ML25153A609
| ML25153A609 | |
| Person / Time | |
|---|---|
| Issue date: | 05/06/2025 |
| From: | Advisory Committee on Reactor Safeguards |
| To: | |
| References | |
| NRC-0336 | |
| Download: ML25153A609 (1) | |
Text
Official Transcript of Proceedings NUCLEAR REGULATORY COMMISSION
Title:
Advisory Committee on Reactor Safeguards Accident Analysis Subcommittee Open Session Docket Number:
(n/a)
Location:
teleconference Date:
Tuesday, May 6, 2025 Work Order No.:
NRC-0336 Pages 1-45 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 ACCIDENT ANALYSIS SUBCOMMITTEE 7
OPEN SESSION 8
+ + + + +
9 TUESDAY 10 MAY 6, 2025 11
+ + + + +
12 The Subcommittee met via Video 13 Teleconference, at 8:30 a.m. EDT, Robert Martin, 14 Chair, presiding.
15 16 SUBCOMMITTEE MEMBERS:
17 ROBERT P. MARTIN, Chair 18 RONALD G. BALLINGER 19 VICKI M. BIER 20 GREGORY H. HALNON 21 CRAIG D. HARRINGTON 22 WALT KIRCHNER 23 SCOTT P. PALMTAG 24 DAVID A. PETTI 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 THOMAS E. ROBERTS 1
MATTHEW W. SUNSERI 2
3 DESIGNATED FEDERAL OFFICIAL:
4 WEIDONG WANG 5
6 ALSO PRESENT:
7 VICTOR CUSUMANO, Deputy Director, DSS 8
ALAN MEGINNIS, Framatome 9
JARON SENECAL, Framatome 10 DAN TINKLER, Framatome 11 PAUL SMITH, Framatome 12 NGOLA OTTO, NRC 13 ASHLEY SMITH, NRC 14 ALEX COLLIER, NRC 15 KEVIN HELLER, NRC 16 LARRY BURKHART, NRC 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 P-R-O-C-E-E-D-I-N-G-S 1
8:30 a.m.
2 CHAIR MARTIN: Good morning. The meeting 3
will now come to order. This is a meeting of the 4
Accident Analysis Subcommittee of the Advisory 5
Committee on Reactor Safeguards.
6 I am Robert Martin, chair of today's 7
subcommittee meeting. ACRS members in attendance in 8
person are Ron, Vicki Bier -- Greg is taking a pass as 9
he gets prepared for another meeting -- we have Craig 10 Harrington, Walt Kirchner, Scott Palmtag, Dave Petti, 11 Tom Roberts, Matt Sunseri, and myself.
12 ACRS members in attendance virtually via 13 Teams -- and I have to check, but I assume, Vesna, 14 you're out there -- Vesna Dimitrijevic, and if I --
15 what's that?
16 MEMBER PETTI: I'm not sure she's on.
17 CHAIR MARTIN: Oh, you're not sure.
18 MEMBER KIRCHNER: And Ron's in transit.
19 CHAIR MARTIN: Okay. If I missed anyone, 20 either ACRS members or consultants, please speak up 21 now. I dont believe we have any consultants today, 22 Weidong Wang, of the ACRS staff is the designated 23 federal officer for this meeting. No member conflicts 24 of interest were identified for today's meeting, 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
4 we have a quorum.
1 During today's meeting, the subcommittee 2
will receive a briefing on Framatome's topical report 3
AMP-10350, Framatome methodology for boiling water 4
- reactors, valuation, and validation of 5
APOLLO2-A/ARTEMIS-B, and the NRC staff's corresponding 6
draft safety evaluation.
7 The ACRS was established by statute and is 8
governed by the Federal Advisory Committee Act, or 9
FACA. The NRC permits FACA in accordance with our 10 regulations.
Per these regulations, and the 11 committee's bylaws, ACRS speaks only through its 12 published letter reports. All member comments should 13 be regarded as only the individual opinion of that 14 member and not a committee position.
15 All relevant information related to ACRS 16 activities, such as letters, rules for meeting 17 participation, and transcripts, are located on the NRC 18 public website and can be found by typing "about us 19 ACRS" in the search field on the NRC's home page.
20 The ACRS, consistent with the agency's 21 value of public transparency in regulation of nuclear 22 facilities, provides opportunity for public comment, 23 and during the proceedings, we have received no 24 written statements or requests to make an oral 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 statement from the public. We have also set aside 1
time at the end of this meeting for public comment.
2 Portions of this meeting may be closed to 3
protect sensitive information, as required by FACA and 4
the government in the Sunshine Act.
5 Attendance during the closed portion of 6
this meeting will be limited to the NRC staff and 7
consultants, the applicant, and those individuals, 8
organizations, that have entered into an appropriate 9
confidential agreement. We will confirm that only 10 eligible individuals are in the closed portion of this 11 meeting.
12 ACRS will gather information, analyze 13 relevant issues and facts, and formulate proposed 14 conclusions and recommendations, as appropriate for 15 deliberation by the full committee.
16 The transcript of the meeting is being 17 kept and will be posted on our website. The 18 participants should first identify themselves and 19 speak with sufficient clarity and volume so that they 20 may be readily heard.
21 If you are not speaking, please mute your 22 computer, mic, Teams, and if you're on Teams, you may 23 need to press Star-6 if you're on the phone.
24 Please do not use the Teams chat feature 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 to conduct sidebar discussions related to the 1
presentations. Rather, limit the use of the meeting 2
chat function to report IT problems.
3 For everyone in the room, please put all 4
your electronic devices in silent mode and mute your 5
laptop microphone and speakers.
6 In
- addition, please keep sidebar 7
discussions in the room to a minimum, since the 8
ceiling microphones, like the one behind me, are live.
9 Presenters, your table microphones are 10 unidirectional and you'll need to speak into the front 11 of the microphone to be heard.
12 Finally, if you have any feedback for ACRS 13 about today's meeting, we encourage you to fill out 14 the public meeting feedback form on the NRC's website.
15 The lead member for this meeting, on 16 Topical Report ANP-10350, is Scott Palmtag, over here 17 to my right. And I would like now to turn the meeting 18 over to him.
19 MR. PALMTAG: Good morning. I'm Scott 20 Palmtag and will lead this morning's discussion.
21 Topical Report ANP-10350P proposes a 22 methodology for the steady state modeling of boiling 23 water reactor cores using the APOLLO2-A/ARTEMIS-B code 24 system.
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 Topical Report describes key aspects of 1
the proposed methodology, its verification validation 2
against experimental data and analytical benchmarks, 3
and derived uncertainties for key core analysis 4
parameters.
5 We are reviewing the topical report 6
because the proposed ANP-10350 key methodology would 7
establish initial conditions for parameters considered 8
in reactor safety analysis, as well as their 9
associated uncertainties.
10 To begin the meeting, I'd like to call on 11 Victor Cusumano, the deputy director of the Division 12 of Safety Systems in NRR, for opening remarks.
13 MR. CUSUMANO: Good morning, thank you.
14 As he said, I'm Vic Cusumano. And we're here to 15 present the staff's evaluation of Framatome's code 16 system to model BWR physics. This is the first of 17 many of expected submittals, Framatome to update the 18 BWR methodology.
19 MR. BURKHART: Vic, excuse me. This is 20 Larry Burkhart. Can you get closer to the mic?
21 MR. CUSUMANO: Bring the mic closer to me.
22 MR. BURKHART: Perfect.
23 MR. CUSUMANO: So, yeah, this the first of 24 many expected submittals to update their methodology.
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 I will note that partway through their 1
review, they submitted a supplement to the topical, to 2
apply to increased enrichment and high burnup.
3 To be more efficient, the supplement is 4
included as part of the topical report review, instead 5
of as a separate review. This was agreed by Framatome 6
and the staff together.
