ML22049B554
| ML22049B554 | |
| Person / Time | |
|---|---|
| Issue date: | 01/20/2022 |
| From: | Advisory Committee on Reactor Safeguards |
| To: | |
| Abdullahi, Z, ACRS | |
| References | |
| NRC-1812 | |
| Download: ML22049B554 (49) | |
Text
Official Transcript of Proceedings NUCLEAR REGULATORY COMMISSION
Title:
Advisory Committee on Reactor Safeguards Thermal Hydraulics Subcommittee Docket Number: (n/a)
Location: teleconference Date: Thursday, January 20, 2022 Work Order No.: NRC-1812 Pages 1-34 NEAL R. GROSS AND CO., INC.
Court Reporters and Transcribers 1716 14th Street, N.W.
Washington, D.C. 20009 (202) 234-4433
1 1
2 3
4 DISCLAIMER 5
6 7 UNITED STATES NUCLEAR REGULATORY COMMISSIONS 8 ADVISORY COMMITTEE ON REACTOR SAFEGUARDS 9
10 11 The contents of this transcript of the 12 proceeding of the United States Nuclear Regulatory 13 Commission Advisory Committee on Reactor Safeguards, 14 as reported herein, is a record of the discussions 15 recorded at the meeting.
16 17 This transcript has not been reviewed, 18 corrected, and edited, and it may contain 19 inaccuracies.
20 21 22 23 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.
(202) 234-4433 WASHINGTON, D.C. 20005-3701 www.nealrgross.com
1 1 UNITED STATES OF AMERICA 2 NUCLEAR REGULATORY COMMISSION 3 + + + + +
4 ADVISORY COMMITTEE ON REACTOR SAFEGUARDS 5 (ACRS) 6 + + + + +
7 ACCIDENT ANALYSIS: THERMAL HYDRAULICS SUBCOMMITTEE 8 + + + + +
9 OPEN SESSION 10 + + + + +
11 THURSDAY 12 JANUARY 20, 2022 13 + + + + +
14 The Subcommittee met via Video 15 Teleconference, at 9:30 a.m. EST, Jose March-Leuba, 16 Chairman, presiding.
17 COMMITTEE MEMBERS:
18 JOSE MARCH-LEUBA, Chair 19 RONALD G. BALLINGER, Member 20 CHARLES H. BROWN, JR. Member 21 GREG HALNON, Member 22 WALTER KIRCHNER, Member 23 DAVID PETTI, Member 24 JOY L. REMPE, Member 25 MATTHEW SUNSERI, Member NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1716 14th STREET, N.W., SUITE 200 (202) 234-4433 WASHINGTON, D.C. 20009-4309 www.nealrgross.com
2 1 ACRS CONSULTANT:
2 STEPHEN SCHULTZ 3
4 DESIGNATED FEDERAL OFFICIAL:
5 ZENA ABDULLAHI 6
7 ALSO PRESENT:
8 STEFAN ANTON, Holtec International 9 GIANCARLO DELFINI, Holtec International 10 JEAN FLEMING, Holtec International 11 PRITHVISH GOWDA, Holtec International 12 JOSHUA KAIZER, NRR 13 ROBERT LUKES, NRR 14 ABRAR MOHAMMAD, Holtec International 15 ADAM RAU, NRR 16 ANDREA STERDIS, Holtec International 17 KELLY TRICE, Holtec International 18 19 20 STEFAN ANTON 21 GIANCARLO DELFINI 22 JEAN FLEMING 23 PRITHVISH GOWDA 24 EKATERINA LENNING 25 BILL NOVAL NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1716 14th STREET, N.W., SUITE 200 (202) 234-4433 WASHINGTON, D.C. 20009-4309 www.nealrgross.com
3 1 ALYSE PETERSON 2 ADAM RAU 3
4 5
6 7
8 9
10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1716 14th STREET, N.W., SUITE 200 (202) 234-4433 WASHINGTON, D.C. 20009-4309 www.nealrgross.com
4 1 CONTENTS 2 Page 3 I. ACRS Chairman Introductory Remarks 4 March-Leuba . . . . . . . . . . . . . . . . 5 5 II. NRR Staff Open Session Remarks 6 Robert Lukes . . . . . . . . . . . . . . . 6 7 III. Holtec Staff Opening Remarks 8 Kelly Trice . . . . . . . . . . . . . . . . 7 9 IV. Holtec Staff Open Session 10 Andrea Sterdis . . . . . . . . . . . . . . 9 11 Stefan Anton . . . . . . . . . . . . . . . 11 12 V. NRC Staff Open Session 13 Josh Kaizer . . . . . . . . . . . . . . . . 23 14 Adjourned . . . . . . . . . . . . . . . . . . . . 34 15 16 17 18 19 20 21 22 23 24 25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1716 14th STREET, N.W., SUITE 200 (202) 234-4433 WASHINGTON, D.C. 20009-4309 www.nealrgross.com
5 1 P-R-O-C-E-E-D-I-N-G-S 2 9:30 a.m.
3 CHAIR MARCH-LEUBA: Okay, the meeting will 4 now come to order. This is a meeting of the ACRS 5 Accident Analysis Thermal Hydraulics Committee. I am 6 Jose March-Leuba, Chairman of this Committee.
7 Because of COVID-19 concerns this meeting 8 is being conducted remotely. Members in attendance 9 are Ron Ballinger, Charles Brown, Greg Halnon, David 10 Petty, Joe Rempe and Matt Sunseri. We also have a 11 consultant, Steven Schultz, in attendance.
