ML23213A105
| ML23213A105 | |
| Person / Time | |
|---|---|
| Issue date: | 06/22/2023 |
| From: | Advisory Committee on Reactor Safeguards |
| To: | |
| References | |
| NRC-2448 | |
| Download: ML23213A105 (1) | |
Text
Official Transcript of Proceedings NUCLEAR REGULATORY COMMISSION
Title:
Advisory Committee on Reactor Safeguards Accident Analysis Thermal Hydraulics Open Session Docket Number:
(n/a)
Location:
teleconference Date:
Thursday, June 22, 2023 Work Order No.:
NRC-2448 Pages 1-39 NEAL R. GROSS AND CO., INC.
Court Reporters and Transcribers 1716 14th Street, N.W.
Washington, D.C. 20009 (202) 234-4433
NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.
(202) 234-4433 WASHINGTON, D.C. 20005-3701 www.nealrgross.com 1
1 2
3 DISCLAIMER 4
5 6
UNITED STATES NUCLEAR REGULATORY COMMISSIONS 7
ADVISORY COMMITTEE ON REACTOR SAFEGUARDS 8
9 10 The contents of this transcript of the 11 proceeding of the United States Nuclear Regulatory 12 Commission Advisory Committee on Reactor Safeguards, 13 as reported herein, is a record of the discussions 14 recorded at the meeting.
15 16 This transcript has not been reviewed, 17 corrected, and edited, and it may contain 18 inaccuracies.
19 20 21 22 23
1 UNITED STATES OF AMERICA 1
NUCLEAR REGULATORY COMMISSION 2
+ + + + +
3 ADVISORY COMMITTEE ON REACTOR SAFEGUARDS 4
(ACRS) 5
+ + + + +
6 SUBCOMMITTEE ON ACCIDENT ANALYSIS AND 7
THERMAL HYDRAULICS 8
+ + + + +
9 THURSDAY 10 JUNE 22, 2023 11
+ + + + +
12 The Subcommittee met via Teleconference, 13 at 1:30 p.m. EDT, Jose A. March-Leuba, Chair, 14 presiding.
15 16 COMMITTEE MEMBERS:
17 JOSE A. MARCH-LEUBA, Chair 18 RONALD G. BALLINGER, Member 19 VICKI M. BIER, Member 20 CHARLES H. BROWN, JR., Member 21 VESNA B. DIMITRIJEVIC, Member 22 GREGORY H. HALNON, Member 23 ROBERT MARTIN, Member 24 WALTER L. KIRCHNER, Member 25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1716 14th STREET, N.W., SUITE 200 (202) 234-4433 WASHINGTON, D.C. 20009-4309 www.nealrgross.com
2 JOY L. REMPE, Member 1
THOMAS ROBERTS, Member 2
MATTHEW W. SUNSERI, Member 3
4 5
ACRS CONSULTANT:
6 STEPHEN SCHULTZ 7
8 9
DESIGNATED FEDERAL OFFICIAL:
10 KENT HOWARD 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1716 14th STREET, N.W., SUITE 200 (202) 234-4433 WASHINGTON, D.C. 20009-4309 www.nealrgross.com
3 1
P-R-O-C-E-E-D-I-N-G-S 2
1:31 p.m.
3 CHAIR MARCH-LEUBA: The meeting will now 4
come to order. This is a meeting of the Accident 5
Analysis Thermal Hydraulics Committee. I am Jose 6
March-Leuba, the SC Chairman. In addition to in-7 person attendance at the NRC headquarters, the meeting 8
is broadcasted via MS Teams.
9 Members in attendance are Ron Ballinger, 10 Vicki Bier, Vesna Dimitrijevic, Greg Halnon, Bob 11 Martin, Matt Sunseri, and Charles Brown will be 12 joining us shortly. Our consultant is Steve Schultz.
13 He's also present.
14 Today, we are reviewing Framatome topical 15 report ANP-10339P entitled ARITA, ARTEMIS/RELAP 16 integrated transient analysis methodology. This 17 report describes a new statistical methodology 18 Framatome has developed for analyzing most transients 19 in pressurized water reactors.
20 This is a comprehensive methodology update 21 that require a very thorough safety evaluation and 22 final report by the staff. I am looking forward to 23 seeing the details from the topics today.
24 Portions of our meeting will be closed to 25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1716 14th STREET, N.W., SUITE 200 (202) 234-4433 WASHINGTON, D.C. 20009-4309 www.nealrgross.com
4 the public to protect Framatome proprietary 1
information.
2 We have not received requests to provide 3
comments, but we have an opportunity for public 4
comments before the beginning of the closed session of 5
the meeting.
6 The ACRS was established via statute and 7
is governed by the Federal Advisory Committee Act, 8
FACA. As such, the committee only speaks through its 9
published letter reports. The rules for participation 10 in all ACRS meetings were announced in the Federal 11 Register on June 13, 2019.
12 The ACRS section of the U.S. NRC public 13 website provides our charter, bylaws, agendas, 14 reports, and full transcripts for the open portions of 15 all full and subcommittee meetings, including the 16 slides presented there.
17 The designated federal official today is 18 Kent Howard.
19 A transcript of the meeting is being kept.
20 Therefore, speak into the microphones clearly and 21 state your name for the benefit of the court recorder.
22 And if you're in a conference room with multiple 23 people on the line, it includes the people in this 24 room, please remember to identify yourself regularly 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 for the accuracy of the transcript.
1 Please keep all of your electronics and 2
microphones on mute when not in use.
3 Gregory Suber of the staff will present 4
some introductory remarks. Greg?
5 MR. SUBER: Good afternoon. My name is 6
Gregory Suber and I am the deputy director of the --
7 (Audio interference.)
8 MR. SUBER: -- for this opportunity for 9
the staff to present its draft safety evaluation for 10 the Framatome ARITA topical report.
11 The staff will present their review of 12 important technical issues, findings, conclusions, and 13 limitations and conditions regarding ARITA. This 14 effort is the culmination of a significant amount of 15 work over the past four years.
16 We would like to express appreciation and 17 commend Framatome on its efforts to work with the 18 staff in resolving a significant number of technical 19 issues during numerous meetings, audits, and other 20 interactions.
21 The staff is approving the ARITA 22 statistical methodology that has been used to evaluate 23 SRP Chapter 15 non-LOCA events, including departure 24 from nucleate boiling, fuel centerline melt, transient 25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1716 14th STREET, N.W., SUITE 200 (202) 234-4433 WASHINGTON, D.C. 20009-4309 www.nealrgross.com
6 cladding strain, and primary and secondary system 1
pressure.
2 Framatome has indicated that they have 3
several customers who are ready to use ARITA and the 4
NRC staff expects to conclude their review very 5
shortly and issue a final SE, and we will hear more of 6
the interactions that we had with Framatome while the 7
staff does their presentation.
8 And with that, I'll turn the presentation 9
over to Framatome if they have any opening remarks.
10 CHAIR MARCH-LEUBA: Great, thanks, Greg.
11 So, we are now ready for the presentation. Alan 12 Meginnis of Framatome will present some opening 13 remarks and introduce the Framatome presenters.
14 Remember that this is the open section of 15 the meeting, which means the need for proprietary 16 information should be disclosed in the closed section.
17 So, Alan, just stay on the green light and talk 18 loudly.
19 MR. MEGINNIS: Okay, hi, I'm Alan 20 Meginnis, licensing manager for Framatome. Actually, 21 our vice president of fuel design, Steven Lydzinski, 22 is here today to provide opening remarks, but I wanted 23 to just give a special thanks to the ACRS.
