Severe 5-Day Atomic Reactor Loss-of-Coolant-Accident at Three Mile Island, March 1979
October 30, 2018   [laptop-built, view on narrow browser window]

Control-Room Disorganization During Sudden Loss-of-Coolant
Accident/Core-Meltdown at TMI Unit II Atomic Reactor March 1979

"...the streets were barren... people were fleeing, literally, the city." Harold Denton, NRC Regulator

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(1) Harold Denton, Director of the Office of Nuclear Reactor Regulation, Nuclear Regulatory Commission, appointed by President J. Carter to direct operations at the Three-Mile-Island Unit II Nuclear Reactor:

"He found the power plant to be in 'absolute chaos,' he told The Washington Post at the time. He brought in as many as 100 scientists to examine the facility, and a special phone line was installed, connecting Mr. Denton directly to the White House."

  • See also:
"We are operating almost totally in the blind; his [Pennsylvania Governor Dick Thornburgh] information is ambiguous, mine is nonexistent and —I don't know — it's like a couple of blind men staggering around making decisions."[italics added]
Joseph Hendrie [Commissioner, Nuclear Regulatory Commission]: Commissioners Deplored a Lack of Information, Meeting Records Show: New York Times, April 13, 1979

"Let me say, as frankly as I know how, bringing this plant down is risky. There's a not negligible risk in bringing this plant down. No plant has ever been in this condition, no plant has ever been tested in this condition, no plant has ever been analyzed in this condition in the history of this program.
Roger Mattson [Director, Nuclear Regulatory Commission Division of System Safety] Excerpts From Nuclear Mishap Talks: New York Times, April 14, 1979

"It's too little information too late unfortunately, and it is the same way every partial core meltdown has gone. People haven't believed the instrumentation as they went along. It took us until midnight last night to convince anybody that those goddamn temperature measurements meant something...."

"...my principal concern is that we have got an accident that we have never been designed to accommodate..." [italics added]
Roger Mattson {Director, Nuclear Regulatory Commission Division of System Safety] Ibid.

"'What was the situation there, when you arrived? What did you find?'

Harold Denton [NRC]: 'Uh, pretty chaotic situation in the observation center. No one really knew what was going inside the reactor containment...' They had hundreds of thousands of gallons of water in the containment building floor, they had 50,000 gallons in the auxiliary building floor, tanks were overflowing, drains were overflowing, instruments were off scale due to the magnitude of the release..."

"...the fact that the streets were barren... people were fleeing, literally, the city."

"By Saturday I had 75 people from the NRC staff at the site... I got the company [Med-Eed] to agree that they would make no changes without our concurrence... [Mr. Denton details a list of other power companies who agreed to come onboard] "Eventually, I think the entire US industry was represented... There were people there from GE and Westinghouse, as well as B&W [Babcock & Wilcox], the designer."

"I think in any emergency, it would be well to get the president involved...to prompt action."
Video from the office of Governor Richard Thornburg (in)
Harold Denton: Lessons from Three Mile Island: June 21, 2011

"When I came to work Friday morning, there were a lot of indicators that there'd been severe core damage... There were extremely high radiation levels in a large part of the plant...

"The control room only had 2 telephones. And it was very difficult to get through to the company. The press were beginning to ask a lot of questions, and trying to dial the control room at the same time we were trying to dial the control room. And if you ever got an operator in the control room, you said: 'Please don't hang up!'"
-Harold Denton: Lessons from Three Mile Island: June 21, 2011

"The accident at Three Mile island was not only unexpected, it was a dilemma no state government had ever faced before. Together, they [Pennsylvania Governor Richard Thornburg & his team] confronted a utility company that was unable or unwilling to explain just what was going on." [italics added]

Video from the office of Governor Richard Thornburg (in)
-Harold Denton: Lessons from Three Mile Island: June 21, 2011

"The company was giving us conflicting statements. And it did not take us too long to find out that they were failing either intentionally, or unintentionally, to tell us the whole story."

Governor Thornburg's Press Secretary, Ibid.