12 So this topic is Holtec Licensing Topical 13 Report HI2200750 Rev 0 entitled, Holtec Spent Fuel 14 Heat up Calculation Methodology.
15 To protect proprietary information, we 16 will be transferring to a closed session later. But 17 we will first hear an overview from both Holtec and 18 the Staff at a higher level now.
19 We have not received any requests for 20 public comments, but we will have an opportunity for 21 public comments at the end of the open portion of the 22 meeting.
23 If you are using the phone line link you 24 will need to use *6 to unmute yourself.
25 The ACRS was established by a statute and NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1716 14th STREET, N.W., SUITE 200 (202) 234-4433 WASHINGTON, D.C. 20009-4309 www.nealrgross.com
6 1 is covered by the Federal Advisory Committee Act, 2 FACA. As such, the Committee can only speak through 3 its published letter reports. Any comments raised by 4 members today are their individual opinions.
5 The ACRS section of the U.S. NRC public 6 website provides our chapter, bylaws, agendas, letter 7 reports, and full transcripts for the open portions of 8 all full and subcommittee meetings. Including the 9 slides presented there.
10 The designated federal official today is 11 Zena Abdullahi.
12 A transcript of the meeting is being kept.
13 Speak clearly and state your name for the benefit of 14 the court reporter. Please keep the microphone on 15 mute when not in use, and don't use video feed to 16 minimize bandwidth problems.
17 At this point, let's request the NRC Staff 18 to start with introductory remarks from Mr. Lukes.
19 Robert.
20 MR. LUKES: Yes. Good morning. My name 21 is Bob Lukes and I'm the branch chief of the nuclear 22 fuel and methods branch in NRR.
23 Because of the complexity of the reviews 24 performed by the fuels branch, we greatly value the 25 ACRS input to our safety evaluations. Today's staff NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1716 14th STREET, N.W., SUITE 200 (202) 234-4433 WASHINGTON, D.C. 20009-4309 www.nealrgross.com
7 1 will be presenting on our review of the Holtec spent 2 fuel pool heat up calculation methodology.
3 This is a unique topical report which had 4 a number of challenging aspects to the review.
5 Specifically, it's a first of a kind topical report 6 and there is limited empirical data requiring staff to 7 rely heavily on engineering judgment.
8 We believe our review is thorough and 9 complete, but look forward to any ACRS insights on our 10 safety evaluation. My staff and I are appreciative of 11 the opportunity to present the result of our review to 12 you today. Thank you.
13 CHAIR MARCH-LEUBA: Thanks, Bob. Now I 14 would like to introduce Kelly Trice from Holtec to 15 produce the introductory remarks.
16 MR. TRICE: Good morning, and thank you 17 for meeting with us. My name is Kelly Trice, I'm the 18 president of Holtec decommissioning international. We 19 appreciate the opportunity to address the ACRS 20 subcommittee regarding the Holtec topical report on 21 the method for determining spent fuel assembly heat up 22 during a theoretical drain down event of a spent fuel 23 pool.
24 This topical report is important to Holtec 25 and our decommissioning process because it measurably NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1716 14th STREET, N.W., SUITE 200 (202) 234-4433 WASHINGTON, D.C. 20009-4309 www.nealrgross.com
8 1 enhances nuclear safety by providing an innovative, 2 yet simple to calculate, methodology for arranging the 3 spent fuel in the pool such that the risk of a 4 zirconium fire reaction is eliminated sooner than 5 traditional methodologies currently be utilized in the 6 industry.
7 We thank you for your time this morning 8 and look forward to a constructed discussion. Ms.
9 Andrea Sterdis and Dr. Stefan Anton will be our 10 presenters for both the open and closed sessions.
11 Thank you.
12 CHAIR MARCH-LEUBA: Thank you, Kelly.
13 Before going into the open session by Holtec, let me 14 remind you that this is open session, and we will have 15 an opportunity to discuss, in detail, the proprietary 16 portions within an hour from now in the other session.
17 So please, do try to keep your questions 18 nonproprietary.
19 Andrea and Jean, who's going to show the 20 slides?
21 MS. STERDIS: Hello, this is Andrea. Jean 22 is going to share the slides.
23 CHAIR MARCH-LEUBA: Well go ahead. We can 24 see them now, I believe.
25 MS. STERDIS: There we go.
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9 1 CHAIR MARCH-LEUBA: Yes, I can see the 2 slides.
3 MS. STERDIS: Okay. Good morning. My 4 name is Andrea Sterdis and I am vice president at 5 Holtec focused in the decommissioning arm of Holtec.
6 I have over 40 years of experience in the 7 industry. And I have spent a lot of time in 8 regulatory. And so I bring that background with me.
9 My last, about my last seven years, have all been 10 focused on decommissioning plants.
11 I want to focus on the agenda. We are 12 going to go through introductions briefly. I'll just 13 do some introductions so that you know that we have 14 some individuals here.
15 Dr. Stefan Anton will follow me. He is 16 the technical lead and he is the expert in this 17 methodology development.
18 We have Daboo Madundar (phonetic), Abrar 19 Mohammad and Prithvish Gowda and Jean Fleming. All of 20 them are from Holtec.
21 Jean is our decommissioning VP of 22 regulatory and environmental affairs. And the others 23 are technical experts in the area of thermal analysis 24 for spent fuel throughout both the storage and the 25 fuel pool, as well as the dry casks.
