ML25112A095
| ML25112A095 | |
| Person / Time | |
|---|---|
| Issue date: | 04/02/2025 |
| From: | Advisory Committee on Reactor Safeguards |
| To: | |
| References | |
| NRC-0290 | |
| Download: ML25112A095 (1) | |
Text
Official Transcript of Proceedings NUCLEAR REGULATORY COMMISSION
Title:
Advisory Committee on Reactor Safeguards Docket Number:
(n/a)
Location:
teleconference Date:
Wednesday, April 2, 2025 Work Order No.:
NRC-0290 Pages 1-151 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 724TH MEETING 4
ADVISORY COMMITTEE ON REACTOR SAFEGUARDS 5
(ACRS) 6
+ + + + +
7 WEDNESDAY 8
APRIL 2, 2025 9
+ + + + +
10 The Advisory Committee met via 11 teleconference at 8:30 a.m., Walter L. Kirchner, 12 Chair, presiding.
13 COMMITTEE MEMBERS:
14 WALTER L. KIRCHNER, Chair 15 GREGORY H. HALNON, Vice Chair 16 DAVID A. PETTI, Member-at-Large 17 RONALD G. BALLINGER, Member 18 VICKI M. BIER, Member 19 VESNA B. DIMITRIJEVIC, Member 20 CRAIG A. HARRINGTON, Member 21 ROBERT P. MARTIN, Member 22 SCOTT P. PALMTAG, Member 23 THOMAS E. ROBERTS, Member 24 MATTHEW W. SUNSERI, 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 ACRS CONSULTANTS:
1 DENNIS BLEY 2
4 DESIGNATED FEDERAL OFFICIALS:
8 9
10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1716 14th STREET, N.W., SUITE 200 (202) 234-4433 WASHINGTON, D.C. 20009-4309 www.nealrgross.com
3 CONTENTS 1
Committee Discussion 2
NuScale Letter discussion and assignments.
4 3
NuScale Standard Design Approval Application Topics 4
Including NuScale Topical Reports on Extended Passive 5
Cooling and Reactivity Control Methodology and 6
Non-LOCA Methodology 6
7 Meeting called to Order, Chair Kirchner..... 98 8
Terrestrial Energy Topical Report on Principal 9
Design Criteria................
101 10 Adjourn 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1716 14th STREET, N.W., SUITE 200 (202) 234-4433 WASHINGTON, D.C. 20009-4309 www.nealrgross.com
4 P-R-O-C-E-E-D-I-N-G-S 1
(8:30 a.m.)
2 CHAIR KIRCHNER: The meeting will now come 3
to order. This is the first day of the 724th meeting 4
of the Advisory Committee on Reactor Safeguards, ACRS.
5 Im Walt Kirchner, Chairman of the ACRS. ACRS members 6
in attendance in person are Ron Ballinger, Greg 7
Halnon, Robert Martin, Scott Palmtag, Dave Petti, 8
Thomas Roberts, Craig Harrington, and Vicki Bier.
9 ACRS members in attendance virtually via teams are 10 Vesna Dimitrijevic and Matt Sunseri. Our consultants 11 participating today virtually are Stephen Schultz and 12 Dennis Bley, and if Ive missed anyone, consultants, 13 or members, please speak up now.
14 Mike Snodderly of the ACRS staff is the 15 designated Federal Officer for this morning's full 16 committee meeting. No member conflicts of interest 17 were identified, and I note that we have a quorum.
18 The ACRS was established by statute and is 19 governed by the Federal Advisory Committee Act, or 20 FACA. The NRC implements FACA in accordance with our 21 regulations. Per these regulations and the Committee's 22 bylaws, the ACRS speaks only through its published 23 letter reports. All member comments, therefore, 24 should be regarded as only the individual opinion 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
5 that member and not a Committee position.
1 All relevant information related to ACRS 2
activities, such as letters, rules for meeting 3
participation, and transcripts, are located on the NRC 4
public website and can be readily found by typing 5
about us ACRS in the search field on NRC's homepage.
6 The ACRS, consistent with the Agency's 7
value of public transparency and regulation of nuclear 8
facilities, provides opportunity for public input and 9
comment during our proceedings. We have received no 10 written statements or requests to make an oral 11 statement from the public. Written statements may be 12 forwarded to today's designated Federal Officer, and 13 we have also set aside time at the end of this meeting 14 for public comments.
15 A transcript of the meeting is being kept 16 and will be posted on our website. When addressing 17 the Committee, the participants should first identify 18 themselves and speak with sufficient clarity and 19 volume so that they may be readily heard. If you are 20 not speaking, please mute your computer on Teams, and 21 if you are participating by phone, press star 6 to 22 mute your phone and star 5 to raise your hand on 23 Teams. The Teams chat feature will not be available 24 for use during the meeting.
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 For everyone in the room, please put your 1
electronic devices in silent mode and mute your laptop 2
microphone and speakers. In addition, please keep 3
sidebar discussions in the room to a minimum because 4
the ceiling microphones are live. For the presenters, 5
your table microphones are unidirectional, and you'll 6
need to speak directly into the front of the 7
microphone to be heard online.
8 Finally, if you have any feedback for the 9
ACRS about today's meeting, we encourage you to fill 10 out the public meeting feedback form on the NRC's 11 website.
12 During today's meeting, the Committee will 13 consider the following topics: The NuScale standard 14 design approval application, including NuScale topical 15 reports on extended passive cooling and reactivity 16 control methodology and the non-LOCA methodology TR.
17 As stated in the agenda, portions of this 18 meeting may be closed to protect sensitive information 19 as required by FACA and the Government in the Sunshine 20 Act. Attendance during the closed portion of the 21 meetings -- closed portions of the meetings will be 22 limited to the NRC staff and its consultants, NuScale, 23 and those individuals and organizations who have 24 entered into an appropriate confidentiality agreement.
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 And we will confirm that only eligible individuals are 1
in the closed portion of that meeting.
2 And with that, I, as the subcommittee 3
chair for NuScale, we're going to depart a little bit 4
from the schedule I just mentioned to take up a topic 5
that we had requested NuScale address, and that is the 6
ECCS valve testing program.
7 And so, Mike, with that, do we have a 8
question-and-answer approach or are we going to have 9
to have a presentation?
10 MR. SNODDERLY: The NuScale staff that 11 will help in with Member Harrington's questions are 12 online.
13 CHAIR KIRCHNER: Okay. Which ones?
14 MR. SNODDERLY: And then the staff also 15 had some information.
16 So I guess, Member Harrington, did you 17 want to make a statement, I guess, what you were 18 looking for or -- but we have the staff available to 19 respond to questions concerning future plans for the 20 qual.
21 MEMBER HARRINGTON: This is Member 22 Harrington. On the Chapter 6 letters, in preparing 23 that after our review meeting a month ago or whenever 24 it was, now I looked back at the final DCA letter, 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
8 there were several topics from Chapter 6 in the DCA 1
that merited particular attention by the committee at 2
the time. I was not a part of the Committee at the 3
time, so some of this is secondhand in that regard, 4
for me at least.
5 But one of the topics that was raised and 6
carried through to the final letter was in regard to 7
the operability of the ECCS valves after sitting in 8
the operating environment of the containment reactor 9
vessel for the entire operating cycle, basically, and 10 whether the presence of boron or any other issues 11 might degrade the performance of the valve, basically 12 cause it to not open.
13 And the Committee position expressed in 14 that letter was that there was qualification program 15 plan. Qualification testing was specifically called 16 out in the letter that they felt would adequately 17 address that but also included a couple of comments in 18 that final letter in regard to topics that ought to be 19 addressed in that testing.
20 And so, the questions that I raised at 21 that point were kind of where are we now? What 22 testing was done? What information do we have now to 23 close out that issue more completely maybe than was 24 done in the DCA? Basically, what is the status now?
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 So that's, I guess, maybe a useful setup to those 1
questions, and I'd be interested in hearing from 2
NuScale in regard to that topic.
3 MR. BECK: Hey, Member Harrington, this is 4
Tyler Beck from NuScale and also have Dan Lassiter on 5
the phone.
6 Dan, I know you were having issues getting 7
in the meeting, so I just want to confirm. Did you --
8 are you in the meeting?
9 MR. LASSITER: This is Dan Lassiter. Can 10 you hear me?
11 MR. BECK: Yeah.
12 MR. LASSITER: Okay.
13 PARTICIPANT: Yes.
14 MR. LASSITER: Yep, but I did only catch 15 the last portion of the question. So, either if Tyler 16 can start, it could be restated shortly. That would 17 be appreciated.
18 MR. BECK: Yeah. So Dan, the question is 19 getting back to the DCA letter and discussion of 20 testing, and you know, addressing concerns related to 21 potential for something like boric acid buildup during 22 the longer-term period.
23 And so, to start addressing this question 24
-- and Dan, feel free to chime in if you 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
10 something else to say or Augie's there as well -- we 1
performed two test programs, representative and 2
prototypic valve testing thus far, to confirm the 3
ability and demonstrate the ability of the ECCS valves 4
and their functionality.
5 In addition to those test programs, we 6
include the ECCS valves in the scope of ASME QME-1 7
testing and then environmental qualification as well.
8 So you have those additional pieces to qualification 9
of the valves. And then, when the valves are in 10 service, you have in service testing during every 11 outage. And then lastly, there is a boric acid 12 control program included for the -- right now in the 13 scope of a COL item. But all of those components play 14 into ensuring that the valves won't have some type of 15 issue related to boric acid preventing their 16 functionality.
17 MR. LASSITER: Yeah, this is Dan Lassiter, 18 NuScale Design Engineering. I'll maybe just be a 19 little more detailed in the scope of what Tyler just 20 mentioned there.
21 In the DCA review, we did a test program 22 with the NRC, reviewing that program to support their 23 review. And we did use boric acid solution within the 24 valve components to demonstrate that in an actuation, 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 in the flashing and things like that, boron wouldn't 1
precipitate out and affect valve function. But that's 2
a short-term functional test.
3 The long-term effects of boric acid or 4
boron solution are addressed by the qualification 5
program. There's the QME-1 portion, which is 6
functional testing. That's not really long-term 7
effects. The long-term effects are really addressed 8
by the environmental qualification portion. And so, 9
that has not been carried out yet. But there are 10 requirements in qualification program to address any 11 long-term degradation mechanisms that could affect 12 safety function of the valve. And so, those will be 13 required to be addressed either by test or analysis or 14 justification in the qualification program.
15 And as Tyler mentioned, there's also, you 16 know, programs during plant operation to ensure 17 functionality of the valves. There's the IST program.
18 These are exercised every outage during the shutdown 19 process. The ECCS valves are, as well as the boric 20 acid inspection program, which is, as you mentioned, 21 a COL item, to develop that program. So we believe 22 that those programs, as well as the functional testing 23 and qualification, address the effects of boron or 24 boric acid solution, you know, in and around the ECCS 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 valves in the short term and also in the long term.
1 MEMBER HARRINGTON: Have you looked at any 2
-- I guess for me, in trying to pick up that concern 3
from the Committee several years ago, the area that 4
I'd be concerned about is small ports in tight 5
clearance areas that something might fake out, 6
precipitate out on, and challenge the valve. And 7
really, in the end, the challenge is could there be a 8
common mode failure that could affect multiple valves?
9 Have you looked at other operating experience? I'm 10 not sure there's other valves in the current fleet 11 that really sit in that same kind of environment as 12 warm as these would be.
13 MR.
LASSITER:
I
- mean, there's 14 pilot-operated safety valves which are similar in 15 design and function and in some similar environment.
16 I guess some of them are maybe more in the steam space 17 than the liquid space, but we have operating 18 experience of similar valves either that NuScale has 19 collected information, or the valve vendor provides 20 their -- valve supplier/designer supplies their, you 21 know, their expertise and operating experience.
22 You know, I think it's difficult to 23 definitively answer the concern today because it has 24 to be addressed through the qualification program, 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 which is not complete yet but will be prior to 1
operation. So I really have to lean on the fact that 2
any long-term degradation mechanism, you know, with 3
respect to valve safety function, is required to be 4
addressed, including chemistry and buildup of boron 5
precipitate in the environmental qualification 6
program. So that's the primary, primary mechanism.
7 MEMBER HARRINGTON: Well then, let me just 8
ask this, in the logical extreme, which maybe is not 9
logical in this case, but if there was a common mode 10 failure, what happens if none of this ECCS valves 11 open?
12 MR. BECK: Probably -- this is Tyler Beck.
13 Probably would be a question for either our PRA or 14 safety analysis folks, but I would imagine we would 15 get to a point where the reactor safety valves would 16 lift, and I'm not sure the event sequence after that.
17 MEMBER HARRINGTON: Yes, that's what I 18 would expect. Yeah.
19 MR. LASSITER: There's also a feature in 20 the ECCS valves described in Chapter 6. I don't want 21 to be too detailed here. The -- if the actuator does 22 not actuate, the valve is still open, once the RPV, 23 the reactor vessel is depressurized due to an internal 24 spring inside the valve. So and that's reflected 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
14 the PRA models and is a significant feature.
1 So that's a portion of the answer to your 2
question, but that is getting into a hypothetical 3
scenario. I think PRA would be best suited to answer 4
that question.
5 CHAIR KIRCHNER: This is Walt Kirchner.
6 Don't you -- you have to set these valves each time 7
with CVS, CVCS pressure. So, in effect, you will have 8
to exercise them each time or you won't be able to 9
start up that module because youre going -- if they 10 were not seated properly, you're not going to be able 11 to pull a vacuum in the containment.
12 MR. LASSITER: Yep, that's exactly 13 correct, yeah. They're exercised and open during the 14 shutdown process, and then they're reset and closed 15 during the startup process.
16 CHAIR KIRCHNER: So therell be a 17 functionality test with each outage for refueling.
18 MEMBER HARRINGTON: I guess for those of 19 you that were here when the letter was written, does 20 that keep that issue in a comfortable place?
21 CHAIR KIRCHNER: Well, at the time there 22 was a commitment, and I believe some of this valve, 23 the ECCS valve testing program was executed, and it 24 sounds like now they're continuing the qualification 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 program. So that was one of those concerns that was 1
flagged in that letter we were coming out of the DCA.
2 But the fact that they have to actuate 3
they have to actually seat those valves each time is 4
probably a good test of whether the ports have that 5
buildup of boric acid or of any kind of blockage that 6
would impair their operability. And if they don't get 7
a good seating of the valve, then they're not going to 8
have a leak tight system and be able to pull a vacuum 9
on the containment. So there is in effect a retest of 10 each of the valves with each outage cycle.
11 MEMBER BALLINGER: Yeah.
12 CHAIR KIRCHNER: Go ahead, Ron.
13 MEMBER BALLINGER: This is Ron Ballinger.
14 I think I'm the one that brought that up in the 15 original DCA because I had a lot of experience with on 16 the BWR side, solenoid-operated and pilot-operated 17 relief valves that have a habit of not lifting within 18 specification. So there was an operability issues 19 that I was worried about, and I think what they've 20 said since they -- it has to be operable, and they 21 have to test it prior -- at the end of each outage, 22 right?
23 CHAIR KIRCHNER: Right.
24 MEMBER BALLINGER: That's the same thing 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 that they have to do on the BWR side, or they -- these 1
are safety valves.
2 CHAIR KIRCHNER:
- Dennis, you also 3
contributed to that part of the review for the DCA.
4 Do you have any comments on this or questions?
5 DR. BLEY: Sorry. I had trouble getting 6
my microphone. Nothing further than you folks have 7
already talked about. I don't completely remember the 8
discussions back then, but no, nothing more to add.
9 CHAIR KIRCHNER: Okay. All right. So 10 does the staff have anything to add at this point?
11 (Simultaneous speaking.)
12 PARTICIPANT: Tom Scarbrough is supposed 13
-- Tom Scarbrough our next -- he just walked in.
14 CHAIR KIRCHNER: Tom, when you sign in, 15 the floor is yours.
16 (Laughter.)
17 CHAIR KIRCHNER: Time to get prepared.
18 Oh, by the way. Okay, we'll put you on the spot if 19 you just stand right there.
20 MR. SCARBROUGH: Sure.
21 CHAIR KIRCHNER:
- Yeah, that's the 22 microphone.
23 MR. SCARBROUGH: Okay.
24 CHAIR KIRCHNER: So we're just having 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
17 discussion about the ECCS valves and qualification 1
program. Can you give us kind of an update of where 2
the staff review is on the valve test program?
3 MR. SCARBROUGH: Right, sure. I'll be 4
glad to. Where we are, the DCA, we went through a 5
very elaborate review of the 50.43(e) testing program, 6
including capability, boron, boric acid solution, and 7
all that. We went through and wrote a very long audit 8
report that described all of that and what type of 9
testing they did. And then at the conclusion, we said 10 that all these lessons learned will need to be 11 incorporated into the QME-1 qualification program.
12 And that was very, very specified.
13 Now, working with the SDA, we had 14 discussions with them, and they did a series of tests 15 of temperatures, and they found a lot of interesting 16 things that they're going to address as part of the 17 QME-1 qualification.
18 Now for the boron, they were able to make 19 a reasonable argument that from a 50.43(e) test 20 perspective, they did not need to do the boric acid 21 testing that they did before because nothing really 22 changed significantly in the dimensions of the -- of 23 those valves. So we allowed them to do that.
24 So we completed the 50.43(e) review 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
18 the SDA for the ECCS valves. And we summarize the 1
reports. The reports were all proprietary, but we 2
summarized them in the
- SER, you
- know, the 3
non-proprietary version of what we looked at. And 4
they went through all types of things: CB testing, XT 5
testing. They did a number of different type things 6
to demonstrate capability of the valves from a 7
50.43(e) perspective. And so, we completed that. We 8
wrote the safety evaluation and made a finding that 9
from a 50.43(e) perspective, they had justified it.
10 They didn't do the boric acid testing for 11 this one, but the other parts we thought were 12 reasonable, and we thought we could take lessons 13 learned from the DCA testing to complete that portion.
14 Now the next step will be the 15 qualification scheme. We want qualification testing.
16 And in the ITAAC, there's a specification that, a 17 design commitment that they qualify the valves for all 18 design basis conditions. And so, that would include 19 the whole gamut of testing, you know, in terms of the 20 IEBs, the RDVs, RRVs, all that will have to be tested 21 for the qualifications testing.
22 And so, they haven't relayed to us. I've 23 heard that they're thinking about it. They're 24 planning. They're doing the testing plans that they 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 would -- I think they would like to probably talk to 1
us sometime, so we can give some feedback to them.
2 And so, when they're ready, we'll be ready to talk to 3
them about what their plans are for full-scale QME-1 4
qualification test. But we're not there yet.
5 Well, when we did the testing for the DCA 6
50.43(e), they came in early. We looked at their test 7
plans. We gave them some feedback. They made some 8
adjustments, and we were able to proceed with the 9
50.43(e) testing for the DCA. It all went very 10 smoothly. So we're hoping the same thing will happen 11 for the QME-1 qualification testing for either the DCA 12 or the SDA whenever they're ready.
13 So that's sort of where we are. We're 14 sort of in the process of just waiting for them to be 15 ready to talk to us, and we'll be glad to talk to them 16 whenever. So that's where we are. They have -
17 theyve completed 50.43(e) testing satisfactorily. We 18 described that in SER. The next step will be for them 19 to come in and start talking about what their plans 20 are for QME-1 qualification testing. That's sort of 21 where we are.
22 CHAIR KIRCHNER: Okay. Thank you.
23 MR. SCARBROUGH: Okay. Sure. The other 24 thing I was going to mention, yesterday, we talked 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 lot about 50.69, and Getachew pointed out to me that 1
the DCA is not allowed to use 50.69 because it's a 2
design certification, but the SDA, they could. So, if 3
NuScale wanted to, they could come in under 50.69. I 4
just wanted to clarify that. Okay. Great. All 5
right. Thank you.
6 CHAIR KIRCHNER: Thank you.
7 MR. SCARBROUGH: Thank you.
8 CHAIR KIRCHNER: Okay.
9 MEMBER DIMITRIJEVIC: Walt?
10 CHAIR KIRCHNER: Yes. Go ahead, Vesna.
11 MEMBER DIMITRIJEVIC: Hi. Good morning.
12 In the PRA, you know, the concerns we also -- that was 13 one of the -- it was a number one consideration which 14 says that I was looking for this letter that further 15 examination of the design of emergency core cooling 16 system valves and associated PRA model is needed to 17 help to build confidence that plant risk is accurately 18 represented.