"The principal concern we've had throughout this whole process is to get the facts. Because any over-reaction, or counter-productive reaction has enormous consequences. This is a totally unique event..."[emphasis in original]

Pennsylvania Gov. Richard Thornberg, ibid.

  • See also:

"At 3:55 a.m. on March 28, 1979, people living near the Three Mile Island nuclear power plant about a dozen miles from Harrisburg, Pa., were awakened by a loud roar that 'shook the windows, the whole house,' in the words of one resident.

"Within hours, alarm sirens sounded inside the facility, as workers struggled to understand what was happening. Harold Denton, the country’s leading authority on nuclear safety, was summoned from a meeting at Nuclear Regulatory Commission headquarters and told that a 'relatively serious sort of event' had occurred...

"Telephone lines were overburdened, making communications between Three Mile Island and Washington difficult. NRC Chairman Joseph Hendrie said he and Pennsylvania Gov. Richard Thornburgh were 'operating almost totally in the blind. His information is ambiguous, mine is nonexistent.'

"Mr. Denton was monitoring events from NRC’s headquarters, but President Jimmy Carter said a federal official should be at the scene to take charge. On March 30, two days after the initial accident, Mr. Denton flew to Three Mile Island in a White House helicopter.

"He found the power plant to be in 'absolute chaos,' he told The Washington Post at the time." [italics added]

Harold Denton, nuclear regulator who calmed fears at Three Mile Island, dies at 80: Washington Post https://www.washingtonpost.com/national/harold-denton-nuclear-regulator-who-calmed-fears-at-three-mile-island-dies-at-80/2017/02/21/e3ac577c-f527-11e6-8d72-263470bf0401_story.html?utm_term=.3b49a8ce73a2
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  Commissioners Deplored a Lack of Information, Meeting Records Show: New York Times, April 13, 1979: "WASHINGTON, April 12 — In long, secret meetings in the first days after the accident at the Three Mile Island nuclear power plant, some members of the Nuclear Regulatory Commission expressed fear that the 'horse race' against a calamity might be lost. ...

"On Friday, March 30, the third day of the crisis, the commission chairman, Joseph M. Hendrie, said of the problems facing him and Gov. Dick Thornburgh of Pennsylvania: 'It seems to me I have got to call the Governor. We are operating almost totally in the blind; his information is ambiguous, mine is nonexistent and —I don't know — it's like a couple of blind men staggering around making decisions.'

"The drama and confusion of those days came to life today in more than 800 pages of transcripts from closed commission meetings that were given to three Congressional subcommittees.

"..the five commissioners and the agency's technical staff were, at times, near despair because of sketchy information about the reactor and the difficulty of evaluating unforeseen events. Repeatedly, they discussed the possible disasters involving a core meltdown or a gas explosion that might have spilled large, lethal doses of radioactivity into the countryside..

"Describing extensive damage to the reactor core to the commissioners on March 30, Roger J. Mattson, the director of the division of systems safety, said, 'We saw failure modes the likes of which have never been analyzed.""Do we win the horse race or do we lose the horse race?' he asked in discussing how to remove the [Hydrogen] bubble.

"...N.R.C. nearly recommended an evacuation out to five miles downwind after a plume of radioactive gas was vented Friday morning. 'The latest burst didn't hurt many people,' Mr. Mattson said in the Friday meeting. 'I'm not sure why we're not moving people. Got to say it, I have been saying it down here: I don't know what we are protecting at this point, I think we ought to be rnovin[sic] people.'

".. But Dr. Hendrie has since explained in Congressional testimony that the early calculations on the evolution of oxygen in the reactor, which suggested a flammable or explosive mixture, were in error. However, in the early days after the accident, the question caused great alarm.

"At one point, Mr. Denton expressed concern that plant officials were net[sic] providing clear information. 'It is really difficult to get that data,' he said. 'We seem to get it after the fact.'" [italics added] http://www.nytimes.com/1979/04/13/archives/commissioners-deplored-a-lack-of-information-meeting-records-show.html

"For Dick Thornburgh, Three Mile Island was a 'searing first experience.' He was just 72 days into his first term as Pennsylvania governor when the incident began to unfold. He says the plant owner and operators initially told him that "all the systems had worked, and there was no danger." And Thornburgh relayed that information to anxious Pennsylvania residents."

