ML20133K394
| ML20133K394 | |
| Person / Time | |
|---|---|
| Issue date: | 02/21/1985 |
| From: | NRC COMMISSION (OCM) |
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| ML20132C556 | List:
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| References | |
| FOIA-85-199, FOIA-85-A-15 NUDOCS 8508120220 | |
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PRESS CONFERENCE 2
3 THE NLERICAN PHYSICAL SOCIETY 4 AMERICAN PHYSICAL SOCIETY STUDY GROUP ON RADIONUCLIDE RELEASE FROM SEVERE 5 ACCIDENTS AT NUCLEAR POWER PLANTS 6
7 Room 1167 Nuclear Regulatory Commission 8
1717 H Street, N.W.
Washington, D.C.
9 Thursday, February 21, 1985 10 11 The press conference convened at 11:45 a.m.
12 PARTICIPANTS:
13' PROFESSOR RICHARD WILSON .
t Chairman
- American-Physical Society 14 Study Group on Radienuclide 15 Release from Severe Accidents at Nuclear Power Plants
! 16 WILLIAM HAVENS 17 Secretary American Nuclear Society 18 19 --
20 21 22 23 24 ActFederot Roooners, Inc.
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2 MR. HAVENS: I apologize for the confusion for this 3 press conference. I hope this microphone is operable -- I 4' can't tell -- is it? All right, then we will have to speak in 5 a lecturing voice.
6 THE PRESS: Will you talk into it anyway?
7 MR. HAVENS: It will sit there , I am not going to 81 be bothered by it, i
9 I am Bill Havens of the American Physical Society, 10 The American Physical Society thought this press conference 11, was being set up by the Nuclear Regulatory Commission staf f.
12 The Nuclear Regulatory Commission staff thought it was being l
13 7
set up'by the American Physical Society, and consequently .
14 nobody did adequate preparation to set it up. I found out on 15 Tuesday night that the NRC staff had expected the American 164 Physical Society to do it, and it was rather late then to take 17 into account the things that had to be done.
18 So, please, accept my apologies for the unfortunate 19 ppysical arrangements we have here.
20 A brief history of this report is that about two 21 years ago, the Nuclear Regulatory staff asked the American 22 Physical Society to undertake a study of the " source term,"
23 mainly to establish validity of the scientific base in the -
24 methods of calculation of some of the factors which were 4 Facoi n.,an.n. ine. ,
25 important in the " source term" used in serious accidents in
T l'
3 1! nuclear reactor plants.
2 We assembled a group of these phycisists, as Dick 3
Wilson said to the Commission in the previous meeting. I 4 called him up in Geneva in the summer of 1983 now to ask him 5
to be chairman of this group and he did -- I will confirm --
he did say, "Yes, but I'm sorry you made this telephone call."
~
6 7 He did agree to be the chairman of the group, and 8 we immediately began assembling a group to study this 9 particular report. There were a large number of people 10 suggested as members of the study group. We have a selection 11 process which has been published as to how this takes place, 12 and the study group was assembled in September of 19 83 when it 13 held its first. meeting at the Joseph Henrie Building of the 14 National Academy of Sciences. The group has been working 15 hard ever since.
16 Now, since Dick Wilson has been the one that has 17 been closest to the operation, I think it's best for him to 18 take 'over at this time.
19 MR. WILSON: Firstly, I would like to tell you 20 who of the group is actually here in case you want to ask them 21 some questions as well of, or instead of me.
22 Firstly, Dr. Araj, who has been the Executive 23 Director of the group who has been full-time working on this 24 and making sure I do the things I have to do at the right u n eral n.oon.r. inc.i 25l time, and trying to make sure all the things happen properly.
'l l 4 i
Dr. Allen, who is Chairman of the Chemistry Department 1h 2 at Brookhaven National Laboratories here; Peter Auer is not:
3l David Boulware is not. Fred Finleyson from Aerospace i
4 Corporation is here; Professor Simon Goren of the Department of 5 Chemical Engineering in Berkeley is here; Dr. Clark Ice, 6 Professor Leon Lidofsky, Dr. Mary Shoaf, and Dr. Irving Spiewak.
