ML18149A563
| ML18149A563 | |
| Person / Time | |
|---|---|
| Issue date: | 04/05/2018 |
| From: | Advisory Committee on Reactor Safeguards |
| To: | |
| Wang W, ACRS | |
| References | |
| NRC-3627 | |
| Download: ML18149A563 (119) | |
Text
Official Transcript of Proceedings NUCLEAR REGULATORY COMMISSION
Title:
652nd Meeting Advisory Committee on Reactor Safeguards (ACRS) - Open Docket Number:
N/A Location:
Rockville, Maryland Date:
April 5, 2018 Work Order No.:
NRC-3627 Pages 1-102 NEAL R. GROSS AND CO., INC.
Court Reporters and Transcribers 1323 Rhode Island Avenue, N.W.
Washington, D.C. 20005 (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 652nd MEETING 4
ADVISORY COMMITTEE ON REACTOR SAFEGUARDS 5
(ACRS) 6
+ + + + +
7 OPEN SESSION 8
+ + + + +
9 THURSDAY 10 APRIL 5, 2018 11
+ + + + +
12 ROCKVILLE, MARYLAND 13
+ + + + +
14 The Advisory Committee met at the Nuclear 15 Regulatory Commission, Two White Flint
- North, 16 Room T2B1, 11545 Rockville Pike, at 1:30 p.m., Michael 17 Corradini, Chairman, presiding.
18 COMMITTEE MEMBERS:
19 MICHAEL L. CORRADINI, Chairman 20 RONALD G. BALLINGER, Member 21 DENNIS C. BLEY, Member 22 CHARLES H. BROWN, JR., Member 23 MARGARET SZE-TAI Y. CHU, Member 24 VESNA B. DIMITRIJEVIC, Member 25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.
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2 WALTER L. KIRCHNER, Member 1
JOSE MARCH-LEUBA, Member 2
DANA A. POWERS, Member 3
HAROLD B. RAY, Member 4
JOY L. REMPE, Member 5
PETER RICCARDELLA, Member 6
JOHN W. STETKAR, Member 7
MATTHEW W. SUNSERI, Member 8
9 DESIGNATED FEDERAL OFFICIAL:
10 GIRIJA SHUKLA 11 12 ALSO PRESENT:
13 CLINT ASHLEY, NRO 14 AMY CUBBAGE, NRO 15 DON HABIB, NRO 16 ZACHARY HARPER, Westinghouse 17 WILLIAM RECKLEY, NRO 18 SHAYAN SINHA, Westinghouse 19 BOYCE TRAVIS, NRO 20 21 22 23 24 25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.
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3 TABLE OF CONTENTS 1
PAGE 2
Advanced Reactor Functional Containment 3
SECY Paper 4
4 5
WCAP-17938-P, Revision 2
............ 83 6
7 8
9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.
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4 P-R-O-C-E-E-D-I-N-G-S 1
(1:30 p.m.)
2 CHAIRMAN CORRADINI: Okay. Why don't we 3
get started. So our first topic of the afternoon is 4
review of the draft SECY paper on functional 5
containment performance criteria for non-light water 6
reactor designs. And our illustrious speaker is Bill 7
Reckley. Bill? Well, he's all yours. Oh, I'm sorry.
8 Excuse me. I apologize. I first should turn it over 9
to the Chairman of the Subcommittee, Dr. Bley.
10 MEMBER BLEY: Thank you, Mr. Chairman.
11 CHAIRMAN CORRADINI: I apologize. I'm 12 sorry.
13 MEMBER BLEY: Well, that's okay. Well, 14 he'll lead us through this, I apologize. We're going 15 to hear more, and, Bill, I guess you have a part on 16 here where you're going to tell us about any changes 17 that have been submitted since the last time we talked 18 with you. I think almost all the members who were 19 here at the subcommittee are here now.
20 So we look forward to hearing what you 21 have to say, and okay.
22 MR. RECKLEY: Thank you. As Dr. Bley 23 mentioned, what the staff will be looking for out of 24 the day is a letter on the SECY. We did provide a 25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.
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5 redline strikeout that was --
1 MEMBER POWERS: For the letter?
2 (Laughter.)
3 MEMBER BLEY: No, sir. They didn't give 4
us a draft letter.
5 (Laughter.)
6 MR. RECKLEY: It's funny that you mention 7
that because among the things we have talked about, 8
the staff would offer up to write your letters.
9 (Laughter.)
10 MR. RECKLEY: If you were willing to start 11 with the letter the staff wanted, we would -- we would 12 offer to draft it for you, so --
13 MEMBER POWERS: And why -- and what 14 deterred you on this? Obviously --
15 MR. RECKLEY: No, I'm saying that as a 16 joke.
17 MEMBER POWERS: -- a very perspicacious 18 undertaking.
19 MR. RECKLEY: We did provide a redline 20 strikeout version, but there weren't very many changes 21 to the -- to the draft SECY that we had talked about 22 during the subcommittee meeting.
23 I'll go a little faster today than we did 24 during the subcommittee, so some of this I'll just 25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.
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6 largely skip over. I will -- I will touch on 1
background, and then we'll get into the structure of 2
the paper and a couple of the key topics like the 3
relationship to Reg Guide 1.232 on advanced reactor 4
design criteria.
5 I will mention that was actually issued on 6
Tuesday, so it's finalized and released. It ties in 7
closely with the efforts we currently have underway 8
with the licensing modernization project, and we are 9
on ACRS Subcommittee schedules, at least tentatively, 10 for June and October, and hopefully maybe a full 11 committee meeting in December on the guidance that is 12 being developed there. And, again, I'll touch on the 13 relationship to that.
14 This gets a little complicated because 15 we're trying to develop a licensing framework, if you 16 will, and so we're bringing pieces to you today on --
17 on functional containment performance criteria, but 18 we'll explain how it fits into the longer term effort.
19 But we just thought it was necessary to try to resolve 20 this long-standing issue, so that we could free up, if 21 you -- if you will.
22 As we go through
- this, the more 23 uncertainty there is in terms of our degrees of 24 freedom to work within, the harder it is or easier it 25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.
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7 is to work out a framework. If -- if anyone is going 1
to tell us this is fixed, you cannot -- this is a 2
parameter or this is a regulatory area that's fixed, 3
you can't propose any revisions, then we have to 4
develop the whole framework around that.
5 So as I'll get into later, what we're 6
largely looking to do here is make sure that 7
functional containment is in play, along with 8
everything else associated with advanced reactor 9
designs.
10 MEMBER BLEY: Bill, you set up the 11 question for me there. As I read the second enclosure 12 and look for performance criteria, it seems that what 13 you're really doing is asking the Commission to 14 continue what they told you to do some years ago and 15 develop those criteria. I don't see any real criteria 16 set up already.
17 MR. RECKLEY: There won't. And as I'll 18 talk about -- and even actually on the next bullet, we 19 tried to -- to make a couple changes to the language 20 to emphasize that this paper is laying out a 21 methodology.
22 MEMBER BLEY: Okay.
23 MR. RECKLEY: Doesn't lay out criteria in 24 terms of a leak rate or some other physical parameter.
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8 It lays out a methodology, and so I'll touch on that 1
some more.
2 One of the reasons that we think that's as 3
far as we can go in order to support the developers at 4
this time is on the background slide, the one down in 5
the -- in the corner that was included in the status 6
paper, SECY-18-0011, but it just lays out the number 7
of different technologies and sizes of reactors that 8
are in play.
9 And we're striving to come up with one 10 framework that can address any of these non-light 11 water reactors, ranging from potentially less than a 12 megawatt micro-reactor or mini-reactor, whatever 13 terminology one wants to use, up to more full-scale 14 hundreds of megawatt
- plants, and ranging in 15 technologies from liquid metal to gas-cooled to molten 16 salt or -- or the fluoride high-temperature reactors.
17 So all of those, we're trying to come up 18 with a methodology or approach that will work for any 19 of those designs, the technology-inclusive approach.
20 So that's the landscape slide that we used in the SECY 21 paper to show all the different designs and sizes and 22 technologies in play.
23 The other thing in terms of background is 24
-- and we have come and talked to the ACRS in the past 25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.
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9 about our vision and strategies for addressing non-1 light water reactors, and our implementation action 2
plans and the various strategies in play, and then, 3
again, I'll mention that all of that is summarized in 4
a relatively recent Commission paper, SECY-18-0011, 5
Advanced Reactor Program Status.
6 So the rest of this presentation will talk 7
about one area, which is an issue that was resolved, 8
was identified in terms of functional containment.
9 And then, as I mentioned, everything in highlight 10 there is in play on this particular issue, the policy 11 issues under strategy 5, and the licensing framework 12 under -- under strategy 3, in our implementation 13 action plans.
14 So just quickly on the format or layout of 15 the paper, the paper is a summary of the two 16 enclosures, and the two enclosures are, one, a 17 background, and then number two, the paper that 18 describes the approach or methodology for any 19 particular non-light water reactor design to define 20 for themselves the performance criteria for a 21 functional containment.
22 So in terms of Enclosure 1, which I'm not 23 going to talk a lot about here because it was -- it 24 just basically provides background, the key documents 25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.
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10 are the terminology "functional containment" and issue 1
was brought before the Commission in the -- in the 2
paper SECY-93-092, one of the earlier papers on issues 3
for advanced reactor designs following the development 4
of the advanced reactor policy statement and the 5
receipt of some preliminary designs, such as SAFR and 6
PRISM and the MHTGR in the late '80s and early '90s.
7 That paper basically had the Commission 8
agree that a functional containment was -- could be 9
thought of as in lieu of a pressure-retaining 10 containment like is used for light water reactors.
11 The staff came back to revisit that in SECY-0347. And 12 the Commission said it was a little premature at that 13 time, given the state of the development of the -- of 14 the reactors, to make a final decision, but asked the 15 staff to come back with performance criteria.
16 We come back -- there is about a decade 17 gap. As we go through these periods of interest and 18 waxing and waning of advanced reactor programs, we 19 come back in the -- in the 2000s, under the NGNP, Next 20 Generation Nuclear Plant. And, again, functional 21 containment is one of the key licensing issues for 22 that project.
23 The staff, even at that time, comes and 24 presents to the ACRS and sends a letter to DOE 25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.
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11 summarizing where we are. Again, emphasizing, we 1
think, functional containment as a concept is okay, 2
and -- but not fully resolving what the performance 3
criteria would be for -- for the functional 4
containment.
5 We revisit most recently again in Reg 6
Guide 1.232 the advanced reactor design criteria.
7 Again, the staff had several meetings with ACRS on 8
that topic, and we -- and we did issue that on 9
Tuesday.
10 That reg guide reflects within the high 11 temperature reactor -- high temperature gas reactor 12 technology, the MHTGR design criteria, basically the 13 concept of functional containment and the performance 14 criteria that was laid out for NGNP. For the generic 15 or non-technology-specific advanced reactor design 16 criteria, we basically stuck, as you are aware, with 17 the existing general design criteria.
18 But there is terminology within the reg 19 guide that says another technology like molten salts 20 may want to look at the design criteria established 21 either for fast reactors, or in this case the MHTGRs 22 for functional containment concepts. And the reg 23 guide points out that there is a remaining policy 24 issue which this paper is intended to -- to resolve.
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12 But just, again, going kind of through the 1
format of the enclosure, it simply starts out why 2
we're addressing this at this time within the paper.
3 It addresses strategy 3, the regulatory framework for 4
non-light water reactors; and strategy 5, the 5
identification and resolution of technology-inclusive 6
policy issues.
7 I'll just leave it there. I think we 8
talked about that last time. But that's -- what we're 9
trying to do within -- within the framework and within 10 strategies 3 and 5, as well as all of the strategies, 11 to be honest, but we're probably a little further 12 along in strategies 3 and 5 to say how we're trying to 13 develop an integrated approach to support the 14 developers or designers of these non-light water 15 reactors.
16 That community is -- is a very diverse 17 community in terms of it ranges from very established 18 long-standing companies that have designed, built 19 reactors, gone through licensing processes, and so 20 forth.
21 It also includes some much smaller 22 companies trying to take maybe a more entrepreneurial 23 approach to this. They're relatively small. They're 24 trying to fund it through a combination of private 25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.
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13 capital and, where possible, maybe some support, 1
technical or financial, from the Department of Energy.
2 But a little different in terms of what 3
they're asking the NRC to do is to interact earlier in 4
the process. So even in the conceptual or preliminary 5
design processes, to interact with the NRC to -- to 6
make sure they're on the right track because the 7
complaint has historically been that regulatory 8
uncertainty is resolved at the eleventh hour, but the 9
financial investment by the eleventh hour has already 10 been substantial.
11 And so the general complaint was to try to 12 reduce the regulatory uncertainty kind of in a line 13 going down as the cost escalated. And so that -- that 14 really did call for us to take this more integrated 15 approach.
16 We tried -- we have tried to represent 17 that using this bowtie diagram where you map out under 18 this approach the threats as identified on the -- on 19 the left, the plant -- and these are just the 20 traditional segregation of events, plant, internal 21 events, external events, and then malicious acts.
22 And any of those can lead to the plant 23 damage state or could potentially lead to a plant 24 damage state where you start to get the migration of 25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.
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14 radionuclides or fission products from the core or, in 1
the case of a molten salt, at least out of the 2
configuration they are intended to be in.
3 So in terms of the light water community, 4
this -- this fits very well. The top-level event is 5
core damage, and -- and you have a whole bunch of 6
measures that are taken to prevent it, and you have 7
defined severe accident design features, emergency 8
planning, siting restrictions, a number of things on 9
the mitigation or recovery side of the bowtie diagram.
10 So --
11 MEMBER POWERS: You say the concern is 12 core damage.
13 MR. RECKLEY: The methodology allows you 14 to define whatever top-level event you really want to 15 concern yourself with. I would say traditionally in 16 light water reactors we have defined the top-level 17 event in most of the things we do as significant core 18 damage -- core melt.
19 MEMBER POWERS: I mean, it seems to me 20 that that's -- that's the faux pas in looking at these 21 unusual reactors. It seems to me that you really end 22 up having to say it's radionuclide releases, and then 23 you come to a debate, is it radionuclide releases from 24 boundary 1 or boundary 2 or outside the exclusion 25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.
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15 area? That's where the debate is.