"'That was clearly a misrepresentation, as our own engineers and nuclear regulatory people could see at the site,' says Thornburgh, who later served as attorney general under presidents Ronald Reagan and George H.W. Bush. "'Clearly I was a lot more skeptical after that. ... If you pass on some bad information, you better get out and get in front of it.'

"Ironically, Thornburgh says admitting that he had put out bad information ultimately helped his credibility." [italics added]
Nuclear Information Gap Spreads Doubt, Fear: NPR, March 16, 2011

  • See also:
Excerpts From Nuclear Mishap Talks: New York Times, April 14, 1979. "WASHINGTON, April 13 — The accident at the Three Mile Island nuclear station began on Wednesday, March 28. But for the first 48 hours the Federal agency responsible for assuring the safety of the reactors was reasonably confident that the public was not seriously endangered....

"But on Friday, March 30, engineers of the Metropolitan Edison Company released a plume of radioactive material into the atmosphere from the crippled plant. Partly because of this release of radioactivity and partly because some of the commission's top officials had reached the scene of the accident, the commission's view of the problem became far more pessimistic.

"Beginning shortly after 9 A.M. March 30, the five members of the commission began a long and extraordinary series of formal meetings in which they attempted to understand what was occurring within the seriously damaged reactor, what the possible consequences might be, what recommendations they should make to Pennsylvania Gov. Dick Thornburgh and how they should deal with the public, the press and the White House.

"The following are excerpts from the sometimes highly technical conversations of these and other officials as they struggled with the worst accident in the history of the commercial use of nuclear power...

[Friday, March 30] "MR. DENTON: Yes, I think the important thing for evacuation to get ahead of the plume is to get a start rather than sitting here waiting to die. Even if we can't minimize the individual dose, there might still be a chance to limit the population dose.

"MR. HENDRIE: It seems to me I have got to call the Governor.

"MR. FOUCHARD: I do. I think you have got to talk to him immediately...

"MR. THORNBURGH: Do we have any assurances that there is not going to be any more of these releases?...

"MR. HENDRIE: No...

"MR. MATTSON: It's too little information too late unfortunately, and it is the same way every partial core meltdown has gone. People haven't believed the instrumentation as they went along. It took us until midnight last night to convince anybody that those goddamn temperature measurements meant something. By 4 o'clock this morning, B.&W. [The Unit II Atomic Reactor designers, Babcock and Wilcox] agreed.

"MR. MATTSON: We are still doing analyses with what we now understand the conditions, to see if we can try to estimate with the codes, what the condition of the core really is. It is a failure mode that has never been studied. It is just unbelievable.

"MR. GILINSKY: What is your principal concern right at this minute?

"Mr. MATTSON: Well, my principal concern is that we have got an accident that we have never been designed to accommodate, and it's, in the best estimate, deteriorating slowly, and the most pessimistic estimate it is on the threshold of turning bad.

[Saturday, March 31] "At the long commission meeting the next day, Saturday, March 31, the transcripts indicate, the members were still seriously concerned about the possible consequences of the accident, including a core meltdown."

"...And what happens then is you've now got a noncondensable gas evolution at substantial rate into the containment; the containment pressure goes up, you're going to come to a point eventually where you either vent the containment — you've got your choice, then, you can either vent the containment or you can let it go on up past the design pressure and probably somewhere on beyond a factor of two above design, why you'll blow something out...

"COMMISSIONER BRADFORD: I mean, is it at all likely that there is a sequence of events that could start anytime without warning which would leave you with substantially less than 200 minutes or six hours or whatever number on that order you want to use to have people more than five or 10 miles away.

MR. HENDRIE: I don't think it's a very large possibility but you can't rule it out.

"COMMISSIONER KENNEDY: What would the nature of the sequence be?

"MR. HENDRIE: A hydrogenn[sic] explosion in the vessel...

