ML20023B305
| ML20023B305 | |
| Person / Time | |
|---|---|
| Issue date: | 12/03/2019 |
| From: | Weidong Wang Advisory Committee on Reactor Safeguards |
| To: | |
| Wang, W, ACRS | |
| References | |
| NRC-0732 | |
| Download: ML20023B305 (54) | |
Text
Official Transcript of Proceedings NUCLEAR REGULATORY COMMISSION
Title:
Advisory Committee on Reactor Safeguards Subcommittee on Global Nuclear Fuel Licensing Topical Report Subcommittee Open Session Docket Number: (n/a)
Location: Rockville, Maryland Date: Tuesday, December 3, 2019 Work Order No.: NRC-0732 Pages 1-29 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.
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1 1 UNITED STATES OF AMERICA 2 NUCLEAR REGULATORY COMMISSION 3 + + + + +
4 ADVISORY COMMITTEE ON REACTOR SAFEGUARDS 5 (ACRS) 6 + + + + +
7 SUBCOMMITTEE ON GLOBAL NUCLEAR FUEL (GNF) LICENSING 8 TOPICAL REPORT (LTR), NEDE-33885P REVISION 0, 9 "CONTROL ROD DROP ACCIDENT (CRDA) APPLICATION 10 METHODOLOGY" - OPEN SESSION 11 + + + + +
12 TUESDAY 13 DECEMBER 3, 2019 14 + + + + +
15 ROCKVILLE, MARYLAND 16 + + + + +
17 The Subcommittee met at the Nuclear 18 Regulatory Commission, Two White Flint North, Room 19 T2D30, 11545 Rockville Pike, at 8:30 a.m., Jose 20 March-Leuba, Chair, presiding.
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2 1 COMMITTEE MEMBERS:
2 JOSE MARCH-LEUBA, Chair 3 RONALD G. BALLINGER, Member 4 JOY L. REMPE, Member 5
6 DESIGNATED FEDERAL OFFICIAL:
7 WEIDONG WANG 8
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3 1 C-O-N-T-E-N-T-S 2
3 ACRS Chairman Introductory Remarks . . . . . . . 4 4 NRC Staff Introductory Remarks . . . . . . . . . 6 5 GNF Staff Introductory Remarks . . . . . . . . . 9 6 CRDA Application Methodology, GNF 7 Background, Submittal Overview . . . . . . 10 8 CRDA Application Methodology . . . . . . . . . . 14 9 Adjourn . . . . . . . . . . . . . . . . . . . . . 29 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.
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4 1 P-R-O-C-E-E-D-I-N-G-S 2 8:51 a.m.
3 CHAIR MARCH-LEUBA: This is a meeting of 4 the Thermal-Hydraulics Phenomena Subcommittee of the 5 Advisory Committee on Reactor Safeguards. I am Jose 6 March-Leuba, Chairman of today's Subcommittee meeting.
7 ACRS members in attendance are Joy Rempe 8 and Ron Ballinger. Weidong Wang of the ACRs staff is 9 the federal official for this meeting.
10 During this meeting the Subcommittee will 11 review a draft safety evaluation report for Global 12 Nuclear Fuel Americas, also know as GNFA, Licensing 13 Topical Report NEDE-33885P Revision O, and GNF-CRDA 14 Application Methodology. The Subcommittee will hear 15 presentations by and hold discussions with NRC staff, 16 GNF-A representatives, and other interested persons 17 regarding this matter.
18 The rules for participation in all ACRS 19 meetings, including today, were announced in the 20 Federal Register on June 13, 2019. The ACRS section 21 of the U.S. NRC public website provides our charter, 22 by-laws, agendas, reports, and full transcripts of all 23 full Subcommittee meetings including the slides 24 presented there. A meeting notice and agenda for this 25 meeting will be posted there.
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5 1 We have received no written statements or 2 requests to make an oral statement from the public.
3 The first part of today's meeting is 4 opened to public attendance. The second part of the 5 meeting will be closed in order to discuss information 6 that is proprietary to the licensee and its 7 contractors pursuant to 5 USC 552(b)(c)(4).
8 Attendance at this portion of the meeting 9 that deals with such information will be limited to 10 the NRC staff and those individuals and organizations 11 who have entered into an appropriate confidentiality 12 agreement with them.
13 Consequently, we need to confirm that we 14 have only eligible participants in the room for the 15 closed portions when we get there.
16 The Subcommittee will gather information, 17 analyze relevant issues and facts, and formulate 18 proposed positions and actions, as appropriate, for 19 deliberation by the Full Committee.
20 The rules for participation in today's 21 meeting have been announced as part of the notice of 22 this meeting previously published in the Federal 23 Register. A transcript of the meeting is being kept 24 and will be made available as stated in the Federal 25 Register notice. Therefore, we are requesting the NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.
