -- there are 13 different models that we use for different analysis 14 purposes.
15 MEMBER MARCH-LEUBA: It's a very crude --
16 it's a very crude calculation -- to --
17 (Simultaneous speaking.)
18 MR. YARSKY: Yes, but I think we can -- in 19 any case -- and this will be true across like all 20 systems codes. And you're -- you're fundamentally --
21 at some point you're going to have a liquid velocity 22 in the vertical direction, and you're going to 23 multiply it by the time step size, and that's going to 24 translate to like an average nodal density. It's 25 going to feed back into the gravity pressure loss NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.
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112 1 term. And -- so you will have numerical fluctuations 2 in the gravity term that result from whatever the 3 selected time step size is. And so a -- but 4 fundamentally there's just going to be some 5 contribution from that numerical aspect of the 6 solution -- that discretization in time space, and 7 discretization in the axial nodalization. That means 8 the level is going to fluctuate.
9 And I think this level fluctuation is 10 going to produce sort of this sloshing, which for most 11 safety analyses is not important. But for something 12 -- if you're trying to use a systems analysis tool to 13 predict the evolution of the boron concentration over 14 a very long time, if you have some small amount of 15 sloshing from -- that's a numerical artifact, it 16 really presents a challenge to using that systems 17 analysis to quantify how much you can credit that kind 18 of mixing.
19 MEMBER MARCH-LEUBA: That's the -- the 20 bottom line, it is a very difficult problem. But I 21 wanted to put on the record that my intuition agrees 22 with your intuition, Pete, that mixing is -- that the 23 downcomer deborated water will mix with the upper 24 plenum riser before it gets in to the core and causes 25 a criticality. That's what my intuition tells me --
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113 1 (Simultaneous speaking.)
2 MR. YARSKY: Right, yes. And Jose, if you 3 don't mind, could I interrupt for just one second to 4 make a very important clarification -- is that the --
5 the phenomena I was just describing in terms of the 6 sloshing, is mixing -- of like the flow, comes out of 7 the lower plenum and into the downcomer -- and then 8 back and forth. And I want to differentiate that 9 between the internal recirculation driven mixing to 10 sort of clarify that I am talking about two different 11 --
12 MEMBER MARCH-LEUBA: Yes, I understand.
13 MR. YARSKY: Two different phenomena 14 there.
15 MEMBER MARCH-LEUBA: I understand. There 16 will be physical phenomena that will enhance mixing.
17 I asked Delphine, my intuition is sufficient for the 18 blanket statement in the SER and the complete 19 avoidance of a statement on the FSAR that operator 20 actions cannot possibly cause any problem under these 21 conditions.
22 I am with Walt when he says he's at 23 allowing the lower downcomer to deborate is not the 24 desirable condition. And if you want to allow it to 25 deborate, you have to roll up your sleeves and do the NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.
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114 1 little calculations to show that it's okay because 2 many things can go wrong. Okay, I'm done.
3 MR. YARSKY: Okay. The -- so with that, 4 I want to move on to question Bravo, which is about 5 the all rods inserted condition. And you know, while 6 the staff's white paper addresses an all rods out 7 condition, for the most part, it does talk about in a 8 few instances how things would change if the core was 9 controlled, or partially controlled. I mean there will 10 be some sections that try to address that 11 configuration.
12 Here, with the -- if all rods are 13 inserted, that population of control rods creates like 14 a static, constant background negative reactivity 15 insertion so that even if reactivity is being added, 16 kind of a -- the rate at which you would need to add 17 it is much higher to bring the reactor first to a 18 critical condition, and then to insert enough 19 reactivity that you have to -- that you would 20 potentially challenge fuel damage limits.
21 And mixing -- this internal, 22 recirculation-driven mixing is kind of always erasing 23 the reactivity that you're bringing in. So the -- to 24 -- for an all rods inserted case to have prompt 25 reactivity excursion, the mechanism would have to just NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.
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115 1 be faster than even what we considered for the all 2 rods out. And so it's just -- we would perceive it to 3 be a less limiting condition with all rods in.
4 MEMBER KIRCHNER: That makes physical 5 sense, of course, Peter. Could you address, just for 6 clarification, for the record -- you or Ryan -- for 7 the Chapter 15 you assumed -- those analyses were all 8 maximum where rod assemblies stuck out. Is that 9 correct?
10 MR. NOLAN: Yes, that's correct.
11 MEMBER KIRCHNER: Okay, thank you Ryan.
12 Yes. So that's an in-between all rods in and that 13 really beyond-design basis analysis in your first 14 white paper of LOCA plus -- plus --
15 MEMBER DIMITRIJEVIC: Well sir, I'd like 16 to mention -- to ask for clarification here. Does 17 this mean -- so this is a less limiting condition and 18 we need the fast injection, but can this -- but can 19 this happen, you know, the -- that activating charging 20 or something?
21 (Pause.)
22 (Simultaneous speaking.)
23 MEMBER DIMITRIJEVIC: I mean my question 24 is what type of scenario -- what type of the condition 25 will the operator have to create the -- in the -- from NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.
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116 1 the PMA perspectives do we have it also is a huge 2 difference. We are talking 10 to minus six, 10 to 3 minus five difference.
4 So therefore, would this scenario come to 5 be important or not is extremely important on this 6 answer. So is there -- you know, ever some condition 7 which we discuss, like activating -- I assume the --
8 the flooding and drain system has too low injection 9 rate. But can activating charging cause the issue 10 with all rods in?
11 MR. YARSKY: So Vesna, we looked at a 12 variety of mechanisms and tried to break them out into 13 these transient versus prolonged --
14 (Simultaneous speaking.)
15 MEMBER DIMITRIJEVIC: Yes, I had seen that 16 in the previous --
17 (Simultaneous speaking.)
18 MR. YARSKY: So because whatever happens 19 has to overcome the negative reactivity that's 20 provided by the -- the fact that the rods are inserted 21 and they'll stay inserted, I think that you would only 22 need to worry about the transient processes. And 23 those tend to be not associated with operator actions.
24 The operator actions for recovery would be these 25 prolonged injection scenarios, which the staff NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.
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117 1 contends are slow.
2 MEMBER DIMITRIJEVIC: I see. So basically 3 on the -- on the -- on the record, in this -- cannot 4 -- you know, we don't have to be concerned of the --
5 of the -- this type of matter in the -- all the --- we 6 don't have OCWAS (phonetic).
7 (No audible response.)
8 (Simultaneous speaking.)
9 MEMBER DIMITRIJEVIC: If we do not have 10 OCWAS, we don't have to be concerned about this type 11 of --
12 MR. YARSKY: Well I think from a core 13 damage perspective.
14 MEMBER DIMITRIJEVIC: Okay. Because then 15 we have this discussion the last meeting that neither 16 of those scenarios we showed there will -- if 10 to 17 minus five and 10 to minus six, the frequencies will 18 -- they're all -- they're all related to all rods in 19 situation. Because as soon as you have rods out, you 20 are in, you know, frequencies which are -- they're now 21 10 to minus eight or 10 to minus nine, depending on 22 the type of LOCA. So when these scenarios were 23 presented in our last presentation over this diverged 24 opinion, those scenarios were related to no OCWAS 25 scenarios.
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118 1 MR. YARSKY: Right. And Vesna, to be fair 2 to this point, if -- if one adopts the position that 3 there is no internal recirculation and mixing does not 4 occur, then whether or not the rods are inserted is 5 not necessarily an important distinction because one 6 would presume that as you're reflooding the system and 7 you're inputting that deborated water into the core, 8 and it -- if you assume it does not mix, then 9 eventually you'll reach the point of criticality 10 regardless of whether or not the rods are inserted.
11 So you kind of get to the same point eventually if you 12 were to take the position that there is no internal 13 mixing.
14 MEMBER DIMITRIJEVIC: But that's not a 15 point of contention, right? That -- everybody agrees 16 that some level of mixing will be occurring, right?
17 MR. YARSKY: Right. So it -- it certainly 18 is the -- the case that if the rods are inserted or 19 are not inserted, if mixing does occur, then the rods 20 being inserted is less limiting a condition. I would 21 say, however, if one were to take the position that 22 there is no internal recirculation-driven mixing, then 23 the -- the two scenarios look more similar.
24 MEMBER DIMITRIJEVIC: Okay, I get it.
25 MR. YARSKY: Okay. And then for the time NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.
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119 1 being we would like to skip on question Charlie and 2 move to question delta, which asks about the time 3 ranges. And you know, like I will admit that the --
4 the staff originally set off to calculate what these 5 time ranges would be using the TRACE LOCA model.
6 But as I alluded to in an earlier 7 discussion, the TRACE model was predicting this level 8 oscillation-driven sloshing between the core and the 9 downcomer, which led to significant mixing between the 10 downcomer and core concentrations. So we didn't want 11 to rely on the TRACE calculation to address this 12 question. And without the TRACE calculation, we have 13 to resort to performing more hand calculations, or 14 back-of-the-envelope calculations.
15 And unfortunately, such an approach 16 necessitates making assumptions. And so we've tried 17 to address this question of, you know, how quickly 18 does the deboration -- or the boron dilution occur?
19 And you know, how sensitive is that to nominal versus 20 delayed ECCS actuation?
21 And we've developed a table of results.
22 We looked at the amount of time it would take to reach 23 100 PPM based on a post-ECCS downcomer boron 24 concentration and an assumed steaming rate, and 25 calculate that that time frame would be about one day NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.
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120 1 to one week. And then at the time to reach 10 PPM, we 2 also calculated -- and that's something like on the 3 order of one week to two months. And so I -- that's 4 sort of the -- I know that that is a wide range. But 5 with the hand calculations, I don't think we can give 6 a better --
7 MEMBER KIRCHNER: Peter, why did you pick 8 100 PPM as a benchmark?
9 MR. YARSKY: So it's -- yes, this is 10 relatively arbitrary. And I think, you know, you 11 might ask, why don't you calculate it out until you 12 get to zero PPM? When you never get to --
13 (Simultaneous speaking.)
14 MEMBER KIRCHNER: What's of interest to me 15 is calculating when you get to below the critical 16 boron concentration.
17 MR. YARSKY: Well you will be below the 18 critical boron concentration while --
19 MEMBER KIRCHNER: I know and -- and what's 20 of interest is the time intercept of that point.
21 MR. YARSKY: Right. So the -- when we did 22 these calculations, we looked at what the downcomer 23 boron concentration was, like immediately at the time 24 when the ECCS valves open. Now when the ECCS valves 25 open, in the immediate short-term aftermath there's NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.
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121 1 going to be flashing in the downcomer, which is going 2 to increase the concentration.
3 So it will go back above the critical 4 boron concentration. But we would need to do like a 5 systems-type calculation to -- to get that, because we 6 would need to know how much flashing occurs. So we 7 did not rely on the TRACE calculation. Instead we 8 said, we're going to start from what the pre-ECCS 9 boron concentration is. And then given a steaming 10 rate, calculate how much that dilutes.
11 So it would -- in our method that we've 12 used here in the hand calculation, the initial 13 concentration is already below the critical boron 14 concentration. Because we don't credit the increasing 15 concentration from the flashing induced by ECCS. So 16 it's conservative.
17 But then the -- the values of 100 PPM and 18 10 PPM, we said you're starting from somewhere roughly 19 around 1,000 PPM, give or take, so this kind of 20 represents like 90 percent and then 99 percent 21 dilution. Like roughly -- roughly.
22 (Pause.)
23 MEMBER PETTI: So Peter -- this is Dave 24 Petti -- just again, to clarify then -- instead of 25 this idea of having just a -- a few hours time window, NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.
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122 1 which is what we talked about -- our committee talked 2 about a couple weeks ago -- this implies that it could 3 be up to a day longer, depending on when the ECCS 4 actuates.
5 MR. YARSKY: Oh so -- I think that, you 6 know, maybe we -- that the research staff didn't fully 7 understand what the committee wanted to better 8 understand what these questions of the time range is.
9 But I will go back to like an earlier discussion where 10 we talked about the difference between extended DHRS 11 cooling versus LOCA.
12 So in LOCA, you'll have a loss of 13 inventory while the system is still at high pressure.
14 So this is like a very small-break LOCA. And you can 15 uncover the -- you can uncover the riser holes before 16 ECCS. Because like we delay ECCS actuation, which 17 leads to starting the downcomer at a diluted 18 condition. So we might not be looking at the right --
19 the right thing.
20 If you're interested in how long do you 21 operate on DHRS cooling before the downcomer reaches 22 the critical boron concentration, I think that's --
23 that's a different question. I think that's been 24 addressed in the previous meeting. But we're looking 25 at this more from like a LOCA perspective.
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123 1 MEMBER PETTI: Right. No, I'm looking --
2 I'm -- you know, the LOCA happens, the ECCS actuates, 3 but you start to deborate. And in my mind, a clock is 4 ticking because the longer you go, the lower the 5 concentration in the downcomer. And if you have to do 6 something, it's -- it's better to do it when you've 7 got more boron in the downcomer than when you've got 8 less boron in the downcomer. That was kind of the 9 thinking that I thought the committee would have in 10 trying to get an --
11 MR. YARSKY: Right.
12 MEMBER PETTI: -- understanding of what 13 that -- that time window was to operate a recovery.
14 MR. YARSKY: Right, yes I think -- I 15 understand. I understand that concern. I apologize 16 that with the hand calculation I don't think we could 17 really sharpen the pencil enough to give you an idea 18 of how many hours before, you know, necessarily the 19 boron concentration would reach the critical boron 20 concentration.
21 Because as I said, we would need to use 22 something like a systems analysis tool to get the 23 flashing calculation right, which would then affect 24 the -- sort of the starting point for the deboration 25 in terms of the downcomer boron concentration. You NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.
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124 1 know, using this simplistic approach we were able to 2 calculate the times it takes to reach 100 versus 10 3 PPM, just to give an idea of the -- the time frames 4 here.
5 Unfortunately, with a time frame like one 6 day to one week, that puts you -- you know, 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br /> 7 rests within that range.
8 (Pause.)
9 MEMBER PETTI: And Peter -- Dr. Yarsky, 10 that indeed was our concern. As David Petti 11 suggested, we're thinking that this suggests 12 intervention before 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br />. Unless one has high 13 confidence that such an event is not going to happen 14 and -- and that -- and the results would be benign.
15 MR. YARSKY: Well I think that there's a 16 consensus that the boron concentration in the 17 downcomer will decrease in LOCA scenarios.
18 MEMBER PETTI: Yes, to be sure.
19 MR. YARSKY: Right. So I think when --
20 when he said for this to occur, I think the -- when 21 you're referring to would be some sort of 22 perturbation, to use terms that we've used before --
23 some sort of perturbation that could disrupt the 24 system in such a way as to challenge relevant limits.
25 MEMBER PETTI: Yes.
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125 1 MR. YARSKY: Okay.
2 MEMBER PETTI: And you're contending, 3 though, that really it's the mixing that is what 4 really prevents this from becoming a serious event.
5 MR. YARSKY: Correct.
6 MEMBER PETTI: In the core -- mixing in 7 the core.
8 MR. YARSKY: Correct, that when the --
9 (Simultaneous speaking.)
10 MEMBER PETTI: Based on the --
11 MR. YARSKY: -- deboronated water is 12 transported into the core region, that it will mix 13 with the inventory that's there.
14 MEMBER CORRADINI: So Peter, this is 15 Corradini. I am most interested about the 16 experimental analogues. With all due respect to 17 calculations, I am more interested in that. And so 18 those things reside within the -- the closed-session 19 discussion, I assume.
20 MR. YARSKY: Well the slide packages, 21 there's no sensitive information there.
22 MEMBER CORRADINI: Oh, okay.
23 MR. YARSKY: Because the -- the 24 experimental evidence is from the open literature and 25 PKL.
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126 1 MEMBER CORRADINI: Oh, okay. But the PKL 2 -- as I remember PKL, what you're basically saying is 3 you're going to -- you're going to draw in water based 4 on the internal circulation within the core. And that 5 causes the mixing over some time scale that is short 6 enough that you don't essentially get this wave-front 7 effect.
8 MR. YARSKY: Well I wouldn't say that the 9 internal recirculation is driving flow into the core.
10 So you would -- you would have some kind of external 11 mechanism that's pushing water into the core. But 12 just once that water's in the core, I do not believe 13 there's a way for it to be maintained as a static 14 front that then propagates through the core. But 15 rather that it will mix.
16 MEMBER CORRADINI: Okay, but then maybe I 17 should say it more precisely so I understand your 18 point. Your point is, I am in a recovery action I am 19 adding at some rate -- I don't know what it is, but 20 some rate. But that rate is such that the mixing 21 essentially allows it to turn over and mix within the 22 core due to these circulation patterns?
23 MR. YARSKY: Correct.
24 MEMBER CORRADINI: Okay. All right, thank 25 you. And then the PKL is the example case that's most NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.
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127 1 appropriate from an experimental standpoint, as I 2 remember your discussion.
3 MR. YARSKY: Well I would say that the PKL 4 test most directly measures the effect that the --
5 that this has on the distribution of the boron 6 concentration spatially.
7 MEMBER CORRADINI: Okay, thank you very 8 much.
9 MR. YARSKY: Because the PKL tests --
10 because the purpose of the test was the study of boric 11 acid precipitation, you know, there were measurements 12 made -- and redundant measurements made of the 13 distribution of the boron concentration during the 14 test.
15 MEMBER CORRADINI: Thank you.
16 CHAIR SUNSERI: So Walt, this is Matt. I 17 just want to break in here, and I know we have more of 18 this discussion to go. But I would like to start 19 looking for a break point to where we can break for 20 lunch. And then what I am going to propose is that we 21 take a longer lunch break than normal. I am going to 22 propose an hour and a half for lunch break, with the 23 purpose of that being to give members some time to 24 review some of this new information that is being 25 posted to our SharePoint so that when we resume after NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.
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128 1 the break, we will be a more informed of the 2 discussion that is going to occur. Does that make 3 sense?
4 MEMBER KIRCHNER: Yes, that does. And 5 also we -- once the members have a chance to look at 6 Dr. Yarsky's view graphs, we may not need a closed 7 session. We've -- we've pretty much aired things.
8 But if Peter or anyone else feels that's necessary, we 9 can do that.
10 MEMBER RICCARDELLA: This is Pete. And 11 you know, I've spent little time looking at the --
12 that view graph package. And as a non-13 thermodynamicist, it's Greek to me. And I just -- I 14 can't make any sense out of the package without some 15 explanation, I think.
16 MEMBER KIRCHNER: Yes. I think the 17 summary is that there's ample evidence, and as Dr.
18 Yarsky addressed Dr. Corradini's question, the PKL 19 German facility was used to do good measurements of 20 boron redistribution. They were worried about a 21 different problem, and that was precipitation of the 22 boron out of the system, but -- but the results of 23 those experiments show good -- good mixing, which 24 supports Dr. Yarsky's contention. A lot of the other 25 experimental -- just for the public record -- the view NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.
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129 1 graphs we're referring to have additional experimental 2 information, all of which suggest that there's --
3 because of thermal-induced currents and such -- good 4 mixing within the core region. And that would just be 5 backup evidence for the -- for that postulation.
6 MEMBER RICCARDELLA: I believe we had a 7 request in to NuScale to review those view graphs to 8 see if they're anything -- if there is anything in 9 them that really is proprietary and can't be covered 10 in a public session. Maybe if we could have that --
11 (Simultaneous speaking.)
12 PARTICIPANT: Mr. --
13 MEMBER RICCARDELLA: In answer to that 14 question before --
15 MEMBER KIRCHNER: I think we have an 16 answer, Pete, already to that --
17 (Simultaneous speaking.)
18 MR. MOORE: Mr. Chairman? This is Scott 19 Moore. So Dr. Yarsky said that there's nothing 20 proprietary in them. But as of mid-morning, NRR was 21 asking us to treat them as proprietary. Bruce -- and 22 my request was to NRR. Bruce, has NRR made a decision 23 on whether we should treat them as proprietary or not?
24 The backup slides?
25 MR. BAVOL: Okay, for the backup slides --
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130 1 this is not the white paper. They're still -- NuScale 2 is still reviewing that paper --
3 MR. MOORE: Yes.
4 MR. BAVOL: -- for proprietary -- the 5 backup slides have come back with no proprietary 6 information. That information just came back to me.
7 So --
8 MEMBER RICCARDELLA: So if we wanted to, 9 after lunch, we could bring up those slides in the 10 open session and have Dr. Yarsky go through them?
11 MEMBER KIRCHNER: Yes, I think we could do 12 that, Pete. And he could probably quickly go through 13 the -- the most important of those. Thank you, Bruce.
14 (Simultaneous speaking.)
15 VICE CHAIR REMPE: Could we have, before 16 we break to lunch, the answer to question three, or --
17 yes, question three? It's not C, it's three I guess.
18 And sometimes -- the instrumentation question.
19 There's not a lot of text that I see. So I -- I don't 20 think it's -- I'd like to have Peter there as well as 21 the instrumentation folks because in Peter's paper, he 22 often mentions the operators are looking at water 23 level, whereas the -- I think the response is going to 24 heavily rely on flex level type measurements. And I 25 just am curious of -- it seems like the operators NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.
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131 1 would like some backup with water measurements. Could 2 we kind of hear their first response from the staff on 3 it before we break for lunch, and make sure we kind of 4 air a few things?
5 MEMBER KIRCHNER: Matt, are you amenable 6 to one more question being --
7 CHAIR SUNSERI: Right, if they -- I mean 8 if they believe they can answer it in a short -- you 9 know, a few minutes -- period of time. We're not 10 going to get in a long debate like we have in the past 11 on some things.
12 MEMBER KIRCHNER: So I'll turn to the 13 staff. Is -- I am -- I am not sure if this is Ryan or 14 Dr. Yarsky, or someone else was going to address that 15 question.
16 PARTICIPANT: Dinesh, are you on?
17 MEMBER KIRCHNER: Or Dinesh, yes.
18 (No audible response.)
19 MR. TANEJA: Yes, I am here.
20 (Pause.)