"MR. MATTSON: Let me say, as frankly as I know how, bringing this plant down is risky. There's a not negligible risk in bringing this plant down. No plant has ever been in this condition, no plant has ever been tested in this condition, no plant has ever been analyzed in this condition in the history of this program.

"By Monday and Tuesday, the commission gradually began to feel that the operators of the crippled reactor. the hundreds of outside experts that had been assembled to consider various aspects of the accident and the N.R.C. staff had managed to bring the situation almost under control." [italics added]
http://www.nytimes.com/1979/04/14/archives/excerpts-from-nuclear-mishap-talks-complaint-from-governor.html

  • See also:
Report of the President's Commission on the The Accident at Three Mile Island, October 1979, John Kemeny (President, Dartmouth College), Chairman.

"Over 100 alarms went off in the early stages of the accident with no way of suppressing the unimportant ones and identifying the important ones. The danger of having too many alarms was recognized by Burns and Roe during the design stage, but the problem was never resolved....Some key indicators relevant to the accident were on the back of the control panel.

"A shift supervisor testified that there had never been less than 52 alarms lit in the control room."

"Several instruments went off-scale during the course of the accident, depriving the operators of highly significant diagnostic information. These instruments were not designed to follow the course of an accident... The computer printer registering alarms was running more than 2-k hours behind the events and at one point jammed, thereby losing valuable information.

"Fourteen seconds into the accident, an operator in TMI-2's control room noted the emergency feed pumps were running. He did not notice two lights that told him a valve was closed on each of the two emergency feedwater lines and thus no water could reach the steam generators. One light was covered by a yellow maintenance tag. No one knows why the second light was missed.

Frederick and Faust (Unit II TMI Atomic Reactor control room operators] were in the control room when the first alarm sounded, followed by a cascade of alarms that numbered 100 within minutes. The operators reacted quickly as trained to counter the turbine trip and reactor scram. Later Faust would recall for the Commission his reaction to the incessant alarms: "I would have liked to have thrown away the alarm panel. It wasn't giving us any useful information."

"During the most critical phase of the accident, the NRC was working under extreme pressure in an atmosphere of uncertainty. The NRC staff was confronted with problems it had never analyzed before and for which it had no immediate solutions.

"... the control room crew. They later described the accident as a combination of events they had never experienced, either in operating the plant or in their training simulations.

"After an incident at TMI-2 a year earlier during which the PORV stuck open, an indicator light was installed in the control room. That light showed only that a signal had been sent to close the valve -- it did not show whether the valve was actually closed -- and this contributed to the confusion during the accident.

"The accident got sufficiently out of hand so that those attempting to control it were operating somewhat in the dark. While today the causes are well understood, 6 months after the accident it is still difficult to know the precise state of the core and what the conditions are inside the reactor building. Once an accident reaches this stage, one that goes beyond well-understood principles, and puts those controlling the accident into an experimental mode (this happened during the first day), the uncertainty of whether an accident could result in major releases of radioactivity is too high...

"In an interview with the Commission staff, Mattson [Roger Mattson, director of NRC's Division of Systems Safety described what happened next:

'And Stello tells me I am crazy, that he doesn't believe it, that he thinks we've made an error in the rate of calculation...Stello says we're nuts and poor Harold is there, he's got to meet with the President in 5 minutes and tell it like it is. And here he is. His two experts are not together. One comes armed to the teeth with all these national laboratories and Navy reactor people and high faluting PhDs around the country, saying this is what it is and this is his best summary. And his other [the operating reactors division] director, saying, "I don't believe it. I can't prove it yet, but I don't believe it. I think it's wrong."'

"Throughout the first week of the accident, there was extensive speculation on just how serious the accident might turn out to be...There was very extensive damage to the plant.

"Whether in this particular case we came close to a catastrophic accident or not, this accident was too serious. Accidents as serious as TMI should not be allowed to occur in the future...

"Although NRC personnel were on-site within hours of the declaration of a site emergency and were in constant contact with the utility, the NRC was not able to determine and to understand the true seriousness and nature of the accident for about 2 days, when the fact of extensive core damage and the existence of the hydrogen bubble were generally recognized within NRC.