1 For instance, we have molten salt reactors 2
that really don't have a defined core. And you have 3
various overly optimistic individuals in the gas 4
reactor community that says, "Our core doesn't get 5
damaged."
6 I
- mean, don't you want to just 7
automatically say, "We're going to quit doing this 8
core damage thing" and start
- saying, "It's 9
radionuclide release," and we will debate which 10 boundary we -- we draw the line at, because I don't 11 know what it -- you know, I don't know where it is, 12 but, I mean, I -- I would think that that's -- that's 13 almost required in this context.
14 MR. RECKLEY: And you can do it. And I'll 15 be honest, the first time I -- the first time I drew 16 the bowtie my top-level event was radiological release 17 as opposed to core damage or some rough equivalent, 18 which I came up with the language of unplanned 19 migration of fission products because, again, that's 20 not core damage or core melt per se. It's just a loss 21 of control of the radioactive material within its 22 normal state or configuration.
23 The reason I ultimately changed it was to 24 better -- actually to better align it with traditional 25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.
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16 approaches and, for example, the IAEA five levels. If 1
you say radiological release, you're almost by -- your 2
top-level event is already at level 4 or 5.
3 And traditionally in the IAEA language, 4
mitigation is the things you take like a core spreader 5
or a core catcher or other severe accident design 6
feature is usually a mitigation measure on the right-7 hand side of this diagram, on the mitigation side.
8 So I was trying to align it. You could 9
draw it exactly as you're describing it. I mean, the 10 methodology lets you define whatever top-level event.
11 I was trying to align it with more in line with the 12 light water reactor and IAEA standard five levels in 13 which you would have more than just emergency planning 14 as a mitigation measure.
15 You would have -- are you going to do 16 something other than emergency planning, like a severe 17 accident design feature on the light water reactor 18 side.
19 MEMBER MARCH-LEUBA: Focusing on what 20 we're doing today, which is reviewing the functional 21 containment --
22 MR. RECKLEY: Right.
23 MEMBER MARCH-LEUBA: -- the function of 24 the containment is to prevent radioactive release even 25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.
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17 in the core.
1 MR. RECKLEY: Right.
2 MEMBER MARCH-LEUBA: So if you remove that 3
function, then you don't need a containment. So if 4
you are willing to limit yourself to I will never melt 5
the core --
6 MR. RECKLEY: And one of the reasons I 7
actually kind of -- I like the bowtie diagram is, if 8
you look, it considers not only the damage state but 9
the extent of the hazard.
10 So when you get, for example, to a very 11 small reactor or potentially as a fuel form where a 12 loss of the normal safety functions, like cooling, 13 does not lead to radioactive materials going airborne 14 or in some other releasable form, then your top-level 15 event really doesn't have much consequence, and you 16 wouldn't need all of the mitigation measures on the 17 other side.
18 I compare it to if you have, either 19 because of its size or a technology, that a power-20 producing device that were treated as the reactor, is 21 as safe as a radiography machine in terms of it's a 22 threat. I mean, there's radioactive material there.
23 It's not as if you can ignore it, but it doesn't 24 require things to keep it safe, other than shielding.
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18 If you had a reactor that was as safe as 1
that, then you wouldn't need all of those things.
2 You'd need shielding, but you wouldn't need all of 3
these emergency functions.
4 And this -- this -- I don't want to 5
overstate the usefulness of the representation, but it 6
lets you take into account the hazard in terms of the 7
source term, the amount of radioactive material you 8
are dealing with.
9 But, again, to Dr. Powers' point, it's --
10 this is a way to draw it. I wouldn't say it's the 11 only way to draw it, but it does -- it does let you 12 define those actions or barriers or controls, whatever 13 structures, systems, and components that you're 14 putting into the design to keep the radioactive 15 material in place, and those things that you might add 16 if you lose control of it, assuming that the loss of 17 control puts it in a form that might be releasable.
18 So --
19 MEMBER MARCH-LEUBA: This is a little bit 20 of semantics. Whether you call the containment a blue 21 prevention, it prevents the radionuclides from 22 leaving, or you call it a mitigation after it melts 23 the core is the same thing.
24 MR. RECKLEY: I don't disagree with you.
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19 It just -- it's an accounting measure. It doesn't 1
result in any difference in terms of --
2 MEMBER MARCH-LEUBA: And also there will 3
4 MR. RECKLEY: So, but what it allow us to 5
do, going back to the integrated activities, is what 6
we were trying to make sure -- and this is more 7
applicable perhaps to some of the early developers or 8
less experienced developers, to make sure they were 9
thinking about the total -- the total picture.
10 That two -- and this is the way light 11 water has actually evolved, and that was because we 12 were learning and imposing additional restrictions as 13 we went along. But to make sure we incorporate all of 14 those lessons learned, all of those activities into 15 the initial design.
16 And one example is if I'm -- an easy 17 example on the structural side is if I'm going to have 18 a wall that is providing my wind protection, tornado 19 or hurricane protection, I don't want to go way into 20 the design and then decide later on now I'm going to 21 do my aircraft impact assessment and find out the wall 22 is not thick enough.
23 I want to take an integrated look at my 24 design as I'm going through the process and say, "What 25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.
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20 am I going to credit for external events? What am I 1
going to credit for security? What am I going to 2
credit for aircraft impact?" And come up with the 3
best design. And from a designer standpoint, the more 4
you can take credit for the same thing for multiple --
5 for multiple external hazards or internal events, the 6
better in terms of the simplicity of the design.
7 So that's just laying out the backdrop.
8 And then, on the consequence side, also look at it for 9
all the regulatory decisions that we need to make, not 10 only health effects but also the societal and 11 environmental decisions that we need to -- to make 12 during the review.
13 So I mentioned how this plays into the 14 ARDC. You just had a recent meeting on this, but this 15
-- this slide defines for design criteria 16 for the 16 modular high-temperature gas reactor, MHTGR, and you 17 can see that the term "functional containment" is 18 included and defined, and the definition is there.
19 It can be a barrier or set of barriers 20 taken together that limitly effect -- or effectively 21 limit the physical release of radionuclides for all of 22 the event categories. And we're going to get to that 23 in the next slide or two.
24 MEMBER MARCH-LEUBA: I don't have any 25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.
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21 problem with your definition of functional containment 1
or the use of a functional containment. As long as it 2
functions and it retains radioactivity, it's a good --
3 it's a good containment.
4 But, however, I have a problem with the 5
previous paragraph. In the write-up, you say that to 6
accommodate defense-in-depth will require multiple 7
barriers. I would have liked to say that there are 8
multiple independent barriers, be specific about it, 9
because if the failure of barrier 1 automatically 10 fails barrier 2, you will have multiple barriers.
11 MR. RECKLEY: Right.
12 MEMBER MARCH-LEUBA: So we need to be more 13 specific in saying that when we -- when we say 14 multiple barriers, we mean multiple independent 15 barriers.
16 MR. RECKLEY: Okay.
17 MEMBER MARCH-LEUBA: Definitely I would 18 like to call them diverse also, but I won't push it 19 that hard.
20 MEMBER POWERS: I'll echo here, and say it 21 should be multiple independent barriers of increasing 22 conservatism.
23 MEMBER MARCH-LEUBA: That's the way it 24 used to be. It doesn't need to be that. I mean, you 25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.
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22 have a very good one at the beginning. I don't see 1
the increasing concern about this and being a 2
requirement. Multiple independent, I think it is.
3 MEMBER BLEY: Independent under what 4
condition?
5 MEMBER MARCH-LEUBA: That's the --
6 MEMBER BLEY: See, we thought we had 7
independent barriers, and then we had PWR-1 and we 8
found out the same thing that broke the core broke the 9
containment.
10 MEMBER MARCH-LEUBA: Yeah.
11 MEMBER BLEY: And we said, "Gee, they're 12 not so independent." And any set of barriers will be 13 not independent under some external insult if it's big 14 enough. So, you know, we dream of independence, but 15 we don't get it ever.
16 MEMBER MARCH-LEUBA: Yeah. But we should 17 at least try.
18 MEMBER BLEY: We can try, but when we say 19 it must be independent, it never is.
20 MEMBER MARCH-LEUBA: You put a call 21 related to it.
22 MEMBER STETKAR: No. Because when you say 23 "independent," they are truly independent. That's the 24 problem -- that's the dichotomy that you run into, 25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.
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23 that you will find people who say unless there is 1
precisely a zero percent joint probability of their 2
failure, they are not independent.
3 MEMBER MARCH-LEUBA: So because they have 4
10 to the minus 6 probability --
5 MEMBER BLEY: No.
6 MEMBER MARCH-LEUBA: -- they won't be 7
independent, we give up?
8 MEMBER BLEY: No. But --
9 MEMBER STETKAR: You characterize it --
10 MEMBER BLEY: -- you get yourself in a box 11 when you say they must be independent and you can't do 12 it. So as independent as possible, independent 13 under --
14 MEMBER STETKAR: Not linked functionally.
15 Something like that, such that a single --
16 MEMBER BLEY: And that's really where I 17 think --
18 MEMBER STETKAR: -- failure of a single 19 function --
20 MEMBER BLEY: -- Jose, you were coming 21 from, is that they are -- they are not linked 22 internally such that one automatically fails the 23 other. And that's okay. I mean, that's something we 24 want.
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24 MEMBER MARCH-LEUBA: I have serious --
1 MEMBER BLEY: That we can do.
2 MEMBER MARCH-LEUBA: I have serious 3
problems in that I -- let's pick up in one of these 4
sites. With two of the barriers -- two of the other 5
barriers are within a millimeter of each other and 6
enclosed by a burnable material?
7 MEMBER BLEY: Then an earthquake will 8
break them when they bang together.
9 MEMBER MARCH-LEUBA: Yeah. You're never 10 going to be perfect, but removing the -- at least the 11 goal, making them as independent as possible --
12 MEMBER BLEY: We've heard from some of us 13 and from other people, once we define something, then 14 we think we have to meet the definition, absolutely.
15 And that gets us into --
16 MEMBER MARCH-LEUBA: Let's define --
17 MEMBER BLEY: -- silliness, a word I heard 18 earlier today.
19 MEMBER MARCH-LEUBA: Let's define it 20 properly. But giving up the goal of independence 21 because you cannot achieve it perfectly is not --
22 MEMBER BLEY: Would be silly.
23 MEMBER MARCH-LEUBA: That would -- well, 24 that's what we're doing. We're being silly.
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25 MEMBER BLEY: No, I don't think so.
1 MEMBER MARCH-LEUBA:
With those 2
independent --
3 MR. RECKLEY: Okay. We did add -- and 4
we'll get -- we'll get to it later and we'll see -- we 5
tried to add something. We'll see if it's -- it's 6
enough to scratch your itch.
7 The other thing I'll mention is that we 8
will revisit this in the June and October meetings, as 9
we talk about the overall framework and the 10 incorporation of defense-in-depth as a specific 11 activity or process within that framework in order to 12 do not only the containment design but all of the 13 safety functions really that are -- that are 14 associated with -- associated with reactors.
15 And so I'm not trying to punt all 16 together, but the concept of defense-in-depth and 17 independence, and so forth, we can come back in a more 18 general sense under the framework discussions that 19 we'll -- that we'll have. So --
20 MEMBER KIRCHNER: Bill, before you go 21 on --
22 MR. RECKLEY: Yeah. I'm not --
23 MEMBER KIRCHNER: -- of the three choices 24 you could have made, I know that implied behind the 25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.
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26 functional containment is the HTGR design and the 1
unique design aspects and challenges they have for 2
certain events, design basis events and postulated 3
accidents.
4 And blowdown gives them a particular 5
challenge. It's really an economic challenge. It 6
would be very expensive to build a building that could 7
be essentially leak-tight against a blowdown of a 8
high-pressure helium system of that size. But I 9
wanted to go back to -- so you're going forward with 10 the HTGR advanced reactor design criterion as the 11 basis for functional containment.
12 But as we went through previously, and 13 Dana mentioned early on, it -- it does imply, because 14 you change an important word from the more generic 15 advanced reactor design criteria, and that is you go 16 from uncontrolled release, essentially a leak-tight 17 barrier against uncontrolled release, to one that 18 provides a controlled release, and that begs the 19 question of -- I know you said you're not going to 20 have the metric in this paper. That I guess would 21 come later, but it -- it really refers you back to 10 22 CFR 50.34 for offsite dose consequence limits.
23 So that -- that would come in conjunction 24 with your definition down the road when you --
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27 MR. RECKLEY: Yeah. It actually got --
1 well, let's go to the next slide. The approach will 2
be to have event categories. And so for most of the 3
time, if you -- if you're going to be talking about 4
ultimately the blow of containment to limit the public 5
dose, the performance criteria is going to be for 6
design basis accidents or design basis events in that 7
middle category of frequency -- it's going to be the 8
50.34 limit.
9 MEMBER KIRCHNER: Limit.
10 MR. RECKLEY: As you get lower in 11 frequency into the beyond design basis event, it ends 12 up being the safety goals that -- that establish the 13 performance criteria.
14 The other line on this slide that becomes 15 important is the EPA, Environmental Protection Agency, 16 Protective Action Guidelines dose guidance levels at 17 one rem. And you will hear in the future about a 18 general goal which has existed all along for 19 Generation IV reactors to not rely on offsite 20 emergency planning as much.
21 And so most -- I'll get in trouble. Some 22 designs, many designs, are establishing as a goal that 23 they won't exceed the protective action guidelines 24 beyond the fence, 400 meters, 800 meters, such that 25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.
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28 the offsite emergency planning provisions of alert 1
notification, drills, evacuations, all of those things 2
can be relaxed.
3 So to the degree that a design strives to 4
reduce the offsite emergency planning, the performance 5
criteria could be much lower than the 50.35 number.
6 But assuming that they keep the existing requirements 7
in terms of offsite emergency planning, it would be 8
the 50.34 number or the safety goal if it's dealing 9
with sequences much lower in -- in frequency.
10 So, but the introduction of this frequency 11 consequence target figure within the paper is in large 12 part just to describe the general framework. And this 13 is -- this is not really new, and it's -- it's not 14 dramatically different than light water reactors, if 15 you look at some of the later ANS standards that adopt 16 event conditions or event categories based on 17 frequencies.
