Text

Transcript of 860513 Briefing in Washington,Dc Re Chernobyl Accident.Pp 1-64.Supporting Documentation Encl
	ML20197J088
Person / Time
Issue date:	05/13/1986
From:	; NRC COMMISSION (OCM)
To:	;
References
	REF-10CFR9.7 NUDOCS 8605190360
	Download: ML20197J088 (91)
	v • d • e

{{#Wiki_filter:_ _ _ _ _ _. ORIGINAL + *^Tu)' -~ 4.4 e.. 4 -W[,Q@lM.s l , s +.....

1 NU y,

x,,, n. % %. '.[ D n c. ,,.. : we, u.- e p"r py > ~r Der UNITED STATES OF AMERICA c ~'.) 'T NUCLEAR REGULATORY COMMISSION ..m . n. m: ..,4. 2; W.. g. -. w.g( ~* T f s 2 , 4. l,,. t .n -.s In the matter of: COMMISSION MEETING .c ,-,,.o..k< a: ,t.. Staff Briefing on' '.- 91 ~ l Chernobyl Accident . m.4, a, (Public Meeting) ~d*:d'*W d Occket No. , s -.x ( J s .. y e y ,, y,Y.y,,5)f1@g;;g;?y.j'g;p:gR nc.. ... X * % y ,si.L, s'1 'p.7, 7. w-3*.-;;m,.y ngJ g & f,;-(, v., 'a. c .g ;. C,.. s,.. .< m,,.., w e.: w..,. 1, %. m..,.,.., . e.1, .y w 2, w. n q4; no.. -.W.., ..,.s % x _ -... ~, l*. [,, , ;,,, ' g '. - .; 4.,. j .,. - c- .,,...; q,' e %..a4; 4 w. m,: y ig n,, f.., 9,%;j

e e

.s ; 4 j, T .m.6 ,g ,.t . y. c,j ;gg xg . p,,a. ..g:.....;r,y.. c _e s.. .,..e %. ,a . a . e.. ,...,,~~.m ~.

-. s pp<

J..,g m g,

acg._.g 3p g.,,v, e.r f u. g,,.y.

. m.. - o--,,...,. o ^..,,,..,

8 a

g j...p,d .,c... 31.' g g

m..,

m a, .T Location: Washington, D. C. 1 - 64 Date: Tuesday, May 13, 1986 Pages: . -. c. 2 m,'. .g ;:6 3nf 2 - r.:,. s.. > .t .e.,%g r .~.,. t . ~t.g 4 +.. .v Au- . n,; v. .j 2.. .a. .g. s,... %qt .y, s ANN RILEY & ASSOCIATES -g Court Reporters 8605190360 860513 1625 I St., N.W. ^ PDR 10CFR Suite 921 PT9.7 . PD$ . Washington, D.C. 20006 . o,,, e.)- . 3 '. ,,; q: *g... m., MMwed M&. eee ! a pe 4 O fh as

- T".

4.D -4 - - -8h4 OA'C

b 4
- - MO
4+'****

N -b

09

. a m' '-- ans

3 1 PROCEEDINGS .. ~ 2 CHAIRMAN PALLADINO: Good afternoon, ladies and 3 gentlemen. The subject of this afternoon's meeting is a staff 4 briefing on the Chernobyl accident and we need to vote to hold 5 this on less than one week's notice. May I have such a vote, 6 please, by the Commission? 7 (Chorus of unanimous ayes.) 8 CHAIRMAN PALLADINO: Following the Chernobyl 9 accident, the NRC established an incident tracking team 10 and members of this team will be briefing the Commission today l 11 on the facts as we know them now. Because of the Commission's 12 prior commitments, only one hour is available for the entire 13 Commission at this afternoon's meeting. I understand that 14 Commissioner Asselstine has to leave at four o' clock. I am' 15 informed by the staff that if we permit them to make the 16 presentation without interruption, they could do so in 35 17 minutes and I propose that we do that. Then we can ask l 18 questions and if it looks like it is going to go beyond 3:45, 4 19 Jim, I will give you a chance to ask any questions you may 20 have and we could continue. 21 I understand that copies of the briefing slides for 22 today's meeting are available on the table on the back of the 23 room. Do my fellow Commissioners have any additional remarks 24 at this time? 25 (No response.)

s. 4 1 CHAIRMAN PALLADINO: Thcn lct no turn the meeting 2 over to Mr. Stello, the EDO. 3 (SLIDE.) 4 MR. STELLO: Thank you, Mr. Chairman. We want to 5 tall you everything that we know and most important, I guess, 6 also those things that we don't know-about the accident. 7 Principally what we don't know relates to the details of the 8 design of the plant. 9 Since this is a plant of the type that is not 10 normally used outside of the Soviet Union, we have very 11 little actual design information on the plant and have had to 12 use pretty much a variety of sources, open literature, i 13 translations of documents and anything else we can get our 14 hands on to make the judgments as to what the facility really 15 looks like from a design point of view. 16 We do have quite a bit more information that we had 17 from various countries in terms of the consequences of the 18 accident and there we can speak a lot more authoritatively in 19 the sense that we have actual physical data that we can site 20 that has been measured and fr:m it make inferences about the 21 severity of the acciden'.. 22 What I propose to do today is to have first I 23 Mr. Denton describe the involvement of the NRC, that is the 24 staff itself, and then describe the interrelationship with NRC 25 and the interagency task force, as you know, that was a h

5 appointed to follow tho accidcnt and then wo will havo m2mbors 1 2 of the staff tell you as much as we know about the site and 3 the plant as well as the accident and its consequences and we 4 don't know the cause of the accident. 5 Let's get that up front so we can preclude a lot of 6 questions. Then, perhaps most importantly, the future plans 7 of how we intend to acquire additional information and what we 8 intend to do with that information as we get it. 9 With that, Harold, let me let you begin. 10 (SLIDE.) 11 MR. DENTON: This event was called to our attention 12 by the discovery of the Forsmark plant in Sweden when they [ 13 found high levels of radioactivity existing outside the plant 4 14 and you really need to give the Swedes credit for calling to 15 the world's attention that the accident had occurred. 16 Within a day or two, the Lee Thomas task force had 17 been formed. On the task force were all the principal' i 18 government agencies that you would expect to be involved in 19 this activity. We split up into various groups, some dealing 20 with the reactor, some with meteorology, some with health 21 effects and worked as a team. 22 Probably the last meeting of the task force will 23 occur tomorrow and I think at that time Lee expects to 24 dissolve the task force. Its principal purpose was to 25 ascertain the impact, the direct impact, on U.S. citizens so - -. - --..- -. - ~.-.

6 1 follow up actiona are com3 thing wa nScd to consider and we 2 will come back'to that at the end of the meeting. 3 I was at most of the task force meetings and Themis 4 was at some, Vic was at some. We would meet at least once a 5 day and put out press releases almost every day. 6 In order to coordinate what we provided to the task 7 force, we set up back here a tracking team. All three 8 individuals at the table, Brian Sheron, Themis and Frank 9 Congel were involved in that. In fact, we had ten or 12 10 people, technical staff, that have been involved essentially 11 full time since the event occurred and I did want to mention, 12 we got outstanding support from the people who run the 13 incident support center. 14 We had thousands of phone calls from both here and 15 abroad, a lot of information exchange going on and I think the 16 support center paid off handsomely in that case. 17 Brian will describe the site and the plant. Themis 18 will describe the accident and some of the radiological data 19 and then we will come at the end on what future plans and what 20 issues we might need to consider. 21 Brian. 22 MR. SHERON: Could I have slide three please? 23 (SLIDE.) 24 MR. SHERON: The Chernobyl site is a four unit site 25 located on the Pripyct River approximately ten miles northwest

7 1 of Chernobyl. Chernobyl is a small town located approximately 2 60 miles north of Kiev. The populations are shown there. The 3 terrain-is rolling hills. 4 There are four units of the RBMK-1000 Class plant at 5 the site. -Unit 1 was operational around'1981 and unit 4 was l 6 operational in 1983 and we understand that there are two more 7 reactors of that class under construction at the site. There 8 are approximately one dozen, I believe it is 14 is the latest 9 number we have, of this class units currently in operation in 10 the Soviet Union. 11 Next slide, please. 12 (SLIDE.) 1 13 MR. SHERON: This just shows you Kiev is in the 14 lower right corner, the Chernobyl site is approximately ten 15 miles northwest of the top of the Kiev reservoir, and the town 16 of Chernobyl is about maybe five miles northwest. 17 Next slide, please. 18 (SLIDE) 19 MR. SHERON: This is a brief description of the 20 plant characteristics. The RBMK-1000 plant design is 21 significantly different from commercial U.S. reactors. It is ] 22 a direct cycle boiling water pressure tube reactor. Each unit 23 is rated about 3200 megawatts thermal. The reactor fuel is 24 contained in a large number, something around 1700 individual 1 25 zircaloy pressure tubes that are in a matrix of graphite

g 1 blocks. 2 Each pressure tube contains about 18 zircaloy clad 3 UO2 fuel pins that are enriched about, I think the number 4 is, 2 percent to uranium 235. Of interest is that the reactor 5 is about 12 meters, or 40 feet, in diameter, and about 26 feet 6 high, which includes the top and side graphite reflectors. The 7 graphite matrix is enclosed in an inerted atmosphere. 8 (SLIDE) 9 MR. SHERON: I will skip the first four. These are 10 just more design facts. One thing it does do, they do have 11 on-line refueling, which is essentially a continuous process, l 12 and they do have emergency core cooling systems that are i a 13 designed for a primary coolant pipe break, but we are not sure 14 if that includes inside the reactor itself, and we understand 15 the plant has three diesels for the two units. I understand i i 16 these units are built in pairs so they can share equipment. 17 Next slide, please. 2 18 (SLIDE) 19 MR. SHERON: This is just a general view of a 20 similar plant. The pictures you have seen of the Chernobyl 21 site, the Chernobyl No. 4 would be to the left of the stack just under the number "7.". 22 23 Next slide, please. 24 (SLIDE) 25 MR. SHERON: This is a cross-sectional view of the l . _ _..., _. _... _ _ _. _ _ _ ~. _ _ )

9 1 main building, and this is not Chernobyl but a similar plant. a 2 As you can see, the turbine hall is to the left and it has i L 3 four steam drums. As you can see, the refueling handling 4 machine is directly above the core, and there are eight 5 reactor coolant pumps, six of which are used continuously, two 6 of which are on standby. 7 The plant does have a suppression pool. Actually 8 there are two of them, which are down in the bottom below the j 9 core. I i 10 Could I have the next slide, please. 11 (SLIDE) i 12 COMMISSIONER BERNTHAL: You might slow down just a 13 little bit. I'm losing this blinding pace here. 14 MR. SHERON: I'm sorry. 15 COMMISSIONER BERNTHAL: Do we know where the spent i 16 fuel pool is on that drawing? Do we have any idea? 17 MR. DENTON: I think it's on the same floor as the 18 refueling level, and I have seen pictures where it is on that 19 same level and is sort of behind the pool. I may have a 20 Vu-graph that might show that. It is on the same level as the 21 refueling level, and the refueling machine moves back, it 22 appears, 50 feet or so and there is the pool. 23 COMMISSIONER BERNTHAL: Essentially between Units 3 24 and 4, I would assume. Is there a common spent fuel pool, do 25 you know? -...,--.n n-n,,~.-.---- -+,---- c- -,,..,-n..-c.+.- ,-nn

10 1 MR. DENTON: I don't think it is a common spent fuel 2 pool. My understanding is that the systems that are common -j 3 are the control room -- neither unit depends on the other, but 4 there are some interchangeable units, so I think each has its 5 own spent fuel pool. 6 CHAIRMAN PALLADINO: Why don't we continue until 7 they get up the slides. 8 (SLIDE) 9 MR. DENTON: That shows the floor of the reactor 10 building. These are concrete shielding blocks, and you see the 11 refueling machine, and I presume the refueling pool is off to 12 the left. 13 MR. STELLO: I visited a unit like this, and as I 14 recall, I believe each unit has its own pool, and I believe 15 they were up to double stacking at the time that I was there. 16 CHAIRMAN PALLADINO:- For now, we don't know for sure 17 whether they share a common pool. 18 MR. DENTON: I'm pretty sure they don't, but we will 19 check on that and get back to you. 20 COMMISSIONER BERNTHAL: It is not critical. 21 CHAIRMAN PALLADINO: Okay. Why don't we try to go 22 on. 23 MR. SHERON: I think we are at Slide No. 9. This is 24 a sectional view of the reactor building. Again, you can see 25 the components that I just pointed out, the reactor coolant