7 I do want to point out the staff and the 8
vendor demonstrated exemplary levels of responsiveness 9
to each other's needs, resulting in an efficient, 10 satisfactory communication, with complex review, with 11 no delays.
12 Thank you for your interest. And as 13 Mr. Palmtag has mentioned, he's from North Carolina.
14 I will not say anything. Not until we talk again.
15 MEMBER PALMTAG: That's good. All right, 16 thank you. And next, we'll turn over to Alan Meginnis 17 for opening statements from Framatome.
18 MR. MEGINNIS: Good morning. I am Alan 19 Meginnis, I am licensing manager for Framatome.
20 I'd like to thank the ACRS for having us 21 here today so that we can tell you about our 22 APOLLO2-A/ARTEMIS-B Topical Report and safety 23 evaluation.
24 APOLLO2-A/ARTEMIS-B is replacing 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 MICROBURN-B2/CASMO4 at the core simulator in our 1
advanced analysis methods for boiling water reactors.
2 Previously, APOLLO2-A and ARTEMIS have 3
been approved for use with the PWR reactor. And this 4
topical report is extending this applicability for 5
boiling water reactor.
6 This is the last upgrade of our advanced 7
methods that Framatome is going to make for boiling 8
water reactor, prior to our efforts to go to increased 9
enrichment and increased burnup. Framatome calls that 10 effort advanced fuel management, AFM.
11 So, in fact, this supplement, or this 12 topical report, had supplemental information that was 13 submitted, as Vic pointed out, to support AFM during 14 the course of the topical report review.
15 So, this topical report is also the first 16 of Framatome's boiling water reactor methodologies 17 that is going to implement AFM before we submit the 18 additional topical reports going forward.
19 Framatome appreciates the NRC's efforts in 20 reviewing this topical report and we especially 21 appreciate the flexibility they had in allowing us to 22 submit the AFM supplement in the process of the 23 topical report in order to accelerate our 24 implementation of AFM. It probably shaved a year off 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 of our implementation schedule, allowing us to do 1
that, so we very much appreciate it.
2 Of course, we're anxious to get this 3
topical report approved so that we can move forward 4
with our AFM implementation to support industry needs.
5 Thank you.
6 MEMBER PALMTAG: Thank you, Alan. I just 7
had a quick question before we started. It sounds 8
like this is going to be the first time that PWR and 9
BWR methods are going to be combined for Framatome.
10 Is that correct? Before, we had different codes for 11 P's and B's?
12 MR. MEGINNIS: All right. So, the base 13 methodology is going to be the same codes for the core 14 simulator. But we have extensions that are only 15 applicable for boiling water reactor in this topical 16 report.
17 MEMBER PALMTAG: So, APOLLO2 will be used 18 for both PWRs and BWRs?
19 MR. MEGINNIS: That is correct.
20 MEMBER PALMTAG: And ARTEMIS-B, is that a 21 different code than the PWR one?
22 MR. MEGINNIS: That is the code -- it has 23 extensions in it for boiling water reactor 24 application. That's the B.
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 MEMBER PALMTAG: Okay, thank you. I think 1
that's an important point.
2 CHAIR MARTIN: Since you're talking 3
code -- I know we're jumping the gun a little bit on 4
some of the slides, this is Bob Martin, so is there 5
like an input parameter in the code that just says, 6
this is for BEM, or something like a BWREM, and then 7
it of course pulls into the solution? It follows 8
correlations that are applicable, so in some ways it's 9
kind of a merge code, rather than the same code?
10 MR. MEGINNIS: I'm going to have to refer 11 that to Jaron.
12 MR.
SENECAL:
There'd be separate 13 executables.
14 CHAIR MARTIN: Okay. So, the way you 15 manage it, ARTEMIS-B is just its own standalone, while 16 it has some foundational similarities with what we've 17 seen before -- because I believe we looked at this 18 about a years ago?
19 MR. SENECAL: A year or more.
20 CHAIR MARTIN: They share the same name.
21 But as far as code management internally, they are 22 separate codes.
23 MR. SENECAL: Yes, how we do leverage it, 24 all our lessons learned across the organization, 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
12 vast majority of the coding is distinct.
1 CHAIR MARTIN: Sure. Okay. So, can I 2
introduce our speakers?
3 MEMBER PALMTAG: Yes, please. Sorry to 4
jump the gun.
5 MR. MEGINNIS: Okay. So, first we have on 6
the left over here, far left, is Jaron Senecal. Jaron 7
is the APOLLO2-A/ARTEMIS-B lead developer. Jaron 8
earned a bachelor's of science from Walla Walla 9
University, and went on to earn a doctorate in nuclear 10 science and engineering from Rensselaer Polytechnic 11 Institute.
12 Okay, Paul Smith is directly to my left.
13 Paul is the Framatome's BWR neutronics codes and 14 methods team leader. He has a master's of science in 15 nuclear engineering from the University of New Mexico, 16 and is a licensed professional engineer in the State 17 of Washington. Thank you.
18 MR. SENECAL: All right, lets get 19 started. Is this volume okay?
20 MEMBER KIRCHNER: Just pull it up to you.
21 MR. SENECAL: Is that better? Okay. All 22 right. So, we'll give an overview of the topical 23 report in this open session and we'll leave some of 24 the further details to the closed session.
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13 For the next slide, we just have a brief 1
overview of what we'll talk about. We'll go through 2
the computer codes, and then describe the methods and 3
models, and then list the various verification and 4
validation efforts that are included in the topical 5
report. Next slide.
6 Starting with computer codes, just to give 7
a little background -- you can go to the next slide.
8 Thanks.
9 Alan kind of touched on this already, but 10 we're kind of inheriting, you could say, from two 11 different approved methodologies.
12 On the BWR
- side, there was 13 CASMO4/MICROBURN-B2, and we're inheriting some models 14 from that -- I'll discuss that further -- and on the 15 PWR
- side, the approved topical report is 16 APOLLO2-A/ARTEMIS. And so, that's, as we mentioned, 17 the backbone of the codes that we're building off of.
18 And so, in this topical report we're 19 discussing APOLLO2-A/ARTEMIS-B, and this is the first 20 in a series of topical reports for the next generation 21 of codes/methods for BWRs. This topical report is 22 applicable to steady state calculations, and it 23 includes the supplement regarding increased enrichment 24 and burnup. Next slide.
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14 So, the APOLLO2-A code is a lattice 1
physics code. It calculates the figure of cross-2 sections for the ARTEMIS-B core simulator. It solves 3
the 2D neutron transport equation using a three-level 4
computational scheme, it uses the SHEM281 energy group 5
mesh for neutrons, and for gammas it uses 94 energy 6
groups.
7 All of the physical data comes from the 8
JEFF 3.1.1 cross-section library, with modifications 9
that are described in the approved PWR topical report 10 supplement.
11 As far as APOLLO2-A, the lattice physics 12 code, it does not include any additional models 13 specifically, for boiling water reactors. Go to the 14 next slide.
15 In the middle, we have this HERMES-B code.
16 It takes the cross-section data directly from the 17 APOLLO2-A code and creates a multi-dimensional 18 functional representation of the cross-sections.
19 And then this representation can be 20 interpolated at arbitrary conditions for use in 21 ARTEMIS.
22 So, the data that HERMES functionalizes 23 for ARTEMIS includes microscopic cross-sections, as 24 well as the macroscopic cross-sections for, like, all 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 those residual cross-sections, for all the isotopes 1
that are less-important, and the delta cross-section 2
model for the control blade insertion.
3 It also includes the pin form factors, 4
discontinuity factors, detector responses, and key 5
deposition fractions.