19 And this, in the PRA, we always express 20 concerns that the failure rates, the common cause 21 assumptions, and you know that the other underlying 22 conditions are realistically represent because those 23 are the most and the only important components in the 24
-- from the PRA perspective, cooling perspective.
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 So I just wanted to add that that thing 1
you know was left open in the reconciliation saying 2
the ECCS valve performance work will say the, you 3
know, the -- you know, is waiting for the development.
4 So, you know, it was left open and that's with now 5
discussion means in the in DCA -- PRA letter. Okay.
6 CHAIR KIRCHNER: Okay. Thank you.
7 Matt, go ahead.
8 MEMBER SUNSERI: Yes. Good morning. Hey, 9
so I've been listening to the conversation. I've been 10 thinking back on our meetings when we discussed these 11 valves before, and what I'm hearing is a pretty robust 12 program for establishing functionality of the valves, 13 qualification of the valves. I did check tech specs.
14 There are going to be periodic surveillance testings 15 of the valve at the end of cycle, in between cycles.
16 So I don't know why we would be concerned about this.
17 It's not like they're going to be in a environment 18 that is unfamiliar or unchallenged in the history of 19 pressurized water reactors. So I wouldn't have any 20 concern.
21 CHAIR KIRCHNER: Good. Thank you.
22 Okay. I think we can move on. Great.
23 Okay. So, with that, we're going to turn to Member 24 Martin, and he'll give us his assessment on the loss 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 of -- non-loss-of-coolant analysis methodology TR.
1 Okay.
2 MEMBER MARTIN: Thanks, Walt. To kind of 3
just familiarize us with the -- the agenda title is 4
the next couple hours or more we're going to talk 5
about the topical reports. One is the, of course, the 6
one I'm about to read in at the moment is Scott's on 7
extended passive cooling and reactivity control.
8 We had our meetings last month. I have 9
prepared a summary report, and that's all -- you see 10 it here on the screen here for all of us to see as I 11 read through it. I don't know if we're going to do an 12 editing. We've passed it around a little bit here 13 among committee, but I'm going to read it in, and I'll 14 pass it off to the -- our transcribe guy. What's the 15 right word for that?
16 PARTICIPANT: Court reporter.
17 MEMBER MARTIN: Thank you. So that he'll 18 have it so --
19 (Simultaneous speaking.)
20 MEMBER PETTI: Can you make it bigger?
21 Can someone --
22 (Simultaneous speaking.)
23 MEMBER MARTIN: Yeah, I think -- who has 24 it? Sandra has it. I'm going to read my copy which 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 I think is the same copy.
1 MEMBER PETTI: Yeah, that's better. Thank 2
you.
3 MEMBER MARTIN: Okay. It's just we also 4
have it in our P&P for later. Anyway, I'll begin now.
5 Member Martin reviewed NuScale's Topical 6
Report TR-0516-49416 Non-Loss-of-Coolant Accident 7
Analysis Methodology Revision 4 -- and I will not 8
provide the ADAMS number -- describing the non-LOCA 9
evaluation model (EM) for design-basis transient 10 analyses and the 250-Megawatt thermal NuScale Power 11 Module (NPM-20). The Committee reviewed a previous 12 version of this TR in 2020 for use with the 13 160-Megawatt thermal NPM-160, providing a letter at 14 that time. Revision 4 updates the model to support 15 the upgraded US460 design.
16 On March 4, 2025, NuScale and NRC staff 17 presented the revised TR and supporting analyses to 18 the Committee. The non-LOCA EM follows established 19 regulatory guidance, including RG 1.203 and the 20 NuScale Design-Specific Review Standard, and retains 21 key elements of the previously approved methodology, 22 including event classification, system response 23 analyses, and demonstration of fuel and radiological 24 safety criteria without operator action for 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br />.
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 The applicant affirmed that the methodology identifies 1
limiting single failures, accounts for the potential 2
negative influence of non-safety system actions and 3
includes bounding assumptions as appropriate.
4 The NRC staff's review concluded that the 5
revised evaluation model supports a finding of 6
reasonable assurance of safety, subject to ten 7
Limitations and Conditions, i.e. L&Cs. Most L&Cs are 8
consistent with those applied in previous approved 9
methodology; however, several were updated to reflect 10 changes in the NPM-20 design and modeling tools.
11 Among these, L&C No. 4 -- requiring evaluation of 12 biases on decay heat removal system heat transfer and 13 non-LOCA analyses -- was a focal point of discussion 14 during the Subcommittee meeting. The staff cited 15 concerns related to scaling and modeling uncertainty 16 as justification for evaluation of biases, despite 17 NuScale's presentation of test data and analyses 18 intended to support the adequacy of the realistic DHRS 19 model.
20 The Committee concludes that the revised 21 non-LOCA EM remains technically sound and sufficiently 22 conservative for evaluating the NPM-20's response to 23 design-basis transients. This conclusion is supported 24 primarily by its continuity with an already approved 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 methodology and a reaffirmed focus on dominant 1
phenomena and critical figures of merit. In addition, 2
the Committee has no objection to the staff issuing 3
their safety evaluation report; however, Martin 4
recommends removal of L&C No. 4. The continued 5
evaluation of biases on DHRS heat transfer is 6
unwarranted as the underlying uncertainty relates to 7
standard design considerations, not unmodeled 8
phenomena or scaling distortions. The steam generator 9
DHRS configuration reflects well-understood 10 industrial heat exchange principles, where 11 sufficiently sized heat transfer surface area ensures 12 heat rejection with minimum sensitivity to 13 uncertainty. Given NuScale's new test results and 14 modeling that shows the system maintains ample margin 15 to avoid overpressure, biases needlessly double-count 16 conservatism (in both design and analysis) and 17 undermines the credibility of NuScale's validated 18 approach.
19 It is recommended that this writeup serves 20 as the record of Subcommittee meeting and that an ACRS 21 letter report not be prepared.
22 So could be some discussion here related 23 to my conclusion on L&C No. 4. So I spent a little 24 time kind of -- you know, actually, I prepared a lump 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 parameter model kind of looking at basic heat transfer 1
performance and looked at some of the codes standards 2
that apply in this particular case. Frankly, you 3
know, with normal design practices there's going to be 4
very little sensitivity to the uncertainties that 5
we're talking about unless you really hit it really 6
hard to the point where you basically distort it from 7
reality. I do find that it's important that NuScale 8
did do those tests and did show really level of 9
sensitivity -- and we're talking about sensitivity 10 related to pressure in this particular case.
11 So that's primarily the basis of my 12 conclusion that the L&C is really unnecessary and that 13 design -- standard design practices would otherwise 14 account for the uncertainty that they're concerned 15 with.
16 CHAIR KIRCHNER: So Bob, yeah, we have two 17 issues here, just so that everyone appreciates what's 18 going on.
19 We've adopted a practice of late to unless 20 we think there are significant issues with material 21 that we're reviewing -- and this isn't NuScale 22 specific -- across the board, we've been adopting a 23 practice of using summary reports. Those are recorded 24 as part of the meeting minutes and are available 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
27 the public and also provided to the Commission. This 1
is in the interest of efficiency of operation of the 2
Committee so that we reserve the bulk of our time to 3
focus on safety significant matters.
4 The process issue here is that we have a 5
recommendation from one of our members. It happens to 6
be Bob this time, but we've had this in the past. So 7
we need to look at how do we capture this and how if 8
we're elevating it and we're not writing a letter 9
report, how do we disposition something like this? Or 10 is it just something that is a note to the staff that 11 we have a concern, but it doesn't rise to the level of 12 a letter report and such? So there's the process part 13 here and then there's the technical part.
14 MEMBER MARTIN: So, obviously --
15 CHAIR KIRCHNER: Let's start with the 16 technical part, and then we'll go to the process part.
17 MEMBER MARTIN: Okay. I was going to go 18 the other way but, again, I've kind of laid out -- I 19 mean, I could pull up my plot if you like.
20 But you know, there are, you know, 21 standards that are to get applied in the design 22 process. It's, you know, heat exchangers is not an 23 unfamiliar type application, basically a boiler 24 condenser kind of environment where the only thing 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 that really matters is surface area, total surface 1
area. You know, this is undergraduate-level type 2
work. I mean, no offense, but this is not hard stuff.
3 And you incorporate, you know, whether you 4
want to call the factor safety or what have you, you 5
account for, you know, long-term fouling that, you 6
know, results in oversize and you know, to then, you 7
know, back off even further, you end up getting 8
yourself into what might actually be a very steep 9
curve of sensitivity, which is very unrealistic if you 10 over -- if you use the word penalize, but you 11 penalize, basically, the heat transfer in that model, 12 and it very much distorts what's going on. And 13 NuScale did the work.
14 CHAIR KIRCHNER: Basically, we had boiling 15 on one side and condensation on the other. So we got 16 big heat transfer coefficients.
17 MEMBER MARTIN: Yeah.
18 CHAIR KIRCHNER: So this is not like a 19 fouling factor for a conduction heat transfer problem.
20 MEMBER MARTIN: No, no.
21 CHAIR KIRCHNER: So are there any 22 scenarios where, for some reason, the function, the 23 timing of the valve in isolation would result in a 24 solid system where you wouldn't have the opportunity 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 to boil and condense?
1 MEMBER MARTIN: I don't think we saw that.
2 CHAIR KIRCHNER: I mean that would be a 3
much bigger decrement on the heat transfer capability 4
than a fouling factor or penalty on anything.
5 PARTICIPANT: He had that much water. I'm 6
not sure that'd be a concern.
7 CHAIR KIRCHNER: Yeah.
8 MEMBER MARTIN: Yeah, that would give you 9
even more margin to think that they were using the 10 figures of merit.
11 But if, you know, the transition to the 12 process part -- I mean, somewhat, this is water under 13 the bridge, right? I mean, here we are, you know, 14 near the end of the whole process. There's nothing 15 fundamentally wrong with the safety evaluation report.
16 Clearly, NuScale has probably moved on a little bit.
17 But I just thought that, in this case, that by 18 presenting the L&C No. 4, they kind of identified as 19 a safety issue that I don't think is a safety issue.
20 And I think while we focus on safety 21 issues, it's also important to highlight when maybe 22 it's not a safety issue, that, you know, we should not 23 be, you know, standing behind things that are -- that 24 may be overly conservative in this case, particularly 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 given the investment that NuScale did into the testing 1
and what have you.
2 And it's, you know, in today's day and 3
age, I think it's important to just highlight, maybe 4
not overemphasize, but certainly highlight a situation 5
where, you know, maybe we should, you know, 6
acknowledge the efforts of an applicant into trying to 7
resolve an issue and that indeed there are some people 8
here that concur with the effort and that it is 9
adequate and not a safety issue.
10 I cut you off, David.
11 MEMBER PETTI: No, no, you, basically, 12 knew exactly where I was going. I agree with you 13 technically, but I worry that buried in the summary is 14 just the wrong thing. It's a recommendation. I think 15 it's an important recommendation in its specificity 16 here. But it's in its -- when you genericize that and 17 think about, you know -- sometimes I read some of the 18 L&Cs, and I'm going, really? You know, the 19 excessiveness, given the data that's behind it, is an 20 important consideration. I just don't know how we --
21 without writing a letter on it, I don't know how we 22 get it.
23 MEMBER MARTIN: Well, first I got --
24 MEMBER PALMTAG: This is Scott. This came 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 up last meeting. It is kind of a concern of ours. It 1
was kind of a little bit about the timing because 2
we're doing these reviews and the chapter memos. And 3
so, it's my understanding that these summaries, that 4
any conclusions would roll up into the Chapter 15 5
chapter summary.
6 MEMBER MARTIN: It was my intent to throw 7
this into the memo.
8 VICE CHAIR HALNON: So, from a process 9
perspective, there's a couple ways of handling it.
10 But what I would recommend is that you change it from 11 a recommendation to a conclusionary statement saying 12 the Committee feels that this L&C is unnecessary for 13 the following reasons and leave it at that. And then 14 in your Chapter 15
- memo, you can make the 15 recommendation to remove it, which will roll up into 16 the NuScale memo.
17 MEMBER MARTIN: I thought about the word 18 conclusion. I thought, well, maybe that was a litmus 19 for elevating it to a letter.
20 VICE CHAIR HALNON: Yeah, just a couple 21 things. You don't want to just highlight yourself.
22 Member Martin suggests or recognizes -- this a 23 committee summary. We all really buy into it or not.
24 I think you have general agreement, especially what 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 they've said relative to the confluence.
1 This seems like a lot. But if you make it 2
a conclusionary saying that, you know, this is clearly 3
unnecessary for the following reasons. They did a lot 4
of testing. They should be credited for that. Blah, 5
blah, blah. And then make the recommendation 6
appropriately in your 15 letter, and then we all can 7
-- well, as a committee, we'll decide if that goes in 8
the final.
9 MEMBER MARTIN: Get away from the word 10 recommends to concludes?
11 VICE CHAIR HALNON: In this.
12 CHAIR KIRCHNER: I would just put it as --
13 VICE CHAIR HALNON:
Make it a
14 conclusionary statement. You don't say conclude. Oh, 15 just say that -- Sandra, could you put line 34 back 16 up, please, or thereabouts?
17 So you could say we recommend. You said 18 we not only say we recommend, the Committee considers 19 the L&C No. 4 being unnecessary for -- and then you --
20 CHAIR KIRCHNER:
Just make it an 21 observation statement of fact rather than a buried 22 recommendation.
23 VICE CHAIR HALNON: That's a conclusionary 24 statement. That's probably the right word for it, 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
33 Walt said it better, just an observation of fact. And 1
the rest of it's fine.
2 MEMBER PETTI: So I'm worried. I said 3
this last time. This Chapter 15 memo is going to be 4
huge. There's no reason to say we can't just take 5
this on the topical, and make it a memo in and of 6
itself in the back of the package because it's such an 7
important -- I mean, you know, all of these ones, as 8
opposed to just putting it under the chapter, just 9
going to make it really --
10 (Simultaneous speaking.)
11 VICE CHAIR HALNON: You can turn this into 12 a memo, actually.
13 MEMBER MARTIN: And then I'll -- I was 14 going to take my summary report from LOCA, the summary 15 report for this, summary report from Scott, and then 16 and weave the story. I mean. Yes, Mike.
17 MR. SNODDERLY: So I think this is some 18 good timing though. This will lead well into the 19 outline. But when we go over the final letter 20 outline, there's an appendix that will have all of the 21 review memos. So and you could put in the text, or 22 you know, the body of the final letter some pointer to 23 that, to the Chapter 15 memo or the observation.
24 So you've got -- but of course, 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
34 topical report will already have been issued probably.
1 You know, again, not all this time is happening right 2
at the same time. For a little while that, you know, 3
took normally to write, the topical would have been 4
issued earlier or, you know, where you could have 5
given this insight. I was just trying to tell you 6
there's opportunities for you to make it to make the 7
public or interested parties well aware of where 8
there's additional information.
9 CHAIR KIRCHNER: Yes, yeah. Vesna, go 10 ahead.
11 MEMBER DIMITRIJEVIC: I just want to 12 mention that in the PRA there is a basic event which 13 models the fail of DHRS strain passive heat transfer 14 to reactor pool that has a failure probability of 40 15 minus 6, and you know, with uncertainty distribution.
16 So I don't really know that how is this estimated, but 17 it could be -- I mean this could be related. This 18 says that following successful actuation of DHRS 19 strain, this event represents a failure of passive 20 heat transfer nature circulation to the OHS over the 21 mission time. So maybe this L&C is connected to 22 estimating this failure probability.
23 MEMBER MARTIN: That did not come up in 24 our discussion on March 4th or whatever I have on 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 here. You know, what was presented to us related to 1
scaling distortions and just uncertainties that the 2
staff felt were unquantified.
3 (Simultaneous speaking.)
4 VICE CHAIR HALNON: We don't need to make 5
this hard from a process perspective. Dave had a good 6
suggestion, but since we do summaries of TRs in the 7
P&P summary, I would just put -- I mean, if you're 8
willing to turn this into a memo as a standalone, then 9
you can make your recommendation, or if you want to do 10 it in Chapter 15, it's fine. If you do it in your 11 Chapter 15 memo, then just make that an observation.
12 MEMBER MARTIN: Sure.
13 VICE CHAIR HALNON: And roll it up. If 14 you want to do a memo on it, then we'll just put the 15 title and CR and say there's a memo written on this.
16 You can write the memo on it. But I would suggest you 17 just roll it up.
18 MEMBER MARTIN: That's my plan.
19 VICE CHAIR HALNON: Since you want to 20 weave that story together.
21 MEMBER MARTIN: Right. And it's -- and 22 the memo is due really soon.
23 CHAIR KIRCHNER: So are you amenable, Bob, 24 to making this kind of a third-person thing 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
36 MEMBER MARTIN: Well, I mean, obviously 1
going into this discussion, I have to make it a 2
first-person now that I, you know, it sounds like I 3
have some consensus on the Committee, and I can change 4
it from first to third person.
5 CHAIR KIRCHNER: And I would put it at the 6
end before you sign off there. It is recommended. We 7
effectively have it there.
8 VICE CHAIR HALNON: You got what you 9
needed?
10 MEMBER MARTIN: I think so. I think I 11 have.
12 VICE CHAIR HALNON: Okay. So we can move 13 on.
14 MEMBER MARTIN: Should I have this revised 15 for P&P, Larry?
16 MR. BURKHART: Well --
17 MEMBER MARTIN: I mean, it won't take. I 18 mean I can have it revised for P&P.
19 MR. BURKHART: We can do that.
20 VICE CHAIR HALNON: Yeah, you've got all 21 day to take it.
22 MR. BURKHART: Revised, yep.
23 CHAIR KIRCHNER: All day and all night.
24 (Laughter.)
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 MEMBER MARTIN: Plenty of time.
1 CHAIR KIRCHNER: Okay. Thank you. Thank 2
you, Bob. Okay.
3 With that, we're going to turn to Scott 4
Palmtag who led the review on the ER or extended 5
cooling.
6 MEMBER PALMTAG: Not used to being longer 7
than Bob. All right. Some of the process issues are 8
going to show up in this one, too.
9 On March
- 4th, 2025, the NuScale 10 subcommittee of the ACRS reviewed the NuScale Topical 11 Report (TR) Extended Passive Cooling and Reactivity 12 Control Methodology Revision 0. This TR describes the 13 methodology to evaluate the emergency core cooling 14 system (ECCS) and decay heat removal system (DHRS) 15 extended passive cooling (XPC) function. Report is 16 applicable to both loss-of-coolant accident (LOCA) and 17 non-LOCA design basis events and shows compliance with 18 regulatory requirements 10 CFR 50.46(b)(4) and for 19 long-term cooling, and 10 CFR 50.46(b)(5) for coolable 20 geometry. The report also shows compliance with 21 General Design Criteria (GDC) GDC 26, GDC 27, GDC 34, 22 and GCD 35.
23 In the XPC LTR, NuScale presents the 24 Figure of Merits (FOM) selected for the XPC evaluation 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 model. These include (a) subcriticality, (b) coolable 1
- geometry, which is boron concentration below 2
solubility limit for precipitation, and (c) collapsed 3
liquid level above the top of the active fuel. The TR 4
shows that coolable geometry is retained and the 5
collapsed liquid level remains above the active fuel 6
- height, and the Committee agrees with these 7
conclusions. The Figure of Merit for subcriticality 8
is discussed below.
9 This TR also successfully addresses a 10 concern previously raised by the ACRS in 2020 and 11 describes additional shutdown control methods that 12 have been added since the US600 design so that an 13 exception to GDC 27 is not required.
14 Subcritical configurations. The US460 15 design did not request an exception to GDC 27.
16 Consistent with SECY-18-0099, GD 27 has historically 17 been interpreted as, quote, requiring a reactor to be 18 reliably controlled to achieve and maintain a safe, 19 stable condition, including subcriticality beyond the 20 short term, unquote. The ability to remain 21 subcritical after an ECCS actuation depends on the 22 behavior of several core parameters that affect core 23 reactivity. These include the following.
