ML20212A608
| ML20212A608 | |
| Person / Time | |
|---|---|
| Issue date: | 12/17/1986 |
| From: | NRC COMMISSION (OCM) |
| To: | |
| References | |
| REF-10CFR9.7 NUDOCS 8612240274 | |
| Download: ML20212A608 (91) | |
Text
'
M
~
~
ORIGINAL
[
UNITED STATES OF AMERICA NUCLEAR REGULATORY COMMISSION In the matter oft COMMISSION MEETING Briefing on Source
~
Term and Severe Accident Matters (Public Meeting)
Docket No.
[
s Location: Washington, D. C.
Date: Wednesday, December 17, 1986 Pages:
1 - 68 8612240274 861217 PDR 10CFR PT9.7 PDR ANN RILEY & ASSOCIATES i-----
Court Reporters 1625 I St., N.W.
l Suite 921 Washington, D.C.
20006 (202) 293-3950
t 1
1 4'
j 1
D 1 SCLA I MER 2
3 4
5 6
This is an unofficial transcript of a meeting of the 7
United States Nuclear Regulatory Commission held on a
12/17/86 In the Commission's office at 1717 H Street, 9
'ii. tJ., (Jash i ng t on,
D.C.
The meeting was open to public 10 attendance and observation.
This transcript has not been 11 reviewed, corrected, or edited, and it may contain
?
g 12 inaccuracies.
13 The transcript is intended solely for general 14 Informational purposes.
As provided by 10 CFR 9.103, it is 15 not part of the formal or informal record of decision of the 16 m.s t t ers discussed.
Expressions of opinion in this transcript 17 do not necessarily reflect final determination or beliefs.
No 18 pleading or other paper may be filed with the Commission in 19 any proceeding as the result of or addressed to any statement 20 or argument contained herein, except as the Commission may 21 authorl=e.
22 23 24 25
A
+
1 1
UNITED STATES OF AMERICA 2
NUCLEAR REGULATORY COMMISSION 3
4 Briefing on Source Term and Severe 5
Accident Matters 6
(Public Meeting]
7 8
1717 H Street, N.W.
i 9
Room 1130 i
f 10 Washington, D.C.
i 11 Wednesday, December 17, 1986 i
12 The Commission met in public session, pursuant to 13 notice, at 2:00 p.m.
14 COMMISSIONERS PRESENT:
)
15 Lando W.
Zech, Jr., Chairman a
16 James K. Asselstine, Commissioner 17 Frederick M. Bernthal, Commissioner 3
18 Thomas M. Roberts, Commissioner 19 Kenneth ;!. Carr, Commission 20 STAFF AND PRESENTEko SEATED AT TABLE:
21 V. Stallo, EDO D. Ross j
22 S.
Chilk, SECY I
23 S.
Crockett, OGC l
24 Z. Rosztoczy 1
25 T. Speis i
)
O 3 -
2 1
PROCEEDINGS 2
CHAIRMAN ZECH:
Good afternoon, ladies and 3
gentlemen.
4 This afternoon the Commission will be briefed on the 5
status of Staff efforts to implement the severe accident 6
policy statement.
The main activity under this implementation 7
program is an individual plant examination for severe accident 8
vulnerabilities.
9 It is my understanding that the Staff has developed 10 guidance criteria to be used in these assessments.
The Staff 11 will also bring the Commission up to date on activities 12 related to the introduction of more realistic source terms in 13 the licensing.
14 Also the Office of Research will inform the 15 Commission on the status of plans to resolve major areas of 16 source term uncertainty.
This is not a meeting requiring a 17 vote on the commission, but will be information type briefing.
18 It is my understanding that Themmy Speis and Zoltan l
19 Rosztoczy -- I hope that's right -- is that pretty close?
20
[ Laughter.)
21 CHAIRMAN ZECH:
Rosztoczy.
All right, fine.
I'll 22 try to do better next time.
-- and Denwood Ross of Research 23 will give the presentations.
24 Do any of my fellow Commissioners have opening 25 comments to make at this time?
i
4 3
1 COMMISSIONER ASSELSTINE:
No.
2-CHAIRMAN ZECH:
If not, I will turn the meeting over 3
to Mr. Stallo.
4 MR. STELLO:
I think you have given a pretty good 5
summary of what we intend to cover.
I wanted to just 6
emphasize one particular point, that we will come up -- that 7
did come up the last time we talked about this subject, and 8
that was dealing with a plan to get into the issue of how to 9
handle and deal or reduce uncertainties, and the need to 10 develop a group similar to what we had before in the steam 11 explosion question, and we will be discussing what we have put' 12 in place to deal with those issues.
Hopefully we will answer 13 the questions that are raised in this area.
14 We have pretty well described our activities in the 15 SECY paper 86-369, and we will basically review some of that 16 here today and extend beyond what's in there to a degree.
17 So without taking too much more time, Themmy, why 18 don't you get started.
l 19 MR. SPEIS:
Thank you.
Thank you, Mr. Chairman, 20 Commissioners.
21
, Mr. Chairman, you said that today I will provide the 22 Commission with a status report of the implementation program 23 for the Commission's action policy statement.
24 Even though the policy statement deals with both 25 future and existing plants, today we will focus on existing
9 Lo 4
1 plants and dwell more on future plants in the next commission 2
meeting.
3 My presentation is divided into three parts.
First 4
I will provide you with an overview of the severa accident and 5
source term implementation program.
6 Number two, I will discuss the program to examine 7
existing plants for severe accident vulnerabilities.
8 And number three, I will provida you with an 9
up-to-date status report of the implementation program itself.
10 May I have the first viewgraph, please.
l 11
[ slide.)
12 This viewgraph shows -- provides an overview of the 13 severe accident and source term implementation program.
You 14 see three items there.
The first one is the severe accident 15 policy statement action items, which I will summarize for you 16 to bring everybody up to the same point.
17 Then I will discuss the implementation program 18 elements, and finally the relationship with other programs.
19 Let's go to the next viewgraph, please.
4 20 (Slide.]
21 I have summarized for reference the key action items r
i 22 that emanate from the severe accident policy statement.
If 23 you recall, the policy was issued back in August of
'85, and l
24 the policy provides for criteria and procedural requirements 25 for licensing of new plants, and sets of goals and a schedule
... -.. ~ _. - -. _. -,. -.. - ~,. - _..... - -. -
-...,, ~, -. - - -
i 5
1 for the systematic examination of existing plants.
2 The policy statement deals with both future plants 3
and existing plants.
You see that for futura plants or for 4
new applications, as it is shown in the viewgraph, the 5
statement calls for the NRC to issue guidance on the role of 6
PRAs.
That is guidance regarding severe accident analysis in 7
decisionmaking.
For example, such things as quality of a PRA, 8
assessment of uncertainties, completeness, and things of that 9
sort.
10 on number two, regarding new applications, the 11 policy statement calls for whether to establish performance 12 criteria for containment systems and, if so, what form that 13 should take.
14 Moving to the right part of the viewgraph for 15 existing plants, the policy statement calls for the Commission 16 to develop a plan, an integrated systematic plan, to examine 17 each nuclear power plant in operation for possible significant 18 risk contributors which might be plant-specific and might be 19 absent without a plant-specific examination.
20 This statement, of course, came from the -- it was a 21 follow-up from -- it was a conclusion of the Commission at 22 that time that based on the existing information at that time, 23 the Commission showed no -- there was no reason to move 24 forward at that time for immediate action on generic 25 rulemaking, but because PRAs and other analyses always found
,y.m---
e<---
,,w,e.-
,.m.
, _g
_--.m
..,-,,_,_._-_,.-----_.s-%_..-.
-,m
_..--_m_,,%-
4 6
1 plant-specific vulnerabilities, the Commission decided to 2
pursue a more systematic evaluation of each plant, and if any 3
vulnerabilities were to be found, then the backfit rule was 4
going to be used to decide which cost-effective fixes need to 5
be implemented.
6 At the bottom of the viewgraph, I have listed the 7
generic changes that might be identified as necessary for 8
public health and safety will,.of course, be pursued through 9
rulemaking.
10 And this is basically a summary from the policy 11 statement.
12 Now if we go to the next viewgraph, I have a graphic 13 illustration of the elements of the implementation program.
14 (Slide.)
15 We mentioned the first one, the examination of 16 existing plants for internal initiators for severe accident 17 vulnerabilities.
We have provided you with SECY 86-76, which 18 describes this in great detail.
19 The second element is the examination of existing 20 plants for external initiators.
This effort is not going to 21 be done at the same time as for internal initiators.
The 22 reason for that was provided to you in SECY 86-162, Treatment 23 of External Events and Implementation of the Severe Accident 24 Policy Statement.
25 For future plants, I have listed the other element
9-7 1
guidance for future applications, and the other, on the right 2
hand, the use of new source term information in licensing.
I 3
For this we also have provided to you SECY 86-228, 4
Introduction of Realistic Source Term Estimates Into i
5 Licensing.
I will say more about it later on.
6 We have briefed your technical assistants on the 7
subject, and at your wish, we will be happy to brief you in 8
more detail on this particular staff proposal.
l 9
Moving to the next viewgraph.
10 (Slide.)
11 I will try again graphically to show the 12 relationship of the different programs that you people have 13 heard so many times how they relate to the implementation 14 program itself.
15 On the left side of the square, I have shown the 16 elements that provide the input to the implementation 17 program.
I have tried to separate them into kind of two 18 categories.
One of them is research-related.
The first three 19
-- if I can call them compressed circles -- the first three on 20 the left, understanding of phenomena, containment research and 21 analysis, source term research and NUREG 0956 and follow-up 22 effort.
I can categorize that as kind of research.
23 The other boxes reference plant analyses, IDCOR and 24 NRC, and the other three below I can characterize them as 25 application and experience.
~__
9 i
8 1
The NUREG 1150 that you were briefed on back in 2
December -- it's the first box, for example, reference plant i
3 analyses, the IDCOR and NRC.
The NRC refers to the NUREG 4
1150.
i j
5 Moving below the methodology for plant-specific 6
examination, we are working -- we have been working with IDCOR 7
for the last year and a half or maybe even longer very l
8 intensely in this area, and one of the things that they are i
9 coming up with is a proper methodology to do this examination f
10 for each individual plant.
i I
11 PRA studies and guides that provide insights into I
12 the development of guidelines and criteria that you mentioned, I,
13 Mr. Chairman.
And, of course, regulatory experience and I
}
14 generic issue resolution is an important ingredient in the j
15 implementation program.
16 To the right side of the rectangle is the output of 3
l 17 the program.
Generic letter to licensees on the l
i 18 plant-specific examination.
I will discuss that in some more 19 detail.
I i
20 Again, the guidance for future plants and, of I
21 course, the source term-related changes that we have already 22 undertaken.
23 If I move to the next viewgraph, I will get to the 24 subject now of the examination of existing plants for severe t
25 accident vulnerabilities.
l
9 o
9 1
(Slide.)
2 Again, this was the key part of the Commission's 3
policy statement.
I will describe the accomplishments, I will 4
tell you the essence of the proposed generic letter that we l
5 will be issuing.
We will say something about the acceptable 6
methodology for the individual plant examination, guidelines 7
and criteria, reference plant evaluation and then, of course, 8
I will discuss the schedule, so I can pick up each one of them 9
separate.
10 The next viewgraph, please.
11 (Slide.)
12 Accomplishments.
Both IDCOR and NRC updated 13 available PRA studies for reference plants.
The NRC work is 14 described in 1150 which, of course, will be issued for final 15 comment some time at the end of January.
16 The four plants are the Peach Bottom, Sequoyah, Zion 17 and Grand Gulf, and Surry.
18 IDCOR also has analyzed the first four plants; that 19 is, Peach Bottom, Sequoyah, Zion and Grand Gulf.
20 The 1150 effort also has extensive. work in 21 attempting to quantify the uncertainties associated with the 22 risk accessments.
23 As part of our interaction with IDCOR that lasted 24 back two or three years, we have identified a number of 25 technical issues and most of them we have agreed on the
9 10 l'
approach to resolving these issues.
2 We have had a large number of technical meetings 3
with IDCOR and, as I have said already, IDCOR has developed a 4
methodology for systematic plant examination.
5 We are putting together guidelines and criteria for 6
the plant examinations.
These guidelines and criteria will be 7
unique to the five types of plant; three for the boilers, Mark 8
I, Mark II, Mark III, and one for ice condensers, and one for 9
BWR dry containments.