11 ^ 1 pumps, eteam drums, tho rofuoling deck. '( 2 Could I have the next slide, please? + 3 MR. DENTON: Come back one. Commissioner, Item 14 4 is labeled the cooling pond, which is the cooling pool, 5 obviously, next to the machine. 6 MR. SHERON: Could I have slide number 10, please. 7 (SLIDE) 8 MR. SHERON: This is a photograph of the top section 9 of the reactor. As you can see, the T joints where the 10 pressure tubes bend and-go up to the steam drums. 11 Could I have Slide 11, please? 12 CHAIRMAN PALLADINO: Wait a minute. Tell me more. j, 13 Which ones? These off to the right and the left? 14 MR. SHERON: These are stainless steel channel 15 risers. The very bottom of the tube is the top of the active 16 core region, and so the man in this picture is standing on top 17 of the actual charcoal block, and these come up to meet and 18 mate with the refueling machine, so you can tell they are 19 about two floors high, and these are stainless steel 20 tubes. And off to the left are the steam collection tubes. 21 COMMISSIONER BERNTHAL: Can you go back to the 22 schematic diagram, then, and would you mind just walking 23 through this? 24 MR. SHERON: Would you put up Slide 9? 25 COMMISSIONER BERNTHAL: I guess what I want to see I

12 1 is you walk through the heat flow out of the core. 2 CHAIRMAN PALLADINO: Why don't you stand up, Brian, 3 and do it. It might be a little easier for you, if you will 4 just point to the picture and walk through it up there. 5 (SLIDE) 6 COMMISSIONER BERNTHAL: It would be helpful to me if 7 you start with the core and trace the heat flow out of the 8 Core. 9 MR..SHERON: This doesn't show the T joints, but 10 this is the core. Cooling comes up through the pressure 11 tubes. There are T's all along each pressure tube. Steam flow, 12 the steam and water mixture, goes over here, up into these 13 headers, the steam drums. It is separated,, steam comes out, 14 goes off into the turbine, water comes down through downcomers 15 into these collection headers, back down through the pumps, 16 from the pumps goes up in through this header here, through 17 these miniheaders, or subheaders, as they call them, through 18 individual pressure tubes, now penetrates through this 19 boundary -- this is not a sealed boundary, I don't believe -- 4 20 back up in through the core. 21 COMMISSIONER ZECH: Where it is heated and boils and 22 turns to steam and starts all over again. 23 MR. SHERON: Yes. I believe the exit quality'is 24 about 14 percent coming out of the core here. 25 COMMISSIONER BERNTHAL: Now, where in that diagram,

_ ~ -. - 13 1-at what points -- you said that the entrance back into the 2 bottom of the core there are not sealed entrances. Where in 3 that diagram is there access to the building itself should 4 there be a rupture of any kind? Do you understand what I'm 5 saying? 6 MR. SHERON: Yes. I don't know. This is about the 7 best drawing we have. I imagine there are access points 8 throughout here. 9 COMMISSIONER BERNTHAL: No, I don't mean human 10 access. I mean at what point, if there is a rupture, is there 11 no containment or physical barrier? 12 MR. DENTON: We will get to that. 13 [ CHAIRMAN PALLADINO: Why don't we wait till at least 14 we have that much background. 15 COMMISSIONER BERNTHAL: Fine. 16 MR. SHERON: May I have Slide 11, please. 17 (SLIDE) 18 MR. SHERON: This, again, is just a picture of the 19 top of the reactor on the refueling deck. Could I have Slide 20 12? 21 (SLIDE) 22 MR. SHERON: This is just a flow diagram which shows 23 what I just described, the flow diagram through the core into 24 the steam drums through a feedwater header into the main 25 circulating pump and then back into the reactor.

14 .s. 1 CHAIRMAN PALLADINO: Is this an accurate 2 representation of where valves are? Are there valves at the 3 top of these pressure tubes or at the bottom of the pressure 4 tubes or anywhere -- 1 5 MR. SHERON: My understanding is that the only 6 valves that are on the pressure tubes are on the discharge 7 side below the steam drums, and they are not shown on this 8 diagram. But when they refuel, it is refueled with coolant 9 going through that pressure tube. It's not valved out. 10 MR. DENTON: I think in general, Mr. Chairman, the i 11 more information that we get, the more complicated the system i 12 becomes. We are working from textbooks and then we get better 13 and better technical journals that show more and more detail. l 14 CHAIRMAN PALLADINO: But there is on the line, this I 15 horizontal coming off the pressure tubes through the core, you 4 16 say there is a valve on each one of these connecting pipes to 17 the steam drum? 18 MR. SHERON: Yes. According to the literature, i 19 there is a valve there, 20 CHAIRMAN PALLADINO: A remotely-operated valve? 21 MR. SHERON: To my understanding, it's with a long 22 extension which they remotely operate. 23 CHAIRMAN PALLADINO: All right. o 24 MR. DENTON: There is some uncertainty among us as 25 to where it really is, but we could ask the staff who may 1 ,,_,,,-,,,.,,,.r,.. ..,,,c.., f._.-._ym_ _.,,._.-y.,._.

15 I 1 know. We have been trying to read through the various p. 2 journals, and some people may know more than those of us here. 3 MR. STELLO: Let me try to answer your question. l 4 The best understanding that we had -- and that changes, so it l 5 may be different again -- is there is a check valve someplace 6 in the discharge line up near the steam drum. There is a 9 7 control valve, as I understand it, on each of the discharge 8 lines liquid to control the amount of flow in each of the 9 tubes and balance it. So on the bottom, a control valve on j 10 each of the tubes. t 11 CHAIRMAN PALLADINO: You say there is a bottom valve 12 on each of the lines? 13 MR. STELLO: A control valve. 14 CHAIRMAN PALLADINO: A control valve. 15 MR. STELLO: For each one of the 1700 tubes. Is 16 that right, Warren? 17 MR. SWENSON: Right, coming off the distribution 18 header. j 19 CHAIRMAN PALLADINO: And the at the top, is there a 20 valve or a check valve? 21 MR. STELLO: A check valve. l 22 CHAIRMAN PALLADINO: All right. Sorry about the i 23 interruption. Go ahead. 24 MR. SHERON: May I have Slide No. 13, please. 25 (SLIDE) 1

16 1 MR. SHERON: Let me just start out by saying that 2 the primary system does not have a housing -- and I will call 3 it a housing, not a containment -- equivalent to a 4 Western-style. containment. 5 CHAIRMAN PALLADINO: Who calls it a housing? We do, 6 or they do? 7 MR. SHERON: We do. It does enclose the reactor 8 and major piping within two drywells and provides a watwell 9 beneath the drywell structures. The remaining primary system 10 is in what we would call a confinement structure, and the 11 cells which it is in are metal-lined rectangular volumes. 12 Based on all of our reviews to date of the ( 13 information we have, we don't have enough information to draw \\ 14 any definite conclusions on the primary system ~ enclosure 15 capability. We just don't have enough. What is apparent, 16 though, is that their design philosophy is very different from 17 ours. l 18 Could I have the next slide, please. 19 CHAIRMAN PALLADINO: Do you have any comment as to 20 what extent they are different? 21 MR. DENTON: We are going to come to that. 22 (SLIDE) 23 MR. SHERON: This shows our best judgment of where 24 these enclosures are. There is a reactor enclosure. It is not 25 highlighted here. The reactor and the graphite have a metal

17 1 container. 2 CHAIRMAN PALLADINO: And the metal container is that 3 heavy line? 4 MR. SHERON: That line right there, yes. That is a 5 bellows arrangement which we think seals the graphite from any 6 ingress of steam. In that area in between, we understand it 7' is nitrogen filled and there is a water-filled biological 8 shield in that region. 9 CHAIRMAN PALLADINO: What region? Point to it j 10 again. 1 11 MR. SHERON: Right in there (indicating). Between 12 there and the heavy line. Right in there. It is nitrogen r ( 13 filled and with a biological shield. 14 The compartment which is right outside the core, 7 which Themis is outlining now, we think that that has a design 15 1 16 pressure of 27 psi. 17 COMMISSIONER BERNTHAL: Is that psia or gauge 18 pressure, or what is it? 19 MR. SHERON: I think it's gauge. 20 CHAIRMAN PALLADINO: Which direction, outward or 21 inward? 4 22 COMMISSIONER BERNTHAL: We don't know for sure. 23 MR. SHERON: We don't know for sure. 24 MR. STELLO: It is quoted as a. differential 1 25 pressure, which would lead you to believe it's a gauge l i

18 1 pressure. 2 MR. SHERON: The outer volume, which includes the 3 suppression pool and where the primary system coolant piping 4 is, we understand has a design pressure of 52 psi gauge. 5 CHAIRMAN PALLADINO: This is where I have a 6 problem. If it's 52 in there, then assuming that there is no 7 overpressure in that intermediate part, it has to be able to 8 take 52 across there, doesn't it? That line there 9 (indicating). 10 MR. SHERON: Yes, which would lead one to think that ) 11 may be 27 pounds in an outward direction, or it may be 27 12 pounds to prevent the ingress of air to the reactor cavity 6 J 13

area, t

14 CHAIRMAN PALLADINO: But what I am getting at is if 15 the intermediate region gets down to atmospheric pressure, 16 then is this containment or this housing good for 52 psi 17 across there? j 18 MR. STELLO: That is what the literature suggests. i 19 CHAIRMAN PALLADINO: I see. 20 MR. DENTON: I might mention that Units 1 and 2 21 don't have a containment such as this. In fact, the first 22 reactor model like this went into operation in '73, and it 23 didn't have any of the lower level containment. The 24 literature refers to boxes, and it appears that they tried to i 25 design a system whereby they could cope with a break in a

~ 19 1 large line without overpressuring certain compartments. 2 I think the key in this slide is that the reactor 3 core area itself appears to be external to the containment. 4 CHAIRMAN PALLADINO: Looking at the reactor vault, 1 5 you say there is a bellows in the vertical part around the 6 reactor vault. Is that able to take the -- what did you say 7 the pressure was in that intermediate, 27 psi? Does that mean 8 that the reactor vault could take 27 psi across it with the 9 bellows? 10 MR. SHERON: We don't know it. 11 CHAIRMAN PALLADINO: Okay. 12 MR. STELLO: Themis, why don't you point to the 13 liner that's around the vault, around the core. It appears 14 that there is a liner all around the graphite, for which at l 15 least you would think they made an effort to put some sort of j 16 a seal that would prevent any oxidation of the graphite either i: 17 by air, oxygen, or more importantly, perhaps, is to make sure 18 you don't get any moisture, any water in there because, as you i f 19 remember in some of the early pictures, if that graphite were 20 in any way disturbed with oxidation or moisture, it would be 21 an enormous task to replace the graphite in the core region. 22 So I think that they must have taken the precautions 23 and they are a'll inert gas filled to preclude and I'm sure l 24 they must take measures to prevent moisture in the gas to 25 avoid a problem with the graphite.

c. 20 1 MR. DENTON: I checked out our interpretation, ,m 2 Mr. Chairman, with some of our colleagues at the NEA meeting 3 Friday, and I think their view is about the same as ours, 4 that it does have this inner containment that blows down to 5 the suppression pool in the event of a pipe break but the 6 containment does not include the reactor core area. 7 There are a lot of detail questions about it that we 8 don't have access to yet, and it might be some time before we 9 do, but clearly, the core sits there, and the top of the 10 building above it is a standard industrial-type building that 11 you saw in the photographs. 12 COMMISSIONER BERNTHAL: And yet there is a -- I / 13 l better ask it as a question here. The black line across the 1 14 top of the core area there, that represents the 27 psi area, 15 does it not? 16 MR. DENTON: We don't know that. 17 CHAIRMAN PALLADINO: That would have to be quite a 18 structure to be able to take 27 psi. i 19 MR. DENTON: You saw in the previous photograph 20 where they were standing on top of the reactor core, and all 21 those 1600 or 2000 tubes penetrating it. It may have some l 22 sort of a gas seal, but I just don't see that that is designed 23 as a pressure-tight containment. 24 COMMISSIONER BERNTHAL: Let me ask the question, if 25 I may, this way. i

21 a e.. 1 MR. DENTON: The containment that exists that we 2 know about is over in the corner, and the literature is very 3 clear it is designed in the corner so a pipe break blows down 4 through those openings and bubbles in the water, and they call 5 it a bubble condenser system or something like that. So that 6 is what the literature focuses on mainly, and it is pretty 7 quiet on what there is around the core. 8 COMMISSIONER BERNTHAL: It is designed to make sure 1 9 that in the large pipe break, the heat gets dumped in the 10 suppression pool. 11 MR. SHERON: Yes. 12 COMMISSIONER BERNTHAL: But they clearly went to a j( 13 good deal of effort and trouble between this design and l 14 earlier designs, I gather, in installing the suppression pools i 15 and whatnot. Can you speculate on what the philosophy would 16 be, then, that would still leave the core if, as you suggest, 17 with fairly straightforward access to the building? 18 CHAIRMAN PALLADINO: Let me suggest that you keep 19 that till after 3:45. 20 COMMISSIONER BERNTHAL: As long as you write it 21 down. 22 CHAIRMAN PALLADINO: One of you write it down. 23 MR. STELLO: I will. Mr. Chairman, we are almost 24 finished, if we could have a few more of those uninterrupted I 25 minutes. 4 i i I