18 Most of the light waters were -- were 19 actually licensed before that version of the ANS 20 standard. But it's not -- it's not a new -- not a new 21 concept, and so basically -- and the categories will 22 found familiar, anticipated operational occurrences, 23 design basis events are the middle category, and then 24 beyond design basis events.
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29 MEMBER BROWN: Before you go -- go back to 1
the other one again. I guess I'm still struggling --
2 and this follows from the previous meeting that we 3
had. I'm echoing Walt a little bit, and we've gone 4
from some specificity in terms of when we did the 5
advanced reactor design stuff to meet the 10 CFR 6
whatever it is, 50.34. But yet this goes to the point 7
that we're going to control it to ensure conditions 8
important.
9 But there is no -- there is no illusion or 10 no alluding to some type of criteria, not even a more 11 generic criteria such as onsite/offsite exposures as 12 defined by the Commission, or something that's not 13 referring to a rule, but what isn't currently in place 14 is acceptable.
15 This makes it sound like that plant to 16 plant to plant we can have a vastly different set of 17 exposure, either onsite/offsite exposure criteria, 18 than what -- than you would -- than I would envision.
19 It seems to me you can't have inconsistent 20 requirements or different requirements from plants --
21 from the standpoint of onsite and offsite dose 22 consequences to the public.
23 MR. RECKLEY: And I -- again, outside of 24 the introduction of the potential to set up emergency 25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.
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30 planning as another threshold, in order to reduce 1
offsite emergency planning you've got to lower the 2
radiological releases. Outside of that being 3
introduced, the criteria are basically the same as 4
light water reactors, which is 10 CFR 50.34, the 25 5
rem for the worst two hours, the 25 rem for --
6 MEMBER KIRCHNER: Population zone for the 7
entire event.
8 MR. RECKLEY: Right. So those two are 9
also in play here. You can back up and say basically 10 the analysis that was done for the existing fleet, in 11 terms of the leak rates and performance of the 12 containments, are basically the same. They were set 13 up, and the calculations showed that they remain below 14 those regulatory thresholds or guidelines.
15 Then, as severe accidents or beyond design 16 basis events were introduced increasingly into the 17 light water reactor licensing arena, the safety goals 18 ended up being used indirectly as acceptance criteria 19 because that's what we use as the backfit threshold.
20 And so requirements were put in place when 21 an action was needed -- and simplifying a little bit.
22 But since we use the safety goals as the threshold for 23 the backfit determinations, it became a kind of de 24 facto acceptance criteria for the light water fleet.
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31 So I don't -- it's a little different in 1
the way that you will address the releases will vary 2
a lot by technologies because what they're going to 3
rely on as the functional containment will look 4
different. But in terms of ultimately the acceptance 5
criteria, it will be basically the same, which is that 6
25 rem number, for design basis accidents and the 7
safety goal for very infrequent accidents.
8 MEMBER MARCH-LEUBA: The other problem I 9
have with that approach -- and let me just put it on 10 the record -- is that you will judge the acceptance 11 criteria for a set of events that you define. And 12 what we have found in severe accidents in the past is 13 there was an event that we didn't consider.
14 And, therefore, the releases that you are 15 going to calculate are -- by the way you calculated, 16 a lower bound, non-conservative bound of what the 17 release frequency is going to be, because you forgot 18 some events. And that's where defense-in-depth comes 19 along.
20 You put another barrier in there just in 21 case you didn't consider everything. And if you do a 22 probabilistic analysis of everything you have, and you 23 are right at the limit, you will say it's okay. I 24 will say it's not, because you didn't catch every 25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.
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32 possibility.
1 MR. RECKLEY: Right. I -- again, I think 2
when we come back and talk to you about the defense-3 in-depth approach in the summer, I hope you'll see 4
that -- that it's not as simple as what you just laid 5
out. And this is not the case, but if there were no 6
uncertainties, you could do what you were saying. You 7
could do that PRA, and you could say, "We know how 8
things behave, and, therefore, we'll -- we'll 9
establish things right to the -- to the acceptance 10 criteria."
11 The methodologies that we'll be presenting 12 to you in the summer recognize that that's not the 13 case, and there are a lot of uncertainties and you 14 have to take actions to -- to address those.
15 MEMBER MARCH-LEUBA: I'm eager to see --
16 I'm eager to see those. Can you move to the next 17 slide?
18 MR. RECKLEY: Uh-huh.
19 MEMBER MARCH-LEUBA: Okay. If -- I know 20 that we haven't defined this, but if we define the 21 blue line as our acceptance criteria, right now we 22 have the DOE and all the other reactors that have been 23 built for the last years, which are fantastic, super 24 safe, and incredible because the requirements from DOE 25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.
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33 were it has to be critical, so you can produce power, 1
and it has to be safe.
2 So they are orders of magnitude to the 3
left of that line. I mean, you cannot even -- But 4
the moment you put venture capital to design a real 5
reactor to be licensed, then the requirement change.
6 It has to be critical, so we can produce power, and it 7
has to be cheap. Safety doesn't count anymore because 8
safety is sustained below the blue line.
9 And I guarantee you when those reactors 10 designed by venture capitalists come, they will be 11 right at the limit. So by defining criteria, they are 12 going to get right there. And we are kind of in our 13 mind thinking about the DOE reactors, which are not 14 the ones that are going to come for licensing.
15 MR. RECKLEY: What we've seen --
16 MS. CUBBAGE: The dots will also have 17 uncertainty bands. This is Amy Cubbage from NRC 18 staff.
19 MEMBER REMPE: In fact, if I look at the 20 Y-axis, it has mean frequency. It doesn't have point 21 estimates. That implies you need to consider 22 uncertainties, right?
23 MR. RECKLEY: Well, if the --
24 MEMBER BLEY: Excuse. Amy, when you chime 25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.
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34 in, we need your name on the record.
1 MS. CUBBAGE: I did.
2 MEMBER BLEY: Oh, did you? I missed it.
3 Thank you.
4 MS. CUBBAGE: I did it fast.
5 MR. RECKLEY: The figures that we've seen 6
for the analysis that has been done would tend to show 7
that the doses tend to be very -- the consequences are 8
on the -- to the far left, close to the axis, and you 9
don't get that effect.
10 I understand what you're saying, and I 11 can't dispute it. I would simply say that, from the 12 regulatory perspective, the closer you get to the line 13 the more attention you get, the more safety systems 14 you're likely to have to add, and so there -- it's not 15 quite as simple as design to the line, because the 16 closer you are to the line the more expensive your 17 machine is going to be for that purpose.
18 Now, I understand what you're saying.
19 There's a tradeoff there, and that's really up to --
20 that's up to the designer to really say what kind of 21 strategy they -- they want to take, and there's always 22 tradeoffs in the design process.
23 MEMBER MARCH-LEUBA: My concern is on the 24 record.
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35 MEMBER BLEY: No, no.
1 MEMBER MARCH-LEUBA: And the moment you 2
draw the line.
3 MEMBER BLEY: I've got to throw one on the 4
record, too, because the claim that DOE reactors sit 5
way down here is -- is -- when we -- if it's my 6
reactor, I know it's way down low until I analyze it.
7 There have been a few DOE reactors that have been 8
analyzed impartially, and I suggest you are overly 9
optimistic.
10 MEMBER REMPE: And, in fact, some of them 11 don't operate at their full rate of power because of 12 that concern.
13 MEMBER BLEY: Yes, indeed. Or they don't 14 operate at all anymore.
15 MEMBER MARCH-LEUBA: I didn't want to 16 criticize the existing reactors. I'm thinking about 17 the future.
18 MEMBER BLEY: I know, but it's the context 19 there. It's overstated.
20 MR. RECKLEY: And you -- one can argue you 21 had this -- the same thing with the operating fleet.
22 And that is, as PRAs were introduced, and maybe not 23 only PRAs but other analytical improvements were made, 24 they were taken advantage of, right? You had power 25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.
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36 uprates, you had other -- you had other things to try 1
to take advantage of that -- of that identified 2
margin.
3 So I understand what you're saying. It's 4
not something I can really answer, other than it's up 5
to the designer.
6 CHAIRMAN CORRADINI: But I guess I want to 7
get to this, because you -- this is somewhere where 8
you had a -- you had a redline addition. I thought 9
you were going to mention something in the text. This 10 is the closest thing to a concept of how you would 11 establish this from a process standpoint.
12 But as I remember from the subcommittee 13 meeting, you were hesitant to say this is what you 14 want the Commission to consider. But this is getting 15 perilously close to a process.
16 MR. RECKLEY: No. I --
17 MEMBER BLEY: I want to chime in on that 18 one, too. It is, and it's similar to ones that were 19 used in a number of previous applications, not exactly 20 the same.
21 But the one thing I'll point out, and 22 we'll follow this later because I don't think it 23 applies right now, I mean, this is a concept, when you 24 actually try to apply it to a real reactor, you have 25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.
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37 to start thinking about how you do that without -- you 1
know, analysts can drop things smaller and smaller, 2
and you can get every scenario down low.
3 And what they had to do on 1860 when they 4
looked at an existing light water reactor was figure 5
out a way to group these, and they did it by looking 6
at systems and not looking at little contributors but 7
aggregating them at the systemic level, so that you 8
compare one plant with another. And in a sensible 9
way, you could apply such criteria, if this would 10 become a criteria.
11 CHAIRMAN CORRADINI: And I don't want to 12 get to your end, but I'm still trying to -- the way I 13 at least interpret the -- the policy paper is that --
14 don't go back a slide, but if I were to look at the 15 slide before, all containments essentially are 16 functional containments. Current containments are 17 functional containments because there is a defined 18 tech spec leak rate, which means it's a controlled 19 release of radiation. It is not a zero release.
20 MR. RECKLEY: Right.
21 CHAIRMAN CORRADINI: That's point one.
22 Point two is that what I think you're asking is just 23 permission to proceed, and we're not sure what you're 24 going to proceed with because we still don't have the 25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.
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38 concept you're going to proceed with, but we have a 1
sense of how you might attack it.
2 MR. RECKLEY: Right. That's generally 3
true. On this particular figure, I would say we're 4
making the Commission aware that we're going to more 5
officially formally adopt this kind of approach. What 6
the foot -- what the footnote on the slide and the 7
text in the SECY is saying is we're going to use this 8
approach, this methodology, or we're proposing to.
9 What we're not ready to ask the Commission 10 to weigh in on is where the lines are. Ten to the 11 minus four, okay, that -- that's a line on that graph.
12 It may stay there over the summer as we work with 13 licensing modernization on the -- on this next 14 approach. Maybe it changes. I'm not predicting. It 15 has been -- since NGNP and a lot of other projects, 16 these lines have been fairly steady and unchanging.
17 But we weren't being asked yet at that time to 18 officially endorse them in regulatory guidance.
19 The document we'll be preparing over the 20 summer will include a graph like this that we will 21 endorse or propose to endorse in regulatory guidance, 22 and we just wanted the summer to work out whether we 23 want to tweak any of these lines. So that's -- that's 24 the disclaimer we were putting into the paper.
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39 The concept we're ready for. The 1
specifics give us to the next reg guide, which we plan 2
to develop over the summer.
3 MEMBER BLEY: When you get to that reg 4
guide, I'd recommend you look back at 1860's 5
application.
6 MR. RECKLEY: Yes.
7 MEMBER BLEY: Because how in this reg 8
guide you tell people to use this is not transparent 9
without a fair amount of work.
10 CHAIRMAN CORRADINI: And that was the time 11 where there was debate amongst the committee that 12 caused it to kind of stop in the midst of preparation.
13 I mean, because I -- I seem to remember, as we went 14 back to 1860, the question was really, what are the --
15 as you said, where do you draw the lines? What's the 16 access supposed to be? How do you bundle these so you 17 don't, by fractionation, make them look --
18 MEMBER BLEY: What I can say is, at some 19 point -- because I was involved in that process. At 20 some point in that, it looked like there was going to 21 be a volunteer of a new design to actually apply --
22 try to apply those approaches and that disappeared.
23 And then there was the suggestion, why don't you apply 24 it to an existing LWR, and in fact, yeah, that 25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.
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40 probably took another six months or longer before that 1
got worked in.
2 MS. CUBBAGE: So this is Amy Cubbage 3
again. Just to refresh that we're coming in June to 4
the subcommittee for the preview of these topics, and 5
so we'll be able to get into a lot more specifics of 6
where the staff is headed on that, and then again in 7
October the subcommittee, and then December full 8
committee on that other draft reg guide.
9 MEMBER BLEY:
So June is the 10 modernization?
11 MS. CUBBAGE: That's what we're talking 12 about.
13 MEMBER BLEY: And that's where you're 14 talking about. These will all start coming together 15 there.
16 MS. CUBBAGE: Absolutely.
17 MR. RECKLEY: The other note is, again, 18 this isn't the first proposal to use this, hopefully.
19 In that that's the reason for the subcommittee visits, 20 we have -- we have addressed some of those concerns or 21 the -- the industry has in their guidance that we hope 22 to endorse.
23 But our message in the previous white 24 papers is, you know, stop calling it a limit line, for 25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.
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41 example. It's not an acceptable line. It's a 1
judgment call, and what we're planning to use it for, 2
the further away you are, the more comfortable we are.
3 Not if you're on one side you're okay and if you're on 4
the other side you're not.
5 In terms of other measures -- and then 6
I'll move on -- it's not just this line. You do have 7
to consider aggregating all of the events, so that you 8
don't end up doing some maneuvers to say I don't have 9
any event that's -- that's over -- that's of concern.
10 You also look at aggregate measures to say 11 that all of the -- all of the events put together, but 12 that's a preview, a trailer for the -- for the June 13 meeting that -- that we'll be in for.
14 MEMBER KIRCHNER: For the record, too, 15 10 CFR 50.34 makes it clear that it's not that point.
16 That's an --
17 MR. RECKLEY: It's not a point.
18 MEMBER KIRCHNER: It's not a point. That 19 the expectation is below.
20 MR. RECKLEY: Yes.
21 MEMBER KIRCHNER: And I think the 22 Commission's prior statements on advanced reactor 23 expectations would drive you in the same --
24 MR. RECKLEY: Push it even further away.
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42 MEMBER KIRCHNER: Yes.