7 In addition, we have had a special consultant throughout much 8 of our study, Dr. Robert Bu.dnitz, and he was a member of the 9 study partially because at the time much of this work started 10 which we were reviewing, he was Director of Reactor Safety 11 Research and was commissioning part of the research. S o , i.e 12! was advising us on some of the background, and of course he 13 was also trying to find out for himself what he had done wrong.
-f 14 i (Laughter) 15 MR. WILSON: So , I don 't know how many of you heard 16 l the presentation of the Commission on the report, but let me 17 just summarize in a few brief words what we conclude. It's 18 , always hard to get a group of twelve physicists to conclude 19 anything, but we generally concluded there are a signi.jicant 20 number of -- pardon me, let me go back.
21 We have accepted what is now the general approach 22 for looking at reactor safety. That is an approach which 23 was brought up in Rasmusson's report in 1975, that if you try 24 ' to imagine what can go wrong in a scenario of events and then Ace Fedecol Reporters, Inc.
l 25 l try and follow that clue and first evaluate how probable it
1 1
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1 might be and second, a group of such events can be and, 1l 2! secondly, you evaluate what the final consequences are.
u We have been addressing the second of those ,
3) t 4 . evaluating what the final consequences are in some of those 5 accidents.
6 Now, in evaluating them, we have taken the group of 4
7 sequences which other people have evaluated. We have looked 8 at that just a little bit. We think they chose a sensible 9 set to look at, and we find in a number of those sequences 10 that was thought at one time to be quite a severe accident 11 was much less severe, was thought to be less severe now than 12 it used to be because of, finally, the containment vessel 13 which surrounds the reactor is less likely to fail than we 14 ! thought it was at the time of Rasmusson's report. That leaves 1
15 time for all sorts of things to happen such as deposition of 16 aerosols on the -- surfaces in the reactor so they will not 17 !. be released in the environment if and when a containment i
18 finally breaks.
I 19 On the other hand, again it 's very hard to get- a 20 group of physicists to make any sweeping generalization even 21 when they say there is conservation of energy then someone 22 comes out who say its a continued creation theory of the 23 f universe and if you look over a time scale cf terms of nine 24 I j years, even that doesn't work.
AcOFederal Reporters, Inc. ;
25 i So, likewise, we are unwilling to say that in all
p 6 It Ihcircumstancesthesourceterms, the amount of radioactivity, 2' will be less than what was predicted before in the reactor 3 safety study, and in fact there is some data which suggests I
4 under some circumstances it might be slightly more. There is 5 some more research still in progress to understand that 6 latter question and we believe that research should continue, 71 and we believe that the funding should be available to 8 continue both here and in the rest of the world.
9 Now, we did not address on those particular 10 circumstances how probable those things might be, we just
~ 11 addressed the consequences themselves. Now, I leave it I
12 open to ask any questions.
13 . MR. HAVENS: We will have questions from the 14 i a'udience. Yes?
I' t
15' -
QUESTION: If the source term doesn't get out of 16 the plant, how does that affect the environmental qualification 17 of equipment in the plant that would be used to mitigate an .
18 accident; have you looked at that?
19 MR. WILSON: We didn't look at it, but it's a 20 fairly general point that whereas if you inhale radioactivity
- 21) and get radioactive iodine in your thyroid, it can upset 1
22 what you are doing considerably. Radioactive iodine' deposited
,23 fonthecasingofanelectricmotordoesnotstopitworking.
24 MR. HAVENS: All right, is there another question?
An.F.4.coi n.oon.,t ine.
25 [ QUESTION: How much of the analysis is based on
. 7 ti il 1 f experiments er events like Three Mile Island, and how much 2' of this modeling is empirical?
3 MR. WILSON: Well, I think the first thing, Three di Mile Island had a very important indirect effect on the whole 5 process of understanding the source terms. But in detailed 6 analysis, it has no effect at all. And let me explain that.
7 Firstly, at the time of Three Mile Island , the 8 methodology of studying reactor safety, which goes back to 9 Rasmusson, was not generally accepted and used. That was a 10 tragic error because if it had been used, the differences 11' of Three Mile Island and the Rasmusson study would have been 12 understood and perhaps that accident could have been avoided.
13 ,
So, that was feature number one that happened,as 14 a result of Three Mile Island, people suddenly realized that 15i they had not been doing the job as well as they should have 16 I done.