~

7 1 CHAIRMAN PALLADINO: You can slow down a little bit 2. in your speaking speed because my hearing speed is not equal 3 to your speaking speed. 4 COMMISSIONER BERNTHAL: Mine either. 5 MR. SHERON: Next slide. 6 (SLIDE) 7 MR. SHERON: This next slide just show5 a very 8 simplified diagram, with our understanding of these l 9 compartments and the relative elevations as well as some other 10 dimensions. 11 Could I have the next slide, please? 12 CHAIRMAN PALLADINO: I understand there are some 13 [ check valves in some of those liners, also, but we will come 14 back on that. 15 MR. SHERON: Yes, sir. There are check valve's which 16 connect. 17 Next slide. 18 (SLIDE) 19 MR. SHERON: The next one shows just the suppression 20 pool arrangement. It is concentric pipes. The steam would go 21 to both suppression pools. It's one on top of another. And 22 one last piece of information is that the reactor does sit on 23 a concrete pedestal above the suppression pools. 24 Next Slide. 25 (SLIDE)

I 23 l' MR.'SPEIS: I will take over now, Mr. Chairman. I 2 will start by describing the event. Basically, on April 26th 3 at approximately 1:23 a.m.,-explosions. occurred at the 4 Chernobyl Nuclear Power Plant in the Soviet Union. 5 CHAIRMAN PALLADINO: You have an "s" on there. Is 6 that right? I 7 MR. SPEIS: We have heard things from newspapers or 8 other sources that there possibly could be more than one j 9 explosion. It is speculation. That is the reason I have an I -10 "s" there. l 11 The explosion is said to have taken place in the 12 building which houses the reactor, but we don't know exactly 2 13 what part of the building or what part of the reactor. It is 14 reported that the reactor had been previously operating at 7 15 percent of power. As we have said, the cause and location of i j 16 the explosion or explosions is not known. The explosions led 17 to failure of the primary system boundary, radioactive release 18 and subsequent graphite fire. 19 Decay heat plus heat from the graphite fire produced 20 temperatures sufficient to melt the fuel. We are talking 1 21 about fuel melt temperatures of 2500 degrees C., and the 22 graphite ignition temperature has been reported to be anywhere 23 between 600 degrees C. and 3600 degrees C., and that depends o 24 the type of conditions that are available, whether you have 25 air, how much oxygen and things of that sort, and how much s y .v.-.-, --y .,,y, r... ,.3..w_,__.p., ,._,..wm.y.r-,- _-,._,--m-,._, .w_,w,.-+..,,,

24

s' 1

heat is also available.. 2 . COMMISSIONER BERNTRAL: Themis, on the explosions, 3 is there any confirmation or do you have a. view on the 4 question of whether the initial explosion was, as I have heard 5 it reported, a " steam" explosion, not in the sense we are used 6 to talking about, I would assume in the sense of a boiler 7 explosion, not a boiler explosion but a rupture? 8 MR. SPEIS: You mean an overpressurization type. l 9 COMMISSIONER BERNTHAL: Yes. l 10 MR. STELLO: We have had information which suggests 11 that that might be possible. The Soviets have also clearly 12 stated they had a chemical explosion. I don't believe, until 13 they give us a report, we are going to be able to give you the 14 answer with any factual basis. 15 MR. SPEIS: But you can postulate scenarios where 4 4 16 you can have overpressurization not only from the steam but 17 from the other combustion products, before they even burn. 18 The graphite fire has burned down. Some or all of 19 the molten core material is probably on the reactor cavity j 20 floor. That's only speculation. i 21 Concern has been raised for the molten core that it 22 could possibly penetrate through the two suppression pool 23 basemats. The Soviets have stated that the reactor is f 24 stabilized and are reported filling the suppression pool 25 cavity with concret,e and injecting nitrogen into the core L __,... _ _. _ _ _..., ~,,., _

25 1 region. 2 As Mr. Stallo said, the remaining three units are 3 reported to be shut down and are being properly cooled. There 4 are many possible scenarios from Chernobyl that can lead to 5 the damaged core, but as we have said, we still do not know 6 what the actual sequence of events was. 7 CHAIRMAN PALLADINO: I want to come back and ask 8 some questions about that. 9 MR. SPEIS: Okay. 10 The next Vu-graph please, 18. 11 (SLIDE) 12 MR. SPEIS: I want to say a few things about the { 13 sources of the environmental data now. As all of us know, 14 elevated levels of radioactivity were detected in more than 15 ten countries, both in air, rainwater, soil and food in many 16 European countries. 17 The radionuclides that have been detected include, 18 among others, iodine-141, cesium-147, cesium-144, ruthenium, 19 molybdenum, neptunium-249, zirconium and niobium, among 20 others. 21 Sweden and Finland provided activity measurements as 22 a function of time beginning shortly after the accident. This 23 is very useful information because ve can use that 24 information, as you will see shortly, to try to determine the 1 25 severity of the release.

.s 26 1 Based on those early measurements from Finland and 2 Sweden, we estimate that the release was an early puff type of 3 releas.; and it was augmented in a continuous fashion. You 4 know, it was sustained and very constant for a few days. 5 Next Vu-graph, please. 6 (SLIDE) 7 MR. SPEIS: Based on the source term, we have used 8 these measurements from Sweden and Finland and other places 9 and attempted to extrapolate what the dose or the severity of 10 the event was. What we think happened was that, based on the 11 information on the measured doses at large distances, 12 primarily in Sweden and Finland, from the accident site, this ( 13 type of release and the type of measurements that were taken 14 is indicative of a very large and energetic release of 15 radionuclides. 16 In fact, in order to get the doses measured in 17 Sweden, the plume had to be very high, maybe as high as 1500 18 meters, and more or less take a direct path into Sweden.- We 19 understand that the weather conditions were such the first few 20 days that more or less the plume traversed a direct path 21 before it started swirling around to different parts of the 22 continent. 23 Also, in order for the plume to be as high as 1500 24 meters, it had to be energetic, and we know that the energy 25 was there, the explosion with the subsequent graphite fire,

27 1 and the high temperatures. 2 Now, what we have done, we have gone into previous 3 studies from severe accident consequences and looked at the 4 plots of dose versus distance, and based on those, we have 5 extrapolated what, assuming that you did have a severe 6 accident release and assuming that the doses measured in 7 Sweden were relevant to that release, what is the relationship 8 between the two. 9 When we look at those calculations and those plots 10 and the way they were extrapolated, we are able to deduct that 11 the releases were very severe, of the order of, maybe, most of 12 the noble gases, maybe 30 to 60 or 70 percent. We are talking l 13 about releases that have been calculated in WASH-1400 and some 14 of the studies that you are familiar with. 15 of course, there are uncertainties, and as you see 16 later on in some of the assumptions that we are making to come 17 up to that estimate, it involved a number of assumptions. 18 Let's go to the next Vu-graph so I can talk about 19 the factors that we used in coming up with those results. 20 (SLIDE) 21 MR. SPEIS: The extrapolation factors assumed that 22 the dispersal in air was proportional to the distance to the 23 minus 1.5 power. This type of number is based on experiments 24 and calculations that have been done in the past, but it is 25 still an assumption. It could be to the second power or

28 1 something less than 1.5. /-~. 2 The other thing we assumed was that the radioactive 3 decay was about a factor of 10 for radioiodine and a factor of 4 2 for noble gases. As regards the cloud depletion, it is 5 likely that a substantial fraction of the radiciodines in i 6 particulates would be depleted from the cloud prior to 4 { 7 reaching Sweden. In this analysis we have assumed that 90 8 percent would be deposited prior to reaching Sweden. i 9 - CHAIRMAN PALLADINO: What was depleted? ) 10 MR. SPEIS: The radioiodine in the particulates. 11 CHAIRMAN PALLADINO: In particulates. 12 MR. SPEIS: Yes. We assume that 90 percent l- [ deposited somewhere before it reached Sweden. 13 14 COMMISSIONER BERNTHAL: A factor of 10 depletion, or 15 decay, rather, in radiciodines? 16 MR. SPEIS: Yes. A factor of 2 for noble gases. 17 COMMISSIONER BERNTHAL: Three half-lives in 24 18 hours, basically. Is that what you are saying? i 19 MR. SPEIS: A factor of 2 for noble gases. I think J 20 we used a factor of 10 for radioiodines. 1 21 MR. CONGEL: For the shorter lives, 133s and 135s. 22 MR. SPEIS: That is all of them together. 23 COMMISSIONER BERNTHAL: Oh, I see. 1 4 24 MR. SPEIS: Lump sum. I'm not talking about all j 25 131. I'm talking about everything. E ,,-.,,.m_. ,--,.-.-+-.,,-,-,,-n.-,,_,a.,n,-,mn,enw..n...,..n,.,,w-,mern,.,w., .r-, n,e ., ~,,, - -.,., -. -,.., -

29 1 COMMISSIONER BERNTHAL: Sorry. I am still not 2 getting it, then. The assumption is that the dominant 3 half-life, at least before it reached Sweden -- I guess what 4 I'm trying to get at is how many' days you assume passed from 5 the time of the event and the time of detection. 6 MR. CONGEL: About two days. 7 COMMISSIONER BERNTHAL: All right. 8 MR. SPEIS: Now, using an approximate distance of 9 750 miles from the site to the Stockholm area, we have used 10 the extrapolation factor of 10 to the 6th for inhalation of 11 radioactive iodine, and a factor of 10 to the 5th for exposure 12 of the whole body to noble gases. 13 { So, based on this type of analysis -- 14 CHAIRMAN PALLADINO: I'm sorry, I missed it. It was 15 10 to the 5th for what? What does that represent? The value 16 for what? 17 MR. SPEIS: That is using an approximate distance of 18 750 miles from the site into Sweden, the extrapolation factor 19 is 10 to the 6th for inhalation of radioiodines, and a factor 20 of 10 to the 5th for exposure of the whole body to noble 21 gases. 22 CHAIRMAN PALLADINO: All right. 23 MR. SPEIS: So, as you say, there are a lot of approximations here, basically. 24 25 COMMISSIONER BERNTHAL: I am still having trouble

30 1 with radiciodine. I'm sorry. A factor of 10 decay, and yet 2 two days from the site. What is the dominant isotope there? 3 MR. CONGEL: It is 131, but we were only talking 4 about the whole inventory of radiciodides. 5 COMMISSIONER BERNTRAL: I understand. 6 MR. CONGEL: If you put a factor of 10 in on a 7 radionuclide-specific basis, it gets rid of virtually all of 8 135, a substantial fraction of the 133, and leaves the 131 9 that was the predominant contributor in Sweden. 10 COMMISSIONER BERNTHAL: Okay. I 11 MR. DENTON: And this is some, thing we are modeling 12 better and better as time goes by, but I think we are 13 describing some of our initial estimates here, which look as l 14 good as any we could do fancier. i 15 CHAIRMAN PALLADINO: I said at 3:45 I was going to 16 try to give Jim a chance to ask his questions. Maybe we could 17 go through the rest. 18 MR. SPEIS: I have one more Vu-graph, Mr. Chairman. 19 No. 21, please. 1 i 20 (SLIDE) 21 MR. SPEIS: This indicates the estimated doses. 22 There are three columns here, or three lines. We have the 23 measurements taken in Stockholm and in Finland. You see 24 doses, whole body doses of 2 rem whole body, 10 rem thyroid 25 in Stockholm, 5 rem whole body and no data for thyroid in

a 31 4 1 Helsinki. 2 What we have done here -- 3 CHAIRMAN PALLADINO: I don't understand your units. 4 MR. SPEIS: Okay. I will explain. 5 CHAIRMAN PALLADINO: This is.005 what? 6 MR. SPEIS: The units shown here are in rem. 7 CHAIRMAN PALLADINO: Rems. 8 MR. SPEIS: Let's start with the first one. Whole 9 body dose in Stockholm, .002, which is equivalent to 2 ram. 10 CHAIRMAN PALLADINO: Millirem, 2 millirem. 11 MR. SPEIS: Two millirem. Okay. I 12 CHAIRMAN PALLADINO: That is what was bothering me. ]I[ 13 MR. SPEIS: I'm sorry. Yes. The way we got this, 14 the radiation levels in Sweden were about 2 to 14 normal. It 15 was ranges. So we took the mean of that, and the mean of that 16 is about 50 microrem per hour, and based on an assumption that I i 17 the explosion took place for two days, this gave us the.002 l 18 rem. l 19 Similarly for the thyroid of.01. We assumed -- l 1 20 let's see what numbers we used there. We used I-141 in l 1 21 air. We used an average volume of so many Becquerals per cubic j 22 meter, and assuming a two-day exposure, we got the.01 ren, or 23 10 millirems. Similarly for the Helsinki measurements. 4 1 { 24 Now, based on the preceding extrapolation that I j 25 discussed, the dose within one mile downwind of the plant, i __~ . - - - _... _ - _ _.. _ _. _ _.. _. ~ _ _ _. _. _ _.,,. _, _ _.., _ _

32 1 assuming, again, one-day exposure, would be greater than 100 2 rem whole body, and greater than 4000 rems to the thyroid from 3 anhalation of radiciodines. This is based on assuming the 1.5 4 factor, the radioactive decay and the cloud depletion. 5 So this completes our presentation. 6 MR. STELLO: Mr. Chairman, I have got some comments 7 that I want to make about what we are going to do in the 8 future, but I would suggest, since Commissioner Asselstine will be leaving, you might want to allow an opportunity, and 9 if it is all right with Jim, I will let that go until'later. 10 11 COMMISSIONER ASSELSTINE: That is fine with me. 12 I have just a couple of quick questions.