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10 1 We also have Giancarlo Delfini with us 2 today. Giancarlo is the manager of reactor fuel at 3 Indian Point. He joined our team at the transition of 4 Indian Point from Entergy to Holtec. And he brings a 5 lot of experience in managing, not only spent fuel but 6 also active fuel and SNM for this site.
7 And he has been an integral part of this 8 effort because it's very important as we prepare to 9 apply these, this document and its methodology to 10 decommissioning permanently defueled, permanently shut 11 down units. Indian Point will be our first unit that 12 it is applied to.
13 After the introductions I also want to 14 focus on the fact that I will talk about the purpose 15 of the topical report. And then I will transition to 16 Dr. Anton who will go through the more technical 17 aspects of the methodology.
18 As Jose indicated, this document is 19 proprietary. A lot of the content is proprietary.
20 Not necessarily because of the complexity of the 21 methodology but more because of the innovation and 22 thought that went into the development of this 23 methodology.
24 So we will briefly be going through these 25 items during the open session. And during the closed NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1716 14th STREET, N.W., SUITE 200 (202) 234-4433 WASHINGTON, D.C. 20009-4309 www.nealrgross.com
11 1 session we will dive into more of the details.
2 Next slide please. I already went over 3 this, so we'll go to the next slide.
4 The purpose of this topical report is to 5 provide a methodology that will proactively allow 6 permanently defueled, permanently shut down sites to 7 determine the best overall spent fuel pool arrangement 8 to eliminate the risk of zirc fire as soon as possible 9 after the permanent defueling.
10 This methodology is focused on managing 11 the risk of the zirc fire in a more proactive and 12 stronger enhanced way. And as we go through this 13 methodology today, you will get an opportunity to see 14 how that happens and how it can be used to 15 strategically reduce the risk of zirc fire as soon as 16 possible.
17 With that, I'm going to turn it over to 18 Dr. Anton. And he will go through the technical 19 elements of the methodology. Thank you.
20 MR. ANTON: Yes, good morning, everybody.
21 This is Stefan Anton. Just a couple of more, this is 22 about my background.
23 I'm the vice president of engineering for 24 Holtec International. I'm with Holtec now for 24 25 years, but my technical expertise is in safety NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1716 14th STREET, N.W., SUITE 200 (202) 234-4433 WASHINGTON, D.C. 20009-4309 www.nealrgross.com
12 1 analysis for dry storage systems, and also for, to 2 some degree, for wet storage systems for criticality 3 analysis for wet storage systems.
4 So here at Holtec I'm the lead of the 5 nuclear analysis group which takes care of the 6 criticality and fueling analysis. Before I joined 7 Holtec I worked in Germany in, essentially in the same 8 area.
9 And there I developed the methodology the 10 thermal qualification of the German transport and 11 storage systems, the cask systems. That goes back to 12 the '80s.
13 And my dissertation for my doctorate of 14 engineering also was related to that. It was actually 15 about the qualification of the computer codes that we 16 developed back them through comparison with 17 measurements that have been done in Germany for these 18 systems.
19 But now, I think that should be more than 20 enough. Let me go to what we're doing here. So this 21 is the public part of our presentation. And so, just 22 from a high level I wanted to basically introduce the 23 entire subchapter.
24 The general problem description is, if 25 there is a beyond design basis accident in the form of NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1716 14th STREET, N.W., SUITE 200 (202) 234-4433 WASHINGTON, D.C. 20009-4309 www.nealrgross.com
13 1 a drain down event of a spent fuel pool, of course the 2 cladding of the fuel assemblies in the spent fuel pool 3 that would heat up because you have the loss of the 4 water pooling in the pool.
5 And the cladding temperature, if the 6 cladding temperature exceed a certain value, there is 7 the possibility of an exothermal reaction with the 8 air. That's possibly resulting in what is commonly 9 called a zirconium fire, or a zirc fire. So this is 10 kind of the best word.
11 And of course, this is something that we 12 have to make sure that we avoid. That such a, try as 13 much as possible to avoid. That such a condition can 14 happen, if ever such a situation would appear at the 15 drain down event of a spent fuel pool.
16 Next slide please. Okay, so to go a 17 little bit more into detail. The acceptance criteria, 18 and what is the principle approach that has been done 19 to address this.
20 The acceptance criteria has been developed 21 over time and it has been actually reviewed by then, 22 and approved by the NRC in numerous occasions. And it 23 is basically set to a limit of the cladding 24 temperature within a certain time period.
25 The limit on the cladding temperature that NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1716 14th STREET, N.W., SUITE 200 (202) 234-4433 WASHINGTON, D.C. 20009-4309 www.nealrgross.com
14 1 was selected, as relevant, is 900 degrees Celsius.
2 It's related to the actual thing that would happen, 3 which is not my experience. But that is the generally 4 accepted condition.
5 And then it's expected that is not 6 exceeding within ten hours of any drain down event.
7 And from looking at the discussions of this, the basis 8 for that is the assumption that within ten hours there 9 would be the ability that some mitigating actions 10 would be performed on this. So that's why that, the 11 time was chosen.
12 So then the next steps, so what do you 13 actually do. You need to come up with kind of 14 approach and to develop some acceptance criteria.
15 So since it's a, since the temperature and 16 time involved in there, you need essentially a 17 transient and thermal analysis. And you need to 18 perform a transient thermal analysis of your system, 19 or part of your system.