1 MR. RECKLEY: Right.
2 MEMBER DIMITRIJEVIC: Well, this is what 3
I was going to suggest. It would be very interesting 4
because I have a tough time imagining where the 5
current light water reactor -- because I'm not sure of 6
the meaning of some of those regions.
7 So it looked to me the current light water 8
reactor would be farther on the left based on this 9
curve, and we want to design for better performance 10 than that. So it would be interesting actually to 11 look where the current light water reactor fit on this 12 curve. You know, why I have a problem, because 13 anticipated operational occurrence are initiating 14 events, not sequences.
15 So I am not sure, does this mean every 16 sequence would start to an anticipated initiating 17 event or what does it mean in the -- in the PRA world 18 of the life of the reactor? So for me it will be 19 interesting to see how these compare -- how this 20 current fleet fits on this curve.
21 MS. CUBBAGE: So one way -- this is Amy 22 Cubbage again. One way I -- just thinking about it as 23 you were talking -- good points is that, yes, the 24 current LWR, we would expect all to be inside of those 25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.
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43 lines because those are bounded in regulatory 1
requirements like 50.34.
2 However, they may need a lot more safety 3
systems and components to get there, whereas these new 4
plants may have more inherent safety characteristics, 5
passive, et cetera, such that in a more simpler way 6
they can achieve the safety. I mean, that's just one 7
way to think about it.
8 MEMBER DIMITRIJEVIC: Well, but in the 9
end, we still talk about frequency. So it doesn't 10 matter how did you get there, but --
11 MS. CUBBAGE: Oh, yeah. That -- yeah, I 12 wasn't speaking to that part of it, but --
13 MEMBER DIMITRIJEVIC: Yeah.
14 MS. CUBBAGE: And, you know, just to get 15
-- drill down a little on the advanced reactor policy 16 statement, there is not an explicit expectation that 17 they be quote/unquote "safer," but they are supposed 18 to use simplified inherent passive means to achieve 19 safety with less reliance on power, operator actions, 20 et cetera, et cetera.
21 So the Commission policy really has the 22 expectation of a different way of achieving safety.
23 MEMBER BLEY: Amy, I think when you made 24 your statement about existing reactors you meant the 25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.
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44 design basis events for existing reactors.
1 MS. CUBBAGE: Yes. Yes.
2 MEMBER BLEY: Not all possible events 3
beyond the design basis.
4 MS. CUBBAGE: That's a good point. Yes, 5
I was focusing more on --
6 MEMBER BLEY: Which would be looked at on 7
here, by the way.
8 MS. CUBBAGE: Yes. I was focusing more so 9
on the -- the AOO DBA portion, that we would expect 10 them to be below the line. You're right.
11 MR. RECKLEY: And this -- this approach is 12
-- again, the light water approach evolved. And so 13 one difference here is that there will be a much more 14 structured look at those beyond design basis events, 15 those events of lower frequency, than may have been 16 done for the light water, not -- not in terms of the 17 PRAs. The PRAs have probably caught up to look at 18 those events. But in terms of the regulatory 19 treatment of them, this is being built into this 20 approach.
21 CHAIRMAN CORRADINI: So let me ask a --
22 maybe -- I know we asked you this question at the 23 subcommittee, but maybe -- I guess I want to ask it 24 again because I don't remember the answer, to be quite 25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.
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45 honest. All of these are design basis events which 1
essentially would be looking at some sort of 2
calculational approaches to what the mean is, what's 3
the uncertainty in both directions.
4 But then if I go to Chapter 15, I have a 5
set of required assumptions that make me bias --
6 forget about the Y-axis, makes me bias the X-axis in 7
a -- in a direction. So is that still part of the 8
anticipation is they will have to be --
9 MR. RECKLEY: Yeah.
10 CHAIRMAN CORRADINI: Okay.
11 MR. RECKLEY: Really, just --
12 CHAIRMAN CORRADINI: So I have -- so if I 13 might say, you don't have to go back to the cartoon, 14 but as you pepper this with what you have as a bundle 15 of potential events, you would bias them towards the 16 line based on the DBA assumptions.
17 MEMBER REMPE: Well, I thought maybe in 18 our subcommittee meeting, but somewhere I've seen that 19 it wouldn't quite be the same. One might say I'll 20 only rely on safety-related equipment, structures, and 21 components, instead of -- and call those to be design 22 basis events. It's not the traditional way of doing 23 things is what I thought I heard.
24 MR. RECKLEY: Well, the summary of this 25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.
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46 curve, if you just put it in the bullets, is the 1
events are looked at from a probabilistic standpoint, 2
a PRA standpoint, and broken down by frequency into 3
anticipated operational occurrences, design basis 4
events, and beyond design basis events based on the 5
event frequencies.
6 MEMBER DIMITRIJEVIC: Well, okay. This is 7
what is very important for me. It is based on event 8
sequence frequencies, not on event -- not on 9
initiating event frequency.
10 MR. RECKLEY: Under this proposal, yes.
11 MEMBER DIMITRIJEVIC: Yes. So that's 12 completely different because there is million event 13 sequences that start with a different initiator.
14 MR. RECKLEY: Yes.
15 MEMBER DIMITRIJEVIC: Right.
16 MR. RECKLEY: Right.
17 MEMBER DIMITRIJEVIC: So, for example, 18 when we talk about design -- beyond design basis 19 events, let's say tsunami of 14 feet, that would not 20 only influence so much my release and steam generator 21 tube rupture, which is design basis event. So this is 22 what I just want to say. This is very difficult to 23 say what we are taking about, because from the PRA 24 point of view we have like, for example, large release 25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.
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47 frequency, which all the initiating events contribute, 1
but which ones contribute the most we don't know.
2 It doesn't have to be beyond design basis 3
event. Not beyond -- it's not necessarily beyond 4
design basis events which contribute most to large 5
releases. And this is which we are talking about here 6
is releases.
7 MR. RECKLEY: If the -- if the events 8
result in releases, you -- yeah, they -- they --
9 MEMBER DIMITRIJEVIC: See, for example, 10 the loss of offsite power, which is like, you know, 11 one of the high frequency events often leads to the 12 largest releases. So how -- so what we are talking, 13 where does that fit on this curve? I mean, you know, 14 or that's what I am asking. I mean --
15 MR. RECKLEY: Well, the --
16 MEMBER BLEY: Can I help you out, Bill?
17 MR. RECKLEY: Please.
18 MEMBER BLEY: And especially with respect 19 to what Joy said earlier, if you look back at the MHGT 20
-- MHGTR application and the way they approached it, 21 if you look at 1860 and what they did, and if you look 22 at the white papers and what they were proposing, all 23 of those looked at whole PRA sequences, plotted those, 24 and then looked at ways to aggregate them to make sure 25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.
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48 you were looking at the same thing. And that was the 1
aggregations that dealt with these things.
2 But they all came up with this concept, 3
and Dana argued against it at the subcommittee 4
meeting, by the way. We ought to have something 5
analogous to the current design basis accident, so 6
you'll take those out of that PRA set, and for that 7
small set, which sit over by the axis because they 8
have no releases or no big releases, you'll apply the 9
old rules of Chapter 15 to them and that adds a 10 conservatism.
11 Dana was saying, well, why in the world 12 should we do that? Should we still be going back to 13 that? And that's something I think we'll talk about 14 this summer.
15 MR. RECKLEY: Right.
16 MEMBER BLEY: That's a kind of definition.
17 But that's where the thing you talked about was those 18 they called licensing basis events, and they treated 19 them the way we treat design basis accidents now and 20 added a lot of conservatism into them and designed the 21 systems so that they could still meet those kind of 22 conservative criteria.
23 MEMBER REMPE: But, again, we can't apply 24 all of the Chapter 15 things to a non-LWR. So, in 25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.
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49 some cases, perhaps the gas reactor --
1 MEMBER BLEY: The Chapter 15 kinds of 2
assumptions.
3 MEMBER REMPE: Yeah, kinds. But I thought 4
that they were trying -- some of the designers are 5
trying to push back and say, okay, let's just say 6
we're going to rely on safety-related equipment that's 7
cost -- safety grade, and that's it, and that's where 8
I thought they --
9 MR. RECKLEY: And that's the last bullet.
10 So -- so the first sweep will be just looking at 11 events and analyzing them kind of in normal PRA, what 12 equipment do I have, how is it going to work, what 13 equipment fails, that might put me on a different 14 sequence, but you just do all of those assessments, 15 and that's the first -- the anticipated operational 16 occurrences, design basis events, beyond design basis 17 events.
18 And the reason for largely coming up with 19 those designations is the acceptance criteria could be 20 different for those. For anticipated operational 21 occurrences, there better be no releases basically or 22 very small releases, and you shouldn't be failing even 23 your first fission product barrier, right? I mean, 24 that's the same concept as now. Anticipated 25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.
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50 operational occurrences should -- should be benign.
1 Then you get into design basis events less 2
frequent. Well, they are less frequent. You can have 3
-- in theory, rely on different systems, go a little 4
further in your defense-in-depth, you are now relying 5
on a backup system perhaps, and your offsite dose 6
could be a little higher.
7 And then if you get into the very 8
infrequent, again, you're starting to pick up doses 9
that could be more significant, but you're comparing 10 them to the -- to the safety goal as your -- as your 11 criteria.
12 Now, all of that is done, and then in 13 addition to that assessment you do another set of 14 events that you're picking out of that design basis 15 event category. So you're not going way down into the 16
-- into the very unprobable events, but you're picking 17 out of the design basis event category the events and 18 saying, "For those I am going to now analyze them in 19 a more traditional Chapter 15 sense."
20 And I'm only going to rely on design -- on 21 safety-related equipment. The assumptions might be a 22 little more conservative in terms of your initial 23 conditions, and the computer codes that you're using 24 might be more in line with Chapter 15. So you'd pick 25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.
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51 up all of that Chapter 15 conservatism.
1 And you're doing that for a number of 2
reasons. Those are a little easier and more clear-cut 3
historically to define engineering safety margins 4
because you're now calculating temperatures, 5
pressures, things you can compare, the ASME code 6
requirements.
7 And that's also traditionally where you 8
get your technical specifications from, so you can 9
maintain that kind of historical connection between 10 Chapter 15 and where you're getting other regulatory 11 controls on your safety-related equipment.
12 So this really was kind of a compromise, 13 bringing a large part of the regulatory structure for 14 light waters or existing plants into this, trying to 15 improve it, trying to make it more structured, more 16 organized, but also keeping some continuity in terms 17 of things like Chapter 15, technical specifications, 18 and safety classification.
19 MEMBER BLEY: I just wanted to interrupt 20 with two things. One is we're down to our last 55 21 minutes.
22 MR. RECKLEY: Right.
23 MEMBER BLEY: And we have more things to 24 talk about on functional containment.
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52 MR. RECKLEY: Right.
1 MEMBER BLEY: This I think is stuff we're 2
going to address in the summer more. But if somebody 3
wants to pursue it a little bit, I think we're okay.
4 But we don't want to run out of time for the new 5
things here.
6 MEMBER DIMITRIJEVIC: But this is in that 7
paper.
8 MEMBER RICCARDELLA: I have a question.
9 I'm just trying to understand that chart. Could you 10 go back to the chart? So if I evaluated an existing 11 operating light water reactor, and wanted to plot it 12 up here, would I get a whole bunch of points for each 13 event?
14 Or would I get a line that's the -- that, 15 you know, presumably all the points, all the 16 individual points for each event sequence would be 17 below that line. But do I have to do some summing to 18 get a line -- a bounding line for all of the events of 19 that frequency and make sure that the -- I mean, that 20 last one --
21 MR. RECKLEY: That's a valid point.
22 MEMBER RICCARDELLA: Is it a cumulative 23 plot or a distributed plot?
24 MR. RECKLEY: It's a bunch of points.
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53 MEMBER RICCARDELLA: Huh?
1 MR. RECKLEY: A bunch of points for events 2
-- typically not individual because you're grouping 3
them, but -- but families or small groups of sequences 4
that are very similar.
5 MEMBER RICCARDELLA: But if I had a whole 6
bunch of points that all had a frequency of 10 to the 7
minus third, and if I had a thousand of them, then 8
I've got a -- then I've got a much higher frequency, 9
right?
10 MEMBER STETKAR: That's what Dennis was 11 talking about earlier. This notion -- until we have 12 the opportunity to see what they work through sometime 13 in the summer about what is an event sequence, we 14 don't -- it's difficult to implement this process 15 because an event --
16 MEMBER BLEY: Two things --
17 MEMBER STETKAR: -- some people will say 18 an event sequence is a cut set, and billions and 19 billions and billions of cut sets are billions and 20 billions and billions of sequences, and you run into 21 your problem.
22 MEMBER BLEY: Go back.
23 MEMBER STETKAR: Other people will say 24 it's a path through a stylized event tree, but people 25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.
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54 draw event trees differently. So that's not a 1
sequence either. So until the staff and the industry 2
have some coherent understanding of what you mean by 3
a sequence, you can't answer your question about --
4 MEMBER BLEY: But to help a little bit, 5
two things. If you looked at the design basis events 6
for current light water reactors, they are all 7
clustered along the Y-axis. They're all there. They 8
aren't anywhere else.
They're at different 9
frequencies, but they're over there at almost no 10 release. And if you want to see one way you could go 11 12 MEMBER DIMITRIJEVIC: Wait, wait, wait, 13 wait, wait.
14 MEMBER BLEY: If you want to see one way 15 you could go at this, I'd recommend you look at 16 Appendix E in 1860, NUREG-1860. And there are a 17 couple of other sources to look at, but that's the 18 easiest one to find. I'm sorry, Vesna.
19 MEMBER DIMITRIJEVIC: Okay. Because it's 20 still important for me to understand what you just 21 said, because design basis events with vessel failure, 22 mitigating system --
23 MEMBER BLEY: No longer design basis 24 event.
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55 MEMBER DIMITRIJEVIC: Oh, what do you mean 1
it's no longer --
2 MEMBER BLEY: I mean the things that are 3
analyzed in Chapter 15.
4 MEMBER DIMITRIJEVIC: Okay. Then there is 5
no single event, other than maybe vessel failure, 6
which will actually result in releases.
7 MEMBER BLEY: Which is not analyzed in 8
Chapter 15. That is definitely not a design basis 9
event.