21 CHAIR SUNSERI: So question number three 22 on the list -- are you prepared to answer that 23 question now?
24 PARTICIPANT: Dinesh, this is the level 25 instrumentation question.
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132 1 MR. TANEJA: Well the level 2 instrumentation is designed to be available in a post-3 accident scenario. Now the measurement uncertainties 4 are calculated in the set-point methodology for those 5 instruments for the pressurizer level range.
6 And even though it's the same sensor which 7 measures the entire, you know -- the riser and the 8 pressurizer. But the way right now the level of 9 interest was the pressurizer level, so there's a 10 calibrator span of the pressurizer level that, you 11 know, is in the set-point methodology calculation 12 where they have calculated the overall uncertainty 13 which considers all the effects, including, you know, 14 what the conditions are in a post-accident scenario.
15 So that's the same sensor. So it is designed to be 16 available to the operators with a known uncertainty.
17 You know of measurement --
18 VICE CHAIR REMPE: Why don't you go ahead 19 and say that number for the uncertainty? I don't 20 think it's proprietary. It's in the FSA -- or the DCA 21 document. It's quite high.
22 MR. TANEJA: It is high. Yes, I am not 23 saying that it's not high. The total is proprietary 24 -- that's in the set point methodology document.
25 VICE CHAIR REMPE: I thought the --
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133 1 Chapter 7 of the SAR has like plus or minus? And I 2 don't have it pulled up, but I thought it -- it's 3 pretty high. And so I just kind of --
4 MR. TANEJA: Yes.
5 VICE CHAIR REMPE: -- wanting to hear 6 Peter's response when he hears that number and -- is 7 that going to give the operators good guidance when 8 they could be off that much?
9 MR. YARSKY: So Joy, in the original white 10 paper we considered a variety of operator actions.
11 And I tried to put it in the perspective that without 12 emergency operating procedures, a lot of the 13 postulated operator actions that are there are just 14 sort of like our speculation in a way. But the -- I 15 think the specific section that you're referring to 16 deals with, if there's a small-break LOCA, and then 17 there's a failure of the rods to insert, and then 18 there's a failure of the ECCS valves -- that the 19 operators would diagnose that condition based on a 20 continuing decrease in the level. And that in that 21 specific beyond-design basis scenario, the operators 22 will rely on the CVCS to provide makeup to the vessel 23 to recover the level -- or maintain the level -- when 24 ECCS is not available because it somehow failed.
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134 1 I don't have the Chapter 7 right up there, but again, 2 there's a lot of uncertainty in those measurements.
3 It's going to be very up and down-ish. We're talking 4 about the guided wave -- you know, it's -- you're 5 going to be relying on this and it could be off 6 considerably. And if it's got, like, a lot of up and 7 downing with the water level --
8 MR. YARSKY: Yes, certainly.
9 VICE CHAIR REMPE: It could -- yes, 10 there's going to be a lot of things that need to be 11 thought out carefully in such a situation, and the 12 sensors -- because, a long time ago we didn't think 13 the operators would need to figure out the -- rely on 14 the water level within the --
15 MR. YARSKY: Well, it's like -- if I might 16 continue, in -- in this --
17 (Simultaneous speaking.)
18 VICE CHAIR REMPE: Yes, please do.
19 MR. YARSKY: -- particular beyond design 20 basis sequence, the -- you're relying on that 21 injection because the ECCS has failed. So this occurs 22 relatively early, you know, because you -- you really 23 don't really start deborating the downcomer until 24 after you've lowered the level below the riser holes.
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135 1 going to really start lowering the level. So this 2 will occur relatively early. And if the ECCS fails, 3 that's when the operators would switch to the backup 4 systems, which in this case would be maybe CVCS, to 5 inject. And I think that the -- the boron 6 redistribution issue just isn't significant because 7 this would be something that would be done very early.
8 MEMBER KIRCHNER: Yes. Joy -- yes, this 9 is Walt. I would concur with Dr. Yarsky.
10 Pragmatically, once you entered into this kind of a 11 scenario and you did your diagnostics, you would 12 inject early and often. Trust me. That would be the 13 response. You would go -- and -- with the CVCS system 14 and just do that. So the -- the uncertainty in the 15 level measurement is not really as important as the 16 detection of the situation you're in -- and then 17 intervening and injecting water. Do you follow my 18 drift? The precision in that --
19 (Simultaneous speaking.)
20 VICE CHAIR REMPE: I can see what you're 21 saying ---
22 MEMBER KIRCHNER: -- in that downcomer --
23 riser and downcomer is not an important factor in the 24 operator response. What you will do is try and 25 recover. And that will turn you to the -- the first NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.
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136 1 line of defense will be the CVCS system. And the 2 operating procedures. I am of course speculating, but 3 I am pretty confident this is exactly what the EEOP 4 would direct you to do.
5 (Simultaneous speaking.)
6 VICE CHAIR REMPE: So is section --
7 (Simultaneous speaking.)
8 MEMBER KIRCHNER: So you don't need a 9 precise -- you don't need a precise level measurement 10 is the point.
11 VICE CHAIR REMPE: Peter, are we talking 12 about Section 3.6 of your first white paper where you 13 mention flow reversal and void eruption? And having 14 the level in the down cup over-swell? And flashing 15 occurring? And it just seems like you're going to be 16 -- the operators are going to be trying to rely on 17 some instrumentation that isn't going to be giving you 18 anything near -- it's going to be beyond inches. It's 19 going to be in a feet level that you're -- that they 20 may have some uncertainty. That's where I am talking 21 about.
22 MR. YARSKY: So Joy, I was -- I thought we 23 were referring to Section 6.7 which is the -- manual 24 CVCS operation is ECCS backup. But you were -- you 25 were talking about section 3 point --
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137 1 VICE CHAIR REMPE: Six -- there's several 2 places in your paper that you refer to the operators 3 doing things, or monitoring things based on the water 4 level. And I was --
5 (Simultaneous speaking.)
6 MR. YARSKY: -- yes.
7 VICE CHAIR REMPE: -- man, I don't know if 8 I -- and again, I am not sure this can be dealt with 9 now. I am back with what Dennis said. And actually 10 what Anna had said a long time ago -- what can the 11 staff really do at this time? And I guess it's going 12 to be something that maybe the COL item is going to 13 need to elaborate -- it would make me happy if they 14 would elaborate a little bit more of what they expect 15 to see the COL applicant provide to address some of 16 these concerns raised in this discussion. And -- so 17 anyway, I will let you answer the question about 3.6, 18 but the discussion about the -- what I see in your 19 second white paper is it kind of reflecting what I was 20 looking at when I saw your first white paper about the 21 instrumentation.
22 MR. YARSKY: Yes, so -- this is -- this is 23 a very good point. And, you know, I think I could 24 have done a better job in the white paper of 25 clarifying what the -- the -- sort of the purpose and NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.
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138 1 scope of the discussion of Section 3. So in Section 2 3 of the original white paper, the intent was to 3 describe the progression of a -- of an event. This is 4 the -- a kind of activity that the staff will often 5 undertake to just get -- to look at an event 6 progression and try and break that event progression 7 down into phases because the phenomena that are 8 important can vary from one phase of an event to 9 another phase of the event. And in this description 10 of these different phases of the event, I think that 11 what causes that transition from one phase to another 12 phase is very often dictated by where the reactor 13 water level is. So for instance, if the reactor water 14 level remains above the top of the riser, the flow 15 conditions are very different, you know, and the 16 phenomena that are important will be different under 17 that condition than once the level drops below the top 18 of the riser.
19 And I think in that discussion of the 20 events, we talk about different potential operator 21 actions. You know, but I -- I believe that the 22 different operator actions would primarily be focused 23 on trying to insert control rods. And you know, they 24 would be a -- a generally, like a symptom-based 25 approach to the procedures. So I don't think that NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.
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139 1 necessarily the -- the operators would be relying on 2 level instrumentation to identify which phase of the 3 event they're in to then, you know, perform actions 4 for that event. It was kind of meant more to be an 5 exercise to help the -- the staff understand during 6 which phases of the event different phenomena would be 7 important.
8 VICE CHAIR REMPE: So you're saying the 9 operator is going to rely on the symptoms of the event 10 and -- what will they use to identify the symptoms of 11 the event? Just flux detectors?
12 MR. YARSKY: Well I think that that will 13 be -- like we'll -- it's going to be how the EOPs are 14 crafted, right? So generally an EOP is crafted from 15 the perspective of using a symptom-based approach.
16 But you know, I -- I haven't seen the EOP, so I am not 17 sure, you know, what the COL applicant will -- will 18 come up with at that point.
19 PARTICIPANT: You know -- that's right, 20 Peter. Typically, Joy, you know when they develop 21 these procedures, they're -- then it's more symptom-22 based and -- and prescriptive a response. They're 23 going to have other things at their disposal. They're 24 going to see pressure in both the primary system and 25 the containment. That's the first indication of a NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.
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140 1 LOCA that -- the ladder pressure measurement, et 2 cetera. So they'll -- they'll have a number of things 3 at their disposal that will trigger them to enter into 4 the EOP response.
5 VICE CHAIR REMPE: So again -- I'm back to 6 where I would feel a lot more comfortable if -- in --
7 that's something we can discuss later as a committee 8 -- if we had a little more specificity of what we 9 expect the COL applicant will provide because it seems 10 like -- people are saying, well, I think it will be 11 there. Yes, you're right. They'll have pressure 12 transducers. But -- and they'll have some sort of 13 flux detection. But what is needed to give the 14 operator good guidance on how to say, yes -- and the 15 staff as they review it -- that they believe that 16 there is a way out of this event. And I will shut up 17 there. But -- and we can look at the information we 18 were given.
19 (Simultaneous speaking.)
20 PARTICIPANT: Yes, and Joy, this is a very 21 important point -- oh, sorry.
22 CHAIR SUNSERI: No, I think we're into 23 report preparation now, so we can stop this --
24 (Simultaneous speaking.)
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141 1 something to this because even it wasn't the -- one of 2 the question, which wasn't responded yet was the C 3 about instrumentation, and the type of recovery 4 action. I just want to say, when we are discussing 5 these human -- the procedures and everything, this is 6 okay, it will be done in the color phase. But design, 7 which will help operators perform those -- you know, 8 perform those actions, should be done in this phase.
9 It's not something that applicant will be adding 10 instruments, or the way to inject the bottom to this 11 -- so it should be some general description of this 12 recovery actions. What instruments they're going to 13 use it, and how they're going to inject -- given all 14 of this, you know, containment installation issues for 15 their LOCA, OCWAS, how they're going to -- so this --
16 even those in procedures -- procedure will just 17 describe operators do given the design agreement. So 18 therefore, we need to have a description of this 19 recovery action, knowing that the design is going to 20 provide that we --
21 (Simultaneous speaking.)
22 CHAIR SUNSERI: So -- so that's good input 23 for our letter report. I think, you know, we -- we 24 know -- we have been given all the technical 25 information that is available on this topic right now.
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142 1 We can write our concerns in the -- in the report. So 2 at this time I'd like to break for lunch. We are 3 going to take an hour-and-a-half lunch break. We will 4 reconvene at 2:30 Eastern Time. And when we 5 reconvene, we will pick up with the question and 6 answer period, which will involve a review of the 7 slides that have been provided to the members --
8 applying here. And then I am told that NuScale has 9 some technical remarks that they want to make 10 following the Q&A. So we will allow some time for 11 that. And then we will address any member final 12 concerns and then move into report preparation. So 13 any questions with where we are heading for the rest 14 of the day?
15 (No audible response.)
16 CHAIR SUNSERI: Okay. Thank you and it is 17 1:00 p.m. We are recessed now until 2:30 p.m.
18 (Whereupon, the above-entitled matter went 19 off the record at 1:01 p.m. and resumed at 2:31 p.m.)
20 CHAIR SUNSERI: It's 2:30. We are going 21 to reconvene. I will begin with the roll call. Ron 22 Ballinger?
23 (No audible response.)
24 CHAIR SUNSERI: Ron, are you on mute?
25 (No audible response.)
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143 1 CHAIR SUNSERI: Dennis Bley?
2 (No audible response.)
3 CHAIR SUNSERI: Can anybody hear me?
4 MEMBER KIRCHNER: Yes, I can, Matt.
5 VICE CHAIR REMPE: Yes, we can hear you.
6 CHAIR SUNSERI: Okay. Charles Brown?
7 (No audible response.)
8 CHAIR SUNSERI: Well, I'm not going to 9 give an hour and a half lunch break anymore, am I.
10 Vesna Dimitrijevic?
11 (No audible response.)
12 MEMBER KIRCHNER: Matt, I'm concerned that 13 perhaps you might have said 2:45 which is --
14 (Simultaneous speaking.)
15 VICE CHAIR REMPE: We're getting messages 16 from Dennis that says he can't turn his mic on, 17 although --
18 MEMBER KIRCHNER: Okay. That's the 19 problem. Okay.
20 VICE CHAIR REMPE: Yeah.
21 CHAIR SUNSERI: Okay. So there may be 22 something --
23 MEMBER BROWN: I've got it back now. Hey, 24 Matt.
25 CHAIR SUNSERI: Yeah, yeah.
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144 1 MEMBER BROWN: Somebody had muted us.
2 MEMBER BALLINGER: Yeah, this is Ron. I'm 3 here.
4 MS. LUI: I just repeat the action of 5 unmuting everybody. So everybody should be unmuted.
6 CHAIR SUNSERI: Okay. All right.
7 MEMBER PETTI: This is Dave. I'm back on.
8 MEMBER BROWN: Okay. You want to start 9 over?
10 CHAIR SUNSERI: Let me start over. All 11 right. Ron Ballinger?
12 MEMBER BALLINGER: Here.
13 CHAIR SUNSERI: Dennis Bley?
14 MEMBER BLEY: It works now. I'm here.
15 CHAIR SUNSERI: Okay. And I apologize 16 about my comment of giving too long of a lunch break.
17 Charles Brown?
18 MEMBER BROWN: I'm here.
19 CHAIR SUNSERI: Vesna Dimitrijevic?
20 MEMBER DIMITRIJEVIC: Here.
21 CHAIR SUNSERI: Walt Kirchner?
22 MEMBER KIRCHNER: Here.
23 CHAIR SUNSERI: Jose March-Leuba?
24 MEMBER MARCH-LEUBA: Yes.
25 CHAIR SUNSERI: David Petti?
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145 1 MEMBER PETTI: Yes.
2 CHAIR SUNSERI: Joy Rempe?
3 VICE CHAIR REMPE: Here.
4 CHAIR SUNSERI: Pete Riccardella?
5 MEMBER RICCARDELLA: Here.
6 CHAIR SUNSERI: And myself. All right.
7 We have 100 percent available and a quorum. Let me 8 just provide a couple of comments here before we get 9 started and just take this in the vein of just trying 10 to move things along here. So I do appreciate the 11 fact that Committee members have a lot of concerns or 12 some concerns at this point they're feeling 13 unfulfilled.
14 I believe we're getting to the point of 15 what I'll call diminishing returns on keeping to press 16 the staff and NuScale for a resolution on all our 17 concerns. And primarily, I think it's because as the 18 design has progressed this far, it still has more to 19 go. And what's left I think is where a lot of our 20 questions remain to be answered. So continuing to 21 press now for things that don't exist or not capable 22 of being presented at this time, it's just not going 23 to help.
24 So what I would suggest is that we as a 25 member of the Committee need to be mindful that at the NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.
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146 1 end of the day, we report to the Commission and we 2 have to provide our recommendation on whether or not 3 we support the staff with the issuance of a design 4 certification or not. And so I think a lot of the 5 discussion that I'm hearing is bordering on 6 discussions that we need to be having in Committee 7 along those lines and not having to debate those any 8 further with staff or NuScale.
9 So Walt, what I'm going to suggest is that 10 we proceed through the rest of the afternoon, hear 11 from the staff on the rest of our questions, and hear 12 from NuScale on the technical information they want to 13 provide. And then we just have to move into our 14 deliberations and decide for ourselves, have we heard 15 enough from staff and NuScale? Have we seen enough of 16 their work, and is the design sufficiently progressed 17 at this time that we can make a safety judgment on the 18 design certification, standard design authorization at 19 this point in time? And we do that through our formal 20 letter reports which are always factually based with 21 conclusions that are derived from those facts. So 22 anybody have any comment or anything they want to say?
23 (No audible response.)
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147 1 before we got into it. Scott?
2 MR. MOORE: Thank you, Mr. Chairman. And 3 this is for both the members and everybody else, all 4 the other participants online. This morning, there 5 were two documents that were discussed. One is backup 6 slides by Dr. Yarsky. The other is a proprietary 7 second white paper from Dr. Yarsky.
8 As you heard, Members, the backup slides 9 are now nonproprietary, and those are being made 10 available to members of the public. And we will make 11 them more widely available soon. The proprietary 12 second white paper -- and if NRR could confirm this --
13 I believe is being reviewed for -- and prepared in a 14 nonproprietary version. And as soon as we get the 15 nonproprietary version, that version will be made 16 available as well publicly. Could NRR confirm that a 17 nonprop version is being prepared?
18 MR. BAVOL: This is Bruce Bavol, Project 19 Manager, NRR. Yes, currently NuScale is performing a 20 proprietary review of the white paper from Dr. Yarsky.
21 As soon as that information gets back to us, if there 22 is any redacting that needs to be had, we will redact 23 the paper and prepare a publicly available version and 24 place that version into ADAMS and provide the ACRS 25 membership with that information.
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148 1 MR. MOORE: Okay. Thank you very much.
2 That's all that I wanted to make everybody aware of, 3 that we will make those documents available for 4 everyone's benefit. Thank you, Mr. Chairman.
5 CHAIR SUNSERI: Okay. Thanks, Scott. And 6 I know there was a little bit of anxiety around that 7 today, and we appreciate the fact that a lot of this 8 information is late breaking and therefore did not 9 have the time necessary to go through appropriate 10 review before we could make the public disclosures.
11 But those are -- processes are being followed and the 12 disclosures will be forthcoming.
13 So thank you for those clarifications and 14 confirmations. At this point, I would now turn to 15 Walt to continue facilitation of the Q&A with the 16 staff, and then we will take member comments and then 17 hear from NuScale and then try to wrap up the 18 presentation of information before we roll into our 19 report preparation. So Walt, go ahead.
20 MEMBER KIRCHNER: Just two comments, Mr.
21 Chairman. Also we would like a very brief 22 presentation of the backup view graphs now that we 23 know that we can use them in an open session. And 24 then we have to remember to allow time for public 25 comment at the end before we break for our letter NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.
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149 1 writing session.
2 CHAIR SUNSERI: Right, absolutely. Thanks 3 for reminding me of that, Walt. Appreciate it.
4 MEMBER KIRCHNER: So turning to the staff, 5 I think we had one question remaining if I'm correct.
6 And I don't know if that's Dr. Yarsky or Dr. Nolan or 7 who from the staff will take that -- finish the Q&A 8 part of the session?
9 MR. YARSKY: Walt, this is Dr. Peter 10 Yarsky from the research staff. Before lunch, we were 11 discussing Question C --
12 MEMBER KIRCHNER: Yes.
13 MR. YARSKY: -- which we were prepared to 14 discuss after addressing all the other questions. But 15 I don't know if the Committee wants to continue 16 discussion of Question C or if we should pick up with 17 Question D.
18 MEMBER KIRCHNER: Let's go in order.
19 Let's do C and D, and then I believe that's the list.
20 MR. YARSKY: Yes, I believe -- do we have 21 Dinesh on the line?
22 MR. TANEJA: Yes, I'm here. Peter, can 23 you hear me?
24 MR. YARSKY: And so I'm wondering if we 25 have anything else to discuss with respect to Question NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.
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150 1 C.
2 MEMBER KIRCHNER: I thought we were 3 finished, Dr. Yarsky. I thought Dinesh summarized 4 things. There will be instrumentation to measure 5 level. It will be qualified. I don't believe the 6 applicant has made their final selection on 7 instrumentation type. But I believe Dinesh answered 8 the question, unless there's further comment from the 9 Committee.
10 MEMBER DIMITRIJEVIC: The concern wasn't 11 only about instrumentation. It was about what needs 12 to be done and can this be done. So my concern, we 13 all have idea what needs to be done. Only the 14 question is, what does this -- actually, literally, 15 what needs to be done, the description --
16 MEMBER KIRCHNER: Vesna, please could you 17 narrow that down? A lot remain to be done.
18 (Simultaneous speaking.)
19 MEMBER DIMITRIJEVIC: This is what I'm 20 asking. So how are we going to recover? That's my 21 question. If we're going to recover, we're going to 22 inject the boron. How are we going to inject boron?
23 We have a containment ventilation signal in the case 24 of the LOCA and ATWS. So my question is, what needs 25 to be done basically, that this containment NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.
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151 1 ventilation signal can be bypassed. And what else 2 needs to be open? I just want to know what equipment 3 is desirable.
4 MR. YARSKY: Yeah, so Vesna, I'll try to 5 address this in a general way because, as we said, 6 there's no procedure -- no procedure has been 7 submitted for NRC review at this stage. But there --
8 MEMBER DIMITRIJEVIC: Right. And I'm not 9 interested in procedure. I'm interested in equipment.
10 MR. YARSKY: Right. So the -- so 11 equipment that will be available includes the CVCS and 12 the CFDS which because of isolation signals would be 13 available for injection but could only inject high 14 concentration -- a high concentration of boric acid 15 coolant. So think like 4,000 ppm, give or take. And 16 the only other comment I think I would have to add is 17 that there' nuclear instrumentation available and that 18 could be used to monitor subcritical margin, as is 19 done during startup.
20 VICE CHAIR REMPE: So I think when we left 21 off before lunch, you had emphasized, well, there'll 22 be symptom-based procedures when they're developed.
23 And I guess where I'm still not sure and perhaps none 24 of us are is how will the operators diagnose what 25 condition the reactor is in during these types of NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.
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152 1 situations so that they can say what needs to be done.