17; Secondly, at Three Mile Island, that accident --
1 18! although it was most severe in some ways it has taken place --
f 19 very little radioactive iodine was released.
20 Now, the reason why radioactive iodine is dangerous 21; is because when you breathe it in, it tends to stay in the b
22 body; whereas if radioactive krypton and xenon, when you 23 breathe them in, you breathe them out again.
2d l At the same time it was found out that the Ac..F.d.,ai n. core ri. inc. I 25! radioactive iodine has a tendency to stay on surf aces and so on .
S jl!
I So, when it was noticed that not much radioactive 2]iodinewasreleasedanditwasnoticedbyallsortsofpeople 3 simultaneously, the question is , how general is that conclusion:
4 Would that apply to all sorts of other reactor accidents as 5 well?
6 And that started the line of research which leads 7 to our present review here today. If an accident happened 8 f airly similar to Three Mile Island when there is lots of 9 water still around and it is terminated, there is no question --
10 I don't think the committee discussed this -- but there is II not much doubt that the radioactive iodine will not be released I2 just as it wasn' t at Three Mile Island.
13
- Jiowever, we are talking here about accidents which I4I would progress to much more severe circumstances in Three l
15 Mile Island -- the hypothetical'in the sense that none haven 16 taken place, I hope it will remain hypothetical because other 17 people's calculations which we didn't review suggest they will 18 take place, if at all, only very rarely. They might probably I9 never take place in the next hundred-thousand years. So, they i
20 are by definition more severe than happened at Three Mile 2I Island.
22 And then the experience what happened at Three Mile l
23l Island doesn't directly apply to what we are discussing.
24 Speaking just as an individual, I wanted i QUESTION:
AcC> Federal Reporters. inc.l 25! you to respond to the question that Chairman Palladino asked, ,
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-1 I guess. On the basis of the information you have seen, do 2 ji you think the size of the evacuation zones should or can be l
3I changed at this point?
d! MR. WILSON: Well, I would like to -- the emergency 5 planning criteria of the NRC are based on a very large number 6 of issues. There have been various members of the committee l
7 who have been involved with that in various ways.
8 I would like to stress in answer to that, I think 9 almost everybody in the committee would like to stress 10 emergency planning -- and you mention evacuation zones.
I II! I think most members of the committee would agree --
l 12 though I haven't really polled them -- that that stress on 13 3 evacuation zone is a stress on the wrong thing. The ' stress l!
I d 'I we would depend on -- and I personally would not go beyond
. 15 ;. what was said to the committee , a report which I wrote for the I
16 i Governor or Massachusetts in 1980,'if an accident occurs, the 17 most important emergency planning criteria is to have someone 18 prepared and able promptly to measure if and when any radio-I9 active iodine is released and we would now add any radioactive 20 lanthanum is released.
2I And if people are not prepared to do that, they are 22 not prepared to decide whether or not an evacuation should 23 ltakeplace. So, my personal conviction is that evacuation is 24ll easy.
i I have seen two million people leave one scuare-mile Ac}Fooeral Reporters. 6ac.g 25' area in the City of London within one and-a-half hours , and I
i
a ' IC 1, that is done every day.
I 2' QUESTION: How? What 's the occasion?
3 MR. WILSON: You mostly walk to the nearest railroad d' station and catch -- there are a number of commuter trains 5 which are going out of there. The City of London has two 4
6 million people working in it, and a hundred-thousand people 7 spend the night there.
8 .
QUESTION: Have you ever ridden the Long Island 1
9 Expressway?
10 ' (Laughter)
Il MR. WILSON: Yes. I know the Long Island Expressway 12 is the longest parking lot in the world, but also having 13 b.een there af ter'a summer holi* day on a Sunday, it 's almost ,
14 stationary. But remember, go there at 2 o' clock on Monday 15- morning and the traffic is gone.
16 QUESTION: What was that second element that you 17 mentioned? You mentioned the two elements, two releases.
18 You mentioned radioactive iodine , and what was the second 19 ! one?
20 MR. WILSON: Well, lanthanum ' one particular 21 -element that's worth thinking about.
22 QUESTION: How do you spell that?
23 MR. WILSON: L -a -n -t -h -a -n - u -m .
24 MR. HAVENS: There is a question.
Ace. Federal Reporters. Inc.