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6 1 participants in the meeting use the microphones 2 located throughout the room when addressing the 3 Subcommittee.
4 The participants should first identify 5 themselves and speak with sufficient clarity and 6 volume so they may be readily heard. Just a reminder, 7 if your name is in front of you, you don't need to say 8 your name every time you talk. If your name is not in 9 front of you, you tell your name so the court reporter 10 knows who you are.
11 We will now proceed with the meeting.
12 Another reminder. Please place your phones on mute 13 because somebody always forgets and it's annoying when 14 it sounds.
15 Now I'll call on the NRC staff to provide 16 some introductory remarks.
17 MS. ROSS-LEE: Good morning and thank you 18 for your patience with shifting rooms and trying to 19 get all the technology aligned appropriately. My name 20 is MJ Ross-Lee. I'm the Deputy Division Director for 21 the Division of Safety Systems. I want to thank you 22 for coming this morning and for your patience as we've 23 shifted rooms.
24 GNF submitted this topical report in 2008 25 with the intent of implementing the proposed NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.
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7 1 methodology into GESTAR II in 2020 as an option for 2 licensees to analyze the control rod drop accident 3 event. GNF's legacy CDRA analysis methodology is 4 based on generic analysis performed to show compliance 5 with old NRC regulatory guidance.
6 The proposed methodology is an updated 7 approach to explicitly verify that the more recent NRC 8 acceptance criteria are met as well as provide 9 flexibility to licensees for analysis on a case-by-10 case basis. New regulatory guidance on reactivity-11 initiated events, accidents in the form of a Draft 12 Guide 1327, will be reviewed by ACRS within the next 13 few months prior to being finalized.
14 In the interim, the proposed GNF 15 methodology was reviewed with the criteria from the 16 current guidance in Appendix B to the SRP Section 4.2, 17 as well as the Draft Guide. As a result, the staff 18 expects that licensees will be able to utilize the 19 methodology with the most recent regulatory guidance, 20 whether it be the current SRP guidance or the Draft 21 Guide.
22 The interaction between GNF and NRC staff 23 was very productive in effectively identifying and 24 addressing several potential issues with the finding 25 of applicability of the methodology implementation for NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.
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8 1 specific licensees and to clarify potential uses of 2 the methodology not explicitly identified in the 3 topical report.
4 MEMBER REMPE: So I have a question. If 5 I look at your SE, there's a statement in there, and 6 I'm pretty sure it's not proprietary so I can quote 7 it, saying that the time this SE was written, "The 8 Draft Guide is not expected to be finalized." Are you 9 planning to fix that statement?
10 MR. KREPEL: This is Scott Krepel. The 11 Draft Guide was recently finalized. We finished the 12 public comments just a couple of months ago and it's 13 going to go to the ACRS sometime in the next couple 14 months. The safety evaluation is expected to be 15 completed before the Draft Guide becomes finalized as 16 regulatory guidance so the statement will stay as is.
17 MEMBER REMPE: It's a word thing, but if 18 I read this verbatim, at the time this SE was written, 19 Draft Guide 1327 is not expected to be finalized as a 20 regulatory guide. That sounds like ain't never going 21 to happen to me. Probably it should be revised a bit.
22 MR. KREPEL: Sure, I can go ahead and 23 revise that.
24 MEMBER REMPE: Thank you.
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9 1 as you read it, the wording. It will still be draft 2 but it will be finalized at some point in time.
3 MEMBER REMPE: Sounds like it's never 4 going to happen. Thank you.
5 MS. ROSS-LEE: I understand the question 6 now.
7 CHAIR MARCH-LEUBA: With this discussion 8 we'll pass the gavel to -- for the record, I will call 9 you GE, GEH, GNF, and GNF-A. You let me know what I 10 mean by that. Please tell us what the name of your 11 company is and introduce yourselves.
12 MR. HALAC: Hello. My name is Kent Halac.
13 I work for Global Nuclear Fuels and GE Hitachi. I am 14 here today -- I am the lead licensing engineer for 15 fuel licensing at Global Nuclear Fuels. With me is 16 Scott Pfeffer from Global Nuclear Fuels, GE Hitachi 17 also. He is our technical lead in the area of 18 stability and control rod drop.
19 We appreciate you hearing this topic 20 today. We've come a long ways with this particular 21 methodology and we are looking forward to final 22 closure. We submitted the topical in February of 2018 23 and we had a detailed audit which was scheduled for 24 September 2018 but Hurricane Florence had something to 25 say about that and got delayed to October of 2018 and NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.
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10 1 was executed successfully subsequent to the hurricane 2 in Wilmington.