24 One, an initial concentration of boron is 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 present in the coolant at the beginning of the event 1
and will increase or distill in the core region due to 2
coolant boiling during natural circulation.
3 Two, additional boron is being added from 4
the dissolver baskets present in the containment 5
vessel. This adds negative reactivity.
6
- Three, the core is cooling down 7
substantially over the 72-hour period, which adds 8
positive reactivity.
9 Four, xenon first peaks, then decays away 10 over the 72-hour period. At 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br />, the Xenon is 11 almost gone which adds positive reactivity.
12 Five, all control, rods except the 13 highest-worth rod, are considered inserted, which adds 14 negative reactivity.
15 Six, samarium is increasing in the core 16 over the 72-hour period. This adds negative 17 reactivity.
18 It should be noted that some parameters 19 that are considered beneficial to core cooling, such 20 as low temperatures and low decay heat, quote, hence 21 low xenon, make it more difficult to remain 22 subcritical.
23 The most limiting conditions to remain 24 subcritical occur at the end of cycle, or EOC, when 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 the RCS boron concentration in the core is near zero.
1 From the cases shown in the TR and in Chapter 15, all 2
analyzed cases remain subcritical critical, but the 3
margin of criticality can be relatively small. The 4
smallest margin to criticality shown is 28 parts per 5
million (ppm) boron. This margin is in criticality is 6
within the predicted boron concentration uncertainty 7
usually observed in pressurized water reactors (PWRs),
8 which is typically 50 to 100 ppm. Cold, off-nominal 9
conditions usually increase the amount of uncertainty.
10 NuScale has indicated that there are many 11 conservatisms built into the analysis that increase 12 the margin to criticality, such as the use of 13 conservative temperatures in the analysis. The NRC 14 staff has also run computational fluid mechanics (CFD) 15 calculations that show that there is additional 16 conservatism in the NuScale boron tracking model.
17 To provide confidence that the reactor 18 remains subcritical during an ECCS event, NuScale 19 should quantify the conservatisms in their models and 20 show that each core loading pattern remains 21 subcritical during an ECCS event with sufficient 22 margin to account for uncertainties. Historically, a 23 shutdown margin of at least 1 percent has been used to 24 account for uncertainties. A 1 percent shutdown 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
41 margin in k-effective corresponds to approximately 100 1
ppm boron.
2 Each new core loading pattern should 3
demonstrate this shutdown margin. This can be done by 4
making by adding technical specification 5
requirements that are part of the Core Operating 6
Limits Report (COLR). NuScale already has technical 7
requirements to the operation of the Emergency Core 8
Cooling System Supplemental Boron (ESB) so the 9
existing requirements could be reviewed and modified 10 to demonstrate ECCS shutdown margin with 11 uncertainties.
12 Moving to additional Riser Holes. The TR 13 addresses a concern that the Committee has raised in 14 the past. On July 29th, 2020, the Committee wrote a 15 letter on boron distribution for the US600-certified 16 design. In that letter, the Committee identified a 17 potential issue where, after ECCS actuation, water 18 levels could drop below the riser holes and render 19 them ineffective; thus, coolant in the downcomer would 20 deborate for a range of design basis accidents, 21 including small-break LOCAs. Operator recovery 22 actions would raise the possibility of an influx of 23 deborated water into the core, which may result in 24 recriticality, return to power, and the potential 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
42 core damage. In the latest TR, NuScale addresses 1
these concerns, or this concern, by making a design 2
modification to the US460 that adds additional riser 3
holes at the midplane level of the steam generators 4
that would maintain a flow of borated water to the 5
downcomer, which would prevent this influx of 6
deborated water from occurring. In addition, the 7
US460 design has added boron baskets to the reactor 8
containment to further reduce the risk of risk of 9
recriticality during an ECCS event.
10 Conclusion. The NuScale Subcommittee of 11 the ACRS has reviewed the NuScale Topical Report. The 12 Subcommittee has the following recommendations and 13 comments.
14 One, a technical specification limit 15 should be added to show that the reactor core remains 16 subcritical for a period of 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br /> following an ECCS 17 actuation. This requirement should be added to the 18 Core Operating Limit Report and required for each 19 cycle. The subcritical analysis should account for 20 uncertainties during the ECCS event.
21 Two, NuScale has successfully addressed 22 the concerns raised in the ACRS letter from July 29th, 23 2020, by adding additional riser holes at the midplane 24 level of the steam generators. Without these riser 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
43 holes, there was a concern that an influx of deborated 1
water could enter the core and cause a recriticality.
2 In addition, the US460 design has added boron baskets 3
to the reactor containment to further reduce the risk 4
of recriticality during the ECCS event.
5 These comments will be deliberated by the 6
ACRS full committee for inclusion in the Chapter 15 7
review memo.
8 CHAIR KIRCHNER: Discussion.
9 MEMBER PETTI: Just a couple things, 10 notes. I saw typos. It's computational fluid 11 dynamics, not mechanics.
12 MEMBER PALMTAG: It was late.
13 MEMBER PETTI: Yeah, I think it was. And 14 then, when you talk about the riser holes, it makes it 15 sound like it was something done in the report. In 16 the latest TR, NuScale addressed this concern. Just 17 strike in the latest TR. They changed the design is 18 what -- right? I mean, it has nothing to do with the 19 topic.
20 And then I just thought that it could be 21 strengthened when you talk about the CFD stuff that 22 the staff did the calculations.
Additional 23 conservatism could mean a lot of different things to 24 a lot of people. I would actually put what their peak 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
44 number was because it's a significant additional 1
concern. I mean it demonstrates --
2 CHAIR KIRCHNER: You say on the order of 3
4 MEMBER PETTI: Oh, yeah, right.
5 CHAIR KIRCHNER: On the order of 100 ppm.
6 MEMBER PETTI: Well, it was 188 ppm, so I 7
mean that's a significant difference from the 28 ppm.
8 VICE CHAIR HALNON: So none of these 9
numbers are proprietary. These numbers are not 10 proprietary.
11 MEMBER PETTI: That's a staff calculation 12 (Simultaneous speaking.)
13 VICE CHAIR HALNON: Because the closed 14 session, we went through some of these numbers.
15 MEMBER PALMTAG: That was one example.
16 I'm just concerned. Was it one example, or is that a 17 typical number?
18 MEMBER PETTI: Well, let me just tell you 19 my sense. We raised this the last time. The 20 assumption that they used about, you know, two volumes 21 22 MEMBER PALMTAG: And I agree. I just --
23 I'm trying to quote it. I don't know how to quote a 24 number, or you know, is that a typical number, 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 average? You know, is that a --
1 (Simultaneous speaking.)
2 MEMBER PALMTAG: It's just one number.
3 MEMBER PETTI: I understand that, but I 4
asked specifically. It is what made the staff decide 5
everything is okay. That's why I asked the question.
6 MEMBER PALMTAG: So we could say something 7
on the order of 180?
8 MEMBER PETTI: Yeah, that's on the order 9
of. Yeah, that's fine.
10 MEMBER BALLINGER: This is Ron Ballinger.
11 We had some discussion last night and this morning, 12 and I sent a little note to Member Palmtag.
13 I think we're basically comparing apples 14 and oranges here, and we have to be careful about 15 that, in that those, for lack of a better word, the 16 smaller number that which where the pinch point is.
17 That's resulting from almost a stylized calculation, 18 a sense where you build in all kinds of uncertainty.
19 And for that kind of calculation, from my perspective, 20 if they come within 1 ppm, I don't care, because it's 21 a stylized calculation.
22 On the other hand, the CFD calculation, 23 that's more a best estimate calculation, which is to 24 me more realistic. And as long as they quote 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
46 uncertainties on that, then if that defines the 1
margin, then they're good. But the stylized 2
calculation is a little bit -- can be a little bit 3
misleading, especially at the public, when the numbers 4
come out very close to being what the public might say 5
is, well, hell, 20p or 30 or whatever the number is, 6
why not make it 50? Why not make it 100? But it's a 7
stylized calculation. So that's the thing that 8
concerned me. And I think there's an opportunity here 9
to make that kind of a statement as a precedent. See 10 what I'm trying to get at?
11 I don't know whether that is -- whether 12 you consider the smaller number calculation, for lack 13 of a better word, a stylized calculation. But we do 14 that all the time. And as long as -- if it's a 15 stylized calculation, if you're within 1, you're okay.
16 MEMBER PALMTAG: I'm not sure what that 17 means. What is stylized? I mean, there should be a 18 calculation and then --
19 (Simultaneous speaking.)
20 MEMBER BALLINGER: Remember, I'm a 21 metallurgist, all right?
22 MEMBER PETTI: Yeah, you're a reactor 23 physicist. So just understand the difference here is 24 like --
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47 MEMBER PALMTAG: I try to understand.
1 (Simultaneous speaking.)
2 MEMBER BALLINGER: We do appendix k. All 3
right, 2200. We do a calculation, and it's a stylized 4
calculation. This is how you do it. This is what you 5
do. You come out with a number. If it's less than 6
2200, you go home free. But a best estimate 7
calculation shows that you've got a thousand degrees 8
of margin. So we ought to think about asking people 9
to quote both. If you're going to do the stylized 10 plus the best estimate, you ought to make sure that 11 people know that it is a stylized calculation and that 12 that number that they came up with using the stylized 13 calculation is wrong. But it's a conservative, 14 stylized calculation.
15 MEMBER PETTI: Yeah. I think that was --
16 MEMBER BALLINGER: So I don't know whether 17 this earlier calculation is what we would call, in 18 other words, unenforced. You do it this way and you 19 incorporate this uncertainty in this calculation.
20 MEMBER PALMTAG: I think I agree with you.
21 What I was trying to say is maybe what I was trying to 22
-- I think what I was trying to say was, you know, 23 instead of saying a stylized calculation, let's 24 actually unroll some of those uncertainties and say, 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
48 you know, and say these are the uncertainties. And 1
instead of just saying, oh, we have lots of 2
uncertainty. Right. Oh, I don't know what that --
3 you know, is that 20? Is that 50? Is that a 4
thousand? I don't know. So I'd like to see some 5
quantification of the uncertainty. So it's kind of 6
stylized.
7 MEMBER BALLINGER: Yeah. I'm just 8
thinking that we need to make a distinction between --
9 I'm not -- don't use the word stylized, whatever it 10 is, pounding on the conservatism and the real, the 11 real deal.
12 MEMBER PALMTAG: Yes.
13 MEMBER BALLINGER: Because the real deal 14 in this case is large.
15 MEMBER PALMTAG: I thought that's what I 16 was trying to do, but maybe -
17 MEMBER BALLINGER: I think you did.
18 MEMBER PALMTAG: Yeah, okay.
19 MEMBER BIER: If I can butt in, I want to 20 make one minor point which is I do think we probably 21 need to have a proprietary check even for the results 22 of staff calculations because the inputs to those 23 calculations may be proprietary even if the 24 calculation is not.
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49 VICE CHAIR HALNON: At this point, what's 1
there is too late.
2 (Simultaneous speaking.)
3 MEMBER BIER: Oh, okay. Right. Thank 4
you.
5 MEMBER PALMTAG: Maybe what Dave had said 6
at the end.
7 (Laughter.)
8 VICE CHAIR HALNON: The reason I brought 9
it up is that we went through some of these numbers in 10 the closed session.
11 MEMBER BIER: Okay.
12 MEMBER PALMTAG: That's a good point, 13 yeah.
14 CHAIR KIRCHNER: Well, maybe to help the 15 discussion a little. This, what was reviewed here is 16 a methodology that they're going to use for licensing 17
- purposes, right?
So this is an evaluation 18 methodology. If the staff accepts it, that's not a 19 stylized calculation anymore. It's their EM model for 20 purposes of licensing.
21 So what staff went on to do is kind of 22 more in the, like you said, best estimate because they 23 used computational fluid dynamics to kind of get an 24 estimate on the recirculation and the downcomer 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
50 what the boron distribution might be and, hence, what 1
boron is going in the RRV. And that gives confidence 2
that they should have sufficient shutdown margin to 3
mean subcriticality.
4 I think what would have been useful is to, 5
where there are conservatisms in the application of 6
the methodology, to the extent that one could estimate 7
them in terms of PPM equivalent boron, that would --
8 that might help when we look at the results and see 9
that that pinch point that we talked about looks to be 10 a little tight versus, you know, what typically is 11 used in PWRs to satisfy oneself that you've got 12 sufficient shutdown margin. So maybe we ask for that 13 in the writeup, or it would help in certainly in the 14 public forum of making the safety case.
15 MEMBER BALLINGER: The one thing that the 16 CFD calculation results didn't include was the 17 uncertainty on those calculations.
18 CHAIR KIRCHNER: Yeah, that's true.
19 MEMBER BALLINGER: I mean CFD is a black 20 art as well as metallurgy.
21 CHAIR KIRCHNER: Yeah.
22 MEMBER PETTI: Except there is an equation 23 that they had to try to solve.
24 MEMBER BALLINGER: Say again?
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51 CHAIR KIRCHNER: Have your stokes.
1 MEMBER PETTI: Solved all of your stokes.
2 Metallurgy is --
3 (Laughter.)
4 MEMBER BALLINGER: Yeah, you're right.
5 MEMBER PALMTAG: Equation with a lot of 6
closures.
7 MEMBER PETTI: Without closure.
8 MEMBER BALLINGER: When you have six 9
adjustable parameters, I'm sorry, it's still a black 10 art. I agree.
11 MEMBER PALMTAG: It's the closures that 12 are black art.
13 CHAIR KIRCHNER: May I ask a question of 14 NuScale for clarification?
15 MEMBER PALMTAG: Yes, I'll be -- yeah.
16 Before -- one thing, I'll make a comment. Both of you 17 brought this up. This is the pinch point. That 18 actually gets a little complicated with GDC 27 because 19 that could be considered a short-term return to 20 criticality, which historically has been allowed. I 21 specifically stayed away from the pinch point. I'm 22 personally more concerned about the endpoint of the 23 long-term criticality. But I just wanted to bring 24 that up because I didn't mention pinch point 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
52 specifically.
1 CHAIR KIRCHNER: I just wanted to ask 2
NuScale if someone could answer this. The way the 3
writeup is right now, we talk about holes at the 4
midplane of the riser, but can you address in an open 5
session, can you address how many holes you have in 6
that riser section? I think I don't want to 7
speculate. I think I know the answer, but Megan, 8
perhaps? Or we have reserved the opportunity to go to 9
a closed session this morning if we need it as well.
10 PARTICIPANT: We'd have to clear the room.
11 (Simultaneous speaking.)
12 MS. MCCLOSKEY: Yeah, they --
13 CHAIR KIRCHNER: If you just stand here, 14 yep, thank you.
15 MS. MCCLOSKEY: Megan McCloskey, NuScale.
16 And if the if you're saying that the --
17 CHAIR KIRCHNER: You have holes, more 18 holes than just the midplane.
19 MS. MCCLOSKEY: Yes. And I think I would 20 clarify that the riser holes in the steam generator 21 region are near and above the midplane. And but the 22 riser holes that are important for the ECCS operation 23 are those in the lower riser region. We've got four 24 of those distributed around the riser.
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53 CHAIR KIRCHNER: Whereas the holes in the 1
midplane were just, I think, the DCA design. So I 2
didn't want to -- can you scroll up, Sandra? Yeah.
3 So the -- I think, thank you, Megan, first 4
of all. Thank you.
5 So, since NuScale volunteered that 6
information to clarify things, there are holes down at 7
the lower part of the riser that are pretty important 8
for the ECCS operation and preventing and 9
recirculating boron from the riser.
10 MEMBER PALMTAG: So, on line 86 I say 11 additional riser holes at the midplane level.
12 CHAIR KIRCHNER: Yeah, that was the DCA 13 design. This design has holes at the top. So, as 14 soon as the riser is uncovered, they will still have 15 boron circulation into the downcomer as the levels 16 drop. There are holes then at the bottom of the riser 17 that are the really critical ones for the long-term 18 situation.
19 MEMBER PALMTAG: Take out at the midpoint 20 level?
21 CHAIR KIRCHNER: Yeah. I think you could 22 just say additional riser holes.
23 MEMBER PALMTAG: Yeah, okay.
24 MEMBER PETTI: It's below the midplane 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
54 level.
1 CHAIR KIRCHNER: That's really important 2
in the long term.
3 MEMBER PETTI: No, he said at, so I think 4
both --
5 MEMBER PALMTAG: Right. I'll just take 6
that out, so I'll just take out at the midplane.
7 MR. SNODDERLY: In defense of Member 8
Palmtag, the proprietary feedback that we got from --
9 we're getting into that area, so I think --
10 CHAIR KIRCHNER: Yeah. I know, but --
11 MR. SNODDERLY: So it's better to just 12 keep it generic and just say --
13 CHAIR KIRCHNER: With NuScale's input 14 though, I think we can just keep it generic.
15 MEMBER PALMTAG: Yeah, we'd make this --
16 CHAIR KIRCHNER: Additional riser holes, 17 but the key ones for long-term cooling are going to be 18 those that are lower down.
19 MR. SNODDERLY: But I think we can make 20 the changes now.
21 CHAIR KIRCHNER: Yeah.
22 MR. SNODDERLY: Got NuScale. I'd 23 recommend trying to take --
24 CHAIR KIRCHNER: Yeah, let's see if we can 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
55 fix it now.
1 MR. SNODDERLY: So, Scott, you can -- you 2
can make -- have -- direct Sandra to make the changes.
3 MEMBER PALMTAG: Want me to go through all 4
the changes?
5 MEMBER PETTI: Sure.
6 MR. SNODDERLY: At least the major ones, 7
you know, while it's fresh in your -- I mean you've 8
got --
9 CHAIR KIRCHNER: Yeah. Let's do it in 10 real time.
11 MEMBER PALMTAG: On the first paragraph, 12 last sentence of the first paragraph, I think it was 13
-- I've had G -- there's a GCD in there, should be all 14 GDCs. Subcritical, the numbered values that was one 15 in the coolant, at 33, RCS coolant. Yes. Yeah.
16 Search for CFD, then a mechanic before that. It 17 should be dynamics. Section -- if you go down to 18 section riser holes, line 85 in the latest TR, in the 19 latest design. Dave brought that up. Actually, let's 20 be more specific. In the US460 design, not latest, so 21 just say in the US460 design. Addressed Dave's 22 comment.
23 MEMBER PETTI: Oh, now you've got it in 24 two places. I'd just get rid of that phrase. Just 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
56 say starting --
1 MEMBER PALMTAG: You should take out in 2
the US460 design.
3 Line 86, remove at the midplane level 4
additional riser holes, take out of the steam 5
generators, and now I had a spelling mistake on this 6
and influx. Line 87, take out this.
7 MEMBER HARRINGTON: And Scott, right 8
there, the next line, you've got boron baskets, and 9
you do that again later. I would put ESP. You've 10 already defined that, and it's more specific than just 11 boron baskets.
12 MEMBER PALMTAG: Line 88, boron, change 13 boron baskets to ECB --
14 MEMBER PETTI: ESP.
15 MEMBER PALMTAG: ESP.
16 CHAIR KIRCHNER: Is that defined above?
17 MEMBER PALMTAG: Yes. So that should be 18 last paragraph an ESP subscript -- it needs an article 19 or something or the.
20 MEMBER ROBERTS: We already added this 21 time. Go back up to the second paragraph.
22 MEMBER PALMTAG: I mean the ESP system or 23 something like that.
24 MEMBER ROBERTS: Yeah. Line 17, the TR is 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
57 methodology, something like calculation using the TR 1
methodology for the beginning of that sentence 2
starting the TR. You know what I'm saying?
3 MEMBER PALMTAG: Seventeen, it says the 4
TR.
5 MEMBER ROBERTS: Calculation using the TR 6
methodology.
7 MEMBER PETTI: Calculations in the chat?
8 CHAIR KIRCHNER: Calculations show.
9 MEMBER PALMTAG: Show, yeah, take out the 10 S on shows, shows to show.
11 CHAIR KIRCHNER: Calculations in 17 show.
12 MEMBER BIER: Yeah, it should either be 13 calculations show, or calculation shows, so whichever 14 way.
15 MEMBER PALMTAG:
On 17, change 16 calculations to -- or add an S to calculation.