10 Basically these guidelines are a list of the more 11 important severe accident related attributes that could i
12 contribute to either coremelt or containment performance or to 13 the risk itself.
14 We have drafted a generic letter, which again I will 15 tell you some of the -- its basic elements.
16 The next viewgraph discusses the generic letter.
17 The basis of the letter is the severe accident policy 18 statement itself.
19 (Slide.]
20 I have put in quotes the thing that we think gives 21 us the basis to get the letter out.
The Commission plans to j
22 formulate an integrated systematic approach to an examination i
23 of each nuclear power plant now operating or under I
24 construction for possible significant risk contributors.
25 Following the development of such an approach, an 4
~
,--n
.n,,----,,,,-
-,,---,----,--,.gn.-n,.,----
---,----,n,_,,m-
,, m es,,,__.a-ww.------r-n,_,---_--,
~,,~-
,.n
a.
11
'l announcement will be made of any plant that has not yet 2
undergone an appropriate examination.
3 Staff will issue the letter to each licensee 4
requesting a systematic examination to be performed by the 5
owner.
The letter will specify the scope of the examination 6
-- for example, what has to be covered, and in what detail.
7 In the letter we will identify acceptable methods 8
for the examination.
We will define documentation 9
requirements, and in the letter we will establish dispositions 10 for discoverable vulnerabilities and, of course, a schedule 11 will be set.
1 12 Last -- least, but not last, or again the other way 13 around -- I have to learn to say those things -- the Staff 14 will present this letter to the Commission prior to the
'l 15 issuance.
16 COMMISSIONER ROBERTS:
Haven't we in the past issued 17 generic letters for comment prior to issuing the letter?
18 MR. STELLO:
Yes.
i 19 COMMISSIONER ROBERTS:
Why, in something this J
l 20 significant, are we not entertaining the idea of issuing the 21 letter for comment?
22 MR. STELLO:
The Commission may choose to say that 23 when we give it to the Commission for approval.
24 COMMISSIONER ROBERTS:
You're not going to have a l
25 recommendation one way or the other?
12 1
MR. STELLO:
No.
We'll certainly think about it, 2
along with a --
3 COMMISSIONER ROBERTS:
I urge you to think about 4
that.
5 MR. STELIO:
But I think even before we send it out 6
for comment, I also think we need to come to the Commission.
7 COMMISSIONER ROBERTS:
Okay.
8 MR. STELLO:
To deal with the issue.
It may in fact 9
be appropriate to go out for comment, but let's -- we have 10 plenty of time to deal with that.
11 MR. SPEIS:
That has been done.
Our intent, all 12 along, at the time when the policy statement was finalized, 13 the agreement was that this letter will come to the Commission 14 for their approval before it goes out.
15 COMMISSIONER ROBERTS:
Fine.
16 MR. STELI.0:
We might want to consider having the 17 comment period before the Commission deals with it, too.
18 We'll need to deal with that.
It might be wise to have some 19 at least preliminary interaction.
We need to sort that out.
20 We're not ready.
21 CHAIRMAN ZECH:
All right.
22 COMMISSIONER BERNTHAL:
How long do you envision the 23 process taking?
24 MR. SPEIS:
The letter -- we will give you the 25 schedule shortly.
13 1
COMMISSIONER BERNTHAL:
Okay.
2 MR. SPEIS:
One of the things that we are trying 3
very hard to accomplish, to accommodate, is to stay within the 4
schedule.
As you recall, the policy statement was issued in 5
August of '85, and the statement called for a two-year period 6
to get these things done, and we are trying very hard to stay 7
within that period.
8 The next viewgraph discusses the acceptable 9
methodology for the plant-specific examination.
Basically one 10 of them is the IDCOR individual plant evaluation methodology 11 that,they are developing and we are reviewing, and hopefully l
12 we will reach an understanding with them in the next month or 13 so, agreement that this is the appropriate methodology.
14 Another one could be a Level 2 or 3 PRA.
Level 2 15 PRAs, systems analysis plus containment performance.
Level 3 i
16 goes beyond and includes consequence analysis and health 17 effects.
It could be a Level 1 PRA with source term part of 18 the individual plant examination methodology.
It could be
(
19 some more simplified PRA with NRC approval.
It's a so-called l
20 abbreviated PRA or smart PRA that people have characterized in 21 the past, or some other systematic evaluation, so that a 22 utility chooses to put together.
I don't think we should 23 discourage them from coming, a utility smart enough that they 24 have a good way of doing this individual plant examination, we 25 shouldn't be dogmatic and say only one method is acceptable.
14 1
Regarding the IDCOR individual plant examination 2
methodology, they have submitted appropriate documentation for 3
our review.
We had a workshop with them.
They have applied f
4 the methodology *to a number of plants, so they can refine it 5
and finetune it.
We have provided some comments to them.
The 6
ACRS has done some review, and is in the process of doing some 7
additional review.
In fact, a meeting will take place Friday 8
to further discuss these.
As a result of our comments and the 9
ACRS review, IDCOR is doing so=c revision and finetuning of 10 the methodology, and we hope that some consensus will be 11 arrived at shortly that the methodology is acceptable to be 12 utilized -- one of the acceptable methodologies.
I 13 COMMISSIONER ASSELSTINE:
Themmy, could you just 14 highlight the key elements of the IDCOR evaluation method as it exists today, and particularly to what extent does it rely 15 16 upon using the reference PRAs or the reference analyses for a 17 few plants as the jumping-off point or the basis for a more 18 abbreviated evaluation of the remaining plants?
19 MR. SPEIS:
You characterize it very well.
Basically the jumping point is the reference plant analysis.
20 l
21 And beyond that, the focus will be on plant-to-plant 22 variations, and what are the important things that contribute 23 to risk.
24 For example, from all the insights that have been 25 developed the last 10 or 15 years, we find out that the
15 1
support systems or service support systems are so crucial, 2
that if a plant varies from the reference plant in its support 3
systems, then those support systems would have to be analyzed 4
in some detail, and the methodology itself calls for that.
5 So it is basically a reference plant, and then treat 6
the differences to an extent consistent with the insights that 7
now, you know, there are some arguments about how you go into 8
the fault tree level and how far down the chain you go, and 9
these are the types of things we are discussing with them.
10 In essence, this is the methodology.
11 COMMISSIONER ASSELSTINE:
I guess one of the big 12 questions I have always had is to what extent, given the wide 13 variations from plant to plant, that kind of an approach is 14 likely to be successful, and I guess I would say if you look 15 at the Indian Point PRA, one of the things that we found out 16 from that is that a dominant contributor risk there was the 17 structure of the building itself, the fact that the buildings 18 were built so close together that they'd bang together in a 19 seismic event and the roof would fall in.
20 If you look at the Oconee PRA, one of the dominant 21 contributors to risk there, as I recall, was the flooding 22 question.
23 If you look at the Zion PRA as your base model, how 24 would that have pointed you to those two plant-specific 25 vulnerabilities that turned out to be significant contributors
16 1
to risk?
Would it have told you to even look at those things?
2 MR. SPEIS:
Well, another thing that we are doing in 3
addition to the methodology, we, as I said, cryptically -- or 4
not cryptically -- early on we are putting together guidelines I
5 and criteria which is kind of the wisdom accumulated over the 6
last 20 years, not only from PRAS, from operational 7
experience, but I am sure that this methodology or any other 8
methodology is not, you know, the and of the world.
You know, f
9 I don't think you can say that every conceivable vulnerability 10 will be able to be identified, you know.
11 The thing that we have to keep up with -- keep up 12 with operational experience, maintenance, you know, the whole 13 infrastructure that we have in place.
Not one specific system 14 will be able to solve all our problems and keep our plants 15 safe.
So it is that ensemble of everything that we have in 16 place.
17 COMMISSIONER ASSELSTINE:
Okay.
18 MR. SPEIS:
I don't know if anyone can answer any 19 more.
20 COMMISSIONER ASSELSTINE:
Well, if you get to the 21 point where you are talking about the guidelines and criteria, 22 I guess I would be interested in hearing some more about how 23 those are going to suppledent.
But am I right in basically 24 saying that if one were to look at the Zion PRA, if that were I
i 25 your reference once, and you hadn't done a PRA on Indian Point
17 1
or on Ocones, that work wouldn't lead you to what were 2
dominant contributors to risk for those two plants?
Am I 3
right about that?
4 MR. SPEIS:
Well, again -- but this is the reason 5
that we are going for the plant -- individual plant 6
examination, because of these unique things that were found in 7
every plant.
8 COMMISSIONER ASSELSTINE:
So that individual plant 9
examination has to be awfully detailed to pick up each of the 10 individual vulnerabilities.
11 MR. SPEIS:
Well, again, you know, there is always 12 cost-benefit and how you go.
13 Maybe, Zoltan, you want to add something.
14 COMMISSIONER ASSELSTINE:
Is that sort of the key 15 issue on whether you can trust or accept this IDCOR 1G methodology?
Is that really the gut issue?
17 MR. ROSZTOCZY:
Yes, that is probably the biggest 18 issue, is whether they have the capability to pick up 19 vulnerabilities.
It was designed, the methodology was i
j 20 purposely designed to be able to do that, and it does look l
21 into the plant in detail.
It assumes that first that you look 22 at reference plants work, like the event trees drawn up and l
23 fault trees drawn up for the reference plant.
l 24 Then you ask the question, if those are applicable 25 to your plant.
And in areas that they are not directly
18 1
applicable, because the plant design is somewhat different, 2
then you are supposed to provide your own, and it provides 3
guidance for it, and asks questions from you that you have to 4
answer in order to provide for your own plant, and then feed 5
it into the plant analysis.
6 So it should be able to pick it up, theoretically.
7 Does it pick it up in practice is a somewhat different 8
question.
In order to show that how does it work in practice, 9
they have already applied it to five plants, and they are 10 still applying it to two or three more.
11 So by giving you the actual application and see how 12 did it work out gave us a little bit more insight how does 13 someone who follows the instructions given in the book goes 14 into these details, and how far he gets before he goes back 15 again.
16 COMMISSIONER ASSELSTINE:
For those other five to 17 eight plants, did they take -- do a parallel review?
One, do 18 the IDCOR review and see what the results from that were; and 19 second, do a top to bottom complete PRA, complete 20 plant-specific review, and then compare the results to find 21 out how good the IDCOR methodology really worked?
22 MR. ROSZTOCZY:
Ideally the best would be if you 23 have these two completely separate.
We don't exactly have l
24 that.
They have done the so-called IDCOR evaluation of the 25 plant, which is a relatively complicated evaluation based on l
l
19 1
the old PRA updated to today's knowledge, and completely 2
separately gave'the instructions -- which, by the way, is a 3
big package, it's not a small item -- gave these instructions 4
to the utility, and provided some help for the utility just to 5
have them to go through, and these people who were not 6
involved in the other work followed the instruction and they 7
applied it.
8 So it's as independent as reasonably one can expect, and going through the instruction, they did run into certain 9
10 things, and they didn't in others.
So I think it does provide 11 some background.
12 COMMISSIONER ASSELSTINE:
Okay.
13 MR. ROSZTOCZY:
It's not perfect.
14 COMMISSIONER ASSELSTINE:
Okay.
Go ahead.
15 MR. SPEIS:
Next viewgraph, please.
16
[ Slide.]
17 As I said already, we are putting together 18 guidelines and ideas for five specific type of plants.
I 19 mentioned them already.
The three Mark type of containments, 20 the large dry, and the ice condenser.
And again, these 21 guidelines and criteria are based on insights from NRC and 22 IDCOR reference plant analyses, PRAs, LERs, basically, you 23 know, all the wisdom that we have accumulated over the last 20 24 years.
25 COMMISSIONER ASSELSTINE:
How are you going to deal
=.
20 1
with the B&W and the CE plants?
Particularly B&Ws?
They're 2
such unique beasts.
3 You've got the containment types covered, but B&Ws 4
seem to have such unique characteristics in terms of 5
performance and sensitivities.
6 MR. ROSZTOCZY:
Well, some of the B&W plants have 7
PRAs, and those PRAs have been brought to bear, you know, the 8
insights, even though the reference plants don't contain the 9
B&W.
And, of course, the guidelines and criteria also draw 10 insights from PRAs and other experience based on B&W plants.
11 COMMISSIONER ASSELSTINE:
Was the Oconee PRA a full 12 ccopo PRA?
13 MR. ROSZTOCZY:
It was a full scope PRA, yes.
