ML20246D358
| ML20246D358 | |
| Person / Time | |
|---|---|
| Issue date: | 05/02/1989 |
| From: | NRC COMMISSION (OCM) |
| To: | |
| References | |
| REF-10CFR9.7 NUDOCS 8905100204 | |
| Download: ML20246D358 (80) | |
Text
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y UNITED STATES OF AMERICA NUCLEAR REGULATORY COMMIS SION l
s 7: e 1..
1 '- C '
BRIEFING ON SEVERE ACCIDENT RESSARCH PLAN l
LOCatiOL:
ROCxv1LLE, MARYLAND h3I6:
MAY 2, 1989
?3g6S:
51 PAGES NEALR.GROSSANDCO.,.INC.
COURT BEPORTERS AND TRANSCRIBERS 1323 Rhode Island Avenue, Northwest Washington, D.C.
20005 (202) 234-4433 l
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i 9 "1 8905100204 890502 I
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0 6
C DISCLAIMER This is an unofficial transcript of a meeting of the United States Nuclear Regulatory Commission held on May 2, 1989 in the Commission's office at one White Flf nt North, Rockville, Maryland.
The meeting was open to public attendance and observation.
This transcript has not been reviewed, corrected or edited, and it may contain inaccuracies.
The transcript is intended solely for general informational purposes.
As provided by 10 CFR 9.103, it is not part of the formal or informal record of decision of the matters discussed.
Expressions of opinion in this i
transcript do not necessarily reflect final determination j
or beliefs.
No pleading or other paper may be filed with I
l the Commission in any proceeding as the result of, or I
addressed to, any statement or argument contained herein, 1
except as the Commission may authorize.
i 1
}
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NEAL R. GROSS court RepoRTWt3 AND TRANSCRIBER 5 1323 RHOOE ISLAND AVENUE, N.W.
(202) 234-4433 WASH 0NGTON, D.C.
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1 UNITED STATES OF AMERICA 2
NUCLEAR REGULATORY C'OMMISSION 3
1 4
BRIEFING ON SEVERE ACCIDENT RESEARCH l
~
5 PLAN
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I 6
f 7
PUBLIC MEETING I
8 9
Nuclear Regulatory Commission 10 One White Flint North
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11 Rockville. Maryland 12
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i 13 Tuesday, May 2, 1989
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14 3
4 15 The Commission met in open session, pursuant to 1
16 notice, at 10:00 a.m.,
the Honorable LANDO W.
- ZECH, JR.,
j
(
l 17 Chairman of the Commission, presiding.
18 I
19 COMMISSIONERS PRESENT':
o 20 LANDO W.
- ZECH, JR., Chairman of the commission
)
21 THOMAS M. ROBERTS, Member of the Commission 1
l 22 KENNETH C. ROGERS, Member of the Commission
)
23 JAMES R.
CURTISS, Member of the Commission I
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i STAFF AND PRESENTERS SEATED AT THE COMMISSTON TABLE:
2 SAMUEL J.
CHIif. secretary 3
STUART TPEBY General Counsel's Office 4
VICTOR STELLO. JE.
Executive Director for Operations 5
EPIC BECKJORD, Director. Office of Research 6
BPIAN SHERON. RES 7
FRANK COSTAMZT. PES 1
i 8
DENNY ROSS, RES j
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PRgCEED I fl G S 2
(10:04 a.c.)
1 C H A I P M A ti 7,E C H -
Gnad morning.
ladies and 4
gentlemen.
5 Commissioner Carr will not be with us today.
6 This is an information briefing in which the 7
Office of Research will describs its revised severe 8
accident research program plan.
Details of the revised 9
plan are described in a recent flRC staff paper, SECY 89-in 1:3.
11 The severe accident research program provides 12 confirmatory information and technical support in 13 implementing the IIR C integration plan for closure of 14 severe accident. issues.
That plan was described in an 15 earlier staff paper. SECY 88-147, and has been the subject 16 of several Commission meetings.
17 Copies of the slide presentation and the staff's 18 paper, SECY 89-123, should be available at the entrance to 19 the meeting room.
20 Do any of my fellow Commissioners have any 21 opening comments before we begin?
22 (tio response.)
23 If not, Mr. Stello, you may proceed.
24 MR. STELLO:
Thank you, Mr. Chairman.
I wanted 25 to take a moment to review some of the background of the l
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research activity.
As you are aware, a great deal cf the
+.
.4 2
work that comes out of the agency starts with research.
3 Some it spanned many years cnd nvolved the expenditures 4
of very large sums of money.
auch as emergency core 5
cooling that spanned probe.bly the better part of 20 years.
6 We finally resolved that issue and at very large 7
expenditure of funds.
Other issues which have gone on for 8
quire some time and are very, very significant in terms of 4
dealing with safety issues such as PTS.
10 When we provided you with our integration plan 11 for closure of severe accidents, it was apparent then that 12 this was pretty much dictating, in a general sense, the 13 strategy of where the severe accident research ought to go 14 and, at that ti me. the Commission, at that meeting and in 15 document.s since that time, has indicated the need to have 16 a status and an update and a briefing of the Commission of 17 the general thrust of where we ought to go.
l l
18 Eric and his staff have done what I think is a 19 very commendable job in trying to lay out the framework 20 for that program; have gone out and sought comment and 21 review by various organizations, trying to make sure that 22 what we are now doing is, in fact, viewed by those who j
1 i
23 normally review it, such as the ACRS and our peer review j
24 group for research, indicates to us at least our belief 25 that we are, in fact, on the right track.
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i And what we want to do today is to brief the 2
Cemnission on whera we are with respect to the progran, 3
and we'll brief you in rorms of whars we inr.end to go both a
in the long-rerm as well as the ahort-term, filling the 1
5 more immediare needs that we have for the IFF, CPI, the 6
containment performance and the plant performance, as well 7
as our accident management safety goal.
And with that 8
brief introduction, let me ask Eric to have some opening 4
remarks, and we'll get into the meat of the briefing.
10 CHAIRMAN ZECH:
All right.
Thank you very much.
11 You may proceed.
12 MR. BECKJORD:
Thank you, Mr. Chairman.
13 On April 13th, I reported to you on carrying out 14 the integration plan for the closure of severe accident 15 issues document that you've already referred to.
16 The revised severe accident research program 17 plan is an important element of the closure plan, and 18 today we are presenting it to you in detail.
19 Specifically, the severe accident research program 20 provides a technical base for support of the other l
21 elements of the closure plan.
22 The severe accident research program has four 23 goals.
- First, to provide new knowledge for assessing 24 containment performance over the range of risk-significant l
l 25 core melt events; secondly, to evaluate the effectiveness (2021234-4433 IIEAL R.
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of generic containment performance improvements: third, to 2
support the development of generic accident management 3
procedures:
and
- fourth, to assess fission product 4
hehavior and release in severe accidents in the event of 5
containment failure.
i 6
It focuses on the resolution of severe accident 7
issues having high risk significance in the near-term, 8
especially the containment performance questions.
9 The long-term part of the program aims at 10 reducing the uncertainties in the knowledge of severe
~1 accident phenomena.
This will help to reduce the 12 uncertainties in future probablistic risk assessments.
13 The revised severe accident research program was 14 developed with input from experts in the university, the 15 national Inboratory. and the industrial community.
The 16 performers of the research, university people and the NRC 17 program offices. have reviewed the plan.
The Advisory 18 Committee on Reactor Safeguards has strongly supported the 19 plan.
Also, our Nuclear Safety Research Review Group has l
20 reviewed the plan, under Professor Todreas.
I strongly 21 recommend to you this plan.
22 CHAIRMAli ZECH:
Thank you very much.
23 DR.
SHERON:
Could I have the first slide, 24 please.