3 Scott Krepel has done an amazing job 4 digesting our technology and providing excellent 5 feedback on the content and narrowing it to be 6 appropriate and consistent with the draft guidance.
7 We have read and have digested the draft 8 SE associated with this and some of the feedback I've 9 received from our consulting engineers is it's 10 arguably the best SE he's every seen. We want to give 11 complements to Scott for his thorough detailed 12 approach toward this particular technology.
13 With that, I will yield to NRC.
14 CHAIR MARCH-LEUBA: I believe you're up.
15 MR. HALAC: Okay, that's right. Sorry.
16 MR. PFEFFER: I'm Scott Pfeffer. I'm the 17 technical lead for the radiological side of the 18 stability and radiological team at GNF GEH. Prior to 19 that I spent eight years on the stability and 20 radiological team mostly doing stability work previous 21 to that.
22 We'll get into the open items on the 23 control rod drop accident methodology. We'll start 24 off with a brief overview of the drivers and the 25 approach that we took in developing the LTR, and then NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.
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11 1 a brief discussion on the documentation status, so the 2 REIs, limitations and conditions, and the draft safety 3 evaluation.
4 Drivers, as has been previously mentioned, 5 were to align with the latest guidance from the staff 6 related to reactivity-initiated accident fuel damage 7 guidelines, specifically for CRDA for BWRs. The idea 8 was to more thoroughly evaluate possible CRDA 9 scenarios.
10 We also want to improve plant operations 11 to allow a person more flexibility than is currently 12 available under the old methodology which is a banked 13 position withdrawal sequence methodology. As part of 14 that, we've had some fuel changes and things, some 15 difficulties in start-up at plants, and one of those 16 is an inadvertent subcriticality event that can occur 17 so we wanted to allow some flexibility for that.
18 CHAIR MARCH-LEUBA: Subcriticality?
19 MR. PFEFFER: Subcriticality. The old 20 methodology has some generic requirements on banked 21 positions that must be met during the start-up and 22 mostly developed as part of older fuel designs. The 23 banked at four, which is right at the top of the fuel, 24 especially at BOC conditions, can have very little 25 worth.
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12 1 During the start-up if they are too slow 2 in pulling those rods, if they can't pull them fast 3 enough with zero worth as the reactor is heating up, 4 they can actually drop and become subcritical. That 5 happened at LaSalle, I believe it was. We wanted to 6 start to allow for flexibility in those banked 7 positions and that's part of the new methodology.
8 As part of that, also looking for 9 potential dose improvements, the goal for our LTR was 10 to demonstrate no fuel failures and that would allow 11 for some benefit in terms of the dose consequence for 12 control rod drop accident.
13 CHAIR MARCH-LEUBA: And this single rod 14 failure, is that the goal, or is it a requirement, or 15 99.9?
16 MR. PFEFFER: It is a requirement of the 17 methodology that we demonstrate as part of our 18 analysis that there are no failures.
19 The approach we used was to use previously 20 approved methods so that includes PANACEA or PANAC 21 which is our core simulator of PRIME or 22 thermal/mechanical methodology, and TRACG BWR systems 23 code to do our analysis.
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13 1 implemented were hydrogen efficient gas release models 2 and then the pellet-cladding mechanical interaction, 3 and high temperature cladding failure thresholds as 4 far as the acceptance criteria for rod failures.
5 Sources for that guidance were the 6 memoranda on the RAs and hydrogen pickup, as well as 7 SRP 4.2 Appendix B, as well as then supplemented by 8 Draft Guide 1327 as was mentioned previously.
9 Documentation. The LTR that was mentioned 10 was submitted in February 2018. We conducted the 11 audit in October 2018 and had good discussions there.
12 We resolved all RAIs in March 2019, again after some 13 back and forth and good resolution there.
14 LNC notification along with the draft SE 15 was issued in October with a final SE anticipated in 16 January 2020. At that point we would then issue the 17 approved version of the LTR in 2020 after receiving 18 the final SE.
19 As part of the LTR we also included the 20 required markups for GESTAR II, a General Electric 21 standard application for reactor fuel to allow us to 22 update GESTAR with approved modifications once the LTR 23 for CRDA is approved. Those modifications are part of 24 the LTR and will be part of the improvement.
25 That's all I have for the open session.
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14 1 Any questions?
2 CHAIR MARCH-LEUBA: Thank you to the 3 presenters. I have to confess while I was writing the 4 draft letter we issued in the full committee, I had 5 serious problems writing anything that was not 6 proprietary and that's why this presentation -- thank 7 you for having given us this.
8 Now we will proceed with the staff 9 presentation open. We are still in non-proprietary 10 session. You will need to turn on your mic.