10 MEMBER DIMITRIJEVIC: Okay. So any 11 additional failure makes an event?
12 MEMBER BLEY: Not a design basis event.
13 MEMBER DIMITRIJEVIC: Here, how it's 14 interpreted, right?
15 MEMBER BLEY: Yeah. All of the -- all of 16 the sequences in the PRA have to go here somehow, but 17 you have to decide how you -- how you ought to arrange 18 them to look at them here. But the design basis --
19 MEMBER DIMITRIJEVIC: All right. Well, 20 that's completely strange for me. I mean --
21 MR. RECKLEY: But it's -- this is a little 22 different than the -- than the light water approach 23 because in light water -- in light water or existing 24
-- this was all done after the fact. So this is --
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56 this is trying to bring this concept into the 1
regulatory framework and a little more organized.
2 So it will be -- it will be a little 3
different. And, again, I -- in the summer we'll --
4 we're making notes that this will be an area that we 5
have to explain a little better. And it was an issue 6
when we were doing NGNP reviews, this -- this --
7 what's a family, what's a sequence. It was the same 8
discussions.
9 MEMBER BLEY: I can give you three 10 references that I mentioned, the old gas reactor 11 submittal, the 1860, and the white papers. We wrote 12 letters on those three or four years ago, yeah. So we 13 have all of that we can look at.
14 MR. RECKLEY: So getting beyond the -- the 15 events, the paper --
16 MEMBER DIMITRIJEVIC: Wait. Because I 17 just thought about, if this isn't called event 18 sequence, so then what is event sequence, for example, 19 for unprecedented operational occurrence? What's --
20 or what is event sequence for, let's say, loss of 21 offsite power? Because that is --
22 MEMBER BLEY: There are lots of them. You 23 know that --
24 MEMBER DIMITRIJEVIC: Hmm?
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57 MEMBER BLEY: There are lots of them.
1 They all start with a loss of offsite power.
2 MEMBER DIMITRIJEVIC: Yes. But then you 3
say if it's only additional -- if there is any 4
additional failure, it is not anymore, that design 5
basis event.
6 MR. RECKLEY: That would all depend on the 7
plant and the -- and the reliability or whatever you 8
have in place to -- to respond to it. So --
9 MEMBER DIMITRIJEVIC:
But we just 10 discussed the case, if I have event sequence, we have 11 additional failure, loss of offsite power. These are 12 failures to start for whatever, failure of recovery, 13 blah, blah, blah, blah. That's not any more the 14 event, design basis event. That's what that has just 15 told me.
16 MEMBER BLEY: You've read Chapter 15. A 17 large LOCA is analyzed as a large LOCA with -- in most 18 reactors one loop not working, and one other active 19 failure.
20 MEMBER DIMITRIJEVIC: So that's event 21 sequence they are talking here about.
22 MEMBER BLEY: No.
23 MEMBER DIMITRIJEVIC: It's not the PRA 24 sequence.
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58 MEMBER BLEY: That is -- so that's makes 1
a bunch -- a whole bunch of things I don't think I can 2
answer at one time.
3 MR. RECKLEY: I think some of the --
4 MS. CUBBAGE: What I was going to say is 5
this will be based on the PRA sequences, not a 6
stylized deterministic approach to all of the 7
different Chapter 15 things.
8 MEMBER BLEY: Selection of the events, 9
yeah.
10 MS. CUBBAGE: Right.
11 MEMBER BLEY: It was --
12 MS. CUBBAGE: It was just certain events 13 that were selected to be representative for the large 14 light --
15 MEMBER BLEY: "Selected" is the right 16 word. They were picked with some rationality.
17 MR. RECKLEY: We'll provide what Dennis 18 was mentioning. We'll provide that background 19 information, the 1860 and some of the NGNP papers that 20
-- that describe how -- how this works a little 21 better.
22 And, again, we'll be back in the summer, 23 first -- first meeting in mid-June.
24 The other important item, or another 25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.
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59 important item within the paper that we talk about 1
because we have to mention it is -- is mechanistic 2
source term, because obviously the purpose of the 3
functional containment is to retain the radionuclides 4
within the plant.
5 And the importance then of understanding 6
the behavior of the reactor systems, the transport of 7
the radionuclides for various events, is key, and 8
that's -- there has been previous white papers talking 9
about mechanistic source term.
10 This figure also, though, I like this 11 figure that -- that originated in the NGNP papers and 12 then goes forward is some of the topics we have been 13 talking about, we're laying out the highest level 14 regulatory kind of framework here. This -- this 15 figure starts to show some of not only the high-level 16 regulatory questions, but the technical work that has 17 to get done. And we often get questions of how you 18 can set out a regulatory approach before you've done 19 some of the technical work.
20 And, you know, we'll be the first to admit 21 that's a challenge. We're trying to lay out 22 performance-based approaches such that we'll 23 acknowledge all of these things need to be done, and 24 in many cases they're only beginning for some designs 25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.
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60 and technologies. But they will need to be -- to be 1
done ultimately.
2 But, again, what we're being asked is 3
before there is a -- before there is a large 4
expenditure of money on something like fuel 5
qualification, to understand how fuel qualification 6
fits into the whole plant design. And we'll talk a 7
little later about I think it's obvious how those kind 8
of things go together.
9 How much do I have to prove the fuel is 10 going to retain the material, can be in a design 11 aspect a function of what am I going to require in 12 terms of additional barriers. And so, but what's key 13 to this figure is even when we lay this out in a high-14 level regulatory context, we're -- you know, the 15 designers work -- this is just freeing them up to know 16 what they need to do, but they still will need to do 17 fuel qualification work.
18 Dana had brought up last time the 19 analytical codes and the validation work. That -- you 20 know, we're assuming -- we don't talk about it very 21 much in this paper. It's inherent in this, and if we 22 need to clarify -- we tried, but we can just make it 23 clear all of this work has to be done.
24 We're just laying out a framework, and all 25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.
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61 of the underlying technical work and understanding of 1
the designs still needs to be -- to be done. We're 2
just -- you know, we're -- when this paper goes up, it 3
will be still the beginning process. This doesn't 4
really enable anybody to just quickly move through.
5 It only enables them to know what they 6
have to do in terms of all of this work, in terms of 7
developing the equipment, the qualification of the 8
materials, the qualification of the fuel, the 9
qualification of the computer codes, and all of that.
10 So --
11 MEMBER KIRCHNER: Bill, I would just throw 12 out a caution that both the NGNP work and the -- their 13 approach to functional containment was predicated on 14 having robust solid fuel, not circulating fuel. I 15 just --
16 MR. RECKLEY: And we're -- we're in the --
17 MEMBER KIRCHNER: So just --
18 MR. RECKLEY: No, no. And we're now in 19 the midst of -- if you're alluding to molten salts, 20 we're -- we're just in the process now of starting to 21 say what does fuel qualification mean for a fuel 22 that's -- that's going around the reactor coolant 23 system. So we --
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62 first barrier.
1 MR. RECKLEY: And that's -- that's a 2
proposal. I mean, that's a first step. So -- so we 3
had -- we had the event categories.
4 And, again, the structure that is being 5
proposed in the paper, the reason we spent so much 6
time on event categories is because it really does 7
explain how we are proposing -- the methodology that 8
is being proposed for defining performance criteria, 9
because you have, just like you have now, different 10 performance criteria for -- or acceptance criteria.
11 Maybe I'll change the language. You have different 12 acceptance criteria for each event category, and you 13 have that now largely with the operating fleet. That 14 will continue.
15 In general, the more you go down in terms 16 of lower and lower frequencies, the more the -- the 17 higher the acceptance criteria is in terms of 18 allowable consequences, if you will.
19 MEMBER DIMITRIJEVIC: Well, what type of 20 acceptance criteria?
21 MR. RECKLEY: And we'll go in the next 22 slide --
23 MEMBER DIMITRIJEVIC:
No, no, no.
24 Currently, you compare it to current. So what type of 25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.
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63 acceptance criteria you are saying goes down with it?
1 MR. RECKLEY: Well, if you start with 2
anticipated operational occurrences, in light water or 3
current reactors, those are basically required to show 4
that you don't fail the cladding on the fuel. Then, 5
by the time you get to large break LOCAs, you are 6
using the 2200. And this is in the Chapter 15 space.
7 In --
8 MEMBER DIMITRIJEVIC: In the PRA space.
9 MR. RECKLEY: In the PRA space -- I'm not 10 a PRA person, but in general you're going to aggregate 11 those and compare them to the safety goals.
12 MEMBER DIMITRIJEVIC: Yes. But that's 13 completely independent of this, and it doesn't change 14 once you --
15 MR. RECKLEY: And that is one of the --
16 that -- to some degree it's one of the differences 17 that will exist, in that large light water reactors --
18 man, I wish Marty or somebody was here to be my call 19 a friend, but he has left. And I'm going to go beyond 20 my station here.
21 But, and maybe I'll look at the PRA people 22 here, but anticipated operational occurrences aren't 23 going to get much attention in a light water reactor 24 PRA, because you're ending it very early, saying I 25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.
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64 don't get core melt, I don't get core damage.
1 And so those event sequences are going to 2
end relatively -- I mean, they're not addressed very 3
much. In this sequence -- in this proposal --
4 MEMBER BLEY: They're in there, but 5
they're not tracked.
6 MR. RECKLEY: Yeah, okay.
7 MEMBER DIMITRIJEVIC: Wait a second. Do 8
you consider transient anticipated occurrence, plant 9
transient? Yeah. I mean, therefore, we have to be 10 mostly protected for --
11 MEMBER BLEY: There's a group of 12 transients that are called anticipated events, but 13 there are also some transients that are in the PRA 14 that go well beyond those.
15 MEMBER DIMITRIJEVIC: Okay. Well, that's 16
-- I just want to say that PRA has nothing to do, and 17 actually you need to protect more against more likely 18 events to, you know, prevent them to resulting --
19 MR. RECKLEY: And that's what this would 20 show is that your first line of defense is going to 21 work most often --
22 MEMBER BLEY: I've got to interrupt.
23 MR. RECKLEY: Yeah.
24 MEMBER BLEY: We're running out of time.
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65 MR. RECKLEY: Yeah.
1 MEMBER BLEY: And we've been on this topic 2
longer than we have time for.
3 MR. RECKLEY: Okay.
4 MEMBER BLEY: You've got to get us to 5
anything that has changed.
6 MR. RECKLEY: Okay. So to go to the -- to 7
the meat of the paper, then, that the proposed 8
methodology is to take the acceptance criteria for 9
each event category -- for example, the fuel design 10 limits or the frequency consequence targets, which are 11 different for each event category, and you see in the 12 terms of the functional containment, which is those 13 things that you're putting in place to retain 14 radionuclides, what structures,
- systems, and 15 components am I relying on to meet the acceptance 16 criteria for that event category.
17 And so, for
- example, under normal 18 operations, I'm operating under Part 20 as my 19 acceptance criteria. Well, what, under normal 20 operation, am I relying on to keep me under Part 20?
21 And anticipated operational occurrences assume I set 22 my acceptance criteria to be some fuel design limit 23 like the specified acceptable radiological release, 24 the SARRDL, or -- or on the molten salts maybe it's 25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.
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66 the integrity of the first barrier. Then that becomes 1
my acceptance criteria for the event category. What 2
am I
relying on in order to retain those 3
radionuclides?
4 And so that -- that just becomes the 5
methodology for defining what is the requirements for 6
functional containment. You aggregate, then, all the 7
structures and systems and components that I'm relying 8
on for all of the event categories, and then that 9
becomes my performance criteria for the functional 10 containment.
11 There is a separate discussion in the 12 paper on physical enclosures or physical buildings, 13 only because the history of this topic has always --
14 as soon as you say containment, what comes into 15 people's minds is the structure. And so there's 16 always -- often been discussions of what is the -- the 17 purpose or the role of the physical enclosure, so we 18 included a discussion within the paper.
19 Certainly, if there is a -- if there is a 20 role for the building or the enclosure in retaining 21 radionuclides for any event category, now that 22 building is part of my functional containment. In 23 some cases, it might be part of my functional 24 containment for maybe only the last category.
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67 So using that as an example, if I'm only 1
using my reactor building as a last line of defense 2
against a beyond design basis event, it's still now 3
part of my functional containment. But how I define 4
what the regulatory requirements are will be 5
reflective of what are regulatory requirements for 6
equipment serving beyond design basis events.
7 So it could end up being a reactor 8
building that's non-safety-related, but credited 9
within my mechanistic source term in a best estimate 10 approach to how that building would help me retain the 11 radionuclides. Whereas, I could also be crediting a 12 reactor building or enclosure for my design basis 13 accidents in order to retain the fission products, in 14 which case now that enclosure will be a safety-related 15 structure under the existing arrangement.
16 So it's just a way to organize and 17 determine what is serving the role of retaining the 18 radionuclides and then setting the regulatory 19 requirements in line with which event category it's 20 being credited for.
21 That's not dramatically different than how 22 stuff is done for light water reactors where you just 23
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68 same thing to say, okay, is it serving any safety-1 related function? And then it's on the -- you know, 2
it's on the cue list. If it's -- if it's not, it 3
still may have requirements to meet some regulation or 4
it may have a reliability goal within the PRA or the 5
maintenance program.
6 So it's not dramatically different. We're 7
just trying to be a little more structured and 8
organized. Then, the other thing that is called out 9
in the paper, again, just because it's so common, if 10 you go into discussions of the physical enclosure --
11 MEMBER REMPE: Bill, before you leave that 12 slide, when I looked back about our meeting last time, 13 the only thing I didn't you that I wanted to was I 14 looked at the June 2003 paper and how the 15 Commissioners had not approved the recommendations 16 related to the confinement building.
17 They cited you needed to have performance 18 requirements and you should work with industry, and 19 some things that they wanted to get back from you 20 before they ever considered it. Do you have any feel 21 about whether you think you've got enough now that 22 they can make a decision? Because, frankly, I think 23 their not making a decision has hindered progress in 24 this area. And what do you think?
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69 MR. RECKLEY: Well, what we're going to --
1 what we're going to say in the paper, and then there's 2
a Commission meeting coming up, and we'll tell them 3
this paper is coming, but in general the message that 4
we're getting is there are too many questions about 5
what is fixed and what's in play, what can a designer 6
have under their control, and -- and that is the 7
purpose of the paper.