24 I know that you guys juggled the schedule 25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1716 14th STREET, N.W., SUITE 200 (202) 234-4433 WASHINGTON, D.C. 20009-4309 www.nealrgross.com
7 at the last minute when we ran into some issues and 1
got us into this meeting --
2 (Audio interference.)
3 CHAIR MARCH-LEUBA: Thank you. Take over.
4 MR. LYDZINSKI: My name is Steven 5
Lydzinski. I'm the fuel engineering vice president at 6
Framatome. Good afternoon and welcome to all of those 7
attending our discussion today on Framatome's topical 8
report ANP-10339, the ARTEMIS/RELAP integrated 9
transient analysis methodology commonly referred to as 10 ARITA.
11 Framatome's objection is to get innovation 12 and improved performance methods to the industry. The 13 ARCADIA, COBRA-FLX, and GALILEO codes were submitted 14 and approved in the early 2010s, all of which have 15 been thoroughly benchmarked and validated.
16 ARITA demonstrates the value of coupling 17 these codes, proven transient simulator RELAP, and the 18 methodology that establishes improved confidence in 19 the fidelity of results that our customers can apply 20 to demonstrate compliance with all safety regulations 21 and requirements.
22 ARITA was created by a team of global 23 Framatome experts and dedicated staff that applied 24 decades of industry experience. Improvements in 25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1716 14th STREET, N.W., SUITE 200 (202) 234-4433 WASHINGTON, D.C. 20009-4309 www.nealrgross.com
8 modeling capabilities and advances in safety analysis 1
benchmarked the industry test data.
2 It was submitted for review in 2018 and 3
has undergone extensive NRC review. To date, there 4
were 19 audits and meetings conducted by the staff, 92 5
requests for additional information, and over 1,000 6
pages of additional information provided by Framatome 7
that supports the submitted topical.
8 Technical support for the staff's review 9
provided by a multi-discipline expert team at PNNL was 10 also part of the original review plan. This was seen 11 by Framatome as a positive recognition by the NRC to 12 supplement their skills with industry experts.
13 Over the last two years, PNNL contributors 14 have not been active in our discussions and it's not 15 quite clear how the PNNL review factored into the 16 final safety evaluation.
17 As the industry moves forward to embrace 18 improvements in modeling capabilities and computing 19 capabilities, it's prudent to carefully consider the 20 appropriate level and sources of conservatism.
21 Furthermore, it is vital to establish the appropriate 22 level of reasonable assurance of adequate protection.
23 While it may be easy to add additional 24 layers of conservatism in reaction to new approaches, 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
9 the benefits of advanced modeling approaches can 1
quickly be lost to the industry and the level of 2
assurance moves from reasonable assurance to 3
absolutely assurance, which is clearly not in the line 4
with the Commission's policy.
5 Throughout the review cycle, there have 6
been multiple exchanges with the NRC staff that have 7
resulted in many limitations and conditions that 8
further increased the level of conservatism, that 9
Framatome considers that many of the 28 limitations 10 and conditions go beyond reasonable assurance of 11 adequate protection.
12 For example, limitation and condition 18 13 and 19 require that an uncertainty be applied that is 14 two times the bounding value proposed by Framatome.
15 We must accept them at this time to advance the 16 industry forward and we will be evaluating the need 17 for a topical report supplement in the future.
18 Framatome is fully committed to the 19 nuclear industry and has continued to invest in the 20 development of our people and our technology. We 21 appreciate your time and welcome your questions, your 22 feedback, and your insights throughout this meeting.
23 Thank you.
24 CHAIR MARCH-LEUBA: Will you go ahead and 25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1716 14th STREET, N.W., SUITE 200 (202) 234-4433 WASHINGTON, D.C. 20009-4309 www.nealrgross.com
10 introduce your presenters?
1 MR. LYDZINSKI: Yes, joining me here today 2
we have Keith Maupin, one of the lead developers 3
through the methodology, and Mr. Buck Barner, who was 4
also one of the main contributors through the 5
development of the methodology. If you don't mind, 6
thank you very much.
7 CHAIR MARCH-LEUBA: And a reminder, just 8
so the court recorder recognizes your voice, say your 9
name at the beginning.
10 MR. BARNER: Thank you. This is Buck 11 Barner. I'm excited to be here today. I appreciate 12 everyone's time and willingness to be here as Alan 13 mentioned earlier, so I'm excited to share this with 14 everybody. It's a great step forward for us and I 15 look forward to presenting what we have here today.
16 If we go onto the next slide, for this 17 open session, just a quick overview of the agenda.
18 We'll do an overview at high level of what the topical 19 is, some background and history, the approval request 20 and the range of applicability of the topical, a few 21 key areas of interest, and end up with the summary.
22 So, what is ARITA? We already talked 23 about it, the ARTEMIS/RELAP integrated transient 24 analysis methodology. This defines a method for non-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
11 LOCA safety analysis for Chapter 15 events. It does 1
use a non-parametric statistical approach. Through 2
that, it makes a statistical statement for multiple 3
failures and merits, and using one of (audio 4
interference) approach to do that.
5 Through this process, we used SRP Chapter 6
15.0.2 guidance to develop this methodology and to 7
develop our evaluation models. That provided the 8
framework for the topical and how everything was 9
developed inside of there.
10 In addition to base topical that has the 11 Chapter 15 events, there are several other aspects 12 that are included in the topical, including mixed core 13 evaluations, power distribution control, set points 14 analysis to support the set points that remain outside 15 of the scope of typical non-LOCA methodology, and fuel 16 assembly reconstitution.
17 Just note that this does not include the 18 Chapter 15 control rod ejection analysis. This is in 19 a separate topical under AREA which has already been 20 approved.
21 CHAIR MARCH-LEUBA: ACRS has the custom of 22 interrupting you often and early, so let me ask a 23 question. When I look at ARITA, I see similarities 24 with the CSAU, code scaling, applicability, and 25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1716 14th STREET, N.W., SUITE 200 (202) 234-4433 WASHINGTON, D.C. 20009-4309 www.nealrgross.com
12 uncertainty analysis that has been in place since the 1
'80s. What are the main differences, if any? Do you 2
see the same similarities I do?
3 MR.
BARNER:
- Yeah, so there are 4
similarities between them. I think we did use a 5
different approach to it. There are pieces to it. We 6
do not follow that exact process, but there are 7
aspects to it that are built into this.
8 Because of the amount of data available to 9
us, there are some other different key pieces of that 10 I think you'll see throughout the presentation. I 11 don't know if, Keith, if there's anything you would 12 like to add to that?
13 MR. MAUPIN: Yeah, this is Keith Maupin.
14 The question may be touching on the CSAU and the 15 relationship to the Reg Guide 1.236 and the way LOCA 16 methodologies tend to build their evaluation models.
17 We definitely were aware of 1.236 as we 18 built this, but we felt like Chapter 15.0.2 was a set 19 of guidance that we were more equipped to use. So, we 20 don't have some of the test data that LOCA would have 21 to do separated effects testing on various phenomena 22 for non-LOCA application.
23 So,
- yeah, there are a
number of 24 similarities to it. We, in fact, consulted many of 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
13 the practices that are involved in that CSAU work.
1 CHAIR MARCH-LEUBA: My point on bringing 2
it is that this is not a new methodology. You are not 3
breaking group with a theory. It's basically we've 4
been applying this for 40 years, well, 30, so you're 5
just massaging and correcting a little bit here and 6
there, but basically it's nothing extraordinary, 7
right?