20 And to basically look, what parameters do 21 you derive from that in the sense of heat loads, decay 22 heat values, of the fuel, and eventually cooling time, 23 that you need to introduce to satisfy that the 24 temperature is actually not exceeded within that limit 25 of time.
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15 1 So, and that led then to the previously 2 used methodology that has been used several times.
3 Submitted to the NRC review and approved by the NRC.
4 And I just want to focus on the main conservatisms of 5 these, of these analysis. What these analysis have 6 been done.
7 They use a single assembly. They analyze 8 a single assembly. They pick the highest decay heat 9 load of all assemblies in a spent fuel pool at a 10 certain site. And then, so that is one, number one 11 and number two.
12 And then the other one, other three, 13 they're basically combined. They say that the 14 assembly is assumed to be completely thermally 15 separated from the environment.
16 It means there is no lateral heat loss to 17 the surrounding assmeblies. Of course, it's in the 18 rack. There are other assemblies around it. Or there 19 may be other assemblies around it, let's put it that 20 way.
21 There would be, there would usually be air 22 flows through the rack of the assembly. That is 23 actually also ignored. And I'll comment on that a 24 little bit later.
25 And any other axial heat loss that could NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1716 14th STREET, N.W., SUITE 200 (202) 234-4433 WASHINGTON, D.C. 20009-4309 www.nealrgross.com
16 1 go through the top and the bottom of the spent fuel 2 into the building, into the floor, or wherever, is 3 actually ignored. So that's the, these are basically 4 the five basic assumptions that have been used in the 5 previously used analysis.
6 It's conservative. The other advantages, 7 also that its implementation is done fairly simple.
8 You can almost do a simple analytical approach. Or 9 for example, just a spreadsheet to come up, in the 10 end, come up with the acceptance criteria with a heat 11 load limit that needs to be met for a certain site, 12 for a certain assembly, so that the 900 degrees within 13 ten hours are met.
14 Let me just briefly go back to the 15 assumption number four, because it's kind of 16 interesting from my perspective because it's not quite 17 immediately clear why you would make this. Because 18 you would have, under normal conditions, you would 19 think that if the pool is ran down you have actually 20 air flow through the assemblies. And specifically, if 21 they heat up to 900 degrees it would be substantial.
22 So this basically, if you're assuming that 23 either the air cannot get out of the rack or it cannot 24 get into the rack. So it's typically, it's either 25 assumed that the top of your rack is closed by NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1716 14th STREET, N.W., SUITE 200 (202) 234-4433 WASHINGTON, D.C. 20009-4309 www.nealrgross.com
17 1 something.
2 Again, it's a beyond design basis. You 3 don't have to actually think about what it could be, 4 but it's closed so that the air cannot get out.
5 The other case would be that no air can 6 get in. Now usually they are always, the racks are of 7 course open at the bottom so that the water would go 8 in there. So it's kind of assumed, it's called a 9 smart flood.
10 It's not unusual in other areas that you 11 basically say, well, the water level goes down far 12 enough so that it doesn't cool the assembly, but it 13 doesn't go down so far that the bottom openings are 14 free again and let air in. I just wanted to mention 15 that and that this is one of the major assumptions 16 here. All very conservative.
17 Implementation, again, I said that it's 18 fairly simple and it can be done with a simple 19 analytical calculation or approach.
20 So let me then, that is --
21 CHAIR MARCH-LEUBA: Steve, this is Jose.
22 MR. ANTON: Yes.
23 CHAIR MARCH-LEUBA: Can you go back to the 24 previous slide?
25 MR. ANTON: Yes.
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18 1 CHAIR MARCH-LEUBA: You made a big deal 2 about how conservative both assumptions four and five 3 are. But since we're in open session, and this is 4 going to be discussed in the closed session, I believe 5 it's nonproprietary. It's marked nonproprietary.
6 You plan to keep those two conservative 7 assumptions in your new methodology, is that correct?
8 MR. ANTON: That is correct.
9 CHAIR MARCH-LEUBA: Excellent.
10 MR. ANTON: Yes. And that's actually, 11 yes, that is correct. And we think, even in the open 12 session, it is important to stress the fact that our, 13 the methodology that we have developed, it doesn't 14 just take out all the conservatisms, that would 15 definitely not be appropriate.
16 CHAIR MARCH-LEUBA: Excellent. Yes.
17 MR. ANTON: Yes. Yes. Okay.
18 CHAIR MARCH-LEUBA: A casual listen may 19 have implied that you wanted to get rid of those 20 conservatisms but you are not.
21 MR. ANTON: Okay, thanks.
22 CHAIRMAN KIRCHNER: Thank you.
23 MR. ANTON: Thanks for asking the 24 question, that we can make clear that we are not doing 25 this. Yes.
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19 1 MEMBER REMPE: Jose, since you've 2 interrupted the speaker I've got a couple of questions 3 on a couple of different slides.
4 First of all, I believe that you mentioned 5 that it isn't your area of expertise, so you can 6 deflect this to the staff. But this 900 degrees C, I 7 think it would behoove us to discuss the conservatism, 8 or not conservatism, in that temperature because when 9 you're worried about exothermic reactions occurring, 10 is there some uncertainty in that temperature and is 11 that conservative or not?
12 Secondly, what about burn-up credit? I 13 know that the staff gives burn-up credit with respect 14 to other aspects of the spent fuel pool and is that 15 totally ignored?