25 l QUESTION: Dr. Wilson, I believe you told the NRC l
- 11 i
i 1
that you thought that those cource terms that you thought could 2 p be lowered or should be lowered were in the most probable d
3 accident sequences, but you also said the committee die focus 4 on probabilities.
5 MR. WILSON: Correct.
6 QUESTION: Could you specify the differences?
7 MR. WILSON: Well, there are people who as a group 8
have done a lot of study and a large amount of emphasis in 9 the last ten years since publication of the Reactor Safety 10 Study, the Rasmusson, has been on calculating going through 11 these various sequences, evaluating how probable the calculation s 12 are, how good these calculations are; how one can improve 13 reactors to make the probabilities smaller -- which is very 1
141 i'=portant, and there have been particular studies en this 15 question.
16 i The numbers of those studies, outputs of those h
17 ll studies , are available to us. 'We did not discuss the output 18 of those studies and do not want to say we believe in any 19' particular numbers stated by them.
20 " But, if we take the most probable sequences , for 21 example,' what these people say are the most probable things 22 to happen, we now look at the consequences, those are the 23 sequences. Some of those sequences are those for which we 24i ' think the consequences for release of radioactive iodine Aor.d.co a.oon.c . inc. l 25 !j in particular are going to be less than was previously assumed.
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1 Now, we are not saying that those calculations are 2 fright. On the other hanC. if you'll push me to the wall and i
3! say, could they be really way of f, we wouldn't say so either, d They think they are quite reasonable re-evaluations, though 5 we are not either endorsing them nor saying they are wrong.
6 QUESTION: Well, the bottom line is , do you think 7 they are safer then the study said ten years ago, the 7 ants1 8 are safer?
9 I MR. WILSON: I don't think we particularly want to 10 ask that question. But when Joseph Hendrie was Chairman of II I the Commission he did say that when he looked in the mirror 12 in the morning when he was shaving and failed to go to the 13 l telephone and. order the shut-down of every nuclear power plant 14l in the country, he was publicly declaring nuclear power plants lll 15 l are safe, e l I think no member -- I have not sent a telegram 16(!
il 17 !! to the Commission to ask them to shut down nuclear power plants l
18 ! or to propose any licensing. I don 't think any member of l!
19 the study group has either.
20' QUESTION: At the same time, is the bottom line that 21 you don't think that the current regulations -- there is not 22 enough research available at the moment to support changing 23 the current regulations?
2d f MR. WILSON: No, we don' t say that either. We l
Ac.4.oeror n.oonen. in. ,
25[explicitlydon't say that. We take no position on supporting i
13
- j II 1;l it because the Commission have a much bigger job in front of P
4 2 them than we address. The things wnich they consider when 3 addressing the regulations are the fact they've got a nuclear 4 power plant out there working, or a nuclear power plant out 1
5 ltherereadytoworkandsomeonescreamingthatifit doesn't 6 work, they will be wasting billions of dollars.
7 Those are issues which we did not address. You 8' can easily say, "Look, you can always wait to know the 9 answers." Well, you may wait forever. We don't address that 10 question. So, ,it could well be -- we say that we believe 11 that some more work could be done on the source term to make 12 the answers more reliable. The source term is one input into those questions.
, 13l .
14l We also made the statement to the Commission, " Don't 15 expect the source terms to become more reliable within three 16 l months,that' snot the time scale we are talking about."
17 There is talk about a time scale of two years to five years 18 when our report is going to be out. It will be published in 19 News Among Physics at the end of this year. It will be 20 read by physicists all over the world --
l 21 It will be digested, fdedback will come over a 22 period of two to five years. That is the time when more 23 detailed information is available. If the Nuclear Regulatory .
24 Commission feel they have to re-look at the regulations in a 4.-F.e.coineoon.n.w.]
25 i shorter time frame than that, well, they have to do so and i T
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ll tj to use whatever data is available to them, including what if 2 we have in this report.
3 OUESTION: Well, if you were on the Commission, 4l would you want those peer reviews completed in five years?
5 MR. HAVENS: Please, let somebody else have a 6 question. Right here?
7 QUESTION: Where, at this point, are the more 8 critical unknowns in. terms of possible major variances in 9 source term calculation?
10 MR. WILSON: Well, I think there are two primary 11 things. If you imagine a very severe accident, somewhat 12 toward the end of that accident progression you imagine a 13 molten core, melting through the reactor pressure vessel and 14 falling to the concrete floor.