25 CHAIRMAN ZECH:
You may proceed.
Thank you.
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1 DR.
SHERON:
(Slide)
Just to repeat.
the I
L -
2 objectives of the research program are -- just a different 3
form than what Eric just said -- is to develop a technical 4
base of severe accident information, which could be used 5
by the Commission and the staff, in any and all actions 6
- r. hat are taken related to severe accidents; also, to 7
support by developing a technical base, the various 8
actions already underway -- the IPE, the containment 9
performance program, or accident management.
10 And another one, the last one here, is to 11 basically help develop an understanding of plant response 12 to severe accidents, to make sure there are no unexpected 13 phenomena that would change our perception of risk.
i L_
14 Could I have the next slide.
(Slide)
In 15 setting out to develop this revised plan, keep in mind 16 that severe accident research has been underway in this 17 agency about ten years.
la Our underlying motive was to make sure that the 19 research was consistent with the integration plan,88-147, 20 We also wanted to make sure this was not just something 21 that was dreamed up by the staff, but had the support of 22 the technical community.
And what we did is, we tried to 23 draw unon a broad spectrum of expertise across the nation.
24 We called on experts from the national labs, I
25 industry, universities, and the experts within the staff, (202)234-4433 NEAL R.
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to help identify how the current research activities in 2
severe, accidents were related to SECY 88-147.
3 We broke these experts into three groups, 4
basically functional, and asked them to look at the 5
ongoina research and how it related, and to provide the 6
results to a senior oversight group.
This was made up of i
7 staff manacement Dr. Costanzi headed it -- as well as 8
senior managers from the laboratories and university 9
community.
10 This oversight group helped assimilate all this 11 information from these three groups, and helped focus it 12 in the proper direction.
The staff then took the results 13 from this oversight group and went to work in developing a j
i 14 plan. So, this was the basic approach to developing this.
15 Could I have the next slide, please.
(Slide) 16 We also used IIUREG 1150 as a guidance document, in 17 defining and ranking severe accident issues.
As you know, i
18 1150 pulled together a lot of experts in terms of looking 19 at what the uncertainties were and what the importance for 20 various phenomena in determining risk, and we made sure 21 that we used that information to the fullest.
22 Once we had developed a plan, we circulated it 23 widely for comment, to the national labs, again; the 24 universities: EPRI; Dr. Todreas' committee, the Research 25 Review Committee: and the ACRS.
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1 We were encouraged because almost all the
[_
2 comments we got back were virtually all favorable on the I
i 3
plan, that it was in the right direction, had the right 4
elements to it, and the ACRS was particularly encouraging.
5 COMMISSIONER ROBERTS.
That's a
major 6
accomplishment.
7 DR.
SHERON:
Could I have the next slide.
8 please.
(Slide)
This you've seen before, is the 9
schematic of the severe accident program.
It's just here 10 to remind you where the research program fits in in the 11 overall closure process.
You'll see it down in the lower, 12 right corner.
You'll see that it's principally designed 13 to contribute to the containment performance improvements, u -.
14 as Eric said.
It does feed into both the IPE process as 15 well as accident management, and you'll notice that the 16 arrow continues, which means there will be a longer-term 17 confir:ratory research program even beyond closure.
18 CHAIRMAN ZECH:
Before you go off that one, it 19 seems to me that's very important.
Could you be a little 20 bit more specific on how the research that -- described in 21 that schematic, could impact on the IPE program -- in 22 other words, in identifying vulnerabilities, or any 23 accident management, or containment improvements that you 24 might be considering?
How does that really affect the IPE I
25 program?
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DR. SHERON:
It affects it in a number of ways.
2 I guess the most striking example I could give you is that 3
the Electric Power Research Institute approached me about 4
four or five months ago, and asked if they might conduct 5
an independent review of a severe accident computer code, 6
BWPSAR. that was developed by Oak Ridge.
7 We gave them our blessing to go forth and do 8
that, and my understanding is that they were trying to put 9
together analysis capability for the utilities so that 10 they could do their IPE analysis.
11 We've also had requests for other of our 12 analysis codes which, again, are incorporating the latest 13 technology from research, so that they could use these for 14 conducting the IPE.
15 So, the principal impact that we are having on 16 the IPE is that the technology we are developing which, in 17
- turn, gets embodied in our analysis computer codes, is la being picked up and used directly by the utilities in 19 conducting the IPE, the back-end analysis.
20 CHAIRMAN ZECH:
All right.
Thank you very much.
21 DR.
SHERON:
The next slide, please.
(Slide) 22 The program is divided into a near-term and a longer-term 23 effort, and I'll get into that in a little bit here.
24 Could I have the next slide.
(Slide)
The major 25 areas that we're emphasizing in the near-term are those (202)234-4433 NEAL R.
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that are related to the early containment failure.
I-2 Basically, these are the scenarios that have the greatest t.
3 risk significance.
Since, obviously, anything that fails 4
the containment early. you have substantial release before 5
any settling or decay can occur, of the radioactive 6
fission products.
7 The issues that we're focusing on, I'm sure 8
you' e aware of, are the direct containment heating issue 9
for the FWRs, and the MARK I liner melt-through issue for 10 the MARK I BWRs.
11 We're also looking at an area that has been sort 12 of snoldering, I would say, in the back of people's minds, 13 and that is that if a severe accident were occurring at a 14 plant and if, for example, it was caused by a lack of 15 ability to add water to the primary system, and you 16 restored that capability,
- say, by restoring electric 17
- power, an operator would naturally opt to put as much 18 water as they could on the core, as fast as they could.
I 19 Depending upon the location of the core and, 20 during the course of the accident, whether it's in the 21 lower cavity or still in the vessel, their putting water 22 on a very, very hot molten substance can produce such 23 t h i rig s as steam explosions -- very, very large steam 24 generation -- and there's always been a question as to i
I 25 what are the effects of this, and one of the things we
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1-wantEto do'is,1 to help quantify'those effects not so much
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from'the standpoint 'of saying, gee. we would never tell an E
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If they saw a lot of steam generation, a lot of
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occu r ring l -- okay and if there is anything, any 10 precautionary measures they should take in advance.
So, 1,
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,this-is.something we're going to be studying.
It's more
' 12 or less'in the area of accident management, as well, r
13 There are two other areas that we're going to be m
14 focusing-on, and these are related to how we carry out the a~ ;-
15 research program.
This is the issue of scaling, or u
.c 16 similitude, and the issue 'here, which Dr. Costanzi will 17 talk'about a little bit more, basically, is that, as you 18 know from'when we studied ECCS, one of the questions we 19 always had was scale, and we started out with small scale 20 facilities and worked our wsy up to a large scale, like t
- 21 the LOFT facility and then almost a full scale with the 22 UPTF facility in Germany.
. 23 In ' severe accidents, which is a much more 24 complex. type of an accident to understand, most of our
~25 experiments, with the exception of very few, are small V
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.the scaling of that.
And, so, we're going to be taking a s
4 v e r y.' s y s t e m a t i c and ~ deliberate approach in lookingL at 5'
- that, to ' make. sure that we are able to scale or, more 6
importantly, understand when we are not able to scale.
"I The last. item we're going to be looking at also 8
i s ' ' a ccur a cy. criteria for our computer codes.
When we f
9 start z developing these codes, it's almost f rom scratch.
- LO Ws. are trying-to understand the basic phenomena, and I g
11 think w'e've been very successful in that.
12 The. computer codes, right now, are starting to 13 mature.
They're certainly not-at a stage where we would
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14
'want.to say we're say where we are now with the ECCS 15-codes, but.I think we've reached'a point where we want to
'16
'take when we.now. develop our codes further, we want to 17
. understand j a little better what the. uncertainties are, 18 what the benefits are of further improvements and, really,
'19 question of how accurate do these codes have to be in 20-order to' reach the conclusions that the Commission needs 21 to reach.