Themis, 13 could you talk a little bit more about how the s'ource term 14 that you have estimated for this accident comparec to the 15 WASH-1400 cource term?

16 MR. SPEIS: As I say, we are estimating that most of 17 the noble gases would come out, and iodine could be anywhere 18 in the range from 20 percent to 60 percent. If you recall, l 19 severe accident category 1 and 2, which involve <carly failure l 20 of the containment, released about 70 percent of the iodine or 21 the noble gases, and I have here about 40 to 50 percent of 22 cesium, for ey4mple. If you go to Category, which again was 23 early failure but not as early as the first two, the noble 24 gases were about the same and the iodine was down by a factor 25 of 3, 20 percent instead of 70 percent,,and the cesium was 20 D

33 1 percent instead of 40 percent. 2 You have to go to the lower categories where the 3 containment fails in 10 or 12 hours, much less releases. 4 MR. DENTON: It is fair to say it is still very 5 speculative, though, Commissioner. We started out thinking it 6 might be PWR-1. That seemed to be an overestimate. Then we 7 ended up, I think, somewhere between PWR-2 and 3. Different 8 people have done different estimates, but until we know the 9 exact scenario, we don't know how to correlate the 10 measurements that well with what came out. But I think 11 worldwide, people are kind of ending up in this general level, 12 and ultimately I hope we will be able to pin it down much 13 closer. 14 COMMISSIONER ASSELSTINE: Okay. At least for right 15 now, it is somewhere between PWR-2 and 3. 16 What kinds of health effects or fatalities would you 17 have predicted for a PWR-2 and 3, say somewhere between a 18 PWR-2 and 3 source term? 19 MR. DENTON: Do you mean for a light-water plant in 20 the U.S.? 21 COMMISSIONER ASSELSTINE: Yes. 22 MR. DENTON: I said that because we are trying to 23 stay away from trying to predict what went on at Chernobyl 24 because we don't know the meteorology that well or the 25 evacuation plans.

=_-.- 34 1 COMMISSIONER ASSELSTINE: Yes. I am just curious 2 what would the prediction have been for a U.S. plant. 3 ER. DENTON: And of course, even in the U.S. a lot 4 depends on what the weather was and so forth. 5 COMMISSIONER ASSELSTINE: Yes. 6 MR. DENTON: But with those caveats. 7 MR. SPEIS: We did this in detail during the Indian 8 Point effort, and for example, if the plume was very 9 energetic, we ran some cases and I had Frank look them over l 10 right before we came here, and the effects were very 11 minimal. So the plume and its height and how it is transported 12 is almost a critical factor. We can give ycu the reference of 13 the reports and you can see. 14 COMMISSIONER ASSELSTINE: Okay. But it really 15 depends on the weather conditions. 16 MR. SPEIS: That is very much so. 17 MR. DENTON: If you have fumigation conditions, you 18 can get very high consequences; if you really get an energetic 19 one and much of the material goes up, then you reduce the 20 near-in consequences. 21 MR. SPEIS: It is consistent with our calculations. I 22 MR. STELLO: I can't find the table, but I believe 23 at Sandia we did such calculations in NUREG/CR-2239, and the 24 number of fatalities for an accident of this type would be 25 very large. a-,+. .,,,e -rmv s .e -ne w,_ - n--,,,---,.,--,,e-e aen-. p,., -,,, ,4-, w-

35 i I 1 COMMISSIONER ASSELSTINE: All right. 2 How does the source term that you have estimated for 1 3 this accident relate to the one that the staff had in mind in 4 terms of supporting its conclusions on the severe accident 5 policy statement, its judgment on the acceptability of the 6 U.S. plans? 7 MR. STELLO: We don't know the answer to that until 8 we have a lot more information.than we have. The only thing 9 you have is-the end result of what we would calculate based on 10 the Sandia-type numbers, and as you are aware, the Soviet news 11 reports and everything that we have suggest that so far they 12 have reported 204 people as showing symptoms of radiation 13 injury, and all of those people were people who were on site 14 dealing with the accident, either firefighters or workmen, and 15 in no member of the public has there been a report of 16 radiation symptoms of radiation sickness. 17 This would suggest that perhaps the source term may 18 not be as severe as we had been predicting, but that is 19 speculation and conjecture. Until you have a lot more 20 information, I don't think you know. I hope we do get that 21 information. It would be extremely valuable information. We 22 are going to make every effort we can to get it. i l 23 COMMISSIONER ASSELSTINE: Does this event tell us 24 anything about the advisability of considering-offsite 25 decontamination costs in terms of doing things like - - _. _ _. - _ - _ =.. -. =,.

36 1 cost-benefit analyses? 2 MR. STELLO: Without more information, you can't 3 even begin to try to answer such a question. 4 CHAIRMAN PALLADINO: I'm not sure I understood the 5 question, Jim. 6 COMMISSIONER ASSELSTINE: I guess what I am 7 wondering is to what extent do we know if there was any 8 offsite decontamination, and what does this tell us about the 9 advisability, if we are going to do things like cost-benefit 10 analyses, of factoring in something other than just offsite a 11 health effects: that is, having to clean up offsite areas. 12 MR. STELLO: You recognize our calculations and the 13 reports I'm referring to include them. 14 COMMISSIONER ASSELSTINE: Yes. 15 MR. STELLO: They do, in fact, judge the amount of 16 land that would be lost as a result of contamination offsite 17 and be lost for extended periods time, include those costs in 18 the cost studies that we have done. Now, I think your 19 question is does it change that? Without the numbers, we 20 don't know. 21 MR. DENTON: Let me try to answer that in a little 22 different way. I think one lesson that may ultimately come out 23 of this in comparison to TMI, TMI was an accident beyond the 24 design basis event, but we were able to terminate it and turn 25 it around and not have large offsite consequences because the

. _ =. 37 1 containment functioned so well. 2 It may be that in a reactor such as this, with the 3 five times more zirconium than in a light-water plant and the 4 2000 tons of graphite at high temperature, it may be that once 5 that plant gets beyond design basis, it is much tougher to 6 turn it around, and the area which we talk about between i 7 design basis and severe accidents, this plant may be a lot 8 harder to keep from turning into a major release than, say, 9 TMI was. 4 10 Now, not knowing enough about the cause, it is a bet 11 speculative, but you can contrast it to TMI where everything 12 stayed inside the containment that was released, essentially. / 13 Here that wasn't the case. So I don't know how that bears on 14 the overall policy question per se, but I think it does get 15 back to the effects on this containment. 16 COMMISSIONER ASSELSTINE: In terms of the sequence of 17 events, do we know where, if at all, something like a hydrogen 18 explosion might have occurred? Do we have any idea what blew 19 the roof off? 4 20 MR. STELLO: I think that was the reason that you 21 saw on the slide explosion (s) with an "s." If it were a steam I 22 explosion, for example, first and then the roof were gone, it i 23 could have been followed by other explosions for other 24 reasons. You don't know. l 25 MR. DENTON: We have had a different scenario ,-,,_,,,..,....,-,p. -,,_-,.,-,nn.,-m.,-

38 1 epaculated cvory day from o difforcnt courco, and I think 2 until we are informed more clearly, there will continue to be 3 speculation. 4 CHAIRMAN PALLADINO: One scenario that I was reading 5 about talked about the whole thing starting in a turbine 6 generator room and causing the asphalt floor to catch fire and 7 loss of cables and power control to the emergency power. 8 MR. DENTON: That was a favorite speculation at one 9 time, but I don't know any reason to think it was the actual 10 basis other than any other one that we have talked about. 11 CHAIRMAN PALLADINO: Well, I was going to ask what 12 may appear a naive question, but was there enough hydrogen in 13 the generator to cause a significant explosion, assuming it is 14 a hydrogen-cooled generator? I don't even know that that is 15 true. 16 MR. DENTON: I am told their generators use hydrogen 17 pretty much the same way ours do. You are talking about the 18 turbine, the generator part. Yes. There is quite a bit of 19 hydrogen, I guess, there, enough to produce fires. 20 MR. STELLO: We have had fires in the turbine 21 generators as a result of it, but nothing in any of our 22 experience suggests on a scale, looking at the damage to that 23 building, nothing that I have seen suggesting the potential 24 for that kind of damage, based on our own experiences. 25 CHAIRMAN PALLADINO: Excuse me, Jim. l -r-g g n., y-

w---

y. ,,m,7,, ,,-w yy 3 ---w---v-yv y,-

39 1 COMMISSIONER ASSELSTINE: Mcybo juct ons lect 2 question before I have to leave. To what extent do we have 3 any basis for being able to predict how effective the Soviets 4 will be in terms of understanding themselves what happened? Do 5 we have any idea what records are available, whether they are 6 going to be able to figure out the sequence of events, or is 7 it just a big mess? 8 I know how long it took us to try and sort that out l 9 after TMI. Do we have any idea what they are facing in terms 10 of difficulty understanding what went on? 11 MR. STELLO: Yes. Based on what we did at TMI, their 12 task is far more difficult than ours. I don't have any reason 13 to doubt that they will do everything they can to be as 14 thorough as they can in understanding it. Clearly, they have 15 got an awful lot at stake, and I am sure they are as 16 interested in learning those lessons as we are. We are 17 perhaps more anxious because we are removed from the 18 information. l 19 I am sure there are a lot of people in the Soviet i 20 Union that have some fairly good ideas about what happened, 21 but I commend them for waiting until they finished their work 22 and then getting up and saying this is what has happened, 23 rather than the scenario at TMI where every little piece that 24 got peeled off moment by moment, the good information and the 25 bad information, gets out. They are a closed society and it I

40 doscn't work that way thora, so I think whsn wo get it we 1 2 ought to be able to get a job that is a pretty carefully 3 considered job. 4 I think there is some speculation that that may 5 happen sometime this summer, but I know that their task is 6 very, very large. 7 COMMISSIONER ASSELSTINE: Why don't I stop there. 8 Thanks, Joe, for letting me ask my questions. 9 [ Commissioner Asselstine leaves the meeting.] 10 MR. STELLO: Do you want me to finish the last slide 11 first? 12 CHAIRMAN PALLADINO: Yes, why don't you go to the 13 last slide, and I will limit myself to three questions at the 14 start. 15 MR. STELLO: We are having Themis and the people who 16 have been following this to try to pull tcgether a report 17 based on all of what we know and the information we collected 18 so we don't lose it, for that purpose. We will start to phase 19 down the intensity with which we have followed it. Themis.and 20 his people will continue, at least for the interim, continue 21 to track what is going on. 22 What we need is to start thinking about the longer 23 term, and you have sent me a memo asking the question of what 24 are we going to do for the longer term. -Harold hss had some 25 discussion and we are still looking at the possibi.lity of

41 1 having a coordinntcd offort within ths United States so there 2 is one report that represents our best understanding of what 3 happened in this accident as a feeder report both from the l 4 point of view of understanding the accident that happensd at 5 the plant and its consequences. 6 Once I have that information available through some 7 source, we then can look at it and ask the questions that we 8 need to ask ourselves, are there lessons to be learned from I 9 what happened there to the U.S. reactors. 10 Based on everything we know right now, we see 11 absolutely no need to go back and make any programmatic 12 changes on what we are doing. We think what we have started 13 out is the right path that we are on. Based on the 14 experiences we have had at TMI, there is nothing we see coming 15 out of this accident that suggests we ought to change what we 16 have been doing, so we will keep doing that. 17 We will make every effort to learn what we can from { 18 the accident. We need to do that. It is important and we 19 want to. Now, if we can't get some way to get this done on 20 the basis of a coordinated effort within the United States, I 21 am going to try to put together a blue ribbon panel of some of 22 our leading scientists working in this area and give them the 23 task of going back and trying to understand as best they can 24 when the information is available what happened. 25 CEAIRMAN PALLADINO: Would you. include people,

42 1 for example, from DOE in there? ~ 2 MR. STELLO: We would hope to, and I have contacted 3 DOE and expressed, in my view, the need for us to be fully 4 coordinated, and they have indicated that they are interested 5 too. 6 CHAIRMAN PALLADINO: With regard to the present 7 systems, you are having a separate look at 8 Fort St. Vrain. Where do you stand on that? 9 MR. STELLO: I hope to be able to send you our view 10 on that by tomorrow or the next day. 11 There are a couple of things that clearly come out 12 in a lesson learned here, the need to have an early warning 13 system available. As this accident.has clearly demonstrated, 14 the consequences went beyond the border of the country in 15 which the accident occurred. It teaches us over and over again 16 an accident anywhere is an accident everywhere and clearly has 17 impacts and concern worldwide, and the need.to have good and 18 accurate information in terms of what is going on is very, 19 very important. 20 I hope that through the efforts of IAEA, something 21 will be developed to improve the situation for the future. 22 There is every indication they are going to try to, and we 23 will need to see. 24 Again, it emphasizes how important it is to share 25 information with other countries. .I hope that the Soviets