17 MEMBER PETTI: Scott, in your conclusions, 18 the first conclusion is actually two separate 19 conclusions. I would maybe break them up, the last 20 sentence is the first.
21 MEMBER PALMTAG: So this is real-time. We 22 could do it. They shouldn't be conclusions. They 23 should just be facts.
24 MEMBER PETTI: Yeah. I'm not worried 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
58 about that. We have a lot of flexibility this stuff.
1 But to me, since it's two separate --
2 MEMBER PALMTAG: How would you break it 3
into --
4 MEMBER PETTI: The last sentence, just 5
make it its own item.
6 MEMBER PALMTAG: Yeah. No, the last 7
sentence, you're actually right. Make that number 8
two, and then --
9 MEMBER PETTI: I would -- if it were up to 10 me, I would also put the third one first.
11 MEMBER PALMTAG: Okay. If we do that, we 12 should change the sections text, too. I talked about 13 the --
14 MEMBER PETTI: Oh, you -- oh then, we made 15 it.
16 VICE CHAIR HALNON: We need to -- this is 17 letter writing.
18 MEMBER PALMTAG: Yeah, I know.
19 MEMBER PETTI: Yeah.
20 CHAIR KIRCHNER: Yeah.
21 VICE CHAIR HALNON: And then we're not 22 writing a letter on this. So we need to now take the 23 comments.
24 CHAIR KIRCHNER: We need to take stock 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
59 where we are.
1 VICE CHAIR HALNON: Yeah, take your 2
comments and provide them the -- about the Chapter 15 3
memo, or you convert this into a letter and schedule 4
it appropriately.
5 CHAIR KIRCHNER: So what -- we are at a 6
juncture where we have now made some significant 7
conclusions, and I think recommendations. So, now, we 8
as a committee need to decide whether we should 9
convert this into a letter.
10 And this was one of the major concerns 11 coming out of the DCA review. And my sense is that 12 this is worthy of a short letter report at this point.
13 Just to reflect on the DCA review, we 14 wrote quite a few letter reports at significant 15 junctures in that review. Given the importance of 16 this and the amount of redesign and work that went 17 into this by both the applicant, primarily by the 18 applicant, and then the review by the staff, they have 19 an SER. Are we in a situation here where we ought to 20 recommend that they issue the SER and not delay this 21 for another month or two? So I ask you as a committee 22 to think where we are.
23 And this goes beyond, and Bob, in the 24 previous
- memo, pointed out perhaps an undue 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
60 conservatism that the staff was adding to an L&C on a 1
TR, but this was a major design issue for the NuScale, 2
you know, TCA, and considerable rework and design has 3
been undertaken by the applicant to address this. And 4
here we have things that, in my opinion, rise above 5
the level of summary report. So should we convert 6
this? What I'm asking you to consider, should we 7
convert this to a short letter report?
8 MEMBER PETTI: So the thing that that 9
isn't here is that this makes the design safer.
10 CHAIR KIRCHNER: Yes. Well, and that's --
11 MEMBER PETTI: I mean, that doesn't jump 12 out at you in the letter, and I --
13 CHAIR KIRCHNER: And it wouldn't jump out.
14 MEMBER PETTI: And again, this is --
15 again, this is not -- this is the methodology of the 16 topical report.
17 CHAIR KIRCHNER: Yeah.
18 MEMBER PETTI: And that, you know, first 19 bullet there is much more of a design issue that we 20 would probably say in the final letter.
21 CHAIR KIRCHNER: We would.
22 MEMBER PETTI: For sure.
23 CHAIR KIRCHNER: We would repeat it.
24 MEMBER PETTI: Right. But I think it's 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
61 important. I'm -- yeah, I'm a little worried about 1
sort of the tone, for lack of a better word, but the 2
context, you know, is how do we structure the water 3
limit the way the -
4 MEMBER PALMTAG: I think we can add a 5
conclusion point that there wasn't an exception taken 6
to GDC 27, which makes it safer design. I think 7
that's -- that'd be an important conclusion.
8 MEMBER BALLINGER: If we convert this to 9
a letter, it's easy, and we then can just reference 10 the letter in the final, makes that easy as well.
11 CHAIR KIRCHNER: Any thoughts? Tom?
12 MEMBER ROBERTS: It seems about worthy of 13 a letter to me. The question is timing that by the 14 time we get this letter out, the NuScale letter might 15 also be out at the same time. In which case, Scott's 16 original idea was to roll these up into the NuScale 17 letter. So I'm not sure how the timing works.
18 MEMBER BALLINGER: Is it such that this is 19 in good enough shape so that with minor -- we could 20 probably make it as long as we want. But can we just 21 do this letter right now?
22 MEMBER PETTI: It's on the AWS to be done 23 this meeting.
24 MEMBER BALLINGER: Yes.
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62 MEMBER HARRINGTON: I'll also note it may 1
not be adequate, but it is also talked about in the 2
Chapter 6 memo but might be between the binders. I 3
don't know. What do you think, Greg, should we --
4 VICE CHAIR HALNON: So what I would do 5
recommend is that we take what we have here. To Ron's 6
point, let's just turn it into a letter. We'll do 7
that Friday morning and finish it and do the other 8
business that we have to do and just kind of move on 9
in this meeting. But let's make sure Scott has all 10 the comments. We don't need detailed edits now. We 11 could do those on Friday morning. It should not take 12 too long because we've already done some of the edits, 13 and I could -- you, Scott, can just turn it into 14 letter format, and we'll go from there.
15 I mean because a lot of the letters could 16 be boilerplate like we normally do. It cites a 17 previous letter report already that we need to -- we 18 can reference back to. So you don't have to put a lot 19 of detail in from that other letter report. You just 20 have to summarize what we did.
21 So, to me, it's 80 percent, if not more, 22 there, and we can still finish it. We got time, and 23 then we've got to at least one maybe difficult letter 24 ahead of us. But other than that, we should be free.
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63 CHAIR KIRCHNER: Yeah, if we can get it 1
done Friday, then we could go ahead. Otherwise, the 2
alternative is we just make it a major part of the 3
final letter in May.
4 MEMBER PETTI: What I'm worried about 5
because I've now done this two or three times, this is 6
the topical report. What we heard yesterday was 7
Chapter 15. And in my mind, I've got conflating --
8 I'm conflating them. And frankly, that first bullet 9
is really a design issue that maybe fits better in 10 Chapter 15.
11 CHAIR KIRCHNER: Oh, that's the problem.
12 MEMBER PETTI: Yeah, that's the concern.
13 So the scope here, that's, that's more Chapter 15, but 14 like --
15 CHAIR KIRCHNER: We've got a lot of 16 Chapter 15 and design in this.
17 MEMBER PETTI: And if you just took that 18 out and saved it for Chapter 15, then you have to ask 19 yourself, do we really need a letter report on the 20 methodology, per se?
21 VICE CHAIR HALNON: If you reduce this, 22 what we have here, just down to methodology, then 23 you're fine. Just do a paragraph on the summary of 24 the methodology and you can make a point, a point or 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
64 two in the Chapter 15 memo saying application of this 1
methodology leads us to some concerns that will be 2
discussed in the Chapter 15 memo. And then you can 3
start putting this detail.
4 MEMBER PETTI: That may be cleaner and 5
quicker.
6 VICE CHAIR HALNON: So that, and that 7
works too. I mean, the key is, is that you don't want 8
to -- I mean, this can't -- you can't leave this as a 9
summary. I think we all agree with that, right?
10 MEMBER PETTI: No, no. I --
11 VICE CHAIR HALNON: I mean, it's too 12 detailed to leave it the way it is. So we need to 13 take that and stick it into an official memo, so --
14 MEMBER PETTI: No, no. I'm thinking if 15 you, if you focus it purely on the TR, you take out 16 any of the design stuff, then it would be a summary.
17 VICE CHAIR HALNON: Yeah, it should be a 18 paragraph. It should be a paragraph or two on the TR 19 itself. But take this concern about the root 20 criticality and stick that in the 15 with the other 21 things that they added. Does that make sense, Scott?
22 Can you reduce this down to just a methodology 23 discussion and then just point to the 15 memo and give 24 that information to Bob?
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65 MEMBER PALMTAG: What do you want to 1
remove? One or two?
2 MEMBER PETTI: No, we --
3 MEMBER PALMTAG: Is there any reason to --
4 MR. SNODDERLY: It may be helpful to go to 5
the final letter outline now. I think that will help 6
inform you, but you won't put it there. And then I 7
can work with Scott to take this back up a level to be 8
just a pure -- the SER should be issued for the 9
topical report. And then you, you know, you can refer 10 to the Chapter 15 memo with the final letter.
11 We got -- I think it would be valuable for 12 the Committee to take the next two hours to start 13 talking about the final letter and what you want in 14 that and that will help inform you as to what level of 15 detail you want to put in this and whether it should 16 be a letter or something.
17 MEMBER PETTI: I think the additional 18 riser hole paragraph and the conclusion associated 19 with it is a design issue, the Chapter 15 issue.
20 MEMBER PALMTAG: So take out the riser --
21 MEMBER PETTI: Take that, and then it's 22 two pages. It's fine.
23 MR.
BURKHART:
- Yeah, this is Larry 24 Burkhart. Chairman, if I could ask, if we could 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
66 the staff just a chance to reiterate. I think you're 1
on the right path to reiterate the scope of the 2
topical report versus the SDAA. So, I've got Becky 3
Patton.
4 MS. PATTON: Sorry, this is Becky Patton.
5 Yeah, the second one also, if it has like a tech spec 6
on a recommendation in it, that one would also be a 7
Chapter 15. Remember there's a section 1505 that 8
implements the XPC methodology that's actually in 9
Chapter 15 and reviews those calculations. So 10 anything that would be some change that should be 11 made, you know, for the SDA would be a recommendation 12 on the SDA itself, in addition to the discussion on 13 holes.
14 MEMBER PALMTAG: So it sounds like both --
15 everything needs to be taken out. That's where what's 16 left.
17 CHAIR KIRCHNER: Well, this is how it 18 often happens with the TRs. They have a lengthy 19 appendix, or I guess as an example calculations --
20 MEMBER PALMTAG: The last line --
21 CHAIR KIRCHNER: -- methodology is 22 applied, and it's then incorporated, either the 23 methodology or -- and/or the calculations are --
24 MEMBER PALMTAG: So if you go down 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
67 last line --
1 (Simultaneous speaking.)
2 CHAIR KIRCHNER: -- in 15.
3 MEMBER PALMTAG: The last line, is there 4
any reason to take anything out, or is this just all 5
going to the 15?
6 Sandra, you can scroll down the last line.
7 This going to be -- can we just roll this up and leave 8
it and roll it up, or we can take out the riser hole?
9 I'm just -- I'm not sure what you're asking for to 10 take out and leave in.
11 VICE CHAIR HALNON:
I'm
- thinking, 12 personally, that it's just a short paragraph saying 13 the EM is adequate for consideration. You can find 14 what the right words are, and then take your 15 information in here, both recommendations, and roll it 16 up into the 15 memo.
17 I'm having trouble making recommendations 18 in a summary, and because it doesn't it just -- it 19 should be a summary. It's just part. It's just 20 saying, hey, we're -- we did it. We're fine with it.
21 The design information in the tech spec 22 recommendations for tech spec needs to go into either 23 the memo and then I think that's that last thing --
24 actually, we'll deliberate it in final letter, which 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
68 goes to the Commission.
1 So my sense is if you can distill this 2
down to just address the methodology, the TR, and then 3
make the statement saying use of this methodology --
4 say Chapter 15 or design, however you want to say it.
5 You can point to the Chapter 15 memo saying 6
recommendations contained in Chapter 15. So there's 7
half people can go from the summary to Chapter 15 8
memo. They can go from the Chapter 15 memo if 9
necessary to find all that. They all stand on their 10 own. That would be my thought.
11 So this reduces it down to just what the 12 methodology talks about which in my mind was TR 13 application to the TR and how it's used gets into 14 Chapter 15. So all the words are great. It's just 15 not where they park.
16 Chapter 15 memo, when is that, like next 17 meeting? May? To the May meeting?
18 CHAIR KIRCHNER: Yeah, it is in the May 19 meeting.
20 VICE CHAIR HALNON: Okay. So that'll give 21 you some time.
22 CHAIR KIRCHNER: One for 15 in the May 23 meeting, but you know, by then, we're into the final 24 letter report.
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
69 VICE CHAIR HALNON: When is the final 1
letter report due?
2 CHAIR KIRCHNER: May.
3 (Simultaneous speaking.)
4 MEMBER PETTI: I think it's even more than 5
that. As I'm looking through, I see lots of snippets 6
of Chapter 15 in here. I think you're going to have 7
to cut out even more.
8 MEMBER PALMTAG: No, I agree. I'm just 9
trying to look for some guidance on where the pieces 10 go.
11 MEMBER PETTI: Again, don't throw this 12 away. This is a good letter for 15 stuff, but I'd 13 keep this summary as short and sweet as you could.
14 MEMBER PALMTAG: Now, where are we landing 15 on a letter specific related to boron and maybe --
16 VICE CHAIR HALNON: No, we're landing in 17 the paragraph on the methodology, saying that it's 18 fine. And then take the rest of this Chapter 15 stuff 19 and add it to you, and then you just maintain the two 20 recommendations.
21 MEMBER ROBERTS: But as for a separate 22 letter just focusing on the big issue, we've moved 23 away from that at this point.
24 VICE CHAIR HALNON: That's a Chapter 15 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
70 still. That's behind us basically.
1 MEMBER ROBERTS: Sure.
2 VICE CHAIR HALNON: It's all -- it's not 3
a concern now. It's behind us. We don't want to make 4
5 MEMBER ROBERTS: Okay, but you've got to 6
7 VICE CHAIR HALNON: We don't want to 8
re-adjudicate that whole issue in this letter.
9 MEMBER ROBERTS: But the tech spec 10 recommendation is new, so we want to make sure we 11 highlight
- that, and that'll be probably a
12 recommendation in the final a letter if we all agree 13 it's important.
14 Did that help, Scott? I mean, is it --
15 you still, like, willing to do over --
16 (Laughter.)
17 MEMBER PALMTAG: I'll figure it out, yeah.
18 I think it'll make more sense after we get through 19 today, yeah.
20 VICE CHAIR HALNON: Yeah, this process is 21 just process. We can talk more later. You got all 22 the substances there. It's just a matter of just only 23 24 MEMBER PETTI:
Just focus on 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
71 methodology, not on its application. That makes it 1
really short, I think.
2 MEMBER ROBERTS: Maybe I'll clarify. We 3
talked about a standalone letter because it's so 4
important. I think we've concluded no, that the 5
standalone letter will be incorporated into the big 6
chapter -- or big NuScale letter. And Bob's Chapter 7
15 memo will tee up the issues that are currently up 8
on the screen here because they're more Germane to 9
Chapter 15 than they are to the topical report. But 10 the letter will be in the big NuScale letter.
11 CHAIR KIRCHNER: Right.
12 MEMBER ROBERTS: Okay. That's my --
13 thanks.
14 CHAIR KIRCHNER: Just from a practical 15 standpoint, and we're so close to the end now that we 16 ought to save what Scott has highlighted here and what 17 Bob will address in his Chapter 15 memo, extract that, 18 put it into the final letter.
19 So, at this point, Scott, I think the 20 consensus is just shorten this, save, don't throw 21 anything away, but save it, and shorten this writeup 22 just to the methodology, if you can find a way to do 23 that. And we'll take that up on P&P. But then we'll 24 take a break here, come back, and discuss an outline 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
72 for the final letter report after the break and maybe 1
that will help provide some clarity as to how we're 2
going to pick up these pieces.
3 MEMBER MARTIN: You say final letter.
4 Final NuScale letter or chapter letter?
5 CHAIR KIRCHNER: Final NuScale letter, 6
yeah.
7 MEMBER ROBERTS: Yeah, and Walt, just the 8
details cover for this morning. We also wanted to 9
talk about EDAS just to close the loop between the 10 staff and the applicant after last night. We do that 11 now or after the outline?
12 MR. SNODDERLY: It's in the outline.
13 CHAIR KIRCHNER: In the outline. Let's 14 talk about it during the outline.
15 MEMBER ROBERTS: Okay. Great. Thank you.
16 CHAIR KIRCHNER: With one caution, we 17 don't have to resolve the staff. We're not going to 18 be an intermediary between the staff and the applicant 19 on EDAS. We will have our own committee opinion on 20 the matter.
21 VICE CHAIR HALNON: And I just have a few 22 questions that I want to pose to the staff to make 23 sure that we were briefed on or at least some feedback 24 and has to do with some definitions and stuff. So 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
73 there's just a -- I just didn't want to -- yesterday, 1
I made the comment because I didn't want to leave it 2
hanging where staff said one thing, management's 3
working on it. NuScale came up and said we totally 4
disagree. You know, not totally, that's probably 5
experience, but we disagree because of this. And we 6
just went on to the next thing. I just wanted to make 7
sure we have some closure on the pressure, at least 8
from a committee perspective.
9 CHAIR KIRCHNER: We don't want the 10 Committee to be in the middle of a differing press 11 professional --
12 VICE CHAIR HALNON: Right. Not here --
13 CHAIR KIRCHNER: We're not here to 14 adjudicate those kind of things. We are here to 15 provide our assessment on EDAS.
16 MEMBER ROBERTS: Right. To the extent we 17 make sure we understand the argument.
18 CHAIR KIRCHNER: Right. We have to 19 understand the arguments. Yes. Okay, let's take a 20 break. And my glasses aren't good enough to see what 21 time -- 10:06. Let's come back at 10:20. Okay. We 22 are recessed.
23 (Whereupon, the above-entitled matter went 24 off the record at 10:06 a.m. and resumed at 10:24 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
74 a.m.)
1 CHAIR KIRCHNER: Okay. Back in session.
2 And we're going to go onto a discussion and we're not 3
going to read this line by line, but what we have is 4
kind of a draft, or what the final letter may look 5
like. And we're, the discussion today should be more 6
about, the content is, not necessarily the conclusion 7
and recommendations.
8 So, we're not putting out conclusions and 9
recommendations, or rather an outline. We're in 10 discussion about what material we want to incorporate.
11 So, starting at the top, acronyms, to take this back 12 to the US 60 -- 600 design and our letter work back in 13 July of 2020.
14 Obviously, things that I think we need to 15 highlight again from that exercise, could you scroll 16 down? Thank you. Is that for the DCA what we focused 17 on were five cross-cutting areas. You heard a little 18 bit more again today about ECCS valve performance.
19 The other big issue was, at the time, was the DWO and 20 the helical tube steam generator design.
21 We were just discussing the Boron 22 dilution, return to criticality issue. I think the 23 source term, seems it has pretty much gone away as an 24 issue because of design changes. And then we 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
75 commented on the completeness of the PRA. We also had 1
some other points in there.
2 My thinking is in Ting this up, we'll 3
quickly summarize where we were coming out of the DCA 4
review, five years ago. And then talk about, scroll 5
down a little further if you would, Sandra. Discuss 6
the -- and scroll down even a little bit further. I, 7
we just had a discussion about ECCS valves.
8 Okay. So, I'm going to look here also, to 9
making assignments if I could. So, a little bit 10 further up, the other way. So, yes. There are, there 11 it is, okay. So, I would look to Bob and Craig to 12 provide a write-up on the steam generator design and 13 the DWO issue. I don't want to repeat here in real 14 time what the Applicant has done. But I'm looking to 15 you two. We would have a section on that particular 16 matter.
17 We just were discussing, you can see, we 18 had a conflated discussion in methodology in Chapter 19 15 on Boron dilution, return to criticality. Section 20 on that, then Dave, oh, sorry. So that would be a 21 combination of Scott and Bob on the Boron dilution and 22 any other highlights that you think are important from 23 the Chapter 15 review.
24 Then on the source term, they made some 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
76 design changes. So, Dave could you, you know, revisit 1
what we did there on source term and the problems that 2
we identified during the DCA review, pretty much had 3
been eliminated. So, just the, an assessment of the 4
design changes and how you see that impacting.
5 MEMBER PETTI: Well, let me be a negative 6
Nelly here.