. So, we're going to be taking a hard look at the A
22 further development of codes, with regard to how much more
.23
. accurate that they need to be.
L 24 Next slide, please.
(Slide)
This is just a i
- f.,
.25 little more detail of these major areas.
As I said, in L
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addition to restructuring the programs into a near-and a 1
1 2
longer-term, we're revising the approach, and we've talked 1
3 to you about the scaling issue.
4 The rhird bullet there is the -- talks about the 1
5 increased emphasis on understanding late phase core melt 6
behavior.
The objectives here 'are to understand much
'l 7
better, the expected amount, composition and temperature 8
of the corium, the molten core, that would be available 9
for release from the lower head of a light water reactor.
10 For both the direct containment heating and the
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l 11 MARE I issue, the loads on the containment are very much 12 impacted by how the core is released from the vessel -- if 13 it's released very fast, if it's released in a slow 14 stream, what the driving pressure is, what the super heat 1
i 15 of that material _is, and what it's composition is.
Right 16
_now that's a very big uncertainty in the analysis, and we 17 are looking to develop experiments that will help better I
18 quantify what that is, so we can reduce those on the J
19 uncertainties, f
20 COMMISSIONER ROBERTS:
Have you seen anything
^
21 from the Three Mile Island incident that would help in 22 this?
23 DR.
SHERON:
We have a program underway right j
l 24 now, as you're aware, to take samples of the lower head, 25 which we feel is a major element of this part of the (202)234-4433 NEAL R.
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program, which is the next bullet, which'is understanding i
2 the modes of lower head failure.
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3 Right now.
the analysis that we would do would 4
indicate that if that amount of molten material were on j
5 the lower head.
it would have failed, yet THI did not 6
fail.
- And, so, one of the things we want to try and
~7 understand from this examination of the lower head, is why 8
it didn't fail.
9 As you know, there are competing effects.
10 There's heat transfer from the molten material to the 11 lower head, as well up,
- through, across, and into an 12 overlying pool of water, and relative heat transfer rates 13 and the like determine the temperature of the lower head-i 14 and how it would structurally fail.
15 CHAIRMAN ZECH:
But the investigation of Three 16 Mile Island. it seems to me, really, you should certainly 17 incorporate that in your research work, and try very hard 18 to learn what we can from that --
19 DR. SHERON:
Yes.
20 CHAIRMAN ZECH:
-- and integrate it into the 21 research that you're doing, as far as the lower head is 22 concerned.
I presume you intend to do that?
23 MR. BECKJORD:
Yes.
24 DR. SHERON:
Yes, that is a major element of the L
25 lower head examination program.
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CHAIRMAN ZECH:
Okay.
Thank you.
7--
L-2 DR.
SHERON:
And the last bullet is -- (slide) our anticipation is that if we are successful in 3
4 carrying out the above research, that we will'be able to
,5 reduce the current phenomenological uncertainties that are 6
associated with early containment failure.
7 Next slide, please.
(Slide)
I talked a little 1
I mentioned the approach we were going to take on 8
bit 9
further development of the computer codes that predict l
10 severe accident response.
11 What we're going to be doing is putting these on 12 a more structured schedule for development.
This would be 13 consistent with the current approach we've taken for the 14 thermal hydraulic codes.
And what this is is that we want 15 to make sure that the codes are all documented thoroughly, 16 at the time that they are released for general use.
I 17 Right now, typically, the -- in many cases, the i
18 development precedes the documentation by several months 19 to maybe a year or two, and this can be difficult when one 20 is trying to understand exactly what is in the code--
21 what the equations are, what is being solved, what needs 22 improvement, what doesn't.
}
23 Likewise, the need for the improvements in the i
i 24 code will proceed on a more structured basis, namely, that
)
25 before improvements are just made, we will be looking for (202)234-4433 NEAL R.
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justification from the code developers as to why these are 2
needed.
In other words, what is their importance?
What
(
3 is this improvement going to buy us in terms of increased 4
accuracy, better understanding of the performance, and the 5
importance to risk.
l 6
The fourth bullet, in the development of the 7
research program to-date, there's been a development of S
four core melt progression codes -- the MELPROG-TRAC code, 9
the RELAP-SCDAP code, the BWRSAR code, and the MELCOR 10 code.
We think it's appropriate at this time now that we 11 ensess the need to continue development of four codes, 12 that there may be some duplication of effort.
13 So, we'll be doing an assessment, probably 14 starting in FY90, to determine which codes we should 15 further develop and which ones we can terminate 16 development on.
17 And as I said before, the last bullet here is 18 that we're going to attempt to identify the code accuracy 19 criteria for that development.
The objective here would 20 be to improve our ability to clearly determine when a code 21 is sufficient, and that development can be stopped.
22 on the next slide -- (slide) -- I'm going to ask 23 Frank Costanzi now, to talk to you in a little more detail
{
24 about the near-term and longer-term goals.
25 CHAIRMAN ZECH:
Thank you very much.
You may i
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proceed.
2 DR. COSTAliZI :
Mr. Chairman, Commissioners, t
3 As we mentioned -- Dr. Sheron mentioned earlier, 4
the. revised severe accident research program has both a 5
near-term portion and a long-term.
I'm going to speak 6
first to the goals which we are going to attempt to 7
achieve in the near-term, near-term being the next three 8
years.
9 Specifically, the near-term goals are two:
- One, 10 to provide technological base for assessing containment 11 performance over the range of risk-significant core melt 12 events; and, secondly, develop the capability to evaluate 13 the efficacy o f-generic containment performance 14 improvements.
15 In reaching these goals, we're going to be 16 focused on five issues:
First, being an issue of scaling, 17 or similitude; direct containment heating; MARK I liner 18 melt through; the effect of adding water to a degraded l
19 core; and the accuracy criteria for codes and code 1
20 development, as Dr. Sheron mentioned earlier.
{
l 21 Next slide, please.
(Slide) l 22 CHAIRMAN ZECH:
The next slide.
1 i
i 23 DR. COSTANZI:
Yes, next one after that.
l 24 Next slide, please.
(Slide)
The first issue is l
25 the question of similitude and scaling.
What we're trying j
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to address here is the question of how to extrapolate from 1
I L -
2 small wcale experiments to full scale nuclear power plant i
3 accidents.
4 As Dr. Sheron rentioned, the research that we're j
5
- doing, the bulk of the experiments are lab scale l
l 6
experiments.
We're also using simulant materials, since i
l' l
7 trying to conduct an experiment with actual core materials 8
is very difficult as well as very expensive.
l 9
So, the questions we're trying to investigate 10 here are with regard to this, to make sure that we can 11 extrapolate with confidence from these laboratory scale 12 experiments to the reactor accidents.
So, we ask the 13 questions, are the correct phenomena being inv(. igated?
14 Are distortions of scale important to the process under 15 investigation?
For example, on distortion of scale, are 16 ship models of the towing tank, the scale model of the 17 ship is constructed and dragged through the towing tank, 18 to look at wave propagation and the like, but things like i
a 19 viscosity of the water and the wave velocity in the water 20 are not things which are directly scalable to a full-size l
i 21 ship, so there's a distortion there that needs to be
]
22 accounted for.
t 23 And that leads to the third question are 24 distortions characterized, understood and accounted for
^
25 when using these large codes, which are ultimately the I
J (202)234-4433 NEAL R.
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embodiment of our understanding of severe accidents.
2 To addrass this, we've designed a program to 3
develop a generalized approach to scaling severe accident 4
phenomena.
5 tiext slide, please.
-(Slide)
The second issue 6
we're addressing is depressurization and direct i
7 containment heating.