11 MR. KREPEL: Good morning. I'm Scott 12 Krepel and you should all be familiar with me by now.
13 Just a quick reminder of my background. I graduated 14 from Purdue about 20 years ago now. I've had the 15 honor of studying under some of the former ACRS 16 members there.
17 Then I moved to TVA and I worked there as 18 a fuel engineer for about 10 years. Then I came to 19 the NRC where I've had experience in research, as well 20 as NRR doing licensing reviews for a lot of different 21 thermal-hydraulic events and accident events.
22 I'm sure that it may make it a little easier on 23 you that both of the presenters here today are named 24 Scott so here I am.
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15 1 started with my presentation doing a review of the 2 CRDA methodology for GNF. First quick background on 3 this. Previously NRC had guidance for the reactivity 4 initiated accidents for CRDA. Also control rod 5 ejection events for PWRs that was developed quite some 6 time ago. I believe several decades ago. That's 7 fairly old and obsolete at this point.
8 More research from facilities like NSRR in 9 Japan and CARI in France, among others, have provided 10 a lot more information and data on fuel failure during 11 this type of accident event which has led to interim 12 criteria and SRP 4.2 Appendix B which eventually we 13 hope Draft Guidance 1327 will replace and become a 14 permanent guidance for the foreseeable future.
15 Currently the GE methodology is based on 16 BPWS, as the other Scott mentioned earlier. Really 17 that is a generic analysis that is designed to look at 18 the limiting notch worth to determine whether a 19 problem is going to occur or not. This methodology, 20 this new methodology, provides an approach that can be 21 used to explicitly analyze different rod withdrawal 22 sequences and confirm whether they match the current 23 guidance.
24 Next slide. As you see, there are four 25 codes listed here that were used by GNF to be able to NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.
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16 1 do the analysis. I am not going to talk about TGBLA 2 again but I just have it there so you know it was a 3 cross section that goes to PANACEA. The other three 4 will be discussed further on as different models that 5 were used for direct CRDA analysis, or to provide a 6 bounding parameter for the input.
7 For the most part, we have already 8 validated a lot of the events of concern, but there 9 were some additional validation that needed to be done 10 that we needed to confirm the application of the cores 11 for the CRDA events and the cold conditions.
12 Next slide. I'm sure that you're familiar 13 with CRP 15.0.2 and that's the framework that we've 14 talked about before, but just a reminder that the last 15 two were not addressed explicitly. They were more 16 implicit as part of our review. If I looked at the 17 documentation and understood it, then I made the 18 finding that the documentation was sufficient. Those 19 are the asterisks for those last two.
20 Next slide. Before I talk about specific 21 areas and summarize that for the benefit of the 22 public, if there are any present, I wanted to go ahead 23 and summarize the regulatory acceptance criteria which 24 is outlined here on the slide. There's different SFR 25 50.34, but basically there's just a summary here of NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.
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17 1 the requirements.
2 First of all, you have to analyze CRDA 3 events and demonstrate that they are bounded by your 4 plant operations and those parameters. Secondly, if 5 a CRDA event happens, you have to look at the dose 6 consequence and it has to be within the design basis 7 limitation. Those are basically the two things that 8 summarize this slide.
9 Next slide, please. In SRP there are 10 specific criteria to demonstrate the regulatory 11 compliance as outlined here. There are interim 12 criteria, but Draft Guide 13.27 has very similar 13 criteria as well. GNF, as already mentioned, their 14 goal with this methodology is no fuel failure.
15 Out of those, it doesn't really matter to 16 GNF for their methodologies since they are going for 17 no fuel failure because then you don't have to worry 18 about the fission gas release and there would be no 19 change in any of the other things as well. We'll be 20 focusing on basically the first two criteria that are 21 listed there which is the high temperature cladding 22 failure.
23 Next slide. There are four areas from SRP 24 15.0.2 that I wanted to talk about. First is that the 25 licensee describes and characterizes the CRDA event NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.
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18 1 and identifies the key parameters, output parameters.
2 We've got NFLP for example.
3 NRC staff, me basically, compared their 4 description of the event to the parameters with other 5 PIRTs. For example, GNF did not include a formal PIRT 6 in their topical report, but they did include enough 7 information for me to be able to compare with other 8 vendors' PIRTs, a PIRT that the NRC even developed, 9 for example.
10 Question?
11 MEMBER REMPE: I do have a question.
12 Thank you for noticing. Again, if this is 13 proprietary, stop me. I know in your SE you did talk 14 about it wasn't quite a typical PIRT. Do you want to 15 elaborate or can you about why it differed?