14 COMMISSIONER ASSELSTINE:
But that's not serving as 15 one of the reference plants?
16 MR. STELLO:
I think the answer to the question is 17 that you have at least some of those B&W plants.
1 18 COMMISSIONER ASSELSTINE:
But apparently they are 19 not serving as reference plants for the IDCOR effort.
l 20 MR. STELLO:
They, by definition, exist to provide 21 the insights to determine if there are any vulnerabilities 22 unique to those plants, and you have at least several of them 23 to call on.
24 COMMISSIONER ASSELSTINE:
Okay.
25 MR. SPEIS:
We have attempted to provide a balance
21 1
between prevention and severe accident mitigation in these 2
guidelines and criteria.
Ycu know, always the question is, 3
you know, what's the yardstick, and there always we have to' 4
walk a tightrope, you know.
Basically we use the safety goal 5
as a guidarce, cost-benefit analysis and all the other things 6
that are in existence.
7 We are in the process of implementing the generic 8
guidance and safety goal, and that also will be utilized to 9
some extent.
10 COMMISSIONER ASSELSTINE:
How are you striking that 11 balance, Themmy?
The Staff has told us that when you look at 12 Mark Is, there ain't much balance there.
If you've got 13 protection, it's almost all on the prevention side.
How are 14 you striking the balance in terms of what you are trying to 15 achieve here?
16 MR. SPEIS:
Well, when we put the -- when the 17 individual plant examinations are completed, and the 18 guidelines and criteria are taken into account, if some 19 containments deviate from criteria such as 10-6 per reactor 20 year for large releases, we will have to see what cost-benefit 21 or other practical efforts can be done to bring a balance.
22 COMMISSIONER ASSELSTINE:
But you are just looking 23 at the overall numbers?
24 MR. SPEIS:
Yes.
25 COMMISSIONER ASSELSTINE:
So that it could be all on
22 1
the prevention side.
2 MR. SPEIS:
Not necessarily.
Not necessarily.
I 3
think it's too premature.
I think we were trying to strike a 4
balance, and if some probable consequences lead to early 5
containment failure, I'm sure we're not going to let it go by.
6 MR. STELLO:
You remember when we were talking about 7
the Mark I containment briefing, I said that I think this 8
raises for us all of those questions.
It raises the issue of 9
mitigation, prevention, containment performance criteria, the 10 application of the Commission's safety goal policy, risk 11 reduction versus mitigation is an interesting question.
I 12 gave you the examples of the two PRAs that were done were 13 coming out with in one case 99 percent of the risk was station 14 blackout, and the other was, I think, 90 percent.
You know, 15 why do we want to try to approach containment without dealing 16 with that question, too?
17 I have directed the Staff that when they consider t
18 this issue, they are to raise all of those questions and try 19 to understand how to bring all of these issues to bear, 20 because they are all relevant and pertinent, and there are no 21 easy answers.
22 I don't know that we have an answer.
We are going 23 to have to evolve it.
We are doing something for the first 24 time on the Mark I's that is going to raise the issue, and it 25 will start to teach us and tell us how to move forward.
And
23 1
as you are aware, we will be back to the Commission.
It is 2
not an easy question, and there aren't any easy answers.
3 There will be a judgment that has to be made.
The final 4
analysis is in fact the judgment, and it will be the 5
Commission's judgment as to how to proceed.
6 COMMISSIONER ASSELSTINE:
So all you are really 7
doing here is asking the plants to find out what the situation 8
is?
9 MR. SPEIS:
Yes.
I 10 COMMISSIONER ASSELSTINE:
Not to do anything, to do 11 an analysis --
12 MR. SPEIS:
List the vulnerabilities, and then tell 13 us what they are going to do with them.
14 COMMISSIONER ASSELSTINE:
Okay.
At some point down 15 the road we have got to make the decisions about what do we 16 want in terms of containment performance.
Do we really want 17 containments that aren't going to work if you have a core 18 meltdown.
19 MR. STELLO:
We are going to face that issue before i
l 20 that.
As I said, you're going to be facing it on the Mark I, 21 as to how to make that judgment.
So before you get these 22 analyses in, we will have had at least several examples to 23 have to deal with that will teach us all what to do.
We can't 24 answer a question we can't answer.
We don't have the answer.
25 COMMISSIONER BERNTHAL:
You know, I don't want to
=
24 1
launch into Homily 1.B.3 here, but again I have got to say 2
that it is going to be hard for the Staff to decide how to 3
trade off prevention and mitigation unless we, the commission, 4
finish up this safety goal business.
We haven't told you what 5
we want to do, and it can cut both ways.
6 I, for one, would strongly support a system which I 7
guess Fort St. Vrain was believed to be, and may well be, that 8
offered such a very low coremelt or severe core accident 9
probability that you essentially can write off the 10 containment.
We don't have many proposals for that kind of 11 plant on the table at this point, but we aren't prepared to 12 deal with that, either.
And somehow we have got to make a 13 fundamental policy decision before we can expect you guys to 14 know how to make the tradeoff between containment and 15 coremalt, and we haven't done that.
16 Otherwise, you are going to wing it and do the best 17 you can, I understand that, but I'd prefer that we did it.
18 MR. STELLO:
Well, we are going to look at the issue 19 and raise all of those interrelated complex questions and be 20 back to you as part of our response to deal with this issue on 21 the Mark I containment question, and I have directed the Staff i
22 that they will in fact consider all those things and you at 23 that point will have to be making those judgments.
24 I think it is probably not one that can be made in 25 generalities.
We are going to have to take some specific
9 25 1
examples to really get the insights and the understanding of f
2 how to pull that all together.
And you have one, and it's a 3
real one, and it will be coming to you.
4 CHAIRMAN ZECH:
It's important in my view to look at 5
prevention issues, to look at mitigation issues, and in accord 6
with our defense-in-depth theory, to look at them together.
I 7
think that is what we are trying to do, and we are trying to 8
do it in a responsible manner.
9 Jim, go ahead.
10 COMMISSIONER ASSELSTINE:
I was just going to say 11 that I agree with that, Lando, although I do think Fred's 12 right, that there are some fundamental decisions here that 13 need to be made on that tradeoff, what it is that we are 14 looking for, and it's certainly better to make those sooner 15 rather than later.
16 MR. STELLO:
I assure you, you are going to be faced 17 with them sooner, not later.
18 CHAIRMAN ZECH:
I think we are moving towards making
{
19 those decisions, again in a responsible manner.
I think so, 20 and I think we should, too, and I agree.
21 COMMISSIONER ASSELSTINE:
And I think as far as 22 existing plants are concerned, with the possible exception of 23 Fort St. Vrain, Fred, we are not at the point where we've got 24 the designs that we're really comfortable, that you've got 25 this huge margin on the prevention side so that you could give
26 1
up on the mitigation side altogether.
Quite the contrary.
2 COMMISSIONER BERNTHAL:
Yes, I mean that's the 3
fundamental issue on the Mark I's, is the coremelt probability 4
so spectacularly low that you are prepared to abandon the 5
defense-in-depth concept.
I suspect it is net, and if we are 6
told that 90 percent, 50 percent, maybe even 20 percent 7
probability of containment breach in a coremelt -- I know you 8
guys have heard this all before -- it's my judgment that is 9
not then in the spirit of defense-in-depth.
If you come in 10 with a spectacularly low coremelt probability, there comes a 11 point where I suppose you don't put a 50-mile an hour bumper 12 on an automobile, but --
13 COMMISSIONER ASSELSTINE:
Plus real assurance that I
14 in fact that's a real number, that the plants are going to be i
15 operated and maintained in a way that that number is really 16 likely to be --
1 17 CHAIRMAN ZECH:
Well, as real as we can de, in this 18 technology we're involved in.
19 MR. STELLO:
I don't think we are prepared to help 20 the Commission on this issue at the moment --
21 COMMISSIONER BERNTHAL:
No, I understand that.
22 CHAIRMAN ZECH:
Well, that's why we're here, it's an 23 important issue you're talking about.
You know, 24 defensc-in-depth is a basic part of our safety philosophy in 25 our country.
I submit that we be very careful before we move
27 1
away from it, but that's why we're here this afternoon, and I 4
2 suggest we proceed.
3 MR. SPEIS:
Zoltan, do you have a comment?
4 MR. ROSZTOCZY:
Just basically the way we are 5
presently handling it, we are locking at the prevention, and 6
we are -- in terms of prevention, we are looking at the 7
Commission's statement in the safety goal policy statement, 8
that they don't want to see severe accidents.
9 Then separate from this, we are looking at 10 mitigation.
We are measuring the mitigation against the 11 10-6.
So if there is a plant which doesn't meet the 10-6, 12 then it has two possible ways to correct it:
13 One of them is if you take the event which resulted 14 in a large release and reduce the likelihood of that event, so 15 you do something, you modify the plant to reduce the 16 likelihood of this event and to move it below the 10-6; or 17 alternately, you can strengthen the containment so the 18 containment can hold up for that case.
By leaving both of 19 these ways open for the designer, we are striking kind of a 20 balance between the two that both type of correction is 21 available, and at the same time both of the basic goals are 22 met.
23 Now in terms of containment, do you really -- do you
- 24 have to have a containment, we are using this as an additional 25 severe accident type of need or requirement in addition to the
..__.___._-m.__,,y
28 1
existing requirement on design basis accident.
So if somebody 2
has an extreme -- like a future design, a new design, able to j
3 reduce all of their event in such a low probability that that 4
they fall below this 10-6 idea, there still remains the 5
containment requirement in terms of design basis accident, 6
they still would have to have a containment to the extent as 7
it's required by the present regulation.
So that is the 8
fallback position.
9 COMMISSIONER ASSELSTINE:
Yes.
But recognizing that 10 the Mark I containments, as they currently exist, meet those 11 requirements, with a high probability of containment failure 12 in the event of a coremelt accident.
13 MR. ROSZTOCZY:
Therefore they are covered for 14 design basis accident, and whether they are sufficient for 15 severe accidents that would come out from these two additional 16 checks.
If it doesn't, then they have to do something.
17 COMMISSIONER ASSELSTINE:
Okay.
My point being that 18 at least as far as Mark I's are concerned, the design basis 13 cccident doesn't give you a whole lot of comfort in terms of 20 additional protection for severe accidents.
21 MR. ROSZTOCZY:
But if somebody would change the l
22 Mark I's so the likelihood of all of the event which 23 challenged the containment was far, far down below, then you 24 would be comfortable with the present container.
I 25 COMMISSIONER ASSELSTINE:
Yes.
And assuming the i
29 1
methodology is truly valid, and that you can --
2 MR. ROSZTOCZY:
Right.
Right.
3 COMMISSIONER ASSELSTINE:
-- really count on there 4
not being some other things out there you don't know about.
f 5
MR. ROSZTOCZY:
Right.
6 CHAIRMAN ZECH:
All right, let's proceed.
7 MR. SPEIS:
Next viewgraph.
8
[ Slide.)
9 I have the schedule here.
Basically our present 10 schedule, which is extremely tight and optimistic, is to bring 11 the generic letter to you some time at the end of February.
12 Before that we will have gone to the CRGR.
We are going to 13 discuss this with the ACRS this week.
14 The schedule again shows the letter being issued at 15 the end of March, but Mr. Stello said possibly we might want 16 to send it out for some comments ahead of time.
That's 17 something we will have to discuss, I think, farther.
18 CHAIRMAN ZECH:
But this means that all the 19 individual plant examinations will be done essentially within 20 the next two years; is that correct?
21 MR. SPEIS:
Yes, this is correct.
The next to the 22 last date on there --
23 CHAIRMAN ZECH:
It would be 18 months, so two years 24 from now, or a little less than two years from now.
I 25 MR. SPEIS:
Yes.
i l
30 1
CHAIRMAN ZECH:
Okay.
2 MR. SPEIS:
The last viewgraph studies and reports 3
on implementation program.
4
[ Slide.]
5 We are developing guidance for new plants, as well 6
as containment performance criteria for new plants.
We will 7
be discussing that with you in February.
As I said today, we 8
are focusing on existing plants.
9 COMMISSIONER ASSELSTINE:
Are you going to have 10 something, a proposal for us, in February?
11 MR. SPEIS:
Yes.
12 COMMISSIONER ASSELSTINE:
On containment performance 13 criteria?
14 MR. SPEIS:
Yes.
15 COMMISSIONER ASSELSTINE:
All right.
I 16 CHAIRMAN ZECH:
The answer is yes, I gather?