6 Next, we'll go to ARTEMIS-B. It's the 7
extension of ARTEMIS. So, the PWR code, we added on 8
to it to be applicable to boiling water reactors. He 9
uses much of the same methodology that's described in 10 the ARCADIA Topical 10-297, and it contains the 11 following modules: Flex Module, Fuel Rod, and thermal 12 hydraulics modules, the dehomogenization modules --
13 think of that as pin power reconstruction -- and the 14 depletion module. Go to the next slide.
15 CHAIR MARTIN: Point of clarification.
16 The methodology overall, just looking at steady state 17 transient accident conditions?
18 MR. SENECAL: Sure. Yeah, the scope of 19 this topical report. So, well go to methods and 20 models, give an overview of that.
21 MEMBER PALMTAG: So, Bob, this is going to 22 be steady states. But I assume this is going to feed 23 the transient analysis in later topical reports.
24 MR. SENECAL: Yeah. Like he said, it was 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 just the initial conditions.
1 MEMBER PALMTAG: So, it's not directly 2
kinetics now, but it's going to be very important for 3
intra-kinetic.
4 While I'm talking, I just want to make a 5
comment. But the APOLLO code's been around for quite 6
a while and has, just from my impression, has a very 7
good reputation, I would assume to be very similar 8
results.
9 This MOC can be very similar results 10 between the APOLLO2 and your previous CASMO4. That 11 shouldn't be any surprises to the committee.
12 It is interesting that you picked the 13 JEFF 3.1 library, just for pretty much familiar with 14 most -- or I'd say, as far as I know, everyone in the 15 U.S. is using the ENDF/B-VII data libraries, or maybe 16 earlier.
17 So, this is going to be the first time 18 that the JEFF 3.1.1 library's going to be used, which 19 should be very similar, but it's a European library, 20 as opposed to ENDF libraries, is the U.S. library.
21 But just kind of jumping ahead of your validation, 22 which tells us whether it's good or not. But it is 23 kind of interesting as to the JEFF library instead of 24 the ENDF library.
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17 MR. SENECAL: Yeah, the APOLLO code is 1
generally maintained in France. So, that's our French 2
connection in our company. So, we'll start with the 3
similarities to the ARCADIA Topical Report. In the 4
ARTEMIS
- code, there's three modules that are 5
essentially unchanged.
6 Flux solver, it uses the same semi-7 analytical nodal expansion method with coarse mesh 8
rebalancing, the dehomogenization module calculates 9
inter-nodal quantities, like pin powers and burnups, 10 and the depletion module, which uses a Krylov subspace 11 method for solving the depletion equations. Go to the 12 next slide.
13 The Fuel Rod Module, it's solving the 1D 14 Heat Transfer equation. It's presented here in radial 15 coordinates. It's solved on a representative fuel rod 16 in a lattice, and that calculates the effective fuel 17 temperature for Doppler feedback.
18 Comparing it back to the PWR Topical 19 Report, this is the same numerical solution method.
20 We only changed the method behind it. But the 21 properties have been updated to be consistent with the 22 approved RODEX4 topical report, which we use for BWR 23 thermal mechanic analysis.
24 So, these properties include the pellet 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 radial power distribution, the thermal conductivity, 1
gap conductance and porosity tables. Next slide.
2 CHAIR MARTIN: Just another point of 3
clarification. You say 1D, but you have axial nodes, 4
or whatever you want to call them, and of course all 5
individually drive the 1D. So, it's a pseudo-2D, in 6
essence, right? There's just no axial conduction.
7 MR. SENECAL: Yeah, there's no axial 8
component to it.
9 Then the thermal-hydraulic module is 10 another change for the PWRs. It solves the fluid 11 conditions in the core and gives feedback to the Flex 12 Module in the boiling water reactors, with the fuel 13 channels.
14 You basically have a system of parallel 15 flow paths, the main one being the active coolant 16 around the fuel rods inside the channel box, but 17 there's also parallel flow paths for bypass and 18 internal water channels, and all those are connected 19 at the bottom and the top, so they experience the same 20 pressure drops.
21 The ARTEMIS-B thermal-hydraulics module is 22 very similar to the MICROBURN-B2 approved methodology.
23 Next slide.
24 We'll discuss these more in the closed 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 session, but there's a variety of PWR-specific models 1
that were implemented into ARTEMIS-B: variable axial 2
nodalization module, we call that VAx, spacer grid and 3
detector models, control blade depletion and control 4
blade history models, the reflector models specific to 5
BWRs, and we'll also discuss the jumpstart model.
6 CHAIR MARTIN: Real quick, probably on the 7
previous slide I believe, to the thermal-hydraulics, 8
so how do you model, say, non-uniform flows, with BWR 9
core, I mean, the kind of radial subdivision of the 10 core? It's bundle-by-bundle, or rings, or -- how do 11 you deal with that inherent non-uniformity of flow 12 through a core?
13 MR. SENECAL: Do you mean, like, different 14 pressure drops between different assemblies?
15 CHAIR MARTIN: All of it. It's the core-16 wide, not just the bundle.
17 MR. SENECAL: So, each assembly is solved 18 independent. We're not lumping assemblies together.
19 So, each one is a flow path that's modeled 20 exclusively.
21 CHAIR MARTIN: Okay. And then -- well 22 obviously there's a bundle, so they're not cross-23 communicating. Okay. So then what feeds that initial 24 condition of the flows through? Where does 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
20 information come from?
1 MR. SENECAL: Usually, it's plant data, 2
where you have the re-circulation pump flow.
3 CHAIR MARTIN: Okay.
4 MR. SENECAL: Inlet flow. And so, along 5
with pressure and inlet subcooling.
6 CHAIR MARTIN: Well, you look at it all 7
kind of separately then. Regions. That would have to 8
feed into your downstream codes.
9 MR. SENECAL: Each bundle's solved 10 separately, but they're all uncoupled at the top and 11 the bottom --
12 CHAIR MARTIN: Sure.
13 MR. SENECAL: -- so they ensure the 14 crosstalk in that way.
15 CHAIR MARTIN: Okay.
16 MR. SENECAL: Does that answer your 17 question?
18 CHAIR MARTIN: It does.
19 MR. SENECAL: So, go onto the next slide.
20 So now, given overview of the verification and 21 validation efforts that we did, for APOLLO2-A we had 22 three different types of experiments or data that we 23 compared against.
24 First is critical experiments. These all 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 include reactivity, but some of them also include 1
fission rate distributions. We have a variety of 2
experiments that we included.
3 Listing them
- here, there's
- BASALA, 4
EPICURE, Babcock & Wilcox, CAMELEON, and the ICSBEP.
5 So, from each of those we have a select number of 6
experiments that we include.
7 The next type of data is from spent fuel 8
isotopic measurements. We have measurements from the 9
Fukushima Daini, units 1 and 2, boiling water 10 reactors, and we also included fuel pins from the 11 REGAL experiments, which is a pressurized water 12 reactor, but we included it because it has ten percent 13 gadolinium in at least one of the fuel pins, and that 14 was representative of boiling water reactors, in terms 15 of gadolinium, so we included that as well.
16 And then finally, to fill in all the gaps 17 between experimental data, we have Monte Carlo 18 comparisons, which can be used to span arbitrary 19 conditions and configurations. So, a wide variety of 20 those, using them to validate reactivity, pin powers, 21 burnup, and gamma transport as well.
22 CHAIR MARTIN: Just kind of a standard 23 question for any of the V&V, particularly for an 24 applicant like you all have been around a long time.
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22 Just making the V&V program that you had 1
for the prior methodology, and then reapplied it for 2
the most part. So, are there new cases added? Were 3
there some old cases removed? It's just a 4
continuation of the same script. Applying it, of 5
course, would make new models for all those old cases 6
that you've used in prior methodology.
7 MR. SENECAL: So, the cases are all 8
selected to represent boiling water reactors as much 9
as possible. So, we're looking for things that have 10 void, or simulated void, like the spent fuel. We 11 selected as many boiling water reactors as possible.
