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inter Jr. Mattson. That there had been some kind of event at Three

ether Mile Island.

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Mr. WEAVER. What time was this?

Mr. Mattson. Midmorning, Wednesday, the 28th. ek TO

Mr. WEAVER. Nine to nine-thirty? tif

Mr. Mattson. Probably closer to 10 o'clock. It would not be normal for me to be called on an operating reactors kind of problem. Mr. Stello is the Director of the Division of Operating Reactors. I am Director of the Division of System Safety. I believe I was talking to a secretary so I knew I was not getting firsthand information. I asked

her to have Mr. Denton talk to me later whenever he knew what was But **

going on.

He did that later in the day and said that the people were working hard in the incident center. He planned to go on over a little later in the afternoon and that I should keep working the five-plant shutdown. You may recall we had been down talking to you a week or so before.

The first priority for my day, that day, was working on the seismic Teher

analysis of the five plants that were down. I, in fact, stayed on that mint tork until about 2 o'clock Thursday afternoon, at which time I went PELE 10 the incident center to get Mr. Stello to sign a piece of paper having

to do with the five-plant shutdown. From that time on, I have been at is working Three Mile Island.

Mr. WEAVER, Mr. Stello, when would you say you first heard--where were you and what was happening!

Mr. STELLO. I got to work about 7, 7:30 that morning. The first phone call I received. I think, was identifying that there had been an incident at Three Mile Island, probably near the hour of 8 o'clock in the morning. Mr. WEAVER. From whom? Mr.STELLO. Mr. Moseley. Mr. WEAVER. Who is Mr. Moseley? Mr. STELLO. Mr. Moseley is the Director of all of the operating

mactors in the Inspection and Enforcement Division, who called and Ta tirated our operations center. As part of the standard procedure for

artivation of that center, he is to call the various members, and I am one of them. So he called to notify me that the center had been stivated.

Mr. Eisenhut was in the office with me that morning. I immediately 1 called Mr. Grimes, since he knew there had been a release of fission

products to the environment. I told Mr. Grimes to immediately go to

the center.

I asked Mr. Eisenhut to set up the various people that would be I needed to understand Three Mile Island in his office, and as soon as I

gave him that word I immediately left to go to the center. Mr. WEAVER. The center is Bethesda? Mr. STELLO. It is in Bethesda in our headquarters Office of Inspecion and Enforcement on East-West Highway, some distance from my office which is on Norfolk Avenue. Mr. WEAVER. How many times has that center been activated ? Mr.STELLO. I can recall, I guess, three occasions. Mr. WEAVER. Three occasions in the past?

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Mr. STELLO. This being the third. There may have been more.
Mr. WEAVER. In the past how many years?
Mr. STELLO. Since its existence.
Mr. WEAVER. Which is?

Mr. STELLO. About 3 years. Browns Ferry fire being, I think, t first one that I can recall.

Upon arriving at the center, I tried to obtain some informatic understanding about what was happening both to the reactor and the environment. We had a communications system set up, whe people who were in the control room at Three Mile Island were cor municating factual information as to what was happening to t people in Bethesda. We were doing various kinds of studies, trying understand the process that was going on in the reactor as well what was going on in the environinent.

Our immediate effort was probably heaviest in terms of understan ing what was happening to the reactor, since the normal process that you expect if you have a very bad accident in the reactor is or where the primary envelope has been breached and the water an fission products are emptied into the containment and environment.

Here we had a clearly different situation. We had an intact pr mary system with significant release of fission products. Earl throughout the day it became apparent that conditions had develope where the core was being badly damaged.

Mr. WEAVER. This is still on Wednesday!

Mr. STELLO. I am now giving a very general picture of Wednesday rather than specific hours. Without going back through the actue tapesMr. WEAVER. Surely. Mr. STELLO [continuing]. Refreshing my own recollection wit

) respect to hours or times, I could not. But throughout the day, th clear impression was created that there was significant damage being caused to the core. The principal reason I am giving you a persona feeling~I cannot remember whether the group truly felt this way or not.

Mr. WEAVER. I understand.
Mr. STELLO. I will try to come back-
Mr. WEAVER. I have to leave. Dr. Myers, proceed. I will be back.