8 So, yeah, I won't say that -- yeah. But 9
a decision is needed now, so that we can incorporate 10 functional containments into the next set of papers to 11 say what the overall framework is going to be.
12 So, yeah, we're going to say a decision is 13 needed as soon as the -- obviously, we don't dictate, 14 but --
15 MEMBER REMPE: And you hope that you've 16 got this --
17 MR. RECKLEY: We hope.
18 MEMBER REMPE: -- industry interactions 19 indicate you probably -- they think you have enough 20 stuff in there for them to --
21 MR. RECKLEY: Right. I mean, this -- this 22 reflects -- and, really, it has been fairly continuous 23 fits and starts. I shouldn't say continuous. It is 24 over a long period of time with fits and starts, but 25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.
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70 this same basic approach is -- is not -- it's from the 1
'80s all the way up to now. Even the paper in '93 2
said this approach would be built around event 3
categories. This is -- again, it's not -- this whole 4
-- this whole approach.
5 And then the most interaction lately that 6
we would rely on in terms of this notion of the deal 7
with stakeholders was NGNP, and then the follow-up 8
more recently with this licensing modernization 9
project. So, yes, we think we've done it.
10 MEMBER REMPE: We've matched the rear --
11 it's different commissioners, but you know --
12 MR. RECKLEY: Yes. We think -- we think 13 we have, and we think -- and the underlying message is 14 we need a decision on this in order to -- to move 15 forward.
16 I already really talked about this in the 17 previous, but -- but it just reinforces, for example, 18 that there are related topics, and some of this will 19 have to get worked out in an integrated fashion 20 because you have all of these parts. And as soon as 21 you try to answer one part in isolation, then it just 22 cascades back.
23 And so one that was brought out in Reg 24 Guide 1.232 was the use of specified acceptable 25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.
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71 radionuclide release design limits, or SARRDLs, and 1
the role that -- the relationship between a SARRDL and 2
the functional containment.
3 And so the -- you know, the designers are 4
looking at an approach where they could set very 5
restrictive SARRDLs, meaning there wouldn't be very 6
many radionuclides in the inventory to be released, 7
and then you can have a functional containment that 8
works a certain way.
9 If you're going to -- if you're going to 10 say all plants need to have basically the equivalent 11 of a -- of a current pressure-retaining containment, 12 it raises other issues, but it also would say, if I 13 have another barrier, maybe my SARRDLs can be higher.
14 And so those tradeoffs are what the 15 designers are looking for, and we're just -- we're 16 just trying to basically, again, say as long as the 17 integrated plant design considers all of these things 18 and models them through, they have the flexibility to 19 pick where they want to put the emphasis, provided the 20 net result, which is public health and safety, is --
21 is provided or protected.
22 MEMBER KIRCHNER: Just Bill, one more 23 cautionary note. On certain design concepts where you 24 do have liquid fuel, you, in the traditional sense, 25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.
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72 have already eliminated one of the barriers. And I 1
would suggest, I think your paper, although I didn't 2
see it in the viewgraphs, talks about undue reliance 3
on any one barrier.
4 MR. RECKLEY: That was --
5 MEMBER KIRCHNER: Because now the burden 6
of proof, I would presume, would be much higher on how 7
essentially leak-tight that barrier is for that kind 8
of concept.
9 MR. RECKLEY: Right. And, again, you have 10 to evaluate the fuel form, and assume it -- assuming 11 it reaches your first barrier, what happens to the 12 fuel? And, therefore, then what kind of barrier do I 13 need given that it reached the first, right?
14 So, again, all of the molten salt 15 discussions are preliminary. But there is -- there is 16 some discussion about the ability of the salt, once it 17 reaches the first barrier, to actually retain the 18 fission products and, therefore, the role of the 19 second barrier might not be as great as it sounds on 20 first blush. Not that you don't need a second 21 barrier, but what -- what it has to address in terms 22 of the potential to retain nuclides --
23 MEMBER KIRCHNER: It's not just fission 24 products. You have the actinides in circulation.
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73 MR. RECKLEY: Oh, yeah, yeah. Okay.
1 So -- so, again, this is just summarizing 2
basically the proposed approach, and I've gone through 3
it before. The physical structures, the paper lays 4
out some other possible uses, the protection against 5
external events, weather, aircraft impact, potential 6
delay in security scenarios, and so forth.
7 So in addition to whatever role it has in 8
retaining radionuclides, the physical enclosure might 9
be subject to any number of other regulatory 10 requirements or asset protection requirements that the 11 designer is -- is establishing.
12 And so to get to Dr. Bley's suggestion, we 13 do want to point out what we changed in the -- in the 14 paper, and it's not a lot, but -- but we did try to 15 address some of the things that we heard. One is in 16 a few places -- and I don't want to overstate, but in 17 a few places we -- we made sure that it was 18 characterized as a methodology.
19 These are not performance criteria if 20 you're looking for physical parameters. This is a 21 methodology by which a designer can determine those 22 physical parameters based on all the discussion we 23 just had about what are they relying on for functional 24 containment. So --
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74 MEMBER BLEY: By the way, you've still got 1
approach in some places in the paper.
2 MR. RECKLEY: Yes.
3 MEMBER BLEY: The same thing that you used 4
methodology for.
5 MR. RECKLEY: Yeah. I'll be honest, this 6
didn't go through the technical editor, so I -- I was 7
putting -- I put it in a few places.
8 MEMBER BLEY: I just wanted to let you 9
know.
10 MR. RECKLEY: Okay. We added a sentence 11 on validation of computer codes. As I talked about, 12 you know, in this slide, there is -- we're laying out 13 a framework.
14 The assumption, inherent assumption, is 15 that all of this traditional work, like fuel 16 qualification, validation of computer models, really 17 everything you need to understand about the behavior 18 of the plant and the behavior of how radionuclides go 19 from one barrier to another or get stopped by a 20 barrier, all that work, scientific work, has to be 21 done to support the safety case.
22 We're just laying out kind of the 23 regulatory structure. All the technical work still 24 needs to get done to support the safety case argument.
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75 We did add one sentence. We had -- we had 1
alluded to we made it a little more clear that there 2
will be future papers coming out of the licensing 3
modernization project activities. Again, where --
4 where we're coming back to the ACRS in the summer to 5
talk about the general framework and some of the 6
things in more detail, our thinking is things like the 7
frequency consequence target figure, once we make a 8
move to say we're going to endorse it in a regulatory 9
guide, we want to at least make the Commission aware 10 of that.
11 It may be -- we haven't decided yet, but 12 it may be that we have to ask the Commission to weigh 13 in on that, so that we get something firm to move 14 forward on. So there's an understanding that this 15 will be the first paper and there will be a number of 16
-- at least one -- in all honesty, there will be any 17 number of papers that come out of this effort to go to 18 the Commission to weigh in on specific aspects of the 19 framework.
20 In a few places, we tried to change the 21 wording just a little bit to tweak it, in that there 22 were places we said the building -- should the 23 building have this function. And it's likely the 24 building is going to have some function in retaining 25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.
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76 radionuclides.
1 Once I build it, why would I not take 2
advantage of it in the analysis. And so -- so we 3
changed -- just tweaked the words to make it a little 4
more clear that it's likely that the enclosure would 5
serve -- would serve some purpose in at least some of 6
the event categories.
7 MEMBER KIRCHNER: I would recommend that 8
you add shielding. I think it's there, but now that 9
I look at it again, I don't see it.
10 MR. RECKLEY: Okay.
11 MEMBER KIRCHNER: At least it -- I don't 12 see it in the bowties list.
13 MR. RECKLEY: Okay. And then in terms of 14 the defense-in-depth discussion, we had a couple of 15 sentences. But the meat of it is here on the slide, 16 that the performance criteria are met without 17 exclusive reliance on a single element of a design or 18 a program. I don't know if that goes as far as -- as 19 you would propose. Probably not, but it --
20 MEMBER MARCH-LEUBA: No. I wanted 21 diversity independence.
22 MR. RECKLEY: Okay.
23 MEMBER MARCH-LEUBA: If you put two pieces 24 of paper, you have two but they are still the same 25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.
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77 thing. But it's a good try. It's a good try.
1 MR. RECKLEY: Part of the -- part of the 2
problem -- I'll be honest, part of the problem is when 3
you look at the spectrum of possible things we're 4
trying to address here, it makes it even difficult for 5
me to say straightforward anything that looks close to 6
-- to what full size the existing plant looks like, I 7
think no one would really argue the point, because as 8
you get smaller and smaller, I don't know that you 9
reach -- or some of these technologies, and we're 10 trying to make sure that we don't unnecessarily start 11 putting up restraints that may not be needed for some 12 designs. But that -- this will be a discussion that 13 we continue.
14 And then, so those are really kind of a 15 summary. Again, we didn't change very much from the 16 subcommittee.
17 And then, lastly, the recommendation stays 18 basically the same, that we're asking the Commission 19 to go ahead and approve the use of this kind of a 20 methodology to define the performance criteria for a 21 functional containment, and then we summarize that 22 approach or methodology in terms of the event 23 categories, and aggregating all of the credit that is 24 taken for any particular SSC. And then that becomes 25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.
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78 the performance criteria for the functional 1
containment for that design.
2 So that really is the end of the --
3 MEMBER MARCH-LEUBA: Can I make a 4
philosophical comment? You started this presentation 5
saying that one of the driving forces here was to 6
reduce the regulatory uncertainty, which is a very 7
good goal. I am worried that what we are adding here 8
is a lot of regulatory burden, because if you follow 9
this approach to the letter, you are going to have to 10 require a perfect PRA with extreme detail, full of 11 analysis, whereas the directors are expecting to write 12 a single piece of paper saying, "We don't melt the 13 core. We don't need nothing."
14 MR. RECKLEY: And we're having that 15 discussion. What -- if we can -- if we can lay out 16 that this -- that this general approach would work for 17 the whole set, if any particular developer can say, 18 for example, I don't want to do analysis of all of 19 this stuff, I want to, for example, go back to a 20 concept of maximum hypothetical accident and simply 21 say -- well, it's used -- the reason it comes up is 22 some of these reactors are getting in size comparable 23 to research reactors, and research reactors still use 24 a concept of maximum hypothetical accident that just 25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.
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79 says you take my inventory and treat it even non-1 realistically.
2 And I still don't get -- I still -- if any 3
developer wants to make a similar argument, my point 4
is they can make the argument and they can say, "Using 5
that most conservative maximum hypothetical accident, 6
I'm near zero, and that thing is way down there at 10 7
to the minus 7 or 8," and that's an argument that I 8
don't need to do much other assessments.
9 What we're -- what we're trying to weave 10 in is whether that's a different approach or it's a --
11 it's a different path within this same approach. And 12 we're still working with the industry to say how they 13 want to characterize that. Personally, I think --
14 MEMBER MARCH-LEUBA: Just make sure --
15 just make sure you don't preclude that simple 16 approach.
17 MR. RECKLEY: No, no. And as Amy 18 mentioned in the -- in the severe -- in the advanced 19 reactor policy statement, it's a goal that when you do 20 stuff simpler, the analysis and other aspects of the 21 licensing is also made simpler. You don't want to 22 have a simple design and then us not recognize it as 23 also supporting a simpler approach in terms of the 24 analysis and the licensing.
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80 So, yeah, we're -- we're cognizant.
1 MEMBER BLEY: Okay. Anything from the 2
members?
3 MEMBER RAY: Well, since I think we've got 4
a minute here, we can't start --
5 MEMBER BLEY: Well, there is something 6
else we can do.
7 MEMBER RAY: I see. All right.
8 MEMBER BLEY: But if you want to make a 9
speech, that's fine.
10 MEMBER RAY: I don't plan that. I just 11 want to take advantage of the time if we had it, but 12 if you've got something else to do, I want to just say 13 to Bill that there was a couple of times he made 14 comments that I wondered about, but I didn't want to 15 interrupt. And you talked about Chapter 15 items or 16 Chapter 15 analyses, things that we rely on being on 17 a cue list. A couple of times you mentioned tech 18 specs.
19 If somebody has operated plant -- I'm not 20 the only one here who has -- I just would like to be 21 sure that the import of having some things -- the 22 availability of something covered in tech specs is 23 understood, and there isn't just this continuum of, 24 oh, well, we'll set reliability goals and we have the 25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.
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81 maintenance rule and stuff like that, because it's a 1
world of difference between having something available 2
in accordance with the tech spec and having to have it 3
available on any other basis you want to think about.
4 MR. RECKLEY: Yes. The -- yes, there will 5
be those. The reason I hesitate or stammer here a 6
little bit is because -- because you know what's going 7
on in tech specs for operating reactors is -- as 8
things like completion times and other things are less 9
prescribed than they used to be.
10 And I don't want to say that approach 11 won't be taken here, but I will -- I will say there 12 will be limiting conditions for operations, and -- and 13 requirements in terms of availability in the tech 14 specs, maybe not as prescribed as they were originally 15 in light water reactors, this is way beyond the 16 discussions we're having yet with the community.
17 But the importance of that I share with 18 you is that I look at that as another defense-in-depth 19 kind of approach in that you're analyzing them 20 different, you're treating them somewhat different.
21 You know, one is over here in a reliability assurance 22 program; one is over here in tech specs, and you get 23 that kind of --
24 MEMBER RAY: Yeah. I mean, so often 25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.
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82 people think of things that are on a cue list as just 1
gold-plated. It's not necessary; it's a bunch of 2
crap. But when you're running a plant around the 3
clock, if it's a requirement -- and I'm not saying the 4
requirements should be as they were in the past -- but 5
if it's a requirement and you're going to get cited if 6
you fail to meet that requirement, it's a big 7
difference between that and what you assume about what 8
we now call Chapter 19, beyond design basis, FLEX 9
stuff, and all that. It's just a world of difference.
10 MR. RECKLEY: Right. All of the 11 discussions to date, that is maintained.
12 MEMBER BLEY: Thank you. Anything else?
13 Is there any -- yes, ma'am.
14 MEMBER DIMITRIJEVIC: I know you're not 15 going to be happy to see me talking about this, and 16 especially, you know, I can see history of the curve, 17 but looking -- and I saw it before. And to me, it 18 looks like, you know, this story about naked king and 19 nobody wants to say the king is naked. But actually 20 it's naked.