16 Does this method consider high assay low 17 enriched uranium impact on, or higher enriched fuel, 18 and how that will be incorporated into this method?
19 And then last, this point about ignoring 20 air flow in. If you're worried about oxidation, is 21 that always conservative?
22 MR. ANTON: Okay, I think about the 900, 23 let me try to respond to that as far as I can. As I 24 said, I'm not the expert on the reaction on what 25 constitutes the 900 degrees Celsius. I've read about NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1716 14th STREET, N.W., SUITE 200 (202) 234-4433 WASHINGTON, D.C. 20009-4309 www.nealrgross.com
20 1 it, but I will have to defer that to somebody else to 2 talk about. It is something that is published in 3 numerous documents, but as I said, I'm not the expert 4 on that.
5 Secondly, you're asking about burn-up 6 credit. This is completely independent of burn-up 7 credit. Whether you credit burn-up for fuel assembly 8 or not, it's immaterial here because this simply just, 9 the acceptance criteria is, in the end, the heat load 10 of the fuel assemblies.
11 And that is, whether you credit burn-up or 12 not, burnt fuel has a certainly heat load and there 13 are standard methodologies to calculate that. And 14 that is used here. So, that is separated from that.
15 Also, what kind of fuel you have in the 16 end, it's, again, it all comes down what the heat load 17 of the fuel assembly is. Different types of fuel 18 assemblies might have to be treated differently to 19 come up with the heat load.
20 But in the end, the real input and 21 critical parameter here is the heat load of the fuel 22 assembly. Independent on what the other fuel assembly 23 is constructed or designed.
24 And last, in the, with the air flow, I 25 think we can, we need to calculate, we need to discuss NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1716 14th STREET, N.W., SUITE 200 (202) 234-4433 WASHINGTON, D.C. 20009-4309 www.nealrgross.com
21 1 that in the proprietary section. I will then comment, 2 I can then comment on that a little bit more.
3 MEMBER REMPE: Okay, that sounds good.
4 But if I look at the prior slide, it seems to me if 5 you take the highest decay heat of all the assemblies 6 in the spent fuel pool, if you had some credit, would 7 the staff in the existing methodology not say, okay, 8 the highest heat load would be decreased for that 9 spent, for that assembly, because of burn-up credit?
10 And you're saying the staff does not give 11 credit for that, on that item two?
12 MR. ANTON: That is, yes, that is correct.
13 Whether you take burn-up credit for a fuel assembly or 14 not, that is only a question that is interesting in 15 criticality space.
16 If you look at the, if you look at the 17 thermal, at the heat load at the decay heat, that that 18 fuel assembly generates, let me put it that way, you 19 cannot take burn-up credit because you're burn-up 20 creates the heat so you have to always actually 21 consider that the fuel assembly is burnt the way it 22 is.
23 So there is, it's the other way around.
24 What you need, what you can take credit for in 25 criticality you have to assume that here. Otherwise NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1716 14th STREET, N.W., SUITE 200 (202) 234-4433 WASHINGTON, D.C. 20009-4309 www.nealrgross.com
22 1 you would be non-conservative.
2 MEMBER REMPE: All right. Okay, thank 3 you.
4 MR. ANTON: Okay. You're welcome. Okay, 5 so this is basically just a summary. And we are, we 6 have submitted a topical report that improves on the 7 methods.
8 And still, as was highlighted before, the 9 method still implores significant conservatisms.
10 Specifically, it's still assumed there is no air flow 11 flows through the racks and after the drain down 12 event. And as I said, we can comment on the air in 13 the proprietary section.
14 And that brings me to the end of my 15 presentation here for the open session.
16 CHAIR MARCH-LEUBA: Thank you, Steve. So 17 we'll go ahead and move to the Staff open 18 presentation. Josh.
19 And while we put the slides on, Josh 20 Kaizer will be the presenter. While we do this, I 21 wanted to tell the Members that you remember in 2019 22 we reviewed a framework for structure analysis of 23 these requirements that Josh presented to us, and it 24 was part of NUREG-KM-0013.
25 And we reviewed it. And we recommended NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1716 14th STREET, N.W., SUITE 200 (202) 234-4433 WASHINGTON, D.C. 20009-4309 www.nealrgross.com
23 1 that it should be used for other applications, and 2 this is one of those applications. So even though the 3 current is 99.9 percent for the Staff, the ACRS has a 4 0.1 percent grade on recommended that they use it, and 5 I want to take credit for that part.
6 So, Josh, go ahead and do --
7 MR. KAIZER: Will do. Hi, my name is 8 Joshua Kaizer. I wanted to at least share a video 9 because I don't know if you guys have seen us, and 10 Adam Rau is one of our relatively new hires who 11 greatly helped me out with this.
12 As my boss said, I am grateful for the 13 ACRS for this. And I know that, yes, it's required by 14 statute that you guys get to look at anything you 15 want, which I think is a really good thing.
16 But for topical reports that rely heavily 17 on staff engineering judgement, I do think that having 18 the ACRS makes the review go faster. Because if I had 19 to sit back and say, well, wait a minute, I have to 20 make the decision myself, there is a lot of hesitation 21 for an engineer to rely on their own engineering 22 judgement and say, yes, it's done.
23 But to come up with a, I'd say good 24 justification, say this looks good to me, that seems 25 to be helpful. So with that, I just wanted to say hi.
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24 1 I'll kill my video now and continue with the slides.