We're tracking this problem from a 8
rwo prong approach.
First, we're looking at the question 9
of depressurization as a mechanism to avoid DCH.
The 10 theory is that if you depressurize the primary system 11 early enough in the accident when the vessel fails, there 12 will not be any energy to forcibly eject the debris from 13 the vessel, and you will not fail the containment.
14 The second part of our research here focuses on 15 whether or not there may be down-sides of 16 depressurization, and to weigh those against what the 17 threat of direct containment heating might be.
18 Next slide, please.
(Slide)
In looking at 19 depressurization as a means to avoid direct containment 20 heating, questions that we're asking is, what is the 21 likelihood that the reactor coolant system will fail by 22 natural circulation prior to significant core damage?
You 23 know, high pressure sequence as the effluent boils off the 24 core, the hot gases could sort of circulate through the 25 primary system, could fail either a surge line or a steam (202)234-4433 NEAL R.
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21 1
1 tube, which would lead to depressurization.
-I t.
2 Next question we're asking,. is there a low-3 pressure cut-off below which there is no DCH. threat?
That 4
is to say if,-by whatever mechanism, the reactor coolant 5
system depressurized to a point where the amount of 6
material ejected into the containment upon vessel failure 7
would not be sufficient to fail the containment.
8 And the third related question is, if, indeed, a 9
low-pressure cut-off exists, is this pressure going to be 10 reached either by natural circulation-induced failure of 11 the RCS, or through operator action, or both?
l l
12 Next slide, please.
(Slide)
In looking at the 13 effects of depressurization, we're asking the question, if 14 operator action is needed to depressurize to avoid DCH, is 15 the operator going to have sufficient time to take that 16 action?
And what are the hardware procedural requirements 17 needed to make intentional depressurization successful?
18 Secondly, are there adverse consequences to 19 depressurization?
Is something untoward going to happen 20 if the operator proceeds to do this?
Or, if natural 21 circulation induces failure of the RCS, what is the risk 22 significance of that?
23 A third question is, what is the nature of the 24 DCH threat to begin with, and what mechanisms may exist
' ~
25 ex-vessel to mitigate the threat of DCH?
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Next slide, please.
(Slide)
The third issue 2
which we ' re _ going to address is BWR MARK I containment 3
shell meit-through.
Specific questions which we're going 4
to addrass in our research is, what are the relationship 5
of the BWR bottom head failure mode to variations in the 6
quantity, composition, temperature, and timing of arrival 7
of the melt on the bottom head?
8 Perhaps one of the major uncertainties we have 9
in understanding severe accidents are the details of the 10 core melt, and that seems, to our present understanding, 11 to be very significant to understanding what happens both 12 in terms of the way the vessel fails and, given the vessel 13 failure, of the way the melt comes down from the vessel 14 and what happens with the melt interacting with the 15 containment.
16 What we're asking here is, well, how sensitive 17 is the bottom head failure to the details of core melt 18 progression?
And this may be particularly important in 19 BWRs since there is a tremendous amount of thermal 20 mechanical inertia in the bottom head of a BWR, which may 21 make it less sensitive to the details of core melt 22 progression.
That's one of the questions which we're 23 going to investigate.
24 What is the effect of water on the drywell floor 25 when the melt pours out from the pressure vessel?
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= _ _ _ - _ _
4 i
23 1
Obviously, water is a coolant, and it's going to have some i
u.
2 effect on, and perhaps even cooling, the debris as it i.
3 comes out.
Certainly, water will tend to retain any 4
fission products that are being involved from the 5
interaction of the debris with the concrete, The question 6
is, how much can we quantify that?
7 Third, how does the answer to the above question 8
depend on the initial conditions?
Again, this is the melt 9
ejection rate, the composition, the temperature of the 10 melt coming down.
11 And the final question under BWR MARK I.is,
l'2 under what conditions would the crust that forms the i
13 initial contact between the melt and the shell freeze?
L..-
14 How long would it be stable?
What conditions would make 15 it stable, hence, going from an early containment failure 16 to perhaps a recovered accident or late containment i
)
17
- failure, which would certainly have far fewer 18 consequences, 19 Next slide, please.
(Slide)
The fourth issue 20 which we're addressing is adding water to - 4egraded core.
21 I want to say beginning here that we're assuming in this 22 research, that if the operator has the opportunity in the 23 course of an accident, to add water, the operator is going 24 to add water.
That's our initial assumption.
25 What we're not trying to do in this part of the (202)234-4433 NEAL R.
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l 24 r
1
- program, is address the question of when should-the 2
operator add water, or how much water, at what rate.
What 3
we're trying to do here is simply understand that if the 4
operator gets the opportunity to add water and does so, 5
what is the operator likely to see?
How is the plant 6
likely to respond?
Basic questions there -- how much 7
energy is going to be transformed into hydrogen, or how 8
much into steam?
9 Also, there is the question with BWR in-vessel, 10 if the operator adds water, the potential for criticality, 11 and what are the consequences of it?
next slide, please -- (slide) 12 The last issue 13
-- goes back to the question of codes.
As Dr.
Sheron 14 mentioned earlier, we're focusing very heavily on our code 15 program right now because that is the embodiment of our 16 knowledge.
When you understand something about severe 17 accidents, we put it in the code, so we can manipulate, we 18 can do calculations, and look at consequences.
19 The questions we're asking here is, how well do 20 the mechanistic models reflect the phenomena believed to 21 be important in severe accidents?
This is kind of a 22 question which you always ask yourself, am I modeling the 23 right phenomena?
Am I doing the right physics?
How well 24 does the interactive program of code advancement and 25 experimentation achieve the objective applied in (1)
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above?
We mean here the general way. we' proceed' _in
]
2 developing a code is, you take what physics you think is 3
important in the accident, you put it into a code.
You 4
use the code to help you _ design an experiment to test 5
that.
You run the experiment.
You go back and it helps 6
you improve the
- code, and it's iterative process 7
continues.
8 Now, the second question, you have to make sure 9
that you a'1 ways are going back to the accident, that 10 you're not just going off on a tangent, that the phenomena 31 and the experiments that you do all relate to the accident 12 you're worried about.
That's very closely coupled with 13 the question of similitude, the first issue that we're u_
14 examining.
15
- Third, is the level of detail in the codes 16 appropriate to their use?
We want to make sure that we're 17 not going off and developing very highly detailed codes to 18 answer questions which we don't really -- where the 19 significance or the sensitivity to impacts is not as great 1
20 as the detail.
We want to make sure that we're not i
l 21 putting more money into trying to understand phenomena in 22 minute detail, which we really don't need to understand 23 because it doesn't affect risk that much, i
24 Which stages of an accident need to be modeled i
I 25
- by detailed mechanistic codes, and which need coupling to
+-
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l' j
3 1
26
-1 adjacent stages?
This is a two-part question.
One,'as I 1
i 2
mentioned earlier, we have great uncertainty about the I
3 details of core melt progression.
That's-still our major 4
uncertainty.
5 The question is, do we need to resolve that 6
uncertainty in the kind of detail that we seem to think i
7 right now.
- de're going to examine that so that we don't' l
1 8
spend a lot of resources in understanding the fine details 9
of core melt progression, but find out that the 10 consequence of the accident is really not as sensitive-to l
11 the details as we might have originally thought.
i l
12
'd the question of coupling, is there feedback j
13 in the coarse of an accident, between one stage to j
14 another, that requires that you couple modules together so i
i 15 that when you're doing a calculation, that you have this l
16 feedback process going on so you don't over-estimate or 17 under-estimate by a significant amount because you forgot 18 this coupling when you do calculations.
19 tiex t slide, please, (Slide)
Is the level of 20 precision needed for regulatory use being considered?