2 And again, although as Walt pointed out, the actual 3 sensors have not even been decided upon, their 4 accuracy is specified in the DCA. And is that 5 adequate with that range of uncertainty?
6 MR. YARSKY: This is Peter Yarsky from the 7 staff again. I think just from a philosophical 8 standpoint that monitoring subcritical margin during 9 starting and monitoring subcritical margin during any 10 hypothetical recovery maneuver I think would be 11 fundamentally the same. And the same instrumentation 12 could be relied upon for either maneuver.
13 VICE CHAIR REMPE: But you may not know 14 what the water level is. And when you don't know that 15 and you don't know, yeah, you'll have some sort of 16 subcriticality flux detector that can monitor changes 17 in the period. But you won't know whether that's due 18 to voiding. You won't know what the water level is.
19 I think there's going to be some uncertainty that will 20 take a while to figure out exactly how you'll be able 21 to, with some confidence, diagnose the condition of 22 the patient.
23 MR. YARSKY: Right. I certainly think 24 that they'll have to be -- like, some more work will 25 have to be done at the point where these kinds of NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.
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153 1 procedures are developed because it will depend on a 2 lot more than just like this high level discussion.
3 And certainly, like, how instrumentation readings are 4 affected, for instance, but the environmental 5 conditions, right? So instruments may develop 6 environment-specific biases and uncertainties that 7 would have to be considered. I just think that would 8 have to be part of a later submittal.
9 VICE CHAIR REMPE: And the COL item --
10 MEMBER KIRCHNER: That's a typical product 11 qualification.
12 VICE CHAIR REMPE: -- was kind of vague on 13 -- I'm sorry. Are you talking to me, Walt? But 14 anyway, I think the COL item as it stands today 15 doesn't give anybody a clue of what's going to be 16 expected from the staff. And if you need to change 17 some of those accuracies since we've not really had a 18 chance to think about this carefully.
19 MR. TANEJA: This is Dinesh. May I add 20 something?
21 MEMBER KIRCHNER: Go ahead, Dinesh.
22 MR. TANEJA: Yes, so the way NuScale has 23 proceeded with the instrumentation is that they have 24 selected the types of sensors and they have 25 theoretically calculated these uncertainties based on NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.
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154 1 the environmental condition. Now these are not the 2 actual numbers that would be based on the actual 3 testing which they would do during the COL, I guess, 4 construction stage. But the numbers that they have 5 calculated are the numbers that are assumed in the 6 accident analysis.
7 So it's like the accident analyses are 8 based on assumptions which are validated by the -- in 9 the calculation that are performed for the total loop 10 uncertainties. Now the instrumentation information 11 that would be available is your riser level, your 12 pressurizer level, your pressurizer, reactor coolant 13 pressure, reactor coolant temperature, and the nuclear 14 instrumentation. So those instrumentations are 15 designed to be available.
16 And to answer the question about the 17 containment isolation signal override capabilities, 18 yes, a design has the capability to override the 19 containment isolation signal and selectively open flow 20 paths. So this is all administratively controlled, 21 and that's where the procedures are able to take 22 advantage of these features that are there in the 23 design.
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155 1 in the RPV is similar to the one in the CNV. And they 2 have a preferred one at this time. But the advanced 3 sensor reports, it's very clear to say we've not 4 finalized the qualification for that sensor. And they 5 basically have relied on the specifications that the 6 staff and the applicant have agreed upon for that 7 sensor. Is that not a true statement, Dinesh?
8 MR. TANEJA: Right. So there is the 9 manufacturer specification. And then what the NuScale 10 did is they have basically based on some data that 11 they have, they have come up with the assumed 12 uncertainties during accident conditions, for example.
13 So the overall total loop uncertainty that they have 14 calculated has taken into consideration all the 15 environmental impacts.
16 VICE CHAIR REMPE: And when they did this 17 with the reactor vessel, this whole thing about boron 18 dilution has not even come to light, that the 19 operators would have to think about long-term 20 recovery. That wasn't considered when that was all 21 specified, right?
22 MR. TANEJA: Okay. So the thing is there 23 are no manual operator action under the design basis 24 condition. So there are no Chapter 15 events that 25 require a manual operator action. So all the NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.
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156 1 automatic actions that are relied upon, so that 2 analysis assumes this uncertainty which bounds the 3 uncertainty that's calculated based on the best 4 available data at this time which would be validated 5 during the EQ testing and seismic testing of the 6 actual instrumentation. So --
7 VICE CHAIR REMPE: That's --
8 MR. TANEJA: -- what we have is we have a 9 bounding uncertainty values which are correlating with 10 what's assumed in Chapter 15 and then the analyses.
11 So all your analyses are actually based on those. So 12 the assumptions are actually conservative compared to 13 what's calculated. So they --
14 VICE CHAIR REMPE: So that --
15 MR. TANEJA: -- just need to demonstrate 16 that they stay within those assumed values.
17 VICE CHAIR REMPE: So those calculations 18 were done before this whole boron dilution thing --
19 MR. TANEJA: Exactly.
20 VICE CHAIR REMPE: -- came to be. And so 21 what I'm trying to get to is the question when Peter 22 was doing his analysis, did he say, okay, the operator 23 is going to be watching this in that section -- was it 24 3.6 I mentioned earlier, Peter? When you were talking 25 about that flow and things going back and forth and NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.
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157 1 voiding, did you consider that the operator may -- I 2 don't know what. I guess we're not allowed to say the 3 accuracy aloud.
4 I still haven't found that table during 5 the lunch break. I was doing some other things. But 6 did you consider the specific uncertainties that are 7 allowed for that sensor when you said, oh, yeah, the 8 operator will be able to detect that the water is up 9 or down?
10 MR. YARSKY: So Joy, this is an excellent 11 question. In the original white paper analysis, we 12 just assumed that the operator would not monitor. It 13 would just initiate the system and just allow it to 14 evolve. But this is not a realistic approach.
15 Realistically, the operators would monitor the 16 condition as it evolves and would not just turn on an 17 injection source and leave it one.
18 VICE CHAIR REMPE: And so if they are 19 realistically monitoring that, that's where I kind of 20 go, I'm wondering if they're going to have some 21 confusing signals which has occurred in the past with 22 real reactors that have had some severe accidents 23 occurring.
24 MR. YARSKY: Right. I think that --
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158 1 really would like to see something stronger about what 2 the staff would expect in that COL item.
3 MR. TANEJA: So Joy, for example, the 4 boron redistribution issue, so the design change added 5 a new ECCS actuation signal based on the reactor 6 coolant pressure. So the analytical limit is 800 7 PSIA. What's assumed in the analysis, it's plus or 8 minus 100 PSI.
9 VICE CHAIR REMPE: I'm happy with the fact 10 they added the pressure signal to initiate ECCS.
11 MR. TANEJA: Right. So the --
12 VICE CHAIR REMPE: That's made me very, 13 very happy.
14 (Simultaneous speaking.)
15 MR. TANEJA: So the analysis assumed 100 16 PSIA uncertainty for that value. Okay? So the 17 analysis is actually run assuming a set point of 900 18 PSI plus or minus 100 PSI, where the analytical limit 19 is 800. And the set point calculation that they 20 performed is actually within that assumed 100 PSIA for 21 that value under that condition.
22 Now the as built has to be done, and they 23 had to assure that the assumptions are validated when 24 they actually designed the instrumentation and test 25 them. But this is what we found when we evaluated it, NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.
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159 1 that the calculated uncertainties are bounded by the 2 assumed uncertainties in Chapter 15 and then the 3 analyses. I'm giving you an example. So they did the 4 similar thing that all other automatic initiations 5 that are part of Chapter 15.
6 VICE CHAIR REMPE: And even this is the 7 standard analysis that Peter --
8 MEMBER KIRCHNER: Yeah, this question 9 applies to all the instrumentation.
10 VICE CHAIR REMPE: -- has done.
11 CHAIR SUNSERI: Hey, Dinesh. This is 12 Matt. I've got a question for you. I think this is 13 accurate, but correct me if I'm wrong on this. I 14 think as the plant gets closer to getting an operating 15 license, there'll be an instrument set point and 16 uncertainty analysis that will cover all of the 17 instruments that are used in tech specs, that are used 18 in the emerging operating procedures that the 19 operators use to control the plant.
20 And that document gets reviewed by the 21 NRC, I believe. And so therefore, that's a tool 22 that's used to make sure that the operators aren't 23 relying on anything that is not capable of performing 24 within the range necessary to successfully complete 25 the action. Is that right, what I'm saying?
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160 1 MR. TANEJA: Right. So what we evaluated 2 is a set point methodology document as part of the 3 design certification. So their design certification 4 is based on a set point control program which 5 basically says that the actual values of the set 6 points would be outside of the tech specs, controlled 7 outside of the tech specs. So that program actually 8 needs to be finalized before they can load fuel.
9 So that means they have to do actual set 10 point calculations based on the installed as built 11 conditions and the actual instrument data. And the 12 numbers that they have in the set point methodology 13 documents have to be validated by actual calculations 14 that have to be performed during construction. And 15 NRC inspects those calculations as part of our high 16 tech inspection process.
17 CHAIR SUNSERI: So that seemed to be the 18 safety net that would alleviate some of the concerns 19 that are being --
20 MEMBER KIRCHNER: And also, all the 21 equipment has to be qualified --
22 MR. TANEJA: Exactly.
23 MEMBER KIRCHNER: -- and calibrated.
24 MS. TURNER: Exactly.
25 VICE CHAIR REMPE: Well --
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161 1 MEMBER KIRCHNER: Yes, and it doesn't --
2 it's not just level, Joy. It's all the sensors have 3 to be --
4 MR. TANEJA: Right, the temperature, 5 pressure.
6 VICE CHAIR REMPE: And all of these things 7 were done for the DCA early on, and we reviewed it.
8 Now we've got this additional concern. Were any 9 changes -- other than I know you changed the set 10 points on the containment water level and you added 11 this -- NuScale added the pressure initiation 12 methodology for ECCS.
13 What about reactor vessel water level?
14 Have any changes been made? Or is the staff --did 15 they look at it and say, oh, no changes needed to be 16 made because of this boron dilution issues. That's 17 where I'm trying to get to.
18 MR. TANEJA: The level instrumentation 19 uncertainties remain the same because there really was 20 not change to the consideration of any parameters that 21 would have affected that measurement.
22 VICE CHAIR REMPE: Because of the boron 23 dilution, the operators will not need any higher 24 accuracy than what's currently going to be --
25 MR. TANEJA: That --
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162 1 VICE CHAIR REMPE: -- available to them --
2 (Simultaneous speaking.)
3 MR. TANEJA: -- I don't know exactly what 4 procedures would dictate and what their allowance 5 would be on what information. The NuScale is aware of 6 what the uncertainties would be on those measurements.
7 So I think the operators know how close or inaccurate 8 those numbers would be under those conditions. And 9 they have to take that into consideration whether that 10 information would be suffice or whether they need to 11 correlate that information, corroborate that 12 information, looking at all different data that they 13 have available, temperature, pressure --
14 VICE CHAIR REMPE: And how will the staff 15 know --
16 MR. TANEJA: -- containment level.
17 VICE CHAIR REMPE: -- to be sure?
18 MR. TANEJA: Well, that really is part of 19 the EOP procedure. And that really runs into the COL 20 stage of activity, right?
21 VICE CHAIR REMPE: Absolutely. It's a COL 22 thing, but I just am wondering how the staff will --
23 is there going to be some note somewhere that will 24 tell the staff, oh, in addition to what was approved 25 on the DCA? When they finally figure out what they're NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.
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163 1 going to do for the boron dilution issue, they need to 2 think about sensors. That's where I'm wondering is 3 there something written somewhere other than in our 4 transcripts that says that, oh, they need to consider 5 that too. And I think you're agreeing with me, 6 Dinesh. You're saying --
7 MR. TANEJA: I am.
8 VICE CHAIR REMPE: -- no, that hasn't been 9 looked at yet.
10 MR. TANEJA: Right. So the EOP stage is 11 that they are developed by the COL holder, correct?
12 So the EOPs do get validated on their functionality.
13 And they have to recognize the limitation of the 14 information that they have available that they rely 15 upon to make some decisions. And right now, those 16 procedures are not there. So really, they are 17 evaluated by the staff during the construction phase 18 before the fuel load, the EOPs are looked at.
19 VICE CHAIR REMPE: Just wish we had 20 something that made me feel comfortable they would 21 look at this issue too besides all the other 22 requirements that are specified in the DCA.
23 MR. TANEJA: We --
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164 1 to the next question.
2 MEMBER KIRCHNER: Yes, let's go on.
3 MR. YARSKY: Okay. So --
4 MEMBER KIRCHNER: Peter, I think it's back 5 to you.
6 MR. YARSKY: Right. I was wondering if it 7 might be worth taking a second. I would like to 8 revisit this comment about the reactivity rate that 9 Jose had brought earlier, having had time to think 10 over the lunch break. And I think that using Jose's 11 approach or the staff's approach, we ultimately would 12 get to the same answer. I think it's just a matter of 13 perspective. So I was wondering if I could take a 14 moment to try and address that.
15 MEMBER KIRCHNER: Go ahead.
16 MR. YARSKY: So in thinking about how to 17 sort of screen some of these events, in the original 18 white paper, the staff would use linear approximations 19 and calculations to try and arrive at a figure of 20 merit that would be the time it takes to have one 21 positive dollar of reactivity. And in doing that, we 22 calculated sort of accidentally a reactivity insertion 23 rate, though we say that that's not the best physical 24 representation of the process. I agree with Jose that 25 depending on sort of what the end points are of this NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.
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165 1 calculation, you calculate a different rate.
2 So in the staff's calculation, it's 3 looking at trying to calculate the time from critical 4 to one dollar, that you add that one dollar of 5 reactivity and then translating that into a time 6 result. Using Jose's approach of looking at the 7 reactivity when you have the actual condition of the 8 reactor at highly borated and voided conditions where 9 it's deeply subcritical, you would in like, a linear 10 approximation, you would calculate a higher rate. But 11 you would have to -- in order to get the time it takes 12 to get to one positive dollar of reactivity, you would 13 be dividing by then a larger delta K.
14 And I think that we would end up 15 calculating the same number which is the number of 16 seconds to get to positive one dollar of reactivity.
17 And that's sort of the figure of merit for the staff's 18 calculation. So I think that the confusion there is 19 probably just in terms of thinking about that 20 calculation that's aimed at developing that time in 21 terms of a rate.
22 MEMBER MARCH-LEUBA: This is Jose. I 23 don't agree with you, Pete, and I want to be even more 24 nasty than that. I'm going to ask you a question.
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166 1 hunch? Is it a gut feeling or a calculation? And you 2 don't have to answer that. That was a rhetorical 3 question.
4 That's my problem. I believe -- I 5 honestly believe that if we put our heads to it and we 6 do a scientific, thorough, detailed calculation which 7 won't be easy, we could find that this design is okay.
8 But we don't design reactors and accept the safety in 9 the 21st century based on opinions, hunch, or gut 10 feelings. And that's all I'm saying.
11 I have not seen any calculation. I don't 12 see a process by which a detailed calculation will be 13 supplied by the COL applicant because if the SER is 14 published as is, it becomes a legally binding 15 document, a legally binding document that says that no 16 operator action whatsoever can possibly challenge the 17 core. Why would COL applicant embark on a multi-18 million dollar research program to contradict the 19 statement of the staff that favors them? And the COL 20 applicant cannot, we've developed some new procedures.
21 And accordingly, the staff told us that anything we do 22 is okay. So here are the procedures, and we're okay.
23 Prove me wrong.
24 MEMBER KIRCHNER: Yes. Jose, I think the 25 -- let's stop there. The point is taken, and that's NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.
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167 1 probably more appropriate for the Committee's 2 deliberations than just throwing this back and forth 3 to the staff or the applicant at this point. Can we 4 go on to the last question, Dr. Yarsky?
5 MR. YARSKY: Sure. And Question Delta was 6 about the time ranges. And as I've alluded to 7 earlier, we tried to calculated that with TRACE but 8 were not successful. And so we developed the hand 9 calculations, and I believe we discussed this before 10 lunch about the --
11 MEMBER KIRCHNER: Yes, you did, yes.
12 MR. YARSKY: -- time it takes to.
13 MEMBER KIRCHNER: And I think --
14 MEMBER PETTI: Dr. Yarsky --
15 MEMBER KIRCHNER: When you present your 16 slides, perhaps you could address this in more detail 17 again. I think your very last slide has your time 18 calculations.
19 MR. YARSKY: Yes.
20 MEMBER PETTI: Dr. Yarsky, just for 21 clarity, when you did TRACE, that was a 1D or a 22 multidimensional calculation?
23 MR. YARSKY: Three dimensional 24 calculation.
25 MEMBER PETTI: It was? Okay. Thank you.
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168 1 MR. YARSKY: Now so if it would be to the 2 benefit of the Committee, we can talk through some of 3 the backup slides. And I think that was something 4 that was raised as something that would be valuable.
5 So we could do that.
6 MEMBER KIRCHNER: Yes. Okay. Are we --
7 Mike Snodderly, let me check with you because I've got 8 a lot of things out in front of me. Have we gone 9 through all the questions that were submitted?
10 MR. SNODDERLY: I'd like to also hear from 11 the staff, but I believe you have. And if we could 12 ask Peter to share his screen and bring those slides 13 up, that would be great --
14 (Simultaneous speaking.)
15 MEMBER KIRCHNER: If we're through with 16 the questions, let's go to Peter and the backup slides 17 then. Okay.
18 MR. YARSKY: There is an additional 19 question that the staff has not addressed yet on the 20 PRA sequences. It was listed as a specific question.
21 MEMBER KIRCHNER: Okay.
22 MR. YARSKY: And so I don't know if you 23 would like to have the staff address that question 24 before going to the backup slides.
25 (Simultaneous speaking.)
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169 1 MEMBER PETTI: I think it might be better 2 to go through the slides first --
3 MEMBER KIRCHNER: First, I think so too, 4 Dave.
5 MEMBER PETTI: -- to provide more context.
6 MEMBER KIRCHNER: Yeah. Peter, since you 7 have the floor, why don't you go ahead and do those 8 slides. If you could do them crisply, I know there's 9 a lot of detail buried in there on test facilities and 10 so on. But please go ahead.
11 MR. YARSKY: Okay. Marieliz, are you able 12 to share the slides?
13 MR. BAVOL: This is Bruce. I'll take care 14 of that.
15 MR. YARSKY: Okay.
16 MEMBER KIRCHNER: Christiana, do you need 17 to make Bruce a presenter to do that?
18 MS. LUI: He's just made presenter.
19 MEMBER KIRCHNER: Okay. Thank you.
20 MEMBER BLEY: While we're waiting for the 21 slides to come up, this is Dennis Bley. For the 22 Committee, I don't want to talk about it here. But 23 I'd recommend you take a look at SECY-96-128 and 24 especially the SRM for that SECY. It's interesting.
25 One day, we might want to talk about it.
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170 1 MR. BAVOL: Can everybody see the slides?
2 MEMBER KIRCHNER: Yes, Bruce. They're up.
3 MR. YARSKY: Okay. So I'll try and go 4 through these very quickly. If we progress to the 5 first slide.
6 MR. BAVOL: Okay. I can't scroll through 7 these.
8 MEMBER KIRCHNER: Peter, I think we have 9 your first slide up with the overview of the test 10 facilities.
11 MR. YARSKY: Oh, okay. Yeah, I'm not able 12 to see that on my screen. But the idea in terms of 13 developing a response to the question was to provide 14 additional evidence of the internal recirculation flow 15 pattern, in particularly, experimental evidence that 16 that type of flow pattern and mixing could be expected 17 to occur. And in doing that literature review, we 18 identified a number of separate effects and integral 19 effects tests that we think are relevant. And this 20 sort of provides an overview of that.
21 And so this list includes, of course, 22 separate effects tests in large diameter tubes as well 23 as routed conditions and integral effects tests like 24 CCTF and SCTF and PKL. In all of these tests, there's 25 a consistent finding that there is a three dimensional NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.
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171 1 effect of void channeling and the development of 2 internal recirculation, particularly under pool 3 boiling conditions and that these conditions can be 4 expected to develop even under adiabatic experimental 5 conditions.
6 However, of all of that, I believe the 7 most compelling experiment to discuss is the PKL boric 8 acid precipitation test that was performed as part of 9 an international collaboration. And so if we could 10 skip ahead, Bruce, to the PKL slides. And these 11 backup slides do include some information about the 12 other tests and the other test facilities and the 13 findings. So I'm not able to see the slides on my 14 screen, but are we sharing the first PKL slide?
15 MEMBER KIRCHNER: Peter, what we have are 16 the three cross sections of the PWR postulated 17 scenario, PKL at SOT and PKL test results.
18 MR. YARSKY: Yeah, at the start of the 19 test, what is done is the liquid level in the 20 downcomer is lowered and the two phase level in the 21 core is lowered to uncover the hot leg. And then ECCS 22 flow into the cold leg is manual in control to match 23 the evaporation rate in the core. And this is done to 24 minimize the mixing volume.
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172 1 study boric acid precipitation. So the idea was to 2 drive the boric acid concentration to very high 3 levels. So that's the condition of the start of the 4 test. And then at the end of the test, the ECC flow 5 is increased until there's a recovery. So if we go to 6 the next slide, the next slide should show plots of 7 the boron concentration at different phases of the 8 experiment. The --
9 MEMBER KIRCHNER: That's what we're 10 looking at, Peter.
11 MR. YARSKY: Yeah, the low level stage is 12 sort of the middle of the experiment. And these 13 measurements were done with conductivity probes as 14 well as extracting samples of the fluid at discrete 15 moments in time. So they're redundant measurements 16 made of the boric acid concentration.
17 And these measurements are made above the 18 core, below core, and around the core. And what we 19 observe in the test is a relatively uniform and 20 homogeneous concentration of the boric acid in the 21 reactor whereas if this mixing was not taking place --
22 so if you were to think of it from a one dimensional 23 perspective, the boric acid concentration in the 24 bottom of the core would stay close to like 5,000 ppm 25 and the boric acid concentration of the top of the NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.