"During the first 2-1/2 days of the accident, communications between the NRC Incident Response Center in Bethesda, Maryland, where the senior management was located, and the site were such that senior management officials found it extremely difficult to obtain up-to-date information.

Communications were so poor on Friday morning that the senior management could not and did not develop a clear understanding of conditions at the site...

"As long as proposed improvements are carried out in a 'business as usual' atmosphere, the fundamental changes necessitated by the accident at Three Mile Island cannot be realized.

"In addition to all the other problems with the NRC, we are extremely critical of the role the organization played in the response to the accident. There was a serious lack of communication among the commissioners, those who were attempting to make the decisions about the accident in Bethesda, the field offices, and those actually on site. This lack of communication contributed to the confusion of the accident. We are also skeptical whether the collegial mode of the five commissioners makes them a suitable body for the management of an emergency, and of the agency itself...We found serious managerial problems within the organization. These problems start at the very top." [italics added]
http://www.threemileisland.org/downloads/188.pdf

  • See also:
"Here we were, 4 days, plus a couple of hours after the accident...Just outside the front gates, Victor Stello and Roger Mattson were frantically reviewing the explosion theory. For 2 days, Stello had struggled to prove Mattson wrong. Finally, in the late afternoon, Victor Stello found the flaw in Mattson's calculations.

"They were using the wrong formula. The hydrogen bubble was never a threat. What puzzles me is how many people, not just at the NRC, not just at Three Mile Island, but people in the industry on the phone as tehnical consultants, technical consultants on site, how many of them dealt with that formula - and nobody noticed." [italics added]
The Incredible History Of Three Mile Island Documentary - 2017, 14 August 2017 45:10-46:09 https://www.youtube.com/watch?v=KXVDjhDct68

  • See also:
A top Sandia Labs analyst, Alan Swain, conducted human reliability studies "collecting human performance data for the Sandia Human Error Rate Bank...primarily in connection with supporting the reliability of nuclear weapons assembly in the US." Later Dr Swain participated in a "WASH-1400" report and on control room disorganization during rare atomic reactor events, and his findings are also remarkable.

Swain used the term "incredulity response" to describe the reaction of control room operators to an extremely rare nuclear event. For example, among his findings, Swain estimated that in the first minute following a Loss of Coolant Accident (which TMI was), the control room disorganization can become so intense that 9 out of 10 actions taken by control room operators would be wrong.

  • See also:
"Three years later, a robotic camera was lowered into the core. It would be the first look at the full extent of the accident.

"Five feet of the core was gone. That's when we really saw that the core had been severely damaged.

"We had a meltdown at Three Mile Island. It was not the China Syndrome, but we melted the core down. 50% of the core was destroyed, or molten. And something on the order of 20 tons of uranium found it's way by flowing, in a molten state, to the bottom head of the pressure vessel. That's a core meltdown. No question about it."[Roger Mattson, Director, Division of Systems Safety, Nuclear Regulatory Commission] [italics added]

The Incredible History Of Three Mile Island Documentary - 2017, 14 August 2017 48:32-49:51. https://www.youtube.com/watch?v=KXVDjhDct68

  • See also:
"One other one that's really worth mentioning, is this particular valve [PORV valve] which had failed at TMI, and actually failed 11 times before!...was unaware of it because there was no data-sharing among the utilities. They were sort of individual fiefdoms."

"The thing that is now done is...any component is immediately catalogued and sent out to all the reactors. And now it's gone worldwide..."

"I should mention that it [TMI] had at least 5 big investigations. The president appointed an investigation [the Kemeny Commission]. They produced an excellent series of volumes. Took about 6 months. The [U.S.] Senate and House both had investigations... The NRC of course did it..." [italics added]
Harold Denton [NRC onsite official at TMI Unit II reactor emergency meltdown]
Video from the office of Governor Richard Thornburg (in)
Harold Denton: Lessons from Three Mile Island: June 21, 2011

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