Mr. STELLO. The reason for believing you had significant damage was the fact that we had a clear indication that there was superheated steam coming out of the reactor vessel. The only way you can, in fact. get superheated steam out of the vessel is to have the core uncovered. And the core, just from recollection, was uncovered for substantial periods of time throughout the day, which left me with the clear impression that significant damage had occurred in the core.

Dr. MYERS. Did you at the time have a sense of what you were thinking of by significant damage, whether it was as it turned out to be. Were you thinking at the time it might be as extensively damaged as it later developed it was?

Mr. STELLO. My initial reaction was that considerable failure of the fuel had occurred, with large numbers of failed fuel rods. And that the potential for oxidation, metal-water reaction, was clearly

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The periods of time involved were, even if the heat-up were not significant, at lower temperatures, with the top of the core uncovered for extended periods of time, metal-water reaction was clearly pos

sible. The rates—how high the temperature got I would not even link , indicate- I could have guessed at. But oxidation of the cladding was

something I clearly expected; failures of the cladding were clearly rmato evident.

Mr. Terrell. When did you suspect this? This is on Wednesday ), WE rou are talking about that you expected this fuel damage?

Mr. STELLO. Yes. I think just from knowing what was happening to 3 to the core, you had to expect that there was quite a bit of damage to ITING the fuel.

Mr. TERRELL. Was this communicated to anyone?

Mr. STELLO. I think yes. I think we talked about it. erstar Mr. TERRELL. To whom?

Mr. STELLO. People that were in the incident center.

Mr. TERRELL. How far did that go up? I mean did it reach the ter a Commissioners ?

Mr. STELLO. There were Commissioners present from time to time ct p/ in the incident center. Probably at one time or another I made my

Ex views known, that I expected that the core had been uncovered and Celos. the fuel damaged. I suspect so.

Mr. Reis. Was that contested? Was there a discussion as to whether

there was or was not damage during that time? Desde Mr. Stelio. I do not know of anyone who suggested there was not atz damage to the core. I guess I am confused—maybe there is a history

of something that had gone on which suggested - I do not know why you are asking the question.

Mr. Mattson. I do not know how anybody could contest that quesr.tttion because there are fission products all over the place. That is genbenerally accepted and known and they only come from failed fuel. So ro... by definition there is some core damage. The extent of the core damage s mas subject to further information and further conjecture, I suspect,

in a number of people's minds.

Mr. STELLO. If you are asking me the question which there is something behind I could get to-I just do not know of any reason any

body would have contested it. I think the people who were there genmis erally knew there was damage to the core. I do not know of anyone

who would have argued to the contrary. The early concern was what I could we possibly do to advise the licensee as to how to try to correct

the situation since you had, as I indicated before, an arrangement which is not what you would normally have expected if you had an acident with a lot of fission product release, which is a broken primary boundarv.

You clearly had an intact primary boundary with the system pres

sure having varied from 2.000 pounds per square inch down to 450 or daryl 50 pounds per square inch on backup to in excess of 2,000 pounds per

square inch. So clearly, you had an intact primary boundary.
Norr, how to deal with the situation was one of concern.
Mr. Rers. Intact except in the sense of the valve?
Mr. STELLO. They were able to correct that by closing a block valve.
l'ou knew you had a primary boundary that was in good shape in
terms of holding the coolant.

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Mr. SCOVILLE. We are jumping around here a good bit, which part of the nature of the informality of it. Perhaps we could fox inore and stick to the point. I think if we returned to the chronolo of the event as each of you understand it.

Mr. STELLO. I was trying to do that.

Mr. SCOVILLE. I understand. I am not being critical. But I thi we should proceed in that order and we can probably keep our ey on the ball.

So to go back to that, you were about to defer to Mr. Eisenhut discuss the chronology, or were you discussing your person involvement ?

Mr. STELLO. I was discussing my personal involvement which about all I can do to identify the chronology.

Mr. SCOVILLE. OK.

Mr. STELLO. Other than that, why, without going back and goii through the records, I would be hard pressed to put times against the things.

Dr. MYERS. The briefings have been presented to the Commissio So I think Darrell has done that. Is that possible to sort of ru through the major events as you understand them, starting with t? initial malfunctions ?

Mr. EISENHUT. Sure.