17 MR. SPEIS:
Yes, the answer is yes.
18 The third part of the implementation, introduction 19 of realistic source term into licensing.
As I said earlier, 20 we have provided you with our proposal, SECY 86-228.
We have 21 discussed this with your technical assistants, and we would be 22 happy to discuss it farther with you.
23 In essence, this is an attempt to get away from the 24 arbitrariness of the present approach, where you arbitrarily 25 dump a source term into the containment without any
31 1
consideration of the realities of physics and chemistry, and 2
the only thing that you do after that is you allow it to leak 3
at some leak rate which is something close to.1 percent per 4
day, and the new approach will attempt to realistically 5
account for the phenomena that we have learned the last five 6
or 10 years, especially from the last two years, from the 7
intensive efforts involved from our Office of Research.
8 We have already completed our -- the next two items 9
involve two important issues that deal with the -- how we 10 treat and evaluate and provide design guidance regarding the 11 areas of PWR containment spray additives and BWR suppression 12 pool decontamination factors.
13 We have completed our evaluation of these two areas, s
14 and we are proposing changes to the Standard Review Plan in 15 those two areas.
Our office director has sent the packages 16 for those two areas to the CRGR and hopefully once they pass 17 CRGR, they go out for public comment.
}
18 What we are doing in this area again, we are taking 19 reality into account regarding the PWR containment spray 20 additives.
We are proposing to delete the requirement that 21 you add chemicals during the spray injection period, but we 22 will continue to require control of the sump pH.
23 This requirement is not going to affect safety in 24 any way, but it will prevent inadvertent actuation of the 25 sprays, which would avoid problems like corrosion and l
i
32 1
deterioration of the plant in general.
2 In the other area, BWR suppression pool 3
decontamination factors, at present we do not give any credit 4
for decontamination, but we have ample information from all 5
the research that ha's been done that this is not correct, so 6
the proposal is to change that, and we allow for a realistic 7
calculation of decontamination, taking into account the 8
temperature of the pool and everything that we have learned.
9 For example, particulates, we can give credit of at 10 least a factor of 10.
Iodine, probably a factor of 100.
And 11 if those factors are claimed, we might not even need a 12 calculation from the licensees unless they think that they can 13 justify some additional decontamination factors.
14 So in those two areas, we have completed the work, 15 we have sent the packages to CRGR, and hopefully they will go 16 out for public comment.
17 So those are two specific areas where the research 18 of the last two years hopefully will enter our regulations.
19 The last -- the next one, revising the regulatory 20 guide 1.3 and 1.4, again this is the prescriptive of 21 calculating the source term that is used in evaluating a 22 number of things in our regulatory framework, including siting 23 of nuclear power plants, including equipment qualification, 24 including a number of other issues.
25 Again, this is the arbitrary source term of 25 or 50
33 1
percent iodine, 25 percent plating out, 100 percent noble 2
gases.
But again here is the -- in this area we would like to 3
use the realistic approach and take into account all the 4
processes that we have learned are physically applicable and 5
realizable in the primary system and the containment.
6 The last issue that I have listed here, emergency 7
planning reassessment, when we discussed the implementation 8
program with you a year ago, if you recall, we listed the 9
short term changes and the longer term changes.
I think we 10 are keeping our bargain on the short term changes.
This one 11 fell out under the long term changes, and the schedule 12 probably will slip somehow, because it depended on having the 13 information available from NUREG 1150.
14 I think when Dr. Ross discussed this issue with you 15 last time, he said that we are doing all kinds of parametrics 16 and other calculations to make sure that what is relevant in 17 this area is properly accounted for.
18 So this is the only area that probably will slip 19 from the schedule that we gave you a year ago.
Again, this 20 area was very closely coupled to the 1150, and the 1150 21 somehow has slipped since that time, and so will this area.
22 So, Mr. Chairman, with this, I complete my 23 presentation.
24 CHAIRMAN ZECH:
Thank you very much.
25 Just one comment on your source term continuing
34 1
research, I trust you are going to include in that research 2
everything that we have learned so far and can learn on the 3
Chernobyl incident.
4 MR. SPEIS:
Yes, yes, yes.
Dr. Ross will discuss 5
this, but when we briefed you on the Chernobyl accident, the 6
implication was -- in January, I guess this briefing was 7
supposed to take place, we will tell you exactly what we have 8
learned that is relevant regarding the source term, and what 9
additional things we plan to do as a result of that.
10 CHAIRMAN ZECH:
Fine.
I appreciate the fact that 11 Research is involved heavily in that, but also I think in the 12 programs that we are dealing, you should be mindful of the 13 responsibility.
14 MR. SPEIS:
Yes.
It is always -- it is taken into 15 account, but we will tell you more explicitly in January what 16 are the specific areas that we think we have learned from 17 the Chernobyl accident as regards the source term itself.
18 CHAIRMAN ZECH:
Fine.
Very good.
i
)
19 Do my fellow Commissioners have questions before we
{
20 turn to Dr. Ross?
i 21 COMMISSIONER ASSELSTINE:
Just a couple.
22 Themmy, what is your plant schedule on the emergency 23 planning reassessment?
24 MR. SPEIS:
Emergency planning, the most optimistic right now is to review interested proposals in February '87, 25 i
35 1
assess results from the technical basis studies that Dr. Ross
'2 described last time, May '87, factor in Chernobyl and other 3
experience, at the same time ACRS hears our review some time 4
in June, prepara option paper and forward for commission 5
action August '87.
6 (Commissioner Roberts left the room at 2:50 p.m.]
7 MR. SPEIS:
And this is a schedule that hasn't been 8
discussed with my management, so I'd have to --
9 COMMISSIONER ASSELSTINE:
Okay.
10 CHAIRMAN ZECH:
It's going to be your 11 recommendation, is that right?
12 MR.-SPEIS:
Yes, it will be my recommendation.
13 CHAIRMAh ZECH:
All right.
Thank you, i
14 COMMISSIONER ASSELSTINE:
Couple of others.
NUREG 15 1070 had listed both for existing and future plants a whole 16 series of policy papers that were to be prepared.
17 MR. SPEIS:
Excuse me, is that the policy statement?
18 COMMISSIONER ASSELSTINE:
NUREG 1050, yes, yes.
19 Policy on future reactors.
But both for existing and future 20 plants, it listed a whole series of policy papers that were to 21 be prepared in, I guess, '84 and '85 that would focus on a 22 variety of aspects that affect the severe accident risk and 23 severe accident issues, design questions, construction, 24 operating experience, a whole series of those.
25 Have those all been done?
Have they been factored
36 1
into the guidelines and criteria that you are setting up for 2
these initial plant reviews?
3 MR. ROSZTOCZY:
At one time it was considered 4
approached by writing a set of these papers, and some work was 5
initiated in that time frame that you mentioned, in
'83,
'84, 6
or maybe '85 time frame.
But it has not been pursued since 7
the Commission's policy statement was issued.
8 Instead, we followed very closely what the policy 9
statement specified in terms of providing additional 10 requirement in preparing for the individual plant examination.
11 (Commissioner Roberts reentered the room at 2:52.]
12 COMMISSIONER ASSELSTINE:
Okay.
13 MR. ROSZTOCZY:
But the background information that 14 was put together at that time, that has been discussed with 15 the people and the work that was ongoing, so the knowledge and 16 the information has been factored in, l
17 COMMISlIONER ASSELSTINE:
How much worP was done on 18 some of these things before it was stopped?
Enough to give 19 you some real insights'into the potential contribution of 20 design errors and construction errors to severe accident risk?
21 MR. ROSZTOCZY:
Most of the work was done in 22 connection with preparing the policy statement draft and the 23 report that you have in front of you, which was issued 1
24 together.
That was most of the work which was done at that 25
- time, l
37 1
In addition to that, another area where there was 2
work done at that time was the review of some of the PRAs by 3
the GESSAR PRA.
4 COMMISSIONER ASSELSTINE:
Okay.
In terms of the 5
external contributors to -- external accident initiators, how 6
have you factored in -- there was a Board notification back in 7
'83 on seismic risks to boilers that indicated that the 8
seismic vulnerability of BWRs was considerably higher than 9
WASH 1400 had predicted.
And also to what extent have we 10 factored in the new information from USGS in '84 on the 11 Charleston earthquake and the potential vulnerability to 12 plants in the East from seismic risk?
Is that factored in at 13 all on the external contributors?
I i
14 MR. ROSZTOCZY:
We have not done that yet.
The 15 external contributors work has been initiated on the external l
16 contributors, but we are starting with some of the other 17 contributors; namely winds and floods are the first two that 18 we are doing.
The seismic will probably be the last one that l
19 we will be doing, simply because the methodology for seismic 20 events is still under development.
Both EPRI and Research are 21 developing methodologies for that.
We are kind of waiting for 22 that, and because of this we put the seismic at the end of the 23 list, and we are doing the other initiators first.
24 But it is our intent to factor both of those into 25 that.
l
38 1
MR. SPEIS:
Mr. Asselstine, what Zoltan has said, 2
plus more details, are described in SECY 86-162.
3 COMMISSIONER ASSELSTINE:
Okay.
Just as an aside on 4
the Charleston earthquake, is the clarification of the USGS 5
position still on track?
We're supposed to get that, I 6
gather, the end of
'86, which is almost here, according to 7
Dircks' paper back in
'84.
Is that still on track, or has 8
that slipped?
You can find out for me.
9 MR. ROSZTOCZY:
Lots of work has been done on that 10 on seismicity, and there are some new results which are very 11 close to being completed.
I believe so.
It's closed to that.
12 COMMISSIONER ASSELSTINE:
Great.
13 MR. SPEIS:
We will provide you information.'
14 COMMISSIONER ASSELSTINE:
Great.
That's fine, i
15 Last question.
You mentioned that once you found-16 the vulnerabilities, you'd go back and take a look and decide 4
17 at that point what had to be done to fix them up, and you 18 mentioned the statement in the commission's Safety Goal Policy 19 paper, that we don't want to see core degradation accidents at
(
20 any U.S. plant.
1 21 How are you going to go about making those decisions 22 in terms of if you see vulnerabilities, what changes have to 23 be made?
Is cost-benefit analysis going to play a role in 24 making those kinds of decisions?
And if so, how is that 25 process going to work?
And at the same time, meet the stated
~
39 1
1 objective in the Commission's Safety Goal Policy Statement, 2
that we intend the regulatory process to function in a manner 3
that won't result in core degradation accidents at any plant.
4 MR. ROSZTOCZY:
Well, your question, how we're going 5
to translate those statements into real hardware or numbers or 6
whatever, and we are in the process of doing tDat, and maybe i
7 Mr. Stello or Mr. Speis can say more about that.
8 COMMISSIONER ASSELSTINE:
It seems to me that goes 9
hand in hand with the containment performance standard.
10 MR. STELLO:
Well, no, not at all.
They are two 11 completely different topics.
You are talking about preventing 12 an accident, and a containment deals with mitigating an 13 accident,so they are two completely different questions.
14 COMMISSIONER ASSELSTINE:
But they're two halves of 15 the severe accident --
16 MR. STELLO:
Well, it's clearly the issue that we 17 talked about for 10 minutes before.
It's prevention versus 18 mitigaticn.
19 COMMISSIONER ASSELSTINE:
Yes.
20 MR. STELLO:
The Commission does have in place a l
21 backfit rule that when we backfit a plant, we will be 22 following that rule.
I assume that's clear, that we are to 23 follow the rules.
The rules tell you what to do.
There is a 24 procedure in place of how to implement that rule.
The 25 Commission has reviewed it, and that's what we will be i
-,_,_,m_..
40 1
following.
2 There are more difficult questions, I think, in 3
terms of how to balance all of those.
When you start to ' raise 4
the question of prevention and mitigation, putting the two of 5
them together and how you integrate them, that are clearly 6
going to be more difficult.
7 I go back to what I think is the Mark I issue, 8
because I said I think I don't want to see the Mark question 9
raised without raising the prevention question.
I think it's 10
-- if we can, for even less money than it would take to deal 11 with modifying containments, reduce risk a factor of 10, I 12 would think I would be hard pressed to come down here and 13 argue with you that we ought to work the other side of the 14 equation and just ignore the prevention side, when an equal 15 amount of money would have an overall reduction in risk and 16 maybe dealing with the containment might change that a factor 17 of --
18 CHAIRMAN ZECH:
Not only money, but safety.
19 MR. STELLO:
Safety.
And I think we -- those are 20 difficult questions.