16 MR. KREPEL: Sure. Typically a PIRT is a 17 more systematic approach where you identify a whole 18 list of specific phenomena that are of interest for 19 the accident. Then you assign them a value of either 20 high, medium, or low importance. That is consistent 21 with the NRC approach.
22 GNF didn't formally officially do that in 23 their topical report, but what they did do is provide 24 a description of the phenomena and how they addressed 25 the most important ones. NRC staff identified that NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.
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19 1 there were no other phenomena that would be important 2 for this event.
3 MEMBER REMPE: Thank you. That helps.
4 MR. KREPEL: Sure.
5 All right. Next slide. So for the code 6 assessment, as I mentioned earlier on an earlier 7 slide, most of the codes have already been analyzed 8 previously for code fidelity, thermal hydraulic 9 modeling for physics.
10 The only thing is the gap assessment and 11 looking at the cold conditions for reactivity 12 initiated accidents. That was the one little 13 difference. Also looking at the doppler feedback, for 14 example, in previous ones are the turbine trip events.
15 I did an assessment using the SPERT III test.
16 Next slide. For the CRDA evaluation 17 method, there are generally two areas that the NRC 18 staff review; looking at the modeling guidance and the 19 CRDA analysis procedure.
20 Next slide. For the modeling guidance, 21 basically you summarize all of the different 22 recommendations for the input parameters for the 23 modeling and how they model within the code to perform 24 the analysis. They are listed here on the slide and 25 these are generic categories.
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20 1 Next slide. Yes?
2 CHAIR MARCH-LEUBA: This is still non-3 proprietary but on the fission gas inventory, I assume 4 that information goes from PRIME. Correct?
5 MR. KREPEL: Prime is used to generate 6 some of the information that is used in the analysis.
7 CHAIR MARCH-LEUBA: But the real question 8 is, is it provided how much fission gas is in the 9 cladding in the gap, or the one that is inside the 10 oxide pellet?
11 MR. KREPEL: In the topical report 12 methodology, and I don't know if this is proprietary 13 or not, Scott.
14 MR. PFEFFER: I don't think so.
15 CHAIR MARCH-LEUBA: You need to talk in 16 the microphone. Sorry. Say your name.
17 MR. KREPEL: I'm just trying to avoid 18 proprietary information so just wanted to check in.
19 MR. PFEFFER: This is Scott Pfeffer. I 20 think that question is okay.
21 CHAIR MARCH-LEUBA: Okay.
22 MR. KREPEL: So the methodologies in PRIME 23 to calculate the fission gas that's within the gap, 24 but then it also does more work to then --
25 MR. PFEFFER: One second.
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21 1 CHAIR MARCH-LEUBA: Okay. Why don't we 2 propose this discussion to the proprietary section.
3 MR. KREPEL: Yeah, that's fine. I plan to 4 discuss it later anyway.
5 Okay. The next section really describes 6 how the actual analysis is performed once you've got 7 the model and then what the actual process is that's 8 done. It formulates basically the heart of the 9 method.
10 There are a lot of steps, step-by-step 11 description of what happens and how to specifically do 12 the controlled run withdrawal sequence and different 13 parameters that may affect the applicability of that 14 order. Of course, you evaluate that against the 15 acceptance criteria.
16 Next slide. The uncertainties. Again, 17 GNF did not do a formal PIRT, but they did identify 18 all of the important phenomena and addressed each one 19 of those for the uncertainties in different ways.
20 There are three listed here, the three 21 different approaches; the bounding analysis 22 parameters, the sensitivity studies, and the analysis 23 conservatism so seeing that conservatism in the 24 analysis. I will discuss all of that later in more 25 detail because most of is proprietary.
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22 1 CHAIR MARCH-LEUBA: In 20 seconds or less 2 would you describe the methodology as best estimate, 3 best estimate plus uncertainties, or conservative? A, 4 B, C?
5 MR. KREPEL: I would probably characterize 6 it as conservative.
7 CHAIR MARCH-LEUBA: Okay. In LOCA terms 8 would it be an Appendix K type calculation?
9 MR. KREPEL: Not exactly 100 percent 10 Appendix K but, yeah, it is conservative.
11 CHAIR MARCH-LEUBA: Thank you.
12 MR. KREPEL: I mean, Appendix K is very 13 conservative as you know.
14 Next slide. The final area was a little 15 unique to this topical report because, as you may 16 know, GNF has GESTAR II and they allowed the licensee 17 to adopt new methodology right away. They provided 18 updates to their GESTAR II to allow the licensee to 19 adopt new methodology. There are documentation 20 requirements that clarify how that methodology can be 21 used.
22 Jose, do you have a question?
23 CHAIR MARCH-LEUBA: I didn't turn on my 24 green light and he already could foresee my question.
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23 1 a one-minute primer on the GESTAR methodology.