8 MR. MAUPIN: Yeah, I agree with most of 9
that. I think that I would say that what's really new 10 here with respect to the methodologies we've had in 11 the past is that we're replacing a point model 12 representation of the core during transient analysis 13 with a full 3D core and that's the big difference that 14 we're introducing with this. Sorry, and this was 15 Keith again just in case.
16 CHAIR MARCH-LEUBA: And for those in the 17 room here, we're having a problem with the mouse, with 18 the way it keeps popping up. All right, so let's 19 start with the presentation. We have only one 20 afternoon to go through 100,000 slides, so go for it.
21 MR. BARNER: I'll go faster. Just a quick 22 background and history, so at Framatome, we started 23 about the 2006 time frame is when we really began our 24 internal development on the new sets of codes and 25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1716 14th STREET, N.W., SUITE 200 (202) 234-4433 WASHINGTON, D.C. 20009-4309 www.nealrgross.com
14 methods. We talked about ARCADIA, and COBRA-FLX, and 1
GALILEO as our advanced codes that started this 2
effort, so around that time frame is when we started.
3 At the same time within history, around 4
the 2010 time frame is when there was an industry push 5
to replace those legacy codes and methods, so that was 6
a fortuitous time for us both in the industry and 7
internally to be working on this.
8 And with those two things going on, with 9
those motivations, our goal was to develop new 10 methodologies using our state-of-the-art modeling, 11 using our global expertise, and provide a
12 simplification of our topical reports that removed all 13 of the smaller topical reports and made one consistent 14 topical report. Ultimately, this was to facilitate 15 our future development and be able to prepare 16 ourselves for the future of the industry.
17 Just noting the AREA has been approved and 18 is using a very similar evaluation model, so as you 19 said, that's not particularly new here, so it is 20 something that's been seen before, but ARITA does 21 ultimately represent that final realization of the use 22 of our advanced codes and methods, and our commitment 23 to the industry to transition away from our legacy 24 codes and methods and provide our advanced codes and 25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1716 14th STREET, N.W., SUITE 200 (202) 234-4433 WASHINGTON, D.C. 20009-4309 www.nealrgross.com
15 methods.
1 (Simultaneous speaking.)
2 MR.
BARNER:
So,
- again, what's the 3
advantage of that? What advantage does that provide 4
to the industry? Through this better modeling, we 5
actually understand our plant behavior and understand 6
our responses and our safety margins better than we 7
have in the past.
8 So, this is value that we previously had 9
unavailable to us and we're hoping this opens up new 10 opportunities to the industry to use this value in 11 ways that we were unable to do in the past without 12 impacting the underlying safety margins, but better 13 understanding them.
14 So, this has allowed us to address things 15 like regulatory changes, Reg Guide 1.236, or any other 16 future regulatory changes that may be coming, allows 17 for increasing operating margins, power uprates, 18 things like core design authorization.
19 We're no longer having to design cores to 20 deal with conservatisms that were just part of the 21 method. We can optimize our core designs and things 22 like load follow, and looking forward to things like 23 advanced fuel management with increased directional 24 burn.
25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1716 14th STREET, N.W., SUITE 200 (202) 234-4433 WASHINGTON, D.C. 20009-4309 www.nealrgross.com
16 And so, really, none of these things are 1
one piece in themselves, but it's really what's most 2
important to the industry, what's most important to 3
the utility, and how we like to use this value that 4
allows us flexibility and options going forward.
5 So, really it's that higher fidelity 6
simulation that provides that understanding and 7
removes those excessive conservatisms that were built 8
into simplifying assumptions that allow us to provide 9
this value.
10 So, speaking of AFM, I believe the ACRS 11 has probably seen this slide before in the past, but 12 just looking forward to the future, if you look here, 13 there are some blue boxes and green boxes. Green 14 boxes are what we consider part of our advanced codes 15 and methods package and the blue boxes are what we 16 have as far as our existing methods.
17 So, as you see in the green boxes, we 18 talked about the previous codes with ARCADIA, GALILEO, 19 and COBRA-FLX, and now we have AREA, and ARITA over 20 there in yellow as the final unapproved piece of this 21 package, but with ARITA now, we have all of the final 22 building blocks of that foundation we need to move 23 forward with our AFM initiatives.
24 Just a little brief history and timeline.
25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1716 14th STREET, N.W., SUITE 200 (202) 234-4433 WASHINGTON, D.C. 20009-4309 www.nealrgross.com
17 So, we started having pre-submittals as early in 1
February of 2015 that resulted in the topical being 2
submitted in August of 2018.
3 Since August of 2018, there's been a lot 4
of interaction with the NRC through RAIs, additional 5
audits, meetings. We provided responses to the, 6
initial responses to all 92 RAIs in June of 2021, 7
though continued meetings and audits were held after 8
that and we supplied second final updated responses of 9
all RAIs on June of 2022.
10 Since then, we've continued to work with 11 the NRC, and we received the final set of draft LOCs 12 in March of this year and the draft SE was transmitted 13 in April of this year.
14 CHAIR MARCH-LEUBA: Since this is the 15 public portion of the meeting -- I apologize. The 16 mouse keeps clicking the right button on its own.
17 Since this is the public section of the meeting, I 18 wanted to clarify or maybe the staff can clarify 19 better for us that the staff does not provide a draft 20 SER to the vendor.
21 What they do is they send it to the vendor 22 for a proprietary check and factual errors, right?
23 So, it's not that we write the SER. By we, I mean the 24 staff doesn't write SERs in conjunction with the 25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1716 14th STREET, N.W., SUITE 200 (202) 234-4433 WASHINGTON, D.C. 20009-4309 www.nealrgross.com
18 vendor, but you have a chance to review it for factual 1
errors.
2 MR.
BARNER:
Thank you for that 3
correction. At a high level, so what is the approval?
4 It's for a non-LOCA Chapter 15 methodology, excluding 5
control rod ejection, but also includes these 6
different pieces for mixed core.
7 We talked about set points, but that 8
really boils down to the LPD LCO for CE plants and 9
core safety limit lines, power distribution control 10 methodology and fuel assembly reconstitution.
11 It's ultimately applicable to Westinghouse 12 two, three, and four-loop pressurized water reactors, 13 as well as CE designs. It was approved only for use 14 with approved CHF correlations, whether that's 15 currently approved or future approved. There are 16 wording in there that allow us to permit future 17 correlations into this once they are approved.
18 CHAIR MARCH-LEUBA:
And how about 19 different fuels, like chromium-doped, chromium-coated, 20 high enrichment, high burnup?
21 MR. BARNER: In general applicability, no.
22 So, it's for current fuel designs and I think the 23 wording is for evolutionary type fuel designs, but 24 anything that goes beyond that, there would be 25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1716 14th STREET, N.W., SUITE 200 (202) 234-4433 WASHINGTON, D.C. 20009-4309 www.nealrgross.com
19 separate type submittals, and that's why I say this 1
ultimately supports AFM, but through the AFM and 2
chromium-type things, those will need to be further 3
addressed.
4 CHAIR MARCH-LEUBA: Okay, thank you.
5 MR. BARNER: And, of course, they are 6
within the range of applicability constituent codes 7
that were used.
8 Here are some high level areas of 9
interest. We talked about the codes. One we have not 10 really mentioned yet is S-RELAP5. That is the system 11 thermal hydraulics code and that is now -- a big piece 12 to ARITA is that being coupled with the ARTEMIS nodal 13 simulator.