-43 I hava mada thtmmelvsn awars cnd availed of the information from 2 TMI. Certainly one of the lessons we learned out of TMI is 3 the need to accommodate the substantial amount of hydrogen 4 that can come from a metal-water reaction. I don't know to 5 what extent, for example, they were aware of and have used all 6 that information, and I am sure there is information about 7 this accident that would be useful in helping our 8 understanding. The need to do that is critical. 9 I don't know when to tell you that these tasks will 10 be finished because they all depend on the availability of 11 this information from the source, which is the Soviet Union, 12 and until that information is available, I can't put any 13 timeline together as to when we will be finished. 14 That ends what I wanted to say. 15 There are a couple of things that didn't get said in 16 the summary, sources of information that I think are 17 important. I have already summarized the health effects in the 18 Soviet Union. I think it is important to recognize that the 19 other three units now, we have confirmed through a variety of 20 vehicles and mechanisms, the other three units are clearly not 21 in any difficulty. They are being manned from the control 22 room. They are being held in a safe condition. 23 CHAIRMAN PALLADINO: Do Units 3 and 4 share adjacent 24 control rooms or are they contiguous? 25 MR. STELLO: We believe it was shared. All of the

44 1 data from ths cccident havo bosn rzcovsrcd the control room 2 and is now being analyzed and studied. 3 The most important point I was trying to make is 4 that those reactors -- the systems that are necessary for 5 keeping them safe have not been damaged have not been damaged 6 as a result of the accident at 4. 1 1 7 One last point in terms of the overall impression 8 from every source of information is that things do appear in 9 Unit 4 to be stable. Dose levels are decreasing, and there is 10 no indication that the melting or further damage is going on. 11 The core is now believed to be below melting temperatures and 12 in a passive state, and with time clearly that will just get 13 better and more favorable. l \\ 14 We have, I think, covered about everything that I 15 thought was important, and now we leave it up to questions. 16 CHAIRMAN PALLADINO: Okay. Well, let me start with 17 three and a half questions. Maybe I've got to count them as 18 four. 19 The first one, the Interagency Task Force, you 20 said, is having its last meeting tomorrow. Are there any 21 provisions being made for sharing information that's learned 22 among the various agencies after the task force goes out of 23 existence? 24 MR. DE TON: I think that will be a topic for discussion tomorrow, Mr. Chairman, among the task force, how 25 ~ wr y w -w-, e -s - ~ ,,m y q

45 1 to phase it.down. Certainly there is extensive sharing going 4 2 on now between the health agencies, based on the measurements 3 being made in the U.S. and a lot of activity going on with 4 regard to import of materials and what acceptable levels are. 5 So we will have to do that tomorrow. Tomorrow there 6 is to be a discussion of how to turn down the high level of 7 activity that has been going on. 8 But basically, I think it's Mr. Thomas' view that 9 after that, it would be up to those agencies involved to make 10 their own arrangements for their own responsibilities, rather 11 than going through him as the central agency. 12 CHAIRMAN PALLADINO: Well, one of the features of ( the Interagency Task Force was the fact that information that 13 14 one agency would have could help another agency, and if they 15 work independently, they won't have that interchange of 16 information. But if they're going to address that, then we 17 will have to wait and see. 18 Can I go to a couple of technical questions. You 19 spoke earlier about there being -- I think it was eight 20 diesels for the two units; four were operating and -- 21 MR. SHERON: No, sir. It was eight reactor coolant 22 pumps. Six operate continuously; two are on standby. 23 CHAIRMAN PALLADINO: I'm sorry. Start over. 24 MR. SHERON: It was eight reactor coolant pumps, six of which operate continuously and two of which are on standby. 25 . ~.

46 1 CHAIRMAN PALLADINO: Oh, I see. 2 MR. SHERON: The plant had three diesels shared 3 between the two units. 4 CHAIRMAN PALLADINO: So it was pumps you were 5 talking about, not diesels. 6 MR. SHERON: Yes. 7 CHAIRMAN PALLADINO: But the diesels don't operate 8 until they're called upon, or do they keep them running, or 9 don't you know? 10 MR. DENTON: I don't think we know. 11 CHAIRMAN PALLADINO: Okay. All right. We got that 12 cleared up. Thank you. i 13 The other question I had, have you eliminated any 14 possible scenarios? And let me tell you why I ask that 15 question. 16 When I started to describe one possible scenario 17 that people have reported on, you said, "Well, that was an old 18 one." Have we formed any opinions about possible scenarios 19 which seem more likely than others, whether you dismiss any of 20 them? 21 MR. STELLO: No. 22 CHAIRMAN PALLADINO: Based on the facts. 23 MR. DENTON: I think we've just tried not to 24 speculate, Mr. Chairman. There have been so many -- a lot of 25 people have had a lot of bright ideas that could have led

47 s 1 perhaps to the results that were achieved, but there's now way 2 of knowing what really happened there, I think, until we're 3 told by the Soviets. 4 CHAIRMAN PALLADINO: Okay. My last question had to 5 do with those check valves on containment. I forget which 6 slide it was. If you could just walk through what you think 7 those check valves do or don't do. It was the one -- 8 MR. SHERON: Put up Slide 14. 9 [ Slide.] 10 CHAIRMAN PALLADINO: I was thinking of this one. 11 The suppression pool -- 12 MR. SHERON: How about Slide 16? 13 [ Slide.] 14 CHAIRMAN PALLADINO: Yes, that's it. I was trying 15 to understand. You have the major piping room. If that's 16 pressurized, then does that blow into the intermediate room? 17 MR. SHERON: Yes. We would think it blows into the 18 intermediate room as well as the suppression pool. 19 CHAIRMAN PALLADINO: So that means that the bottom 20 of the coro vault has to be designed for the same pressure as 21 the major piping room? 22 See, I didn't understand all'these pressures, and 23 I'm trying to understand where -- 24 MR. STELLO: Not necessarily, because when you get 25 the rupture, it's going directly into the pool, and then it's

48 1 going through that valve that regulates it. 2 CHAIRMAN PALLADINO: No. This valve looks like a 3 check valve. 4 MR. STELLO: It's a check valve which allows flow 5 into the other compartment, but also directly into the pool. 6 CHAIRMAN PALLADINO: Yes, I understand. But I -- P 7 Well, what could you say about the design pressure of that 8 core vault? The most conservative would be saying it should 9 be designed for the major piping room pressure, because you 10 have check valves that close on that lower part of the core 11 vault that could conceivably build up pressure in here. 12 I don't know what the functions are, why they have i 13 them, but -- 14 MR. STELLO: It isn't clear to us, but if you look 15 at the picture that Brian had in the previous slide -- 16 MR. SHERON: Slide 14. 17 [ Slide.] l 18 MR. STELLO: Now this is pure speculation on my 19 part. It looks like those valves, the arrangement of those 20 valves, may be put in there to equilibrate pressures among ( 21 compartments, because as you have a break and you discharge 22 the air coming out of all of those compartments into the pool, 23 that has to relieve somewhere else, and if you then 24 equilibrate pressures, you allow yourself to equilibrate the 25 pressure around all of the other compartments coming down, and

49 1 the valves may serve some purpose in doing that, as well as, 2 I'm sure, distributing the water and steam into as many of 3 those downcomers as they can to minimize the pressure. 4 But the details of that design we don't have, and 5 what I've said and anything else we would say also has a 6 certain degree of just pure speculation to it. 7 CHAIRMAN PALLADINO: All right. Maybe that's as far 8 as I ought to go. Let me see if Commissioner Roberts has any 9 questions. 10 COMMISSIONER ROBERTS: No, thank you, 11 CHAIRMAN PALLADINO: Fred, do you have more? l 12 COMMISSIONER BERNTHAL: Let's get back to the 13 earlier question I asked, and maybe I can ask it in a slightly 14 different way. 15 I really was trying to get a sense of where the 16 weakest link is here, to your best current judgment, as to how 17 you have a direct pathway, if indeed you do, between the core 18 or these close to 2000 live penetrations to the core to the 19 environment, because that's, of course, an essential i 20 difference perhaps between our containments and their 21 containments, such as it may have been. 22 What I'm saying, I guess, is that surely having made 23 all of the improvements that they did after they decided to go 24 with some kind of containment concept here, there must have been a lot of smart people that talked about and thought about 25

50 this in the Sov'iet Union, what was the design philosophy that 1 2 we need to -- if it's as you suggest -- to the absence of that 3 pressure boundary on top of the reactor itself? 4 In fact, I thought that there was such a pressure 5 boundary of 27 psi on top of the reactor, but you're 6 suggesting now that there was not. 7 MR. DENTON: Well, I can only speculate, 8 Commissioner, but it appears that they did not want to affect 9 the basic design of the plant by what ever they did to cope 10 with a pipe break, and somewhere along the line they got word 11 about would a pipe break perhaps overpressurize the walls, 12 lose structural integrity, and it looks to me as if they sort ( 13 of just raised the elevation of Unit 3 and 4 enough to put in 14 the suppression pool, but not affect the construction, 15 installation -- they were worried about having a standard 16 plant; this is a standard plant for them -- and just from 17 looking at it, the plant designs I've seen all icok the same 18 above the suppression pool. So that's why I think that the 19 suppression pool function was just to serve the pipe breaks 20 and those boxes that contain the coolant pumps and did not 21 appear to change the design around the core. 22 And it's quite clear that this core has direct 23 access after the accident. So whatever was there was lost 24 during the explosion and the fire,- and the burning was able to 25 go right up through the open roof, which had been blown off. -~

51 s 1 COMMISSIONER BERNTHAL: Is it possible that the 2 requirement or the desire, at least, to maintain the online 3 refueling capability, which of course they have to, in part, I 4 guess, to justify this fundamental design, but there may have 5 been other reasons to wish to maintain that capability -- is 6 it possible that that was part of the compromise? 7 MR. DENTON: I don't think we know, and we'd have to 8 ask them. It looks like it was a design to cope with a break 9 of pipe containing water, pressurized water. And so that's 4 10 why the pressure suppression, not a design to cope with the 11 release of. fission products per se. 12 They may have felt that because of all the ( 13 individual tubes and their ECCS system, which feeds each tube 14 supposedly, that they wouldn't have to cope with sort of the 15 mitigating fission products issue. It was more to cope with 16 the steam and pressure. 17 MR. STELLO: You recognize, I guess last week when 18 we presented this tc the ACRS, we kept trying to decide for 19 ourselves, does that pressure boundary of 27 pcunds go up 20 there, and I believe when we presented this to the ACRS, as I 21 recall, we thought at that time it might be. And then we've 22 done more looking and research and now believe it more likely 23 down below. 24 But even if it were above there, even if it is at 25 the elevation you suggest, you still have 1700 pipes

52 1 penetrating it, which are pressurized to reactor coolant 2 pressure, and if you look and recall the 3 CHAIRMAN PALLADINO: And they are not in the 4 containment. 5 MR. STELLO: They are not in the containment. And 6 those lines that lead from them that are teed in and go off to 7 the headers, they're above that line as well, as you can see i 8 from that picture, and they would all be out there anyway. 9 So maybe it was a difference in achieving the 10 design, or maybe it's our lack of understanding it. Maybe for 11 some reason there's a way in which you can argue that it goes 12 all the way up to the deck, except we can't see anything that 13 suggests it's there, to the deck itself. 14 And it is substantially and significantly different 15 than anything that we're used to seeing and philosophically 16 doesn't appear to have been derived from the same principles 17 that we use. If you lcok at a typical containment that we 18 have, the entire reactor vessel and its piping is clearly 19 within the containment boundary. 20 It's clear from the picture that here you're having 21 at best a very difficult time even trying to decide where to j 22 draw the lines, and it does appear that, based on what we know 23 now, the entire core is in the confinement building, but then 24 we wouldn't call it a pressure vessel in this design. 25 You have 1700 individual thin-wall zircalloy tubes ~

53 -] 1 that are, quoto, the proccurs vescol in thic caco. 2 COMMISSIONER BERNTHAL: Well, okay. Maybe we've 3 gone as far as we can on that. I'm inclined still to reserve 4 a little bit of a benefit of the doubt, because if what you're 5 suggesting is true, then there clearly is nothing that 6 remotely approaches our containment concept, based on what 7 you've just told me. 8 CHAIRMAN PALLADINO: At least in the vault, in the 9 core vault, yes. 10 COMMISSIONER BERNTHAL: That's right. -11 On the question of how much got out and the source 12 term issue, is it conceivable that all of the various press 13 accounts notwithstanding that the chimney effect or-this rapid 14 projection of fission product materials to fairly high levels, 15 as we now seem to suggest, that that would make it possible 16 that everybody is right to some extent here, that the ejection 17 through the roof of the reactor er what was the reactor 18 building was with sufficient force and sufficient height that 19 the actual levels that were measured in the vicinity of the 20 plant may not have been extraordinarily high? 21 And would that then suggest that you might find 22 relatively high levels farther out, depending on 23 meteorological conditions, of course, and on where rain might 24 have been falling and not falling? 25 Would you comment on that?