21 This relates to the question of uncertainties, but also i
22 relates to the question here of, what are we going to do 23 with this code?
24 Right now, we have a program of what we call a 25 two-tier code program where we have very detailed (202)234-4433 UEAL R. GROSS & COMPANY, INC. (202)232-6600 1323 RHODE ISLAND AVENUE, N.W.,
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7-1 mechanistic codes which help us do the understanding of-I
'2 experiments and understanding of the details of sequences L -
3
.i n an accident, but when we do analyze plants or, 4
presumably, we will begin analyzing accident management 5
strategies, we're not going to use that level of detail.
6 We're going to use codes which are much simpler.
7 They give broader-brush sorts of answers, still valid, but 8
not with the same degree of precision.
You don't need 9
them.
We want to make sure that the codes that we develop 10 for those kinds of purposes,
- again, have a level of 11 precision which matches what the regulatory need is.
12 And that relates to the last question which is, 13 is the level of precision needed from a given code 14 consistent with the expected overall level of accuracy 15 required in the integrated analysis package for 16 applications.
Accident management is probably the primary 17 one.
13 Okay.
The next slide, please.
(Slide)
The 19 long-term goals of this program -- I might mention at this 20 point, before I forget, so that it is very clear -- we are 21 not going to proceed with the program over the next three 22 years, which is the near-term program -- finish that, and 23 then pick up a long-term program.
l 24 The near-term program is being drawn out of the i
25 continuing research which we are doing in severe accident j
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28 t*
I area.
I t'.' s a focusing.
It's not. switching from one i.
2 program to another.
So.
when lI talk about- 'long-term.
L ll 3
-goals, these.are still things which we are studying right 7
4 now.
They are not things which we're going.to wait three lt 5
years'before we start looking'at them, l
i L
6 Our goals'for the-long-term is to' provide better 7
understanding of the range of phenomena in severe f
8 accidents.
This is essentially so that we can understand 9
the-utility and benefits of accident management
-10
- s t r a t e gi e s ~.
I think that's our primary use of this, 11 although there are others.
12
- And, secondly, relates to the source t e r m,-
~
13 develop improved methods for assessing fission product 14 behavior and the. availability of fission products for 15 release in a severe accident.
16 Next slide, please.
(Slide)
In achieving these 17 long-term goals, we're going to have our research directed 18 at, one, reducing the uncertainties in the estimate of 19 risk, but also raaking sure that we have a broadly based 20 severe accident research program, so that we can respond l
21 to changing technical priorities as they may arise over j
22 the next three years, and we've tried to lay out a program l
g 23 in which we think we're going to hit on what's important 3
24 in the near-term and address those, but, you know, we're j
25
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that our program is sufficient broad and robust that we I.
2 can respond to changing technical priorities.
i 3
What we are going to be addressing are-seven 4
areas of modeling the severe accident phenomena, is the 5
first -- we just want to make sure we're pursuing the most 6
risk-significant phenomena first.
7.
In-vessel core melt progression and hydrogen 8
generation.
This is, again, the question of details of i
9 core melt progression and what happens there.
I 10 Hydrogen transport and combustion.
Here, we're 11 going to be focusing on, primarily, on high-temperature 12 hydrogen, high-steam environments within the containment.
13 Fuel coolant interaction and molten core s _J 14 concrete interactions is primarily for accident management 15 purposes.
16 Fission product chemistry and transport source 1
17 term question came up again.
i 18 And the last thing is the fundamental data J
19 needs.
Here, we're looking at both materials properties 20 since, ultimately, it's how the materials respond that 21 determine what happens in the course of an accident, and 22 also the experimental data base, what data is available or 23 needed for validation of these severe accident codes 24 which, as I say, is our embodiment of our understanding.
l 25 With that, I will turn the presentation back to (202)234-4433 NEAL R.
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Dr. Sheron.
2 CHAIRMAN ZECH:
Thank you very much.
3 DR.
SHERON:
Next slide, please.
(Slide)
I 4
guess this is the important stuff, is the money.
Right 5
- now, what we've done is, we've done our resource 6
projections for carrying out this program' from FY90 7
through FY92.
8 What we are proposing is that we will carry this 9
out, this revision, consistent with the current five-year 10 plan approved by the Commission.
What that means is, i
11 we're not going to ask for anymore money.
12 What we will do to implement this is to fund it 13 by either
- reducing, or deferring, or perhaps even 14 canceling research that we think would be of lower it; consequence in terms of its results.
16 So, basically, it's -- we're just going to re-17 prioritize where we spend our money, where we think we'll 18 get our best results.
19 What you see there in this abbreviated table is i
20 the FTE that we will be expending on it -- that's the 21 branch FTE in Dr. Costanzi's branch -- and the contractor 22 assistance, which is the research money that the j
23 laboratories would and that the contractors, 24 universities and the like, for carrying these out, and 25 these are the numbers that are in the five-year plan, j
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COMMISSIONER ROBERTS:
But the bulk of that is l~
i_
-to the national labs?
2 3
DR.
SHEROM:
- Yes, I don't -- do you know what 4
the split is right now?
5 DR.
COSTANZI:
I don't know, but I think the 6
bulk is certainly --
7 DR.
SHERON:
The bulk is primarily because of 8
the large experimental costs.
9 Next slide, please.
(Slide)
This just shows a 10 breakdown of the -- what we would be spending from FY90 11 through FY92, to carry out the near-term issues 1 through 12 5.
These are the scaling, the depressurization and DCH 13 research, the MARK I, and the add water to degraded cores, 14 and also the computer codes, and that's about $14.6 15 million.
16 On the next --
17 COMMISSIONER ROGERS:
Excuse me.
18 DR. SHERON:
Yes, sir?
19 COMMISSIONER ROGERS:
Is that a three-year or a 20 four-year period?
21 DR.
COSTANZI:
It's three years,
'90 through 22
'92.
23 DR. SHERON:
It's three years, '90 through
'92.
24 COMMISSIONER ROGERS:
It says
'93.
i 25 DR. SHERON:
I'm sorry, there's a typo there on (202)234-4433 NEAL R.
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the first bullet.
I thought that had been corrected on i
l-2 your c,opies.
That should'be a "2".
j l
3 COMMISSIONER ROGERS:
Okay.
S o,. this is a I
4 three year program then?
5 DR. SHERON:
Three-year, yes.
6 DR. COSTANZI:
The same thing on the next page.
l 7
DR. SHERON:
Okay.
Also, on the first bullet on 8
the next page, page 23, that also should be
'92.
9 COMMISSIONER ROGERS:
Okay.
I 10 DR. SHERON:
Okay.
These are the resources for I
11 the longer-term issues, again, for the three-year period, i
12 and these numbers, again, if you add the two, they are 13 consistent with the five-year plan.
14 And beyond 1992, the -- any further research 15
- needs, the budget would be -- come, you know, f"om the 16 normal Commission approval process for the budget.
17 COMMISSIONER ROGERS:
Do you have handy there, 18 the breakdown, year-by-year, of near-term and long-term 19 expenditures?
In other words, on page 21, slide 21, what 20 the breakdown is for the $18 million and each succeeding 21 year, in near-term and long-term?
22 DR. SHERON:
Is that anywhere --
23 DR. COSTANZI:
I think it was in a Commission 24 paper.
It's roughly level.
It's roughly level.
25 COMMISSIONER ROGERS:
Roughly level for each of (202)234-4433 NEAL R.
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1 them?
Okay.
J 2
DR. SHERON:
And the last slide. 24 -- (slide)
,L 3
-- just to conclude, that is that we are starting to 4
implement this program now.
There are some programs which 5
we are starting to revise right now, in FY89, to implement l
6 this program.
We
- think, though, that the full 7
implementation will begin in FY90.