Dr. MYERS. I think there are certain details of this that maybe ai not well understood now. But I think maybe that is not so importar for this discussion, but to say that these are the major events tha happened along the way, and this is what people did, and maył interjecting here and there where you think they might have don something different would be useful.

Mr. SCOVILLE. Before you start that, because it is going to tak quite some time, there are a couple of points involving what you wer doing in the response center as to whether one particular topic wa mentioned. I think maybe the answer would be fairly simple. W could get it on the record and go back to it again. That is, as I under stand it, you were at the response center on Wednesday.

To your knowledge, did anyone mention to you the possibility of: hydrogen burn or detonation within the containment at Three Mil Island that day, that it may have occurred? Do you remember that

Mr. STELLO. I do not recall any specific discussion of a hydrogei burn inside the containment. But there was considerable discussior that hydrogen evolution would be taking place with a metal-wate: reaction. But I do not recall ever hearing that there was a hydroger burn. So the answer is I have no recollection of hearing that or Wednesday. I think Friday was the first time I heard it.

Mr. SCOVILLE. Mr. Mattson, you were at the incident response cen: ter, as I understand it, Wednesday afternoon?

Mr. MATTSON. Thursday afternoon.

Mr. ScoVILLE. I missed it. OK, I need not ask you the question except to ask you when was the first time you heard about the possibility of a hydrogen detonation or hydrogen burn?

Mr. MATTSON. Approximately 10 a.m. Friday, the 30th.

Mr. SCOVILLE. Then the other question is: What about the report-**** ing of a pressure spike in the control room indicating increased presa

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Mr. Mattson. I should correct my answer. I heard of the spike, uld by pressure spike, at about 10 a.m. on Friday morning, the 30th, from romake which we conjectured that there had been a hydrogen explosion.

Mr. Reis. Was that conjecture immediate? If you heard of a spike in containment, would your trained mind immediately go to

Mr. Mattson. Mine did, yes. Mr. STELLO. If it is a spike—the thing that I saw on the chart finally would be something that identified with a sudden release of energy such as a hydrogen burn. I could not think of anything else, so I would have that association. Mr. SCOVILLE. When did you learn of the spike? Mr. STELLO. To me the spike has now become synonymous with

the hydrogen burn. No longer is it separable in my mind—they are ਕੀ "

one and the same and the answer is the same-Friday morning. Although there could be—and again I would have to go back and check—we did know that sprays came on. I am trying to remember, when did we know the sprays came on? I thought we knew they

came on Wednesday or Thursday. of

Mr. EISENHUT. Yes. Mr. STELLO. Which would mean we knew that the pressure had to go over 5 psi. Mr. EISENHUT. Four or five. Mr. STELLO. Four or five. I do not remember following that up in any great detail.

Mr. TERRELL. Would that imply in the slightest sense that there
was a significant buildup of hydrogen in the containment building?

Mr. STELLO. It would imply that the containment pressure had to
be raised above the set point for the system.
Mr. TERRELL. What could have caused that phenomenon?
Mr. STELLO. Without going back and checking through the records,

I could recall that containment pressure had been rising. I do not BA

remember whether it had been getting close to the set point by itself. Mr. EISENHUT, No.

Mr. STELLO. Or whether you would have had to have something To like the hydrogen burn. ON

Mr. TERRELL. I just wonder if there could have been other phe

nomena that could have created the situation other than hydrogen. Im Mr. STELLO. Yes.

Mr. Eisenhut. Let me try to bridge the gap for a second. As Vic seid, we took the phone call Wednesday morning. I got together a

group of technical people at our office. In fact, we were running a stimuple different groups, one on radiological aspects, one on systems

performance. I went to the incident center on Wednesday afternoon. e I share Mr. Stello's view that there certainly was not any real dis

mresion, that I can recall either, of spikes in the containment on Wednesday. It seems like there may have been probably-time runs to

gether because we were there essentially on a 24-hour basis. Either late pon Thursday or Friday morning, there was considerable discussion

about how fast the spike was. If, in fact, it was a very rapid spike, it would be disociated logically with something like a hydrogen burn. The pressure in the containment I know we had been monitoring and were following. It was varying anywhere from 2 to 4 psi and, in fact, appeared

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