2 CHAIR MARCH-LEUBA: Hey, Josh, for the 3 members who may not have been assigned --
4 MR. KAIZER: Yes.
5 CHAIR MARCH-LEUBA: -- this in detail, you 6 pointed to the fact that there is very little 7 experimental data to benchmark to date.
8 MR. KAIZER: Yes. And we have multiple, 9 the slides on that. Get to it especially more in the 10 closed session.
11 But I do, the NRC in general is very heavy 12 on stressing engineering judgement. And to me, one of 13 the best checks of engineering judgement when it's 14 used to make decisions is having an independent body 15 look at it and say yes, this judgement makes sense.
16 So, I did want to stress that. Especially 17 in this open session because I think this, coming here 18 was a very big help for this review.
19 All right. Next slide please. All right, 20 so this is Holtec's drain down methodology. They've 21 kind of already described the scenario.
22 And I know Dr. Rempe was talking about the 23 acceptance criterion. And the acceptance criterion 24 here is this 900 degrees for at least ten hours.
25 Which means the fuel temperature has to remain below NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1716 14th STREET, N.W., SUITE 200 (202) 234-4433 WASHINGTON, D.C. 20009-4309 www.nealrgross.com
25 1 900 degrees for the first ten hours, following the 2 complete drain down of the spent fuel pool.
3 That acceptance criterion comes from this 4 NUREG. It's a fairly old NUREG. When I was looking 5 at it, I know Ed Fraum (phonetic) was one of the 6 authors, along with a number of other people, so I 7 think it was written kind of in the late '90s. It 8 definitely predates me at the NRC.
9 And the reason they have 900 degrees there 10 in a bit of a fuzzy font is because, when they were 11 developing the acceptance criterion they weren't 12 really sure which temperature to use. If you have, 13 they were certainly looking at the zirconium oxide 14 reaction. They were looking at it when it starts to 15 run away.
16 And they had a whole bunch of test data 17 they were looking at. And it really depending on if 18 you were in all steam or no steam.
19 If you're in a steam environment, then 20 this 900 degree temperature, is actually goes up to 21 1200 degrees. Because, and I'm honestly not entirely 22 sure why, I was reading the NUREG to understand it but 23 I didn't necessarily understand the physics behind it.
24 But in a steam environment it delays the 25 zirconium oxide reaction. But if you have no steam NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1716 14th STREET, N.W., SUITE 200 (202) 234-4433 WASHINGTON, D.C. 20009-4309 www.nealrgross.com
26 1 and it's just air, then the temperature is closer to 2 900.
3 And even when you read the NUREG and you 4 get the idea of where this acceptance criterion comes 5 from, it was still a little bit fuzzy. So at the end 6 of the day I'm not sure that NUREG even made a 7 recommendation, one, which number to use.
8 But from, as I piece things together, 9 mostly from looking at other spent fuel drain down 10 events, everyone generally uses the 900 degrees number 11 since that's the lower and more conservative number.
12 Holtec --
13 MEMBER REMPE: Thank you, Josh. That's 14 the kind of discussion I wanted to have in the open 15 session --
16 MR. KAIZER: Okay.
17 MEMBER REMPE: -- so I appreciate you 18 going through it.
19 MR. KAIZER: Sure. Holtec's methodology 20 was to demonstrate that their spent fuel pool 21 configuration, and they can perform a simulation which 22 satisfies this acceptance criterion, and that's what 23 we were reviewing.
24 Go ahead, go to the next slide, Kate.
25 What the review goal is, basically we were looking at NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1716 14th STREET, N.W., SUITE 200 (202) 234-4433 WASHINGTON, D.C. 20009-4309 www.nealrgross.com
27 1 is their "reasonable assurance" that Holtec's method 2 can be used to demonstrate that this acceptance 3 criterion has been satisfied. Can we trust what 4 they're doing.
5 I kind of consider this a credibility 6 assessment. I really like, ASME has verification 7 validation and uncertainty quantification standards 8 committee.
9 One of their subcommittees, and this one 10 is on like small medical devices, they have a very 11 good definition of credibility, which is pretty much, 12 can I trust the simulation to be used for what it's 13 going to be used for. So that's what we're looking at 14 here. This is simulation credibility.
15 I referenced that standard just because 16 they're one of the few places that has actually 17 defined simulation credibility. And it is a really 18 good general VVUQ standard. Even though it says small 19 medical devices.
20 I've even argued to them and to other 21 authors, if you read what we wrote in CSAU and in MDAP 22 and what they have there, it all looks very similar.
23 So, we were looking at simulation credibility here, 24 can we trust Holtec simulation.
25 Next slide. And this is kind of the last NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1716 14th STREET, N.W., SUITE 200 (202) 234-4433 WASHINGTON, D.C. 20009-4309 www.nealrgross.com
28 1 slide we have for the open session. I just kind of 2 wanted to lay out how we wrote up our safety 3 evaluation.
4 We were following on the right, that's SRP 5 15.0.2, which is the review of transient accident 6 analysis. And we followed it approximately. And I 7 say approximately in that we just pretty much 8 rearranged the order and group some things.
9 This is a very good, to me it's a very 10 good SRP, for all of the things you need to consider 11 when you're reviewing computational model. I think 12 the order is a little bit out of place so we say, hey, 13 first let's talk about the scenario, talk about the 14 documentation and then look at the evaluation model, 15 which is that complete computational model where we do 16 try to address verification, where we do try to 17 address validation as much as we can.