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173 1 core would continue to increase and would be much 2 higher.
3 What we see is that there's a relatively 4 uniform concentration above, below, and around the 5 core. And so I think this is sort of the most direct 6 evidence because the boric acid concentration was 7 measured in those different locations to illustrate 8 that the mixing takes place even when there is no 9 significant flow. As I said, the ECC flow here is 10 tuned just to match the boil off. So the 11 thermohydraulic condition is very similar to what 12 would be expected in the NuScale configuration.
13 (Simultaneous speaking.)
14 MEMBER BALLINGER: Peter, this is Ron 15 Ballinger. Does the size of the experiment scale well 16 with the NuScale dimensions that are important?
17 MR. YARSKY: I don't have a good answer 18 for that question, Ron. This facility is scaled to 19 look like a German convoy reactor. So of course, you 20 know, if you were to think of the -- would this scale 21 down to the NuScale configuration? One, the vessel 22 height would be all off. So if you were to think, 23 like, does this get the natural circulation right? It 24 wouldn't.
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174 1 that we're looking at, you have a pretty static level 2 of, like, the RRV-ish elevation with very stagnant 3 flow. So I think even though there is that scaling 4 distortion, I don't think that would be very 5 significant.
6 MEMBER KIRCHNER: Peter, this is Walt 7 Kirchner. I actually know this facility and worked 8 with it. This is -- to answer Member Ballinger's 9 question, its full height in terms of core height. So 10 those parts of the dimensions are about right. It's 11 obviously not full diameter of the German reactor 12 core. It was scaled more -- that's where the scaling 13 took place. But the heights roughly are correct in 14 terms of representing the primary system.
15 MEMBER BALLINGER: I guess I was more 16 concerned with the sort of downcomer dimensions and 17 things like that because are these dimensions large 18 compared to the width of, say, the downcomer in the 19 NuScale design?
20 MR. YARSKY: Well, Ron, I don't know how 21 the downcomer dimensions specifically scale. But I 22 don't believe the downcomer significantly interacts 23 with the internal recirculation. And so the ECC flow 24 is being manually controlled in the experiment. So in 25 terms of what's going on in the lower plenum, I don't NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.
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175 1 think that the downcomer scaling distortion affects 2 the results.
3 MEMBER BALLINGER: Okay. All right.
4 Thanks.
5 MR. YARSKY: There would be the question 6 of the -- like, the barrel dimension relative to the 7 riser wall dimension. But clearly in the experiment, 8 that's smaller than you would see in NuScale. And so 9 I think that you would have, like -- when the flow 10 pattern develops, you have, like, the central core and 11 then you have the periphery. I think it would just be 12 wider in the NuScale case, but I haven't done any kind 13 of specific look at the scaling distortion here.
14 The smaller the facility is, I think the 15 more scaling distortion you add. But I think it would 16 hamper the development of this flow pattern. So if 17 you get really mixing in the small diameter case, I 18 think you'd expect it to be better in the large 19 diameter case.
20 MEMBER BALLINGER: And that would go for 21 the lower plenum as well?
22 MR. YARSKY: Yes, that would go for the 23 lower plenum as well. But I don't think that the 24 lower plenum has as a significant of role to play as 25 the active core region.
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176 1 MEMBER BALLINGER: Okay, thanks.
2 MEMBER MARCH-LEUBA: Let me just offer a 3 comment. This is very promising. But as a good 4 mathematician would say, this is necessary but not 5 sufficient condition. I can show you plots of test 6 facilities where you survive a LOCA perfectly. But we 7 still analyze LOCAs. Just because there was one 8 reactor in Germany that run a LOCA simulation and the 9 LOCA was good doesn't mean we don't analyze LOCAs.
10 And I'll leave it there.
11 MEMBER BROWN: This is Charlie Brown. To 12 echo Pete's question a while ago, for those who are no 13 thermohydraulically initiated that much. You have two 14 questions. What is the relevance of the curve?
15 What's it telling us? I have no idea. I know the 16 concentration.
17 Is there a limiting concentration or is 18 there a minimal that we should? And has SOT start of 19 the transient and EOT end of the transient? And is 20 CVCS operating during this because it says so up at 21 the very top and in one of your little boxes?
22 MR. YARSKY: So Charlie, to address those 23 points, what's being measured here is the boric acid 24 concentration.
25 MEMBER BROWN: Yeah, I got that.
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177 1 MR. YARSKY: The test was to look at 2 precipitation. So the test was run specifically to 3 get to very high boric acid concentration. So you can 4 see here that this is in, like, the 20 to 40,000 ppm.
5 MEMBER BROWN: Why is that? What's the 6 nominal value you would have in the plant as it exists 7 today in the NuScale --
8 MR. YARSKY: So under sort of this 9 postulated boron dilution case, I think you're talking 10 more in the range of, like, 4,000 to 10,000 ppm.
11 MEMBER BROWN: Okay. The bottom part of 12 the graph in other words?
13 MR. YARSKY: Right. So it's certainly, 14 like, a different range of boron concentrations. But 15 the purpose of showing this test is, I think, in this 16 case because the boric acid concentration was measured 17 during the test. What I'm taking away from it is not 18 what the value of the concentration is, but the 19 relative value of the concentration of the core inlet, 20 the core outlet, and the core periphery which we can 21 see is relatively uniform.
22 (Simultaneous speaking.)
23 MR. YARSKY: So what this is indicating is 24 that it's mixing. Now the CVCS --
25 (Simultaneous speaking.)
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178 1 MEMBER BROWN: The curves -- what you mean 2 by that is the curves overlay?
3 MR. YARSKY: Right, exactly.
4 MEMBER BROWN: Okay. But I'll also ask 5 CVS is on during this, is it? Is CVCS on --
6 MR. YARSKY: Yeah, CVCS is operating in 7 the cross overlay at these specific points that I 8 marked.
9 MEMBER BROWN: Is it through the whole --
10 (Simultaneous speaking.)
11 MEMBER BROWN: -- time or is it just 12 through a certain time? I couldn't tell that.
13 MR. YARSKY: It's just for certain times 14 that are --
15 MEMBER BROWN: For five, six, and seven?
16 MR. YARSKY: -- indicated by the --
17 MEMBER BROWN: Five, six, and seven 18 brackets?
19 MR. YARSKY: I would say it's during four, 20 five, and six.
21 MEMBER BROWN: Okay. I'm looking at the 22 little boxes which say, increase by injection from 23 CVCS down at the bottom. It doesn't tell me over what 24 box it is. So you're saying it's roughly four, five, 25 and six?
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179 1 MR. YARSKY: Yeah, you can see when the 2 CVCS is on if you look at the -- do you see where it 3 says, injection with CVCS and --
4 MEMBER BROWN: Yes.
5 MR. YARSKY: -- cross overlay?
6 MEMBER BROWN: Yeah.
7 MR. YARSKY: And there's some shading 8 underneath.
9 MEMBER BROWN: Okay.
10 MR. YARSKY: That's when CVCS is 11 injecting.
12 MEMBER BROWN: That's the brownish 13 shading?
14 MR. YARSKY: No, I would call it blue.
15 It's underneath. It says, injection with CVCS in 16 crossover leg. And then immediately beneath that, 17 there's a white band with blue shading at certain 18 points.
19 MEMBER BLEY: Charlie, up at the top, 20 right under the top.
21 MEMBER BROWN: I saw that. I got that, 22 Dennis. That's why I was asking the question. But I 23 didn't know what's the white. It's not on then. It's 24 only on during the blue parts.
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180 1 in terms of the boundary condition that's key here is 2 that the -- even with the CVCS on, the ECCS flow is 3 being adjusted so that you're maintaining constant 4 inventory.
5 MEMBER BROWN: So that's not 6 representative of the NuScale --
7 (Simultaneous speaking.)
8 MR. YARSKY: Even though you have 9 injection here with ECC injection, what's happening is 10 it's maintaining a level. And so that's why I think 11 it's actually a lot like NuScale.
12 MEMBER BROWN: Okay.
13 MR. YARSKY: Because, like, you'll have 14 the steam leaving through the hot leg and then through 15 the break whereas in NuScale, that steam would be 16 condensed in containment. And that'd be kind of like 17 acting like the sump would act. See, you end up 18 having a consistent level in the downcomer. So I 19 think it's pretty analogous.
20 (Simultaneous speaking.)
21 MEMBER MARCH-LEUBA: It is analogous to 22 NuScale operation before you turn CFDS on. I mean --
23 MR. YARSKY: Yes.
24 MEMBER MARCH-LEUBA: -- you're presented 25 with a steady state operation and ECCS cooling.
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181 1 MR. YARSKY: Right. Jose, that's a very 2 good clarification. Yeah, I'm talking when there's no 3 injection. So this is just when you have just the 4 natural circulation, yeah.
5 MEMBER MARCH-LEUBA: No one is claiming 6 that the core deborates during ECCS cooling before 7 recovery. As I said, this is excellent. This is good 8 data. If you have not contained constant boron or 9 semi-constant boron concentration here, you could not 10 possibly hope to do it in NuScale. In my opinion, 11 it's not sufficient. It's promising but not 12 sufficient.
13 MEMBER BROWN: My other question, is CVCS 14 working during this -- on the NuScale during this 15 concern about deboration or is it off? Is it not 16 injecting or injecting?
17 MR. YARSKY: I think the worry --
18 MEMBER KIRCHNER: It's not. It's been 19 isolated.
20 MR. YARSKY: I was going to say I think 21 the worry is that the downcomer would dilute and then 22 at some future point in time yet undetermined, the 23 operators would begin a CVCS injection. And that by 24 virtue of that CVCS injection, that diluted water 25 would be transported into the core.
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182 1 MEMBER BROWN: It will be driven down in 2 other words?
3 MR. YARSKY: So there's a period of time 4 where there's no injection and operators are taking no 5 action. And after ECCS, the downcomer begins to 6 dilute because the core and the DHRS are acting kind 7 of like a distiller.
8 MEMBER BROWN: Yeah, I understand that 9 part of it. I was trying to figure out what role CVCS 10 played. You just told me that tends to exacerbate it.
11 If you do it early, is it positive? And if you do it 12 late, it's negative? That's what you just kind of 13 said.
14 MR. YARSKY: Well, so if the downcomer 15 dilutes and then it never transports, then it's not 16 impacting the core. If the CVCS is used in some way 17 to increase the level -- and that procedure hasn't yet 18 been established. But that would have the potential 19 to transport that diluted water from the downcomer 20 into the core. And I believe that's the synthesis of 21 the Committee's concern.
22 MEMBER BROWN: What if it started earlier?
23 Is it a procedural issue?
24 MR. YARSKY: I believe that if you -- that 25 the potential concern would be exacerbated the more NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.
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183 1 diluted the downcomer is. And so there would be a 2 timing element.
3 MEMBER BROWN: I guess my question is if 4 early in the transient, instead of waiting to actuate 5 CVCS if you did it early, is that a positive or a 6 negative effect?
7 MEMBER KIRCHNER: I --
8 MEMBER BROWN: I'm trying to figure out a 9 way to get us out of this mess.
10 MEMBER KIRCHNER: No, no. This goes back 11 to what I was saying earlier. Yes, earlier 12 intervention is better.
13 MEMBER BROWN: Well, we went through the 14 return to power thing on stuck rod, and we walked our 15 way through operator actions. They can drive the rod 16 in and do all this good stuff. And now we're sitting 17 here not taking advantage of any possible operator 18 actions that would mitigate this and allow those who 19 are concerned about return to power like I am in this 20 situation. It would allow us to accept it.
21 I'm trying to look for a way that we used 22 on the return to power for stuck rod in a similar 23 matter that you do for this circumstance. That's all 24 I was -- that's -- again, I'm not first in 25 thermohydraulics. But based on your all's NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.
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184 1 conversation for the last two hours, three hours, it's 2 been back and forth with all these nuances as opposed 3 to what can you do to fix it as opposed to extra 4 instrumentation and fixes to that and fixes to that.
5 If you can turn the stuff on early, it sounds like you 6 can possibly resolve it. I don't know if that's right 7 or not, but that's just my perception based on 8 listening to everything.
9 CHAIR SUNSERI: But Dr. Yarsky, this is 10 Matt. I just want to make sure I understand this.
11 Independent of whether you do start core flood and 12 drain system early or late or add boration to the 13 downcomer area early or late, what this data is 14 showing is that during the distillation process, the 15 boron concentration stay relatively constant. And 16 when you have CVCS injection in the crossover leg, it 17 doesn't necessarily disrupt that equilibrium that 18 much. Is that how I'm reading this?
19 MR. YARSKY: So Chairman, I wouldn't --
20 like I want to focus a lot on the CVCS injection in 21 the crossover leg in terms of interpreting the results 22 here because any injection is going to be -- will have 23 some compensation in the ECCS injection to maintain a 24 constant inventory.
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185 1 though, right, because that's what's happening in the 2 NuScale design, right?
3 MR. YARSKY: Right. And so like I would 4 instead focus in terms of the message I'm trying to 5 communicate here is that in this facility, the 6 uniformity of the boron concentration and these 7 different regions around and in the core is 8 demonstrating that there is some mixing process that's 9 ensuring that the concentration is relatively uniform, 10 even when there is very, very little total flow rate.
11 So this can only be occurring if there's some sort of 12 internal recirculation to distribute that boron to 13 maintain that relatively uniform distribution.
14 MEMBER KIRCHNER: And if I might add, Dr.
15 Yarsky. This is Walt Kirchner. Matt, this experiment 16 is part of a long series of experiments done at PKL, 17 mainly addressing ECCS performance in a PWR. And what 18 you're seeing here is as Dr. Yarsky pointed out.
19 That's of interest for -- and relevance to the NuScale 20 design is the period between four and six where this 21 is an electrically heated core.
22 So they're running it at decay heat.
23 They've got a decay heat profile, and they'll run the 24 experiment through. So you've got a thermal source 25 even under low flow rates to stimulate mixing in the NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.
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186 1 core. And so I think the takeaway here is that in 2 that band between four and six, you see from their 3 sensors that the distribution through the height of 4 the core is essentially about the same within 5 experimental error.
6 CHAIR SUNSERI: Yeah, I understand that, 7 but one more question. So what is the source of the 8 ECCS fluid? I mean, is it coming off a borated 9 source? Is it --
10 MEMBER KIRCHNER: Yeah, this is borated.
11 And what they were doing in the experiment is they're 12 running a profile, a simulation of how the ECCS 13 systems would function in a large PWR under a LOCA 14 scenario. And so you see the ramp up in boron because 15 there, the ECCS systems are injecting boron. This is 16 much higher.
17 And look at where the scale is, as Dr.
18 Yarsky pointed. This is under reflood conditions.
19 Now the boron concentration is much, much higher, 20 almost, what, a factor of well over -- well, let's see 21 -- six, seven, eight times normal concentrations. And 22 the problem that they were worried about was 23 precipitation, that all of a sudden, they would hit a 24 condition and all the boron, the boric acid would just 25 precipitate out into the lower plenum.
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187 1 CHAIR SUNSERI: Right. No, I remember 2 those concerns. But I'm just trying to make sure I 3 understand the experiment here and what the data is 4 showing me. So thanks for the explanation.
5 MR. YARSKY: Yes, absolutely. Thank you, 6 Walt.
7 MEMBER PETTI: I just had a -- I want to 8 make sure I understand it in my words. What the 9 experiment shows is that there is this internal 10 recirculation flow that mixes all the boron, even at 11 what are normally very low injection rates into the 12 downcomer that are sort of matching the steaming 13 rates, not that dissimilar from NuScale. Further, the 14 other slides that you skipped show similar 15 recirculation flows and under other conditions smaller 16 in scale. And so it's this experimental evidence that 17 you are relying on to say that mixing -- internal 18 mixing in the core and riser will occur and that a 19 wave front type physical model is just mental picture 20 to figure out what happens in this situation. Is that 21 --
22 MR. YARSKY: Yeah, so I would say that 23 we've looked at a variety of integral and separate 24 effects tests that we think are relevant that 25 demonstrate this phenomenon. And the idea of a NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.
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188 1 propagating front, we don't think that that is the 2 best physical paradigm to try and understand what 3 would occur during a flow incursion. And it would be 4 very important to consider this internal recirculation 5 driven mixing.
6 MEMBER PETTI: And so this is what's the 7 basis of not a significant reactivity excursion if the 8 water in the downcomer were to come into the bottom of 9 the core.
10 MR. YARSKY: Right. The idea is that if 11 downcomer water comes in relatively slowly that it 12 will mix and that you won't have a persistent 13 reactivity accumulation.
14 CHAIR SUNSERI: So I -- so this is -- I 15 don't want to sound too legalistic but this comment or 16 this question, it sounds to me like what we are --
17 what you're describing here is the fact that in 18 absence of a detail analytical conclusive result 19 you're using these kind of engineering analysis and 20 experimental datas relevant to the case to make a case 21 that you are reasonably assured that that's going to 22 happen in this particular reactor design and that's 23 what you're basing your decisions on. Is that saying 24 too much?
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189 1 that, you know, we have calculated the internal 2 recirculation flow pattern in TRACE and that's part 3 of, you know, what went into the -- into the white 4 paper.
5 So I would say that internal recirculation 6 is predicted by the systems analysis and I think that 7 it's supported by this experimental evidence that 8 would indicate that that pattern should physically 9 develop.
10 You know, I think apart from that there 11 are --
12 MEMBER KIRCHNER: Dr. Yarsky?
13 MR. YARSKY: Yeah.
14 MEMBER KIRCHNER: Can I add something 15 here? This is Walt Kirchner. Matt, to his, Dr.
16 Yarsky's, comment about TRACE, TRACE actually run in 17 the 3D mode would do a reasonable job of predicting 18 recirculation patterns.
19 What we heard about before lunch was 20 tracking boron because of numerical dissipation, which 21 is a different problem. But as far as predicting 22 mixing patterns in an open core like this, TRACE would 23 do a reasonable job of predicting that kind of 24 phenomena.
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190 1 if my question was too overly simplified here. I 2 mean, you know, in the global analysis, right, we 3 don't have the full systems-based analysis that 4 describe how the boron mixes and what the reactivity 5 insertion rates are and all that stuff.
6 But we would be more comfortable, if you 7 will, if we knew that there was good mixing going on 8 coming into this core, based on everything else we 9 have heard about and know about this core.
10 If we knew -- if we had better assurance 11 about that, that would help us alleviate a lot of our 12 other concerns at this time. That's all I am trying 13 to say.
14 And so what we are using this analysis 15 here to give us that somewhat assurance that there's 16 going to be reasonable mixing going on here.
17 MR. YARSKY: Right, and I think that's a 18 very good point and I would like to stress this is 19 that, you know, when you're using systems analysis 20 it's very important to understand, you know, what the 21 limits of that analysis are.
22 I mean, you still have a computer code 23 that you're exercising and you still need to interpret 24 the results that are coming out of it, and while I 25 believe research was comfortable with the idea of NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.
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191 1 using TRACE to predict this internal recirculation 2 pattern and can substantiate, you know, with this 3 experimental basis why that internal recirculation 4 flow pattern is real, there are other problems with 5 using systems analysis to try and do a full-blown 6 tracking of the boric acid concentration 7 redistribution.
8 You know, and we have tried to use TRACE 9 to look at some of the committee's question in more 10 detail but run into, you know, some issues where it 11 looks like numerical considerations can introduce 12 these artificial perturbations that sort of compound.
13 Then it becomes difficult to use systems analysis to 14 answer some of these questions in a more direct way.
15 MEMBER BALLINGER: Peter, this is Ron 16 again.
17 Is it your judgment that any scaling 18 errors that might exist between the NuScale design and 19 this experiment are sufficiently, what do you want to 20 call it, small so that these results are not 21 invalidated by scaling errors?
22 MR. YARSKY: So, Ron, in my opinion, the 23 scaling distortion is going to be introduced by the 24 diameter of the barrel and I believe that the scaling 25 distortion would result in the experiment predicting NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.
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192 1 a less uniform distribution than you would expect in 2 the prototype.
3 MEMBER BALLINGER: So you're also saying 4 that the ratio between, say, convective and 5 diffusional and other mass transport mechanisms are 6 about the same?
7 MR. YARSKY: Right. So the -- you're 8 going to have -- so, like, the way those are going to 9 scale is going to be by height and power density and 10 those are relatively similar. I mean, they are not 11 exactly the same but you're not talking about a factor 12 of two scaling. You're talking, like, the percentage.
13 MEMBER BALLINGER: Okay. Now, within the 14 core --
15 MR. YARSKY: The scaling distortion here.
16 MEMBER BALLINGER: -- their fuel, if I 17 recall, is just standard, I think, AREVA fuel. It's 18 got flow trippers in its cross flow. But the fuel 19 design itself doesn't introduce mixing errors between 20 the two experiments?
21 MR. YARSKY: I am not the greatest expert 22 about how the heater rods were designed for PKL. But 23 I am under the impression -- and, I mean, Walt will be 24 able to correct me if I am under the wrong impression.
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193 1 height and to look like a commercial PWR fuel product.
2 MEMBER KIRCHNER: Yeah, and they used 3 commercial spacers, if I remember correctly. So it's 4 very similar to the German fuel and that's not that 5 different under these flow conditions. The mixer --
6 the mixing veins that are the -- kind of the black art 7 of spacer grids --
8 MEMBER BALLINGER: Yeah.
9 MEMBER KIRCHNER: -- which each fuel 10 supplier develops help with things like critical heat 11 flux at very high flow rates and such. But these --
12 here we are looking at a reflood flow rate measured in 13 inches per second or less, and --
14 MR. YARSKY: Yeah --
15 (Simultaneous speaking.)
16 MR. YARSKY: -- if you think about it.
17 MEMBER KIRCHNER: -- so it's an open --
18 it's an open -- it's just an open -- how should I say 19 it? These are not ducted like a BRW. It's an open 20 lattice, and so they are prototypical mixing grids, 21 prototypical size rods.