We are q iing to do our best to deal with 21 them and have some reco.ttenJ;r3cns and bring them down to the 22 Commission.
I think they are basically reduced to the same 23 question.
24 COMMISSIONER ASSELSTINE:
Okay.
One last question.
25 Do the utilities have the kind of knowledgeable expert people
41
. to do these reviews all at once in an 18-month period of time?
2 MR. ROSZTOCZY:
It's a very important part of this 3
examination, that the utility play an important role in it, 4
because it is important for them to understand what are the 5
potential ways that can go wrong in their plant, and to 6
understand how to face them, so we expect them to play an 7
important role.
But they will need some help, and we expect 8
-- it's expected that they will be contracting with somebody 9
to do this.
10 A group of companies already got together and formed 11 a partnership just for this purpose for the PRA practitioners 12 that are available for this purpose also.
The generic letter 13 is set up in a way that after they receive the generic letter, 14 they will have two or three months just to think over what 15 they would be doing, whom they would be doing it with, line up 16 those, and then reply back to us and give us a commitment for 17 a date.
This period, this two to three months period, would 18 be the time when they would be making those arrangements and I 19 think it is very likely that there will be enough available.
20 COMMISSIONER BERNTHAL:
You know -- excuse me a 21 minute.
I've got to say thtt that was a concern that I had on 22 looking at your objectives here, that within -- how does it 23 go, six to 12 months, those that have plant-specific PRA in 24 some depth already manage it in six to 12 months, and then the 25 hundred odd plants that we have in this country, most of them,
42 1
I guess -- I don't know how many complete PRAs we have --
2 MR. STELLO:
About 30.
3 COMMISSIONER BERNTHAL:
About 30.
So we've got-70 4
out there that do not have -- is that not true?
5 MR. ROSS:
We're double-counting.
Some of these 6
count double units.
You may be up to 50 percent.
7 COMMISSIONER BERNTHAL:
Okay.
Well, leave it at 50, 8
then.
But my point is that I think it's quite certain that 9
the average utility probably does not have the expertise to do 10 an in-house, detailed PRA.
There is going to be a lot of 11 contractor work done here.
12 I would be very surprised if there was the expertise 13 out there in the contracting world to carry that off in 18 14 months, or whatever the target date is here.
Do you believe 15 there is?
I 16 MR. STELLO:
No.
Not if each of them are going to 17 do a full scope PRA.
But that isn't what's required.
You 18 remember, IDCOR has been working for a long time developing a 19 methodology, which we are in the final stages of approving, 20 which falls far short of having to do that kind of thing.
But 4
21 if you'd asked the question, what you have on your mind, each 22 of them doing a full scope PRA, that is not based on that 23 assumption at all.
24 COMMISSIONER BERNTHAL:
But I understand you use a 25 reference plant and then you jump off at some point to
43 1
plant-specific analyses, I guess.
That still requires quite a 2
bit of expertise, it seems to me.
We've talked about doing 3
so-called smart PRAs.
You know, the word speaks for itself.
4 You are going to have to have people who know what they're 5
doing.
6 MR. ROSZTOCZY:
We have discussed this with the 7
industry.
We have outlined to them roughly the dates what we 8
had in mind, and they came back with relatively strong 9
comments.
One of them is that the two months period that we 10 originally allocated for them to do this planning of how they 11 are going to face it, it's not enough and they are asking for 12 four months instead of the two.
13 In connection with the 18 months, a comment was that 14 that was too short and they would like to have more time, but t
15 they didn't specify how much.
16 COMMISSIONER BERNTHAL:
It's just not clear to me 17 that it's a realistic time table and in a sense you're right, 18 you don't do a complete PRA for each plant, because you don't 19 reinvent the wheel and redo things that are generic.
But in 20 another sense, you do do a complete PRA for each plant, 21 because you take the generic part that's applicable, and then 22 you have got to consider the things that are site-specific, 23 and there are lots of those.
24 MR. STELLO:
Well, we struggled with those 25 questions, too, when we were discussing that schedule before
44 1
coming down here, and that's why I was so quick to answer, I 2
sorted-it out in my own mind.
If there's any sense that a 3
full scope PRA-be required at these: facilities, you just could 4
not do in that amount of time, because the expertise clearly 5
isn't available, and there aren't enough of them out there.
6 COMMISSIONER BERNTHAL:
You don't do it, you don't 7
need to do it, but you've got to do the stuff that's 8
non-generic.
9 MR. STELLO:
As you back off the about two years 10 from now reasonable, it probably is somewhat tight.
We 11 probably will have to relax a bit.
But I'd rather let that 12 happen as we unfold in the comment process and the case is 4
13 made for how much that is.
But I would rather hold with a 14 tighter schedule and try to get it done, rather than deciding 15 now we are going to loosen up.
I don't think it's impossible.
16 COMMISSIONER BERNTHAL:
I agree with you.
My l
17 concern is -- I don't want to interject too long here -- but 18 my concern is as I look at this program, I have the sense of 19 inching forward on a vast front, and if it turns out that 20 there simply are not the resources out there that -- saying 21 that if a utility could go out tomorrow and get the contractor 22 that it would like, and need more than 18 months, it is surely 23 realistic and it seems to me we surely should be receptive if 24 it requires more than 18 months.
But if many utilities want 25 to go out tomorrow and hire a contractor to assist in some of l
l
45 1
these areas, and they can't even come up with anybody for a l
2 year or two, then it seems to me that we ought to look at this 3-vast front that we're inching forward on and decide where we 4
are going to focus.
5 For example, BWR Mark I's, perhaps.
6 MR. ROSZTOCZY:
One of the contractors, at least, is 7
thinking along those lines, do them all together, that they 8
would contract with the owners' association and do, let's say, 9
all the Mark I's together.
So by looking at them, whatever 10 they learned in one plant they would be using it for the next 11 plant, and so on.
And they would save along these lines.
How 12 it works out, we will see.
13 MR. STELLO:
I would strongly, and have strongly, 14 encouraged the industry, however, to make sure that they have 15 within their own organizations sufficient expertise to really 16 get into this and rely on their contractors to help them.
I 17 think all the experience that I have seen in the utilities 18 that have done so, the rewards seem to be very great, having 19 that expertise --
20 COMMISSIONER BERNTHAL:
Sure, but you can't create 21 experts overnight.
22 MR. STELLO:
That's true, and that's why I say I 23 think we need to deal with that, because if someone came back 24 and said, "Well, we just hired, you know, these three or four 25 people that have that background, we think we'd like them to
e 46 1
have a more substantial role," I'd be much more inclined to
/
2 want.to give them much more time to do it that way, than just 3
purely contracting it out.
4 So I think that needs to be -- all those kinds of 5
things need to be sorted out, and we haven't done it yet.
But 6
it will evolve as part of the comment process.
7 COMMISSIONER ASSELSTINE:
Just one final comment.
I 8
agree with that, Vic, and I think Zoltan's point is well 9
taken, that if there is -- at least one of the principal 10 benefits that's like to come out of these reviews is much 11 greater understanding on the part of the plant staff that they 12 do it right, of their plant, understanding the systems and the 13 interactions -- that, at least to me, is one of the principal 14 benefits that's likely to come out of the probabilistic 15 reviews.
16 That's all I have.
17 CHAIRMAN ZECH:
Thank you.
18 Commissioner Bernthal?
19 COMMISSIONER BERNTHAL:
I have just one question, 20 and maybe a comment here.
21 Would somebody explain to me now how the GE 22 containment program that has, I guess, begun and somewhat in 23 earnest -- by the way, I should say that you are to be 24 commended for the fact that, as I understand it, you are on 25 sche ~dule with this program, so far at least, meeting the
4 47 l'
- schauule that the Commission has set.
I don't understand why 2~
it takes 18 months to get where we are, but you're on our 3
schedule, so congratulations.
4 The BWR Mark I program, if anything, is maybe a 5
little ahead of your schedule.
I applaud that as well.- But 6
how does this fit together?
There is an initiative on the 7
table for the Mark I containments.
Where does it fit?
8 MR. STELLO:
Well, originally it didn't.
It was 9
going on separate.
Now as part of the process -- I said 10 earlier -- directed that this get integrated into this kind of 11 process, it will not -- it's obviously ahead of schedule, 12 significantly in terms of the severe accident program by 13 itself.
But the issues that need to be dealt with, that are 14 going to be dealt with, will be dealt with as part of the 15 process before we bring it back to you, and I think the 16 schedule is around February.
So a couple of months, we will 17 be back here.
I 18 COMMISSIONER BERNTHAL:
Well, again, I would hope we 19 are,not bound by this vast front inching forward.
If we see 20 an area that needs attention, let's get at it and not -- and I 21 think that clearly is an area that, you know, you folks as 22 engineers have to assist us in.
But it seems to me at least 23 that's a smart PRA area where we can all be smart and get out 24 as quickly as possible.
25 Another question that touches, I think, on the next
.,.r
- - -.r--
-,-www---ww.
---v----,,.-,-,,,,,-y w-
,,---,-m.---,w--
,e,m.-,,-,,, -,, - -
48 i
1 presentation, we'll hear more about, how do you move ahead in 2
what you are proposing to do now, given that slide that we saw 3
a few minutes ago, that notes the number of the source 4
term-related issues?
How do you move ahead, given the fact 5
that there apparently are such large uncertainties yet 6
attached to so many of those issues?
7 We saw -- we were seeing bars, not even mean values, 8
but bars that spanned three orders of magnitude in some key 9
cases.
What do you do with that?
10 MR. STELLO:
That's the next presentation.
Would 11 you hold that question until --
12 COMMISSIONER BERNTHAL:
Okay, but I want to know how 13 then you guys are going to deal with that in the severe 14 accident implementation.
15 MR. STELLO:
Denny has this, and then you can go 16 back and answer that.
17 COMMISSIONER BERNTHAL:
All right, I'll defer that.
18 MR. SPEIS:
I usually do what my boss tells me.
19 CHAIRMAN ZECH:
That's usually a good idea.
20 Anything else, Fred?
21 COMMISSIONER BERNTHAL:
I think that's all.
22 CHAIRMAN ZECH:
Mr. Roberts?
23 Mr. Carr?
24 I think we should proceed with Dr. Ross, and 25 recommend that we try to keep on schedule.
We have other
~.
49 1
commitments this afternoon.
i 2
Please go ahead.
3 MR. ROSS:
Okay.
Whit I wanted to do was quickly go 4
through the tone and conten'. of the.SECY 86-369 that we sent 5
down to you, plan to resolve major areas of source term 6
uncertainty.
And why I want to come back to this issue of 7
uncertainty is it relates to what we talked about the last time, but there's been some additional considerations come up 8
9 since we sent you the paper.
10 Next slide.
4 11
[ Slide.]
12 I believe we showed a version of this last time.
13 This is a matrix of issues.
The left column is eight issues 14 from Appendix J of NUREG 1150 to be published, which maps 15 pretty closely to Table 6.1, which is the center column.
16 Now this center column is what provoked the paper.
17 When we discussed in July our final NUREG 0956 publication, 18 there was discussion from the Commission, in particular 19 Chairman Zech and Commissioner Bernthal, on the Table 6.1 of 20 that report, which had the areas of uncertainty, and there was 21 a proposal made which was accepted by the EDO on the spot that 22 we take these eight issues, try to get some independent review 23 from without the Research office or, indeed, from without the 24 Commission, to gather up a plan to resolve these issues at.d 25 come back to the Commission.
4 1
50 1
We have done this in part, but the right-hand column 2
is a consolidation where for administrative convenience we i
l 3
consolidated the topics into four broad topics which we see 4
there:
natural circulation, energetic events, core / concrete, 5
and fission products.
And we did note that we had recently 6
received a National Academy report that we had sponsored on 7
hydrogen, and we didn't need to send that back to the expert 8
review, but would rely on the NAS study.
i 9
Okay, next slide.
10 (Slide.]
11 The SECY 86-369 that we sent you is a long, more 12 than 50-page report.
In summary, what we have decided to do 13 is we have contracted with Brookhaven National Lab to manage 14 for us and to provide us their technical review and input, 15 these expert panels.
So they will provide the -- under 16 contract to us -- all of the technical work.
They will engage 17 the panels which have in fact now been engaged.
Each panel 18 has a chairman.
The members have been appointed by 19 Brookhaven, and the work of these four panels, as described in 20 the previous slide, starts next month.