7 CHAIR KIRCHNER: Yeah.
8 MEMBER PETTI: I don't like this online.
9 MEMBER BALLINGER: Tell us how you really 10 feel.
11 (Laughter.)
12 MEMBER PETTI: Okay. I don't like this 13 online. We did talk.
14 CHAIR KIRCHNER: Yeah.
15 MEMBER PETTI: This is so transactional, 16 and it's, oh, that's what we did before and now how, 17 here's what we did now. And here's what we did -- but 18 it misses the big picture. You know when we write, 19 we've written letters for some of the other advanced 20 reactors, we start with a paragraph of what that 21 reactor is and what its characteristics are. No where 22 do we talk about that this is a fully passive plant, 23 and what does that really mean?
24 I'm thinking about strong positive 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
77 statements of the design in that light. I mean these 1
guys are the first ones of, on large LWRs, they are 2
LDR, not LWRs, large LDRs that have taken it all the 3
way. You know, it's not just the marketing which we, 4
you know, we all know about. But they've actually 5
demonstrated some of these important characteristics 6
of how their safety functions are executed, you know, 7
automatically, without reactor, without operator 8
intervention in a completely passive manner.
9 Similarly, if you look at the PRA, you 10 know, we love to get into all the weeds, but there's 11 a reason why their core damage frequency and their 12 LERF are low. We can argue the absolute magnitude of 13 the numbers, but if you just look, and read, and think 14 about the design. The double valving everywhere, I 15 mean there is also so stuff that reduces the 16 frequency.
17 That's the type of stuff that I think 18 you'd want to put in the letter to provide confidence 19 to the public about why this design has safety 20 features. Then I have no problem because now there 21 have been a number of specific changes that they've 22 made. And we can go through these and delineate all 23 these changes.
24 But up front, I think we need 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
78 that really addresses that big picture, you know. If 1
you look at the Kairos letter for instance, that's 2
what we did. And we used the safety functions to kind 3
of generate our thought process. Whether you actually 4
have to do that here or not, but --
5 CHAIR KIRCHNER: Well, I was thinking more 6
of introducing all these first, with the, not only the 7
deltas in the design, including the power upgrade, but 8
to actually put in a fairly detailed description of 9
the actual safety aspects of the design.
10 MEMBER PETTI: Okay. So, I mean, I guess 11 it's a question of whether to do it first or last?
12 CHAIR KIRCHNER: I would do it first.
13 MEMBER PETTI: Me too, I like to be lead 14 with the --
15 MEMBER DIMITRIJEVIC: Well, Dave, I mean 16 you talk like we are here advertising agency for 17 public. I mean, that's not, you know, we are sort of 18 like, you know, advisory committee in safety. So, I 19 think where we should concentrate, okay, while this 20 was great, they sit in this big pool and they just 21 have a valves. But that is still things which, you 22 know, should be kept eye on.
23 And, you know, things we don't have 24 experience with that, and, you know, the new staff.
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
79 And then relying on one thing and what can go wrong.
1 I mean why should we write this as, you know, really 2
as advertising.
3 MEMBER PETTI: It's not --
4 MEMBER DIMITRIJEVIC: Our job is to find 5
out, I mean to say what we thinking. They're just 6
relying on one thing, is that thing which can go wrong 7
with that. Is there something they missed, is that, 8
are they too optimistic in some areas? You know, 9
that's how I would see this letter.
10 MEMBER PETTI: My view is that there are 11 times when I sit at this table, and I keep thinking, 12 guys this is a bunch of molecules in a huge pool of 13 water. You seem to have forgotten that. You know, we 14 get down the rabbit holes. And I mean, that's just 15 what we do. But losing the forest through the trees.
16 And it's a balance. I'm not going to argue that it's 17 not.
18 But these are the first ones that have 19 gone all the way, done all the work. And they're 20 still not there, obviously. You know, we talked about 21 the valve testing and the like, this morning. But 22 there's a significant amount of investment that 23 somehow we should be able to make a statement about, 24 you know, there's a lot behind these. the statements 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
80 that are made.
1 You know, I mean, we said the same thing 2
on SHINE when we got there too, if you remember. We 3
were very complimentary because when they put all the 4
pieces together, it all hung together. And that was 5
a really different system than a reactor, right?
6 MEMBER PALMTAG: In terms of safety and 7
the like, you've got to remember there's three, at 8
least two or three more LWRs coming through here. So, 9
I do think it's important to emphasis how -- the 10 safety aspects of this and kind of set the bar high, 11 you know, when these other reactors to come through, 12 you know.
13 MEMBER DIMITRIJEVIC: Well, I mean the 14 advanced reactors before it shows that, you know, 10 15 to minus 12, you know, this boiling water reactors in 16 the CDF. I mean the question is really though, such 17 small numbers, I mean, you know. I really -- and if 18 we felt like this things, they are sitting in this 19 pool and there's nothing can go wrong, why did we 20 spend the time coming here? Coming and going over and 21 over talking about that? It's not how I, I don't, 22 that's not how I feel.
23 I mean, that's how, I feel like we should 24 really feel. Depending on one thing, it's our job 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
81 look in everything which can go wrong with that thing, 1
so.
2 VICE CHAIR HALNON: We have a generic 3
outline, Exhibit 9, in our guidance. And we should 4
follow that. We should discuss what Dave was talking 5
about, the novel aspects of this design as part of it.
6 You know, even if it was just a couple of sentences or 7
a paragraph that's part of the generic outline.
8 These issues that we have can still be 9
included, it's just a matter of where they are in that 10 outline. So, we should follow through. And I would 11 think that like maybe the staff should be able to take 12 the memos that's been written and just block copies on 13 the text instead of the final recommendations or 14 whatever and plug it into that template basically, the 15 outline. And then we start there and that would be 16 the letter, other than the first part of it. And I 17 was just pulling it up here.
18 It starts with the background. Section 2 19 is other novel and unique aspects of this design. And 20 there's some examples there. Relevant previous 21 operating experience, which is basically going to be 22 in the test loops and the other things that they've 23 done, just the highlight there. So, you're not 24 really, you're not advertising it. But you're 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
82 acknowledging the experience.
1 And then you talk about the principle 2
safety functions and that's where some of these things 3
would fall out. And then you can talk about safety.
4 I don't think that's as relevant here because it's 5
not, it's just a light water reactor.
6 And then in the summary, the key analysis 7
results. So, yea, I think you can take what we've 8
done here and stick it into that outline and have, you 9
know, like 50 percent there.
10 MEMBER PETTI: I'm more worried about, you 11
- know, we've highlighted that outline to the 12 Commissioners, and then if the NuScale letter doesn't 13 look like it, why did you treat them differently? You 14 know, that's the, it's an obvious thing.
15 CHAIR KIRCHNER: Yes, well that's the 16 other, but there's history and we --
17 (Simultaneous speaking.)
18 MEMBER PETTI: I understand that.
19 CHAIR KIRCHNER: It's open items from the 20 DCA.
21 MEMBER PETTI: And I definitely wouldn't 22 want to deal with those, you know.
23 VICE CHAIR HALNON: That's, that's fitting 24 it into the outline.
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83 MEMBER PETTI: Right, I think so, yes.
1 MR. SNODDERLY: But I think it's important 2
to acknowledge that significant issues existed as a 3
result of the DCA and the carve outs and some other 4
things.
5 CHAIR KIRCHNER: That's fine.
6 MR. SNODDERLY: And significant design 7
work, design changes that were made by the Applicant.
8 MEMBER PETTI: That makes the reactor much 9
10 (Simultaneous speaking.)
11 VICE CHAIR HALNON: Yes, so, and in 12 Section 2 and 3, it's 2 is the other novel and unique 13 aspects. So, you could say, you know, that one of the 14 unique aspects is that this has been in front of us 15 before and they fixed all the issues. Or you could do 16 it under relevant previous operating experience, which 17 is during the previous DCA review, they solved the 18 issues. So, there's a couple place it could fit and 19 not feel like it's out of place.
20 Well, I think Walt also didn't get a 21 chance to finish. I think you've got to finish making 22 a number of assignments.
23 CHAIR KIRCHNER: We did.
24 VICE CHAIR HALNON: For the areas that we 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
84 haven't bought in?
1 MEMBER PETTI: You need to scroll up a 2
little bit, you forgot ECCS, about performance.
3 MR. BURKHART: Yes, Chairman, a Member --
4 so Larry -- has his hand up.
5 CHAIR KIRCHNER: Yes, Matt, sorry I saw 6
your hand up earlier. Yes, go ahead.
7 MEMBER SUNSERI: That's okay, Walt, I 8
know. I must agree with Dave in one respect, I mean, 9
we need to step back and think about who our audience 10 is. It's not the general public. I know we write 11 these things so the public can understand them. It's 12 not the EDO. We're writing to the Commission, right?
13 And we're writing to Commission about something that 14 has gone on for a real long time. And it seems to me, 15 it discredits our charter obligation to speak on 16 matters of safety, in an unprescribed manner, all 17 right.
18 I've heard so many times in the last 19 couple weeks, especially on this NuScale review about 20 how this meets the regulation, or blah, blah, blah, 21 blah. Well, to be honest, we don't care about the 22 regulation, right. That's why the staff is there to 23 ensure the design meets the regulation.
24 We take a higher road. We look 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
85 integral effects. We look at big picture. We look at 1
things that are outside the bounds of regulation 2
because that's what Congress wanted us to do. They 3
wanted a second group to do an independent review, to 4
make sure that there's no holes in the regulation that 5
is allowing a safety signet to gain issue, to slip by, 6
it's going to get out into the, you know, be built.
7 So, to me, our letter, our final letters 8
are too long. They need to be more direct to the 9
point that the design is safe. I don't think we need 10 to go back in a whole chronology of blow-by-blow of 11 what happened over the last, you know, 17 months or 12 however long we've been reviewing this.
13 And it seems to me, like, that I just lost 14 my point. We need to think about this in the context 15 of the contemporary environment we're in, the ADVANCE 16 Act, you know. There's more reactors coming. You 17 know, we ought to frame this up in a way that says, 18 we've looked at this, we've learned some lessons.
19 It's safe. There's more coming, et cetera, et cetera.
20 And I think this is where Dave is trying 21 to take us with his remarks. Dave, am I speaking too 22 much for you, or?
23 MEMBER PETTI: No. I'm with you.
24 MEMBER SUNSERI: Anyway, that's just my 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
86 general input. And I don't have any specific 1
recommendations on how to change this.
2 CHAIR KIRCHNER: Dave, Members, further 3
input?
4 (No audible response.)
5 CHAIR KIRCHNER: So, I obviously have an 6
action. Greg is right, we have a template that we 7
adopted. I'll look at that again and see, with your 8
input, how to structure this. I wasn't of a mind to 9
rehash everything, Matt. I thought a short letter 10 would work. We can put all the background material in 11 appendices. It's there for the public record or 12 anyone who wants to test how thorough we were in terms 13 of our review.
14 My sense would be along the lines Dave 15 said, a pretty strong set of conclusions and 16 recommendations to the Commission. The Commission is 17 the audience and this sets a precedent in the fact 18 that this is probably, well not probably, this is in 19 my own personal assessment, this a very complete 20 application. We've been through it effectively, 21 twice.
22 And I don't know that we're going to see 23 this level of detail from the other applicants, to be 24 candid. And so, my own personal assessment is 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
87 NuScale went away from the DCA review, they made 1
significant design changes. They've addressed the 2
issues that were identified.
3 Vesna, I don't feel like we're showing for 4
NuScale, but by making a positive statement, if we all 5
agree that this design is safe and meets the 6
requirements, that that's where I am right now. And 7
I don't see that's a letter anything like, as long as 8
what we did for the DCA.
9 MEMBER DIMITRIJEVIC: No, I mean, Walt, 10 that could be true. I just want to say from the point 11 of view, that sitting in big pool of water with, you 12 know, just like for valves to open or rotate. But 13 that was true in the DCA and still we found many 14 concerns. That's no guarantee. I mean, we still have 15 to look into stuff, when we were coming here. And, 16 you know, and that's what we should just like make 17 clear.
18 That now, that we, I mean I liked Scott's 19 letter this morning very much because, he went all of 20 these modern concerns. And, you know, sometimes you 21 feel like 100 percent they have been addressed. And 22 sometimes you think they have been addressed. I mean, 23 the thing is like, you know, that we -- this is the 24 same design as it was in that, when this, you know, 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
88 ECCS, the changes.
1 So, I mean, you know, we have to look 2
through them, and make conclude that these problems 3
are addressed.
4 CHAIR KIRCHNER: Are there any --
5 MEMBER SUNSERI: Walt, this is Matt again.
6 You know, I think you made a comment that I want to 7
just talk about. Is you said something to the effect, 8
that the NuScale brought a complete design and that 9
others --
10 (Audio interference.)
11 MEMBER SUNSERI: -- if able.
12 MEMBER DIMITRIJEVIC: And this a problem.
13 CHAIR KIRCHNER: And Matt, we lost --
14 (Audio interference.)
15 MEMBER SUNSERI: You lost me?
16 CHAIR KIRCHNER: We lost, we didn't get 17 you comment, Matt.
18 MEMBER SUNSERI: Can you still hear me?
19 CHAIR KIRCHNER: Yes, now we hear you.
20 MEMBER SUNSERI: Okay. Well, I didn't 21 move, so maybe the internet glitched.
22 CHAIR KIRCHNER: Yeah, it probably 23 blinked.
24 MEMBER SUNSERI: So, let me just, I'll 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
89 just briefly restate. I thought your comments about, 1
you know, the completeness of the review allowing us 2
to do a thorough safety review, was very good. And I 3
would state that in a positive way going forward in 4
knowing that there are more designs coming. You know, 5
we would expect those designs to be complete enough, 6
so that we could do an efficient use of our time and 7
their time.
8 Something to that nature, because that's 9
not a NuScale specific, but it's a specific comment 10 from our review of the NuScale specific. Once again, 11 we're writing the Commission about safety matters.
12 And if we're talking, if reviewing of future 13 applicants is a safety matter, then we should discuss 14 that lesson in there. End of comment.
15 CHAIR KIRCHNER: Got it, thank you. Any 16 further input?
17 (No audible response.)
18 CHAIR KIRCHNER: Okay. I have an action 19 then to get you an actual detailed outline. And I 20 will reflect as best as I can, the input that I 21 received. And I'll try and get that to you shortly.
22 And then I'll lean -- oh, I was starting to make 23 assignments.
24 So, Vesna, I need input from you on 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
90 PRA aspect. We certainly want to, that's a touchstone 1
obviously in the application, and in our review.
2 MEMBER DIMITRIJEVIC: But Mike should have 3
that. I sent it to Mike for his, to hear his opinion 4
on how that would fit. So, I just sent it late last 5
night, so.
6 CHAIR KIRCHNER: Okay. Thank you.
7 MEMBER SUNSERI: Thanks, I'll shoot that 8
to the Members at lunchtime.
9 CHAIR KIRCHNER: Okay.
10 MEMBER SUNSERI: Walter, did you want to 11 do the ECCS, the ECCS valve performance?
12 CHAIR KIRCHNER: Well, that would be 13 Craig, yes. And then Tom, your input on the EDAS 14 would be valued. And but that's my sense right now.
15 And I got your message, Dave. And but I see a fairly 16 succinct, I think it's a positive letter. That's 17 where I am, so, if I'm missing something, Members, 18 that you want to highlight, this would be a good time 19 for us to discuss it because again, our target is to 20 have a letter, a complete letter coming out of the May 21 full committee meeting.
22 MR. SNODDERLY: So, Walt, one thing I 23 would like to ask Dave is, I went back and looked at 24 the Kairos letter. I really liked it and I liked how 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
91 the figures of merit were introduced at the beginning.
1 When I tried to do that for the NuScale, I was coming 2
up with the same ones, the same figures of merit, 3
light water reactor. In other words, I think it would 4
help, it would have helped, like what particular 5
figures of merit you wanted to call out. I think you 6
kind of mentioned already the fact it's completely 7
passive design.
8 MEMBER PETTI: Yes, I mean, I don't think 9
we actually ever said that in the last letter.
10 (Simultaneous speaking.)
11 MR. SNODDERLY: We didn't. We did though 12 13 MEMBER PETTI: You know, I mean --
14 MR.
SNODDERLY:
The first meeting 15 recommendation though, was, is the natural -- the 16 first recommendation, NuScale, small, SMR is a 17 natural-circulation, pressurized water reactor that 18 incorporates unique design and passive safety 19 features, providing enhanced margins of safety. There 20 is reasonable assurance that it can be constructed and 21 operated without undue risk to the health and safety 22 of the public. So, that was the first. So, you know.
23 (Simultaneous speaking.)
24 MR. SNODDERLY: Anyways, I, that was 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
92 challenge I had, I think that maybe it would help 1
avoid my, ability to share those thoughts. I'm like 2
that's the only reason I didn't put it in this 3
version, because I was struggling, but --
4 CHAIR KIRCHNER: Okay. Members online, 5
being Dennis and Stephen, have you any input you would 6
like to share?
7 (No audible response.)
8 CHAIR KIRCHNER: Well, you don't have to 9
do it in real time, but do you have my email address?
10 DR. SCHULTZ: I've got it Walt, this time.
11 CHAIR KIRCHNER: Yes.
12 DR. SCHULTZ: I'll weigh in on a couple 13 topics. Thank you.
14 CHAIR KIRCHNER: All right. Thank you.
15 All right, I'm not going to drag this out, we've got 16 a large audience.
17 (Simultaneous speaking.)
18 MEMBER PETTI: You want to talk about 19 EDAS?
20 CHAIR KIRCHNER: EDAS is, well.
21 MEMBER PETTI: I thought we were going to 22 have a discussion.
23 CHAIR KIRCHNER: Have a discussion.
24 VICE CHAIR HALNON: Yes, I just 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
93 summarize where it's going, just to close the loop.
1 CHAIR KIRCHNER: Okay.
2 VICE CHAIR HALNON: Okay. So, yesterday 3
we did get into discussion on a differing opinion and 4
that is being processed. And we're not going to get 5
in the middle of that in any way, we will let it be 6
processed. We also affirmed that there was some 7
options to resolve, from a NuScale perspective, one of 8
which was tension exemptions, staff generated 9
exemptions 84. There were some options put on the 10 screen. You could angle for another potential option 11 is 50.69 as another potential option to resolve this.
12 In addition to that I asked some questions 13 today about the definition of safety-related and how 14 that fits. And I think that's input into the 15 discussion that they're going to be having on the 16 differing opinion aspect. So, from a Committee 17 perspective, we're on a stand-by mode on that.
18 I believe we should probably get some 19 feedback on it in the future, whether it is closed 20 out. Is that acceptable, Becky, for you all to 21 provide us at least a status, an ongoing status and 22 also resolution, the resolution on what the differing 23 opinion is, is if you'd --- yes, Michelle, you want to 24 say something?
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94 MS. SAMPSON: Sure, sure. So, we can 1
certainly continue to provide an update on the status.
2 And it is possible that we will have resolution before 3
the May meeting. We'll update you and let you know.
4 VICE CHAIR HALNON: Yes, if you could 5
update us, in May then, that would be great. And the 6
reason this is important is because it's setting a 7
potential precedence going forward. And we just want 8
to make sure that we as a Committee, agree with the 9
resolution of it or if we have additional 10 recommendations or advice that we can get.
11 So, it's not that, again, we don't want to 12 get in the middle of it, but it's an important a piece 13 of design going forward. We want to make sure that 14 we're moving collectively. So, that's where I see it 15 is. I think the link is link is closed at least for 16 this meeting. And we'll get a future update. Tom did 17 you have something?
18 MEMBER ROBERTS: Yes, I raised the issue 19 yesterday about other causes for untimely actuation of 20 an RVV. Things like single failure while operating 21 with a, you know, redundant component out of service 22 or inadvertent actuation of ECCS by the operator. At 23 least for the redundancy, the applicant raised the 24 point that their tech specs do require as assessment 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
95 of the probability, and the frequency of ECCS 1
actuation all the time, instead of when you remember 2
redundancy. There is a tech spec requirement to go an 3
evaluation based on old topical report that said this 4
evaluation should be at least once in the lifetime of 5
the plant.