14 So, with these four codes, we've developed 15 three evaluation model variants. They are described 16 in the topical. One is that coupled system thermal 17 hydraulic with a neutronics model, and that's the main 18 piece of the topical, but there are two other 19 evaluation models, what we call the 0D system 20 transient system thermal hydraulic model, but we're 21 passing, similar to legacy methods, passing one 22 kinetics data from a neutron simulator to the system 23 thermal hydraulic marker in the static core model for 24 events that don't have a system response such as a 25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1716 14th STREET, N.W., SUITE 200 (202) 234-4433 WASHINGTON, D.C. 20009-4309 www.nealrgross.com
20 misaligned rod or a misloaded assembly.
1 How this is all accomplished is through 2
code coupling. It's that coupling between ARTEMIS and 3
S-RELAP5 that is used for all of the events that have 4
SAFDL-type limits and figures of merit break analysis 5
use for non-SAFDL-type figures of merit.
6 For the 0D, it is only used for non-SAFDLs 7
and then the static EM is applicable for SAFDLs, but 8
only for those events that do not have a system 9
thermal hydraulic response.
10 EM statistical approach, it is using Wilks 11 as the basis for the method. As I said earlier, it 12 does also account for multiple failures of merits 13 within a single event, and this approach is applied 14 for all three EM
- variants, not just (audio 15 interference).
16 And finally, we talked about this earlier 17 as well, the EM development. We followed the steps 18 based in SRP 15.02. That goes through and breaks down 19 into basically four major components of the scenario 20 identification process.
21 This provides us the roadmap when we look 22 through the events and decide what is the purpose of 23 the event, what are the figures of merit, what's 24 important to the event, what does it look like, and 25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1716 14th STREET, N.W., SUITE 200 (202) 234-4433 WASHINGTON, D.C. 20009-4309 www.nealrgross.com
21 how to perform the analysis.
1 This ultimately feeds a PIRT, or a PIRT 2
phenomenon identification and ranking were based on 3
that scenario identification. We look at the 4
important parameters that are needed to both model the 5
event and important to the figures of merit.
6 That ultimately feeds the next step which 7
is the assessment and matrix table were then based off 8
of that PIRT and the importance of the modeling. We 9
look at our EM variants and the constituent codes to 10 see if they are modeling everything properly.
11 And then based off of that, we ultimately 12 provide what we call the true and key parameters where 13 we account for the uncertainty treatment and identify 14 which is the appropriate EM model to be used within 15 the different transients.
16 So, just to summarize, it is a non-LOCA 17 methodology. It does represent a culmination of our 18 commitment to developing advanced codes and methods.
19 It is the final piece to that.
20 It provides that future looking forward to 21 areas such as AFM and only provides a single 22 consistent topical report covering multiple areas 23 related to plant safety, and tries to consolidate that 24 whole to a single topical that is consistent.
25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1716 14th STREET, N.W., SUITE 200 (202) 234-4433 WASHINGTON, D.C. 20009-4309 www.nealrgross.com
22 CHAIR MARCH-LEUBA: Thank you very much.
1 Any questions from the members, especially those in 2
the cloud? Hearing none, let's have the open 3
presentation by the staff.
4 (Pause.)
5 CHAIR MARCH-LEUBA: I'm not sure exactly 6
who is doing the talking, but whenever you're ready, 7
just start talking and introduce yourselves, and 8
again, so the court recorded recognizes your voice, 9
identify yourselves a couple of times. He only sees 10 one microphone here in the room.
11 MR. OTTO: Good afternoon. I'm Ngola 12 Otto, the project manager for this topical report 13 review. With me is Kevin Heller and John Lehning who 14 were the reviewers.
15 MR. LEHNING: Thank you, Ngola. So, my 16 name is John Lehning and it's our pleasure here to be 17 in front of the subcommittee. We're going to give you 18 a presentation here, our open presentation on the 19 ARITA topical report of the review the staff did.
20 With me, obviously, is Kevin Heller. I'll be giving 21 this portion of the discussion.
22 As the slide notes here, we had Pacific 23 Northwest National Laboratory as our consultant on 24 this review and I believe they will be dialing in at 25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1716 14th STREET, N.W., SUITE 200 (202) 234-4433 WASHINGTON, D.C. 20009-4309 www.nealrgross.com
23 some point maybe later on during the presentation.
1 They served as our consultant. They assisted us also 2
in drafting, providing input for our draft SE that it 3
was based on, so that's a little bit of how they 4
assisted in some of the review. So, onto the next 5
slide, please?
6 Okay, this, you know, obviously we have a 7
lot of slides to cover here in our safety evaluation, 8
based on the safety evaluation we did, which was 9
pretty thorough and covered so many things. We're 10 going to pick out some highlights here that we thought 11 would be of interest. We're going to go through some 12 of the introductory stuff quickly, but please stop us 13 if you have questions. Go ahead, Ngola.
14 Okay, so for the introduction, I think 15 Framatome did a good job explaining what the 16 evaluation model is. The only thing that I'll stress 17 on this slide is that the staff's review of ARITA 18 focused on the unique aspects of it.
19 And so, we didn't, in fact, do a real 20 review of codes like S-RELAP5 or GALILEO, ARTEMIS that 21 has been previously reviewed independently, but we did 22 look at things like the coupling of these together, 23 the calculational procedure, how the calculation is 24 done within ARITA, why it provides adequate assurance, 25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1716 14th STREET, N.W., SUITE 200 (202) 234-4433 WASHINGTON, D.C. 20009-4309 www.nealrgross.com
24 and then some of the uncertainty treatments, things 1
like the event-specific assessments, so that was 2
somewhat the focus of our review. Next slide?
3 So, this slide here, slide four, discusses 4
some of the key regulatory requirements and guidance 5
that governed the staff's review. There's a full list 6
in the safety evaluation. These are just highlights.
7 Among the key requirements are the general 8
design criteria in Appendix A to 10 CFR 50. GDC 10 9
covers fuel integrity, specified acceptable design 10 limits or SAFDLs. GDC 15 covers pressure boundary of 11 the RCS and things like over-pressurization and so on.
12 There are a number of those.
13 The technical specifications in 50.35, 14 those are important because the safety analysis and 15 the allowable operating domain need to have an 16 alignment together, and we'll go through that in a 17 little bit more detail later on.
18 The dose limits come into play because for 19 accidents, the number of fuel failures that can be 20 tolerated is ultimately a function of what the dose 21 limits are for those events.
22 And as far as guidance goes, the standard 23 review plan Chapter 15 has guidance on how to develop 24 evaluation models, or how the staff ought to review 25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1716 14th STREET, N.W., SUITE 200 (202) 234-4433 WASHINGTON, D.C. 20009-4309 www.nealrgross.com
25 those, I'm sorry, as well as different guidance for 1
the review of different types of events that the SRP 2
covers, and we'll show you a slide of what those 3
different event categories are later.
4 And then finally, the EMDAP, which we have 5
spelled out on the slide, in Regulation Guide 1.230 6
was used to sort of structure some of the parts of the 7
safety evaluation and make sure it was comprehensive 8
to the types of expectations there in that guidance.
9 Okay, so the next slide here goes into a 10 little bit of the review history, and so I'm going to 11 talk about this at a little bit of a high level.
12 There's a lot of detail on this slide, but 13 I think just first off, this ARITA review was one of 14 the most complex, challenging, and intense reviews 15 that Kevin and I have been a part of, and I've worked 16 at the agency over 20 years now.