21 MEMBER BLEY: The Emperor's New Clothes.
22 MEMBER DIMITRIJEVIC: Well, the thing is, 23 this is not the PRA curve. If it's a PRA-related 24 curve, it should be really clear what event sequences 25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.
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83 we are talking about. Is that, you know, large 1
releases, the Level 3, Level 2, and they are not 2
really directly related to initiating events.
3 So if this is deterministic approach, 4
that's fine, and I am getting all related things. If 5
this is deterministic structure, that's a
6 deterministic structure. But then let's don't discuss 7
the PRA approach, and that's my point.
8 MEMBER BLEY: Is there anybody in the room 9
who would like to make a comment? Is the phone line 10 open? Ron, is there anybody on the phone line who 11 would like to make a comment? Please identify 12 yourself and do so.
13 Hearing no comments, I'm going to turn it 14 back to you -- no, I'm not. I'm going to -- I'd like 15 to go through my bullet points after we end this piece 16 of the session.
17 At this point, we're going to go off the 18 record and thank the staff for a great discussion.
19 (Whereupon, the above-entitled matter went 20 off the record at 3:18 p.m. and resumed at 3:49 p.m.)
21 CHAIR CORRADINI: Okay. We'll come back 22 into session. We'll take up our second topic of the 23 day, which is the WCAP 17938.
24 And Harold, do you want to lead us through 25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.
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84 this, please?
1 MEMBER RAY: Yes. Thank you, Mr.
2 Chairman. On February 7 the AP1000 subcommittee met 3
on this topic, WCAP 17938, Revision 2.
4 And we will now be presenting it here to 5
the full committee. The document is almost entirely 6
proprietary, as is the staff safety evaluation.
7 And therefore, we will conduct an open 8
meeting, which is what we're in now. We will take 9
following the Westinghouse and staff presentations, we 10 will take any public comments.
11 Then we will close the line. And the 12 remainder of the meeting will be closed to include 13 just those who are qualified to participate in the 14 discussion of the proprietary material.
15 I think that's the -- all I need to say by 16 way of introduction. Don, is there anything you 17 wanted to say before Westinghouse begins?
18 MR. HABIB: No. We're ready on the staff 19 side.
20 MEMBER RAY: Okay. Then in the interest 21 of time, I'll turn it over to Westinghouse. And 22 please proceed.
23 MR. SINHA: Okay. Good afternoon. My 24 name is Shayan Sinha. I work in the AP1000 licensing 25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.
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85 group.
1 And here with me is Zach Harper. He's a 2
manager of the AP1000 licensing group. And we're 3
representing Westinghouse and will be -- we're very 4
grateful also to be able to present this topic, WCAP 5
17938 to the ACRS full committee.
6 So, I just wanted to start by discussing 7
a little bit about the background of GSI 191. And 8
specifically the GSI 191 related design basis.
9 So as part of GSI 191 plans that are 10 required to place limits on debris inside containment.
11 And the purpose of these limits is to ensure that 12 following a LOCA that the debris doesn't result in 13 some cloggage.
14 It's part of the recirculation and long-15 term debris cooling. Long-term core cooling. So the 16 AP1000 actually significantly reduces many of the 17 limits compared to a lot of the generation two plants.
18 Essentially, this is because some of the 19 GSI 191 related learnings can be incorporated into the 20 design. And put into practice before construction and 21 operation.
22 One of the limits that is considerably 23 lower is the fibrous debris limit inside containment, 24 which is 6.6 pounds per the AP1000 DCD. All this 25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.
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86 fibrous debris is attributable to latent debris.
1 So in other words, following the LOCA, the 2
expectation is that no debris will be generated 3
because of the LOCA.
4 MEMBER RAY: Well, and let me just quibble 5
a little. I guess I would say it's a requirement, at 6
least as far as we're concerned in this proceeding.
7 MR. SINHA: Correct. And that's how we're 8
treating it again, in our evaluation of this topic.
9 MEMBER RAY: Yeah. That's right.
10 MR. SINHA: The metallic reflective 11 insulation is used extensively inside containment 12 including on the reactor vessel itself. And the DCD 13 and the Vogtle FSAR provide requirements that must be 14 demonstrated if you want to use an alternative fibrous 15 debris rather as opposed to MRI.
16 And these requirements include that we 17 need to demonstrate that this alternative insulation 18 is a suitable equivalent for the purposes of GSI 191.
19 There needs to be testing that will 20 demonstrate that this alternative insulation is a 21 suitable equivalent to metallic reflective insulation.
22 And will not generate debris or transport debris. And 23 also that the testing must be approved by the NRC.
24 So the purpose of WCAP 17938 is three 25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.
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87 items. The first item is we wanted to establish a 1
zone of influence applicable to all AP1000 in 2
containment cabling that would demonstrate that it 3
would not produce debris following a LOCA.
4 We wanted to gain approval that 5
nonmetallic insulation used in the reactor insulation 6
system for AP1000 is a suitable equivalent to MRI for 7
the purposes of GSI 191. And we also wanted to gain 8
approval to utilize NEI 04-07 alternate methodology 9
for defining debris generation break sizes.
10 Which is a methodology that is approved 11 generically in the NEI 04-07 safety evaluation.
12 However, it was not previously applied to AP1000 13 specifically.
14 And essentially the testing analysis that 15 I'm going to describe is -- helps us demonstrate that 16 neither in the cabling nor the nonmetallic insulation 17 would contribute to post-LOCA debris.
18 MEMBER MARCH-LEUBA: Shayan, can you 19 shortly for the record, tell us whether these are 20 post-core cables? So if a cable has to penetrate the 21 zone of influence, what happens?
22 MR. SINHA: So the -- essentially we would 23 have to protect it. We'd have to incorporate a 24 protection scheme that we think would prevent it from 25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.
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88 producing debris.
1 So yeah, I think that's something that's 2
noted in the topical report that it's not specifically 3
approved in the topical report. But essentially 4
that's a criteria for cable that would go unprotected, 5
is the 4D ZOI.
6 However, if it's inside the 4D ZOI, then 7
we would have to come up with a different protection 8
scheme.
9 CHAIR CORRADINI: So, can you slow down 10 and say that again?
11 MR. SINHA: Sure.
12 CHAIR CORRADINI: So that if it's inside 13 the zone of influence, it has to be protected?
14 MR. SINHA: Yes. That's correct.
15 CHAIR CORRADINI: Okay. Fine. And if 16 it's outside, based on some methodology, it remains 17 however it's normally -- the cable is normally 18 supported in and installed?
19 MR. SINHA: Yes.
20 CHAIR CORRADINI: Okay. Great. Thank 21 you.
22 MEMBER RAY: Let me just add one little 23 thing here too actually in the staff safety 24 evaluation. It's the responsibility of the licensee 25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.
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89 to, and they use the term various methods for 1
providing protection, to demonstrate the adequacy of 2
the protection provided within the zone of influence.
3 So, it's agreed outside the scope of what 4
we're dealing with here.
5 MR. SINHA: Slide please. So a little bit 6
of background of how this topical report came about.
7 There were two items that essentially led to the 8
creation of WCAP 17938.
9 The first item was that an issue was 10 uncovered that the cabling inside the AP1000 11 containment may contain fibers and other materials --
12 fibrous materials and other materials that could 13 potentially be debris. But it was not -- were not 14 sufficiently evaluated previously as debris sources.
15 So, as part of the resolutions issue, 16 corrective actions were taken. And they included the 17 development of a test program to establish a zone of 18 influence for in containment cabling.
19 The second item is that nonmetallic 20 insulation is required in the reactor vessel 21 insulation, because they are components that perform 22 functions beyond the insulation function.
23 So for example, the three subcomponents 24 are locations that are in the scope of this topical 25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.
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90 are shown in that figure to the right. And the CA 31 1
module, neutron shielding blocks are there for neutron 2
shielding function.
3 They prevent neutron streaming upwards in 4
the containment. The lower neutron shield is there to 5
prevent neutron streaming into the reactor cavity to 6
reduce some of the dose in the reactor cavity in the 7
lower portions of containment.
8 And then the water inlet doors support the 9
in-vessel retention function for the -- for the beyond 10 basis accident scenarios.
11 CHAIR CORRADINI: Can you point to those 12 again? I'm sorry.
13 MR. SINHA: The water inlet --
14 CHAIR CORRADINI: Well, you have the 15 mouse. And you can do the mouse.
16 MR. SINHA: Right. So the water inlet 17 doors are here.
18 CHAIR CORRADINI: Oh, okay. Thank you.
19 MR. SINHA: Yeah, so those are there to, 20 you know, they need to allow water in like following 21 a severe basis accident and when we are demonstrating 22 the in-vessel retention capabilities.
23 So, some of the summaries of the results 24 of our program that we -- that evaluated these 25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.
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91 nonmetallic insulation cables. So there was extensive 1
large-scaled jet impingement testing that was 2
performed to establish the zone of influence for in 3
containment cables of 4 L/D.
4 This testing was performed at a laboratory 5
that was used previously for a Pressurized Water 6
Reactor Owners Group in their establishing of the zone 7
of influence for other operating plants.
8 And essentially this 4 L/D ZOI was 9
incorporated in as a design requirement, as a design 10 criteria, as we evaluated the routing cables inside 11 containment in advance of actually installing any 12 cable or cable tray.
13 The WCAP invokes the alternate evaluation 14 methodology from NEI 04-07 to determine the minimum 15 break size when considering debris generation break in 16 AP1000 components. And then the insights from the 17 nonmetallic insulation, jet impingement, and 18 submergence testing programs resulted in design 19 changes that strengthen elements of the second points 20 of the reactor vessel insulation.
21 So essentially the design was changed to 22 use thicker and more robust encapsulation methods. So 23 essentially, as part of these programs, we were -- the 24 WCAP justified that no new debris was generated from 25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.
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92 the AP1000 cabling for nonmetallic insulation.
1 And then finally, so our conclusions. So 2
a zone of influence of 4 ID is applicable to the 3
AP1000 in containment cabling founded by testing 4
analysis.
5 The application of the NEI 04-07 alternate 6
break methodology was acceptable for use in AP1000.
7 And the cabling does not contribute to AP1000 post-8 LOCA debris limits.
9 With regards to the nonmetallic 10 insulation, the encapsulated nonmetallic insulation 11 used in the AP1000 reactor vessel insulation, would 12 not produce debris when subjected to jet impingement 13 from limiting line breaks.
14 And then neither the cabling nor the NMI 15 was found to contribute to the chemical debris when 16 it's imposed by GSI 191.
17 And then
- finally, based on the 18 consideration of the submergence testing and the jet 19 impingement testing and analysis, the conclusion was 20 that the nonmetallic insulation used in the reactor 21 vessel insulation is suitable equivalent to MRI for 22 the purposes of GSI 191.
23 And just to kind of reiterate the overall 24 conclusion that the WCAP justifies that there's no new 25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.
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93 debris generation for AP1000 cabling for nonmetallic 1
insulation.
2 MEMBER RAY: Questions? On this segment.
3 Okay.
4 MEMBER SUNSERI: I had one. Just one 5
question.
6 MEMBER RAY: Yeah. Sure, go ahead.
7 MEMBER SUNSERI: So I don't -- I remember 8
we had the discussion. But I don't remember the 9
outcome during the subcommittee meeting.
10 But, -- so the cables that were tested, I 11 mean different manufacturers will have different 12 insulation systems, different filament material, et 13 cetera.
14 So, is this evaluation for that specific 15 manufacturer for zone of influence of 4? Or is it a 16 generic cable?
17 MR. SINHA: So, the -- essentially the --
18 well, we -- yeah, this cabling that we used from this 19 vendor is a benchmark of sorts.
20 And we've added wording into the DCD 21 markup that says that it's a 4D of ZOI is applicable 22
-- it's essentially that the bullet that's there that 23 says it's applicable to AP1000 containment cables 24 founded by testing and analysis.
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94 And I think -- I believe the staff has 1
added some wording to the safety -- to the revised 2
safety evaluation saying that really if, you know, it 3
would need, the cable would need to be reassessed if 4
there's a change in vendor.
5 So, I think the staff could expand on that 6
more when they have their discussion. But, as an 7
outcome of that comment from the last two meetings, 8
those two changes were considered and made and we're 9
moving forward with the topical.
10 MEMBER RAY: We'll follow up on that a 11 little bit in the impression part of the meeting.
12 Anything else?
13 (No response) 14 MEMBER RAY: Okay. Thank you very much.
15 We will now ask the staff to come and give their 16 corresponding presentation.
17 And then as I said at the beginning, we'll 18 seek any comments that members of the public may have.
19 Please proceed when you're ready.
20 MR. HABIB: Good afternoon. My name is 21 Don Habib. I've been serving --
22 MEMBER RAY: Don, I question if you have 23 your microphone on. Or if it's close enough to you.
24 There you go.
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95 MR. HABIB: Now we're good. Better.
1 Thank you.
2 Good afternoon. My name is Don Habib.
3 I've been serving as the project manager for the staff 4
review of this technical report.
5 And I'm joined by Clint Ashley and Boyce 6
Travis, who are members of the technical review team.
7 And we'd like to thank you for the opportunity to 8
present the draft safety evaluation topical report.
9 And look forward to answering your 10 questions either in this public session or in a closed 11 session for any proprietary matters.
12 Since the subcommittee meeting on February 13 7, the staff had made changes to the draft safety 14 evaluation. And we've provided that revised draft to 15 the subcommittee.
16 The staff inserted additional information 17 partly in consideration of remarks from the 18 subcommittee meeting. And we also revised it to 19 address the change to the topical report submitted by 20 Westinghouse.
21 And so in the next few minutes I'll 22 provide an overview of the staff's review. And after 23 that, Clint will talk about those key changes that we 24 made.
25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.
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96 The technical review team includes Clint 1
Ashley, Boyce Travis, as well as Renee Li, Greg Makar, 2
and Malcolm Patterson. They're all from the Office of 3
New Reactors.
4 We also worked with our counterparts in 5
the Office of Nuclear Reactor Regulation. So they 6
also participated in the review.
7 As background, this topical report is a 8
document that addresses a technical topic related to 9
power plant safety. And these topical reports, they 10 address generic issues.