12 So, everything in the topical report is tailored to --
13 CHAIR MARTIN: That doesn't quite answer 14 the question. So, youve been working with BWRs a 15 long time, you have the prior methodology based on, 16 say, microburn. Those, of course, had been V&Ved.
17 My question really was, have you just 18 really taken the old V&V package for that methodology, 19 and then converted into models and such to do your V&V 20 for the APOLLO/ARTEMIS-B combination?
21 MR. SENECAL: I believe most of the 22 validations run separate experiments. So, it's not 23 primarily just translating, but it's more --
24 CHAIR MARTIN: So, the answer would have 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 been, if you said, yeah, a hundred percent, obviously 1
there's an institutional memory here with -- well, 2
agency-wide, with, of course, your methodologies in 3
the past.
4 So, there were some additions, 5
subtractions, from the old methodology V&V into this 6
one. Okay. Well, that's important.
7 I guess youre still looking at, like, 8
fifty or so different benchmarks. I mean, you've 9
still got a significant package here. But there are 10 some differences from the old methodologies.
11 MR. SENECAL: Yeah, and the CASMO 12 microburn is twenty-six years old now. So, we're 13 trying to use as many recent fuel types as possible.
14 CHAIR MARTIN: All right. Good point to 15 know.
16 MR. SENECAL: For the ARTEMIS verification 17 and validation for the next slide -- so we do 18 verification of the Fuel Rod Module by comparing it 19 against the RODEX4 results to show that the material 20 properties have been implemented correctly.
21 We compared the reflector model using 22 numerical validation against the SERPENT2 Monte Carlo 23 code.
24 Next, we did the verification of 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
24 ARTEMIS-B Pin Powers, using colorset calculations that 1
are compared against APOLLO2-A.
2 And then for the Thermal-Hydraulics 3
Module, we had validation for pressure drop and 4
channel average void fraction data.
5 For more integral experiments, we have 6
Core Follow data from 110 cycles from 8 different 7
reactors. And additionally, we have Pin and Nodal 8
Gamma Scan Results from three reactors, over five 9
different cycles. Move to the next slide.
10 And then finally, we mentioned there's --
11 well, it's already been mentioned that there's a 12 supplement regarding advanced fuel management, or AFM.
13 We use this to signify increased enrichment Uranium 14 235 and increase in their maximum full length fuel rod 15 average burnup limit.
16 We extended the verification and 17 validation to this new regime by adding additional 18 critical experiments, and in APOLLO2-A we also did 19 additional numerical validation against SERPENT, and 20 then we also, in ARTEMIS, did extensive verification 21 of the pin powers against the fall. Next slide.
22 CHAIR MARTIN: This may be a time to ask 23 about higher burnups. Obviously, there's a move 24 industry-wide, looking at, so your new V&V starts 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 looking at validation sets for higher burnups.
1 Maybe where did you get that data from?
2 What's the background there?
3 MR. SENECAL: So, the first thing is we 4
can -- again, SERPENT for the numerical validation, we 5
can just simply run it out to higher burnups.
6 Some of the other verifications, same 7
story against RODEX4 in the FRM, for example.
8 CHAIR MARTIN: You're kind of talking 9
about code-to-code comparisons there?
10 MR. SENECAL: Yes.
11 CHAIR MARTIN: Right. I'd find more 12 valuable from a verification standpoint, given certain 13 amount of history, and what the prior organizations or 14 personnel have done with those codes, talking about 15 validation, when we're talking higher burnup.
16 MR. SMITH: Hi, this is Paul. So, I think 17 to answer your question, a lot of what the validation 18 is for this topical report would be code-to-code 19 comparisons, as the data that maybe you're speaking of 20 would be more applicable to, like, the RODEX4 21 supplement, where they're looking at physical 22 phenomena, like issue gas, things like that.
23 The main important piece for ARTEMIS is 24 the fuel temperature calculation. And so, we want 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
26 show that our fuel temperature calculation faithfully 1
reproduces the RODEX4 temperature calculation, for 2
instance.
3 So, that would be one aspect of how we 4
extend burnup and show that we're okay in terms of our 5
overall methodology. Does that make sense?
6 CHAIR MARTIN: Certainly it does. It 7
makes it more difficult to quantify uncertainties if 8
you're looking out there. And then, of course, it 9
just puts the burden on how you handle uncertainties.
10 So, I guess we're split here about that too. Right.
11 MEMBER PALMTAG: Can you go back one 12 slide?
13 MR. SENECAL: Sure.
14 MEMBER PALMTAG: This is Scott Palmtag.
15 To be more specific, when you did the higher burnups 16 on isotopic. You're just comparing to SERPENT. But 17 in the last slide, I can tell you there's something 18 wrong with the library in terms of fission product.
19 Are there any critical experiments that go to higher 20 burnups/isotopics comparisons?
21 MR. SENECAL: Most critical experiments 22 are going to be clean fuel.
23 MEMBER PALMTAG: Are there any isotopic 24 measurements at higher exposures?
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27 MR. SENECAL: I don't recall the burnup 1
levels --
2 MEMBER PALMTAG: You've got a couple of 3
BWRs in a previous slide -- Fukushima -- and then do 4
you know what those burnups were?
5 MR. SENECAL: That would be included in 6
the topical report.
7 MEMBER PALMTAG: Okay. I don't believe 8
they're higher, over 62.
9 MR. SMITH: That's right. There's really 10 a limited amount of data, in terms of what's actually 11 out there.
12 So, again, when we talk to the NRC about 13 this, they've asked questions in the RAIs and we were 14 able to give them some additional code-to-code 15 comparisons that they asked for, to deal with the 16 isotopics.
17 MEMBER PALMTAG: Right. And you're not 18 the only vendor who's got to deal with this as we go 19 to the higher exposure.
20 Do you think there's a need for more 21 experimental data to get the isotopics from higher?
22 Or do you know of any planned experiments to get the 23 higher isotopics for higher burnup?
24 MR. SENECAL: I'm not aware of any. But 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 it is something in terms of it could use improvement 1
when that data comes in.
2 I think the goal, industry-wide, would be 3
to get that data when it comes in, and ensure that we 4
model things correctly. So, continuous validation as 5
we go.
6 MEMBER PALMTAG: Okay, thank you.
7 MR. SENECAL: Are there further questions?
8 We can wrap up with the conclusion.
9 Basically, we introduced the 10 APOLLO2-A/ARTEMIS-B code system, given full review of 11 the main code modules and models, and brief 12 description of the verification and validation that's 13 included in the topical report. Next slide.
14 CHAIR MARTIN: Okay, are there further 15 questions for Framatome? Any of the members?
16 MEMBER PALMTAG: I should note, there'll 17 be more questions in the closed session.
18 CHAIR MARTIN: Of course, there will be a 19 closed session. I guess at this point we'll 20 transition to the staff. So, we'll pause for a 21 moment.
22 (Pause.)
23 CHAIR MARTIN: Feel free to take off here.
24 MR. OTTO: Good morning. I'm Ngola Otto, 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 I'm the project manager of Framatome Topical Reports 1
and I would just like to start off by saying thank you 2
for the ACRS Subcommittee for giving us the 3
opportunity to present on the review of the 4
Framatome's ANP-10350P, revision zero, Topical Report.
5 And the review team includes Ashley Smith, 6
who's here, Alex Collier, and also we do have other 7
review team members, Jack --
8 (Audio interference.)
9 MR. OTTO: -- at the back, and also Kevin 10 Heller, who's supporting us remotely. And we do have 11 other staff members here who are available to support 12 today's meeting.