17 It's not only because of first-of-a-kind 18 issues in applying this technique that was mentioned 19 based on the original CSAU, but applying it to a much 20 wider set of events for the first time and some of the 21 challenge with getting the data that's necessary for 22 that.
23 I think also ARITA tends to compress down 24 what was originally other independent free-standing 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
26 topical reports into certain chapters in that method, 1
so it really brings a lot of different things together 2
in a confluence of things, and there are a whole lot 3
of intricacies in the calculational process as well.
4 But I think one of the main challenges, 5
and Ngola, if you could advance the slide maybe one 6
time there, that I'll just talk about at a high level, 7
so there was quite a lot of information that needed to 8
be reviewed, and so when we first did the acceptance 9
review, the staff noted that there was some missing 10 information and also some items where the position 11 Framatome was coming in with, we weren't sure that it 12 would ultimately meet regulatory acceptance criteria.
13 And so, all of those things were made 14 clear. The decision was made based on consultation 15 with Framatome to proceed with the review and then 16 they would try to address the issues during the 17 review.
18
- Okay, but we didn't have enough 19 information really at the beginning, at the get-go to 20 even sort of draft the SE or to know which direction 21 some of these things were going to turn out with, and 22 it took quite a bit of time, I think, to resolve a 23 number of the RAIs.
24 You can see that orange bar extends 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
27 probably two and a half years. Normally, we might be 1
talking about six to nine months, maybe a year, but 2
this took quite a bit of time.
3 And really by the time I think we got the 4
final initial response in May 2021, we started to get 5
enough information where we could really start 6
understanding the direction this was going and start 7
working on the safety evaluation, but even come June 8
2022, there were still quite a number of updates.
9 And I think Framatome alluded to the 10 amount of work that they did. It was probably 1,600 11 pages of material there that was submitted at that 12 time. I think probably about three-quarters of the 13 RAI responses were updated and changed.
14 So, this was almost like, I don't want to 15 say a new review because we had been working with them 16 throughout, and we note there the number of audits and 17 meetings that we participated in, but it certainly 18 took quite a lot of time to review that information.
19 And I think that's part of why we weren't 20 able at that point in time to have further dialogue 21 with Framatome, and they did note a couple of 22 limitations that came out of that phase of the review, 23 but in order to sort of make the deadline, we couldn't 24 continue to interaction with them.
25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1716 14th STREET, N.W., SUITE 200 (202) 234-4433 WASHINGTON, D.C. 20009-4309 www.nealrgross.com
28 We made the decision based on what was on 1
the docket and what gave us reasonable assurance at 2
this time. It's not to say that with more information 3
or had the review been differently, we couldn't have 4
gotten to a different conclusion, but we ended up 5
where we are based on that part of the review process.
6 CHAIR MARCH-LEUBA: Let me ask you, 7
interrupt for a moment.
8 MR. LEHNING: Sure.
9 CHAIR MARCH-LEUBA: I have to stipulate 10 that this is the most complex and biggest review I 11 have seen in all my years working in this area, but, 12 and everyone complains that the 100 RAIs these teams 13 are using.
14 Now, in your opinion, the reason for the 15 large number of RAIs was a deficiency on the original 16 submittal that was not sufficiently detailed to reach 17 a conclusion or was it because this code was so large 18 that we had to cover a lot of area?
19 MR. LEHNING: Yeah, probably mostly the 20 latter. I think it just was a very complex 21 methodology. There's no doubt about that. Framatome 22 put a lot of work into developing it.
23 I think they also had a different idea of 24 what that method ought to look like, and the idea that 25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1716 14th STREET, N.W., SUITE 200 (202) 234-4433 WASHINGTON, D.C. 20009-4309 www.nealrgross.com
29 they had at the get-go was that there would be a lot 1
of flexibility for them to decide things on an 2
individual plant analysis level, and then the staff 3
said, well, during the review, we sort of talk 4
through.
5 That might take away some of the 6
efficiency because if we've got to review all of the 7
different choices you're making on each one of these 8
plant reviews, what do we gain by doing this generic 9
review up front? And so, they revised that and 10 somewhat to sort of address that critique.
11 And so, I don't want to say the word 12 deficiency, but I do want to say they had a different 13 vision of what the end product would look like than 14 the staff did.
15 CHAIR MARCH-LEUBA: Thank you.
16 MR. LEHNING: So, I think we can go on.
17 DR. SCHULTZ: Excuse me, John.
18 MR. LEHNING: Oh, sorry.
19 DR. SCHULTZ: I just want to follow up on 20 that. So, the number of RAIs, they were issued in a 21 fairly short range of time. Most of those or many of 22 those were because of this different approach where 23 you were looking for a generic evaluation versus to go 24 beyond a plant-specific, or not to go to a plant-25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1716 14th STREET, N.W., SUITE 200 (202) 234-4433 WASHINGTON, D.C. 20009-4309 www.nealrgross.com
30 specific evaluation in the future?
1 MR. LEHNING: There's a certain number of 2
them that I would say that fall in that category. It 3
is very complex and I think a number of them were for 4
clarification. Maybe there were a few where we 5
thought there were things missing, but I think -- and 6
then some of them had to do with some other things 7
that we'll get into maybe more in the closed session.
8 I don't want to --
9 DR. SCHULTZ: That's fine. Thank you.
10 MR. LEHNING: And then this last slide, I 11 don't think we plan to go over now. We'll repeat it 12 in the closed presentation after we've given you some 13 more of the detail that will help justify these 14 points, so.
15 CHAIR MARCH-LEUBA: One of the reasons for 16 ACRS to exist is to give confidence to the public that 17 we, an independent body, are looking over these 18 shoulders. So, this is the only part of the 19 presentation that the public will read, so do tell us 20 what the conclusions are.
21 MR. LEHNING: Certainly, then so the 22 staff's conclusions, which we'll go into a little bit 23 more of the basis for in the closed presentation, but 24 the staff found ARITA methodology acceptable for 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
31 modeling the events that are within the scope of the 1
method in SRP Chapter 15, including all of the 2
evaluation model variants, the coupled, the static and 3
the 0D, as well as the associated calculational 4
process and the methodology for doing the statistical 5
uncertainties.
6 Staff also found the supplementary 7
evaluation model features that are talked about in the 8
closed presentation in Section 3.8 of our safety 9
evaluation, we found those acceptable.
10 Obviously, the staff's conclusions are 11 predicated upon a couple of things here, that the 12 method is being used within this range of 13 applicability, and that's defined in the topical 14 report Section 13, as well as licensees acceptably 15 addressing the staff's limitations and conditions in 16 Section 5.2 of our safety evaluation.
17 CHAIR MARCH-LEUBA: And since you brought 18 up the limitation and conditions, which is the meat of 19 the review, this also, the same way there was a large 20 number of RAIs, I saw a large number of limitations 21 and conditions.
22 In the open session, can you summarize not 23 what the 28 were, but some were applicability range, 24 some where the product of uncertainty? Can you give 25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1716 14th STREET, N.W., SUITE 200 (202) 234-4433 WASHINGTON, D.C. 20009-4309 www.nealrgross.com
32 us a high level flavor or you're not prepared to do 1
that?
2 MR. LEHNING: I think it's difficult. I 3
would say it is from a wide variety of things, that 4
some of them are from uncertainty items, very specific 5
things like on this uncertainty parameter, staff 6
reviewed it differently and saw that that range ought 7
to be different.