6 And to me, that is an acceptable solution 7
to the question of redundancy. So, even though the 8
redundancy is not managed in the tech specs directly, 9
it is managed indirectly by this analysis requirement.
10 So, that's why I planned to write up that the issue, 11 EDAS is not a complete statement of the problem, but 12 there is, you know, a tech spec that covers other 13 aspects of it.
14 And in terms of the EDAS, I'd written up 15 back in January, I think it was, an assessment of the 16 redundancy of the EDAS. And the equivalent is being 17 safety related. And at this point, I see there is no 18 change to that. And so, I don't think the staff has 19 agreed either. I think the staff not concurring, as 20 I understand it, is not getting at the design for the 21 intended operation. It's how you documented and how 22 you controlled it. You know, an administrative 23 documents and I don't think that's really something 24 that we need to be that involved with, as long as 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
96 there is agreement of the overall design and the 1
intent as to how it is to be operated is, you know, it 2
is clear. And that's where I'm at, and that's what I 3
intended.
4 VICE CHAIR HALNON: Yes, I think that's 5
right. And I probably should have said that overall 6
from the technical design perspective, it's where it 7
is. It's fine. It's reliable. It's redundant on, in 8
the process piece, how you call it. Then we have 9
ramifications in the commercial aspect of it down the 10 road. But we're not as concerned with that.
11 However, for future reactors, we're going 12 to have this question come in again. And we need to 13 make sure that we're applying the definitions 14 appropriately, and we understand how they're being 15 applied by the staff.
16 MEMBER ROBERTS: Right, it's also the 17 question of clearer explanation in the safety analysis 18 documents, what the basis is. And I think that's part 19 of also what the non concurrence is getting at. As 20 long as there's enough there that the applicant can do 21 their intensive repetitive or 59 evaluations in 50 22 years and understand what the basis is. And what they 23 might be challenging. That's the other aspect of it.
24 VICE CHAIR HALNON: Yes.
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97 MEMBER ROBERTS: But I think the staff is 1
all over that.
2 VICE CHAIR HALNON: Okay. That's enough 3
said at this point.
4 MEMBER ROBERTS: Okay.
5 VICE CHAIR HALNON: I think we're good and 6
I just want, again, wanted to make sure that we 7
summarized it so we can move forward.
8 CHAIR KIRCHNER: Okay. If there's no 9
other comments, input, from the Members then we'll 10 take a recess until 1 o'clock --
11 (Simultaneous speaking.)
12 VICE CHAIR HALNON: Well, we have P&P 13 Subcommittee --
14 CHAIR KIRCHNER: -- Eastern.
15 VICE CHAIR HALNON: P&P Subcommittee 16 meeting.
17 CHAIR KIRCHNER: And we, yes, we've all 18 waived that lunch time for a P&P Subcommittee meeting, 19 and Members are welcome to attend. And then again --
20 (Audio Interference) 21 CHAIR KIRCHNER: And then we'll reconvene 22 23 (Audio Interference) 24 VICE CHAIR HALNON: Larry Burkhart.
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
98 (Laughter.)
1 VICE CHAIR HALNON: Sorry, I'm watching 2
you.
3 CHAIR KIRCHNER: We will reconvene at 1 4
o'clock. We are in recess.
5 (Whereupon, the above-entitled matter went 6
off the record at 10:56 a.m. and resumed at 1:02 7
p.m.)
8 CHAIR KIRCHNER: Good afternoon, the 9
meeting will come to order. This is the afternoon of 10 the first day of the 724th meeting of the Advisory 11 Committee on Reactor Safeguards. I'm Walter Kirchner, 12 Chairman, the ACRS.
13 The ACRS Members in attendance in person 14 are, Ron Ballinger, Vicki Bier, Craig Harrington, 15 Gregory Halnon, Robert Martin, Scott Palmtag, David 16 Petti, and Thomas Roberts.
17 Members in attendance virtually via Teams 18 are Vesna Dimitrijevic, and Matt Sunseri. Our 19 consultants participating today virtually are Steve 20 Schultz and Dennis Bley. If I've missed anyone, 21 either Members or consultants, please speak up.
22 Christopher Brown, of the ACRS staff, is 23 the Designated Federal Officer for this afternoon's 24 full Committee meeting. No Member conflicts 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
99 interest were identified. And I note that we have a 1
quorum.
2 The ACRS was established by statute and is 3
governed by the Federal Advisory Committee Act or 4
FACA. The NRC implements FACA in accordance with our 5
regulations.
Per these regulations, and the 6
Committee's bylaws, the ACRS only speaks through its 7
published letter reports.
8 Member comments therefore, should be 9
regarded as only the individual opinion of that Member 10 and not a Committee position. All relevant 11 information related to ACRS activities, such as 12
- letters, rules for meeting participation, and 13 transcripts are located on the NRC public website and 14 can be easily found by typing about us, ACRS, in the 15 search field on NRC's homepage.
16 The ACRS, consistent with the Agency's 17 value of public transparency in regulation of nuclear 18 facilities, provides opportunity for public input and 19 comment during our proceedings. We have received no 20 written statements or requests to make an oral 21 statement from the public, however, we've set aside 22 time at the end of this meeting for any comments from 23 the public.
24 Written statements may be forwarded 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
100 today's Designated Federal Officer. And that's 1
Christopher Brown. A transcript of the meeting is 2
being kept and will be posted on our website. When 3
addressing the Committee, the participant should first 4
identify themselves and state with sufficient clarity 5
and volume, so that they may be readily heard.
6 If you're not speaking, please mute your 7
computer, on Teams. If you're participating by phone, 8
press *6 to mute your phone, and *5 to raise your hand 9
on Teams. The Teams, Chat feature, will not be 10 available for use during the meeting. For everyone in 11 the room, please put your electronic devices in silent 12 mode and mute your laptop microphone and speakers.
13 In
- addition, please keep side bar 14 discussions in the room to a minimum since the ceiling 15 microphones are live.
16 Presenters, your table microphones are 17 unidirectional. You'll need to speak into the front 18 of the microphone to be heard online. Finally, if you 19 have any feedback for the ACRS about today's meeting, 20 we encourage you to fill out the public meeting 21 feedback form on the NRC's website.
22 This afternoon, the Committee will 23 consider Terrestrial Energy's Topical Report on 24 Principle Design Criteria as stated in the agenda.
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
101 Portions of this meeting may be closed to protect 1
sensitive information as required by FACA and the 2
Government in the Sunshine Act.
3 Attendance during the closed portion of 4
the meeting will be limited to NRC staff and its 5
consultants, Terrestrial Energy and those individuals 6
and organizations who have entered into an appropriate 7
confidentiality agreement. We will confirm that only 8
eligible individuals are in the closed portion of this 9
meeting.
10 And with that, I will pass the microphone 11 to Scott Palmtag, who is the Chair of our Terrestrial 12 Energy Design Center Subcommittee. Scott.
13 MEMBER PALMTAG: Thank you, Chairman.
14 Just go ahead and read the letter and --
15 CHAIR KIRCHNER: Do you want to summarize 16 at all, what was done at the Subcommittee meeting 17 before we start the letter writing?
18 MEMBER PALMTAG: We had a Subcommittee 19 meeting on the Terrestrial, TEUSA, Terrestrial pro --
20 on the design criteria for the Integral Molten Salt 21 Reactor, the IMSR. we heard the presentations from 22 the Terrestrial and from the staff.
23 CHAIR KIRCHNER: Good, okay.
24 MEMBER PALMTAG: All right. We have a, I 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
102 have a draft letter. I'll go ahead and read it. So, 1
get it a little smaller, so you can see the, all the 2
way across. All right. That's perfect.
3 "During the 724th meeting of the Advisory 4
Committee on Reactor Safeguards, April 2 to the 4, 5
2025, we completed our review of, Draft of the Safety 6
Evaluation, Regarding the Principal Design Criteria, 7
Integral Molten Salt Reactor, IMSR, Structures, 8
Systems and Components Topical Report, Revision C and 9
the associated safety evaluation, SE. Our Terrestrial 10 Energy Subcommittee also reviewed this matter on March 11 20, 2025. During these meetings, we had the benefit 12 of discussions with the Nuclear Regulatory Commission, 13 NRC, staff, and Terrestrial Energy USA, TEUSA."
14 Scroll down. "We also had the benefit of 15 the referenced documents."
16 "Conclusions and Recommendations, one, the 17 Principal Design Criteria, PDC, proposed by TEUSA for 18 the IMSR reactor have been developed by adapting 19 Advanced Non-Light-Water Reactor design criteria from 20 NRC guidance, design criteria from a draft American 21 National Standards Institute, ANSI, American Nuclear 22 Society, ANS, standard for MSR design criteria, and 23 consideration of the unique design features of the 24 IMSR."
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
103 "Second, considering the lack of recent 1
operating experience with MSR technology, the staff 2
should consider amending the SE limitations and 3
conditions to require the addition of a safe shutdown 4
system for reactivity control, and to require 5
demonstrating the capability to achieve a subcritical 6
condition, in this first of a kind reactor."
7 "Three, the PDC proposed by TEUSA 8
eliminate several design criteria used in other 9
reactor designs, including those that support defense 10 in depth. Considering the lack of recent operating 11 experience with MSR technology, additional 12 justification needs to be provided for these 13 decisions, as indicated in the draft SE."
14 "Four, the final IMSR PDC should be made 15 available publicly in a non-proprietary format to 16 adequately inform the public that the reactor is 17 designed and reviewed in a safe manner."
18 Background Section, "the General Design 19 Criteria, GDC, for Nuclear Power Plants, Appendix A to 20 Title 10 of the Code of Federal Regulations, 10 CFR, 21 Part 50, are the minimum requirements for the PDC for 22 water-cooled nuclear plants to provide reasonable 23 assurance that a facility can be operated without 24 undue risk to the health and safety of the public."
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
104 "The GDC were developed to focus attention 1
on the most prominent issues and improve the 2
predictability and efficiency of NRC reviews of 3
licensing applications.
Design criteria are 4
established to provide a solid basis for the staff 5
review and ensure that a given facility can be 6
operated safely.
They provide assurance that 7
structures, systems, and components, SSCs, important 8
to safety will remain functional during and following 9
identified design basis events."
10 "Regulatory Guide, RG, 1.232, Guidance for 11 Developing Principal Design Criteria for 12 Non-Light-Water Reactors, provides guidance on how the 13 GDC can be adapted for non-light-water reactor, 14 non-LWR, designs. It includes generic advanced 15 reactor design
- criteria, technology-specific 16 sodium-cooled fast reactor design criteria, SFR-DC, 17 and modular high temperature gas-cooled reactor design 18 criteria."
19 "The criteria established in this 20 regulatory guide are based on extensive interactions 21 among NRC, the Department of Energy and experts in the 22 nuclear community in each of the technologies. The 23 regulatory guide notes that applicants may need to 24 develop entirely new PDC to address unique design 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
105 features. Early engagement and agreement on plant 1
specific PDC facilitate a more effective design 2
development and regulatory review."
3 Terrestrial Energy USA is developing the 4
Integral Molten Salt Reactor. The IMSR nuclear power 5
plant site consists of two Reactor Auxiliary 6
Buildings, RAB, and a single Control Building. Each 7
RAB has a single operating IMSR Core-unit. Each Core 8
unit consists of a 442-Megawatt thermal molten salt 9
reactor, MSR."
10 "RG 1.232 does not include technology 11 specific design criteria for MSRs, so TEUSA has 12 developed the IMSR PDC by adapting the design criteria 13 from other PDC listed in RG 1.232 for advanced 14 technologies. TEUSA has also considered draft 15 guidance from the development of the ANSI/ANS standard 16 for MSRs, ANSI/ANS-20.2-2023, Nuclear Safety Design 17 Criteria and Functional Performance Requirements for 18 Liquid-Fuel Molten Salt Reactor Nuclear Power Plants."
19 This standard has since been finalized.
20 "However, ANSI/ANS standard MSR design is 21 based on a functional containment, while the IMSR has 22 a traditional containment. These factors lead to the 23 IMSR having a unique set of PDC."
24 "Discussion, molten salt reactors are 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
106 Gen-IV reactor concepts that have several potential 1
advantages over current light-water reactors in terms 2
of safety and economics. However, the operating 3
experience of MSRs is small and based mostly on the 4
Molten Salt Reactor Experiment, MSRE, that operated at 5
Oak Ridge National Laboratory in the 1960s at a power 6
level of 7.4 Megawatt thermal."
7 "Lack of recent operating experience and 8
operating experience at higher power levels suggests 9
retaining many of the traditional requirements in the 10 PDCs that the applicant proposed deleting or scaling 11 back. The proposed PDC for reactivity control in the 12 IMSR is novel and does not conform to PDC used in 13 existing power reactors and proposed in other advanced 14 light-water reactors."
15 "Bullet 1, we acknowledge the strong 16 negative temperature coefficient associated with the 17 design, however it is not unique as other reactors 18 also have this characteristic."
19 "Second
- bullet, because of the 20 complexities, uncertainties and time constants 21 associated with the underlying phenomena, inherent 22 negative reactivity feedback has historically been 23 demonstrated in test reactors and prototypes prior to 24 taking credit for this characteristic in power 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
107 reactors" 1
"Examples include negative feedback from 2
rod bowing and growth in fast reactor metallic fuel 3
assemblies in EBR-II and the Fast Flux Test Facility, 4
demonstration of the High Temperature Gas-Cooled 5
Reactor, HTGR, negative temperature coefficient in 6
AVR, HTTR and HTR-10, and confirmation in the Chinese 7
commercial HTR-PM. No such testing exists for this 8
technology as applied in the IMSR."
9 "Third bullet, while the use of liquid 10 fuel enhances the negative reactivity coefficient, 11 this is offset by uncertainties associated with the 12 first-of-a-kind nature of the facility and unique 13 geometry. It is prudent to use a more traditional 14 approach that has proven to execute the safety 15 function to control reactivity in a reliable manner 16 until sufficient operating experience is gained."
17 "The ANCI/ANS standard has developed a set 18 of principle design criteria from molten salt reactor 19 designs adapted from these developed for high 20 temperature in gas-cooled reactor. Criteria 20, 26, 21 28 and 29 relate to reactivity control in such 22 systems."
23 "They require, (a) a reactor protection 24 system, (b) two independent and diverse means 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
108 shutting down the reactor (required for all reactor 1
systems, (c) systems to limit the amount and rate of 2
reactivity increase to ensure the integrity of the 3
salt boundary and the reactor core, and (d) such 4
systems to be able to execute safety functions with 5
high probability of success in the event of an 6
anticipated operating occurrence."
7 "These criteria need to be considered in 8
light of the salt fueling system which is essentially 9
a reactivity addition system. There need to be limits 10 on that system in terms of its ability to add 11 reactivity in order to prevent or limit reactivity 12 increases due to inadvertent over-fueling of the 13 reactor."
14 "Proposed PDC on reactor shutdown included 15 in TEUSA-26 criterion is also novel. One of the 16 fundamental safety functions is the control of fission 17 process, which has traditionally been interpreted as 18 always being able to place the reactor in a 19 subcritical state."
20 "Relaxing this requirement to only require 21 the reactor to be in a, quote, "safe state", unquote, 22 depends on the definition of a, safe state, and the 23 ability to demonstrate by analytic means that a safe 24 state can be achieved. This demonstration may 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
109 limited by validation of the computer codes used in 1
such a calculation and uncertainties in cross sections 2
and the movement of delayed neutrons associated with 3
the dissolved fuel out of the core used in the 4
feedback analysis."
5 "In addition, due to the first of a kind 6
nature of this design, there may be unknown scenarios 7
where the, safe state, cannot be obtained. It is 8
therefore prudent to include the traditional 9
requirement that a safety-related shutdown system be 10 available to ensure that the reactor can always be 11 brought to a subcritical state."
12 "We also note that the design does not 13 implement two independent means of shutdown. The two 14 independent means are imposed as a measure of defense 15 in depth, to assure that reactor shutdown is 16 accomplished with an extremely high degree of 17 reliability. A stronger rationale is needed that 18 addresses the safety philosophy associated with this 19 requirement."
20 "One feature of molten salt reactors is 21 that gaseous fission products are released from the 22 reactor core and are not contained in fuel rods. In 23 the preliminary IMSR design, the fission product gas 24 is contained in a gas holding tank for the entire life 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
110 of the IMSR."
1 "The source term from this gas holding 2
tank could be significant and the final design should 3
consider the consequences of a tank leak and glitch.
4 It is premature to preclude that a containment 5
atmosphere cleanup system is not necessary until the 6
final design of this system, and consequences of a 7
release, have been completed."
8 "Finally, the treatment of the IMSR PDC as 9
proprietary is a new approach. While it may be 10 reasonable for the initial PDC to remain proprietary 11 as the reactor design is developed, the PDC are 12 fundamental to reactor safety and should be available 13 to the public. The PDC inform the public that the 14 reactor is designed and reviewed in a safe manner.
15 Hence, the final IMSR PDC should be publicly 16 available.
17 "Summary, summary will be mainly copied 18 from the app, once we finalize the letter, so -- "
19 CHAIR KIRCHNER: Thank you, Scott. So, 20 Members, high level comments?
21 MEMBER SUNSERI: Hey, this is Matt. I 22 have one high-level comment and it regards the rod 23 control system, to shut down the reactor, which it's 24 my understanding they do have one, right? They 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
111 a way for the operator to manually insert the control 1
rods to maintain shutdown from the safe state. Is 2
that correct?
3 MEMBER PALMTAG: Right. They do have one 4
but it's not safety-grade.
5 MEMBER SUNSERI: So, a PWR has the same 6
exact feature, the rod control system is not safety 7
related. The reactor protection system is safety 8
related and it opens the reactor trip breaker but all 9
the equipment is non-safety related. So, I don't see 10 what our grievance is with what they're proposing, 11 other than it's not safety related. Neither is the 12 PWRs though.
13 MEMBER ROBERTS: Hey, Matt, this is Tom.
14 I guess I question that. At least my understanding is 15 the RTVs and all the reactor protection circuitry that 16 drives their under voltage function. are safety 17 related.
18 CHAIR KIRCHNER: Are safety, yeah --
19 (Simultaneous speaking.)
20 MEMBER ROBERTS: And the boundary is, 21 certainly the circuitry that moves the rods tends to 22 not be safety related. But the cords and circuitry 23 that interrupt power to the control rod drives are of 24 safety -- at least in my background.
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112 MEMBER SUNSERI: The control rod drives in 1
the Westinghouse, at least plants I'm familiar with, 2
is all non-safety related. All the control cards, all 3
the circuits. The motorized, motor generator sets 4
everything up to the reactor trip breakers themselves.
5 But the --
6 MEMBER ROBERTS: Right.
7 MEMBER SUNSERI: So, the reactor trip 8
breaker is the --
9 MEMBER ROBERTS: The reactors, but the 10 next trip break will take away power to all those 11 things, you know. And allows the rods to passively 12 drop.
13 CHAIR KIRCHNER: The protection system 14 itself that actuates, is safety.
15 MEMBER ROBERTS: Right. All the way 16 through the reactor trip breaker step, to the power 17 that the reactor trip breaker switch is hooked in on 18 is safety. But, you know, if the oscillating power 19 goes away, you scram anyway. So, the scram function 20 is, at least to my understanding, is safety in other 21 plan designs.
22 I think that's the point that Scott is 23 making here. Is there is no, there's no intent to 24 make the reactor trip system or the, you know, 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
113 whatever part of the reactor tool that actually drops 1
the rods to be safety. That right, Scott?
2 MEMBER PALMTAG: Yes.
3 MEMBER SUNSERI: That's not what I'm 4
understanding. The way it's reading is, it doesn't 5
read to me that way. I mean, we're saying that the 6
safe state is not, there is not a reactor protection 7
system to achieve the safe state. And we don't have 8
a grievance with that.
9 Our grievance is, is that once we're in 10 the safe state, how do you shut down the reactor? The 11 Applicant said, well, they have this rod control 12 system that the operator can manually actuate to shut 13 down a reactor. And that's no different than a PWR.
14 CHAIR KIRCHNER: No it is.
15 MEMBER SUNSERI: It is not. But I don't 16 understand why you don't under --
17 (Simultaneous speaking.)