13 And so, as mentioned previously, we were 14 able to conduct this review in an efficient manner by 15 incorporating both the original submittal, plus the 16 increased enrichment and higher burnup supplemental 17 information, and we saved probably a one-year review 18 time by doing that.
19 And so, we did issue four sets of RAIs and 20 we did conduct two regular audits, and we held a 21 number of public meetings to ask questions and get 22 things resolved regarding review.
23 So, during this
- session, we'll be 24 discussing our findings, and we'll probably get into 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 more detail in the closed session that follows. So, 1
with that, I'll turn it over to the staff to start the 2
presentation.
3 MS. SMITH: Thanks, Ngola. Can you hear 4
me? Should I move closer? That better?
5 As noted, I'm Ashley Smith from the Office 6
of Nuclear Reactor Regulation, Division of Safety 7
Systems, representing the Nuclear Methods and Fuel 8
Analysis Branch. Here with me is Alex Collier, and 9
we'll be presenting the staff review of ANP-10350P, 10 the methodology for boiling water reactors, valuation 11 and validation of APOLLO2-A/ARTEMIS-B. Next slide.
12 There's an agenda for the staff 13 presentation in the open session, presenting some 14 areas we thought would be of interest to you.
15 We'll give a brief introduction, talk a 16 bit about our review timeline, discuss the regulatory 17 requirements and guidance, areas of the technical 18 evaluation, the supplement for increased enrichment 19 and high burnup, staff limitations and conditions, and 20 give a conclusion. Next slide.
21 Framatome's gone over this information, so 22 I'm going to skim through it. Framatome proposed the 23 APOLLO2-A/ARTEMIS-B code system to model core physics 24 in BWRs.
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31 This topical report describes the 1
methodology and verification and validation applicable 2
to steady state BWR core modeling.
3 As mentioned by Framatome, this is one of 4
multiple reports expected to update their BWR 5
methodology. Next slide.
6 APOLLO2-A/ARTEMIS-B is an extension of the 7
ARCADIA code system to BWRs. It includes the 8
APOLLO2-A spectral code, ARTEMIS-B core simulator, and 9
the cross-section functionalization code HERMES-B.
10 ARTEMIS and HERMES codes were extended by 11 adding BWR-specific models adapted from the 12 MICROBURN-B2 BWR core simulator. As a note, APOLLO2-A 13 was not modified. The flow chart here shows how these 14 codes are incorporated. Next slide.
15 This is a
review timeline of key 16 activities throughout the review. The orange diamonds 17 on the top of the timeline represent Framatome 18 activities, and the green circles on the bottom 19 represent NRC activities.
20 We've already mentioned a few other times, 21 that about a year into the review, Framatome submitted 22 a supplement to the topical report, to include 23 increased enrichment and high burnup.
24 This path was agreed upon by NRC 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
32 Framatome, prior to submitting the supplement, to 1
increase the overall efficiency in the review process 2
and support increased enrichment and high burnup 3
industry initiatives.
4 Theres also staff turnover during this 5
time, so I want to mention that up front, that the 6
lead reviewer left our branch midway through the 7
review and is no longer with the agency. So, in some 8
cases we may be relying on others to answer questions.
9 Next slide.
10 NUREG-0800, also known as the Standard 11 Review Plan, provides guidance for the NRC staff in 12 reviewing safety analysis reports for nuclear power 13 plants. Chapter 4.3 of this document focuses on the 14 nuclear design aspects of a reactor core.
15 Primary objectives of this section are to 16 ensure that fuel design limits are not exceeded during 17 normal operations, or anticipated operational 18 transients. Postulated reactivity accidents do not 19 compromise the reactor coolant pressure boundary, and 20 core coolability is maintained. Next slide.
21 Acceptance criteria outlined in SRP 4.3 22 are based on compliance with relevant general design 23 criteria. Particularly, the GDCs that are listed 24 here.
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33 These criteria focus on ensuring Reactor 1
Design safety, control of reactivity, and maintenance 2
of core cooling activity. Next slide.
3 The NRC staff reviews the areas concerning 4
analytical methods. These are: the descriptions of 5
the analytical methods used in the nuclear design, 6
including those for predicting criticality, reactivity 7
coefficients, burnup, and stability; the database used 8
for neutron cross-section data and other nuclear 9
parameters; and the verification of analytical methods 10 for comparison with measured data.
11 There are no specific criteria that must 12 be met by analytical methods or data used by a vendor.
13 In general, the analytical methods and 14 database should be representative of state-of-the-art 15 and the experiments used to validate the analytical 16 method should be adequate of fuel designs in the 17 reactor, and encompass a sufficient range of variables 18 and operating conditions.
19 I'm going to turn it over to Alex to 20 discuss the neutronics.
21 MS. COLLIER: Thank you, Ashley. I'm Alex 22 Collier, technical reviewer at the Nuclear Methods and 23 Fuel Analysis Branch.
24 Framatome has already stated that no 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 changes were made to APOLLO2-A for its application to 1
boiling water reactors.
2 Given the capabilities of the method and 3
the validation that has been discussed previously by 4
Framatome, and will be discussed further in future 5
slides, the NRC staff finds APOLLO2-A acceptable for 6
BWR applications.
7 Given that BWRs operate under different 8
thermal-hydraulic conditions than PWRs, which is its 9
original purpose, the NRC staff focused on how 10 HERMES-B functionalized cross-sections.
11 The NRC staff asked an RAI and Framatome 12 provided, a sensitivity steady using core-follow 13 benchmarks from reactors operating under modern 14 conditions with modern fuels.
15 Sensitivity studies showed that HERMES 16 appropriately functionalizes cross-sections for 17 downstream calculations. Next slide, please.
18 A lot of models for ARTEMIS-B were adapted 19 from MICROBURN-B2, which has been previously reviewed 20 and approved by the NRC staff. The sensitivity steady 21 and the RAI that was mentioned in the previous slide 22 supports the cross-section parameterization model in 23 ARTEMIS.
24 The NRC staff reviewed the models 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
35 Framatome has discussed previously, and have found 1
them acceptable for boiling water reactor 2
applications.
3 Ashley is going to be speaking next on the 4
thermal-hydraulic and fuel rod module methodologies.
5 Next slide, please.
6 MS. SMITH: Framatome's already discussed 7
the thermal-hydraulic methodology in detail. So, to 8
recap, the thermal-hydraulic methodology used by 9
ARTEMIS-B is similar to the MICROBURN-B2 core 10 simulator.
11 Minor improvements were made for ARTEMIS-B 12 and the ARTEMIS-B thermal-hydraulic module used an 13 iterative calculation scheme, which was shown by 14 Framatome.
15 Staff found that the thermal-hydraulic 16 methods were acceptable because they're consistent 17 with approved methodologies, such as MICROBURN-B2.
18 Next slide.
19 Again, Framatome's already discussed the 20 information on this slide in detail. I'll recap that 21 the ARTEMIS-B fuel rod module is comparable to the 22 ARTEMIS fuel rod module approved by NRC staff.
23 The numerical solution of the heat 24 transfer equation is the same as the method used 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
36 ARTEMIS.
1 Physical properties in ARTEMIS-B are 2
updated from ARTEMIS to be consistent with RODEX4, 3
which is also approved by NRC staff.
4 Effective fuel temperature is the main 5
output for the fuel rod module.
6 NRC staff determined the effective fuel 7
temperature equation used in ARTEMIS-B is consistent 8
with MICROBURN-B2.
9 The staff concluded that the fuel rod 10 module methodology is acceptable, because it's 11 consistent with industry standard codes that are 12 approved by the NRC.
13 Alex will discuss validation and 14 verification.
15 MS. COLLIER: Thank you. The NRC staff 16 reviewed the validation and verification presented by 17 Framatome. Staff focused on the databases that 18 Framatome used and the methods covering the entire 19 range of applicability, and the results that Framatome 20 found and any present trends or biases.