18 As Jose has already said, there isn't 19 validation data here so what do we do, can we still 20 trust the model. The answer is yes.
21 I personally believe that we end up 22 trusting a lot of models without validation data, it's 23 just you have to have a high degree of trust in those 24 models. And there has to be very good reasons why.
25 And there are. And that's what we'll end up going to NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1716 14th STREET, N.W., SUITE 200 (202) 234-4433 WASHINGTON, D.C. 20009-4309 www.nealrgross.com
29 1 in the detailed portion of the closed portion.
2 Also, we tried to address the uncertainty 3 quantification again. Not much here.
4 And then finally, the quality assurance 5 plan. Which I think is one of the most important 6 parts of performing simulations, but it generally gets 7 overlooked. So that's our conclusion.
8 So this is the, kind of the summary of 9 what our safety evaluation looks like and what we're 10 going to be talking about in more detail in the closed 11 portion. And go ahead, Steven.
12 DR. SCHULTZ: Thank you, Joshua. This is 13 Steven Schultz.
14 I was wondering, not wondering, I would 15 like you to describe, in some detail in the open 16 session here, the work that the staff did in their 17 evaluation model assessment. There was a lot of work 18 that the staff did to do an analytical comparisons, 19 evaluations and analyses associated with the 20 assessment of the work that has been offered by the 21 applicant.
22 MR. KAIZER: Sure.
23 DR. SCHULTZ: And I think it would be 24 useful here for you to describe that in some detail.
25 MR. KAIZER: Sure. And if I don't hit the NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1716 14th STREET, N.W., SUITE 200 (202) 234-4433 WASHINGTON, D.C. 20009-4309 www.nealrgross.com
30 1 exact area, please feel free to jump in and just 2 correct me.
3 This topical, this review, the staff, 4 we've done more confirmatory analysis than I think 5 I've actually done for quite a while in any type of 6 topical report. And we did two major types of 7 confirmatory analysis.
8 One was, we looked at Holtec's method 9 itself. We had some questions. We'll talk about this 10 in the closed section, but their documentation was 11 sufficient such that we could recreate their method, 12 which to me is how you know documentation is good, if 13 someone else can recreate what you've done and get the 14 same numbers. You've got to have pretty good 15 documentation.
16 So we were able to recreate it. We were 17 able to do our own sensitivities because we had some 18 questions and we could address those.
19 But there are some other issues that the 20 Staff was concerned about. Some of the assumptions, 21 and kind of the physical assumptions Holtec made in 22 their methods.
23 So, we talked with research and Dr. Ghani 24 Zigh and we said, hey, Ghani, can you help us come up 25 with a, we use ANSI and so we call it a CFP model, but NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1716 14th STREET, N.W., SUITE 200 (202) 234-4433 WASHINGTON, D.C. 20009-4309 www.nealrgross.com
31 1 there was no fluids in there. It was mostly limited 2 to radiated heat transfer, so you're using ANSI to get 3 the review factors.
4 And we were able to perform a detailed 5 radiated heat transfer model and perform more 6 sensitivities there to confirm some of the staff's 7 concerns. And also some of the staff's findings to 8 say, hey, this is different but we can actually 9 quantify the effect of these things.
10 So, this was, it was very, from my 11 perspective, it was fun. It's interesting being able 12 to just reach out to someone like Ghandi and say, hey, 13 can you help us. And he was extremely responsive.
14 And he had stuff done very, very quickly.
15 And then being able to say, okay, let's do this 16 sensitivity and this sensitivity. So was that the 17 kind of thing that you wanted me to address or is 18 there something else?
19 DR. SCHULTZ: No, that's exactly it. And 20 the other comment I would make, you've talked about it 21 in general, but you did create a, staff did create a 22 very logical evaluation approach. It's not 23 substantially different than what would normally be 24 used, but it was a very detailed and careful approach 25 to perform the overall safety evaluation.
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32 1 MR. KAIZER: I appreciate that. I would 2 love to --
3 DR. SCHULTZ: You summarize it --
4 MR. KAIZER: -- take credit for it --
5 DR. SCHULTZ: You summarize it here, but 6 it is in more detail in the overall safety evaluation.
7 MR. KAIZER: I appreciate that. Honestly, 8 I would, actually, one of the things I've been trying 9 to figure out is how wrote SRP 15.0.2 because I can't 10 figure that out.
11 I think the main author was Norm Lauben.
12 But if anyone is actually interested in how the staff 13 created that approach.
14 We went through SRP 15.0.2 and every place 15 that said the reviewer shall or the reviewer should do 16 something, we highlighted it, and then those things 17 became the criteria that we then wrote up in our SC.
18 It's like, okay, 15.0.2 says do this, here's how we 19 did it.
20 DR. SCHULTZ: I wouldn't be surprised if 21 Norm wasn't involved.
22 MR. KAIZER: Yes.
23 DR. SCHULTZ: All right, thank you.
24 MR. KAIZER: Sure. So that is, you can go 25 to the next slide, Kate. That was the ending I had NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1716 14th STREET, N.W., SUITE 200 (202) 234-4433 WASHINGTON, D.C. 20009-4309 www.nealrgross.com
33 1 for the open portion, unless there are any other 2 questions. Okay. With that I will turn it over to 3 you, Jose.
4 CHAIR MARCH-LEUBA: I'm back. Okay, so we 5 have reached the end of the open session, and we will 6 not return to this phone line this morning.
7 So I would like to ask for the Members, if 8 they want to make another comments or questions for 9 both the Staff or Holtec? Hearing none.