18 CHAIR KIRCHNER: You have a reactor --
19 MEMBER SUNSERI: -- an operate --
20 CHAIR KIRCHNER: -- protection system that 21 actuates that by releasing, you know, the power, and 22 the rods drop because of gravity. That's not -- you 23 have a manual scram on the PWRs but the reactor 24 protection system is a safety-related system.
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114 MEMBER SUNSERI: I'm saying, but, so, 1
you're saying that you have to have a safety-related 2
system to manually open the reactor trip breaker by an 3
operator?
4 MEMBER PALMTAG: Well, there's two pieces.
5 There's the actual ability to shut down the system, an 6
operator. And then there's a reactor protection 7
system for example, hi flux alarms or some high 8
temperature
- alarms, or something that would 9
automatically scram the reactor. They have no reactor 10 protection system.
11 MEMBER SUNSERI: Right. Because their 12 physics demonstrate that they go to the safe state.
13 Right.
14 MEMBER PALMTAG: Right.
15 MEMBER SUNSERI: I thought we didn't have, 16 I didn't think we had a grievance with that not being 17 a safety-related function. That we were relying on 18 the physics for that. I thought our grievance was 19 solely with, they didn't have a safety-related record 20
-- rod control system to open the reactor trip 21 breakers.
22 MEMBER PALMTAG: I think they're both. My 23 understanding is both issues. You have to have a 24 safety system to shut down the reactor. And then is 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
115 there apart, automatic protection system? Reading 1
wasn't right, I'm afraid.
2 (Simultaneous speaking.)
3 DR. BLEY: This is Dennis and I'm 4
listening to this and I think everybody is talking 5
past each other. What I hear, not saying, is that the 6
mechanical mechanisms, the motors are all in the line 7
of safety related. The place there, I'm not sure of, 8
and I agree with him on that, the place I'm not sure 9
of is the actual latching mechanism, if there's 10 anything safety related about that?
11 On the other side, the trip breakers and 12 the logic that opens the trip breakers, the reactor 13 protection system, is safety related on a light-water 14 reactor, I mean on PWRs. So, the only question I had 15 sitting there is, is there anything in the mechanical 16 unlatching mechanism, after you kill the power that's 17 safety related? Because I know the motors and that 18 sort of stuff's not.
19 MEMBER SUNSERI: Well, my experience is 20 the control rod mechanism coils on the reactor vessel 21 head are non-safety related.
22 CHAIR KIRCHNER: That's correct, Matt.
23 But the protection system that initiates the scram is 24 safety related.
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116 MEMBER SUNSERI: Yes, so let's just divide 1
up the two issues, because we are talking about two 2
separate things. I'm talking about taking the reactor 3
from a safe shutdown state, which they've defined.
4 And then they show they get to with their physics.
5 I'm talking about taking from that to a subcritical 6
shutdown state, using the manually operated rod 7
controls, non-safety related system. That's what I'm 8
talking about. And that does take the reactor to a 9
shutdown state, in my view.
10 I'm not arguing right now, about whether 11 or not they need a reactor protection system to 12 achieve the safe state. We can have that discussion 13 separately. But what I heard very clearly at the 14 Subcommittee meeting was, because they did not have a 15 safety-related rod-drive system, I'll call it that, 16 that we had a grievance with that. And I just, I'm 17 pushing back on that point.
18 VICE CHAIR HALNON: I think that -- this 19 is Greg. I've broken it with basically, two 20 questions, right. In my mind, the first question is, 21 if we'd would accept physics in place of the 22 safety-related reactor protection circuit? That's 23 what shuts the reactor down in a pinch in a safe 24 state. And the second question is, going from 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
117 safe state, to a shutdown, is the rod control system 1
that they have adequate, not, safety related or not 2
safety re -- I think it's --
3 What I think we're mixing up is that we're 4
saying instead of physics, you need a safety-related 5
rod-control system that trips the reactor. I think 6
that's the second question. Is the rod control system 7
for that second diverse means of shutting down the 8
reactor, adequate?
9 The first question is, do we accept the 10 natural physics of the core in place of a
11 safety-related reactor-protection system?
12 MEMBER PETTI: And I think the letter 13 says, no. Because it hasn't been demonstrated.
14 VICE CHAIR HALNON: Right, for lack of 15 operating experience.
16 MEMBER PETTI: Ron says. I mean, we in a 17 generic sense, we accept this sort of physics in other 18 systems that have that demonstrated. And we comment 19 on that. And in fact, if you go and look at, I think, 20 Reg Guide 1.232 and look at the gas reactor PDC, you 21 are allowed to use the negative temperature 22 coefficient as your secondary means of shutdown.
23 Whereas --
24 (Simultaneous speaking.)
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118 VICE CHAIR HALNON: Secondary.
1 MEMBER PETTI: And that's a change from 2
say, 20 years ago. There used to be two shutdown 3
systems, independent and diverse to shut down a gas 4
reactor. Classic rods and they had a separate special 5
system, little balls.
6 CHAIR KIRCHNER: Yes. Conditions.
7 MEMBER PETTI: That has moved forward 8
because it's been demonstrated in so many gas 9
reactors. Similarly, fast reactors, that's what I put 10 in. Is an inherent reactivity feedback in the 11 metallic core that's been demonstrated on two metallic 12 reactors.
13 VICE CHAIR HALNON: The dome.
14 MEMBER PETTI: So again, I don't have a 15 problem in an, nth of a kind, but for the first of a 16 kind. It seemed like it should be proven to have such 17 a system.
18 MEMBER PALMTAG: Related to that we have 19 to do, it hasn't been defined what exactly a safe 20 state means.
21 MEMBER PETTI: Yes.
22 MEMBER PALMTAG: And what's the power, and 23 that goes back to first of a kind versus Nth of a 24 kind.
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119 CHAIR KIRCHNER: What is a safe state and 1
is it a, is safe, non-critical, sub-critical, or not?
2 MEMBER PALMTAG: I believe it's not 3
sub-critical in this case. Again --
4 CHAIR KIRCHNER: It's critical?
5 MEMBER PALMTAG: For example if you have 6
positive reactivity, you have a negative reactivity 7
coefficient. Fine, it drops the power, but it could 8
drop it to 80 percent. Is that a safe state or not?
9 VICE CHAIR HALNON: So, that's a third 10 question.
11 MEMBER PALMTAG: Lesson three.
12 CHAIR KIRCHNER: Yes.
13 MEMBER PETTI: Lesson there.
14 CHAIR KIRCHNER: So, it --
15 VICE CHAIR HALNON: But, in essence I 16 agree with Matt. The rod control system in this, 17 doesn't need to be safety related. Because it's not 18 entirely --
19 (Simultaneous speaking.)
20 CHAIR KIRCHNER: Yes, the rod control 21 system --
22 VICE CHAIR HALNON: Watch out.
23 CHAIR KIRCHNER: -- usually is not safety 24 related.
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120 VICE CHAIR HALNON: Right.
1 CHAIR KIRCHNER: Because in a PWR, you 2
unlatch the rods and they drop by gravity.
3 VICE CHAIR HALNON: Right. And then 4
anything that causes that unlatching is safety 5
related.
6 CHAIR KIRCHNER: And everything up to the 7
unlatching is, is a safety --
8 VICE CHAIR HALNON: That's where these 9
questions just overlap. We're not talking about the 10 thing that scrams reactor or puts it into the safe 11 state. We're talking about a rod control system 12 that's operated by the operators to drive it to -- is 13 that the verse, secondary, if you will, reactivity 14 control to drive to a safe state? Which may be a 15 different safe state.
16 So, the first question is, do we accept 17 safe state being critical? Second question is, do we 18 accept the physics being the, basically, RPS, reactor 19 protection system? And then the third question is, is 20 the rod control system being used by the operators 21 adequately, adequately classified in design? I think 22 that third question is, yes.
23 MEMBER ROBERTS: I would change the third 24 question to, does it meet redundant needs to 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
121 provided? I just skimmed through his last letter, I 1
didn't see anything about rod control on there. And 2
I'm not sure where the argument is coming from.
3 (Simultaneous speaking.)
4 VICE CHAIR HALNON: I don't think, Matt is 5
there any --
6 MEMBER ROBERTS: I don't think anybody is 7
claiming they needed a safety related rod control 8
system.
9 CHAIR KIRCHNER: No.
10 MEMBER ROBERTS: I think the question, the 11 third question is, is there a need for a redundant 12 means of shutdown?
13 VICE CHAIR HALNON: Yes, I think Matt was 14 going back to the Subcommittee discussion, rather than 15 what's in the letter, basically, right?
16 MEMBER ROBERTS: But the manual is saying 17 18 (Simultaneous speaking.)
19 VICE CHAIR HALNON: Or diverse means.
20 MEMBER ROBERTS: It could be diverse 21 means.
22 VICE CHAIR HALNON: Like with GDC 27, could 23 be diverse means, it'll shut it down. So there is two 24 diverse means if you accept the physics part as being 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
122 the RPS.
1 CHAIR KIRCHNER: Maybe for context, you 2
know, list it as Dave was saying, back -- and I can't 3
remember the SECY, I want to say it's93-087, but 4
don't quote me on that. But when the advanced small, 5
the SMRs were being considered in the late 80s or 6
early 90s, there was a recognition that those non-LWR 7
reactors could not effect a cold shutdown, as was 8
required of the PWR fleet and the PWRs.
9 For a lot of obvious reasons you don't 10 want to go to cold shutdown in a sodium loop, because 11 it can freeze components and so on and so forth. So, 12 and for the HTGR, if I remember correctly, Dave, the 13 time it would take to cool down an HTGR with a large, 14 large thermal inertia of all the graphite, led to that 15 kind of policy statement in the SECY that bringing it 16 down subcritical, that's important, subcritical but at 17 temperature, would be adequate for those designs.
18 And I think that, the first order would 19 hold also with this design, because it's a salt system 20 and you don't want to freeze the salt obviously, or 21 the fuel somewhere else in the system. So, there's 22 that regulatory precedent that the expectation would 23 be of those advanced reactor designs at the time, that 24 they would be able to achieve subcritical.
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123 Those, both reactors as Dave said, had 1
strong negative temperature coefficient evac for 2
controlling potential reactivity insertion accidents 3
and other upsets. And that was recognized as well.
4 But they did require them to have a system that could 5
take them subcritical. That's my recollection notes, 6
where the agency was considering the first set of 7
modular non-LWR reactors.
8 So, the precedent here of going to a safe 9
condition that doesn't include subcritical, is 10 something that merits discussion. What is that 11 definition? And what is acceptable if it's not 12 subcritical?
13 MEMBER PALMTAG: Yes, that was one of the 14 recommendations.
15 VICE CHAIR HALNON: In Number 2.
16 MEMBER SUNSERI: Well, isn't it a matter 17 of timing? I mean, your question Walt, is a good one, 18 but it's timing, it's about timing, right? And just 19 like your discussion about what's cold? And when is 20 it appropriate to be cold? So, but if we're going to 21 accept this Generation IV reactor physics as a safe, 22 you know, to satisfy, you know, simplicity of the 23 design and enhanced safety, all that stuff that we're 24 talking about, we're going to have start switching our 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
124 mindset a little bit from, of the past things.
1 So, in this particular situation, does 2
being safe means that it has to be subcritical within 3
1.4 seconds like a PWR? Or can it be minutes after 4
the transient has played out, the safe state is 5
achieved. The reactor operator then sees he's got a 6
stable plant, and takes it to shut down by inserting 7
the control rods?
8 CHAIR KIRCHNER: Yes, but what has not 9
been explored yet, fully, is the range of transient 10 accident upset conditions and reactivity insertion 11 events that you can have with a liquid fueled system.
12 MEMBER SUNSERI: Yes, but isn't that what 13 these PDC are supposed to confine -- define?
14 CHAIR KIRCHNER: Well, the problem is the 15 PDCs that were proposed seemed to be silent on the 16 fact that they're using injection of liquid -- I 17 assume it's in a liquid salt mixture, as they hand it 18 to the primary system. So, you have to look at the 19 reactivity insertion accidents.
20 MEMBER PALMTAG: Yes, but are you, I still 21 would argue this is going back to our earlier 22 discussions on other designs. You know, part of 23 safety, you have to have a safety system that goes 24 subcritical.
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125 The physics will take you -- are negative 1
feedback, but that does, that could be, you know. It 2
doesn't go all the way down to zero. It could still 3
be 80 percent, 60 percent, 40 percent even, if you 4
like. I look at it, you need a way to, you need an 5
off button.
6 CHAIR KIRCHNER: Yes. The physics could 7
take you to above 100 percent too.
8 (Simultaneous speaking.)
9 MEMBER PALMTAG: Yes. But the negative --
10 yes, well it depends --
11 CHAIR KIRCHNER: It depends on what's is 12 the transient.
13 MEMBER PALMTAG: Right. That's right, oh, 14 yes.
15 CHAIR KIRCHNER: Because if you have an 16 over-cooling transient, you're going to put in a lot 17 of reactivity.
18 MEMBER PALMTAG: Yes.
19 CHAIR KIRCHNER: And your question is, you 20 know, can you demonstrate that the feedback is 21 sufficient to offset the reactivity insertion from a 22
-- strong feedback goes both ways.
23 MEMBER PALMTAG: Right.
24 CHAIR KIRCHNER: Yes. So, it goes both 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
126 ways. Now it's well coupled because it's in the fuel 1
in a liquid form. But I don't know, has the full 2
spectrum of scenarios, and accident initiators been 3
examined?
4 VICE CHAIR HALNON: Is that a PDC topical 5
report issue or is that an L&P type, you know, 6
licensing based --
7 (Simultaneous speaking.)
8 MEMBER PETTI: Well, but if you don't have 9
a PDC, it says, that as the ANS standard says, that 10 you need to have a system to assure, to prevent a 11 limit reactivity increase, to do in -- you know, it 12 says here, it's Item D. "Executes safety functions 13 with high probability of success in the event of an 14 anticipated operating occurrence."
15 And so, if the fueling is coming in 16 liquid, an over-fueling event might be an AOO. Might 17 be an inadvertent over-fueling event. Well, how do 18 you deal with that? And how do you --
19 CHAIR KIRCHNER: It's fueling all the 20 time. It's going to be an AOO.
21 MEMBER PETTI: Yes, an AOO. So, how do 22 you, you know, prevent or limit that? There's not a 23 PDC even there, so there's nothing to check again.
24 That's the concern, is that there needs to be some 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
127 sort of a PDC that says, how am I designing against 1
this?
2 CHAIR KIRCHNER: Reactivity insertion 3
accidents, that's why you have --
4 (Simultaneous speaking.)
5 VICE CHAIR HALNON: My point is that --
6 CHAIR KIRCHNER: -- protection system.
7 VICE CHAIR HALNON: -- it shouldn't have 8
-- say you do have an over-fueling event or whatever 9
you might call it. The fact that there's not a PDC 10 there doesn't change the fact that you still are 11 postulating an over-fueling event. You've got to see 12 how the system's react to it. PDC will just ensure 13 that it's mitigated.
14 So, if you don't have a PDC and you 15 postulate that event, then it's just going to play out 16 to be a problem in whatever the end state of an 17 accident is. You might have melting fuel? I don't 18 know, it's already melted --
19 (Simultaneous speaking.)
20 MEMBER PETTI: Well, my concern is there 21 were a lot of smart people who developed the ANS 22 standard, molten salt people. I mean, I looked at the 23 list of people. To not adopt it --
24 VICE CHAIR HALNON: Would be exceptional.
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128 MEMBER PETTI: -- or to take exception to 1
it, requires I think, a very strong rationale. It 2
would be like, you know, you're going to adopt, You 3
know, you're not going to accept the ASME code for 4
something. It's kind of --
5 VICE CHAIR HALNON: No, I agree. And I 6
had the same problem with the fact that they didn't 7
use ACU as a benchmark against this. Because that was 8
the first one, and the staff reviewed it and then 9
approved their PDC. And none of them are based on the 10 same thing that they're --
11 MEMBER PETTI: Right. I'm --
12 VICE CHAIR HALNON: -- on it.
13 MEMBER PETTI: You know, I don't need 14 details, but, you know, when there's beryllium and 15 lithium in the salt, that's a very different feedback 16 response than when there's not. So, because there's 17 all these different salts, sometimes there's not as 18 much crossover between the designs.
19 VICE CHAIR HALNON: But it's still fine.
20 MEMBER BALLINGER: Why do we not just say, 21 that you have to comply with the ANS standard, unless 22 you provide for an exemption or justified exemption?
23 That's two or three sentences.
24 MEMBER PALMTAG: There's a few reasons 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
129 that, one, that when they developed these PDCs, the 1
ANS standard was still draft. So, this PDC, or the 2
ANS standard has just been finalized. And then there 3
are some differences between the ANS standard. The 4
ANS standard has a functional containment, where they 5
use a real containment. So, there are --
6 MEMBER PETTI: Yes, but that doesn't affect 7
reactivity. It's quite nice --
8 MEMBER PALMTAG: No, no.
9 MEMBER PETTI: -- that they can, they can 10 adopt the ANS standards verbatim is what my point is.
11 MEMBER BALLINGER: Well, I was going to 12 say, you don't to adopt verbatim, but they ought to be 13 able to say, we're going to adhere to the ANS 14 standard, with the following exception. Now, the fact 15 that it's just initiated, these guys have been doing 16 this for the last 10 years.
17 MEMBER PALMTAG: Yes. I think Dave did 18 have a conclusion, but Dave's comments are leading to 19 an additional conclusion that would say that in there.
20 MEMBER BALLINGER: I think I recall that 21 the MSRE their fueling system and their defueling 22 system were very different. You could defuel really 23 fast.
24 (Simultaneous speaking.)
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130 PARTICIPANT: They had a treatment --
1 PARTICIPANT: Oh, they had a fish pond.
2 MEMBER BALLINGER: Yes, yes.
3 CHAIR KIRCHNER: And then they dropped 4
into a subcritical configuration.
5 MEMBER BALLINGER: Yes, yes. So, you 6
physically couldn't add too much reactivity, there was 7
a limit. But for defueling, you could just shove the 8
thing down.
9 MEMBER PALMTAG: Yes, this design does not 10 have a drain plug at all.
11 MEMBER BALLINGER: Yes, I was surprised 12 that there wasn't some, I call it dump valve, 13 something.
14 CHAIR KIRCHNER: It's too much inventory 15 to make it practical actually. By the time you got it 16 drained, you've --
17 MEMBER BALLINGER: Yes.
18 CHAIR KIRCHNER: -- you would be operating 19 the whole time it was draining, until you got the fuel 20 level, the solution level below the moderator in the 21 fixed, you know, they have a fixed moderator, which is 22 the de facto, the place where you get fission. And 23 you would have to drain it all out to take the 24 moderator out of the equation.
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131 MEMBER PALMTAG: Yes, this system is about 1
50 times bigger than the MSREs. They do have a tube, 2
I say tube or pipe that goes to the bottom of the 3
tank. And it runs up and then over to another tank.
4 That's how they defuel and as they pressurize it, it's 5
a much slower process than a freeze plug.
6 VICE CHAIR HALNON: Would it be better 7
than to, an option to just focus in on the deviation 8
from the ANS standard PDCs, and rather than try to 9
suggest a fixed one?
10 MEMBER BALLINGER: That's what I was 11 trying to say.
12 MEMBER PETTI: Yes, I mean, the paragraph 13 that's edited in blue, was a late edition and I had 14 trouble figuring out where it best fit. I think it 15 needs to move up. Maybe it's how we start it.
16 CHAIR KIRCHNER: It's background.
17 MEMBER BALLINGER: Yes. That's got to, I 18 think that one, you put that right up front.
19 MEMBER PETTI: This is all of our 20 reactivity control.
21 MEMBER BALLINGER: But that's the main 22 think.
23 MEMBER PETTI: Yes, yes, yes.
24 MEMBER BALLINGER:
So, it's not 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
132 background, I think it leads into our discussion.
1 CHAIR KIRCHNER: It seems, I think Greg, 2
teed it up, but I'll try again. There are three 3
issues. Safe -- are we in agreement that a safe 4
condition is not subcritical?
5 Second, are we in agreement or not, 6
whether a protection system is -- we can piece part --
7 we take the system apart and decide what's safety 8
related or not. But I don't think that's the real 9
issue here. It's a more fundamental issue.