54 1 MR. CONGEL: I would encwor yca in part to your 2 point. We looked at various meteorological scenarios, to see 3 how the material would disperse in the environment. Depending 4 upon the height it ultimately reached, you could have a peak 5 and a dose as far out as ten miles or so from the release 6 point. That ten mile point, in our judgment, is really the i 7 critical point, without more data on-site or closer in, it's 8 difficult if not impossible to normalize the curve. 9 COMMISSIONER BERNTHAL: Let's ask a question about 10 100 miles, for example. Is it conceivable that even though 11 you measure what appear to be and are by the Soviets' 12 accounts, not extraordinarily high levels, at the five mile, 13 ten mile distance from the plant, but nevertheless you could 14 have relatively high levels at many miles distance, perhaps 50 15 or 100 miles, depending again on this chimney effect and how 16 much really got injected at a fairly high level. 17 MR. CONGEL: What do you mean by "relatively high 18 values?" We have done projections to look at what the values 19 would be, at distances of 50 and more miles from the site. We 20 come up with what I consider higher values then we are 21 certainly accustomed to seeing in normal circumstances. If 22 that's your point, yes. 23 COMMISSIONER BERNTHAL: You are not sure if there is 24 an uniform fall-off, it is a simple function of distance? 25 MR. CONGEL: No, sir. After we did the rough cut n,

55 1 calculation drecribed earlier, wo hnvo b0cn' working with 2 several of our laboratories using regional meteorology to see 3 if we can reconstruct the dispersion of the material. On that 4 basis, we've come close to predicting what we have seen as 5 measured values in close-in countries, for both ground 6 deposition as well as ambient rates. 7 COMMISSIONER BERNTHAL: One last question and then I 8 will pass the torch. It is terribly important or crucially 9 important, as you know, that we get information on this source 10 term issue, that we get good data on the very point I have 11 been asking about. 12 Do we know anything about the extent of the network / 13 of their monitoring capability? We have quite a large network \\ 14 of TLD's and other monitoring equipment in this country. Have 15 they said anything yet about the completeness of the data they 16 will be able to get? 17 MR. STELLO: Based on what I understand right now, 4 18 they have devoted a great deal of their energy in terms of 19 making sure they have been dealing with the accident and doing 20 the things that are necessary. I don't believe they have 21 focused a great deal on systematically collecting all the 22 information that is there, but at least there is a suggestion 23 that there is clearly quite a bit of it and it needs that 24 pulling together. Whether they will share it with us or not, i 25 I don't know.

56 1 Thsy havo agre d to provido information daily from 2 six monitoring stations, to provide us with some insight as to 3 the daily occurrences. The kind of information you are i t 4 looking for, with a net of measurements throughout the area 5 around the plant, the impression is there is quite a bit 6 there. Whether it is anywhere near what we have or good 7 enough, we can't make that assessment until we have a chance 8 to see it. We are hopeful they will provide it to us. It is 9 not clear that they will. 10 MR. DENTON: Just to amplify what Vic said, not only 11 is the source term indeterminate basically, the meteorology 12 didn't behave according to the normal set patterns. The wind 13 did not blow across Russia. It blew up and then there was \\ 14 wind sheer. Some went west. Some went east. The 15 meteorologists are quite concerned also about being able to 16 pin down what was measured so you can go back and improve our 17 model. It is clear this was a global release. It did not 18 behave according to traditional down wind models. 19 There are a lot of student thesis' waiting to be 20 developed when this information does become available. 21 COMMISSIONER BERNTHAL: I have a. couple of other 22 questions, but why don't you go ahead. 23 MR. SPEIS: Excuse me. I would like to make a 24 clarification. You were right to be perplexed earlier by the 25 factor of ten. The factor of ten was a combination of ,. _. -.. -, _ _ _ -,,_,,_.,_._ - _... _,._.,..~ __,, _. _... _,., _ _ _., _. _,,. _ _ _, _.. _

57 1 radioactive dccay and cloud dsplction for iodina. You wora 2 right. 3 COMMISSIONER BERNTHAL: Thanks. 4 COMMISSIONER ZECH: Just a few comments. First of 5 all, it is sure clear that we need the facts and we ought to 6 try to do everything we can to get the real facts as soon as 7 we can. Also, I think it is important that we ensure that the 8 calculations that we are making, the codes, the models, and so 9 forth, are coordinated with those other folks that are looking 10 into this accident, so that we can kind of come up with, if 11 possible, a consensus of not only the results of the accident 12 but perhaps even what happened, until we can get more ' ( information from the Soviet Union. 13 14 It also seems very clear to me that their reactor in 15 whatever we might call it, a housing, I think you called it, 16 that's a rather different design than anything we have. 17 Clearly the design is so different. I think also very clearly 18 you can't help but conclude, perhaps prematurely, but just 19 looking at the slide you have up there, that there is a different emphasis on safety in the Soviet Union than we have, 20 21 from the design itself. 22 Those are things I know you are going to be looking 23 at very carefully. We need to carefully review all the facts 24 and learn all we can. There is no question about it. This is 25 a great responsibility; we have to do that.

58 Iwouldagrsothatatthistimo,thorais"bo 1 2 regulatory changes based on our present knowledge th.it are 3 needed, and based upon our present knowledge and understanding 4 of what happened. I think we should be very vigilant to learn 5 the lessons from this. I know that is going to take place 6 here in the next weeks and months. 7 We also have to make sure that when we analyze those 8 lessons and look at them carefully that our primary goal is to ' 9 do what,we can to contribute to safety; public health and 10 safety as our mission.' f 11 Those are the things I think we should focus on, not 12 just try to jump to conclusions. I think it is important to 13 keep our cool and to be thoughtful and careful and analytical 14 about what we do. 15 j The EDO mentioned about getting a team together. 16 That may be a very important initiative to take, a team of. 17 experta. It seems to me we also should perhaps, we, the l 18 United States Government, should.in some way or another urge 19 the International Atomic Energy Agency, IAEA, to take a lead 20 in making a coordinated effort that could be participated in i 21 by all nations. It seems to ne'1this is very important. 22 Mr. Chairman, I hope that in some way or another, if that is not done, we could help dith that initiative. We 23 24 should contribute to that effort, in my view, and participate' l 25 in it. It is an international concern, an international + ~ ~ ~ - = = ' * " ' ' ' ' " ~' ' ' ' ' ' ' ' ' " ' ~ ~

~~

59 l 1 cvsnt. I would liko to think that our Governannt would 2 participate and cooperate in such an endeavor. As a side 3 issue, if we found it necessary for our own team to analyze 4 those results, that might be appropriate. 5 It seems to me we should at least support strongly 6 international -- in that way, we would be involved with other 7 nations, experts from other nations, that could assist in this 8 analysis. It seems to me that is kind of the approach we 9 should take. 10 MR. STELLO: We have at least preliminary 11 discussions to see if we could get an international study team 12 pulled together. Maybe it is too early to make plans like 13 that. I think it is important. If we could do that, that { 14 would be the best of all worlds. 15 COMMISSIONER ZECH: I think it is the best way to 16 go. Mr. Chairman, I suggest we do what we can to support that 17 initiative. 18 CHAIRMAN PALLADINO: We might want IP to think 19 through what initiatives we might want to propose to IAEA, and' 20 I would mention also the early warning system that I think 21 they could help develop. 22 MR. STELLO: I will do that, i 23 CHAIRMAN PALLADINO: Fred had a couple. 24 COMMISSIONER BERNTHAL: If I could try and get very 25 short answers to these; there are a couple of other things

w-s 60 x- .] 1 hsra I'would lika to clcar up in my own mind. 2 I thought that the Soviets had suggested a steam 3 pipe explosion rupture as'the initiator. Is that true or 4 false? 5 MR. STELLO: That's true. 6 CHAIRMAN PALLADINO: It is true they suggested that? 7 MR. STELLO: They suggested that. 8 COMMISSIONER BERNTHAL: In that case, it could well 9 be a steam explosion of some kind, other explosions following 10 that. 11 MR. STELLO: Or the other way around. 12 COMMISSIONER BERNTHAL: They are suggesting the o 13 former. ( 14 MR. STELLO: They are suggesting there was a steam 15 explosion. It isn't clear to me that was the only or the 16 first. 17 CHAIRMAl[PALLADINO: When you say "they," what 18 segment? Is this/pcmebody who thinks he heard a steam 19 explosion? ~ 20 MR. STELID: There were individuals who thought they 21 heard more than one explosion. 22 CHAIRMAN PALLADINO: Were they technical people? 23 MR..tTELLO: I don't knew. 24 - MR.,DENTON: We'have read the transcripts of thei'r 25 press releases carefully. They_do usa:" steam explosion." s K Ww* a N 9 4 i _ta

61 1 Thny uccd " human error # quite a bit. They have used "several 2 explosions." It is clear that none of these represent the 3 simple sort of scenario. Their way of describing it varies 4 from day to day also. I don't think we are able to pin it 5 down. 6 COMMISSIONER BERNTHAL: We do not yet know whether a 7 steam explosion was the initiator? 8 MR. DENTON: Correct. i 9 MR. SPEIS: Commissioner, I think it is also j 10 important to stress that even though they might say there has ) 11 been an explosion, they might have meant something different 12 from what we mean when we say a steam explosion ourselves. (' 13 COMMISSIONER BERNTHAL: A second quick one; do they 14 use the term " design pressure" the way we do, when we speak of 15 design pressure capability here? Are they talking about 16 failure pressures like in our case, two to three times? 17 MR. STELLO: We don't know. 18 COMMISSIONER BERNTHAL: Do we know how much of the 19 total fission inventory -- can you estimate now how much of 20 that was released in the accident? What percentage? l i 21 MR. SPEIS: We said earlier that the first 22 approximation is most of the noble gases and a large fraction 23 of the iodine, anywhere between 20 to 60 percent, and a factor 24 of three or four, considering the uncertainties, is not 25 unreasonable. It could be even more than that. . _ - - _ - _. _. ~... _ _

62 1 COMMISSIONER BERNTHAL: What fraction of the 2 radionuclide inventory of the core does all that represent, in 3 your judgment? I know you don't have exact numbers. 4 MR. CONGEL: We are talking roughly half, to a first 5 order. 6 COMMISSIONER BERNTHAL: We continue to believe that 7 half of the radionuclide inventory of the core was released? 8 MR. DENTON: That gets into definitional issues, 9 too. I think most people -- some of the European countries 10 have estimated maybe 15 to 20 percent. I think that means the 11 more volatile elements. When you say total inventory, do you 12 mean those things that are expected to come out or not { 13 expected? There have been very few measurements of actinides, 14 for example, made. Plutonium 239 has been detected and 15 apparently there have been traces of plutonium detected, but 16 not much because they are alpha emitters and harder to detect. 17 I think it is really hard to push this; it is 18 somewhere between 0 and 100, obviously. To try to pin it 19 down, the data just won't permit it'. The clouds appear to be 20 floating up there, even over the U.S., in these higher 21 elevation ranges. We don't know how much material is up there 22 until our meteorologists and dispersion calculators can -- 23 there is no way to know a priori from the knowledge we 24 have, how much got out. 25 COMMISSIONER BERNTHAL: Let me ask it a different

63 1 way. For the kind of~rolcaco that wo normally concarn 2 ourselves with in source term work, broadly speaking, what 3 fraction of the inventory for those worse case scenarios do we 4 think this represents here? Can we get a rough estimate of 5 that? 6 MR. STELLO: I think the answer that Frank gave, 7 roughly 50 percent, as a restit of a back calculation to say 8 that the source term had to be on that order to produce these 9 results measured at those distances at this time. I think to 10 get beyond roughly 50 percent is not possible right now. 11 MR. DENTON: I like the answer the other way, that 12 most of.the noble gases, a lot of the halogens and some small ( 13 percentage of the actinides, depending on their volatility. s 14 MR. SPEIS: The only actinide that was measured was 5 15 neptunium. You know that neptunium has a very low 16 temperature, a melting / boiling temperature. It is almost like 17 a volatile, to some extent. 18 CHAIRMAN PALLADINO: Let me make one or two 19 observations. I think periodically we ought to get briefed as 20 we develop more information. I suggest we take that up at 21 agenda planning, give us your best estimate when it might be 22 most useful for us to receive new inf,ormation. 23 At the last agenda planning, we also talked of 24 having our technical assistance briefed each day on any 25 important changes that have taken place. Has that been . - _ - - _,. ~...