21 COMMISSIONER BERNTHAL:
Denny, excuse me, but I hope 22 that it's made very clear in the charge to these review 23 groups -- it's implicit here, I guess, but somehow I don't see 24 a call for a firm recommendation on what needs to be done to 25 clear up the area of uncertainty -- a clear recommendation --
51 1
MR. ROSS:
That certainly is in the charge, and if 2
it is not as explicit, then we'll give them also the 3
transcript of this meeting, to make sure they understand.
4 That's the main area.
5 Now --
6 COMMISSIONER ASSELSTINE:
Denny, how are you 7
ensuring balance on those review panels?
3 MR. ROSS:
Well, I think the proof of the pudding is 9
just to look at the balance, which we'd be glad to provide, we lo have a list of it, that where we -- one way that you preserve 11 independence is to -- you lean largely on Brookhaven.
Now 12 what we have done is there's not any -- I believe it's true, I 13 don't believe there are any federal employees on this thing at 14 all.
We have several representatives from the United Kingdom 15 and from Germany, a very broad cross section in the research 16 establishment.
We do not have research contractors on the 17 panels in general.
I think in one or two cases there may be 18 somebody from Idaho, but it's not an area that he works in.
19 We are very proud of the chairmen of these four panels, and 20 indeed of the members.
I think if you looked at it, you'd 21 say, " Yep, that's a good bunch."
22 COMMISSIONER ASSELSTINE:
Okay.
If you'd send me 23 the list, that would be good; or send us the list.
24 MR. ROSS:
I'll send each of the Commissioners a l
25 list.
Surely.
m.
7
---r.
w
,y wm-,
52
, p 1
CHAIRMAN ZECH:
Good.
Thank you.
2 MR. STELLO:
For the record, this clearly meets 3
Federal Advisory Committee Act.
4 COMMISSIONER ASSELSTINE:
I'm glad to hear that.
5 MR. ROSS:
Which assurance we have in writing, and 6
if you don't have that, we'll provide that also.
7 CHAIRMAN ZECH:
That would be a good idea.
8 COMMISSIONER ASSELSTINE:
As long as you consulted 9
the appropriate people, that's fine.
10 MR. ROSS:
The OGC, Mr. Fitzgerald, signed it.
i 11 CHAIRMAN ZECH:
Proceed.
Thank you.
12 MR. ROSS:
The work of the panels is as shown here.
e 13 What we -- I'm going to show some charts in a minute, 14 additional uncertainty charts, but what we have decided to do i
15 since we sent you this paper just in the last few days, as we 16 are further deconvoluting some of the uncertainty analyses, we 17 thought we would add a fifth panel on the methodology of 18 uncertainty itself.
This is not a phenomena panel.
And 19 Brookhaven has agreed, and they are going to see what 20 probabilistic experts they can engage for this purpose.
21 There is a methodology in NUREG 1150, and we would 22 like to get an independent judgment on it.
23 The next page is just a summary of a table.
It's in 24 your report.
25 (Slide.]
l l
53 Now we expect when we come back in April to have 2
this Brookhaven report tell us what this table should be.
3 This is just an opinion that we have.
We're giving it to 4
these panels and saying we took a passthrough'in some of these 5
areas.
We have identified where, the way we understand money, 6
that we might get money in '87,
'88 and
'89.
Of course, 7
nobody knows what we'll get in '88 and
'89, so bhese are just 8
very approximate numbers.
And we tried to come up with some 9
unfunded requirements, but this is just a recommendation of a 10 very crude pass we made through.
We'll give it to the panels, 11 but we'd like to get this back from them, not necessarily in 12 dollars, but in work.
If they can identify additional work 13 they think is necessary to reduce uncertainty, we can cost it 14 out.
So we are really not asking the commission to take any 15 official notice of this table.
It's input to our panels.
16 COMMISSIONER BERNTHAL:
I'm sorry.
I'm, I guess, 17 thick today.
I don't understand what this means.
18 MR. ROSS2 The matrix is rows of phenomena and 19 columns of budget numbers.
Let's look at one example, the j
20 first row, natural circulation.
We had planned to spend $1 i
21 million in
'87.
We asked the Research staff what's the work i
22 that's unfunded, and how could you accelerate this work, if I
23 you had some more money, and we developed some time lines l
24 which are in the report, and we said give us this much more 25 money and we can accelerate the work.
I
=
54 1
However, you have to understand, this is our 2
recommendations.
What the Commission asked for is what 3
independent panels recommend, so we've got to redo this table 4
with the expert panels.
5 COMMISSIONER BERNTHAL:
Where does the budget end?
6 Do we have an overall recommendetion?
7 MR. ROSS:
Well, it's nothing more than the sum of 8
these rows or columns.
9 COMMISSIONER BERNTHAL:
They are all going to be 10 finished in '89; is that it?
11 MR. ROSS:
Oh, I would certainly not recommend that 12 we stop doing work in these areas at the end of '89 --
13 COMMISSIONER BERNTHAL:
I didn't think so.
14 MR. ROSS:
-- totally.
15 COMMISSIONER BERNTHAL:
When do they end?
Maybe we 16 ought to look at this.
17 MR. ROSS:
My planning horizon is never more than 18 five years, and I suspect in some of these areas, we'll still 19 be doing work in five years, and it may well be influenced by 20 work being done in other countries that would either 21 complement or confound the work.
Because other countries are 22 beginning to accelerate their work in these areas where we are 23 decelerating.
24 COMMISSIONER BERNTHAL:
Okay.
Again, I would hope 25 that these expert panels that you have convened -- and you
55 1
know, that, in my judgment, as you know", is exactly the right 2
thing to do -- that they would try, based on current knowledge 3
to give an estimate of the money that this agency needs for 4
its research to close these areas out, so there is a bound 5
there.
And we all understand new discoveries could be made
)
6 that may prolong matters, but --
7 MR. ROSS:
I understand.
8 CHAIRMAN ZECH:
Can you talk to the asterisk where 9
it says "does not include new work related to Chernobyl"?
10 Where is that going to be put?
11 MR. ROSS:
Well, we have asked each of these panels 12 to also, as they go through their work, if you uncover any 13 phenomena in that area that may indicate that more work needs 14 to be done because Chernobyl told you something in natural 15 circulation, or coremelt provision, identify that also.
16 CHAIRMAN ZECH:
Each panel has been told to do that?
17 MR. ROSS:
Yes.
Will be or has been.
18 CHAIRMAN ZECH:
All right.
19 Last page, the schedule.
You can see it's a short i
20 schedule, but most of our panel work will be done in January.
21 There will be some subsequent meetings in February.
22 Brookhaven firmly believes they can get in and get out, l
23 according to this schedule, so they have agreed to it.
24 Now there's a couple of charts on the area of 25 uncertainty that I wanted to show, and Ralph, if you will go
56
.1 to 'he back-up slide 12.
2
[ Slide.]
3 When we were here a couple of weeks ago, we showed 4
you some charts that Commissioner Bernthal was referring to as 5
rectangles.
I have some copies of the back-up charts, and 6
it's labeled No. 12.
We showed you rectangles such as shown 7
here, and this is for Surry, early containment failure 8
probability.
9 What we have done is several things:
10 First, we have replotted it on linear paper rather 11 than log paper, and what you see in your handout and on the 12 screen is on linear paper.
13 Second, each of these uncertainty calculations was a 1
14 result of 100 latin hypercube runs.
We have added on this 15 chart for illustration some little plusses that indicate each 16 plus is a run, and in some cases or many cases the plusses 17 overlap.
18 We thought if one was going to look at a rectangle 19 and envision the center of the rectangle as being the mean, 20 if that was a habit, at least you ought to see it on linear 21 paper.
Again, we are not advocating this.
22 Then we further deconvoluted this, and Ralph, if you 23 will go to 16, slide 16.
I wanted to show how you could take 24 this information and then get a little more out.
25 Unfortunately, you don't have this in your handout, although I
1 57 1
can make copies.
2 The ordinate of this scale is just number, number of i
3 runs, and the abscissa is failure probability.
Now it's the 4
same data, the same thing we showed you two weeks ago; nothing 5
has changed.
But what we show here is a predominant peak to 6
the left end of the scale, and only a few plusses, which has 7
direct containment heating, and very few triangles, which is 8
no direct containment heating.
Out to the right are high 9
probability.
This shows a pronounced peak at the low end.
10 One other thing, Ralph, if you will jump over to 11 slide 18, the last back-up.
12 (Slide.)
13 We took this same data and integrated it, and this 14 is the integral of the previous one, so you have the fraction 15 equal to a greater than X.
Again this shows the predominance 16 at the lower end.
17 Now we still have the same reservations about the 18 input to this whole thing, which is why we think it's a good 19 thing to ask Brookhaven.
Our biggest concern is -- well, two 20 concerns -- does the methodology make sense; and given that it 21 does, how do we display the data.
22 This is some different ways of displaying the same 23 data, and the ink is not very dry on these charts, so we are 24 still toying with it.
But this is what persuaded us we needed 25 a panel not described in 369.
~
58 1
COMMISSIONER BERNTHAL:
Let's go back to the 2
previous slide.
3 MR. ROSS:
Back to 16, Ralph.
4
[ Slide.]
5 COMMISSIONER BERNTHAL:
I don't understand what all 6
these different runs mean, and you've got --
7 MR. ROSS:
Well, there's two sets of data on here.
8 The plusses are when we assume that direct containment heating 9
works, which therefore increases the loads on the Surry 10 containment.
The ordinate is just numbers.
So if you look at 11 say 10 percent, you might see three runs -- three samples out 12 of a hundred gave me 10 percent conditional containment 13 failure probability.
So it's just a number of density.
And 14 if you look out say at, oh,
.81, it looks like there's a plus 15 there at 2, so maybe two runs out of a hundred occurred there.
16 COMMISSIONER BERNTHAL:
What's a run?
17 MR. ROSS:
We had 100 samples with a MONTE CARLO 18 like sampling of the containment failure probability.
In each l
19 case we sampled up to 25 issues of the distribution of 20 containment failure probability, containment loads, and so 21 on.
But we think if we work on it, we can get a more 22 informative display than what we showed you a couple of weeks i
l 23 ago.
That is what we are working on.
j 24 COMMISSIONER ASSELSTINE:
What would be the average 25 of all those runs?
L
59 1
MR. ROSS:
The median value -- if you'll let me --
2 Ralph, go to 17.
3
[ Slide.]
4 I can give you the median value.
If you go to the 5
ordinate of 50 percent, this is the one with direct 6
containment heating.
The median value looks like about 10 7
percent.
8 COMMISSIONER ASSELSTINE:
Okay.
9 MR. ROSS:
I don't know what the mean is.
10-MR. SPEIS:
.The mean is about.35 or something like 11 that.
12 COMMISSIONER ASSELSTINE:
Okay.
13 MR. ROSS:
And I think the one on slide 18, the mean 14 was way low.
But we haven't decided yet --
15 COMMISSIONER ASSELSTINE:
But the mean value is 35 16 percent?
i 17 MR. ROSS:
We haven't decided yet whether we want to i
18 represent the mean value.
Remember, this is a concern we have 19 over this whole sampling process.
This is wny we'd like to 20 get some more expert advice.
21 That's the end of my slides, Mr. Chairman.
22 MR. SPEIS:
The best estimate from this is probably 23 10 percent.
24 CHAIRMAN ZECH:
All right.
Thank you.
25 MR. STELLO:
The second part of that question was
. - - - - - _ - ~
60
)
1 now how are you going to use all this.
I think the answer is l
2 we clearly have got to wait until we get what we get from 3
these panels before we can really honestly answer the 4
question.
I don't want to be surprised thinking we're going to be able to deal.with it a certain way and then find that 5
6 when they're finished, they told us something we didn't know.
7 But you notice the schedule for getting that input back is 8
even before we'll probably be here with the Commission on the 9
, severe accident issue.
10 COMMISSIONER BERNTHAL:
Let me see if I have any 11 vague understanding of how you are getting these numbers. You 12 are doing a MONTE CARLO calculation, kind of a random walk or 13 something.
How many failure elements -- I assume that you've 14 got some number of failure elements or something then that 15 goes in here on the front end that are permitted to fail in a 16 random way, and that's how you and up with the output; right?
i 17 MR. ROSS:
Yes, sir, that's true.
18 COMMISSIONER BERNTHAL:
How many failure elements 19 are there?
20 MR. ROSS:
Just a minute.
1 21 There's a total -- it depends on the plant.
We've 22 only done Surry, and I think there were 25 issues that we i
23 sampled on Surry.