10 Do we have such confidence that there's no 11 reactivity insertion kind of event that could occur, 12 that would warrant not having the reactor shutdown 13 protection system? That is truly unprecedented.
14 MEMBER PETTI: It's just a -- and then for 15 a first of a kind.
16 CHAIR KIRCHNER: And for a first of a 17 kind. And then the other thing, what was the third 18 one that you --
19 VICE CHAIR HALNON: It got into the rod 20 control insertion accident, the diverse means and 21 redundancy, 22 CHAIR KIRCHNER: Yes.
23 Well, the history of liquid systems with 24 fissile solutions and criticality events is --
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133 MEMBER BALLINGER: There have been some 1
pretty spectacular criticality events.
2 CHAIR KIRCHNER: Yes, so --
3 MEMBER PETTI: Some of the most --
4 MEMBER BALLINGER: Yes, not least of which 5
is pretty recent.
6 CHAIR KIRCHNER: Our business, I guess, I 7
don't guess, is not to design the system for them.
8 That there are means to control the amounts of fuel 9
that were --
10 MEMBER BALLINGER: Yes.
11 CHAIR KIRCHNER: Mechanical means to kind 12 of safeguard against excessive addition to reactivity.
13 But mechanical systems have been known to fail. They 14 can probably limit the amount of available fuel to be 15 added through different safeguards in mechanical 16 systems. But you still have the potential for the 17 reactivity insertion.
18 MEMBER BALLINGER: It's hard to not try to 19 design the system, because it's probably physically --
20 it's hard from the negative feedback effect that had 21 been there. It's probably impossible to add enough 22 fuel fast enough to have anything bad happen.
23 CHAIR KIRCHNER: Should be, but we haven't 24 seen the design.
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134 VICE CHAIR HALNON: So, if you take, take 1
the non-light-water reactor that we have, you take 2
criticality away from the discussion of whether or 3
not, it's safe or not. You would catch people saying 4
a safe state in the reactors, were basically, I can 5
walk away from it, reduce my control in manning to 6
just the bare minimum, just to keep things running.
7 And not have to worry about, in design basis, or on 8
the basis of that, occurring.
9 MEMBER BALLINGER: That's what NuScale 10 proposed. Long-term cooling, remember, they argued we 11 could have re --
12 CHAIR KIRCHNER: For 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br />.
13 VICE CHAIR HALNON: So, what you've been 14 telling, saying, well in this defined safe state, a 15 licensing based event could still occur? It could 16 cause a problem. And I'm not talking about license, 17 like, you know, I mean like present state and stuff, 18 like that. Even then, external events, a safe state 19 says the reactor is, you don't have to worry about it.
20 You may have --
21 MEMBER PETTI: It's hot, I mean from a 22 temperature perspective. I mean, you'll never get to, 23 quote, "cold shutdown" in any of these of these 24 systems.
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135 CHAIR KIRCHNER: We hope not, any of 1
these.
2 MEMBER PETTI: We don't want to.
3 MEMBER BALLINGER: Let's say that they 4
reduced power to the point where they were just adding 5
heat. In other words, enough heat was being added to 6
keep it from freezing. You know, keep the 7
temperature. Is there some event that could occur if 8
you walked away, that would be a design basis 9
accident?
10 If you reduced the power level to that 11 point, and you couldn't add any more fuel, would the 12 thing, would the negative temperature coefficient just 13 allow it to just sit there adding heat?
14 MEMBER PETTI: Over-cooling events --
15 MEMBER BALLINGER: That's what I was --
16 MEMBER PETTI: -- haven't been this big.
17 I didn't hear anything about safety systems to prevent 18 freezing. And we didn't even go there because we 19 didn't have a lot of design detail. But you know 20 we've raised that with other salt systems. That 21 over-cooling events --
22 MEMBER BALLINGER: That's the thing if 23 they're reduced to adding heat. In other words, 24 you've got enough, you're adding enough heat so 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
136 you can't -- is there some event that can occur that 1
would, you know, take it in a different direction? I 2
don't think so.
3 MEMBER PETTI: Could you get a runaway 4
reactor?
5 MEMBER BALLINGER: Yes. No, I mean --
6 PARTICIPANT: Steam tube generator rupture.
7 MEMBER PETTI: Remember the other designs 8
we've looking at, you have to tie the primary loop and 9
the secondary loop humps together. Otherwise you'll 10 over cool. If the primary trips the secondary has to 11 trip, or you'll over cool. So, there's all sorts of 12 interconnects here in the system that have to be 13 designed in.
14 MEMBER BALLINGER: So, there is an event.
15 MEMBER PETTI: I guess, yea.
16 (Simultaneous speaking.)
17 MEMBER BALLINGER: We don't know any of 18 the details.
19 MEMBER PETTI: But it's not -- it's an 20 over-cooling event. It's not a reactivity event.
21 MEMBER BALLINGER: Over-fueling.
22 MEMBER PETTI: Well, that's what I'm 23 saying, if you had a system where you -- at that 24 point, where you defined yourself as being safe 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
137 is there a way to add reactivity?
1 VICE CHAIR HALNON: And over-cooling is a 2
problem because you have negative NTC.
3 MEMBER PETTI: Yes. And the over-cooling 4
and over-fueling of the ones that, I tend to think.
5 VICE CHAIR HALNON: So, the safe state 6
would be to drive the rods in, shutdown the reaction, 7
and have enough heat so you don't rock it up?
8 MEMBER BALLINGER: But again, like Walt 9
was saying, it's not, we're not here to design the 10 reactor. We just have to tell them that they have to 11 be able to do that, right?
12 VICE CHAIR HALNON: Well, that's at least 13 in our minds we have to agree, what is the adequately 14 safe state. And if we're saying that being critical 15 at some low power level, that where the physics, is 16 the physics taking care of it at a high power level?
17 Physics take care of it at a low power level. So, 18 what --
19 MEMBER PALMTAG: I would argue safe state 20 is subcritical. We have to know, to be --
21 MEMBER BALLINGER: Well, that's for sure 22 a good definition of safe state.
23 VICE CHAIR HALNON: Yes. So, if you're 24 subcritical, then you have to have some kind of heater 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
138 system on salt to --
1 MEMBER PALMTAG: They do.
2 VICE CHAIR HALNON: They will, okay.
3 MEMBER PALMTAG: That's how they have to 4
heat -- they have heat the system up, right. They 5
have to heat --
6 CHAIR KIRCHNER: Will have to balance 7
their heat losses against the, they could use the KE 8
or have to use --
9 MEMBER PALMTAG: Oh, when you start the 10 system up, you have to have heaters. There will be 11 heaters.
12 CHAIR KIRCHNER: Yes. Yes, you'll have 13 heaters.
14 VICE CHAIR HALNON: Well again, I think 15 rather than redesign the process, don't redesign the 16 reactor for them, but just that they're deviating well 17 thought out, probably the best we have, input in front 18 of us at this point of operating experience. PDCs 19 that he didn't use.
20 MEMBER BALLINGER: I'd just say, just 21 comply with the ANS standard unless you can show 22 something else. Unless you justify it.
23 VICE CHAIR HALNON: So, a two-line letter, 24 for the issues.
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139 MEMBER BALLINGER: Yea, well I mean --
1 MEMBER PETTI: Yes. But I still think 2
there's an important principle here. I don't think 3
you can rely on physics until it's demonstrated.
4 MEMBER BALLINGER: That's always the case, 5
yes, right.
6 MEMBER PETTI: That's my bit. I said it, 7
if this was nth of a kind, I would not have that 8
issue. But this is first of a kind. And you have to 9
demonstrate these -- that's why all those damn tests 10 were done back in the day and when we've talked about 11 the role of prototypes and what they do, and why 12 they're so important is that they demonstrated to the 13 NRC at the time.
14 (Simultaneous speaking.)
15 MEMBER PETTI: Look, these systems do have 16 these characteristics. We have tested them.
17 VICE CHAIR HALNON: Well, do you need to 18 have this reactor demonstrate the physics? Or can you 19 do the physics in a test loop of some other type?
20 MEMBER PETTI: No, I mean --
21 (Simultaneous speaking.)
22 VICE CHAIR HALNON: Is it a critical, just 23
-- it's as if --
24 MEMBER PETTI: yes, I don't think you can 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
140 go without thinking those smaller reactors.
1 VICE CHAIR HALNON: I'm thinking, you 2
know, like the ACU reactors that came online before 3
this one, well before.
4 MEMBER PETTI: Yes, but it's a different 5
salt.
6 CHAIR KIRCHNER: Different salt and its 7
size matters.
8 VICE CHAIR HALNON: You're right, I think 9
the size, we thought we're getting --
10 MEMBER PETTI: Yes, the size matters. I 11 mean -- and all we're saying is that for this one, you 12 need a protection system. We're not saying this only 13 needs one from then on. But given the scale of the, 14 I mean all the issues that we talked about in the 15 letter, it's just, it's prudent for this first of a 16 kind.
17 MEMBER PALMTAG: Historically, we scale 18 up, you never go over a factor 10 larger. And they're 19 taking a jump 40 over 70, so I'm, to go to your point 20 and demonstrate this, you usually demonstrate it with 21 the smaller reactor. Let's start with the 40 Megawatt 22 reactor.
23 MEMBER PETTI: As we've seen in other 24 designs, I mean, because we've seen, a classic 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
141 example. It is a configuration and a coolant and 1
moderator, that are unique use together. What they 2
doing? A very small system, work out those kinks, 3
prove things.
4 MEMBER BALLINGER: This is, I'm probably 5
being a heretic but I would consider this unsafe, 6
unless they did a prototype. Sorry.
7 MR. BURKHART: Can I just make an 8
observation on this letter. It sounds like you're, 9
there's a letter there from what you all have just 10 said. Pointing up your observations higher, because 11 you're, it does seem like you're trying to fix the 12 problem, rather than identify the problems, right?
13 MEMBER BALLINGER: That's what I say, just 14 the ANS standard.
15 MEMBER PALMTAG: I don't think just far 16 from that.
17 MEMBER BALLINGER: Huh?
18 MEMBER PALMTAG: I don't think we're far 19 from that.
20 MEMBER BALLINGER: Yes.
21 MEMBER PALMTAG: I mean it's --
22 MEMBER BALLINGER: But it may be that 23 that's like Dave was saying if, that should be a key 24 point, right up front, the key point.
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142 MEMBER PALMTAG: I do have an issue 1
saying, you know, the PDC should have come from the 2
standard, when the standard wasn't finalized yet, 3
right. And they did --
4 MEMBER BALLINGER: But it is now.
5 MEMBER PALMTAG: Yes, but and they did.
6 MEMBER BALLINGER: And they ain't gonna 7
build this for a while.
8 MEMBER PALMTAG: But they do claim that 9
they made their PDCs based on the draft of the ANS 10 standard. So, I don't think the issue is they didn't 11 follow the standard. I think the issue is that they 12 decided to go against the standard, right.
13 MEMBER BALLINGER: Well, why don't we, can 14 we just say that we think there's a better standard?
15 MR. BURKHART: Can I just interject? The 16 NRC has not, from my understanding, endorsed the 17 standard.
18 MEMBER BALLINGER: It's all right.
19 MR. BURKHART: Please keep that in mind.
20 MEMBER PALMTAG: But my understanding is 21 they basically started with the ANS and the 22 proprietary version of 1.232 that we can't say aloud.
23 And then they said, here's the exceptions that we're 24 going to take. And it's the exceptions that we're, 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
143 have concerns with. Not that they didn't start with 1
the standard.
2 MEMBER BALLINGER: The other problem is 3
this went through the Canadian system, right?
4 MEMBER PALMTAG: Yes.
5 MEMBER BALLINGER: And they approved it.
6 In whatever the heck they, by whatever --
7 VICE CHAIR HALNON: It was only their 8
level one --
9 MEMBER PALMTAG: Level one and level two, 10 which I don't know what that means.
11 MEMBER BALLINGER: Yes. I don't know what 12 that means either, but somebody said that it was okay.
13 MEMBER PALMTAG: Yes, but --
14 MEMBER SUNSERI: It's essentially a 15 construction permit type review.
16 MEMBER PALMTAG: I don't even know if it 17 was that far.
18 MEMBER PETTI: Yes, but again, remember 19 CANDUs are a lot positive coefficients that would not 20 be --
21 CHAIR KIRCHNER: They redesigned it.
22 MEMBER PETTI: They redesigned them.
23 CHAIR KIRCHNER: They took that away.
24 MEMBER PETTI: But at that time.
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144 CHAIR KIRCHNER: Yes.
1 MEMBER PETTI: Right, that was a big 2
difference of the two, it was two systems, the 3
regulatory systems. So, what I'm -- let's see if I 4
can move this along. Is if we took this paragraph in 5
blue and that became our second paragraph in the 6
discussion.
7 MEMBER PALMTAG: I think we have this 8
duplicated don't we, to say basically, we don't 9
specifically call out the ANS standard but we have 10 these points.
11 MEMBER PETTI: Right, yes. But just let 12 me complete the thought. You'd have a paragraph on 13 what the standard is. That was all put in there for 14 the last sentence, which needed a context, which is 15 the fueling system has to have, because it's a 16 reactivity addition system, has to have some sort of 17 controls.
18 And if that's consistent with the crime, 19 it's the sin. So, what we could do is we could just 20 say, this what the standard is. Then we could talk 21 about reactor control, and we can talk about the 22 fueling system. Then we could talk about reactor 23 shutdown.
24 MEMBER BALLINGER: It's referencing --
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145 MEMBER PETTI: And I think we can get rid 1
of the paragraph on two independent means because they 2
do have two independent means. We just are not, you 3
know.
4 MEMBER PALMTAG: We could do that, we 5
could start over. Or we could try to fix this.
6 MEMBER BALLINGER: Is the reference to the 7
ANS standard one of the results and conclusions, one 8
of the conclusions and recommendations. If it's not, 9
it should be.
10 PARTICIPANT: Well, again we haven't --
11 MEMBER PALMTAG: No, but we've said that 12 those, we've made those four recommendations in here, 13 or we've made the recommendations that do agree with 14 the ANS standard. But again, the ANS standard --
15 well, there's two things. The ANS wasn't completed 16 and second, I mean, Larry brought up a good point that 17 NRC hasn't endorsed that. I don't know if that's, we 18 want to make that a requirement.
19 VICE CHAIR HALNON: The one you didn't, 20 number three touches on it, but doesn't say ANS. It 21 just says it eliminates several of design criteria, 22 used in other reactor designs.
23 MEMBER PALMTAG: Yes, that could be easily 24 modified, to put in the ANS.
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146 MEMBER PETTI: Again, I think we've got to 1
get the letter right before, I think the conclusions 2
will fall easily once we get a logic in the letter, 3
the flow of the letter correct.
4 CHAIR KIRCHNER: Well, just one Member's 5
opinion. I cannot imagine a power reactor out there 6
in the fleet that doesn't have a protection system.
7 MEMBER PETTI: Duh.
8 CHAIR KIRCHNER: And I don't know how 9
their condition would go forward with that and gain 10 any public confidence in deployment of these systems.
11 It's humorous almost, on our part, to say that we can 12 look ahead to something that's scaling a factor of 100 13 in terms of power versus the MSRE reactor, which 14 didn't operate very long by the way.
15 MEMBER PETTI: And didn't have the power 16 conversion system.
17 CHAIR KIRCHNER: Right. And it was much 18 smaller in terms of neutronic behavior. Very leaky 19 system. The idea of not having a protection system to 20 sense accident conditions and initiate operations of 21 systems and components important to safety, to me, is 22 just, I don't think --
23 MEMBER BALLINGER: Unless they had a proto 24 CHAIR KIRCHNER: -- it's just incredible.
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147 MEMBER BALLINGER: Unless they have a 1
prototype that demonstrates all that.
2 CHAIR KIRCHNER: Even if you have a 3
prototype, I mean, you're presuming that you now know 4
so much about this reactor, that you're not going to 5
get into a condition where you don't have a reactivity 6
insertion and an over-power or whatever as a result.
7 This, that's a big leap. It's an awfully big leap.
8 It sounds like an experimental reactor to me. Not a 9
power production reactor.
10 MEMBER BIER: I think I agree with Walt.
11 Many years ago when I an assistant professor, I was 12 arguing that passively safe reactors may need to have 13 some active systems just to guard against, what if we 14 don't understand all the phenomena properly.
15 And, you know, I think Dave's comment 16 about, okay, once you get to nth of a kind, and you 17 have, you know, some years of operating experience, 18 and various off normal conditions observed. Maybe you 19 can get there. But it's, you know, I don't know the 20 physics to know how well it's understood. But it 21 seems questionable to me that we can know it that 22 well.
23 CHAIR KIRCHNER: Well, it's right there on 24 line 130. Do they need a protection system or not?
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148 And that would require essentially a safety grid 1
instrumentation and control system to implement it.
2 VICE CHAIR HALNON: Okay. Well, so first, 3
so rather than we sit here and concentrate on it for 4
a while, if we answer that first question, and Scott's 5
starting to put it out there. Is the safe state, does 6
it have to be subcritical? If the answer to that is 7
yes, then I think the answer to this is, yes.
8 That you have to have some kind of 9
protection system to shut it down, because then 10 physics will not do it. So, if we accept, just to 11 move it forward, Scott's discussion about we make the 12 statement that a safe state has to be subcritical.
13 One way of getting this, was subcritical is to have a 14 protection system that shuts it down.
15 MEMBER PALMTAG: So, let me just, number 2, 16 could we look at number 2.
17 VICE CHAIR HALNON: Right.
18 MEMBER PETTI: So, I should, Larry just 19 sent us the us the Executive Summary.
20 MEMBER BALLINGER: Yes, that's pretty darn 21 good.
22 MEMBER PETTI: Page 2, review.
23 MEMBER BALLINGER: Yes.
24 MEMBER PETTI: Number 4, the capability, 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
149 and effectiveness of the proposed means of reactor 1
control and shutdown needs to be further demonstrated.
2 Particularly the reliance on the overall negative 3
temperature reactivity coefficient. The negative 4
coefficient will need to be verified for all 5
conditions and circumstances to help support the 6
proposed design for reactor shutdown.
7 So, that means the same, the same thing, 8
you know.
9 MEMBER BALLINGER: Ah, look at number 7.
10 (Pause.)
11 MEMBER BALLINGER: Here you go.
12 CHAIR KIRCHNER: Are you referring to the 13 SER?
14 MEMBER PETTI: No, this is the Canadian.
15 the Canadian, executive --
16 MEMBER BALLINGER:
Because they're 17 basically saying exactly what we're saying in a 18 sentence.
19 MEMBER PETTI: In a less direct -- in a 20 maybe a more politically correct way than we are. But 21 what I'm worried about is because all of this 22 proprietary. I really think we need to be as direct 23 as we can in our letter. Because it will be the only 24 thing on the record. If you read the staff's SE, you 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
150 can't tell what's really going on, because there's so 1
much proprietary stuff.
2 MEMBER BALLINGER: Yes, we're lucky that 3
Walt wasn't here during the presentation. We would 4
have had to have blood pressure medicines mainlined in 5
him.
6 CHAIR KIRCHNER: We could have proprietary 7
discussions.
8 MEMBER BALLINGER: So, what, should I try 9
to drive and see if this helps?
10 CHAIR KIRCHNER: Let me do a check with 11 my, do we still have the Court Reporter?
12 VICE CHAIR HALNON: Yes, we should 13 probably cut him loose him, yes.
14 CHAIR KIRCHNER: We should let the Court 15 Reporter go, because we are now in letter writing --
16 MR. BURKHART: Although I think what 17 they're capturing is very, very good.
18 CHAIR KIRCHNER: No, this was intentional 19 that they do capture our conversation.
20 MR. BURKHART: Okay.
21 CHAIR KIRCHNER: All right, with that, 22 it's Jim, right?
23 COURT REPORTER: James.
24 CHAIR KIRCHNER: James, I think we can 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
151 dispense with the transcription for the rest of this 1
afternoon. And we'll need you back tomorrow afternoon 2
at 1:00 p.m. Eastern time. We hear about the ADVANCE 3
Act from Mike King.
4 Okay, thank you.
5 (Whereupon, the above-entitled matter went 6
off the record at 2:06 p.m.)
7 8
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