2 How does it work? Specifically I'm 3 interested in if I am making a minor update to an 4 existing fuel; for example, I'm changing the inlet 5 filter or a major upgrade like GNF 13 by 13, how does 6 it propagate to a licensee? When does the licensee 7 need an LAR?
8 MR. KREPEL: First, with GESTAR II that is 9 the primary methodology that is documented and it 10 describes all of the other methods that can be used to 11 analyze the fuel. GNF does have a process for the new 12 fuel design and they can assess their new fuel design 13 and then document the details of what is called the 14 fuel compliance document which the NRC can audit at 15 any point. We did actually do an audit for GNF2 and 16 GNF1 fuel design if I recall correctly.
17 CHAIR MARCH-LEUBA: So a licensee on the 18 specifications have a reference to the GESTAR 19 document?
20 MR. KREPEL: Yes.
21 CHAIR MARCH-LEUBA: And then --
22 MR. KREPEL: The tech specs reference 23 GESTAR.
24 CHAIR MARCH-LEUBA: And then GE modifies 25 GESTAR only once, gets it approved through you, and it NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.
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24 1 applies to all the licensees. Is that correct?
2 MR. KREPEL: More or less, yes. They do 3 get approval and that includes all of the 4 modifications which is easy, but typically they submit 5 GESTAR amendment topical report that we also review to 6 confirm that everything is A-okay.
7 CHAIR MARCH-LEUBA: Once you issued an SER 8 Amendment 29, then every licensee that references 9 GESTAR can use the fuel. Is that correct?
10 MR. KREPEL: Yes.
11 CHAIR MARCH-LEUBA: Okay. Thank you.
12 MR. KREPEL: One last point here on this 13 final bullet point. As I mentioned, we'll talk about 14 it more later but there were some specific situations 15 where the requesting approval for the use of different 16 ways or methods to do the analysis. Those will be 17 subject to some limitations that we can discuss in 18 more detail later because, again, I don't want to run 19 into proprietary information.
20 Okay, next slide. So overall conclusions.
21 The staff found NEDE-33885P provided good guidance for 22 the use of GNF methodology to do CRDA analyses. We do 23 have four additional limitations and conditions beyond 24 those that already exist for the code that they're 25 using.
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25 1 I'll talk about those more in detail 2 later, but really they are just affirming the key 3 assumptions are met making sure that the method cannot 4 extend beyond the area of applicability that is 5 expected by the NRC staff when approving this method, 6 or when we plan to approve this method, I should say, 7 assuming that the ACRS is fine with it.
8 Yes.
9 MEMBER REMPE: I have a question. In your 10 SE you talked about the sensitivity of the results to 11 the high end of the enrichment spectrum. I assume 12 that was something near 5 percent. Could you confirm 13 that in the open session? Then how do I know that --
14 what would happen if GE came in with a higher enriched 15 fuel?
16 MR. KREPEL: I expect that kind of 17 situation would be addressed through their control rod 18 worth that explicitly says that is part of their 19 methodology for looking at whether they have higher 20 enrichment. Then that would lead to more release, 21 more heat release, and then that would be captured by 22 the control rod worth.
23 MEMBER REMPE: Just so I know what we're 24 approving if we approve this topical report, are we 25 approving its application for higher enrichment than NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.
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26 1 5 percent?
2 MR. KREPEL: I'm not explicitly approving 3 that but I'm not saying that it can't be used for that 4 purpose.
5 MEMBER REMPE: So then, again, I'm not 6 into how this process would work because I just know 7 that -- I'm more into the technical details, but how 8 does that get monitored and checked carefully if that 9 happens because, as you know, it's in discussion right 10 now.
11 MR. KREPEL: Probably the clearest answer 12 is right now PRIME in that methodology has its 13 limitation on burn-up and the applicability for that 14 method.
15 MEMBER REMPE: So for burn-up. What about 16 enrichment? Is it limited to 5 percent?
17 MR. KREPEL: Enrichment I can't recall 18 exactly. I know that with PANACEA there is an 19 assessment database that covers up to 5 percent but I 20 can't recall exactly if there is an explicit 21 limitation in there or not. Maybe GNF has an answer 22 to that.
23 MS. LAMB: This is Shawn Lamb from DNF.
24 We are looking it up right now.
25 CHAIR MARCH-LEUBA: Who was that? Sorry, NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.
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27 1 what's your name?
2 MS. LAMB: This is Shawn Lamb. I'm the 3 Manager of Stability and Radiological Analysis Team.
4 We are looking up if PRIME has an enrichment 5 limitation right now. We'll get back to you very 6 shortly.
7 CHAIR MARCH-LEUBA: Thank you.
8 MEMBER REMPE: I am interested in that.
9 I started asking that question to GE or GNF or whoever 10 we're talking to but also other --
11 MS. LAMB: Okay, thank you.
12 MEMBER REMPE: It sounds like the rules 13 might change and I just want to know if we're missing 14 something if the rules change. Thank you.
