Looking Back: Hearing on Lessons Learned from Three Mile Island

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Publication date: 
20 April 2009

“There is no doubt that the accident at Three Mile Island permanently changed both the nuclear industry and the NRC.” - Nuclear Regulatory Commission

Thirty years after the most serious nuclear accident in the history of the U.S. commercial nuclear power industry, a Senate subcommittee  held a hearing to examine the lessons learned from the partial meltdown of the reactor core in one of the two units of the Three Mile Island Nuclear Power Plant outside of Harrisburg PA.

The main feed water pumps at TMI-2 stopped working early in the morning on March 28, 1979.   For five days, anxiety grew as plant operators and federal officials came to realize the severity of this accident entailing the partial meltdown of the unit’s reactor core and the resulting large hydrogen bubble.  Although this accident caused no deaths or injuries, and resulted in only, according to the NRC, “very small off-site releases of radioactivity,” Three Mile Island altered the public’s confidence in the nuclear power industry.  For 28 years no new nuclear plant application was filed with the NRC.  That has now changed, as 22 applications have been docketed and are now undergoing the commission’s review for 33 new units .

The Senate Subcommittee on Clean Air and Nuclear Safety received testimony from two panels of witnesses at this March 24 hearing.  Almost all of the testimony from the first panel of NRC witnesses and the second panel of private individuals focused on changes that were made in procedures and communications, with much less discussion of technical or engineering matters.

One of the major lessons learned was repeatedly discussed by the witnesses: the need to guard against complacency.  NRC Commissioner Gregory Jaczko cited a finding from the 1980 Rogovin Report:

"we found that before March 28, 1979, an attitude of complacency pervaded both the industry and the NRC, an attitude that the engineered design safeguards built into today's plants were more than adequate, that an accident like that at Three Mile Island would not occur – in the peculiar jargon of the industry, that such an accident was not a 'credible event.'"

Jaczko added, “I think that is a statement that can be as true for us today as it was in 1979 . . . in the sense that those are the lessons and the things we need to keep our focus on as regulators.”

Subcommittee chairman Thomas Carper (D-DE) touched on this same point in his opening statement, saying TMI was a “wake-up call that we had become complacent on nuclear safety.”  He spoke of sweeping changes undertaken by the NRC and the nuclear power industry and how it now has “one of the best safety records of . . . any industry in the United States.”  Carper said “we’re going to need nuclear power” because of concerns about climate change, dependence on foreign energy, and harmful emissions.  But, he warned, “broad support for the nuclear industry will vanish if another nuclear accident occurs.”  Senator James Inhofe (R-OK) and George Voinovich (R-OH) agreed with Carper’s contention that nuclear energy will be a necessary component of America’s energy future.

NRC Chairman Dale Klein spoke of wide-ranging safety improvements the commission has instituted in many areas to build what he called a “strong safety culture.”  “With all this, however, the NRC still faces one ongoing challenge which is something that confronts every industry and every regulator . . . the danger of complacency.”   Other commissioners discussed the importance of recognizing human beings as an important component of the safety system, and the interface between the operator and reactor.

Carper asked Klein how the NRC guards against complacency; Klein described training programs and other procedures to remind people about their self-responsibility and  importance.  Later in the discussion, Klein described a fundamental NRC restructuring to establish separate offices for new reactors and reactor regulation.  NRC has made strides in emergency preparedness, and in encouraging information sharing among all parties both within the United States and internationally.  Klein stressed the importance of standardization in nuclear plant designs for regulation and efficiencies, saying “I want the walls even to be painted the same colors.”

Avoidance of complacency was stressed by witnesses on the second panel, with Marvin Fertel,  CEO of the Nuclear Energy Institute describing the formation of an Institute of Nuclear Power Operations only nine months after the accident.  One of his key points echoed that made by all the other witnesses: “One of the nuclear industry’s tenets is to never . . . become complacent.”