21 The NRC staff found that the validation 22 adequately assessed every area that the code is 23 anticipated to assess, and found the predictive 24 capability of the system acceptable. Next slide, 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 please.
1 MEMBER PALMTAG: This is Scott Palmtag.
2 MS. COLLIER: Yes.
3 MEMBER PALMTAG: So, we asked this 4
question earlier of Framatome. But really its a 5
broader question for the industry. But as we go to 6
these higher burnups, do you think there's experiments 7
needed for isotopic measurements at high burnups?
8 MS. SMITH: I mean, whether or not it's 9
needed -- we can speak about it more in the closed 10 session, but I am aware of some spent fuel 11 measurements that did go beyond the current limit, and 12 the extension with numerical methods with a higher org 13 code do kind of solidify the idea that the code is 14 performing well.
15 MEMBER PALMTAG: The codes all use a 16 common library. So, it's not going to tell you if 17 you're missing something in the library. You 18 mentioned we can talk about it further.
19 I wouldn't be surprised if the NRC does 20 see a need for that, the more experimental data for 21 isotopics at higher burnups.
22 MS. SMITH: Okay.
23 MEMBER PETTI: I've got a question.
24 MS. SMITH: Yes.
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38 MEMBER PETTI: On the last slide.
1 Previous slide. The last bullet, it's not a 2
verification, it's a validation. But you say 3
verification.
4 MS. SMITH: It's mostly validation.
5 MEMBER PETTI: Validation.
6 MS. SMITH: It's mostly validation.
7 MEMBER PETTI: It's data. Yes. Okay, 8
thank you.
9 CHAIR MARTIN: I mean, we oftentimes get 10 confused with the different words here. Verification, 11 I look at anything that's the code comparison, because 12 there's not validation. That's their verification, 13 particularly when the codes that they're benchmarking 14 against have been V&Ved before.
15 So, it's something that I would think --
16 on this list you have validation, but you also have, 17 as Framatome said earlier, code-to-code comparisons 18 that probably fall in the category of verification.
19 MEMBER PETTI: Right.
20 CHAIR MARTIN: And among the sets and 21 under the category of V&V, is mostly -- is there good 22 balance between say, what we'd call verification and 23 validation?
24 We all would love to see more and more 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 validation -- you know, seeing-is-believing kind of 1
thing. But what is your opinion, or assessment, of 2
the balance of the code test cases that they selected 3
and used?
4 MS. SMITH: I'm aware that Framatome did 5
call the verification numerical validation, and I do 6
kind of see it in that sense. It's comparing to a 7
higher order of magnitude than SERPENT. It's a Monte 8
Carlo code, which we all know is pretty solid.
9 They use a massive range of cases to 10 extend kind of the range of applicability. And they 11 went beyond what they were asking for. And they kept 12 track of all the trends and took note of why there 13 were any trends or any biases that were there.
14 So, we can talk about it more in the 15 closed session, to get into details. But it's the 16 staff's conclusion that it's adequate.
17 CHAIR MARTIN: Yeah. I do find it 18 interesting -- and again as more maybe -- I have to 19 defer to my colleagues that have more reactor physics 20 experience -- but we do see more and more deference to 21
- SERPENT, where I
don't believe it has been 22 incorporated into any evaluation model for domestic 23 applications.
24 And my experts not just here at the table, 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
40 but that I have worked with in the past, there is this 1
broad community acceptance for SERPENT, but it hasn't 2
gone through that kind of vetting in the agency.
3 Should it? I don't know. I look at Scott too. I 4
mean, you ever have these kind of questions?
5 MEMBER PALMTAG: No, I agree. I think 6
people at the top, Monte Carlo, and it used to be 7
MCNP, everybody just used to trust MCNP. But I do 8
want to note that the Monte Carlo that MCNP and 9
SERPENT and Open MCs, have higher order of neutronic 10 methods, but their depletions not really a higher 11 order, its the same depletion matrix that everyone 12 else is solving, has more isotopes. But I wouldn't 13 really necessarily call the depletion part of SERPENT, 14 a higher order method, than any other methods.
15 MS. COLLIER: I am aware that SERPENT uses 16 the CRAM methodology for depletion, which --
17 MEMBER PALMTAG: Which is the exponential 18 matrix you're solving, so there's nothing --
19 MS. COLLIER: Yeah.
20 MEMBER PALMTAG: -- it's not a higher 21 order method than anyone else is using. They do use 22 a lot more isotopes. That there's a problem in the 23 library that's going to show up in all the codes. All 24 the codes are going to have the same library.
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41 MS. COLLIER: That's true. To note on the 1
CRAM method, it is very robust and it's --
2 MEMBER PALMTAG: It's a numerical method, 3
right?
4 MS. COLLIER: It is.
5 MEMBER PALMTAG: It's not going to tell 6
you anything about whether the data's right or wrong.
7 MS. COLLIER: Correct. As mentioned in 8
the timeline, Framatome submitted a supplement to the 9
topical report to extend the range of applicability to 10 include increased enrichment and higher burnup 11 conditions.
12 Framatome has stated that they refer to 13 this as advanced fuel management conditions. The 14 supplement contains additional verification and 15 validation to demonstrate the accuracy of the 16 APOLLO2-A/ARTEMIS-B code system for these extended 17 conditions.
18 The NRC staff concluded that the code 19 system is acceptable for use at AFM conditions.
20 Detailed discussion of the supplement will be in the 21 closed session. Next slide, please.
22 There are three limitations and conditions 23 in the staff's safety evaluation. First, the 24 ARTEMIS-B methodology is applicable to steady state 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
42 conditions associated with all reactor modes.
1
- Second, the APOLLO2-A/ARTEMIS-B code 2
system is limited to analyzing BWR fuel assemblies 3
with square lattices and fuel designs validated within 4
the topical report, such as ATRIUM-10 and ATRIUM-11 5
fuels.
6 However, this methodology may be validated 7
for use with other fuel, based on the similarity to 8
existing fuel product lines validated within the 9
topical report.
10 Third, the ARTEMIS-B fuel rod module 11 within APOLLO2-A/ARTEMIS-B is subject to relevant 12 limitations and conditions contained with the current 13 RODEX4 topical report and safety evaluation, which 14 means burnup limitations for APOLLO2-A/ARTEMIS-B are 15 based on the non-AFM limitations. As well discuss 16 further in the closed session. Next slide, please.
17 The NRC staff found the code system 18 acceptable for application to steady and time design 19 analysis of boiling water reactors.
Staffs 20 conclusions are predicated upon licensees acceptably 21 addressing the limitations and conditions in Section 4 22 of the NRC SE. Are there any additional questions?
23 CHAIR MARTIN: That's my line. Are there 24 any additional questions from the members? Okay.
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43 MEMBER PALMTAG: This is Scott Palmtag.
1 I have one more question.
2 Going back to APOLLO2, you said there was 3
no differences between -- there should, I asked 4
Framatome -- but there's no differences between the 5
previous submittal. Did the previous submittal 6
actually have PWR geometry, or did -- I mean, they 7
said there was no changes though. Is it to the 8
methodologies, or to the geometry?
9 MS. COLLIER: I think it would be best if 10 Framatome answered this question.
11 MEMBER PALMTAG: Someone from Framatome?
12 When you said there was no changes to the APOLLO2, did 13 you mean in geometry, or just the methodology? You 14 can stand up right behind Bob, where that green line 15 is. Yeah.
16 CHAIR MARTIN: Can you say your name?
17 MR.
SENECAL:
Jaron Senecal with 18 Framatome. Could you repeat that question, please?