8 And then there are some where we're 9
attempting to ensure licensees submit enough 10 information in the license amendment request process 11 that we could have assurance that we know how they 12 implemented the methodology in that plant-specific 13 detail, and there are some where, yeah, just a number 14 of other different categories probably that are hard 15 to characterize.
16 CHAIR MARCH-LEUBA: In my experience, I'm 17 not scared by a large number of limitations and 18 conditions if they are well-established and well-19 described, and
- indeed, they remove regulatory 20 uncertainty at the license amendment request stage 21 because it sets up the rules of the game. Thou shalt 22 do this. Thou shalt do that. And so, I don't have 23 any problem with the number. The question maybe I 24 should have asked Framatome is can they live with 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
33 that? Do they think they're okay?
1 MR. LEHNING: Yeah, Ngola, could you go 2
back to the slide on the review timeline? Because I 3
just will just say one more thing about that, and I 4
think during the review, and we have one point there 5
on perspective, L&Cs first discussed in December 2020.
6 And so, we tried as early as possible 7
where we foresaw a potential limitation condition to 8
raise that during the review, and a number of them, we 9
did get I would say grudging acceptance that we can 10 live with this one even though it may not be what we 11 originally wanted.
12 Now, as I said, there were a few, and 13 Framatome pointed out 18 and 19, but there were a 14 couple more that came in this final phase of the 15 review where there was no more opportunity for 16 interaction and basically we had to go with whatever 17 we had on the docket there, and just a few of them 18 that they want to come back in the future and come 19 back to.
20 CHAIR MARCH-LEUBA: I mean, it is our 21 intention to issue -- the SER that we have reviewed, 22 that ACRS has reviewed is final as far as you're 23 concerned?
24 MR. LEHNING: It will become final after, 25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1716 14th STREET, N.W., SUITE 200 (202) 234-4433 WASHINGTON, D.C. 20009-4309 www.nealrgross.com
34 yeah, this meeting --
1 (Simultaneous speaking.)
2 CHAIR MARCH-LEUBA:
There's always 3
conformance edits and one will always have some 4
comments here and there.
5 MR. LEHNING: Right, it's not our intent 6
to revise a number of things based on further dialogue 7
and interaction between us and Framatome before 8
issuing the final.
9 CHAIR MARCH-LEUBA: But the path forward 10 for the areas of dissent, since they brought it out, 11 limitations 18 and 19, will be for Framatome to 12 provide additional information in the supplement, or 13 a letter, or something, and you will be able to turn 14 it around quickly?
15 MR. LEHNING: We'll go through in the 16 closed session a little bit more. We have a slide on 17 that.
18 CHAIR MARCH-LEUBA: I know.
19 MR. LEHNING: Okay.
20 CHAIR MARCH-LEUBA: But this is the open 21 session.
22 MR. OTTO: This is Ngola Otto. We're 23 still in discussion with Framatome with respect to 24 that, so we'll know more in the coming weeks and 25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1716 14th STREET, N.W., SUITE 200 (202) 234-4433 WASHINGTON, D.C. 20009-4309 www.nealrgross.com
35 months what, in fact, it's going to be on the --
1 CHAIR MARCH-LEUBA: We need to have -- if 2
this is an area of disagreement, we need to have a 3
path forward for resolution, and, I mean, ACRS can be 4
completely silent on this issue, but knowing that it's 5
a problem, we need to say something in our letter.
6 MR. LEHNING: And, I think, yeah, the 7
slide that we talk about will talk about it from a 8
technical standpoint. There are some logistical 9
details like what's the best path forward that 10 compromises everybody's interests in the right way?
11 That's still being worked out though.
12 CHAIR MARCH-LEUBA: My personal problem is 13 I have to write a draft ACRS letter for this July full 14 committee to discuss with the committee and we can 15 write proprietary letters, but we've never done it in 16 the seven years I've been here, so I would rather it 17 be a non-proprietary letter.
18 So, certainly we'll go through review on 19 whatever I provide, but anything that I can say non-20 proprietary would help.
21 MR. OTTO: So, we've had discussions with 22 respect to probably an additional submittal that we'll 23 address later in a separate review.
24 CHAIR MARCH-LEUBA: And you can turn it 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
36 around relatively quickly?
1 MR. OTTO: Right, that's the plan.
2 CHAIR MARCH-LEUBA: Because I don't know, 3
but typically, power plants order fuel in the spring, 4
so we have ten months until the next reload. So, I'm 5
sure Framatome would like to get some conclusion, some 6
finality on what they are looking to do.
7 MR. OTTO: Okay.
8 (Simultaneous speaking.)
9 MR. SUBER: This is Gregory Suber. So, 10 what I wanted to say is that the NRC and Framatome 11 have aligned on the current draft safety evaluation 12 report, and that safety evaluation report will be sent 13 to Framatome for their dash A read and approval and 14 that's what we're bringing before the committee today.
15 CHAIR MARCH-LEUBA: Yes.
16 MR. SUBER: So, from this perspective, we 17 have a current resolution with this version of what we 18 have agreed upon for all of the limitations and 19 conditions.
20 CHAIR MARCH-LEUBA: And if I --
21 MR. SUBER: Now, if Framatome in the 22 future decides to submit additional information, then 23 that would result in a Rev. 1, correct --
24 CHAIR MARCH-LEUBA: Or supplement.
25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1716 14th STREET, N.W., SUITE 200 (202) 234-4433 WASHINGTON, D.C. 20009-4309 www.nealrgross.com
37 MR. SUBER: -- or that would result in a 1
revision of the approved NRC --
2 CHAIR MARCH-LEUBA: And the SER that the 3
staff will issue within the next couple of months or 4
maybe earlier can be used -- if I'm a licensee that 5
wants to buy fuel for them next spring, they can use 6
this SER?
7 MR. SUBER: They can use it, yes, they 8
can.
9 CHAIR MARCH-LEUBA: Framatome, do you want 10 to make some comments?
11 MR. LYDZINSKI: Yeah, this is Steve 12 Lydzinski here.
13 CHAIR MARCH-LEUBA: Speak up.
14 MR. LYDZINSKI: Yeah, sorry. So, we have 15 discussed this particular limitation and condition 16 earlier this week. While the uncertainty proposed in 17 the limitation and condition is conservative, we do 18 need to move forward with that conservative value.
19 We've discussed different options, whether 20 it be a formal letter, whether it be the topical 21 report supplement, or some other licensing action that 22 further reduces the very conservative value proposed 23 in that limitation and condition, but it's something 24 we need to assess in terms of time and effort and the 25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1716 14th STREET, N.W., SUITE 200 (202) 234-4433 WASHINGTON, D.C. 20009-4309 www.nealrgross.com
38 impact to the safety studies, but certainly the value 1
input by the limitation and condition is conservative.
2 CHAIR MARCH-LEUBA: Right, because you can 3
always issue a change during the licensing amendment 4
request, but that's decidable because it's regulatory 5
uncertainty.
6 MR. LYDZINSKI: Correct.
7 CHAIR MARCH-LEUBA: Okay, so thank you for 8
placing all of this discussion in the open record so 9
I can write my letter. This is why I wanted to have 10 it here. So, any questions from the members, 11 including those in the cloud? No questions?
12 Since this is going to be the end of the 13 open session, we'll give an opportunity to any members 14 of the public to place comments on the official 15 transcript. If there is a member of the public that 16 wants to issue a comment, please do so now. No?