64 1 initiated? 2 MR. STELLO: Yes. 3 MR. SPEIS: We had the last one yesterday. When we 4 develop more information, we will call them. 5 MR. STELLO: Our responsibility is to make sure the 6 Commission is kept informed of significant issues. We will 7 fulfill that responsibility. 8 CHAIRMAN PALLADINO: I found this very helpful. I 9 think we all want to be kept abreast as much as we can. We 10 want to make sure that we make optimum use of your time and 11 our time as well. 12 Let me thank you all and we will stand adjourned. 13 ( [Whereupon, at 4:35 p.m., the meeting was 14 adjourned.] 15 16 17 18 19 20 21 22 23 24 25

1 2 REPORTER'S CERTIFICATE 3 4 This is to certify that the attached events of a 5 meeting of the U.S. Nuclear Regulatory Commission entitled: 6 7 TITLE OF MEETING: Staff Briefing on Chernobyl Accident (Public Meetin 8 PLACE OF MEETING: Washington, D.C. 9 DATE OF MEETING: Tuesday, May 13, 1986 10 11 were held as herein appears, and that this is the original 12 transcript thereof for the file of the commission taken i 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 18 AJS 2 a-Mari ynn M. Nations 19 20 21 22 Ann Riley & Associates, Ltd. 23 24 25

l~ ) 4 STATUS BRIEFING ON THE CHERNOBYL NUCLEAR ACCIDENT PRESENTATION TO THE C0lHISSION MAY 13, 1986 liiEMIS SPEIS,. DIRECTOR BRIAN SHERON, DEPUTY DIRECTOR DIVISION OF SAFEIY REVIEW AND OVERSIGHT OFFICE OF NUCLEAR REACTOR REC 4JLATION AND INCIDENT TRACKING TEAM e 5 y- ,,y,._. ,y---

e 0 9 e 1. NRC IlWOLVENNT 2. SITE AND PLANT DESCRIPTICN 3. THE ACCIDENT EVENT DESCRIPTION SulfARY AND STATUS AS OF 5/12/86 RADIOLOGICAL DATA 4. R EJRE PLANS 4

2. DESCRIPTION OF THE CHERNOBYL SITE THE CHERNOBYL REACTOR SITE IS A 4 UNIT SITE LOCATED ON THE PRIPYAT RIVER APPROXIMATELY 10 MILES NORTHWEST OF CHERNOBYL CHERNCBYL IS A SMALL TOWN LOCATED APPROXIMATELY 60 MILES NORTH OF KIEV POPULATIONS - KIEV - 21 MILLION - PRIPYAT + 3 OTHER NEARBY TOWNS - 49,000 WITHIN 18 MILE RADIUS - 150,000 TO 180,000 - WITHIN A 100 MILE RADIUS - 7 MILLION TERRAIN APPEARS TO BE ROLLING HILLS ALL FOUR UNITS ARE,RBMK-1000 CLASS PLANTS. UNIT 1 OPERATIONAL AROUND 1981, UNIT 4 OPERATIONAL IN 1983. TWO K)RE RBM(-1000 CLASS UNITS CURRENTLY UNDER CONSTRUCTION AT SITE. APPROXIMATELY 1 D0 ZEN RBMK-1000 CLASS UNITS CURRENTLY IN OPERATION IN SOVIET UNION

i ".. g Z : : % w %tes3#F259Eamprst sanaam l,,, --gn e an => u. ~,..

y v N

9e k.;E,k.. u,$1 b I h

g ',

-* g. ., g3 /,/ g,, = -~ y j mg r =-, q i += - g: 3 ed ((i8 Y.,. [h 5%M~phk i _ a;,;..q;cj 4.p= gmg ~ pcel-l Rh 7 .w.y y,.. k k l. f } r p.,.L 4, ~ .i e r .e(f s,,'4M.A: $%29. w w 3 s 1 4.A m-w 3 g m.. q.,_ w

3.-

3 -.as, hn A JD..i.";.M

y.?

c + geB

t..

,k N ..a n '. g s u_ *.. w w (:. a -ay s w,, k' 5 ~; \\ g zr M ~. N; )

hha.w tzA4e@Miki... " 3*_$_,' _E ~

i 6AR -[s ;1d.>.; .u em-8x. ww ~ .s ;/,., \\ 6:e ? S mr r x'

%ran.ns,usn a,\\ s.-n

.M e. cF1 l,. \\ '4{ 4 d rt-b c ~ E \\ H f.*

g N',

\\~ h ..Mi f, ,6 j\\ / ~ xdi I I C- 'n. M-1hW^--

\\ CHERNOBYL PLANT CHARACTERISTICS

RBM(-1000 PLANT DESIGN IS SIGNIFICANTLY DIFFERENT FROM C0ltERCIAL U.S. REACTORS THE CHERNOBYL UNITS (RUSSIAN NAE RBMK-1000) ARE DIECT CYCLE BOILING-WATER PRESSURE-TUBE REACTORS EACH UNIT IS PATED AT ABOUT 3200 MWT

] TE REACTOR FUEL IS CONTAINED IN A LARGE NUMER (~1660) 0F INDIVIDUAL ZIRCALOY PRESSURE TUBES IEEDDED IN A MATRIX OF GRAPHITE BLOCKS. EACH PRESSUE TUBE CONTAINS 18 ZIRCALOY CLAD UO. FUEL PINS ~ 2 ENRICHED TO ABOUT 1.8% U-235. THE PRESSURE TUBES AE 8.8 CM (3.5 INCH) IN DIAETER. THE EACTOR IS ABOUT 12M (40 FT) IN DIAETER AND 8M (^ 26FT) i HIGH INCLUDING SIDE AND TOP GRAPHITE REFLECTORS THE GRAPHITE MATRIX IS ENCLOSED WITHIN AN INERTED ATMOSHPERE

ALL IWORMATICN OBTAINED FROM AVAILABLE LITERATURE

gs SIXOPERATINGPUMPS(8PUMPSTOTAL,TWOPUMPSAREONSTANDBY) CIRCULATE COOLING WATER TO THE INLET OF EACH INDIVIDUAL PESSURE TUBE (FUEL ASSEMBLY) THROUGH INDIVIDUAL LIES FOR EACH ASSENLY STEAM IS PRODUCED WITHIN THE ASSEMBLY AND IS EXTRACTED FROM THE TOP OF EACH PRESSURE TUBE AND COLLECTED IN A HEADER COM10N TO ONE OF FOUR STEAM DRUMS CONTROL IS ACCOWLISHED WITH 211 BORON CARBII'E CONTROL RODS THE CONTROL ROD CHANELS ARE COOLED SEPARATELY ON LINE REFUELING (ESSENTIALLY CONTINUOUS) E E RGENCY COOLING S,YSTEMS ARE~ DESIGNED FOR MAIN COOLANT PIPE BEAK 3 DIESEL GENEPATORS FOR 2 UNITS .,-v,.-.. ~ ,-,,,.n,,. ,-.g..~,- .-4-~ r-.,_. ,,--,...,,.,,.e,

j l q / 8 I n',- - - / A. n)W/,%& ~} f/ s r-d / p / [Y j JT -.G \\

g&;--

gff> \\ f a 's \\ ( 1 +,,,, \\ ...~ 7A&d ..e. 5 9'.. o g.,,3 A.p:*_

. w-...

f'jf. \\ \\ ..a. - . Ky.r-2 ,. & w.4.... ,,5:.3 -W' t -{W<$<- s w \\ _~.T , :..w. 1 h. \\, . p3..p . *-:g i,s.S; f. 58 1 \\ p.s.a. ,y. .'2.* YW ,, 4 y j m* : ;v... '}J:g., [9,g' ? m 'i?- E t $f. e

gg.

.G i:y,k_;.y:- % \\ ~ ~~. . _r2AY ew j.;. .\\ r., . g.,,. g.gl.ys . 5.- gi 95 .~.un. g;, u. i,. '~ ~ .~ b 8 9 /. &g,,l%- e f*?hh&<-Q$ E g U.N$h,g~- - r? a. h '-= ?., ? \\ A*3W-v. '\\ t \\ s

y..,.,

7.-f p i

~

4 Fig. 3-12. General view of the Smolensk nuclear power plant. s-main building; z-auxiliary building and chemical water clean-up building; 0-chcinical storehouse: d-ad ' niinistrative and welfare building; J-Diesci-generator station; s~ liquid-and solid-waste storage facility; 7-uitetsgen-oxygen station; #-3tand by boiler; S-new fuct storage facility I i

1 i gg I l L4?J m- ,m l F l \\ " i !J i H \\ 12 IJ ( 4g ~ m2 ..,....., 7 nk g g g , TITTT1 1.i.1.a ; 1 j 12() ,=, , 12, s Jeg ,.4 .h, / Tr i ly*m L IJ ri a < g 'd J (J L .mTmmnU ETmrmmmn111manm:1110 m L 1] - d.f? b Yh sl~ { g ~; 4' l ,Myl mmm _ u __u _ _ __ = , g r g r I{f \\ M8 [ if P j 2 gg a g f, q 'O, A 4: _- h , p q

9 a

a ~] _%gy ' ~ ~ ' ') lIIImwIl d K s z w pi % 1 - ;p, ag g sp; e 7n ~ l w f 21 E \\ Q $, _d }} ~ 'r u*~ l [ { p_n j AI =- bL'R h-l{, r 3; yc ~'"", b \\ QG. T ~ D 2L M W5 2 * ** h ' I &ijkh %.Q YL, Y. 2M EM._ __7ZM \\ lita 4AW 1 4 i Irig. 3-13. Cross sectional view of the main building at Smolensk i 3

-first-stage condenaste pump; s-825/;:D-t overhead travelling crane J-aeparator-steaan superbcater; d-K-500-G5/3000 steam tusbane; J-con-
0-main circulating punip; #1 -clectric l

denber; d-additional coolcr; F-low-pressure heater; 8-descrator; s-50 to-t overhead travelling crane; motor of main circulating puanp; JS-drunn separator; #3-b0/80-t remotely controlled overlcad travellmg crane; id-refueling mecisanlasu; is-j i HisME-8000 reactor; is-accident containment valves; #F-bubleser pond; Ja-pipe state; is-: nodular control board; Jo-location beneath cuales,4 board roosn; 33-laouse switchgear locallosas; SS-eshaunt ventilations gisant locations; 3J-galenuan vcsailldtiers plant locationg i i l i i i

~ ~ - Q.~,..

.'W*. u '

.d N c.

2. wer. g e,s-t

1. Roseter N N

3. Sasam to weese pipes A Drum seperster

/M@ j i 1 Sesam headers NN L D eusw eniers ' n///

7. Main sirsutation pumps (MCP)

NN h '(,' y y & Geous dispensing headers (GOH) i Water pipelines U :g NN .~~; N

=.-- ""'"

10. Fuel element siedding sentrol system I

p

11. Upper biological shie64 NN

12. Lateral i'", - 'shis6d h

f' N

13. Lewar bielesised shield

.j'*/. 14 Cooling pond NN ,J / 11 Unioadine 4eessag anachsne IULM) h - - ' ~ ' 8.' & / l 9 4 4 p' h [ N ( 14 ( j% 4 4' fl ~ h E-E,j,j 4 e l '{ j'

lh T

1 c ..:l 1 ;- .$K f.f. ej.~i -g (4 1 s, g, 9 i 9 w $N h;,-l, 'I N %' k i)$" % l( $y h @; 0 i l )'%N!! @M$ 1! $,;4 l 'b l7 ',' h n' r s 5.,

.:_-::::5 J : -:::a LO

(- t ' G{s;. O;:g d' h, ,,: E_w:' , '.7 h I i

f Gi

.E I g' / [ ) e

ij

( j A sect 6onal view of the R5MK.1000 tonetos. With as electrical power of 1000 MW, the remeter's thermal power is 3144 MW the cooiant flow is 37J X 108 t/h and steem espacity J.4 X 108 t/h. The renesor talet wiser esenperature is 270'C and the satursted sseam teraperature 284*C with a pressure in the separstor of 70 kg/cm. The imisind feel enrichment is 1.85 8 ~ 1 1 l 4 .s e -w-- -,e--,e-- _e,------,-- -www=,-- _-r,-- -rr-o-. _e-.-ws---,,--g--mwni-=r-mvvw w.--

t 4 l / f. e s 1 t .q... W25-m ~ ' \\g . s gt Fg_ "3 S c c r r - 1 nW. __.* Q4 i. -g es, .py 5,' Irp -{ g <n t...... z ,S= - N i Ib-M & e . s=" ~ u = , E ~ \\ M v,.~ ~u. W '.. .T ] 1 ~. s., { tn: - ;.,tc.. f=.n _x' .x k,\\C '( L .\\ \\ '& ^'T 5 'LgM3 "S,'Q \\ p .se - a.,a-I h M. ~ d' 'g, $0Cd+'.Ye'iin (,[ i. i . -s. .. a -- h 9 q-s e. c w ,l 'kh'*d..y..: '[

.*Q Y Ag

~, 3 ( ~ _T,, i, in, 8 74." _mu.. 4 g ...?'_ m' m i l

n... 'q j,.g. -y'pQ,y=s ~ 4 u 3v. r-V. bF,Ai pN u.3 1 f c ? '.. '. ( 1 L_ L-. b-N%e %':4..:S.,[ F 6 t.\\ _g % < w.'-=- b =_ u. :.i. ..,.,1 *, ,.K..',..g.~.~. f..., - l- . a,. \\. d_ .\\, s _., .=,. J s.,:,.:..... x~. x ~.. . g, g_ Y !.,'. t--'. Q. '. f j y....

z. q1 l

N. .. Pn '~~. ; e. A_ T_ -t s ..e .. ---fv g / -f - y,, 'M ' &m ~ ' L. wEr "**$ . ~ M% l / er-- 7 ., x - l _'

/.