24 COMMISSIONER BERNTHAL:
Okay.
i 25 MR. ROSS:
For this -- for the issue we were talking 0
61 1
about, containment failure probability, there's two primary 2
issues.
One is what's the load, and the other one is what's 3
the containment response.
4 Now the chart that's he putting up shows both of 5
these.
6 (Slide.]
7 The darker thing is what we call the expert panel's 8
judgment on the load from direct containment heating.
It's a 9
typical probabilistical histogram so the sum of the dark 10 rectangles adds to one, and the abscissa is the expert's 11 weighted judgment on containment pressure.
12 For example, the second rectangle from the left is 13 about 65 pounds, and according to the expert panel, about say 14 32 percent of the time one would predict a containment load of 15 65 pounds.
16 A separate panel -- and this is the cross hatch to 17 the lighter shaped rectangles -- what's the approximate 18 distribution of the failure pressure.
Again, for Surry.
And 19 you can see four histogram bars, and again they add up to 100 20 percent, and this shifted to the right.
21 COMMISSIONER BERNTHAL:
Okay, so this is one --
22 MR. ROSS:
The MONTE CARLO would sample from one and 23 then the other and so on, and then you get -- for those 24 special cases where you had low light rectangles, low failure 25 pressure and high loads, you are going to get a high
62 e
1 containment failure probability, so you will get a cross at 2
one end, and conversely at the other end.
3 Now there's a lot of histograms like this.
This is 4
just --
5 COMMISSIONER BERNTHAL:
There are about 25 elements, 6
though, for failure modes.
7 MR. ROSS:
No, no, some of them are source term and 8
things.like that.
9 COMMISSIONER BERNTHAL:
Okay.
Okay.
25 elements, i
10 though --
11 MR. ROSS:
Of the uncertainty analysis -- remember, 12 we have high source term and low source term.
13 COMMISSIONER BERNTHAL:
Okay.
14 CHAIRMAN ZECH:
All right.
Any questions from my 15 fellow Commissioners?
16 Mr. Roberts?
17 COMMISSIONER ROBERTS:
No.
18 CHAIRMAN ZECH:
Mr. Asselstine?
19 COMMISSIONER ASSELSTINE:
No.
20 CHAIRMAN ZECH:
Mr. Bernthal?
21 COMMISSIONER BERNTHAL:
I guess I do have one 22 question, just schedulcr question, Denny.
Where do we stand 23 on NUREG 11507 Is that coming out in January?
24 MR. ROSS:
I asked yesterday, and it is going to the 25 printers in January.
Now I'm from Texas.
When the Texas 5
63
)
1 legislature has schedule binds, they unplug the electric 2
clock.
3 COMMISSIONER BERNTHAL:
We don't do that here, 4
unfortunately.
5
[ Laughter.]
6 COMMISSIONER BERNTHAL:
You're not that lucky.
7 MR. STELLO:
For NUREG l'150, we'd have to remove the 8
calendar.
9 CHAIRMAN ZECH:
Anything else?
10 COMMISSIONER BERNTHAL:
I think that's all.
11 CHAIRMAN ZECH:
Mr. Carr?
12 COMMISSIONER CARR:
I'm uncomfortable that we're 13 ever going to get through with any of this, when I read your 14 section on steam explosions, and you say extensive research 15 over the last 25 years has failed to produce a mechanistic 16 model of steam explosion process capable of accurate 17 quantitative prediction.
And then you say later on that 18 current knowledge is based on extensive international research 19 on thermal explosions in both LWR systems and LFMBR systems 20 over the last 25 years.
And then we've got another year where 21 we're going to spend -- you could spend a million bucks, and 22 then it goes on out in another year, and I don't get a warm 23 feeling we're ever going to get through with any of this.
Do 24 you?
25 MR. ROSS:
Well, yes, I do.
On steam explosions,
64 1
the acdeling is -- really, mostly what we have is in the 2
experimental area.
And it's not just nuclear.
Steam 3
explosions are a process problem.
4 COMMISSIONER CARR:
Yes, we've got more data on that 5
than we've got'anything else.
6 MR. ROSS:
Well, we don't model it very well.
The 7
general perception is it's a low probability, high risk 8
event.
We are spending, the way I measure money, a relatively 9
small amount of money to try to do a little bit better job.
10 But we had identified this as one of the areas that in a 11 significant budget cut, would probably be cut first.
j 12 So we think --
13 COMMISSIONER CARR:
So you're almost through with 14 this one, you think?
l 15 MR. ROSS:
I think that we're almost through, but I t
16
-- the problem is that we're victimized here by a rather wide 17 range of uncertainty, albeit low.
I think it's worth a bit 18 more time and money.
We had promised ourselves and therefore 19 the Commission a re-review of this subject in January of '87.
20 If you notice, in this paper we have identified one particular 21 test that we wanted to run, and then step back and take a i
22 look.
We haven't run that test yet.
Any additional money l
23 should be tilted more on the modeling end and less on the 1
24 experimental end, I think.
1 25 COMMISSIONER BERNTHAL:
Are you finished?
I did 4
i i
l
---~
65 1
remember that you promised me an answer to a question a while 2
back.
Did I get it?
Or maybe it slipped by me, if I did.
3 How are these uncertainties now going to fit into --
4 MR. SPEIS:
I think you asked the question how could 5
we have proceeded to resolve some of the issues from proposed 6
changes in uncertainties, and that's a very important 7
question.
That's why we have identified the areas that we 8
could proceed faster, they were the areas that uncertainties 9
did play such an important role.
10 For example, PWR containment spray additives, you 11 know the proposed -- we proposed deleting the requirement for 12 the chemicals during the spray injection period.
The 13 uncertainty there is the question of the form of iodine, which 14 is an uncertainty.
But we have found out from extensive 15 experiments that it doesn't make much difference whether you 16 have chemical or the water itself, it will be able to do the 17 job.
So we have to take an issue by itself and look at the 18 uncertainty and decide, you know, if what you know is enough 19 to proceed to make reasonable changes.
And that's how --
20 that's why we are proceeding this way.
That's why the 21 emergency planning reassessment which depends on this risk 22 baseline studies with all the uncertainties, you know, it's 23 going to wait some of these things before we proceed further.
24 But on separate issues like whether we give credit 25 for suppression pool decontamination, or whether we remove the
66 1
chemical sprays, we can look at the uncertainties and we can 2
say, you know, what does it mean.
3 COMMISSIONER BERNTHAL:
Well, I guess my only 4
comment and concern is that -- it's been said before at the 5
table here that in the end, I think we as a Commission are 6
forced to regulate to these uncertainties, to a large extent, 7
and you know, if you guys are trying to push forward with 8
proposed generic fixes and you've got two orders of magnit'ade 9
uncertainties in the numbers, that's not a very nice way to 10 have to make your case, because you leave a very wide latitude 11 for the industry to argue that you're wrong, the number really 12 is up here, and your uncertainty range not down where we might 13 think it is.
14 I'm also not quite sure how you handle cost-benefit 15 and the backfit rule under those circumstances.
And I'm r
16 afraid that what happens ultimately is that we get driven into 17 a very conservative position, and it's just a comment.
I 18 would like not to be driven to that position, frankly, and I 19 would hope that some of these source term issues can be 20 brought back with much smaller uncertainties in the next year 21 or two.
22 MR. STELLO:
I agree with you, and that's why I 23 answered earlier that we're going to hear what these panels 24 have to say in March, which when we revisit this question 25 again with the Commission, it will be probably some time after
e 67 1
March, that we will have at least that additional insight.
2 If things don't seem to get to where we can reduce 3
them any further, we're back where we regulate with very 4
conservative assessments, and that carries with it a penalty l
~\\
which may also mean safety.
It isn't necessarily clear that 5
'that is'the-best regulation or produces the safest --
6 7
' COMMISSIONER BERNTHAL:
That's right.
8
,MR. STELLO:
-- result.
And we will need to see t
9 what we get and go on that basis.
They are not going to be 10 any larger than they were last year, that's for sure.
11 COMMISSIONER BERNTHAL:
That's some comfort.
12 ddAIRMAN ZECH:
Mr. Carr, do you have anything else?
13 Well, let me thank the Staff for the briefing this 14 afternoon on both severe accident matters and source term.
15 Obviously we have more work to do.
I appreciate your schedule 16 being tight.
I agree that that's the way to make it, though.
17 But,spf course, it has to be done properly.
18 I think, too, we are dealing with uncertainties.
We 19 have talked about it before.
We are trying to get the 20 uncertainties down to where we can make decisions in some 21 degree of confidence that we are doing the right thing.
There 22 is a ways to go.
23 I think the panels that you have got certainly 24 should give us all some confidence that we have peer review 25 essentially going on in these areas that is very important.
68 1
I think we all want to get the uncertainties down as 2
far as we can.
We recognize we may come to the point whare we 3
simply don't get them down -- can't get them down any further, 4
at least at the time we figure without waiting a great deal of 5
months and years and maybe more, and then it will be up to us 6
to make a decision as to do we have enough confidence in what 7
we know at that time to make regulatory decisions.
And it 8
will be the Commission's responsibility to face that.
9 In the meantime, though, I do think we're moving in 10 the direction of assistance.
We are removing, I believe, some 11 of the uncertainties.
We are using a system of logic and 12 analysis that I think is going in the right direction.
It 13 seems to me we are making progress, and there will become a 14 time, of course, when we'll have to decide whether there's 15 enough progress to make regulatory decisions.
16 So I commend the Staff, and I would like to also 17 commend the industry for obviously the participation that they 18 have in this endeavor, and the panels, I think, should be 19 recognized for the contribution that they are making, too.
20 So, with that, I thank the Staff for a very 21 worthwhile and meaningful presentation.
The meeting is 22 adjourned.
23
[Whereupon, at 3:35 p.m.,
the proceedings were 24 adjourned.)
25
1 2
REPORTER'S CERTIFICATE
.. l 3
4 This is to certify that the attached events of a 5
meeting of the U.S. Nuclear Regulatory Commission entitled:
6 7
TITIZ OF MEETING: Briefing on Source Term and Severe Accident Matters (Public Meeting) 8 PLACE OF MEETING:
Washington, D.C.
9 DATE OF MEETING:
Wednesday, December 17, 1986 10 1-
' 11 were held as herein appears, and that this is the original 12 transcript thereof for the file of the commission taken
(~
13 stenographically by me, thereafter reduced to typewriting by 14 me or under the direction of the court reporting company, and 15 that the transcript is a true and accurate record of the 16 foregoing events.
17 e
18 Ann Riley 19 20 21 22 Ann Riley & Associates, Ltd.
23 24 25
. _ _ = _ -...
1 COMMISSION BRIEFING ON SEVERE ACCIDENTS AND SOURCE TERM DECEMBER 17, 1986 STATUS REPORT THEMIS P. SPEIS, NRR (x27517)
Z0LTAN R. ROSZTOCZY, NRR (x28016)
DENWOOD F. ROSS, RES (x37991) r l
1 w
w.,
r,
.r.-.. - -. ---,-.
-,,..-,-_..r
,.,---.,.-,_--m
--,-e----
--,.,ne
,-.m-
.---r, e
,n e.
9 0
AGENDA FOR COMMISSION PRIEF!NG ON DECEMBER 17 I.
OVERVIEW 0F THE SEVERE ACCIDENT AND SOURCE TERM IMPLEMENTATIOP PROGRAM II.
EXAMINATION OF EXISTING PLANTS FOR SEVERE ACCIDENT VULNERABILITIES
- III, STATUS REPORT ON THE OTHER TASKS IV, PLAN TO RESOLVE MAJOR AREAS OF UNCEPTAINTY IN NUREG-0956
I.