22 So the first order of things like cross 23 flow and such under reflood conditions would be very 24 similar hydraulically to that of the actual reactor.
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194 1 just trying to get a handle on any sources of error.
2 MEMBER BLEY: This is Dennis Bley. This 3 morning when you introduced your physical description 4 you talked about working up a characteristic timing 5 for the introduction of reactivity increase in a 6 characteristic time for mixing, and, roughly, can you 7 tell us those characteristic times? You've given us 8 a lot of stuff to look at and I am -- I can't say that 9 I've digested it all yet.
10 MR. YARSKY: Yeah. So we calculated the 11 internal recirculation flow pattern with TRACE and 12 derived a mixing time of about 40 seconds. And so 13 what we tried to do in the original white paper was to 14 calculate the amount of time it would take to have 15 inserted enough reactivity to reach positive one 16 dollar of reactivity, and in that calculation, of 17 course, we assumed, like, it's a propagation of a 18 front, you know, develop this reactivity insertion 19 rate to calculate these timings.
20 And so for CFDS injection with both trains 21 operating, when we calculated that time it was I think 22 about 80 seconds.
23 MEMBER BLEY: Okay. Thanks.
24 MR. YARSKY: Or no, it was 39 seconds.
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195 1 comparable to the mixing time.
2 MR. CORRADINI: So, Peter, this is 3 Corradini. Both trains means you would only need one 4 train or you would expect not to do more than one 5 train at a time, right? But you assume both trains 6 are operating at full flow?
7 MR. YARSKY: Right. So it's sort of like 8 the max. We looked at CVCS injection and CFDS 9 injection and, like, what could give you the most --
10 like, the most oomph.
11 The most oomph is going to be from both 12 CFDS trains operating together and when we looked at 13 that, that amount of time it would take to get the 14 positive one dollar was about 40 seconds, which is 15 comparable to the mixing time.
16 MEMBER MARCH-LEUBA: If we have any 17 questions, can I ask a process question, Peter?
18 Based on your -- on your judgment on --
19 so hand calculations, the staff has written an SER and 20 is about to publish it that says no operator action 21 whatsoever can possibly cause damage to the core.
22 I believe there's expectation of -- I 23 mean, I find that -- I just thought that conclusion a 24 little unconvincing because it's not thorough enough 25 or detailed enough.
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196 1 The expectation of some of the members 2 I've talked to is that during the COL phase we will 3 actually do more work to ensure that these carefully 4 -- these hand calculations are correct.
5 But we will have an SER which is a legally 6 binding document that says the operator can do 7 anything they want but nothing will happen.
8 What will prevent a COL from developing 9 the best procedures they can come up with and say, we 10 are not going to do an analysis because the staff told 11 us that these procedures are good because anything 12 that the operators can do is good?
13 And I don't see what if occurs -- I mean, 14 if the staff at the time still remembers that this is 15 an issue, an issue in REI, saying what will happen if 16 the COL can work with the SER and say, you already 17 looked at it and Peter said nothing happens. Why do 18 you want me to spend a million dollars for a testing 19 facility to do this.
20 MR. YARSKY: Yeah. So, Jose, I think this 21 is a really good point and this is something that in 22 the white paper we did include some verbiage to try 23 and sort of think about this issue.
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197 1 confidence in operators that if they wanted -- if they 2 purposefully wanted to damage their core that they 3 could come up with a sequence of actions, adverse 4 actions, that they could take that could do that.
5 You know, and I might not be creative 6 enough to think of what those actions are but a 7 competent qualified operator I think would have enough 8 knowledge to do something like that.
9 But I don't think it's reasonable to 10 postulate the malicious operator assumption.
11 MEMBER MARCH-LEUBA: Oh yeah. Nobody's 12 talking about sabotage here.
13 MR. YARSKY: Right. So I think it's --
14 well, it's -- well, they tried to consider in the 15 scope of the white paper what we consider to be, like, 16 reasonable assumptions about potential operator 17 actions, and I think that, you know, I will have to 18 defer to NRR who, of course, drafts and writes the SE 19 based on the information provided by research.
20 But if the language is as strong as 21 there's no postulated operator action, that language 22 might be -- might be too strong and maybe worth taking 23 another look at.
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198 1 have the procedures, you know, what reasonably might 2 an operator do.
3 MEMBER MARCH-LEUBA: The SER will become 4 a legally binding document in about a month or two.
5 Says there is no possible operator error of commission 6 that would cause core damage and it's based on one PKL 7 test that is not even close to what's happening when 8 you turn SER on and your gut feeling that surely, we 9 have to mix, and my gut feeling is that the COL 10 applicant is not going to spend a million dollars on 11 its product when they have a legally binding document 12 that tells them that they can do anything they want 13 with their procedures.
14 MEMBER DIMITRIJEVIC: Jose, can you give 15 me reference and then where does it -- you said the 16 19.4. -- I did not find that. I did not run into this 17 and I am trying to find it now in SER. What was the 18 section?
19 MEMBER MARCH-LEUBA: You have to look at 20 the new version of the Chapter 19, the one with the 21 changes -- track changes.
22 MEMBER DIMITRIJEVIC: Not the -- not the 23 -- okay. Not the one from December but the new one?
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199 1 this is not something, oh, that they forgot to change.
2 It's something they added on purpose.
3 I mean, I just -- tell me why, somebody 4 from the staff. I mean, let's not beat around it.
5 Somebody from the staff tell me why the COL applicant 6 will now come back and develop some procedures, the 7 ones they want to develop because they are the 8 cheapest to implement, and they will say, I don't have 9 to analyze anything because the staff told me I could 10 do anything I wanted, and it's in this legally binding 11 document. Tell me why you want to do that.
12 MR. YARSKY: Jose, if you'll give me a 13 moment, I will confer with the staff for a second 14 because I don't think I am the right person to address 15 this question.
16 CHAIR SUNSERI: Let me -- let me jump in.
17 I don't think that's a fair question to ask the staff 18 because it's asking -- it's asking the staff to 19 speculate what an applicant might do and that's not 20 their job.
21 So their job is to, you know, apply the 22 regulations and that's what they are doing. They 23 can't speculate of how an applicant might want to use 24 or misuse whatever authority they've been given.
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200 1 an SER they should evaluate how this SER will be 2 implemented. What is the consequence of the staff's 3 actions? I mean, I know it's not fair. I know it's 4 malicious. I know it's a question you don't want to 5 answer. But this --
6 CHAIR SUNSERI: I think we are ignoring a 7 lot of the other checks and balances that go into the 8 licensing process. This design certification is not 9 a license.
10 There's going to be all kinds of 11 additional approvals necessary before this reactor get 12 operated. They are going to have to write the EOP, 13 emergency operating procedures. They are going to 14 have to validate those procedures.
15 The regulator is going to review those 16 procedures. There's going to be systems that design 17 is going to be completed on that hasn't been 18 completed.
19 The NRC is going to review those things.
20 There are a -- there is -- this reactor is so far from 21 being licensed that I think, you know, to say that --
22 I think that's the reason why these procedures are 23 vague to us right now because the design has not 24 progressed along to do that.
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201 1 questions that we can't answer -- the questions that 2 we ask now that can't be answered will be answered 3 later and the licensing process, the COL applicant and 4 the NRC's review of that application will address 5 those at that time.
6 MEMBER KIRCHNER: Peter, this is Walt 7 Kirchner again.
8 Do you want to show your last view graph 9 of this set or are you finished at this point?
10 MR. YARSKY: We will leave that to the 11 discretion of the committee. I am happy to talk about 12 the timing calculation that's represented in the last 13 slide. But I think it's only worth the committee's 14 time if the committee thinks it's worth the time.
15 MEMBER KIRCHNER: Well, just please 16 explain what we have in front of us on that last slide 17 so the committee understands what was done.
18 MR. YARSKY: Okay. So if we go to the 19 final slide it says timing of downcomer dilution, and 20 this was to address the specific question delta, and 21 in these calculations we -- first, we attempted to use 22 TRACE.
23 But as I alluded to in the post-ECCS 24 period, we were getting what we believed to be 25 nonphysical results for downcomer boron concentration.
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202 1 So instead we relied on TRACE to calculate 2 everything up to the point of ECCS and this is where 3 we get the time of ECCS actuation. We were able to do 4 a nominal actuation at 1,700 seconds for a small break 5 LOCA and then delayed the actuation by lowering the 6 RPV pressure subpoint to, first, 600 psi and then 500 7 psi, and by delaying the ECCS the initial 8 concentration in the downcomer was lower at the point 9 of ECCS actuation.
10 Then from that point, there would be 11 flashing that would increase the downcomer 12 concentration. But we have conservatively did not 13 credit that.
14 Then for decay heat power levels, we 15 translated that to a steaming rate, and based on that 16 steaming rate we were able to perform a hand 17 calculation for the amount of time it would take 18 starting at that given boron concentration and given 19 that steaming rate how long it would take to reach two 20 fixed concentrations.
21 The first is 100 ppm and the second is 10 22 ppm, and this corresponds -- I mean, not exactly but 23 kind of roughly to about 90 percent dilution and 99 24 percent dilution.
25 MEMBER KIRCHNER: Thank you.
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203 1 MEMBER MARCH-LEUBA: Just for reference, 2 the CBC, critical boron concentration, is not 90 3 percent dilution. It's a proprietary number because 4 they gave it to us prior to presentation but you guys 5 know the answer. It's not 90 percent dilution.
6 MR. YARSKY: Right. Right. So, Jose, 7 this is -- this shouldn't be -- these numbers should 8 not be construed to say this is when you get critical 9 boron concentration.
10 So we didn't -- so we did not provide what 11 the numbers are relative to critical boron 12 concentration on this slide. But if you know what the 13 critical boron concentration is you can see how that 14 value compares relative to the initial concentration 15 and it only goes down from there in our hand 16 calculation.
17 So we don't credit the concentrating 18 effect of flashing. So, hopefully, you know, if you 19 know that critical boron concentration you'll see why 20 we then report that time.
21 MEMBER KIRCHNER: Members, further 22 questions of Dr. Yarsky?
23 MEMBER PETTI: Walt, I just want to thank 24 him. I thought these slides were, I think, important 25 for us to hear to understand the thought process of NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.
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204 1 the staff, both the first white paper and now the 2 second white paper, and how they got to their 3 reasonable assurance finding. It helped me a lot.
4 MEMBER KIRCHNER: Yeah. Thank you, David.
5 Yes, thank you, Dr. Yarsky, and also Ryan 6 Nolan. Thank you for responding to our questions.
7 Okay.
8 MR. YARSKY: Could I then pass the baton 9 to the NRR staff to address the final question --
10 MEMBER KIRCHNER: Yes, please.
11 MR. YARSKY: -- that was specific to the 12 PRA? I believe that Marie posed that question.
13 MEMBER KIRCHNER: Yeah, who's the PRA 14 question?
15 MS. POHIDA: Thank you, Pete. May I 16 begin?
17 MEMBER KIRCHNER: Yes, go ahead, please.
18 MS. POHIDA: Why, thank you. I am looking 19 at bullet one and the scenario of concern that we 20 partially discussed this morning is a small break 21 LOCA, and the scenario is a LOCA inside containment 22 with or without a successful reactor trip. An ECCS 23 fails and CVCS injection succeeds.
24 And so the questions are, you know, that 25 we -- the staff received is does the PRA slide 33 from NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.
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205 1 the staff's presentation cover this? Is this -- is it 2 based on a calculation on engineering judgment?
3 Okay. Now, for these scenarios, for both 4 of these scenarios, CVCS injection is needed to 5 prevent core damage from inventory loss.
6 When the staff reviewed these scenarios, 7 you know, based on Peter Yarsky's white paper, CVCS 8 injection following an ECCS failure does not cause a 9 reactivity insertion that could cause core damage, 10 based on Dr. Peter Yarsky's mixing discussion that was 11 presented this morning.
12 Does that answer everybody's question?
13 MEMBER KIRCHNER: Marie? Marie, this is 14 Walt Kirchner.
15 In that scenario where ECCS has failed, 16 then the pressure of the system is higher. I don't 17 know exactly when you decide CVCS is injected. But 18 the pressures are higher. Is that true?
19 MS. POHIDA: It's --
20 MEMBER KIRCHNER: In other words, you've 21 got a small break LOCA. You're depressurizing the 22 primary. You're losing inventory to the containment.
23 You're on some kind of decay heat curve and you are 24 slowly depressurizing the primary system and losing 25 inventory.
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206 1 MS. POHIDA: Yes. We are considering that 2 ECCS fails upon a legitimate demand around 900 pounds.
3 MEMBER KIRCHNER: Yeah. So that's the set 4 point, the nominal set point. Here's the concern that 5 I would raise and ask whether this was looked at.
6 Peter broke up his analysis of these 7 events into two categories. One he called transient 8 and the other prolonged, and it was the transient --
9 the quick transients that were the more plausible way 10 of rapidly introducing deborated water into the core.
11 So if the CVCS system trips and injects 12 colder water, doesn't that rapidly have the effect of 13 either making the riser swell and/or depressurize the 14 system, which would lead to void formation, all of 15 which would then introduce a surge of water into the 16 core?
17 MR. YARSKY: So, Walt, this is Peter 18 Yarsky from the staff.
19 We thought about this. If the CVCS 20 injects into the pressurizer, so you turn on 21 pressurizer spray, of course, that can lead to 22 depressurization and flashing and level swell.
23 But the amount -- like, the pressurizer 24 spray is not going to be as good at depressurizing the 25 vessel as opening the RVVs. So the idea is if the RVV NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.
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207 1 opening case does not result in core damage, then the 2 pressurizer spray case will be bounded by that.
3 So I hope that that sort of addresses the 4 question with regards to pressurizer spray.
5 MEMBER KIRCHNER: But the RVD, if I might 6 pursue this, is like a LOCA in and of itself and 7 that's a slower depressurization, isn't it? Or 8 faster?
9 MR. YARSKY: Well, the choking flow 10 through the RVVs --
11 MEMBER KIRCHNER: Is it faster?
12 MR. YARSKY: If you open the RVVs you 13 should -- it's going to be like large break LOCA.
14 You're going to depressurize relatively quickly. So 15 it's going to be more severe than using pressurizer 16 spray.
17 MEMBER KIRCHNER: And so your argument 18 about the --
19 [Simultaneous speaking) 20 MR. YARSKY: -- the RVV opening sequence 21 you don't need to analyze the pressurizer spray 22 sequence because it will be bounded.
23 So the pressurizer spray can lead to all 24 the phenomena that we are talking about. It just 25 won't be as bad as RVV opening.
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208 1 So we are not saying it doesn't need to be 2 considered. It's just you don't need a separate 3 calculation. You can just use the RVV opening 4 calculation because it's bounding.
5 MEMBER KIRCHNER: And what is your 6 assumption at that juncture of -- so you're assuming 7 that the boron concentration or that there hasn't been 8 any significant boron dilution in the downcomer?
9 MR. YARSKY: Well, if you --
10 MEMBER KIRCHNER: Because of either the 11 holes or just the --
12 MR. YARSKY: Yes. So the other thing we 13 considered is, like, yeah, let's say you do somehow, 14 like, get the RVVs open, right, and then you 15 depressurize and so the level drops down and so then 16 you can dilute the downcomer and then you turn on 17 pressurizer spray.
18 If you turn on pressurizer spray later 19 after RVVs are open, it's going to be kind of like an 20 "oh, never mind" because you're starting from such a 21 low pressure at that point that the level swell effect 22 is going to be really muted.
23 MEMBER KIRCHNER: Okay.
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209 1 because you've diagnosed that as ECCS failure. Then 2 the resultant flow incursion is not as severe as would 3 have had occurred if the RVVs opened.
4 So we just didn't identify it as a 5 different -- as something that needed to be analyzed 6 because it would be bounded.
7 And then if you looked at, well, maybe 8 ECCS does actually and then somewhere later on you 9 turn on pressurizer spray once you get a level swell, 10 well, yeah, you will. But the pressure is really low 11 so it's going to be mild.
12 MEMBER KIRCHNER: Thank you.
13 MR. YARSKY: The other concern is CVCS 14 injection into the riser and that can collapse voids 15 and cause a transient flow incursion and that's 16 something that we did look at.
17 MEMBER KIRCHNER: Marie, I apologize. I 18 interrupted you. Have you anything further to add?
19 MS. POHIDA: No, not on the sequence. If 20 I might continue with the second bullet.
21 MEMBER KIRCHNER: Yes, please.
22 MS. POHIDA: Thank you.
23 Okay. The second bullet concerns a CVCS 24 charging line break outside of containment and this is 25 not an ATWS scenario, and the sequence in question is NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.
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210 1 number five and it's a CVCS charging line break 2 outside a containment. There is a successful reactor 3 trip. However, containment isolation fails.
4 DHRS succeeds and only one train is 5 needed. But now, given the design change, ECCS is now 6 necessary for the operators to inject using CFDS to 7 prevent core damage. And the time -- we are in open 8 session but the time for the operator to inject using 9 the cavity flood and drain system is minutes.
10 So that scenario is not long enough to 11 cause significant downcomer decoration.
12 MEMBER DIMITRIJEVIC: What do you mean 13 minutes? Minutes after what?
14 MS. POHIDA: Let's see.
15 MEMBER KIRCHNER: Marie, did you hear 16 Vesna's question? It was minutes -- minutes after 17 what. Where are you measuring minutes from?
18 MS. POHIDA: The minutes after -- I am 19 looking here at my charts, and I am mindful I am in 20 open session so that I am thinking slowly here.
21 It's -- this is the time after ECCS is 22 demanded and it's -- it's minutes. If specific times 23 are needed, I request to go to a closed session 24 because it is proprietary information.
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211 1 specific numbers or just --
2 MEMBER DIMITRIJEVIC: I not need specific 3 numbers but there is an operator action associated 4 with this.
5 This is an important scenario because the 6 containment is bypassing the same time. So we are 7 talking about the large releases. So the thing is 8 that here the operator action for this activation of 9 the containment flood is just your usual 40 minutes 10 three, you know, AGP and if this is some action which 11 has to be performed in the minutes that's not 12 described anywhere. So I am not sure are we talking 13 about the same thing.
14 MS. POHIDA: This action was evaluated in 15 the staff's SER in the Phase IV SER that was finalized 16 in January -- this action. This operator action --
17 this operator action is classified as risk 18 significant. This action of being able to use CFDS to 19 prevent core damage and it is evaluated in our SER.
20 MEMBER DIMITRIJEVIC: So is it a human 21 error probability change now for this action, given --
22 I mean, that will be very high probability of, you 23 know, 0.1 or something which has to be performed in 24 such a short time, and not like 14,000 which is 25 currently.
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212 1 MS. POHIDA: You know, in terms of the 2 timing chain I am going to have to either defer to 3 NuScale or to provide this information to you -- get 4 back and provide this information to you.
5 I am looking at the times now. It's just 6 that we are in open session.
7 MEMBER DIMITRIJEVIC: Okay.
8 MS. POHIDA: But I would be happy to 9 provide that information to you.
10 MEMBER DIMITRIJEVIC: Okay.
11 MS. POHIDA: But the action of defeating 12 the containment isolation logic and using CFDS for 13 injection is described in the PRA and our SER.
14 Does that help answer your question?
15 MEMBER KIRCHNER: Vesna --
16 MEMBER DIMITRIJEVIC: Well, yeah, it does 17 -- it answers partially my question. I mean, you 18 know, the -- this moment I am sort of lowering my 19 expectations.
20 So I have to think about this. And, 21 actually, I get information from you because now 22 suddenly we have important human actions, which was 23 never identified in the -- in the Chapter 19 and also 24 we have -- we have the different discussed timing for 25 the actions which will really, you know, render the NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.
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213 1 probabilities, however, maybe not to be valid. I have 2 to -- you know, when you give me additional 3 information I have to think about that.
4 So, basically, your response to this, if 5 I can summarize, if you ever have tripped the CFDS it 6 has to be just minutes after the ECCS.
7 MS. POHIDA: I think the word minutes is 8 causing confusion. I would like to provide specific 9 times. But I believe that we need to go to closed 10 session.
11 MEMBER DIMITRIJEVIC: Okay.
12 MS. POHIDA: But thank you. That -- if 13 there are no other questions, that concludes the two 14 bullets of the ACR's questions that were provided to 15 the staff.
16 MEMBER KIRCHNER: Marie, could I -- I 17 don't want to push you into a position that you're not 18 comfortable with. This is Walt Kirchner.
19 MS. POHIDA: Thank you.
20 MEMBER KIRCHNER: When you say minutes, 21 are we saying less than an hour?
22 MS. POHIDA: I think I -- you know, either 23 I defer to NuScale or we go to closed session.
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214 1 a question. If you could just provide the information 2 to us through Mike Snodderly we would be much obliged.
3 MS. POHIDA: I would be happy to do that.
4 Thank you.
5 MEMBER KIRCHNER: Okay. I think we are 6 through with the questions that the committee 7 submitted. Is that correct, Mike Snodderly? I may 8 have --
9 MR. SNODDERLY: Yeah. I think --
10 MEMBER KIRCHNER: -- I cut Mike off. I am 11 sorry.
12 MR. SNODDERLY: That's okay. You know, 13 after Peter corrected me I went back and looked.
14 Yeah, those are the two specific scenarios that Vesna 15 asked be addressed and those have been addressed. And 16 so now I think -- I think NuScale had requested to --
17 MEMBER KIRCHNER: Yes.
18 MR. SNODDERLY: -- provide some additional 19 information.
20 MEMBER KIRCHNER: Okay. So from NuScale 21 are we turning to Mike Melton or -- I'll turn to 22 NuScale to introduce their information.
23 MR. MELTON: Thank you, all. It's Mike 24 Melton. I was -- just come off mute so I am all good.
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215 1 to go through some topics, just high level points 2 related to our post-event repair and restart procedure 3 development, a little bit of touch on our capability 4 in intermode 4. We have some comments on reactivity 5 balance and then some conclusions.
6 So, with that, I'll let John Fields sort 7 of kick us off.
8 He's our LPM for the topic, introduce our 9 presenters, and then we will read some points after 10 that. So let's go for it and, John, if you're off the 11 mute you can introduce our presenters and get us 12 going.