15 It's quite obvious, the farther you get down the 16 l chain of events in the reactor, the more uncertain everything i
17 l gets. And in this particular thing that is the part of the 18 accident sequences which have been undertood least.
19 Now, we believe that it is possible to understand 20 it more than it is now understandable. It is certainly true 21 that in the world there are a lot of things you will never 22 understand, and we are not just recommending research for 23 research's sake. I mean, the standard recommendation of any 24 f scientists, "Give us another S500 million and we Ac.4.d.,ai neporieri. i inc.l, g roup o 25 will find some answers for you."
1 1: We are trying to be a little more specific than that.
2fWesay, "Some answers are available, we believe, in a finita 3 h period of -- the work will be over the two years ; the under-i standing of it will be over four, five years on those questions dl 5 and they would very much improve our knowledge."
6 And, of course, they might tell us that in some of l
7 f the operation and design features we are not doing the best I
8lpossiblething.
9I QUESTION: You said there were two things.
I 10 MR. WILSON: Oh, the other feature is that a lot of IIl the work is done on computed codes and computer calculations.
i Some I2 , Those computer codes have taken a long time to develep.
l 13,i of them in our view -- I mean, most of us on the study group, ,
a 14h several of us were professors, we have graduate students, il 15 h We have the task of understanding the computer codes our 16 graduate students have written without actually having to go 17-1 into. detail. And we demand that our graduate students give i
18 us a copy of the output.
19 We demand we want a Fest program. We demand all 20 sorts of different features -- that process has only just 21 begun -- to really make sure. that all the calculations are 22 doing what they think they are.
23 i
For example, one of the crucial computer codes only
'I think-l 24 became generally available in mid-November and we just Ac 9 .o.,eiit ooneri. inc.]
25 they have to be exercised and looked at by lots of pecple to a
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Ihmakesure, for example, that everybody understands what he is 2ldoing. It may well be that someone is using the computer code 3', in the wrong way and coming out with an answer which is f
4 inappropriate. You have to have a little bit of time follow 5 from that.
6 QUESTION: Could you describe, Professor Wilson, t
7 for us some of the types of research that you have in mind, do 8l they involve tests of the containment vessel, for example?
9 MR. WILSON: Well, I think we didn't discuss in 10 detail tes'ts of containment vessel. We believe those were 11 in progress. We had the report from people who test containmen<
12 vessels and we believed that should be looked at by the 13 Commission on.an on-going basis to be sure that every containment 14 vessel comes up to what the calculations are. There have 15 been one or two tests to destruction of one or two typical 16 containment vessels.
17 of course, what an individual containment vessel at 18 L Indian Point or Pilgrim Nuclear .' Wer Plant in Massachusetts --
f 191 which is one I am particularly interested in because it's about l
20 twenty miles away -- how that is strong, that of course has 21 to be carefully gone into.
22 And we are aware that there are quality assurance
- 23 programs but we haven',t discussed them.
24 The tests we are particularly concerned with on Acca .derai it. con.n. Wl 25 ?.he core cencrete interaction which are tests which are still
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1 in progress both in Karlsruhe, in Germany and in Sandia down 2ij in Albuquerque, in which they try and simulate the molten core h
3I falling onto the concrete and see what happens.
di The trouble is, the simulations are rather hard.
I I Some of-the crucial things about them haven't yet been measured S
6i and at the moment there is not complete agreement between the
, l 7 German results and the Sandia results though there have been Si explanations, possible explanations for this, and we think I
9 that should be just carried through to a more complete 10 conclusion.
11 QUESTION: Well, I can understand, where, you know, l
12' realizing that iodine is not a-stable gas, it seems to me 13 the crucial difference -- is what happens to the i,that .
14
-l containment itself. Is it going to remain intact?
15 MR. WILSON: That is the crucial difference that 16 everybody has called attention to.
17 I QUESTION: And one o'f the bi'g unknowns , still, is i 18 the core-concrete interaction, what happens if the core hits I
19- the concrete, 20 MR. WILSON: Yes. But it would not matter what 21 happens in the core-concrete interaction if the containment 22 still stays intact for a long period because what is released 23 in the core-concrete interaction, something is released even 24 though it may not be radioactive) will firstly be released into I ACMederal Reporters. lac.