OVERVIEW 0F THE SEVERE ACCIDENT AND SOURCE TERM IMPLEMENTATION PROGRAM o
SEVERE ACCIDENT POLICY STATEMENT ACTION ITEMS o
IMPLEMENTATION PROGRAM o
RELATIONSHIP WITH OTHER PROGRAMS 4
- 4, l
SEVERE ACCIDENT POLICY STATEMENT - ACTION ITEMS l
]
POLICY STATEMENT NEW APPLICATIONS EXISTING PLANTS GUIDANCE ON THE ROLE SYSTEMATIC APPROACH OF PRAs FOR THE EXAMINATION OF INDIVIDUAL PLANTS PERFORMANCE CRITERIA IMPLEMENT MODIFICATION FOR CONTAINMENT THROUGH BACKFIT POLICY SYSTEMS CHANGES IN RULES AND REGULATORY PRACTICES, AS NEEDED 0
i i
Implementation Program Examination of Existing Use of New Source Term Plants for internal Initiators in Licensing Examination of Existing Guidance for Plants for External Initiators Future Applications t
)
Relationship with Other Programs Reference Plant Analyses IDCOR&NRC Understanding of Phenomena Generic Letter to Licensees Methodology for Plant Examination
.i IDCOR 4
Containment Implementation Guidance for Research & Analysis Program Future Plants l
PRA Studies i
and Guides Source Term Related Changes i
Source Term Research Regulatory Experience and Generic issues
II, EXAMINATION OF EXISTING PLANTS FOR SEVERE ACCIDENT VULNERABILITIES o
ACCOMPLISHMENTS o
GENERIC LETTER o
ACCEPTABLE METHODOLOGY o
GUIDELINES AND CRITERIA o
REFERENCE PLANT EVALUATION 4
o SCHEDULE
_. - - - ~, -, - -
ACCOMPLISHMENTS BOTH IDCOR AND NRC UPDATED AVAILABLE PRA STUDIES FOR FOUR o
REFERENCE PLANTS, NRC QUANTIFIED UNCERTAINTIES ASSOCIATED WITH THE RISK o
ASSESSMENTS, NRC AND IDCOR IDENTIFIED 18 TECHNICAL ISSUES OF CONCERN, o
16 0F THESE ISSUES HAVE BEEN RESOLVED, APPR0XIMATELY 20 IDCOR/NRC TECHNICAL EXCHANGE MEETINGS, o
IDCOR DEVELOPED METHODOLOGY FOR SYSTEMATIC PLANT o
EXAMINATION, NRC DEVELOPED GUIDELINES AND CRITERIA FOR THE PLANT o
EXAMINATIONS, NRC DRAFTED A GENERIC LETTER WHICH WILL INITIATE PLANT o
EXAMINATION, n
s GENERIC LETTER BASIS - SEVERE ACCIDENT POLICY STATEMENT
" COMMISSION PLANS TO FORMULATE AN INTEGRATED SYSTEMATIC APP AN EXAMINATION OF EACH NUCLEAR POWER PLANT NOW OPERATING OR UN CONSTRUCTION FOR POSSIBLE SIGNIFICANT RISK CONTRIBUTORS...F0LLO THE DEVELOPMENT OF SUCH AN APPROACH, AN ANALYSIS WILL BE MADE OF ANY PLANT THAT HAS NOT YET UNDERGONE AN APPROPRIATE EXAMINATION."
STAFF TO ISSUE LETTER TO EACH LICENSEE A.
REQUESTS A SYSTEMATIC EXAMINATION TO BE PERFORMED BY THE OWNER B.
SPECIFIES SCOPE OF EXAMINATION C.
IDENTIFIES ACCEPTABLE METHODS FOR THE EXAMINATION 1
D.
DEFINES DOCUMENTATION REQUIREMENTS E.
ESTABLISHES DISPOSITIONS FOR DISCOVERED VULNERABILITIES F.
SETS SCHEDULES STAFF WILL PRESENT LETTER TO COMMISSION (FEB, 87) PRIOR TO ISSUANCE TO LICENSEES l
ACCEPTABLE METHODOLOGY o
ACCEPTABLE METHODOLOGIES IDCOR INDIVIDUAL PLANT EVALUATION METHOD'(IPEM)
LEVEL II OR III PRA LEVEL I PRA WITH SOURCE TERM PART OF IPEM SIMPLIFIED (PHASE I) PRA WITH NRC APPROVAL OTHER SYSTEMATIC EVALUATION METHODS WITH NRC APPROVAL o-APPROVAL OF IDCOR IPEM DOCUMENTATION SUBMITTED FOR REVIEW TWO DAYS WORKSHOP TEST APPLICATIONS REVIEW COMMENTS ACRS REVIEW REVISED METHODOLOGY STAFF EVALUATION l
GUIDELINES AND CRITERIA 1.
SPECIFIC TO PLANT TYPES PLANT TYPE REFERENCE PLANT BWR/ MARK I PEACH BOTTOM BWR/ MARK II (LIMERICK, SHOREHAM)
BWR/ MARK III GRAND GULF PWR/LARGE DRY ZION PWR/ ICE CONDENSER SEQUOYAH 2.
BASED ON INSIGHTS FROM NRC AND IDCOR REFERENCE PLANT ANALYSES, PRAs, OTHER SYSTEMATIC ANALYSES, AND ASSOCIATED STUDIES 3.
PROVIDES A BALANCE BETWEEN ACCIDENT PREVENTION AND SEVERE ACCIDENT MITIGATION - SAFETY GOAL POLICY STATEMENT USED AS GUIDANCE 4.
ESTABLISHES A BENCHMARK FOR PLANT FEATURES WHICH ARE l
SIGNIFICANT TO SEVERE ACCIDENTS l
l e
1 REFERENCE PLANT EVALUATION PURPOSE:
PROVIDE HELP AND INSIGHTS FOR THE EXAMINATION OF INDIVIDUAL PLANTS i
o A SAMPLE EVALUATION o
INDICATES EXPECTED DEPTH OF SYSTEMATIC EXAMINATION o
DEMONSTRATES USE OF GUIDELINES 8 CRITERIA o
IDENTIFIES POTENTIAL SEVERE ACCIDENT VULNERABILITIES o
DISCUSSES P0TENTIAL CORRECTIVE ACTIONS o
PROVIDES A BENCHMARK FOR SIMILAR PLANTS t
-0 SCHEDULE o
PROPOSED GENERIC LETTER AND ATTACHMENTS DEC, 86 PREPARED BY o
CRGR AND ACRS REVIEWS COMPLETED BY FEB, 87 o
CC".SSION MEETING FEB, 87 o
GENERIC LETTERS ISSUED IN MARCH 87 o
EXAMINATION OF INDIVIDUAL PLANTS PLANTS WITH LEVEL II AND III PRAs, AND IPEM TEST APPLICATION PLANTS 6 TO 12 MONTHS REST OF THE PLANTS 12 TO 18 MONTHS
- III, STATUS REPORT ON THE IMPLEMENTATION PROGRAM DEVELOPMENT OF GUIDANCE FOR NEW PLANTS o
o CONTAINMENT PCRFORMANCE CRITERIA INTRODUCTION OF REALISTIC SOURCE TERMS INTO LICENSING o
o PWR CONTAINMENT SPRAY ADDITIVES BWR SUPPRESSION POOL DECONTAMINATION FACTORS o
o REVISIONS TO REG. GUIDES 1,3 AND 1.4 o
EMERGENCY PLANNING REASSESSMENT i
1 i
STATUS OF PLAN TO RESOLVE MAJOR AREAS OF SOURCE TERM UNCER1AINTY C0ft11S10N EETING DECEMEER 17,1986 Q
NUREG-1150 TECH. ISStlES NUREG-0956 MAJOR UNCERTAINTIES EXPERT REVIEW (APPENDIX J)
(TABLE 6.1)
(JULY 9 BRIEFING) 1.
CORE FELT PROGRESSION 1.
NATUPAL CIRCULATION IN y 1.
NATllRAL CIRCULATION, AND HYDROGEN GENERATION REACTOR COOLANT SYSTEM CORE MELT PROGRESSION, AFID HYDROGEN GENERATION
/
2.
NATURAL CIRCULATION IN THE 2.
CORE MELT PROGRESSION 2.
ENERGETIC EVENTS REACTOR COOLANT SYSTEM AND HYDROGEN GENERATION i
3.
HYDROGEN COMBUSTION 3.
STEAM EXPLOSIONS 3.
CORE-CONCRETE INTERACTI@
I
)
4.
HIGH-PRESSURE MELT EJECTION 4.
HIGH-PRESSURE MELT EJECTION 4
FISSION PRODUCT (DIRECT CONTAlt! MENT REVAPORIZATION AND HEATING) 10 DINE CHEMICAL FORM 5.
CORE CONCRETE INTERACTIONS 5.
CORE-CONCRETE INTERACTIONS A UTILIZE NAS REPORT:
/
TECHNICAL ASPECTS OF j
6.
STEAM EXPLOS10NS 6.
HYDROGEN COMBUSTION HYDROGEN CONTROL AND 1
COMBUSTION IN SEVERE 7.
FISSION PRODUCT 7.
IODINE CHEMICAL FORM LWR ACCIDENTS.
REVAPORIZATION 8.
10 DINE CHEMICAL FORM 8.
FISSION PRODUCT REVAPORIZATION r
I
BNL REVIEW 0F SOURCE TEPM UNCERTAINTY AREAS FOR EACH AREA IDENTIFIED, PROVIDE INDEPENDENT EXRRT REVIEWS AND TEGINICAL CONCLUSIONS ON:
t 4
STATE-OF-TIE ART STAFF'S DESCRIPTION OF EXTENT OF UNCERTAINTY CURRENT RESEARCH PLANS IIPLICATIONS OF OERNOBYL, IF ANY l
BNL REPORT ON TEGINICAL CONCLUSIONS FROM THE EXPERT REVIEWS a
1 w
s l
o SINARY OF BUDGETARY RECtJIREmfTS FY 87 FY 87 FY 88 FY 88 FY 89 AREA 0F UNCERTAltrrt FUNDED UNFut0ED FUf.'DED Ut!FLNDED FUTEED MATURAL CIRCULATICt1 1,000 400 1,000 900 1,000 CCRE FELT PROGRESSIct!
3,934 1,350 4,810 2,000 4,915 STEN 4 EXPLOSICt1S 567 260 425 375 425 HIGH PRESSURE MELT EJECTI0tt 1,700 200 1,800 250 1,500 CORE-CCNCRETE IttTERACTICtS 1,665 850 2,C00 0
2,200 HYDROGEttCOMBUSTICf!
579 530 600 200 0
IcDits'E CHEMICAL FCRt4 1,693 000 2,0c0 3C0 1,700 FISSICt: PRCrUCT EEVAFORIZATICt!
1a0 C00 200 700 100 SUBTOTAL 11,368 4,490 12,885 4,725 11,840 PROGRAM SUPPORT 4,3c8 300 4,350 0
4,350 TOTAL
- 15,726 4,790 17,235 4,725 16,190
'DCES t!0T INCLUDE IDI bCRK RELATED TO CHERNOBYL.
i l
S01EDULE S0llRCE TBN UNCERTAINTY RES0Liffl0N PLANS INITIAL RESOLUTION PLAN TO COPNISSION DECEFEER 1986 BNL REVIEWS BY EXPERTS JANUARY 1987 ADDITIONAL REVIEWS FEBRUARY 1987 BNL REPORT ON lE0lNICAL CONCLUSIONS FROM REVIEWS MARCH 1987 NRC STAFF CONSIDERS PEL REPORT Am SUBMITS FINAL RESOLLITION PLAN APRIL 1987 l
4
MWW6W9MfV&nW9Vf(fVIVftW6W6W6WGVstW((W@g(g(gVgygygygyggggggggggggg TRANSMITTAL TO:
Y Document Control Desk, 016 Phillips t
3 !
ADVANCED COPY TO:
The Public Document Rocm 3
j!
DATE:
l "L M $ Rfe 3 :
FROM:
SECY Correspondence & Records Branch 3
33:
Attached are copies of a Comission meeting transcript and related meeting 3
3 j j, document (s). They are being forwarded for entry on the Daily Accession List and 3 l placement in the Public Document Room. No other distribution is requested or required.
a3 Te c;w a M b e.v e.r e.
5 !
Meeting
Title:
I$ C le.8 k o ^
MS ccIde_.
M oN. ef C 3
12./W ff G Open V
Closed 3 !
Meeting Date:
3 :
3 !
3 :
3 :
3 l Item Description *:
Copies Advanced DCS 3 :
's to PDR Cg a
a :
S h
- 1. TRANSCRIPT 1
1 8!
n>l, Wa, n,k 3 :
3 ".
3 3:
S!
2.Se_w W % %
3
)
3 :
_3 :
b 3.
m 3 :,
4.
3 ll 3
3 l,l 3 :.
3 -:
5*
3::
7::
3 1
l 3
3[
3 :-
6.
335,:
3
- PDR is advanced one copy of each document, two of each SECY paper.
33 3
C&R Branch files the original transcript, with attachments, without SECY 3 :
$ lE papers.
3 3 a FL 3jpg
~
Y hht lY h 1 -.
_