13 MR. FIELDS: Good afternoon. This is John 14 Fields. I am licensing project manager with NuScale.
15 Can you hear me okay?
16 MEMBER KIRCHNER: Yes, John. We hear you.
17 Thank you.
18 MR. FIELDS: Okay. So I am going to cover 19 the regulatory framework for procedure development, 20 specifically, operator procedure -- operational 21 procedure development from the design certification 22 application up to construction of startup.
23 In the design certification application, 24 the applicant provides the design of the facility.
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216 1 operating license item or items documenting procedure 2 development requirements are defined in the DCA.
3 NuScale complies with this by discussing 4 a procedure development program in DCA Section 13.5.
5 For operations procedures, NuScale COL Item 13.5-2 6 requires a description of normal operations, abnormal 7 operations, and emergency operations procedures.
8 COL Item 13.5-5 augments the COL Item 9 13.5-2 with the requirement that the COL applicant 10 provide a schedule for development and implementation 11 of these procedures.
12 As it relates to boron redistribution in 13 FSAR Sections 4.3.1.5, 15.0.4, 15.0.5, and 15.0.6, and 14 tech spec basis 3.3 address the potential for boron 15 redistribution to occur during extended passive 16 cooling conditions.
17 These sections also describe the 18 acceptability of plant design changes (audio 19 interference) to verifying boron concentration and 20 adjusting the concentration if necessary.
21 At the COL stage, operating and emergency 22 operating procedures are established prior to fuel 23 load. The purpose for this is to, quote, "allow 24 adequate time to develop operator license 25 examinations," end quote, which the NRC will review, NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.
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217 1 and that comes from SRPs 13.5.2.1 and 13.2.1.
2 Finally, the regulatory framework has 3 modified over time to also include more guidance for 4 the development of strategies for addressing beyond 5 design basis events.
6 These include regulatory requirements for 7 severe accident management guidelines, extensive 8 damage mitigation guidelines, and most recently, the 9 diverse and flexible coping strategies, or what's 10 known as flex strategies.
11 So the main takeaway from this discussion 12 is that NuScale is compliant with the regulatory 13 requirements and operations procedures of all types --
14 normal, abnormal, emergency -- and these guidelines 15 for beyond design basis events will be developed by 16 COL applicants and reviewed by the NRC prior to 17 completion of startup and operation of a NuScale power 18 module.
19 Are there any questions on that?
20 MEMBER MARCH-LEUBA: Yes, there are.
21 John, is there -- in that framework you're reading for 22 is there any requirement that the COL applicant 23 provide a safety analysis demonstrating that those 24 procedures are adequate to the (audio interference) 25 Is there any expectation that we --
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218 1 MR. FIELDS: Certainly, anything --
2 certainly, anything that departs from the VCA, the 3 approved and codified design requires NRC approval 4 again.
5 MEMBER MARCH-LEUBA: Right. But the SER 6 said you can -- the operator can do anything they 7 want, and as long as the operator is doing anything 8 they want you're not departing from the CVA and, 9 therefore, would there be any -- would you expect the 10 CVA --
11 MEMBER KIRCHNER: Jose -- Jose, can I 12 interrupt you? We are on the public record. I don't 13 think the FSER says the operator can do anything he 14 wants or she wants.
15 We need a little more precision here.
16 Point out the section and the problem you're having.
17 But the FSER does not say what you're interpolating.
18 MEMBER MARCH-LEUBA: The FSER says there 19 are no possible operator errors of omission or 20 commission that will damage the door in these 21 circumstances.
22 MEMBER DIMITRIJEVIC: Jose, can you point 23 to the page? I have SER in front of me with the 24 changes. Can you just point -- you said the section 25 was 19.146 and then I didn't write at the time what NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.
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219 1 was the next. So what is the section? Can you point 2 to the page where it says that?
3 MEMBER MARCH-LEUBA: I would have to look 4 at it. I mean, I don't have it. I moved to a 5 different section. So I will -- I will look at it 6 after I am talking about.
7 MEMBER DIMITRIJEVIC: All right.
8 MEMBER MARCH-LEUBA: But, definitely, 9 Vesna, as you are in the form. Can you confirm that 10 the PRA does not include any operator errors of 11 commission --
12 MEMBER DIMITRIJEVIC: Yes. Yes. That's 13 through -- it states actually explicitly in the PRA 14 that there is no -- identified errors of commission is 15 important and also it states that errors of sabotage 16 are not considered.
17 MEMBER MARCH-LEUBA: Correct. So there is 18 -- an error of commission means the operator made a 19 mistake and pulled the wrong switch and operated the 20 wrong equipment.
21 What PRA says is he can pull all the 22 switches in there he wants and he cannot make that 23 error because there is no error of commission. That's 24 what the PRA says. And the SER says, yes, we agree.
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220 1 procedures, they will develop the procedures.
2 They will be thorough and careful and they 3 will do the most logical procedures they can find.
4 But I don't see any requirement that they will have to 5 do safety analysis to go beyond the hand waving that 6 we have seen today. That's what I see.
7 MEMBER KIRCHNER: Marie, would you like to 8 interject a comment. I see you've unmuted your mic.
9 MS. POHIDA: No, I didn't have a specific 10 comment. If there's a question addressed to me, can 11 it be restated, please?
12 MEMBER KIRCHNER: No. No, there wasn't a 13 question. There was a statement made by a member of 14 the committee. I just saw that you popped up on my 15 screen. I thought you wanted to make a comment. It's 16 okay.
17 MR. FIELDS: If there are no further 18 questions, I'll turn it over to Ben Bristol to talk 19 about our design capabilities.
20 MEMBER MARCH-LEUBA: Ben, hold on a 21 minute. I need to give a number to Vesna. The new 22 section is 19.1.4.6.4 and it's on page 19-33 of the 23 compare -- version 4 versus 6 compare of Chapter 19.
24 MEMBER DIMITRIJEVIC: All right. Thanks.
25 The page in point, 19.33?
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221 1 MEMBER MARCH-LEUBA: Yeah. Page 19-33, 2 but this is the version of it that has track changes.
3 So it might be different from --
4 MEMBER DIMITRIJEVIC: I have the same 5 version with the track changes and it's a good 6 section. So that must be the paragraph in the end of 7 it right? That's where it states the commission 8 thing? Okay. Thanks. I will just read it now.
9 MEMBER MARCH-LEUBA: The one I am more 10 opposed to is when it says -- in the next to the last 11 paragraph. It says, "Therefore, the staff finds, dot, 12 dot, dot, that the misoperation of CFES, dot, dot, 13 dot, is not a significant risk contributor."
14 Okay. Unless you have more questions, 15 Vesna, then you can go ahead and continue 16 MEMBER KIRCHNER: But, Jose, just for the 17 record, I can't let this go. That doesn't -- that 18 doesn't equal that the FSER says the operator can do 19 anything he or she wants.
20 MEMBER MARCH-LEUBA: It is different.
21 It's a different paragraph. This is the one in the 22 CFES.
23 MEMBER KIRCHNER: I am just making this 24 statement for the record.
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222 1 section that says there are no operator errors of 2 commission that are considered in the PRA.
3 MEMBER KIRCHNER: That may be accurate.
4 They didn't consider them. That doesn't say the FSER 5 says the operator can do anything he or she wants. I 6 am just objecting to your interpolation of what you're 7 reading on the public record.
8 MEMBER RICCARDELLA: For the record, it's 9 extrapolation, not interpolation.
10 MEMBER KIRCHNER: Thank you, Pete.
11 [Laughter.]
12 MEMBER KIRCHNER: Okay. Let's go to Ben 13 Bristol, please.
14 Ben, good afternoon.
15 MR. BRISTOL: Yes, good afternoon. So I 16 am here to cover for a little bit of the system 17 capabilities from the plant perspective.
18 As Ryan covered, I thought, pretty well 19 this morning the scope of Chapter 15, which is mostly 20 my area, leaves us with a deterministic analysis of 21 the design basis event and in them -- in quotes, 22 "safe and stable condition" and I want to put on the 23 record, NuScale believes that boron accumulation in 24 the core is very beneficial.
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223 1 that enhances the -- or reduces the likelihood of 2 stuck rod return to power consideration. So we do not 3 believe the characterization of the degraded condition 4 is actually true.
5 The importance of the boron is where it is 6 relative to the core now. That does mean that boron 7 is transported from containment and, potentially, is 8 a downcomer as discussed quite a bit over the last 9 several weeks, and as part of that process.
10 So one result is careful consideration 11 needs to be taken in terms of reestablishment of the 12 levels in the containment and in the RCS that are 13 consistent with most boron.
14 We recognize that an event will not result 15 in a restart and require repairs and those are of, I 16 think, specific interest in this particular 17 conversation.
18 So in terms of the recovery actions from 19 the potential LOCA events where we, potentially, 20 disabled the CVCS and the ability to inject, I think 21 we have discussed why injection over the core and 22 recirculation through the downcomer with letdown 23 allows -- excuse me, allows us to actually monitor 24 what the boron concentration is in the system.
25 I think one of the -- the two primary NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.
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224 1 considerations that I'd like the members to consider 2 is that, one, boron addition can be performed in a 3 batch mode, right.
4 So we can -- we can inject, based on 5 procedure, a specific amount, wait and monitor the 6 conditions. I thought Peter did a good job explaining 7 that the neutron monitoring system does have the 8 capability of evaluating gross reactivity changes. So 9 operators are not completely blind with respect to 10 where we are in terms of criticality.
11 So I think that's the -- the first point 12 is that systems don't just -- don't have to be turned 13 on and left on, right. We can -- we can inject 14 certain amounts -- specific amounts of borated liquid.
15 The other real important consideration is 16 that the coolant addition is always colder than the 17 RCS temperature conditions. The boron addition system 18 is maintained at approximately full temperatures, sort 19 of in the 100 -- the 50 to 100 degree range depending 20 on environmental conditions and what the plant is, and 21 that will -- that will always ensure that whether we 22 are injecting into the riser or the downcomer that 23 will preferentially mix and that if mixing doesn't 24 occur that the boron will -- the borated water will 25 settle toward the bottom of the RCS and not present a NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.
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225 1 stratified manometer injection type phenomena.
2 MEMBER MARCH-LEUBA: Ben?
3 MR. BRISTOL: So the third thing I --
4 MEMBER MARCH-LEUBA: But a couple of 5 things. First, I interrupted you. Let me go to the 6 previous one. You meant -- you said that increasing 7 the boron concentration in the core is beneficial for 8 the stacked rod return to power.
9 I am glad you think so, but this is an end 10 of cycle condition where your ppm is 10 ppm. If the 11 boron concentration goes from 10 ppm to 20 and, 12 therefore, is irrelevant to the stacked rod condition 13 -- I mean, it's beneficial. It's not that -- let's 14 say it's not detrimental, but saying it's beneficial 15 is a little bit of an overstatement.
16 Second, what would the -- what is the 17 temperature of the downcomer? The downcomer is 18 connected through the wall of the containment through 19 the UHS pool and this -- it's been there for 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br />.
20 It's not done much hotter than the UHS.
21 What is the temperature of the downcomer 22 fluid at 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br />? Because you're taking credit for 23 it being hotter than the injected CFDS liquid which, 24 by the way, was in the containment, not the downcomer.
25 So, if anything, it would fall down at the NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.
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226 1 bottom of the containment it was so cold. So and 2 that's why I keep saying that one thing is moving your 3 hands and saying things look my way. Another thing is 4 doing a full analysis.
5 Keep going.
6 MR. BRISTOL: Sure. So and what I am 7 attempting to do is provide some basic physical 8 arguments, and I'll get into the relevance of 9 temperature after this next point.
10 With respect to the CFDS, and I am glad 11 you brought that up, the containment flood drain 12 system has a very important feature, which is we can 13 actually drain the containment.
14 So in the event that we have the ECCS 15 cooling conditions for a period of time and do not 16 necessarily know what the containment boron 17 concentration is, we can actually drain the 18 containment prior to refilling it with cool 19 concentration, which definitely -- which ensures that 20 operators have a possible procedure that could be 21 followed where without having to measure the 22 concentration we would know exactly what the core 23 concentration is if we were to relate the containment 24 concentration is if we were trying to reestablish 25 levels through CFDS alone.
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227 1 So I think in terms of walking through a 2 couple of the scenarios, if we had a discharge line 3 failure as a consideration then we wouldn't 4 necessarily have the ability to sample the downcomer 5 concentration.
6 But we do have injection capabilities. So 7 if operators were able to diagnose the discharge line 8 failure was the event initiator, a potential procedure 9 could look something like draining the containment, 10 refilling it with -- and after the containment is 11 drained injecting to the core and that will push the 12 downcomer water back into the containment, at which 13 point it can be sampled and that process can be 14 repeated in a batch mode until we actually know what 15 the concentration is in the downcomer because we have 16 the ability to measure it.
17 In the case of an injection line failure 18 -- I think this is one that we have spent some time 19 talking about -- pressurizer spray can be aligned and 20 I would remind the committee that the pressurizer 21 baffel plate has eight holes that are uniformly 22 distributed around the radius of the vessel.
23 So through the containment spray we can 24 actually inject borated water into the downcomer 25 directly, spilling over the generator tubes and I NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.
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228 1 think that's where the importance of the temperature, 2 the injected temperature, is relevant.
3 If we are injecting in the downcomer we 4 want to ensure that it mixes, right, because we don't 5 want a stratified layer entering the core, 6 necessarily.
7 Obviously, once the level is increased 8 then we can pull off of the discharge line and sample 9 what the concentration is, and because the core is in 10 a cooled state there is no time pressure for this and 11 we can monitor it, like we said, with the NMS.
12 And I think, finally, the final 13 consideration there is for some reason CVCS is 14 completely unavailable. We can drain the containment, 15 refill it with cool water, which will be colder, and 16 that will ensure that the recirculation water through 17 the reactor recirc valves is colder than the downcomer 18 and will preferentially mix and, again, that 19 procedure, if we were to do it, would be handled very 20 slowly and be monitored carefully because that's the 21 one where mixing would be -- would need to be ensured 22 in terms of ensuring that we weren't having an 23 inadvertent reactivity excursion.
24 So just a quick summary of what we 25 covered. The slow controlled injection of colder NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.
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229 1 borated water directly into the downcomer can be 2 engineered in the event of the loss of the ability to 3 inject above the core to ensure that recovery actions 4 can establish the module back into the normal 5 operating state without risk of an inadvertent 6 criticality.
7 MEMBER MARCH-LEUBA: Okay. So this is 8 fantastic. This is really good, man. I mean, 9 finally, through my unrelenting efforts, you guys 10 finally have spent a couple of days trying to think 11 how this would be done.
12 I can find a lot of problems, like I found 13 with your stacked rod return to power. This is 14 something that should probably be reviewed 15 aggressively.
16 For example, how does the containment-17 draining system work? Doesn't it work by producing --
18 MR. BRISTOL: So the specifics there are 19 we would use the containment evacuation system to 20 pressurize probably with nitrogen or some 21 noncondensable. Both ECCSes actually at this point.
22 Once the system is pressurized to some --
23 to some point -- I don't know the exact specifics of 24 atmospheric conditions -- then the drain line can be 25 opened up and we can pull the liquid out the bottom of NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.
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230 1 the containment vessel.
2 MEMBER MARCH-LEUBA: So you would 3 pressurize the top of the containment to push the 4 water out?
5 MR. BRISTOL: Correct.
6 MEMBER MARCH-LEUBA: And what effect would 7 that have on downcomer and riser?
8 See, that is the type of thing that one has to 9 work through and actually simulate. Let a computer 10 calculate it and see if it's good or bad. Certainly, 11 depressurizing would be really bad.
12 VICE CHAIR REMPE: How long does such a 13 process take, just roughly? A day? An hour? Two 14 days?
15 MR. BRISTOL: I think -- I think the 16 process -- I think the key point from NuScale at this 17 point is that because we have the inventory and 18 established cooling in the core and, you know, just 19 passive decay heat removal, these procedures would be 20 event specific and they would be planned out.
21 We have a couple of statements regarding 22 that coming up here in a few minutes. But I think for 23 the purposes of the discussion today, I think NuScale 24 heard some of the conversation about, you know, the 25 system capabilities and I was -- I am not really here NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.
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231 1 to get into the specifics of exactly what the 2 procedure would be.
3 But we do have -- with the systems that we 4 have in the plant, we do have a variety of ways that 5 we could recover in the unlikely event that something 6 happened to CVCS.
7 MEMBER KIRCHNER: Ben, this is Walt 8 Kirchner. Just a question of clarification. When you 9 say inject in the downcomer, you're really saying 10 inject into the pressurizer and drain into the 11 downcomer, correct? You can't use the letdown line as 12 an injection point. Or can you?
13 MR. BRISTOL: Yeah, that's -- so the 14 pressurizer spray line is lined up on the injection 15 side.
16 If we had an injection line break inside 17 containment we could line the pressurizer spray up 18 with the bypass valve and then -- yes, exactly like 19 you said, we can add coolant to the pressurizer and 20 let it drain down into the downcomer.
21 MEMBER KIRCHNER: And the holes for the 22 control rod guide tubes in the baffel plate, those are 23 -- that's a relatively tight fit so that there's no 24 preferential draining into the riser? It's 25 preferential draining into the downcomer?
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232 1 MR. BRISTOL: Correct.
2 MEMBER KIRCHNER: Okay. Thank you.
3 MEMBER MARCH-LEUBA: Ben, if you had to 4 because both pressurizer line and the transient line 5 didn't work, and you just have access to the downcomer 6 line, you could revolve your CVCS or, worst case 7 scenario, get a plumber with a welding torch and put 8 the new pump -- and put boron through it? You could, 9 right? If you had to.
10 MR. BRISTOL: Certainly, and I think there 11 are examples in industry under severe accident 12 conditions where there's quite a bit of creativity 13 that is applied to ensure, you know, the movement of 14 materials after an accident.
15 MEMBER MARCH-LEUBA: We have had this 16 argument internally. What I am saying is if you have 17 to -- that would not be your preferred option but if 18 you had to, you could use that?
19 MEMBER KIRCHNER: Yeah, but the existing 20 -- you know, sticking with the DCA, the existing 21 plumbing layout for CVCS does not provide for that 22 contingency.
23 I mean, do you see what I am asking, Ben?
24 I just want to -- that was my question of 25 clarification. There's no way with the existing CVCS NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.
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233 1 system as laid out in the DCA in Chapter 9 that you 2 would be able to inject through the letdown line.
3 That's a one directional line. Isn't that correct?
4 MR. BRISTOL: Yes, I believe there's a 5 check valve along the way.
6 MEMBER KIRCHNER: There's a check valve, 7 yes.
8 MR. BRISTOL: But certainly if we were 9 getting creative then, you know, we would figure out 10 --
11 MEMBER KIRCHNER: I know, but, I mean --
12 MR. BRISTOL: -- a way.
13 MEMBER KIRCHNER: Cutting plumbing and so 14 on, I don't think is in the scope of a DCA review.
15 MR. BRISTOL: Thank you, sir.
16 MEMBER MARCH-LEUBA: So with a view of 17 what I've been trying to say all along, this was very 18 good. Finally you guys thought about what possible 19 things you could do.
20 Don't you think that was worth -- maybe 21 not in there per se. Maybe it's a white paper 22 submitted during an audit to allow this stuff to see 23 in an audit.
24 MR. BRISTOL: So I think that question is 25 directed to me. I would say at this point, I mean, NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.
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234 1 NuScale is certainly committed from a business 2 perspective to support customers well beyond just this 3 one licensing activity. So it is important to us 4 obviously to ensure that we have the technical 5 capacity to understand these problems and these 6 challenges and support future licensing endeavors.
7 But I think we absolutely discussed a fair 8 amount the specific that the specifics of these 9 procedures fit within the framework of the design 10 phase that we're within. But we do have capacity 11 within the systems to develop creative processes to 12 ensure that safety is always ensured and is a top 13 priority.
14 MEMBER MARCH-LEUBA: And may I assume that 15 your final COL PRA would then include operator errors 16 of commission if the sophisticated, complex recovery 17 procedures are not followed perfectly? And you can 18 see a new world, Mike, when my computer tells me my 19 device has poor operator quality. I'll --
20 MR. MELTON: Yes. This is Mike Melton, 21 manager for licensing. At this point, I'd like us to 22 not make any speculation on that and let our next 23 slide presenter proceed.
24 MEMBER KIRCHNER: Go ahead, Mike.
25 MR. MELTON: Thank you, sir. That would NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.
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235 1 be Mr. Ross.
2 MR. SNUGGERUD: Can you guys hear me?
3 MEMBER KIRCHNER: Ross, you're just a 4 little muffled, just speak up or more closely to your 5 mic.
6 MR. SNUGGERUD: Yes, sir. Is this better?
7 MR. MELTON: There you go.
8 MEMBER KIRCHNER: Yes, that's better.
9 MR. SNUGGERUD: Thank you. All right.
10 Well, I appreciate the time and chance to speak. My 11 name is Ross Snuggerud. I'm the Chief Engineer for 12 Operations.
13 And I just have kind of a summary 14 statement on NuScale's position regarding the state of 15 the reactor after accidents. And I'd like to read 16 through it. It's less than half a page. And then 17 I'll take any appropriate questions after that.
18 It is recognized as a result of the work 19 performed by NuScale and the review provided by the 20 NRC staff that the operation of passive safety systems 21 in a NuScale power module provide an extraordinary 22 level of protection to the reactor fuel.
23 These systems prevent fuel damage over a 24 large range of accident conditions. The NuScale plant 25 provides this level of protection for an extended NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.
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236 1 period of time without the need for additional water, 2 a source of power or operator actions.
3 It is also recognized that when these 4 passive systems are used, a re-distribution of boron 5 within this module may occur. As a result, 6 restoration actions must consider these conditions and 7 ensure that work done to place the module in a 8 condition that supports entry into Mode 4 is done 9 safely.