19 MEMBER PALMTAG: When you said that there 20 was no changes to the APOLLO2 compared to the previous 21 submittal, did the previous submittal have the PWR 22 geometry in it, or are you referring just to the 23 methodology --
24 MR.
SENECAL:
So, that's not a
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44 methodological change. There's things like higher 1
void and certain outputs that are necessary --
2 MEMBER PALMTAG: The channel -- this would 3
be like the channel box to the BWR geometries. Was 4
that included in the previous submittal?
5 MR. SENECAL: It would not have been 6
presented in the previous submittal. I do not 7
remember the version of the code in which these 8
features came out and how that relates to the specific 9
timeline.
10 MEMBER PALMTAG: So, on the verification, 11 I assume you'd covered verification, including all the 12 GE, the Westinghouse, the --
13 MR. SENECAL: Yes.
14 MEMBER PALMTAG: -- the new 11 x 11 BWR 15 fuel solvent for -- okay. Thank you.
16 MS. COLLIER: Thank you.
17 CHAIR MARTIN: And any last questions from 18 members? Okay, at the end of the open session we have 19 an opportunity for public comment. If there's anyone 20 in the room or online representing themselves, or an 21 external public organization, you have an opportunity 22 now to provide comments online, please, and raise your 23 hand, the Teams function. Can anybody in the room 24 just say something?
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
45 All right, not that we expected anything.
1 So, I think the silence says that we're done with this 2
open session.
3 So, at this point we will make a 4
transition to the closed and our staff will make sure 5
that everyone that should be in the room is otherwise 6
vetted.
7 So, we're going to take a break here and 8
let all that transpire.
9 (Whereupon, the above-entitled matter went 10 off the record at 9:27 a.m.)
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
NRC Staff Review of Framatome Topical Report ANP-10350P, Methodology for BWRs: Evaluation and Validation of APOLLO2-A/ARTEMIS-B Ashley Smith, NRR Alex Collier, NRR 1
Open Presentation to Advisory Committee on Reactor Safeguards Accident Analysis Subcommittee May 6, 2025
Agenda
- Introduction
- Review Timeline
- Regulatory Requirements and Guidance
- Technical Evaluation (Open Session)
- Neutronic Methodology
- Thermal Hydraulic Methodology
- Fuel Rod Module Methodology
- Validation and Verification
- Power Distribution Uncertainty
- Increased Enrichment and High Burnup Supplement
- Limitations and Conditions
- Conclusions 2
Introduction
- Applicable to steady state BWR core modeling
- Methodology and V&V 3
4
- APOLLO2-A/ARTEMIS-B is an extension of the ARCADIA code system to BWRs including:
- APOLLO2-A spectral code
- ARTEMIS-B core simulator
- Cross-section functionalization code HERMES-B
- ARTEMIS and HERMES codes extended
- BWR specific models adapted from MICROBURN-B2 BWR core simulator.
Introduction
5 2022 2025 Today 2022 2023 2024 2025 TR submittal Jun 30 Acceptance Review Aug 18 Audit 1 Dec 5 1st Round RAIs Jan 15 2nd Round RAIs Apr 1 1st Round RAI Responses Jun 2 2nd Round RAI Responses Oct 7 Supplement Feb 1 Audit 2 May 28 3rd Round RAIs Jul 1 3rd Round RAI Responses Oct 2 Draft SE Feb 10 ACRS SC May 6 ACRS FC Jun 22 Review Timeline Framatome NRC
Regulatory Requirements and Guidance
- NUREG-0800, Standard Review Plan, Chapter 4.3, Nuclear Design
- Fuel design limits will not be exceeded during normal operation or anticipated operational transients
- Postulated reactivity accidents do not compromise reactor coolant pressure boundary
- Core coolability is maintained 6
Regulatory Requirements and Guidance (Cont.)
- Reactor Design General Design Criteria 11
- Reactor Inherent Protection General Design Criteria 12
- Suppression of Reactor Power Oscillations General Design Criteria 13
- Instrumentation and Control General Design Criteria 20
- Protection System Functions 7
- Protection System Requirements for Reactivity Control Malfunctions General Design Criteria 26
- Reactivity Control System Redundancy and Capability General Design Criteria 27
- Combined Reactivity Control Systems Capability General Design criteria 28
- Reactivity Limits
Regulatory Requirements and Guidance (Cont.)
The NRC staff reviews the areas concerning analytical methods. These are:
Descriptions of the analytical methods used in the nuclear design, including those for predicting criticality, reactivity coefficients, burnup and stability.
The database and/or nuclear data libraries used for neutron cross-section data and other nuclear parameters Verification of the analytical methods for comparison with measured data.
8
Neutronic Methodology
- APOLLO2-A
- No computational models were added or changed since the ARCADIA topical reports
- The NRC staff considered the applicability of the current methodology to BWRs and found APOLLO2-A acceptable.
- HERMES-B
- NRC staff reviewed cross section fitting functions and interpolation points in an RAI
- The NRC staff found HERMES-B acceptable.
9
Neutronic Methodology (Cont.)
- ARTEMIS-B
- The NRC staff focused its review on BWR-specific models.
- Most of the added models are adapted from MICROBURN-B2, an NRC-approved core simulator.
- Framatome provided sensitivity study in an RAI with reactors representative of modern operating states
- The NRC staff found that the models added, and the overall methodology, are acceptable for BWR modelling.
10
Thermal Hydraulic Methodology
- Similar to MICROBURN-B2 core simulator
- Minor improvements made for ARTEMIS-B
- Uses an iterative calculation scheme
- NRC staff found that the TH methods were acceptable because they are consistent with approved methodologies and industry standards 11
Fuel Rod Module Methodology
- Comparable to ARTEMIS fuel rod module
- Physical properties consistent with RODEX4
- Effective fuel temperature equation consistent with MICROBURN-B2
- NRC staff concluded that the methodology is acceptable because it is consistent with approved industry standard codes 12
Validation and Verification APOLLO2-A V&V
- Critical Experiments
- Spent Fuel Measurements
- Numerical Validation ARTEMIS-B V&V
- Reflector Treatment
- Pin Power Verification
- Core Follow Benchmarks
- Gamma Scans Thermal Hydraulic Verification Fuel Rod Module Verification The NRC staff found that the verification adequately assessed the range of applicability expected and demonstrated that the predictive capability of the code system is acceptable.
13
Increased Enrichment and Higher Burnup Supplement
- Framatome requested to extend the range of applicability to include increased enrichment and higher burnup conditions
- Advanced Fuel Management (AFM) conditions
- Verification and validation of the extended conditions
- The NRC staff concluded that the APOLLO2-A/ARTEMIS-B methodology is acceptable for use at AFM conditions 14
Limitations and Conditions
- 1. Applicable to steady state operation
- 2. Limited to analyzing BWR fuel assemblies with square lattices and fuel designs validated within this TR
- Can be used with similar fuel designs if modeling remains within capabilities of the methodology and validation is performed.
- 3. ARTEMIS-B FRM is subject to L&Cs in the current RODEX4 SE. Enrichment and burnup limits remain at non-AFM conditions until RODEX4 is approved by the NRC staff at the higher limits requested in the supplement.
15
Conclusions
- The NRC staff found the ANP-10350P/NP APOLLO2-A/ARTEMIS-B methodology an acceptable approach for application to steady state neutronic design analysis of BWRs.
- The NRC staffs conclusions are predicated upon licensees acceptably addressing limitations and conditions in Section 4.0 of the NRC staffs safety evaluation.