17 MR. NEVLING: Okay, I'll give you one, Jim 18
- Nevling, manager for special projects with 19 Constellation Energy Generation in the nuclear fuels' 20 organization.
21 We do intend to adopt ARITA methods into 22 our licensing basis for Byron and Braidwood Stations 23 in the relatively near future, and we very much 24 appreciate NRC's hard work and support for this, and 25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1716 14th STREET, N.W., SUITE 200 (202) 234-4433 WASHINGTON, D.C. 20009-4309 www.nealrgross.com
39 we look forward to timely completion and issuance of 1
the SER.
2 CHAIR MARCH-LEUBA: Thank you very much.
3 Any more comments from the public? So, Jim, can you 4
lower your hand? Thank you. So, I don't hear any 5
more comments. We are done with the open portion of 6
the meeting. We are going to close this line and will 7
not come back to this phone line at all this week.
8 Anybody that belongs in the closed 9
session, you have the number and you can call in 10 within the next ten minutes. Let's take a short break 11 until 2:25 Eastern to set up the thing. So, the open 12 session of the meeting is closed.
13 (Whereupon, the above-entitled matter went 14 off the record at 2:15 p.m.)
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
1 ARITA - ARTEMIS/RELAP Integrated Transient Analysis Methodology - Barner and Maupin - ACRS Subcommittee, 6/22/2023 ARITA ARTEMIS/RELAP Integrated Transient Analysis Methodology Buck Barner and Keith Maupin ACRS Subcommittee, June 22, 2023
2 ARITA - ARTEMIS/RELAP Integrated Transient Analysis Methodology - Barner and Maupin - ACRS Subcommittee, 6/22/2023 Agenda Approval Request and Range of Applicability Key Areas of Interest Background and History Overview Summary
3 ARITA - ARTEMIS/RELAP Integrated Transient Analysis Methodology - Barner and Maupin - ACRS Subcommittee, 6/22/2023 Overview
ARITA - ARTEMIS/RELAP Integrated Transient Analysis Methodology
Defines a methodology to analyze non-Loss-of-Coolant (non-LOCA) events
Uses a non-parametric statistical approach to make a 95/95 statistical statement for each figure of merit (FOM) using a Monte Carlo approach
Standard Review Plan (SRP) Chapter 15.0.2 was used as guidance in development of the method
Addresses mixed core, power distribution control, setpoints and fuel assembly reconstitution
Excludes Control Rod Ejection (CRE) which is analyzed using AREA - ARCADIA Rod Ejection Accident Topical Report
4 ARITA - ARTEMIS/RELAP Integrated Transient Analysis Methodology - Barner and Maupin - ACRS Subcommittee, 6/22/2023 Background and History
In 2006, Framatome began the development of a new set of advanced PWR codes
ARCADIA (ANP-10297PA, Revision 0 and Supplement 1, Revision 1)
Includes the 2D cross section code APOLLO-2A and the 3D nodal code ARTEMIS
COBRA-FLX (ANP-10311PA, Revision 1)
GALILEO (ANP-10323PA, Revision 1)
Around the same time (2010) there was a push in the industry to replace legacy methods
The goal was to develop new methodologies that:
Use state of the art modeling
Take advantage of best practices from US, French and German experience
Simplify topical report interdependences and reduce the number of topical reports
Facilitate future method development
AREA (ANP-10338PA, Revision 1) was the first methodology topical approved.
ARITA represents the realization of Framatomes goal of advanced codes and methods.
5 ARITA - ARTEMIS/RELAP Integrated Transient Analysis Methodology - Barner and Maupin - ACRS Subcommittee, 6/22/2023 Background and History
What advantage does this provide to the industry?
Better modeling of the actual plant behavior leads to better understanding of plant response and the actual safety margins.
Value (or margins) that were previously unavailable open new opportunities for the industry without impacting the underlying safety margins established by the regulations
Address Regulatory Changes (e.g., RG 1.236)
Operating Margins
Core Design Optimization
Load Follow
Advanced Fuel Management (AFM) - Increased Enrichment and High Burnup
Whatever is most important to the utility!
Higher fidelity simulations and modeling provides increased understanding of plant response and allows reduction in the excessive conservatism associated with simplifying assumptions in lower fidelity legacy methods
6 ARITA - ARTEMIS/RELAP Integrated Transient Analysis Methodology - Barner and Maupin - ACRS Subcommittee, 6/22/2023 Background and History Fuel Performance GALILEO ANP-10323PA,R1 LOCA RLBLOCA EMF-2103PA,R3 SBLOCA EMF-2328PA,R0 & Sup 1 PA GALILEO in LOCA ANP-10349PA,R0 Non-LOCA AREA ANP-10338PA, R0 ARITA ANP-10339P M5Framatome Cladding BAW-10227P, R2 Neutronics ARCADIA ANP-10297PA, R1 & Sup 1PA Rod Bow XN-NF-75-32PA Fuel Mechanical and Structural Fuel Design GAIA ANP-10342PA,R0 & Q12 ANP-10334PA,R0 External Loads ANP-10337PA,R0 and Sup 1PA,R0 Liftoff BAW-10243PA,R0 Cladding Collapse BAW-10084PA,R3 Core TH COBRA-FLX ANP-10311PA, R1 Only major methodology connections shown
7 ARITA - ARTEMIS/RELAP Integrated Transient Analysis Methodology - Barner and Maupin - ACRS Subcommittee, 6/22/2023 Background and History
Pre-submittal meetings held February 2015, June 2016, and July 2017
The ARITA Topical Report was submitted August 2018
A post-submittal acceptance meeting was held November 2018
The first set of RAIs (1-13) were transmitted to Framatome December 2019
Supplemental information was transmitted to the NRC March 2019 in response to the post-submittal meeting
Responses to RAIs 1-13 were transmitted to the NRC April 2020
Additional RAIs (14-92) were transmitted to Framatome April 2020
Responses to RAIs 14-92 were transmitted to the NRC in 3 separate submittals July 2020, November 2020 and June 2021
Audit and meetings were held during this time to aid in the review of the RAI responses
Audits and discussions continued through April 2022
Final updated responses to all RAIs to address reviewer comments were transmitted to the NRC June 2022
The final set of draft L&Cs was transmitted to Framatome March 2023
The Draft SER was transmitted to Framatome April 2023
8 ARITA - ARTEMIS/RELAP Integrated Transient Analysis Methodology - Barner and Maupin - ACRS Subcommittee, 6/22/2023 Approval Request and Range of Applicability
Non-LOCA Chapter 15 methodology, excluding CRE
Mixed Core Method
Local Power Density Limiting Condition of Operation (LPD LCO) and Core Safety Limit Lines (CSLL)
Power Distribution Control (PDC)
Fuel Assembly Reconstitution
Applicable to Westinghouse (2-, 3-, and 4-loop) Pressurized Water Reactor (PWR) designs and Combustion Engineering (CE) PWR designs
Use of approved Critical Heat Flux (CHF) correlations
Within the range of applicability of the constituent codes (ARTEMIS, S-RELAP5, COBRA-FLX, GALILEO)
9 ARITA - ARTEMIS/RELAP Integrated Transient Analysis Methodology - Barner and Maupin - ACRS Subcommittee, 6/22/2023 Key Areas of Interest - Evaluation Model (EM) Description
Constituent codes
ARTEMIS - 3D nodal simulator code previously approved in ANP-10297
COBRA-FLX - Subchannel core thermal-hydraulics code previously approved in ANP-10311
GALILEO - Fuel performance code previously approved in ANP-10323
S-RELAP5 - System thermal-hydraulics code previously applied in EMF-2310
EM Variants
There are 3 EMs described in the ARITA topical:
1)
Coupled system-thermal hydraulic and neutronics model, 2) 0D system thermal-hydraulic model, and 3)
Static core evaluation model.