10 The flow path available to operators and 11 the instrumentation provided with the module provides 12 sufficient means to support the owner in taking these 13 steps.
14 NuScale can support the owner, the COL 15 applicant, in developing procedures that implement 16 actions to return the facility to normal operation 17 where the impact of the event and the status of plant 18 equipment can be anticipated, for example, in a loss 19 of feed water event.
20 These procedures will have entry 21 conditions that ensure the plant conditions are 22 consistent with assumptions made during the 23 development of the restoration process.
24 But consistent with industry practice, 25 these procedures will not address all potential NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.
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237 1 restoration scenarios from all potential accident 2 conditions.
3 It is likely that the procedures needed 4 for restoration from scenarios like those discussed by 5 the ACRS last week and this will be developed after 6 the event with the oversight of the NRC.
7 These restoration procedures will take 8 into account current plant conditions, available 9 instrumentation, existing water levels, required boron 10 concentrations, appropriate flow rates or batch 11 volumes and any other factors that impact safe 12 restoration of the power module.
13 The advantage of the NuScale design, in 14 contrast to those facilities currently operating in 15 the industry is that while these actions are being 16 planned, the module will remain safe without the need 17 or support of any active safety systems.
18 It is NuScale's position supported by the 19 staff's review that there is ample margin for 20 restoration actions to be performed safely.
21 MEMBER KIRCHNER: Is that it, Ross?
22 MR. SNUGGERUD: Yes. That's the end of my 23 prepared statement.
24 MEMBER KIRCHNER: Okay. Thank you. Just 25 a question of clarification. You have used a term NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.
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238 1 just a little bit different than we've been talking 2 about. We've generally been talking about recovery 3 from these design basis events. And you're talking 4 about restoration.
5 Is the implication of that word that 6 you're out in a longer time period and actually doing 7 interacting --
8 (Simultaneous speaking.)
9 MR. SNUGGERUD: No. The choice is 10 intentional because we feel like recovery implies that 11 the state that you're currently in is unstable or 12 unsafe. And we don't believe that's true.
13 So as an operator, and the way the 14 emergency operating procedures will be developed, 15 we're going to be monitoring critical safety 16 functions. And when those critical safety functions 17 are met, we're in a position where we're not going to 18 take any actions that we aren't positive will result 19 in an improvement of the situation.
20 So if your safety functions are met, which 21 they are in Chapter 15 for us by design, then as an 22 operator you're not in any hurry to do anything until 23 you're sure the action you're going to take is going 24 to improve the condition of the reactor.
25 So we chose to call that restoration just NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.
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239 1 because we thought that there was some connotation 2 associated with recovery, but functionally we're 3 probably talking about the same thing.
4 MEMBER KIRCHNER: Okay. Thank you very 5 much. Yes.
6 MEMBER MARCH-LEUBA: Hey, can I ask you a 7 question? I've been measuring always a transfer to 8 Mode 4 because that's when you have to do the 9 restoration so you can move the module to the computer 10 station.
11 But the moment you lose CVCS, for example, 12 or I suspect in most situations, you will A, start de-13 borating the cover, B, you would likely lose your 14 boron measurements limitation. But you will also drop 15 below 420 degrees Fahrenheit. So you will go from 16 Mode 2 to Mode 3 on temperature.
17 And the operator will either measure 18 whether the water concentration is too low and 19 inconsistent with Mode 3 or will be incapable of 20 misreading it, which will put you in an LCO.
21 What would an operator do when he's an LCO 22 that says that he cannot determine what the bottom 23 concentration is?
24 MR. SNUGGERUD: So the LCO is applied to 25 pre-accident conditions. The reason for the LCOs is NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.
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240 1 to ensure the reactor, prior to an accident, is within 2 the design basis of the calculations.
3 So it's understood that should you 4 experience an accident, you will find yourself in a 5 condition that doesn't match your LCO conditions.
6 Part of the reason for calling the procedures 7 restoration procedures is you're going to start the 8 process of putting the plant back to within the tech 9 specs so that you can continue forward on recovery and 10 return to service or maintenance or those types of 11 things.
12 And we believe for the vast majority of 13 the types of scenarios that we're talking about when 14 we are operating for a long period on passive cooling 15 that the systems and components available to the 16 module will be sufficient to support doing that.
17 It may take a while. We may choose to do 18 small batches and wait. It could take suction. And 19 we may even have to use separate equipment if there 20 has been damage to the module that wasn't anticipated.
21 But in all cases before you can transition 22 into Mode 4 and before you can pick the module up, 23 you're going to have to re-establish boron 24 concentrations within the Mode 4 capabilities or 25 you're going to be asking for special permission from NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.
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241 1 the staff if there's some reason why you couldn't do 2 that and you wanted to proceed to the refueling area.
3 And in that case you're going to be 4 explaining to the staff why that's a safer option than 5 finding a way to meet the requirements.
6 MEMBER MARCH-LEUBA: So you're saying that 7 under these safe and stable conditions with ECCS 8 operation, you don't have to satisfy the tech specs 9 mostly?
10 MR. SNUGGERUD: You're not in the LCO 11 action if you've had an event.
12 MEMBER MARCH-LEUBA: Okay. Let's not 13 argue about it. But some of these situations are 14 purposely performing, for example, when you went into 15 refueling. But let's ignore that.
16 MR. SNUGGERUD: I don't disagree with you.
17 The goal of the operating staff is going to be to get 18 the module to Mode 4. But there's no hurry. There's 19 no emphasis on trying to do that at any kind of speed.
20 It's going to be done when it can be done safely.
21 If there aren't any other questions, we 22 have another presentation by Etienne looking at the 23 reactivity balance.
24 MEMBER BLEY: This is Dennis Bley. I have 25 to sneak in one word. I hear a lot of hair splitting NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.
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242 1 about how operators will behave often by people who 2 are analysts and engineers and very good ones at that 3 but not operators.
4 Operators respond to the current situation 5 to their training, especially the most recent 6 training. This particular scenario is in the range 7 that probably won't be trained on a lot.
8 But when operators get in a spot, things 9 pop in their heads, and they sometimes respond. We'll 10 get to the procedures eventually. But the optimism 11 isn't always well-placed, and there's a whole world of 12 operating experience examples by which we can show you 13 that.
14 MR. SNUGGERUD: Yes. And I understand 15 your point. But I was a licensed senior reactor 16 operator for 10 years. And I helped put the training 17 program together for our ISV program at NuScale. And 18 one of the things about the NuScale design that is 19 unique is if the containment isolation valves work as 20 designed, the public is safe.
21 And the only way as an operator that 22 you're going to put the public at risk is to open one 23 of those valves. So in our procedures when we did the 24 training and when we did the scenario that involved 25 the beyond design-based accidents that required NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.
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243 1 operators to open containment, you know, we put 2 special things into the training. We put special 3 things into the procedure.
4 Again, all of those things are emblematic 5 of what we expect an operating plant to do, but the 6 nature of trying to operate 12 reactors, understanding 7 what your safe conditions are and what your unsafe 8 conditions are, operators are very much trained these 9 days to not take actions when unsure.
10 And the one they're going to be sure of is 11 if the containment isolation valves are closed, the 12 public is protected. So I do think it's reasonable to 13 assume that those operators are not going to be taking 14 any actions in any kind of swift, unprepared manner 15 that are not in accordance with written procedures to 16 upset a module that is in a safe condition.
17 MEMBER BLEY: I admire your confidence.
18 Go ahead.
19 MR. SNUGGERUD: I appreciate your 20 skepticism, and I understand it.
21 MEMBER DIMITRIJEVIC: Can I add something 22 on the containment? Because there is a two LOCA 23 switch outside the containment, you know, charging 24 line and (audio interference) which are -- so there 25 are two events in this case, which lead directly to NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.
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244 1 unisolated containment.
2 MR. SNUGGERUD: And I tried to reference 3 those, and I agree with you. And in those cases, I 4 would argue that your containment isolation has 5 failed.
6 And in those cases we have demonstrated 7 and developed procedures that show how a COL applicant 8 could train their operators to address those beyond 9 design basis accidents that involve containment 10 bypass.
11 And when we did that, we made a big deal.
12 There's special alarms in the control room, in our 13 emblematic control room, and there was special actions 14 that the crew had to take. Everybody on the crew had 15 to agree that opening containment was the correct 16 action.
17 Again, that's NuScale performing ISV to 18 support our staffing plan and to support the people 19 who were doing the human factors engineering 20 evaluation. But that's the same kind of logic and 21 training we are going to offer any COL applicant that 22 is interested in a NuScale plant. And they should be 23 interested in getting it from us since we put so much 24 effort into developing it.
25 MEMBER MARCH-LEUBA: Hey, did you train NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.
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245 1 your operators to respond to a failed CVCS injection 2 line LOCA? Did you ever run that LOCA with it?
3 MR. SNUGGERUD: So I don't -- well, I know 4 we ran that LOCA. I don't know -- I don't remember --
5 MEMBER MARCH-LEUBA: How do you recall --
6 MR. SNUGGERUD: -- running that LOCA 7 during ISV. We didn't do recovery.
8 MEMBER MARCH-LEUBA: Sorry, excuse me, 9 restart.
10 MR. SNUGGERUD: We didn't do restart of 11 that unit. We got it to the safe, stable condition 12 and left it at that position.
13 MEMBER MARCH-LEUBA: Two months ago, how 14 would you have restored?
15 MR. SNUGGERUD: How would we have 16 restored?
17 MEMBER MARCH-LEUBA: You have to recede a 18 VS before draining containment.
19 MR. SNUGGERUD: We don't have an operator.
20 Sorry.
21 MEMBER MARCH-LEUBA: Yes. Okay. It was 22 rhetorical.
23 MR. SNUGGERUD: And I understand that.
24 But my point, the way these would be addressed is you 25 would sit down, look at the conditions that caused you NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.
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246 1 to be in the situation that restoration was necessary 2 and evaluate your options, put together a plan, vet 3 that plan with engineering, take it to your site's 4 safety analysis review group, take it to your site's 5 overall safety -- I mean, there's lots of things that 6 would happen.
7 NuScale is the design organization not the 8 operating organization. But the operating group 9 within NuScale would expect that situation to be 10 handled the same way that all post-LOCA situations are 11 handled in existing plans. There are not procedures 12 for post-LOCA.
13 You know, if I had been on ECCS and 14 containment spray and I had emptied my SER W tank and 15 I'm on recert from the sump, there isn't a procedure 16 for how you get out of that. What you do is you 17 assess the things that you're ready for.
18 MEMBER MARCH-LEUBA: So if you have a --
19 one moment. I'm moving my phone. You go ahead. I'm 20 sorry. You don't want to hear that.
21 MR. SNUGGERUD: So, you know, again we're 22 talking about things that the COL applicant is going 23 to deal with. NuScale is confident that there is 24 equipment available in a safe place to restore a plant 25 from all of these conditions where a path to cooling NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.
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247 1 has an operating for a long time.
2 There are ways that are better than 3 others. And we will be there to support the owner if 4 and when that becomes necessary. But, you know, I'm 5 talking in circles at this point, and I'd like to pass 6 it off to Etienne.
7 MEMBER KIRCHNER: Okay. Let's transition 8 to Etienne, who is, I believe your PRA person.
9 Etienne, can you hear me?
10 MR. MULLIN: Yes, I can hear you. Can you 11 hear me?
12 MEMBER KIRCHNER: Go ahead, please. May 13 I ask other people to turn off their mics because 14 we're getting feedback in the system.
15 MEMBER BROWN: Walt, are there slides or 16 is this just talk?
17 MEMBER KIRCHNER: I don't know. Etienne?
18 MEMBER BROWN: I haven't seen any slides 19 for the last four or five people.
20 MEMBER KIRCHNER: I think basically we 21 have oral presentations, Charlie.
22 MEMBER BROWN: I just wanted to confirm 23 that I wasn't missing anything. Thank you.
24 MR. MULLIN: So this discussion is going 25 to be a little bit of a step back with respect to NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.
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248 1 talking about the potential consequences of a somewhat 2 adverse operator action, the one that you were talking 3 most about, which is just the operator injecting CFDS, 4 turning it on and forgetting about it, which I think 5 as we've discussed clearly is not what would be the 6 recommended course of action and would likely be 7 violating procedure.
8 And I want to be clear that it is 9 NuScale's position, and it is supported by the staff, 10 and we've discussed this to a large extent today, that 11 at the loop front moving through the core in this 12 scenario and ultimately encompassing the whole core is 13 physically unreasonable.
14 However in postulating this scenario, I 15 wanted to make some comments about the conditions in 16 the core that would balance the reactivity insertion 17 from completely de-borating it.
18 It was described in a meeting two weeks 19 ago in a letter provided to NuScale, and I believe the 20 staff in advance of that meeting, that there are no 21 feedbacks physically possible that could compensate 22 for the potential reactivity insertion from completely 23 de-borating the core.
24 And I wanted to describe that that is not 25 the case. And we can even go through a very simple NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.
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249 1 exercise of evaluating the reactivity balance under 2 these scenarios using publicly available information 3 in the FSAR, specifically Table 4.3-4. I don't know 4 if you all have that available or if that was provided 5 in advance of this meeting.
6 MEMBER MARCH-LEUBA: I can find it. I'm 7 looking for it now.
8 MEMBER KIRCHNER: Go ahead, Etienne. We 9 can always check that. We can pull up the FSAR.
10 MR. MULLIN: So it's a relatively simple 11 calculation and unfortunately I don't have it listed 12 in front of you so you'll have to bear with me as we 13 walk through it verbally.
14 But the first thing you have to calculate 15 is the potential reactivity insertion from completely 16 de-borating the core at the beginning of cycle 17 conditions.
18 Dr. March-Leuba this morning described a 19 10 PCM per PPM boron width coefficient so we can use 20 that for the purposes of this. And starting with a 21 beginning of cycle boron concentration of 1,235 PPM or 22 so that gives us 12,000 to 12,500 PCM of positive 23 reactivity insertion.
24 Now I will note just for context that that 25 is on its own less than the control rod worth here, NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.
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250 1 which is 14,414 PCM. And that's just for, I guess, a 2 piece of reference.
3 Now at the beginning of cycle, according 4 to this table, our net margin to critical in long-term 5 shut down is 5,099 PCM. So the difference between 6 that is the reactivity that would have to compensated 7 for the thermohydraulic conditions or fuel temperature 8 or all these other reactivity feedbacks.
9 So that leaves us about 7,300 PCM or so 10 that needs to be compensated for by some sort of a 11 feedback if we were to assume a completely de-borated 12 core.
13 MEMBER MARCH-LEUBA: Can you specify what 14 temperature you propound to state?
15 MR. MULLIN: This is -- in long-term 16 shutdown we're looking at I think 70 degrees 17 Fahrenheit conditions at core.
18 So I think the best way to do this 19 calculation using the information that's available to 20 us right in front of us is to use the moderator 21 cooling PCM value here under Table 2C.
22 Now this value provides the integrated 23 moderator reactivity feedback between shutdown 24 conditions and hot operating conditions. So between 25 70 degrees Fahrenheit and 545 degrees Fahrenheit.
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251 1 For reference, importantly, the coolant 2 density difference between these two conditions is 3 approximately 25 percent. So to get the moderator 4 density coefficient or moderator void coefficient for 5 the totally de-borated core, it's most useful to look 6 at the end of cycle value in this table.
7 And that's equivalent to the moderator 8 cooling value you'll get when there's no boron in the 9 water, which will be greater than when there is boron 10 in the water. And you can see between cold shutdown 11 and hot operating conditions, that's 5,886 PCM. So 12 that's almost all that we need.
13 So you could extrapolate or interpret this 14 as approximately a 25 percent void fraction would get 15 you mostly to a balanced reactivity. And you can 16 extrapolate from 25 percent up to approximately 30 17 percent to get you to 7,300 PCM you need to balance 18 the reactivity.
19 So in summary, this very simplified 20 calculation. It demonstrates that you can get to a 21 balance reactivity with approximately 30 percent or 22 less void in the core and that's 0 credit for boron, 23 of course, 0 credit for xenon, 0 credit for fuel 24 temperature or power defect and actually 0 credit for 25 moderator temperature. We're just crediting moderator NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.
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252 1 void.
2 So the purpose of that was just to show --
3 and this is kind of an abstract scenario and quite 4 physically unreasonable to get to these large void 5 fractions and not have an extreme amount of mixing.
6 But it just demonstrates that it's not so much 7 reactivity insertion that you have to assume that the 8 core will be melted.
9 MEMBER MARCH-LEUBA: So, Etienne, can you 10 point me to the section in the FSAR or a supporting 11 document where this calculation was performed before 12 we raised the question?
13 MR. MULLIN: No, it's not in the FSAR.
14 MEMBER MARCH-LEUBA: Okay. So because I 15 raised it, you finally did the calculation. But you 16 have done it in your head, and you knew it was 17 possibly a problem, right?
18 MR. MULLIN: Sorry. What? I couldn't 19 hear you. I knew it couldn't possibly be a problem?
20 MEMBER MARCH-LEUBA: Sorry. It's a 21 rhetoric, satirical question. Okay. What I'm 22 complaining about is the lack of scientific rigor in 23 this analysis. You need to seek out these problems by 24 yourself before you submit it to the staff for review 25 because what I'm thinking right here is things that NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.
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253 1 Jose was hearing you and then he forced you to do the 2 calculation, maybe they're okay. Let's just say 3 you're okay. What else did they miss? They didn't 4 think of this. They didn't do this calculation. They 5 just ignored it. And that's --
6 MR. MULLIN: I don't believe a fully de-7 borated BOC core is physically reasonable. That's why 8 this calculation was not included in the FSAR.
9 MEMBER MARCH-LEUBA: Well, our calculation 10 -- you do calculations from RAI 80930 show at least 15 11 cubic meters of fully de-borated peak width in an out 12 cover. And an additional, I don't know, 5, 6 cubic 13 meters in there above that are being in containment.
14 That's what your calculations show. And 15 it might be that certainly now that we have thought 16 about it, we want to develop procedures, complex 17 procedures, in which you have a probability of failure 18 by the operator, that that will make sure this does 19 not happen. But we've got to raise the question.
20 Okay. That was a rhetorical thing. Yes, you keep 21 going. You did okay job.
22 MR. MULLIN: That's all I wanted to talk 23 about. Thank you.
24 MEMBER KIRCHNER: Thank you, Etienne.
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254 1 Melton. We're wrapping up our discussion points --
2 MEMBER KIRCHNER: Thank you.
3 MR. MELTON: -- the last few points to 4 close out. First of all, the staff review has been at 5 the highest level of detail. And they have pushed us 6 and actually challenged us in a number of areas. So 7 through that we have continued to challenge our own 8 design.
9 Overall, NuScale is highly committed to 10 plant safety and providing a passively safe design.
11 The NuScale design is capable of safely returning the 12 nuclear power module to servicing all design basis and 13 end state possibilities described in the FSAR. And we 14 believe that is adequately described through a ton of 15 discussions and work as we responded to the NRC 16 questions.
17 NuScale's policies and procedures govern 18 design and engineering activities with safety as its 19 primary objective. And I think as Ross clearly 20 stated, that is our ultimate objective as we go 21 through the licensing phases.
22 So, Walt, Mr. Chairman, we appreciate the 23 time to make additional clarification points during 24 this session.
25 So I turn it back. We are concluded.
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255 1 MEMBER KIRCHNER: Thank you, Mike Melton 2 --
3 MEMBER REMPE: Walt?
4 MEMBER KIRCHNER: -- and NuScale. Members 5 of the Committee, any further questions?
6 MEMBER REMPE: Walt?
7 MEMBER KIRCHNER: Yes, I hear someone 8 calling.
9 MEMBER REMPE: This is Joy. I was 10 wondering, Ben Bristol had some interesting 11 suggestions of what could be done. And I think it 12 would -- I'm guessing he just didn't come with this 13 off the top of his head. He has a write-up.
14 Would he be willing to send that write-up 15 to Mike Snodderly so he could share it with us to 16 assist us so we don't misquote anything because we 17 won't have the transcript as we prepare our letter?
18 Would that be of help?
19 MR. MELTON: Yes. This is Mike Melton 20 with NuScale. If there's a request, we would have to 21 run that through Mr. Snodderly and go from there. We 22 can't make any statements at this point.
23 MEMBER REMPE: Sure.
24 MR. SNODDERLY: So as long as NuScale 25 realizes that whatever you submit to us, this is an NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.
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256 1 open transcript, and it will be added as part of the 2 record of the transcript and be publicly available.
3 MEMBER REMPE: And it would be anyhow.
4 I'm just asking if we could have it a bit earlier than 5 before the transcript is processed.
6 MR. SNODDERLY: I'm just making sure Mike 7 understands that, you know, if he does submit it to us 8 for me to share it, you know, it would become part of 9 the record and it would be added to this transcript.
10 MR. MELTON: Right. I understand that.
11 I will get with the staff and go from there.
12 MR. SNODDERLY: Thank you.
13 MEMBER REMPE: Thank you.
14 MEMBER KIRCHNER: Yes. Thank you, Mike.
15 Members, before we transition one more time back to 16 the staff for, in fairness, any comments from them and 17 turn to the public, any specific questions on what you 18 just heard from NuScale?
19 Okay. With that, Mr. Chairman, I think we 20 will now turn back to the staff just to provide them 21 an opportunity to make any further comments if they 22 wish to.
23 So I'm not sure who to turn to, Bruce 24 Bavol or Anna Bradford, any further comments, or 25 Michael Dudek, that you wish to make at this point?
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257 1 MR. BAVOL: This is Bruce Bavol, project 2 manager. If the staff doesn't have any further 3 questions, I appreciate the time this afternoon that 4 we were able to provide input. That's all we have.
5 MEMBER KIRCHNER: We appreciate what you 6 provided. Thank you and thank your colleagues. Thank 7 you very much.
8 MR. DUDEK: So this is Michael Dudek. I 9 echo Bruce's sentiments. I would like to make one 10 minor clarification at the end.