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> 25 !l the containment vessel, and if that remains intact for a long i
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. that gives time for deposition of all the aerosols 21 which are produced and they will deposit out on all the 3 surfaces of the reactor. And that's one of the crucial things d of that time.
5 Now, we are not sure, the computer calculations 6 are still -- are the things that tell us what the detailed 4
7 amount of deposition and the detailed time scale. We are 8 not saying we completely trust the detailed numbers on that 9 yet, but we do know if containment lasts for an order of, 10 say, ten hours , that is a very important improvement in II reactor safety.
I2 MR. HAVENS: Yes?
13 Does that suggest that smaller containments QUESTION:
i Id I not be as safe as larger containments, PWRs or ice lmight 15' condensers?
16 The easiest to analyze and understand MR. WILSON:
I7 are the pressurized water reactors with large dry containments 18 because it is a static understanding.
I9' We are a little worried about the PWRs with ice 20 We are not saying they are wrong, we condenser containments.
21 are saying they are a little harder to understand because some 22 of the processes of the ice condenser have not been completely 23[ ll understood yet.
24 As far as the stress on the containment, that depends Aorw.,.in n.,. w.
25 And we sort of believe that happens on, is the steam taken out. t'
19 ll l'J1 over an adequate time scale. We are not completely -- we 3
2[ haven't looked at the question of the hydrogen will not be 3l taken out, there might be an explosive atmosphere inside --
t 4 I say it's not taken out by the ice condenser , it has to be 5l taken out by other devices of which there are other devices i
6 whose efficacy has to be looked at, which was not a question 7 for us to address and we didn' t address it carefully.
8 But the other issue is , it's quite conceivable 9 that the pressurized water with ice condensers aren't 10 better because the ice condenser might act to reduce -- in II itself be a filter for some of these fission products.
12 Unfortunately, there have been no tests on that i
13 on which we can test thi,s assumption, and that is a question.
14 i
One of our recommendations is that tests of'that sort 15 ;f proceed because that could make one believe that ice 16 f condenser containments , they might turn out to be even better i
17 than the others, we don't know.
18 QUESTION: One more thing on core-concrete inter-l9 reaction. Is there another answer on that than just the 20 China Syndrome?
2I MR. WILSON: The China Syndrome, remember, is the 22 melting of the core through the concrete base mat. I think l
i 23 l at the moment that's a question slightly in dispute. But it 1
24 '
depends what you mean by the China Syndrome.
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2Si Our new friends in China, at the time it was first
20 ll, 4
1; invented they weren't our friends. We can be reassured that i
2; at no time will the core -- everyone agrees the core will not 3 go that far down and that has been agreed for a long time.
4 So, the question, will it go through the base , the
'5 concrete base mat and get out into the earth below it, that is 6 still a matter of disagreement. Some people think it never 7 can, some people, it will.
8 There is one very important thing. The China 9 Syndrome has always been thought of, particularly in view of 10 a particular Hollywood movie , as being the worst that can 11 happen. I think a lot of people believe -- let me in fact 12 make a statement. It has comparatively modest effects on 13 immediate public health .
14 ' That is to say because if the material goes into 15 the earth which is an excellent filter for airborne radiol 16 activity which is the air surrounding it. We are much more 17 worried about the possibility of the containment breaking, 18 spreading into the air, rather than the core melting into the i
19' ground and then having an excellent filter from there to 20 the environment.
21 QUESTION: I thought the ANS source term study had 22 basically ruled out certain types of catastrophic explosions 23 as major initial rupturing agents #or the containment vessel.
24 Does your study also take that attitude?
Ac r.d...i n n.ri. w.
25 MR. WILSON: Well, there are two types of catastrophi c i
h 1
I !; things for rupture that have been suggested. One is a b
2 ' possible hydrogen explosion, hydrogen which comes from the 3 zirconium. We all know that hydrogen was produced in Three 4 Mile Island, and 'that came as a result of the hot steam inter-5 acting with zirconium in the fuel cladding. The zirconium 6 grabbing the oxygen and leaving the hydrogen free.
7 Now, that hydrogen then goes into the containment 8 vessel and can ignite, as it did about 1:30 on March 28, 1979, 9 and produce a pressure spike.