11 They can affect multiple plants. And are 12 intended to help make the licensing change process 13 more efficient for those plants.
14 For example, when multiple plants will be 15 addressing the same licensing issue. In this case the 16 topic relates to GSI 191 and examines the assessment 17 of debris and PWR sump performance.
18 And this topical report is specific too 19 just the AP1000 design. So approval of -- a staff 20 approval of this report would allow AP1000 licensees 21 to use this in support of future licensing changes.
22 The AP1000 design as it's currently 23 certified states that a loss of coolant accident, or 24 LOCA, in the AP1000 does not generate fibrous debris 25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.
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97 due to damage to insulation or other materials in the 1
AP1000 design.
2 Instead of using fibrous insulation around 3
pipes and components, the AP1000 design uses metal 4
reflective insulation. Which does not generate debris 5
during the LOCA.
6 The AP1000 again, the design allows for 7
substituting other materials that are considered 8
suitable equivalents to metal reflective insulation.
9 If the testing shows that they do not generate or 10 transport debris, and if that testing is approved by 11 the staff.
12 This topical report seeks NRC approval for 13 three items related to the potential generation of 14 debris. First it requests that a zone of influence be 15 established for electrical cabling and containment.
16 The AP1000 as it's currently certified 17 does not explicitly address cabling and cable 18 insulation. Or the generation of debris from cable.
19 And so this topical report, under this 20 certain cables could be used in containment if they 21 are located outside the defined zone of influence.
22 Second, the report requests NRC approval 23 for the use of nonmetallic insulation as a suitable 24 equivalent to metal reflective insulation at certain 25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.
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98 locations within containment.
1 And as previously mentioned, the use of 2
metal reflective insulation is a key design feature of 3
the AP1000 design that supports a generation of zero 4
debris in containment.
5 Finally, the report requests NRC approval 6
of the use of NEI 04-07 PWR sump performance 7
evaluation methodology. Which requests -- which 8
provides an alternative methodology for plant specific 9
evaluation of sump performance.
10 And that's already been approved by the 11 NRC. And this would allow it to be applied 12 specifically for the AP1000 design.
13 The main guidance that staff used in 14 support of the evaluation included the NEI 04-07, as 15 well a -- the staff safety evaluation that's written 16 in approval of the NEI 04-07.
17 In addition, it included WCAP 16530, 18 evaluation of post-accident chemical effects in 19 containment sump fluids to support the PSI 191. And 20 that takes the evaluation a further step, looking at 21 chemical affects in addition to debris.
22 MR. ASHLEY: Hi. I'm Clint Ashley. These 23 are just some of the updates that we made to the WCAP 24 and the associated safety evaluation.
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99 So when the subcommittee meeting was held 1
on February 7, 2018, there was some discussion amongst 2
the members about the potential for replacement cables 3
to have a different construction and possibly 4
performance when it came to zone of influence.
5 So in response to that, the applicant did 6
strengthen the WCAP. And in particular that language 7
that's incorporated in -- that will be incorporated by 8
a licensee who adopts this WCAP.
9 In their updated final safety analysis 10 report will clarify that that ZOI radius applicable to 11 AP1000 in containment cables is bounded by the testing 12 and analysis that's presented in the WCAP.
13 So that was one area that the applicant 14 strengthened their WCAP. And in response to that same 15 overall comment, the staff added a limitation.
16 And we recognize that there could be new 17 or evolving cable designs that may have different 18 cable construction. And these cables may exhibit a 19 different zone of influences.
20 So the licensee or an applicant would need 21 to evaluate those cable design changes to ensure that 22 those new designs don't impact adequate and long term 23 core cooling.
24 We also clarified a comment that Dr. Rempe 25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.
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100 had made, on the WCAP used the reference towards an 1
ACRS letter when it talked about chemical affects and 2
cables. So we clarified some of the language in the 3
SE that talked about how the staff actually used that 4
WCAP reference. Next slide.
5 In summary the staff reviewed the three 6
items presented in the WCAP, and summarized on this 7
slide. In the draft safety evaluation, the staff 8
finds the approach described in the WCAP acceptable.
9 And approves and requests subject to 10 limitations and conditions. I just sited a new 11 limitation and condition that we added on the previous 12 slide.
13 Just for rec -- to recall, we also talked 14 about a limitation and condition about performance of 15 cables within the zone of influence was outside the 16 scope of the WCAP.
17 We also have a limitation on the quantity 18 of aluminum in containment. We also have a 19 limitation. It talks about the evaluation of the 20 neutron shield block.
21 We didn't evaluate it for its neutron 22 performance or shielding performance. It was merely 23 an evaluation to look at it from a GSI 191 24 perspective, a debris generation perspective.
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101 And I think that covers most of the 1
limitations. That concludes the staff's presentation.
2 MEMBER RAY: Thank you Clint. Okay.
3 Questions on this phase of the staff's presentation 4
before we move onto the closed session?
5 (No response) 6 MEMBER RAY: Okay. And now then I will 7
have to pause for a bit and ask for the comments that 8
members of the public may have who are either here in 9
the room. Are there any in the room who wish to make 10 a comment?
11 (No response) 12 MEMBER RAY: If not, then I'll make a 13 similar request to anyone on the telephone line. I'm 14 assured that it's open. And if --
15 MR. BROWN: The line is open.
16 MEMBER RAY: Thank you Theron. If there 17 is anyone who would like to make a comment, please 18 merely identify yourself and make your comment.
19 (No response) 20 MEMBER RAY: Nothing then. In that regard 21 we'll close the line and enter the proprietary section 22 of the meeting today.
23 And in this case I'll ask that 24 Westinghouse and staff verify that the room is 25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.
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102 occupied only by those who are authorized to 1
participate or observe the proprietary discussion.
2 (Whereupon, the above-entitled matter went 3
off the record at 4:12 p.m.)
4 5
6 7
8 9
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Presentation to the ACRS Full Committee Draft Safety Evaluation AP1000 In-Containment Cables and Non-Metallic Insulation Debris Integrated Assessment WCAP-17938-P, Revision 2 April 2018
Presentation Topics
- Introduction
- Overview
- Updates
- Summary 2
Introduction
- NRC Technical Reviewers Clint Ashley Containment and Ventilation Branch Boyce Travis Containment and Ventilation Branch Renee Li Mechanical Engineering Branch Greg Makar Materials & Chemical Engr. Branch Malcolm Patterson PRA and Severe Accidents Branch
- NRC Project Manager Don Habib Licensing Branch 4 3
Introduction (contd)
- A topical report is a document that addresses a technical topic related to nuclear power plant safety.
- In topical report WCAP-17938, Westinghouse updates the AP1000 plant safety analysis related to Generic Safety Issue 191 (GSI-191).
- Westinghouse seeks review and approval of WCAP-17938 by the U.S. Nuclear Regulatory Commission (NRC) for use in the licensing process by AP1000 licensees.
4
Overview
- The AP1000 design basis in part states that a LOCA in the AP1000 does not generate fibrous debris due to damage to insulation or other materials included in the AP1000 design,
- As such, the WCAP seeks NRC approval for three items:
- 1. A zone of influence (ZOI) for electrical cabling in containment.
- 2. Use of non-metallic insulation (NMI) as a suitable equivalent to metal reflective insulation (MRI).
- 3. Use of NEI 04-07 alternate evaluation methodology to assess debris generation.
5
Overview (contd)
- Main guidance for evaluating WCAP-17938:
Nuclear Energy Institute (NEI) 04-07, PWR Sump Performance Evaluation Methodology Safety Evaluation for NEI 04-07, PWR Sump Performance Evaluation Methodology WCAP-16530-NP-A, Evaluation of Post-Accident Chemical Effects in Containment Sump Fluids to Support GSI-191 6
- ACRS Subcommittee meeting held on February 7th 2018.
Identified the potential for replacement cables to have a different construction and performance (i.e., ZOI).
- In response, the applicant strengthened the WCAP:
ZOI radius is applicable to the AP1000 in-containment cables bounded by testing and analysis...
- In response, the staff added a limitation:
Because new or evolving cable designs may have a different cable construction that could exhibit a different ZOI, licensees or applicants must evaluate cable design changes to ensure that new designs do not impact adequate long term cooling.
- Staff also clarified the SE discussion (Section 3.2) on references used for assessing chemical effects due to cables.
7
Summary
- The WCAP requests staff review and approval for three items:
the application of the proposed ZOI for cables the determination that NMI located in the reactor vessel cavity is a suitable equivalent insulation the application of the alternate evaluation for debris assessment
- The staff finds the approach described in the WCAP acceptable and approves the requests, subject to limitations and conditions.
8
Westinghouse Non-Proprietary Class 3
© 2018 Westinghouse Electric Company LLC. All Rights Reserved 2
WCAP 17938 Revision 2, ACRS Full Committee Meeting April 5, 2018 Zachary Harper Shayan Sinha APP-GW-GLY-153, Revision 0
- This record was final approved on 3/28/2018 11:44:08 AM. (This statement was added by the PRIME system upon its validation)
- This record was final approved on 3/29/2018 11:12:11 AM. (This statement was added by the PRIME system upon its validation)
3 Westinghouse Non-Proprietary Class 3
© 2018 Westinghouse Electric Company LLC. All Rights Reserved.
Background
AP1000 GSI 191 Design Bases AP1000 design significantly reduces / eliminates debris sources that are typically found in Generation II plants Maximum allowable fibrous debris inside containment is 6.6 lbs
- All fibrous debris is attributable to latent debris
- There is no fibrous debris generated during a LOCA Metal reflective insulation (MRI) is extensively used in containment DCD/FSAR provides requirements that must be demonstrated if an alternative (fibrous) insulation to MRI is utilized Insulation must be demonstrated to be a suitable equivalent insulation to MRI for the purposes of GSI 191 To qualify a suitable equivalent testing must be performed to demonstrate that debris will not be generated or transported Suitable equivalent testing must be approved by the NRC APP-GW-GLY-153, Revision 0
- This record was final approved on 3/28/2018 11:44:08 AM. (This statement was added by the PRIME system upon its validation)
- This record was final approved on 3/29/2018 11:12:11 AM. (This statement was added by the PRIME system upon its validation)
4 Westinghouse Non-Proprietary Class 3
© 2018 Westinghouse Electric Company LLC. All Rights Reserved.
Background
WCAP 17938 Purpose Purpose of WCAP 17938 is to obtain approval of the following:
1.
Establish a zone of influence (ZOI) applicable to all AP1000 plant in-containment cabling to demonstrate cabling will not generate LOCA debris 2.
Gain approval that the non-metallic insulation (NMI) utilized in the reactor vessel insulation systems (RVIS) is a suitable equivalent to MRI for the purpose of GSI 191 as applied in AP1000 3.
Gain approval to utilize the approved NEI 04-07 alternative methodology for defining debris generation break sizes for AP1000 Testing and analysis is complete to demonstrate that neither cabling nor NMI will contribute to post LOCA debris APP-GW-GLY-153, Revision 0
- This record was final approved on 3/28/2018 11:44:08 AM. (This statement was added by the PRIME system upon its validation)
- This record was final approved on 3/29/2018 11:12:11 AM. (This statement was added by the PRIME system upon its validation)
5 Westinghouse Non-Proprietary Class 3
© 2018 Westinghouse Electric Company LLC. All Rights Reserved.
Background
WCAP 17938
- AP1000 cabling may contain fibrous and other materials that were not considered in initial GSI 191 debris source term evaluations
- Corrective actions included development of a test program to establish a ZOI for in-containment cabling
- NMI is required in RVIS because subcomponents of the RVIS perform functions in addition to insulation (such as shielding and in-vessel retention support)
CA31 LNS Water Inlet Doors APP-GW-GLY-153, Revision 0
- This record was final approved on 3/28/2018 11:44:08 AM. (This statement was added by the PRIME system upon its validation)
- This record was final approved on 3/29/2018 11:12:11 AM. (This statement was added by the PRIME system upon its validation)
6 Westinghouse Non-Proprietary Class 3
© 2018 Westinghouse Electric Company LLC. All Rights Reserved.
Summary of Results WCAP justifies no new debris generation for AP1000 from cabling or NMI
- Extensive large scale jet impingement testing established a ZOI for in-containment cables of 4 L/D
- Cabling ZOI design requirements were incorporated into the detailed design in advance of any cable or tray installation
- WCAP invokes the alternate evaluation methodology provided in NEI 04-07 to determine a limiting RCS break size in debris generation evaluation for certain AP1000 components
- Insights from NMI jet impingement and submergence testing resulted in strengthening design for elements of the RVIS
- Design was changed to use thicker and more robust encapsulation APP-GW-GLY-153, Revision 0
- This record was final approved on 3/28/2018 11:44:08 AM. (This statement was added by the PRIME system upon its validation)
- This record was final approved on 3/29/2018 11:12:11 AM. (This statement was added by the PRIME system upon its validation)
Westinghouse Non-Proprietary Class 3
© 2018 Westinghouse Electric Company LLC. All Rights Reserved 7
Conclusions APP-GW-GLY-153, Revision 0
- This record was final approved on 3/28/2018 11:44:08 AM. (This statement was added by the PRIME system upon its validation)
- This record was final approved on 3/29/2018 11:12:11 AM. (This statement was added by the PRIME system upon its validation)
8 Westinghouse Non-Proprietary Class 3
© 2018 Westinghouse Electric Company LLC. All Rights Reserved.
Conclusions
- A ZOI radius of 4 IDs is applicable to the AP1000 in-containment cables bounded by testing and analysis
- Application of NEI 04-07 alternative break methodology is acceptable for AP1000
- Cabling does not contribute to AP1000 post LOCA debris limits
- Encapsulated NMI applications utilized within the AP1000 RVIS will not produce debris when subjected to jet impingement from limiting line breaks
- Neither cabling nor NMI within the RVIS contribute to GSI 191 chemical debris limits
- NMI utilized as part of the RVIS is a suitable equivalent to MRI for the locations bounded by testing and analysis (for the purpose of GSI 191)
WCAP justifies no new debris generation for AP1000 from cabling or NMI APP-GW-GLY-153, Revision 0
- This record was final approved on 3/28/2018 11:44:08 AM. (This statement was added by the PRIME system upon its validation)
- This record was final approved on 3/29/2018 11:12:11 AM. (This statement was added by the PRIME system upon its validation)