M s -=.,v.n,_~_' =_ nc j. -n.w 3.: e ~- 1_Y "1_E G E '~ ~ _ M,1.n u g - : - ' %.g. f. , p.., 1 3q -;. y __, 3 c=- ~.i!1 y --Wa 2 s,,%M.. ;;'-'- ,.,.,. n w. m g e-.-".v-- '- r;-_ u. - e j , y.j-m -* 6 w i. / r. ,r , ~...i.. a t_ ;.. .. x.. s-a~ _a.n. s,. s s.s p_ .,. ~ n.. 4I - 6. E .,. n ~. L-r- Lems. ww .x,., _J. y .9 ...~ W e

5 l .My-[y:- e h w.s.'. 4.:.x g.... - l k.i g. ~ g :,, ' f. .. :.. )., 9 4 w. T 7 T e c.. iss- {. e A .. l. M, eg f g-7: 7' = q,.. 7. e t g.. .2...r. u ...:, r-g,,:y~ .m 7. r .~. q ;..- i>. 4....: 9 u M f i g 4 1 4 . L. i ..s:,,. x .i i I

i.' 2 To Turbines 1 l 3 g l 12.2 m

j Steam Steam

-l250.mml= Failed Fue1 0 / / Detectors ,f ,f o Q3 r Subass sblies Graphite Downcomers Core I I 7m Main 3 circulatfou Group Dispensin9 Pump Headers [-}Feedwater A Pressure l (- ) ( f Header ~~ U v Tubes u L J Water Pipelines (1600-1700) (e

j Schematic of an RBHK-1000 Generating Unit 1

0

~ DESCRIPTION OF PRIMARY SYSTEM ENCLOSURE REMK-1000 ENCLOSURE PHILS0PHY DEDUCED FROM LITERATURE o PRIMARY SYSTEM DOES NOT HAVE HOUSING EQUIVALENT TO A WESTERN STYLE CONTAINENT 1 o ENCLOSES REACTOR AND MAJOR PIPING WITHIN TWO DRY HELLS o PROVIDES A WEThELL BENEATH THE DRYWELL STRUCTURES o ENCLOSES REMAINING PRIMARY SYSTEM WITH A CONFINEENT STRUCTURE o. ETAL LINED RECTANGULAR VOLUES CURRENT CONCLUSIONS: o WE DO NOT HAVE ENOUGH INFORMATION TO DRAW ANY DEFINITE CONCLUSIONS REGARDING THE CAPABILITIES OF THE PRIMARY SYSTEM ENCLOSURE o IT APEARS THAT THE SOVIET PHILOSOPHY OF CONTAINWNT/ CONFINEENT IS SIGNIFICANTLY DIFFERENT FRChi U.S./ EUROPE.

l ~

,o 6g r;

k u c-w y::;g- -+m. u ( \\ 3! p 0 ( r nJ ' 198 ? \\g5 22 23 H - a..... m...1 !....? p,, f d Lo,,,,,qj""; ." '- " d. H l I fy.. j g q gji l .e f' 75P4P5;a..w-K ' y-- f: [ g Y [f. ll$ l O JZ " M., "i 1 e IJ f 1 , e' 'n. L, i. .2 r 4 / k :. Y '.,X23 t :..:2 .' :2 g ~ ~- .g;og ' o; 9=4:: g 4 0, } m' i y m Y = . ' = - - - - -- - = = T..;.yz r g =' i \\ e ~1 h.:lM IM i hi i ~ u u ,j m m ,L g J q. 4 k ? ?m a . // I(! !.' M',h 1 r 7 . a ,,,,.,,,,,L i: w\\l Ng k, 4Llo &&fg,,,, e is - ?: 't s A} ..L i g e,s gus $ $g i - i.i.i.i$v.If@ m } g )g;! .l li lr4 d 7i in M G g ., _.. di. i i 40M 77pg = e _,,,.,_,_._._m,m__.m. ..m_,, . m ,.__,....,,,,,,,,.-.y...,-x,___,.

~ 1 .i 1 PLANT ARRANGEMENT i j REMAINING PORTIONS j OF PRIMARY.iYSTEM i i 49.6 m (162.7 FT) 4 / REACTOR i \\ I REACTOR VAULT 30 m (98 FT) I l / i i MAJOR PIPING ROOM 1 l GROUND LEVEL (0) SUPPRESSION l C.. POOL (S) j p i I J t 72 m (236 FT) ( t i i 4 4 i 4 i

6 SUPPRESSION POOL ./ ARRANGEMENT REACTOR VAULT MAJOR PIPING ROOM / / e f A i _} w ELL ,{ ,7,.,: J , 7,, SPACE 6 ^ W s r W % n s 1 nl\\s n n s n 4 ,:s,-

,)

. \\.,_(,,,,,,' L,.*e e SUPPRESSION VENT PIPES POOL (S) l OVERFLOW TUBE 1 - SPRINKLERS i J h I .J ~ .l .= 1 y .---.,-,,,-._n-. ,,c,

EVENT DESCRIPTION StWARY AND STATUS AS OF 5/12/86 ON APRIL 26, 1986, AT APPR0XIMATELY 1:23 AM, EXPLOSION (S) OCCURRED ATTHECHERNOBYLNUCLEARPOWERPLANTINl),S.SR, REACTOR HAD BEEN PREVIOUSLY OPERATING AT 7% POWER CAUSE AND LOCATION OF EXPLOSION (S) IS UNKNOWN EXPLOSION (S) LED TO FAILURE OF PRIMARY SYSTEM B0UNDARY, RADI0 ACTIVE RELEASE AND GRAPHITE FIRE DECAY HEAT PLUS HEAT FROM GRAPHITE FIE PRODUCED TEPERATURES SUFFICIBIT TO ELT FUEL GRAPHITE FIE HAS BURNED DOWN, SCtE OR ALL OF NLTEN CORE MATERIAL IS PROBABLY ON REACTOR CAVITY FLOOR CONCEPN FOR MOLTEN COE PENETRATION THRU SUPPESSION POOL BASEMATS SOVIETS HAVE STATED THAT REACTOR IS STABILIZED AND ARE REPORTED FILLING SUPPESSION POOL CAVITY WITH CONCRETE AND INJECTING NITROGEN INTO COE EGION lliERE ARE MANY POSSIBLE SCENARIOS FOR CHERN0F" THAT CAN LEAD TO THE DAMAGED CORE (BUT STILL DO NOT KNOW WHAT THE ACIUAL SEQUENCE OF EVENTS WAS)

a G S 9 SOURCES OF ENVIRONE NTAL DATA ELEVATED LEVELS OF RADI0 ACTIVITY DETECTED IN MORE THAN 10 COUNTRIES SWEDEN AND FINLAND PROVIDED ACTIVIT/ WASUREENTS AS A FUNCTION OF TIE BEGINNING SHORTLY AFTER THE ACCIDENT l J" 1

.a m h 9 SOURCE TERM ESTIMATED BY EXTRAPOLATION OF ESTIMATED DOSE FROM CONCENTRATION WASUREENTS IN FINLAND AND SMTEN BACK TO l CHERNOBYL SIE 4 e 0 1 ENERGETIC AP DSPHERIC PE EASE AVAILABLE DATA INDICATE PROLONGED RElIASE 9 l

t EXTRAPOLATION FACTORS (BACK TO CHERNOBYL SITE) ACCOUNT FOR: s DISPERSAL IN AIR RADIOACTIVE DECAY CLOUD DEPLETION VALUES FOR: EXPOSURE TO NOBLE GASES (1 E+5) INHALATION OF 10 DINES (1 E+6) i l }

l ESTIMATED DC6ES I DOSE,* REM 1 LOCATION WHOLE BODY THYROID BASED ON EASUREENTS STOCKHOW 0.002 0,01 (750 MI) BASED ON EASUREE NTS HELSINKI 0,005 NO DATA (700 MI) BASED ON M DELS CHERNOBYl. 7100 4000 (1 MI)

BASED ON 1-DAY EXPOSURE IN U.S.S.R,; 2-DAYS FOR SWEDEN AND FINLAND 4

i Y r e / __z- _ _.. r.- .,_.,r_ _m _.,-..-..,__-m,-, _.,.m.__..

e s PREPARE REPORT ISSUES NEED FOR EARLY WARNING SYSTEM (IAEA) s NEED FOR SYSTEM FOR RAPID INERNATIONAL DATA COLLECTION AND EXCHANGE (IAEA) SEVERE ACCIDENT LESSONS ACCIDENT RELATED ISSTS SOURCE ERM TECHNOLOGY NO PROGRAWATIC CHANGES BASED ON OUR PRESENT KNOWLEDGE AND UNDERSTANDING OF WHAT HAPPENED I e J j

~. l s 1 D l SCLA I

1 E R 2

S 4 5 1 6 This i.=.an unofficial transcript of.~a meeting of the 7 Un i t ed St a t es Nuc lear Regu l a t ory Coneni ss ion he ld on 8 5/13/86 in,the Commission's office at 1717 H Street, 9 N.W., Washington, 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 I 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 1 16 matters discussed. Expressions er opinion.in this transcript 17 do not necessarily reflect final determination ce beliefs. No 18 pleading or other paper may be,fileed with t he Ccwn i s s i on in 19 any proceeding as the result of or addressed to any statement. 20 or a r g u m r_ n t contained herein, except as t he Ccan i s s i on may 21 authorize. 22 23 24 25

1 1 UNITED STATES OF AMERICA 2 NUCLEAR REGULATORY COMMISSION 3 4 STAFF BRIEFING ON CHERNOBYL ACCIDENT 5 6 PUBLIC MEETING 7 8 Nuclear Regulatory Commission 4 9 Room 1130 10 1717 "H" Street, N.W. 11 Washington, D.C. 12 13 [ Tuesday, May 13, 1986 14 15 The Commission met in open session, pursuant to 16 notice, at 3:00 o' clock p.m., NUNZIO J. PALLADINO, Chairman of 17 the Commission, presiding. i 18 COMMISSIONERS PRESENT: 19 NUNZIO J. PALLADINO, Chairman of the Commission 20 THOMAS M. ROBERTS, Member of the Commission 21 JAMES K. ASSELSTINE, Member of the Commission 22 FREDERICK M. BERNTHAL, Member of the Commission 23 LANDO W. ZECH, JR., Member of the Commission j 24 i 25 + l

2 1 STAFF AND PRESENTERS SEATED AT COMMISSION TABLE: 2 S. CHILK 3 T. ROTHSCHILD l 4 V. STELLO l 5 H. DENTON 6 T. SPEIS 7 B. SHERON 8 F. CONGEL 9 10 AUDIENCE SPEAKERS: 11 W. SWENSON 12 13 14 15 a 16 17 18 19 20 21 22 23 1 24 25 g - r - + -3m- . -. ~ g 7 y, + + c--e,f

I t hh hhhhhhhh hph_ _ _p_ 0 g 9/35 h TRANSMITIAL TO: Docment Cbntrol Desk, 016 Phillips j e 3 ADVANO D COPY 10: / / The Public Documnt Boan ? l l 6//5/P6 9 IE DATe: 3 7 cc: C&R a c FICM: SIrY OPS BRA?Of ,p ~ papers.'

it!

Attached are copies of a Ormission neeting transcript (s) and related neeting M docunent(s). They are teing forwirded for entry on the D1ily Acx:ession List j and placemnt in the Public Document Pean. tb other distribution is requestcd j E or regtured. Existing DCS identification numbers are listed on the iniividual f B' Meeting

Title:

documents wherever krmn. f F bN9 I eo C hts-no kceOpd k _s-g g r F 4 - h

5; Meeting Date

1(p Open )( Closed t DCS Copies (1 of each checked) Iten

Description:

Copies em Advanced original May Duplicates 7b PDR Document b2 Dup

Cocv' 6

1. TRANSCRIPr 1 1 hhen checked, DCS should send a g a:py of this transcript to the F LPDR for: e/ u dear As s 3 a E p 3 e 3 4-E C E E (PDR is advanced one copy of each document,

Verify if in DCS, and 3

t'Wo of each SECY paper.) Qunge to "PDR Available." ~ F

MMMMMMMMdWMMMMMd6AWyyyyAgyyydWyyyjWyh}}

ML20197J088

Contents

Text

Title:

Description:

Navigation menu

ML20197J088

Text

Title:

Description:

Navigation menu

Search