11 The staff does now have an NLO from ODC on 12 Chapters 15, 6 and 19. We did not have those NLOs 13 during the earlier meeting in July. And I promised to 14 tie back to the Committee on when we got those.
15 The only things that were noted in those 16 from OGC were editorial updates. No technical content 17 was changed.
18 MEMBER KIRCHNER: Michael, for the record, 19 would you tell the public what an NLO is.
20 MR. DUDEK: No legal objection. It is the 21 standard to which OGC reviews and approves the SERs.
22 MEMBER KIRCHNER: Thank you, Michael.
23 Okay. Thanks to all the people who participated. I 24 think, Mr. Chairman, we should turn to any public 25 comment and then we'll turn to our colleagues, I NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.
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258 1 think, for any comments they want to make.
2 I just want to note that once we 3 transition from this part of our program, we will go 4 off the record, the public record and the transcript, 5 and we will be deliberating as a committee.
6 And at that juncture then, any 7 interactions with the applicant and the staff will be 8 more in the vein of asking for clarification and such 9 but not active debate and participation in our letter 10 preparation.
11 So this is a good juncture for any 12 comments or any input. Otherwise, I think we now 13 could turn to the public.
14 CHAIR SUNSERI: Right. Well, and, you 15 know, let's make sure that we invited the people that 16 are on the Skype line as part of this public input, 17 too. So kind of do it in two steps like we would do 18 in a meeting room.
19 Anybody in the virtual meeting room care 20 to make a public comment? Now would be your time.
21 While we're opening up the phone, we'll address the 22 external. So is the external being opened up, 23 external phone line? Can anybody hear me?
24 PARTICIPANT: Yes, the external phone line 25 is open.
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259 1 CHAIR SUNSERI: Okay. So are there any 2 members of the public listening in that would care to 3 make a statement or comment at this point in time, 4 state your name and provide your comment.
5 MS. FIELDS: Yes, yes. My name is Sarah 6 Fields. I'm with an organization called Uranium 7 Watch. And I've been following the DCA process and 8 the ACRS meetings for quite some time.
9 I'm going to go back to the very beginning 10 of the day. And I am flabbergasted and very concerned 11 about the sudden inclusion of a standard design 12 approval approval within the context of the DCA 13 process.
14 I believe that this proposal by NuScale 15 and NRC staff is misleading, dishonest and 16 inappropriate. It does not reflect well on the NRC 17 and the openness of the DCA process.
18 The public was never informed of any sort 19 of inclusion or reference to the DCA in this design 20 certification process.
21 The July 13 NuScale request with standard 22 design approval based on the NuScale standards plan 23 design certification application was not made publicly 24 available until earl this morning, less than hour 25 before the meeting. It was not on the ACRS agenda.
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260 1 The letter states NuScale also requests 2 that the Advisory Committee on Reactor Safeguards 3 consider the same docketed and reviewed information as 4 a basis for issuing a report pursuant to 10 CFR 50.53, 5 which would be the standard design certification and 6 10 CFR 52.141, which are the requirements for the 7 standard design approval. And that's for the NuScale 8 DCA and SDA, respectively.
9 NuScale refers to docketed and reviewed 10 information, but there's no docketed and reviewed 11 application related to the SDA, and there are a number 12 of issues that will be included in the SDA.
13 With the ACRS, there's really no 14 information about, and the public has no information 15 about, for example, NuScale intends to achieve a 25 16 percent power uprate. I have no idea how they're 17 going to carry that out. But I feel that it's very 18 important. I know the ACRS and the NRC think that 19 it's important.
20 I think the ACRS and the NRC staff should 21 actually read the regulation at Part 52, Subpart E, 22 Standard Design Approvals.
23 In Section 52.141, referral to the HERS, 24 which states the condition shall refer a copy of the 25 application to the ACRS. The ACRS shall report on NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.
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261 1 those portions of the application which concern 2 safety.
3 NuScale and the NRC above indicated that 4 the NuScale SDA application will not be submitted 5 until the fourth quarter of 2021. Therefore, the 6 Commission is unable to refer a copy of the 7 application to the ACRS when the ACRS cannot report on 8 any aspect of the SDA application.
9 It's not appropriate for the NRC to ask 10 for any type of ACRS approval before the application 11 is then received and reviewed by the ACRS.
12 The ACRS and NRC would not be compliant 13 with Part 52, Subpart E, if the ACRS issued the DCA 14 report that included any reference to the SDA.
15 I feel these regulations have force and 16 effect, and the NRC and the ACRS should not ignore 17 them. Also Ms. Bradford said that the staff approval 18 of the SDA application only involved the sending of a 19 letter. That's not quite accurate.
20 The regulation states upon the completion 21 of its review of a submittal under this subpart, 22 that's Subpart B, and receipt of a report by the 23 Advisory Committee on Reactor Safeguards under 52.141 24 of the subpart, the NRC staff shall publish a 25 determination in the Federal Register as to whether or NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.
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262 1 not the design is acceptable subject to appropriate 2 terms and conditions and seek an analysis of the 3 design in the form of a report available on the NRC 4 website.
5 And there's also some good information in 6 the regulation about the finality of the standard line 7 approval. In the discussion this morning, the NRC 8 gave the impression that the SDA was kind of fluid, 9 and things could change during an application process.
10 But 52.145 says an approved design must be 11 used and relied upon by the NRC staff and the ACRS in 12 their review of any individual facility license 13 application that incorporates by reference a standard 14 design approved in accordance with this paragraph 15 unless there exists significant new information.
16 This substantially affects the earlier 17 determination for other good cause. In sum, I don't 18 think it's legal for the ACRS to make any reference to 19 some possible future SDA application as part of its 20 final report on the standard design and as part of a 21 rulemaking. Thank you.
22 CHAIR SUNSERI: Okay. Thank you for the 23 comment. Any other public members care to make a 24 comment? So no others?
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263 1 to public comments, but for the sake of transparency, 2 I think it's appropriate to say that the SDA has been 3 brought before the Committee this week --
4 MEMBER KIRCHNER: Matthew, stop for a 5 moment. Someone has to mute their mic. They're 6 interfering with the audio.
7 CHAIR SUNSERI: Okay. I can hear it from 8 my side. It sounded okay to me. Am I coming through 9 okay now, Walt?
10 MEMBER KIRCHNER: Yes. You're okay now.
11 CHAIR SUNSERI: Okay. So let me back up.
12 The SDA that was brought to us at the start of this 13 meeting is an SDA that covers the same scope of 14 design, the certified design application that we've 15 been reviewing for the last two years.
16 There is another SDA coming forward that 17 is the "uprated" NuScale module design. The actions 18 we're being asked to take now have nothing to do with 19 that future SDA. It's only the SDA that covers the 20 certified design scope that we have been reviewing for 21 the last couple of years now. I just wanted to add 22 that clarification. Okay? Any other questions?
23 MEMBER KIRCHNER: Also just not to correct 24 you, Mr. Chairman, but we actually started the ACRS 25 review of the NuScale design, our first letter report NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.
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264 1 was in May of 2016.
2 CHAIR SUNSERI: Okay. So quite a while 3 back. Any other comments? Okay. Let's close the 4 public line. I want to check the meeting room one 5 more time, the virtual meeting room. Any members want 6 to make a public comment? Now is your opportunity.
7 Okay. So we'll close off the public comment period.
8 And Walt we are at this point in time 9 where we are going to transition out of what I'll call 10 the discovery phase of our going through the report 11 preparation phase of these two letters that you 12 mentioned at the start, the blind distribution report 13 and the final letter.
14 MEMBER MARCH-LEUBA: But we want to go 15 around the table.
16 MEMBER KIRCHNER: Yes, Mr. Chairman, if we 17 could, could we go around the table to members for any 18 observations or comments that they want to make. And 19 I want to remind everyone this is part of the 20 transcript and public record.
21 CHAIR SUNSERI: Okay. So go ahead, Walt, 22 facilitate it.
23 MEMBER KIRCHNER: So members?
24 MEMBER MARCH-LEUBA: I want to make some 25 comments. As ACRS members, we have to face the NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.
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265 1 official obedience on the record so.
2 MEMBER KIRCHNER: Jose, let's do the 3 following. Certainly, you and I have pretty much 4 dominated the members' conversation. Let's just go in 5 order and start with Dr. Ballinger.
6 MEMBER BALLINGER: Not at this time. In 7 the closed session.
8 MEMBER KIRCHNER: Dr. Bley?
9 MEMBER BLEY: Nothing additional for me.
10 MEMBER KIRCHNER: Mr. Brown?
11 MEMBER BROWN: Nothing else for me right 12 now. Thank you.
13 MEMBER KIRCHNER: Dr. Dimitrijevic.
14 MEMBER DIMITRIJEVIC: Well, yes, I will 15 have some comments but they cannot be in the open 16 session. But it is going to be collectively our, you 17 know, taking our position how to address this in the 18 final letter. So no additional comments, no.
19 MEMBER KIRCHNER: Okay. Thank you. Let 20 me see. I think we go next to -- I'm going to skip 21 Dr. March-Leuba for the moment and go on to Dr. Petti.
22 MEMBER PETTI: So I just want to say that 23 my perspective on this issue has shifted somewhat 24 based on the real detail that we heard from the staff 25 and some of the discussion of potential operating NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.
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266 1 procedures that were sort of brought up by NuScale.
2 There were some things that I hadn't before that 3 changed my view. And I'm hoping to reflect some of 4 that in the letter. That's it.
5 MEMBER KIRCHNER: Dr. Rempe?
6 MEMBER REMPE: Hi. Can you hear me? I'm 7 a little worried about my internet connection, but is 8 the sound coming up?
9 MEMBER KIRCHNER: We hear you loud and 10 clear.
11 MEMBER REMPE: Okay. I may also have some 12 changes in my thoughts. But I would like to actually 13 see Ben Bristol's comments in writing so I can think 14 about it. Having something come in last minute is 15 difficult to reflect upon with the screening that's 16 needed. Thank you.
17 MEMBER KIRCHNER: Dr. Riccardella.
18 MEMBER RICCARDELLA: Well, you know, I 19 have some comments probably more applicable to the 20 letter writing session. But unfortunately, I'm unable 21 to attend tomorrow. I have a conflict with another 22 engagement so I'm going to say them now.
23 You know, what I'm hearing is that 24 everyone's judgment and intuition is that sufficient 25 mixing will occur and prevent unacceptable reactivity NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.
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267 1 insertion. But everyone also agrees that more work in 2 the form of detailed analyses are necessary to confirm 3 this judgment. And that's what I keep hearing over 4 and over and over again for, like, weeks now.
5 But, you know, it comes down to one key 6 question is the timing. I understand from the 7 thermodynamics folks that counts of these types are 8 going to take three to six months to be performed.
9 And the question on timing, you know, it's basically 10 a bipolar question.
11 Is it necessary to delay the certification 12 of SDA until those calculations are complete? Or is 13 it okay to approve, for us to approve in our letter, 14 that the certification be approved but with the caveat 15 that these calculations need to be completed before 16 the COL application.
17 And I personally come down on the side of 18 the second point. It's a safety concern. In my 19 opinion, there's no safety issue at this time since 20 we're talking about a paper reactor. There's no 21 reactor that's going to be built or operated until the 22 final piece, the final calculations are approved.
23 I think that as long as we point in our 24 letter, document in our letter, the need for these 25 calculations and analyses to support the procedures, NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.
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268 1 that I would vote to go ahead with the certification 2 or SDA. That's all I have.
3 MEMBER KIRCHNER: Thank you, Pete.
4 MEMBER BLEY: Hello? This is Dennis. If 5 I could get another chance I would appreciate it.
6 MEMBER KIRCHNER: Yes, sir. Chairman 7 Sunseri?
8 CHAIR SUNSERI: Walt, I don't have 9 anything else to add at this time.
10 MEMBER KIRCHNER: Okay. I skipped over 11 Member March-Leuba. Do you want to make a further 12 statement at this point, Jose?
13 MEMBER MARCH-LEUBA: Yes, I do. But I 14 will let Dennis comment on his. I will let Dennis go 15 first.
16 MEMBER BLEY: Thank you, Jose. This is 17 very short. I'm getting a little concerned that we're 18 getting good information, useful information today, 19 but we have to write our letter on the design 20 certification based on the application and the SER not 21 on informally -- well, even through a meeting 22 presented, thoughts and ideas that aren't documented 23 in those documents. That was all.
24 MEMBER KIRCHNER: Thank you, Dennis.
25 Jose.
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269 1 MEMBER MARCH-LEUBA: Thank you. I will 2 first like to thank Dennis for (audio interference).
3 That was a thought. But my thoughts, these are my 4 closing remarks on the record are more detailed than 5 this. And I want to take a reality check and take a 6 trip back to memory Lane.
7 Let's go back to December 2019. We have 8 an FSAR. We have a safety evaluation report approved.
9 We are ready for going to lawyers and doing 10 signatures.
11 And everybody, by everybody I mean the 12 applicant, the staff and ACRS knew the downcomer would 13 (audio interference) when the riser uncovers. But the 14 staff and the applicant had to spend many years 15 working on a boron solution to handle all those 16 calculations.
17 And everybody in the universe, but one 18 person, and now I know it was two because there is a 19 different opinion, was of the opinion that that was a 20 problem. Everybody, minus two, thought that was okay.
21 We will develop procedures. We will go ahead.
22 Everything is fine.
23 Through the (audio interference) a guy 24 finally performed the formal calculation and took it 25 seriously. They discovered, because before they were NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.
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270 1 saying there were various -- yet the crucial (audio 2 interference) de-borates, but there is no mechanism to 3 get that water into the core. When they run the 4 calculation, they didn't find one mechanism but two 5 mechanisms by which the water could get into the core.
6 They found two mechanisms by which the 7 water could get into the core. That was the normal 8 evolution of the AL offs. They don't require any 9 failures.
10 Now we're back in July 2020, and I'm being 11 told exactly the same thing. There is no mechanism to 12 get the water into the core and cause damage. They 13 have not calculated it. We have not done a scientific 14 estimation of what the problem is. And there is a lot 15 of talk. A lot of high waving, but figures, looking 16 at all the tests but no calculation.
17 We, I mean, learned our lesson from the 18 December 2019 signature. I just cannot believe that 19 the staff is here to insist that a one dollar per 20 connect pre-activity run have different consequences.
21 I believe that it is off by a factor of five, and it 22 should be six, seven, eight.
23 But I cannot believe that that payment is 24 -- and the staff is here. So that's all I wanted to 25 say. I certainly learned my lesson in December 2019, NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.
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271 1 and I think we're making the same mistake now. Thank 2 you very much, Mr. Chairman.
3 MEMBER KIRCHNER: Thank you, Jose. I just 4 caution again that everybody -- the ACRS will only 5 make a statement through its final letter report on 6 the subject. You speak too liberally in categorizing 7 other members' positions. So don't include me in with 8 everybody else. And we recognize your point.
9 So at this point, Mr. Chairman, I think I 10 turn it back over to you. I've got my eye on the 11 hour1.273148e-4 days <br />0.00306 hours <br />1.818783e-5 weeks <br />4.1855e-6 months <br />. It's coming up on 5:30 Eastern Time.
12 Our next piece of business would be to go 13 off the record to start letter writing. I will leave 14 it to you to decide whether we start fresh first thing 15 in the morning or we continue this afternoon. Thank 16 you.
17 MR. MOORE: Mr. Chairman, this is Scott.
18 For the staff, could you go over the sequence of 19 events? Are we going to go to a closed proprietary 20 session?
21 CHAIR SUNSERI: Yes. If I can finish 22 without being interrupted, I'm going to do that.
23 MR. MOORE: Thank you.
24 CHAIR SUNSERI: So, Walt, I just wanted to 25 confirm that there is no closed meeting. We're NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.
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272 1 finished with all of our presentations?
2 MEMBER KIRCHNER: Yes, you're correct. We 3 do not require a closed meeting.
4 CHAIR SUNSERI: Okay. Very good. So I'm 5 going to recommend that we do not conduct any further 6 business tonight. That you have circulated proposed 7 draft letters around. I think the members' time would 8 be best served thinking about those draft proposals 9 bouncing off what we heard today and getting our 10 thoughts ready for report preparation for tomorrow.
11 So that's what I would like to do is close 12 up today. We will soon go off the transcript. We 13 will pick up at 9:30 tomorrow morning. It will be an 14 open session, but it will be letter writing without a 15 transcriber.
16 And the first course of business then 17 would be to do as we normally do, you will introduce 18 the letter. We'll cover, you know, with conclusions 19 and recommendations, and you will facilitate the 20 review of that letter. Is that the --
21 MEMBER KIRCHNER: Yes. Thank you, sir.
22 That would work well. So we'll start tomorrow at 23 9:30. And I will read the letter first. And then 24 we'll follow our normal procedures of major comments 25 and then proceed.
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273 1 CHAIR SUNSERI: So we will release this 2 transcriber after today. As far as staff engagement, 3 as you pointed out before, let's just be clear on 4 this, this is the members' deliberation. So we will 5 only have need for staff engagement if we encounter a 6 question of fact or if there is a question of fact 7 that we don't understand, and we would ask for some 8 clarification on that. But no further back and forth 9 deliberation with the staff. Is that understood by 10 everyone? Okay.
11 And so now I would ask if anybody has any 12 questions. And then, if so, so we'll pick up with the 13 blind resolution letter tomorrow. We'll work it until 14 it's done, however long it takes. And then we will go 15 to the final letter report after that.
16 And right now I know people have questions 17 for me. Are we going to work through Friday or 18 whatever? I can't say. Right now we're scheduled to 19 work through Saturday morning. And I think we just 20 have to get through more of this week before we can 21 make a judgment on what it looks like as far as 22 finishing up.
23 So now I'll pause and ask does anybody 24 have any questions about the sequence of events for 25 tomorrow or the rest of the week?
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274 1 MR. MOORE: This is Scott. I don't have 2 any questions. Mike Snodderly, do you?
3 MR. SNODDERLY: No. Just I'm going to be 4 online until 7:00 p.m. and then I have to go to 5 another location so I won't be online after that. But 6 I will check things early in the morning. So if 7 people need documents and things try to get that to me 8 in the next hour here, please.
9 MR. MOORE: And, Mike, does Sandra have 10 the document that she'll need for tomorrow morning?
11 MR. SNODDERLY: Yes, we are ready to go.
12 And it has the latest references in it.
13 MR. MOORE: Great. Thank you.
14 CHAIR SUNSERI: Thank you, Mike.
15 MEMBER BROWN: Can I confirm something?
16 This is Charlie. The correct revisions for the boron 17 letter are Rev. 2 and for the NuScale letter is Rev.
18 5 based on stuff that has been placed in the files?
19 CHAIR SUNSERI: That's correct, Charlie.
20 MEMBER BROWN: Okay. Thank you.
21 CHAIR SUNSERI: Okay. Well, then, thank 22 you for everyone's participation today, input. And 23 it's 5:33. We are now adjourned. Thank you.
24 (Whereupon, the above-entitled matter went 25 off the record at 5:33 p.m.)
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Back-up Slides RES Slides for ACRS Meeting 7/21-22/2020
SET / IET Overview
- Hibiki and Ishii
- Boesmans and Berghmans
- LINX
- CCTF
- SCTF
- PKL
Literature Review
- Hibiki and Ishii summarized findings over many experimental campaigns that internal recirculation occurs near pool boiling conditions in large pipe geometries and bundle geometries
- A key process that affects the 3D flow field is channeling of voids into a central column
- At LINX facility, voiding in adiabatic conditions drove internal recirculation
- At CCTF, radial power differences enhanced internal recirculation
- At PKL facility, internal recirculation homogenized the axial and radial boron distribution
Hibiki-Ishii Review Boesmans and Berghmans LINX CCTF CCTF SCTF SCTF Primrkreislauf Primary Circuit Reactor Coolant System (PKL)
Information Follows
PKL PKL SET/IET References
- Hibiki, T. and Ishii, M., One-dimensional Drift Flux model for Two-phase Flow in a Large Diameter Pipe, Intl. Journal of Heat and Mass Transfer 46 (2003) pp.1773-1790.
- Staedke, H., Franchello, G., Worth, B., Graf, U., Romsedt, P., Kumbaro, A., et al.,
Advanced Three-dimensional Two-phase Flow Simulation Tools for Application to Reactor Safety (ASTAR), Nucl. Engr. And Design, 235 (2005) pp. 379-400.
- Bosemans, B and Berghmans, J., Level swell in pool boiling with liquid circulation, Intl. Journal of Heat and Mass Transfer 38 (1995) pp.989-998.
- NUREG/IA-0127, Reactor Safety Issues Resolved by the 2D/3D Program, July 1993 (ADAMS Accession No. ML062560279)
- "Analysis Report on SCTF Core-I and II Reflood Test," prepared by Japan Atomic Energy Research Institute, JAERI-Memo-01-348.
- TRACE V5.0 Assessment Manual Appendix C: Integral Effects Tests
- PKL III G5.1 Test Report PTCTP-G/2011/en/0004 Rev. B, Investigation on Boron Precipitation following a Large Break LOCA, March 2011 (ADAMS Accession No. ML14099A208).
Monitoring Subcritical Margin
- Similar to startup procedures, ex-core nuclear instrumentation can be used to monitor subcritical margin.
- Subcritical multiplication monitoring is used with 1/M plots typically to predict critical rod position.
1/M Plot (from DOE Fundamentals Handbook)
Timing of Downcomer Dilution Approximate Time of ECCS DC Reactor Time to reach Time to reach Steaming Rate Actuation Concentration Power 100 ppm 10 ppm post-ECCS seconds ppm %RTP kg/sec days days 1700 1000 1.0 0.74 0.96 10.3 2800 900 1.0 0.74 0.86 9.3 3300 800 1.0 0.74 0.77 8.3 1700 1000 0.5 0.37 1.89 20.6 2800 900 0.5 0.37 1.70 18.5 3300 800 0.5 0.37 1.49 16.5 1700 1000 0.2 0.15 4.70 51.5 2800 900 0.2 0.15 4.19 46.3 3300 800 0.2 0.15 3.68 41.1
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