8 One of the things we're doing right now is 9
starting to develop our statements of work to be sent out 10 to the contractors, from which we would expect proposals 11 to come back in.
These statements of work will reflect 12 the emphasis on the short-term and consistent with this 13 overall revised approach.
t __
14 As you know, we met with the ACRS on a number of 15 occasions, in developing this plan.
You've received a l
l 16 letter from them.
We are going to continue meeting with j
l 17 both the Subcommittee on Severe Accidents as well as the 18 full committee, as we go forth and put this in place.
)
19 We are -- hopefully, we will get strong support 20 from across-the-board, to assure that we can put this i
21 program in place.
Obviously, it's a major change in some i
22 corners, and so, obviously, there may be people that are 23 h e s i t a r. t to either embrace it or the like.
So, we're l
l 24 hoping that we will get strong support across-the-board on l
l 25
- this, and we would propose to come back and brief you (202)234-4433 NEAL R.
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periodically, on our progress in putting this plan in 2
place.,
And that concludes my presentation.
.3 CHAIRMAN ZECH:
All right.
Thank you very much.
4 MR. STELLO:
That's all we have, Mr. Chairman.
i 5
CHAIRMAN ZECH:
All right.
Thank you.
6 Questions from my fellow Commissioners?
7 Commissioner Roberts?
8 COMMISSIONER ROBERTS:
I have no questions, just l
9
-a comment.
-This is a terribly important program and, as 10 you well know, the agency certainly had its critics of its
{
11 research program.
I'm delighted you got the ACRS onboard, 12 and I hope that continues.
That's all I have.
13 CHAIRMAN ZECH:
Thank you.
Commissioner Rogers?
14 COMMISSIONER ROGERS:
Yes, I've got a couple of 15 questions.
Just coming back to this budget question, to i
16 what extent have you prioritized your budget in such a way 1
1 1
17 as to be able to use the research results for -- in 1992, 18 when the IPEs and PRAs come in, or have to be dealt with, l
19 f rom an NRC decisioninaking point of view?
20 Will the work be done during the first three 21 years in such a way that you have the most useful results 22 in hand for those purposes, and have your budget 23 priorities been set to do that?
l 24 DR.
SHERON:
Yes.
By its very nature, the 25 short-term issues are high priority issues.
If you l
l l
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remember, the IPE generic letter essentially has told the r.
I 2
industry that in conducting.their IPEs, that they did not, L.
3 at that time, have to address these specific issues that 4
we're looking at here, the DCH or the melt through, the 5
liner melt throuch.
6 The approach right now is to try and maxinize 7
this information that will be available for the industry 8
at the time when they will be making their submittals.and 9
the like.
10 In terms of the actual budget money, what we're 11 looking at is, what research do we need to do?
Another 12 question is, how much does that cost?
It may not be a 13 matter of if I put more money I'll get more information.
14 We're putting -- sort of optimizing the amount of money 15 that will get us the maximum benefit for -- within the 16 next three years.
17 COMMISSIONER ROGERS:
Well, have you had to 18 define or put any research in the long-term category, just i
19 simply because you're trying to tuck it into the five-year j
20 plan expenditures?
Has that driven a definition of long-a i
21 term versus near-term to any extent?
22 DR.
COSTANZI:
No, I don't think so.
What 23 determined what was near-term and what was long-term was 24 primarily 88-147, the closure plan -- severe accident i
25 closure plan, and what we thought we could achieve in (202)234-4433 NEAL R.
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three years.
j 2
We took a hard look at where we were in i
f 3
understanding severe accidents, and what we thought was 4
achievable in three years or, as I said, a good shot at 5
it, and what we just recognize is going to have to be 6
either a long-term goal or part of a -- you know, 7
consistent part of an ongoing program.
Materials property 8
is an example of one of -- it's just something you 9
continue to do, but that was basically how it was broken 10 down, and we added up the money accordingly.
11 DR.
SHERON:
Yes.
If you recall, I think back 12 on slide 5, as I said, one of the things we really used in 13 helping us do this was 1150.
We wanted to see what was 14 that telling us about where we should put our resources.
15 COMMISSIONER ROGERS:
Well, I guess the thing 16 that puzzles me a little bit, just in that you're spending i
17
-- you're projecting to spend about three times as much l
18 each year for long-term projects, as for near-term 19 projects, during the first three-year period, and I don't 20 know whether you expect to finish the near-term projects 21 within the three-year period, or whether they extend out 22 beyond that -- certainly, the long-term ones will -- and 23 how that relates,
- again, to the usefulness of these 24 research results for 1992, when you're going to start to 25 need them.
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DR.
SHERON:
The best way I can answer that is
.I 2
that this is our best guess at this time. Obviously, as we t.
l.
3 get further into defining this program, there may need to 4
be some adjustments made,
- but, you know, obviously, if 4
5 somebody walks in and says, "I
can give you an experiment 6
for 'X-amount of dollars that will definitively solve direct containment heating", and maybe it's going to cost
~
8 more than what we've put here, obviously, we would 9
consider that, but the objective here is to try and to 10 reach some sort of a conclusion on these major issues 11 within about three years, rather than leaving them 12 hanging.
13 COMMISSIONER ROGERS:
But do you really expect 14 the near-term issues to be resolved by 1992?
Is that --
15 DR. SHERON:
That's our objective, yes.
16 COMMISSIONER ROGERS:
That is.
17 DR. COSTANZI:
Yes.
18 COMMISSIONER ROGERS:
You don't explicitly say 19 that.
You say that you have these near-term objectives 20 and you have a budget, a near-term budget, but they are 21 not necessarily -- they don't necessarily terminate at the 22 same point in time.
23 DR. COSTANZI:
On the near-term portion of the 24 program, we have very specific questions which we're going 25 to try and answer, and the figures, the budget figures for (202)234-4433 NEAL R.
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'i 38 4-1 the near-term, are related to the programs to answer those 2
specific questions.
3 Now. those questions aren't going to be answered 4
in a vacuum.
The ongoing research which we call the long-5
- term, is going to help support the answers to those 6
questions, but the specific programs which are aimed at 7
developing the answers to those specific questions, are 8
what appears in the budget figures for the near-term.
9 COMMISSIONER ROGERS:
Well, just the point that 10 you expect that these five topics to be more or less dealt 11 with at the end of 1992.
12 DR. COSTANZI:
Yes.
13 COMMISSIONER ROGERS:
All right.
14 MR. ROSS:
Commissioner Rogers?
15 COMMISSIONER ROGERS:
Yes?
16 MR. ROSS:
There's a variation on this that I 17 think the Commission should know about.
The utilities 18 sponsored research -- for example, Commonwealth Edison is 19 doing its own plant-specific direct containment heating 20 research.
They're doing cavity designs of their own 21 reactors, and doing ejection of simulants and measuring 22 dispersal, in furtherance of IPE, and the BWR owners 23 groups are doing their own liner melt-through research.
24 So, it well may be -- we'll have to wait and see 25 what the results are, but the definitive solution for IPE, (202)234-4433 NEAL R. GROSS & COMPANY, INC. (202)232-6600 1323 RHODE ISLAND AVENUE, N.W.,
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'l 39 I
to the extent research is needed, may be that that's 2
tendered by the industry.
L 3
COMMISSIONER CURTISS:
I guess the more on 4
the schedule topic, the more immediate schedule or 5
question that I have is related to the CPI program where.
6 we've got the MARK I fixes now before us, and the 7
remaining fixes are r*ue in about eight months from now.
8 T gather that a large part of the focus of this 9
program, particularly in the direct containment heating 10 and the hydrogen area, will go to containment performance 11 and containment integrity.