16
- AFM - Advanced Fuel Management
- BWR - Boiling Water Reactor
- FRM - Fuel Rod Module
- L&Cs - Limitations and Conditions
- RAI - Request for Additional Information
- SE - Safety Evaluation
- TH - Thermal Hydraulic
- V&V - Verification and Validation 17
Framatome Methodology for Boiling Water Reactors: Evaluation and Validation of APOLLO2-A/
ARTEMIS-B ACRS Accident Analysis Subcommittee Meeting Open Session, May 6, 2025 Jaron Senecal
2 Content
- 1. Computer Codes
- 2. Methods and Models
- 3. Verification and Validation
Framatome Topical Report ANP-10350P - ACRS Subcommittee Meeting - May 6, 2025 © Framatome - All rights reserved 3
Computer Codes 1
Framatome Topical Report ANP-10350P - ACRS Subcommittee Meeting - May 6, 2025 © Framatome - All rights reserved 4
Approved methodologies o
BWR: CASMO4/MICROBURN-B2, EMF-2158P-A o
PWR: APOLLO2-A/ARTEMIS, ANP-10297P-A Methodology under consideration o
BWR: APOLLO2-A/ARTEMIS-B, ANP-10350P o
The first TR in a series of next generation codes and methods o
Applicable to steady-state calculations o
Includes supplement regarding increased enrichment and burnup Topical Report Background
Framatome Topical Report ANP-10350P - ACRS Subcommittee Meeting - May 6, 2025 © Framatome - All rights reserved 5
Lattice physics code o
Calculates the few group cross sections (XS) for the ARTEMIS-B core simulator Solves the 2D neutron transport equation o
Uses a 3 level computational scheme o
Uses 281 neutron energy groups and 94 gamma energy groups o
Uses the JEFF 3.1.1 cross sections with modifications Modifications defined in ANP-10297 Supplement 1P-A (ARCADIA)
No additional computational models were added since the ARCADIA topical reports APOLLO2-A
Framatome Topical Report ANP-10350P - ACRS Subcommittee Meeting - May 6, 2025 © Framatome - All rights reserved 6
HERMES-B is a cross section functionalization code o
The XS data are read directly from APOLLO2-A o
Creates a multi-dimensional functional representation of the XS o
Then the XS data can be calculated at any set of conditions o
Based on HERMES (ANP-10297), but with additional parameters The following data is functionalized:
o Microscopic XS o
Macroscopic Residual and Delta XS o
Pin Form Factors o
Discontinuity Factors o
Detector Reponses o
Heat Deposition Fractions HERMES-B
Framatome Topical Report ANP-10350P - ACRS Subcommittee Meeting - May 6, 2025 © Framatome - All rights reserved 7
ARTEMIS-B is the extension of the ARTEMIS core simulator to BWRs ARTEMIS-B uses much of the same methodology described in ANP-10297 ARTEMIS-B contains the following modules:
o Flux Module o
Fuel Rod Module o
Thermal Hydraulic Module o
Dehomogenization Module o
Depletion Module ARTEMIS-B
Framatome Topical Report ANP-10350P - ACRS Subcommittee Meeting - May 6, 2025 © Framatome - All rights reserved 8
Methods and Models 2
Framatome Topical Report ANP-10350P - ACRS Subcommittee Meeting - May 6, 2025 © Framatome - All rights reserved 9
The methods of several modules are unchanged relative to ANP-10297 (and Supplement 1) o Flux solver Uses the semi-analytical nodal expansion method with coarse mesh rebalancing o
Dehomogenization module Calculates the intra-nodal quantities such as pin powers and pin burnups o
Depletion module Uses a Krylov subspace method to solve the depletion matrix Components From ARCADIA
Framatome Topical Report ANP-10350P - ACRS Subcommittee Meeting - May 6, 2025 © Framatome - All rights reserved 10 ARTEMIS-B Fuel Rod Module (FRM) o Solves the 1D heat transfer equation:
o Solved for a representative fuel rod in a lattice o
Calculates the effective fuel temperature Comparison to ANP-10297 o
Same numerical solution method o
Properties have been updated to be consistent with RODEX4 (BAW-10247P-A)
Properties o
Pellet Radial Power Distribution o
Thermal Conductivity o
Gap Conductance o
Porosity Fuel Rod Module
Framatome Topical Report ANP-10350P - ACRS Subcommittee Meeting - May 6, 2025 © Framatome - All rights reserved 11 The TH module solves the fluid conditions in the core Thermal hydraulic geometry o
Equivalent to a system of parallel flow paths o
Each flow path is connected at the top and bottom of the core o
The main flow paths correspond to enclosed fuel assemblies o
There are additional flow paths for the bypass and internal water channel flows The ARTEMIS-B TH methodology is similar to MICROBURN-B2 Thermal Hydraulic Module
Framatome Topical Report ANP-10350P - ACRS Subcommittee Meeting - May 6, 2025 © Framatome - All rights reserved 12 Variable Axial Nodalization (VAX) Model Spacer Grid Model Detector Model Control Blade Depletion Model Control Blade History Model Reflector Model Jumpstart Model BWR-Specific Models
Framatome Topical Report ANP-10350P - ACRS Subcommittee Meeting - May 6, 2025 © Framatome - All rights reserved 13 Verification and Validation 3
Framatome Topical Report ANP-10350P - ACRS Subcommittee Meeting - May 6, 2025 © Framatome - All rights reserved 14 Three types of data are used:
o Critical Experiments Results: Reactivity and Fission Rate Distribution Experiments: BASALA, EPICURE, B&W, CAMELEON, ICSBEP o
Spent Fuel Measurements Fukushima Daini 1 (BWR)
Fukushima Daini 2 (BWR)
REGAL (PWR, 10% Gadolinium) o Monte Carlo Comparisons Used to span a much wider range of conditions and fuel types than experiments Validates: reactivity, pin powers, burnup, and gamma transport APOLLO2-A V&V
Framatome Topical Report ANP-10350P - ACRS Subcommittee Meeting - May 6, 2025 © Framatome - All rights reserved 15 Verification of the Fuel Rod Module o
Comparison made between the ARTEMIS-B FRM and RODEX4 to show consistency Reflector model numerical validation using SERPENT2 Verification of the ARTEMIS-B Pin Power Predictions o
Colorset calculations compared against APOLLO2-A Validation of the Thermal-Hydraulic Module o
Pressure drop data o
Channel average void fraction data Core Follow Results o
110 cycles from 8 different reactors Pin and Nodal Gamma Scan Results o
3 reactors / 5 cycles ARTEMIS-B V&V
Framatome Topical Report ANP-10350P - ACRS Subcommittee Meeting - May 6, 2025 © Framatome - All rights reserved 16 AFM - Advanced Fuel Management o
Maximum U-235 enrichment is increased o
Maximum full length fuel rod average burnup limit is increased V&V extended to AFM conditions o
APOLLO2-A Critical Experiments o
APOLLO2-A Numerical Validation o
ARTEMIS-B Pin Power Verification Supplement Regarding AFM
Framatome Topical Report ANP-10350P - ACRS Subcommittee Meeting - May 6, 2025 © Framatome - All rights reserved 17 The APOLLO2-A/ARTEMIS-B code system introduced An overview of the main code modules and models has been presented The verification and validation has been described Conclusion
Framatome Topical Report ANP-10350P - ACRS Subcommittee Meeting - May 6, 2025 © Framatome - All rights reserved 18 Thank you
Framatome Topical Report ANP-10350P - ACRS Subcommittee Meeting - May 6, 2025 © Framatome - All rights reserved 19 AFM Advanced Fuel Management BWR Boiling Water Reactor FRM Fuel Rod Module JEFF Joint Evaluated Fission and Fusion File PWR Pressurized Water Reactor TH Thermal Hydraulic TR Topical Report VAX Variable Axial Nodalization V&V Verification and Validation XS Cross Section Nomenclature
Framatome Topical Report ANP-10350P - ACRS Subcommittee Meeting - May 6, 2025 © Framatome - All rights reserved 20 ARCADIA and ARTEMIS are trademarks or registered trademarks of Framatome or its affiliates, in the USA or other countries.
Trademarks
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This document and any information it contains shall not be used for any other purpose than the one for which they were provided.
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