10 The question is, could that be dangerous enough, 11 big enough to break the reactor vessel. In dry containment, 12 I think it is generally accepted it will not because there 13 is eno* ugh steam around that would inhibit the exposu're --
14 although it might give a burn like happened at Three Mile 15 Island, it will not be complete enough to stress the 16 containment.
17 For the ice condenser containments it's a question 18 .of worry, and if there was no mitigation effect to take out 19 the hydrogen, that would leave an explosive atmosphere, then, 20 inside the containment vessel after such an accident.
21 However, there are such devices to take away the 22 hydrogen. We didn't evaluate their effectiveness but merely 23 accept it and so we don't make any particular state, ment on 24 that particular matter. We don't say the American Nuclear Ace-Fedecol Repoet, Inc.
25 Society is wrong, we just say we haven't looked at that
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a I,
I particular point.
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3 QUESTION: How do your. conclusions compare to the I.
4 q'lStone & Webster report of a year or so ago? It's about the h
5!fbest engineering firm and it came out with a study saying i
6 i that the threat of contamination from a nuclear accident 7 [l wasn't as great as everybody thought it was ,
i 8I MR. WILSON: Well, it's always easy to say the I
9 threat is not as great as everybody thought it was and 10, briefly define "everybody" first.
i.
(Laughter)
I1[
12 MR. WILSON: There are a very large number of people i
131 who thought at the time the Rasmusson's report came out,
.l 14 h there were two groups of people , one who thought reactors 15Ne were safe and the other who thought it was a fraud.
I 16j There were one or two people in the middle saying, Il 17 0 "It emphasites a very nice methodology for discussing reactor 18 h ! safety and making them safe, and operating them safely and
'l making them safer."
19 ]h 20 l I think I and most of the committee belong to that 21l third group'which wasn't very commonly introduced. So , we i
22 don' t normally discuss reactors are safer than we thought 23 ll they were. We do have the statement in there that for some l
2d ll of the sequences which are discussed by Rasmusson there was Ac>F.o...i n.,o, . .. en. 3, 25 t less radionuclide release than Rasmusson said, and we say that I
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,I 1f unequivocally in the statement, d
2; We do not go into detail on the probability of those 3 sequences. I think, though, we do refer to the people who 4, want to calculate such probabilities, we have repudiated them.
5 And of course, the total safety is a product of the prchability 6 in some sense it's a probability in the consequences.
7 QUESTION: Do the conclusions of your report have 8 any implications for changes in the regulations by the 9; Commission?
10 MR. WILSON: Indirectly, yes. And of course, it's 11 for them to decide exactly what because their regulations 12 are based on all sorts of things.
- 13 If I was to give you.a report on the number, the l ,
14 probability of severe automobile accidents of airplanes i
15' colliding with school buses in the State of Montana, that f
16l would clearly have a great impact on whether one should have 17 speed limits on school buses.
18 l However, it no one in setting the speed limit goes
,19 directly into those accident sequences in setting it since 20 one of the inputs to what he does is by no means the only
.21 input and it should not be the only input.
22 For example , if we said -- most of the regulations ,
23 in fact, are not based on any of this methodology at all, they are based on much older discussions. Maybe they should 1
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25i be. That's up to the Commission to decide, l
- * ;4 1[ MR. HAVENS: Are there any further questions?
QUESTION: Yes, I have one. I wanted to ask that 2 l1 3l one question, if you were on the Commission, before you started I
4l looking at the regulations, would you rather wait to see for i
5 the three to five years so peer revisw can come in, and 6 you publish this report, or would you feel confident, based 7 I on what you know about the source term research in the last 8 five years to say we can start taking a look at those things 9 now?
10 MR. WILSON: Well, when most people ask hypothetical 11' questions like that, the hypothetical thing is flattering, if 12 I was on the Commission. I just hope I 'm never going to be 13 on the Commission --
14 I (Laugh te r) 15 MR. WILSON: They have a set of decisions to 16 face which I just -- they have to cope with and they have to 17 cope with a set of committees up on the Hill which I hope not 18 to have to cope with. I'd just rather not address that 19' particular question.
20 MR. HAVENS: Well, if there are no further questions ,
21 thhnk you very much. We stand > adjourned.
22 (Whereupon, at 12:20 p.m., the press conference 23 was closed.)
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