With the near-term program 12 running three years I gather we're kind of into it 13 right now, but will be geared up in FY90 through
'92, I
1 14 guess the question that I have is, will this research be 15 available prior to or incorporated in the CPI fixes, or is 16 it envisioned that the research here in the short-term 17 area for CPI, is going to be confirmatory?
Can you talk 18 about that?
19 DR. SHERON:
For the MARK I, I believe it would 20 be confirmatory.
The MARK I improvements 21 COMMISSIONER CURTISS:
I understand that.
were basically balanced between 22 DR. SHERON:
23 a prevention accident management and a mitigative 24 approach.
I i
25 COMMISSIONER CURTISS:
I guess I'm focusing on (202)234-4433 NEAL R.
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the other fixes that come in in January of '90 -- the ice 2
condensers and the large drys and the sub-atmospherics, 3
where it looks, if that schedule holds, like we'll be 4
getting recommendation's on the CPI fixes more than two 5
years before the conclusion of the near-term research 6
program.
Can you talk'about that a little bit?
7 DR.
SHERON:
Yes.
Right now, I guess, in 8
talking with the people who are working on CPI, it's not 9
clear yet how they intend to proceed.
In other words, I 10 think if they feel that this program will produce 11 information that would provide a more definitive 12 conclusion on the vulnerability, say, of a large dry to 13 DCH -- for example, they may defer addressing specifically 14 the DCH issue until that information becomes available, 15 and maybe they would just focus in on perhaps the hydrogen 16 aspect of it, of the large drys.
17 I don't think it's clear yet because it's not 18 really clear what the fix is, I guess, for the large drys 19 either, for DCH.
20 COMMISSIONER CURTISS:
I guess my point is, you 21 don't know what -- it won't be clear what the fixes are 22 until you get the research done, will it, or is that not 23 correct?
1 24 DR. SHERON:
There may be improvements that can j
l 25 be made, that would not hinge on the research results.
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COMMISSIONER CURTISS:
I'm sorry.
Go ahead.
I 2
COMMISSIONER ROGERS:
No, that's fine.
Just how L.
3 are you incorporating plant operating and systems 4
engineering expertise in your program?
How do you 5
actually incorporate kind of hands-on experience rather 6
than the research laboratory experience, into the research 7
program?
8 DR.
SHERON:
This would primarily come through 9
the accident management in other words, the interface 10 of the operator with the system.
That is primarily being 11 accomplished through the accident management program, and 12 you had a briefing on that, I guess it was in January.
13 One of the things we are doing in that program i
14 right now is looking to contract with either organizations 15 or individuals as consultants, that have actual hands-on 16 operating experience.
That was one of the comments we had 17 received from Dr. Todreas', you know, group.
So, that's 18 where that impact would come from.
19 We also have a lot of human factor work going on 20 in conjunction with the accident management research, on 21 the human interface in accident management, but I'm not 22 aware of any right now that we have in conducting this 23 actual phenomenological type of research.
24 COMMISSIONER ROGERS:
Well, I think that's a 1
25 very important aspect of this, and I saw on your slide 14 (202)234-4433 NEAL R.
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that one of the questions on depressurization is -- you 2
- know, is there time available for operators to take 3
action.
Well, how do you decide that?
To what extent are a
nperators i nvol ved in arriving'at that kind -- in answer 5
to that kind of a question?
6 MR.
STELLO:
- Remember, Commissioner Rogers, 7
we've asked industry, and I understand they will put 8
together a group to help us do just this, through bringing 9
in people with that kind of expertise and dealing with the 10 severe accident management issues, to make sure they --
11 COMMISSIONER ROGERS:
But what would the 12 mechanism for that be between those two plans?
13 MR. STELLO:
Well, they're going to get a group 14 in to make sure that the coupling, on how you handle the 15 severe accident procedures, has that kind of thinking, 16 from the hands-on plant operator point of view, and making 17 sure that those are, in fact, reasonable procedures and 18 processes that we propose, and they have committed to put 19 together that group and help deal with that issue.
20 COMMISSIONER ROGERS:
Okay.
On your 21 experimental programs, thost laboratory experiments of 22 various kinds, I had a little difficulty identifying how 23 much experimental work there is and how much is computer 24 code development and theoretical work in the overall 25 program and, in connection with that, I wonder what your (202)234-4433 NEAL R.
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1 thinking is of the necessity for duplicative experiments i
2 to verify some of these results.
It's a tricky question i
t _
i 3
because, if you're talking about large scale experiments, 4
hnw many can you mount but how are you coming to--
i 5
arriving at that kind of a decision, when you've got a 6
large scale experiment that is unique?
What verification 7
experiments can you conduct, or are you thinking of being 8
able to -- what kind of data can you bring onto this to 9
verify that it's been correctly assessed?
10 DR.
C O S T A !! Z I :
- Well, you know, that's a 11 difficult question which we're constantly dealing with in 12 this program, but we do attack it from a number of 13 positions.
First, we do certainly duplicate on a selected i
L--
14 basis, the small scale experiments.
15 We tend to rely even more heavily on the 16 questions of scaling, and this is scaling methodology 17 which we're attempting to develop, to then extrapolate to 18 larger scales, and we'll do some larger scale experiments 19 and then, of course, ultimate extrapolation to the 20 accident.
21 We're also trying to coordinate our research 22 with EPRI-sponsored research, as well as research that is 1
23 taking place in other countries, both for large scale and 1
24 small scale experiments, so that there is some overlap, 25 that there are certain benchmarks provided in their (202)234.4433 IJEAL R.
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experimental program and our experimental programs, by-2 which we can compare and then, essentially,' leverage the 3
utility of several research programs, to try and come to 4
grips with the severe accident question.
5 So, it's a combination of doing some very--
6 some duplicative experiments at the lab' scale,
'7 occasionally, on a large scale, comparing and then 8
benchmarking our experiments with experiments by industry 9
as well as experiments and experimental programs in other 10 countries.
I 11 COMMISSIONER ROGERS:
- Well, it would be 12 interesting to know, when all is said and done, when 13 you've more or less finished, what pieces of important 14 data are essentially unique, that they're one of a kind, 15 that you haven't been able to do that, for just practical 16 reasons.
17 DR. COSTANZI:
One of the programs which we're 18 looking at right now is to try and assemble a catalog of 19 severe accident research experimental data, to try and put 20 it all together and find out just those kinds of questions 21
-- what data is available, what experiments have been 22 done, how good is it, what it can be used for, has it been-23 verified or matched by other experiments, or is it unique 24
-- and we have a contract under consideration right now, 25 to do just that.
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.1 DR.
SHERONi The scaling work, which - is being 2
headed up'by Dr. Zuber, is also designed to'do just.that.
o a C; l : L F.
3 It's to look at these experiments, and.he's -- right.now, 4
'he's.
focusing in, f or. example, on the SERTSI facility, 5
which is the one-tenth scale direct containment heating 6
facility out in Sandia, and that's' to primarily look at 7-
. whether there 's any unique aspects of that facility that-8 are either distorting it in terms of its scalability, and 1
~
'9
-- but that 's ' really one of the reasons we focused in on 10 that program, is-to address the' very question. you' re 11 asking.
12 COMMISSIONER ROGERS:
Does your scaling program 13 T;. assume it does -- deal with not only size scale, but 14 dimensional scale -- 2D, 3D questions?
15 DR. SHERON:
Yes.
16 COMMISSIOtIER ROGERS:
You do that.
17 DR. SHERON:
Yes.
18
. COMMISSIONER ROGERS:
All right.
Good.
Thank 19 you very much.
It looks like a good program.
20 CHAIRMAN ZECH:
Commissioner-Curtiss?
1 21 COMMISSIONER CURTISS:
I just have maybe an 22 observation and perhaps a coupit of requests.