15 CHAIR MARCH-LEUBA: You know that ACRS 16 only speaks through letters so what we're hearing here 17 is subcommittee members opinions. I think even though 18 ACRS has not written a letter, we have made our ideas 19 very clear that if the enrichment is increased 5 20 percent, we would expect a very large review for 21 everybody in this building.
22 It wouldn't be -- all the technical 23 reports automatically apply. Even if you didn't say 24 specifically to apply 5 percent, I think it would be 25 a review of everything. That's what I would expect.
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28 1 MEMBER REMPE: Expectations. I'm just 2 curious so it's nice sometimes if someone can say, oh 3 yeah, some other method would limit this. Thank you.
4 MR. KREPEL: Understood. Understood.
5 That's a good statement.
6 CHAIR MARCH-LEUBA: We never made any 7 topical reports that says enrichment has to be granted 8 at 1 percent or 5, but if somebody comes up with a 9 natural reactor with .7 and it doesn't apply, you'll 10 have to review it if it's a big change.
11 MR. KREPEL: I know for the perspective on 12 this topical report, I know that I specifically 13 recognized and took a look that the way they 14 approached the applicability in looking at the 15 existing method that they used to analyze it and 16 whether there were any limitations on the methodology 17 would carry over into the new one for the CRDA 18 analysis.
19 MEMBER REMPE: Thank you.
20 CHAIR MARCH-LEUBA: Okay. So we managed 21 to recover all our technical difficulty time and we 22 are ahead of schedule. I would like to propose to 23 have a 10-minute break so we can switch to the closed 24 session. You are free to sit in your original chairs.
25 We are off the record --
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29 1 MEMBER REMPE: Public comments.
2 CHAIR MARCH-LEUBA: We are not off the 3 record because we need to ask for anybody in the room 4 who wants to provide a comment because this is the 5 opportunity in the public session.
6 Nobody in the room wants to make a 7 comment. How about the phone? If anybody is on the 8 phone line, could you please say hello to know that 9 it's open?
10 MR. HECK: Hello. This is Charles Heck of 11 GNF. We're hearing you. Can you hear me?
12 CHAIR MARCH-LEUBA: Yes, we can hear you.
13 Does anybody on the phone line have a comment? If so, 14 state your name and provide a comment. We waited a 15 full three seconds and nobody said anything. We will 16 assume we can close the public line now because we are 17 going to go into closed session. You're dismissed.
18 We're on a short recess.
19 (Whereupon, the above-entitled matter went off 20 the record at 9:29 a.m. and resumed at 9:40 for the 21 Closed Session.)
22 23 24 25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.
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Control Rod Drop Accident (CRDA) Application Methodology NEDE-33885P Review December 3rd, 2019
©2019 Global Nuclear Fuel - Americas, LLC.
ACRS Meeting / December 3, 2019, Rockville, MD
Contents for Open Portion Licensing Review
- Licensing Topical Report (LTR) Development Overview
- Drivers
- Approach
- Documentation Status
- Request for Additional Information (RAI)
- Limitations and Conditions (L&C)
- Draft Safety Evaluation (SE)
©2019 Global Nuclear Fuel - Americas, LLC.
ACRS Meeting / December 3, 2019, Rockville, MD 2
LTR Development Drivers
- Align with latest reactivity-initiated accident fuel damage guidelines
- More thoroughly evaluate possible CRDA scenarios
- Improve plant operations
- Allow for more flexibility during reactor startup
- Prevent inadvertent subcriticality events
- Dose Improvements
- Demonstrate zero fuel rod failures result from a CRDA
©2019 Global Nuclear Fuel - Americas, LLC.
ACRS Meeting / December 3, 2019, Rockville, MD 3
LTR Development (continued)
Approach
- Utilize previously approved methods
- PANAC, PRIME, and TRACG
- Implement NRC guidance
- Hydrogen and Fission Gas Release (FGR) models
- Pellet Cladding Mechanical Interaction (PCMI) and High Temperature Cladding Failure (HTCF) thresholds
- Sources for NRC guidance
- NRC Memoranda ML14188C423 (Reactivity-Initiated Accident Acceptance Criteria) and ML15133A306 (Hydrogen Uptake)
- NUREG-0800, Sections 4.2, including Appendix B, and 15.4.9
- DG-1327 (Control Rod Ejection and CRDA)
©2019 Global Nuclear Fuel - Americas, LLC.