10 Any members of the public are welcome to 11 provide any comments that will be part of the record.
12 And if you are using the phone line, you will just 13 press *6.
14 I'd like to get, from Ron Ballinger, one 15 of his quote about the five seconds and do not say.
16 I can never do it right, but the five second rule has 17 expired and there are no comments, so this concludes 18 the open session portion. We're going off the record.
19 And for the people that have a need to 20 know, we have a closed session Teams meeting that 21 everybody should have access to. And we are scheduled 22 to start at 10:30.
23 But we are a little early, so why don't we 24 start 10:25. It will take a while to get everybody in 25 from the lobby.
NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1716 14th STREET, N.W., SUITE 200 (202) 234-4433 WASHINGTON, D.C. 20009-4309 www.nealrgross.com
34 1 So, let's all meet together at 10:25.
2 I'll try to log in five or ten minutes early so we get 3 you in. Thank you. We are off the record.
4 (Whereupon, the above-entitled matter went 5 off the record at 10:07 a.m.)
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10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1716 14th STREET, N.W., SUITE 200 (202) 234-4433 WASHINGTON, D.C. 20009-4309 www.nealrgross.com
www.holtec.com Topical Report: Method for Determining Spent Fuel Assembly Heat Up During a Theoretical Drain Down Event of a Spent Fuel Pool Holtec Presentation to ACRS Subcommittee OPEN Session January 20, 2022
Agenda
Introductions
Purpose of the Topical Report Problem Description Acceptance Criteria and Principal Solution Previously used Methodology Methodology proposed in Topical Report Calculational Details Summary www.holtec.com l Page 2
Introduction Holtec Kelly Trice - President, Holtec Decommissioning International, LLC (HDI) 1 1 1 1 Jean Fleming - Vice President, HDI Regulatory and Environmental Affairs Andrea Sterdis - Vice President, HDI Decommissioning Stefan Anton - Vice President of Engineering - Technical Expert Group, NPD www.holtec.com l Page 3
Purpose of the Topical Report Provide a methodology to proactively determine the best overall spent fuel pool arrangement to eliminate the risk of a zirc fire as soon as possible after permanent defueling.
The methodology developed by Holtec can be used to gain a significant and real safety benefit that can be recognized.
www.holtec.com l Page 4
Problem Description During a theoretical beyond design basis drain down event of a spent fuel pool, the cladding of the fuel assemblies would heat up due to the loss of water cooling in the pool.
If the cladding temperature exceeds a certain value, there is the possibility of an exothermal reaction with the air, possibly resulting in what is commonly called a zirconium fire or zirc fire.
www.holtec.com l Page 5
Acceptance Criteria and Principal Approach The criteria to evaluate if such a condition may occur, used in previous applications and reviewed and approved by NRC, is that a cladding temperature of 900 °C is not exceeded within 10 hours1.157407e-4 days <br />0.00278 hours <br />1.653439e-5 weeks <br />3.805e-6 months <br /> from the drain-down event.
The principal approach to determine if the condition could occur or not is to perform a transient thermal analysis, and determine the parameters (e.g. cooling time of the fuel assemblies) that needs to be satisfied for the temperature to not exceed the limit within that time.
www.holtec.com l Page 6
Previously used Methodology The methodology previously used, and reviewed and approved by NRC, is a transient thermal calculation using the following main conservative assumptions
- 1. A single assembly is analyzed
- 2. Highest decay heat of all assemblies in the spent fuel pool is applied to that assembly
- 3. No lateral heat loss to surrounding assemblies
- 4. No air flow through the rack and assembly
- 5. No other axial heat loss through the top and bottom of the spent fuel rack Implementation is fairly simple Can be done with a simple analytical calculational approach, or a simple spreadsheet.
www.holtec.com l Page 7
Summary A topical report has been submitted that improves on the method to determine if a zirc fire is possible in a spent fuel pool after the assumed drain-down of the water in the pool.
The method still employs significant conservatisms. Specifically, it still assumes there is no air flow through the rack cell and assemblies after the drain down event.
www.holtec.com l Page 8
Open Session U. S. Nuclear Regulatory Commission Review of Holtec International Topical Report HI-2200750, Revision 0, Holtec Spent Fuel Pool Heat Up Calculation Methodology Holtecs Method for Determining Fuel Assembly Heat Up During a Theoretical Drain Down Event Joshua Kaizer, PhD Adam Rau, PhD Division of Safety Systems Office of Nuclear Reactor Regulation January 20, 2022
Drain Down Methodology Goal Acceptance Criterion Ensuring that the spent fuel temperature remains below 900 °C for at least 10 hours1.157407e-4 days <br />0.00278 hours <br />1.653439e-5 weeks <br />3.805e-6 months <br /> following a complete drain down of the spent fuel pool.
Methodology Goal Demonstrate that the configuration of the fuel in the spent fuel pool satisfies the acceptance criterion.
2
Review Goal Review Goal Is there a reasonable assurance that the Holtecs methodology can be used to demonstrate that the acceptance criterion has been satisfied?
3
Safety Evaluation Outline SRP 15.0.2
- 1. Scenario Identification Process
- 2. Documentation
- 3. Evaluation Model Assessment 3.1 Model Applicability 3.2 Model Verification 3.3 Model Validation 3.4 Data Applicability 3.5 Uncertainty Quantification 3.6 Quality Assurance
- 4. Conclusion 4
Questions 5