Code Coupling
In the Coupled EM, ARTEMIS and S-RELAP5 are coupled together to solve time-dependent multi-physics problems (Specified Acceptable Fuel Design Limits (SAFDLs) and non-SAFDL FOM)
In the 0D EM, point kinetics data generated in ARTEMIS is to provided the S-RELAP5 (Non-SAFDL)
In the Static EM, ARTEMIS is used for events that do not require a system thermal-hydraulic solution (SAFDL)
Statistical Approach
Non-parametric approach based on the Wilks method is used to make a statistical statement on the FOM.
Account for multiple FOM.
The statistical approach is used for all 3 EM variants described above.
10 ARITA - ARTEMIS/RELAP Integrated Transient Analysis Methodology - Barner and Maupin - ACRS Subcommittee, 6/22/2023 Key Areas of Interest - EM Development
The EM development process used the following development steps (based on SRP 15.0.2)
Scenario Identification Process-Provides and roadmap to perform a non-LOCA event evaluation including 1) the purpose of the analysis 2) the event scenario and 3) the event analysis.
Phenomena Identification and Ranking Table (PIRT) - Establishes important parameters and conditions for each event analysis based on their importance to modeling the event and their impact on the FOM.
Assessment Matrix Table (AMT) - Assesses the capabilities of the EM variants and constitute codes to appropriately model the given event.
Treatment of Parameters - Using the Scenario Identification Process, PIRT and AMT, the key parameters and uncertainty treatments are identified and used in the appropriate EM variant.
11 ARITA - ARTEMIS/RELAP Integrated Transient Analysis Methodology - Barner and Maupin - ACRS Subcommittee, 6/22/2023 Summary ARITA Is a Non-LOCA (excluding CRE) method applicable to CE and Westinghouse Plants Represents the culmination of Framatome's commitment to developing advanced codes and methods Provides the foundation for future development in areas such as AFM Is a single, consistent topical report that cover multiple areas related to plant safety analysis
12 ARITA - ARTEMIS/RELAP Integrated Transient Analysis Methodology - Barner and Maupin - ACRS Subcommittee, 6/22/2023 Acronyms AFM - Advanced Fuel Management AMT - Assessment Matrix Table AREA - ARCADIA Rod Ejection Accident ARITA - ARTEMIS/RELAP Integrated Transient Analysis CE - Combustion Engineering CHF - Critical Heat Flux CRE - Control Rod Ejection CSLL - Core Safety Limit Lines EM - Evaluation Model FOM - Figure of Merit LOCA - Loss of Coolant Accident LPD LCO - Local Power Density Limiting Condition of Operation Non-LOCA - non-Loss of Coolant Accident NRC - U.S. Nuclear Regulatory Commission PDC - Power Distribution Control PIRT - Phenomena Identification and Ranking Table PWR - Pressurized Water Reactor RLBLOCA - Realistic Large Break LOCA SAFDL - Specified Acceptable Fuel Design Limits SBLOCA - Small Break LOCA SRP - Standard Review Plan
13 ARITA - ARTEMIS/RELAP Integrated Transient Analysis Methodology - Barner and Maupin - ACRS Subcommittee, 6/22/2023 Any reproduction, alteration, transmission to any third party or publication in whole or in part of this document and/or its content is prohibited unless Framatome has provided its prior and written consent.
This document and any information it contains shall not be used for any other purpose than the one for which they were provided. Legal action may be taken against any infringer and/or any person breaching the aforementioned obligations APOLLO-2A, ARCADIA, AREA, ARITA, ARTEMIS, COBRA-FLX, GAIA, GALILEO, M5FRAMATOME and S-RELAP5 are trademarks or registered trademarks of Framatome or its affiliates, in the USA or other countries.
14 ARITA - ARTEMIS/RELAP Integrated Transient Analysis Methodology - Barner and Maupin - ACRS Subcommittee, 6/22/2023
NRC Staffs Review of Framatome Topical Report ANP-10339P, ARITA - ARTEMIS/RELAP Integrated Transient Analysis Methodology Open Presentation to Advisory Committee on Reactor Safeguards, Thermal-Hydraulics Subcommittee June 22, 2023 K. Heller, U.S. NRC J. Lehning, U.S. NRC K. Geelhood, D. Richmond, T. Zipperer, B. Schmitt, D. Engel, PNNL
Presentation Outline Topic
- of Slides Introduction (Open) 3 Review History (Open) 1 Technical Evaluation (Closed) 36
- Scenario Identification / Applicable Regulations
[4]
- Phenomenon Identification and Ranking
[1]
- Evaluation Model Development
[4]
- Calculational Procedure
[8]
- Treatment of Uncertainty
[10]
- Evaluation Model Assessment
[6]
- Supplementary Evaluation Model Features
[3]
Limitations and Conditions (Closed) 17 Conclusions (Open) 1 Presentation Total 58 2
Introduction
- The ARITA methodology is a statistical approach for performing most Standard Review Plan (SRP)
Chapter 15 reactor safety analyses
- Not including LOCA and rod ejection
- Applicable to conventional Westinghouse and Combustion Engineering PWRs
- ARITA involves three distinct evaluation model variants
- The codes used in the ARITA methodology have been previously reviewed by the NRC staff
- NRC staffs review focused mainly on the calculational procedure and uncertainty treatments 3
Key Regulatory Requirements and Guidance
- 10 CFR 50, Appendix A, General Design Criteria, e.g.,
- GDC 10, Reactor Design
- GDC 15, Reactor Coolant System Design
- 10 CFR 50.36, Technical Specifications
- 10 CFR 50.67 or 10 CFR Part 100 Dose Limits
- Standard Review Plan, Chapter 15
- Regulatory Guide 1.203, Evaluation Model Development and Assessment Process 4
Review History FRAMATOME NRC ANP-10339P Submitted Aug 2018 Acceptance Review Complete Nov 2018 Acceptance Review Supplement Mar 2019 Onsite Audit Sept 2019 Batch 1 RAIs (13)
Issued Dec 2019 Prospective L&Cs First Discussed Dec 2020
Response
to 13 RAIs Mar 2020
Response
to 37 RAIs Jul 2020
Response
to 16 RAIs Dec 2020
Response
to 26 RAIs May 2021 Updated Topical Report / Final RAI Response Jun 2022 Batch 2 RAIs (79)
Issued Apr 2020 ACRS SC Jun 2023 Draft SE Apr 2023 2018 2019 2020 2021 2022 2023 19 Audits & Meetings to Resolve RAIs Nov 2020 - April 2022 5
Accptnce Supplmnt Detailed Review RAI Resolution Draft SE
Conclusions
- The NRC staff found the ARITA methodology acceptable for modeling in-scope SRP Chapter 15 events, including
- all three ARITA evaluation model variants
- the associated calculational process
- the statistical uncertainty methodology
- The NRC staff found the supplementary evaluation model features described in Section 3.8 of its safety evaluation acceptable
- The staffs conclusions are predicated upon
- the ARITA methodology being used within its proposed range of applicability in Section 13.0 of ANP-10339P
- licensees acceptably addressing limitations and conditions in Section 5.2 of the staffs safety evaluation 6