- One, it 23 seems to me that the program's well thought out.
I,
- too, 24 am pleased that we've gotten a consensus with the ACRS and j
I i
25 the review committee and EPRI, and it looks to me like (202)234-4433 UEAL R.
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it's well thought out and a forward-looking program.
2 Just a couple of requests.
When you reach the 3
point when you identify those research programs that will 4
need.to be postponed or cancelled, if it would be possible 5
to let us know, maybe just in an information paper, what 6
those are, to get a sense of what the choices-are here, 7
first.
8 And then, secondly, maybe a question that goes 9
more to the. folks working on CPI.
I still, I guess, have 10 questions about the schedule or relationship between the 11 research results of this program and the CPI program, and l
12 perhaps if the folks who are working on the CPI can give 13 us some sense of what impact, if any, the research program 14 that you've laid out will have on their schedule for the
'15 remaining CPI fixes, I'd be interested in that.
16 DR. SHERON:
Okay.
17 COMMISSIONER CURTISS:
That's all I have.
Thank 18 you.
19 CHAIRMAN ZECH:
Thank you.
L 20 Well, let me just make a comment.
First of all, 21 I think this has been an excellent presentation, not only 22 with the information you've presented us, but I think 23 Research office, Mr. Beckjord, you and your people are to 24 be commended on the coordination that you're doing with 25 other activities.
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1 I 'think it's import ant that you do Phis.
The 2
fact that you've coordinated well with the ACRS, with, I I
p p
3 notice, too, in your paper, wi th AEOD and the tJRR, in our 4
own organization, as well as with EPRI and your IJuclear 5
Safety Research Review Committee, other industry groups, 6
ur. iv e r s i t ie s, too This is the kind of thing I think the
)
7 Commission has been wanting to see for a long time.
R We recognize that there's a lot of talent in our 9
Research people here, but I think that your efforts to 10 coordinate with others, and to listen to what they have 11 to say is extremely.important and it certainly broadens 12 our base and gives us a greater confidence that our 13 research program is doing what we want it to do.
I i
14 commend you for that, and I would ask you to continue in 15 that direction.
16 So, I think that, in itself, as much as the 17 details you've presented, is extremely important, and I 18 commend you and your people in Research, who are doing 19 that.
I think you recognize that the Commission has a 20 great deal of respect for what research can offer to our 21 regulatory decisions, but they must be integrated, and 22 they must be part of our program.
23 They can be.
We know they are, but your efforts 24 to go outside your own organization to make sure that your i
25 research is consistent with and supportive of our (202)234-4433 NEAL R.
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- y [',
h I',
regulatory decisions is. extremely important, and-I commend y'
'2
- you for that, again, 3
I think that the -- also, I'd like to just-q 4'
' mention that-the ACRS
~
read with. great interest the
.5 letter' -that they wrote to the ' Commission, and also the
~6 comment they had that said that regarding the proposed 7
severe' accident-research program plan,.the'ACRSEcommented
'8 that. they felt it represents ~ a substantial change from 9
previous severe accident research programs, and is a very 10 positive' step.
I commend'you f o r - th a t, t o.o,. because the 11 ACRS do have a lot to offer us in an advisory capacity, 12 and you briefed them, I notice, on 'several occasions, and
-13 not only the subcommittee but the full committ'ee.
I.think 14 that.is important, too, because. we do listen to their 15
- comments, and your ef f orts to be close to them is 16
. important to the Commission.
17-And the ACRS comment'that you have.a -
you made 18-a specific effort to ensure that your contractors show 19 that the proposed continuing work that they're doing 20 addresses the analysis and the important phenomena that 21
'are aimed at predicting risk, and were clearly defined
.22 objectives.
- And, so, the focus you've made on. that, as 23 pointed out by the ACRS, I think, is important also.
24 So, I think the plan certainly shows that you've 25 attempted to go beyond your own office and to interface s
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I 1-
-with : others who can, contribute :' to ourt effort in severe q
p
]
2 accident research.
' I.
j LA-3 I also nota that youve emphasized efforts to 4
eliminate duplication' of effort, and to prioritize your 5
.research program, and I'd'.just simply note that that's j
'l 6
good management.
f 1
7 We don't have unrestrained resources.
Research 8
is so important to our programs.
We simply must put.our 9
dollars where we can get the most impact on our regulatory 10 safety decisions,-and'I clearly commend you for that.
11 The Commission has stressed on many occasions, 12 the need to better integrate our research program with our 13 regulatory programs, and it would look to me, Mr. Stello, 14 Mr. Beckjord, that you're clearly doing that..
That's what p ; L.-
15 we want to see, and I think we're seeing it.
- And, so, 16 that's why it's particularly encouraging to me to hear 17 those views at this briefing.
18 I think, again, that-the Commission recognizes 19 that we'll be able to.nake better regulatory decisions 20 when we have solid research that's well integrated, not at
~21 the'last minute, but continually as you're moving through 22 these difficult analyses and tests and studies that 23 research contributes to so heavily.
And, again, it will 24 help us carry out our statutory responsibilities for i
25 public health and safety, if we recognize that the (202)234-4433 fiEAL R.
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's 1
research program is making such a strong contribution, and i
2 I only look ahead a little bit to the waste issues we have 3
in front.of us, as well as the severe accident issues, and 4
look to the plant life extension program where we are 5
going to count on strong research efforts.
6 So, in those areas,
- too, as well as severe 7
accident,- I would encourage you to continue the. ef f orts 8
you've obviously. made in this area, to go outside our 9
agency and to seek the advice and counsel of those in 10 universities and -- as well as your review committee, and
)
11 the ACRS, EPRI, and others, who can assist.
12 So, I'm very encouraged by what I've heard 13
- today, and I think that you're showing the proper i
14 direction in your severe accident research plan, and in 15 particular your strong efforts, obviously, to coordinate 16 and cooperate with others.
17 Do any of my fellow Commissioners have any other 18
-- yes?
19 COMMISSIONER ROGERS:
Just one more brief thing, 20 and that is that I was very favorably impressed with 21 everything I heard today, and I certainly learned a number 22 of things.
23 It seems to me that it wou'i be helpful, 24 perhaps, for you to emphasize in your whatever summaries 25 of this program that you write up, that what the rationale (202)234-4433 NEAL R.
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was for your division into near-term and long-tern work, 2
not what the division was but the rationale for that i
3 divisibn, so'it's clear what your philosophy is and your 4
point of view in making those decisions and assignments 5
because I think it will help you to give a greater sense 6
of integrity to the entire program.
7 CHAIRMAN ZECH:
Are there any other comments?
8 (No response.)
9 If not, thank you for an excellent presentation.
10 We stand adjourned.
11 (Whereupon, at 11:14 a.m.,
the meeting was 12 adjourned.)
13 14 u
15 16 17 18 19 20 21 22 23 24 25 (202)234-4433 NEAL R.
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{
f 1
1 CERTIFICATE OF TRANSCRIBER This is to certify that the attached events of a meeting of the United States Nuclear Regulatory. Commission entitled:
TITLE OF MEETING:
BRIEFING ON SEVERE ACCIDENT RESEARCH PLAN i
PLACE OF MEETING:
ROCKVILLE, MARYLAND
)
l DATE OF MEETING:
MAY 2, 1989 i
were transcribed by me. I further certify that said transcription i
is accurate and complete, to the best of my ability, and that the transcript is a true and accurate record of the foregoing events.
h Wok u
v v
Reporter's name:
PHYLLIS YOUNG J
e e
NEAL R. GROSS COURT Rep 0RTtt$ AND TRANSCRIBER $
1323 RHODE IS6AND AVINUE, N.W.
(202) W433 -
WASHINGTON, D.C.
20005 (202) 232-6600 i
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