ACRS Meeting / December 3, 2019, Rockville, MD 4
Current Status Documentation
- NRC audit conducted October 2018
- All RAIs resolved March 2019
- L&C notification October 2019
- Draft SE issued October 2019
- Final SE anticipated January 2020
- Update GESTAR-II expected February 2020
©2019 Global Nuclear Fuel - Americas, LLC.
ACRS Meeting / December 3, 2019, Rockville, MD 5
Scott Krepel Office of Nuclear Reactor Regulation, US NRC 1
=
Background===
NRC guidance for RIAs has evolved significantly in recent years SRP 4.2 Appendix B DG-1327 Current GNF/GEH methods are based on BPWS NEDE-33885P provides an approach better tailored to current guidance 2
=
Background===
NEDE-33885P only covers an analysis procedure; all codes have previously been reviewed and approved by the NRC TGBLA (lattice physics)
PANACEA (3D core physics)
TRACG (thermal hydraulics)
PRIME (fuel rod performance)
Additional validation performed to confirm applicability of codes to limiting CRDA events 3
Licensing Topical Report (LTR)
Review Components SRP 15.0.2 review areas (additional guidance in RG 1.203):
Accident scenario Code assessment Evaluation methodology Uncertainty evaluation Documentation*
Quality assurance*
- Implicitly addressed via GEH/GNF QA program and staff review of supporting documentation for this LTR 4
Regulatory Acceptance Criteria Current regulatory requirements are defined in:
10 CFR 50.34 - general safety analysis reporting requirement GDC 13 - system parameters must be controlled adequately to bound design basis accidents GDC 28 - reactivity accidents must not damage reactor coolant pressure boundary or impede core cooling 10 CFR 100.11, 50.67 - radiation dose limits 5
Regulatory Acceptance Criteria Current acceptance criteria to demonstrate regulatory compliance defined in SRP 15.4.9.II:
Reactivity initiated accident criteria (SRP 4.2 App. B)
High temperature cladding failure PCMI cladding failure Core coolability Fission product release inventory ASME reactor pressure vessel limit Note: DG-1327 contains updated criteria that are intended to supplant the current criteria; second public comment period ended October 2019 6
CRDA Accident Scenario Licensee characterized the CRDA scenario and relevant phenomena.
Critical output parameters are derived from acceptance criteria for CRDA event.
Identification of high importance phenomena is consistent with other available assessments for the CRDA or similar events.
7
CRDA Code Assessment Assessments from code LTRs Code fidelity Thermal hydraulics models Global core neutron kinetics response CRDA specific assessment SPERT III tests 8
CRDA Evaluation Methodology Different aspects of the CRDA analysis methodology described in the LTR were reviewed.
Modeling Guidance CRDA Analysis Procedure 9
CRDA Evaluation Methodology:
Modeling Guidance TRACG Model Nodalization Reactivity Insertion Fission Gas Inventory Initial Parameters Doppler Coefficient Enthalpy Determination 10
CRDA Evaluation Methodology:
Analysis Procedure At-Power & Cold Zero Power Analysis Parameters Control Rod Withdrawal Order Evaluation Against Acceptance Criteria 11
CRDA Uncertainties Uncertainties were dispositioned for individual phenomena known to be important for the CRDA event:
Bounding analysis parameters Sensitivity studies Analysis conservatism 12
GESTAR & Method Applicability GESTAR II updates to describe relevant documentation requirements (e.g., control rod withdrawal requirements)
Clarifications regarding how methodology can be used New NRC approved models and codes can be used in lieu of those described in the LTR, subject to certain limitations 13
Conclusions The staff found NEDE-33885P to provide adequate guidance for use of PANACEA and TRACG to perform CRDA analyses.
Limitations and conditions associated with approved LTRs for individual codes remain applicable Four additional limitations and conditions Confirm key assumption (control rod drop speed)
Restrictions on extended applicability of methodology 14
Nomenclature ASME - American Society of Mechanical Engineers BPWS - Banked Position Withdrawal Sequence CFR - Code of Federal Regulations CRDA - Control Rod Drop Accident DG - Draft Guide FGR - Fission Gas Release GDC - General Design Criteria GEH - General Electric - Hitachi GNF - Global Nuclear Fuel LTR - Licensing Topical Report NRC - Nuclear Regulatory Commission NSRR - Nuclear Safety Research Reactor PCMI - Pellet-Clad Mechanical Interaction RIA - Reactivity Initiated Accident RG - Regulatory Guide SPERT - Special Power Excursion Reactor Test SRP - Standard Review Plan 15
Backup Slides 16
Transient FGR Database Revised NSRR database shifted many data points and exposed a more prominent BU-dependence Large spread not unexpected, given spread in steady-state FGR data 17