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When 10,000 square miles of contamination is an acceptable risk: The NRC’s faulty concept via The Bulletin of Atomic Scientists

By Victor Gilinsky

In making safety decisions, the Nuclear Regulatory Commission uses accident probability calculations that are much more optimistic than anything that nuclear manufacturers like General Electric and Westinghouse actually believe. The result is weak public protection. A good example is the NRC commissioners’ rejection in 2014 of a proposal to limit the possible severe consequences of spent fuel pool fires in nuclear power plants because the proposal’s cost, however modest, exceeded the value of the expected reduction in “risk.”

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The spent fuel pool issue gained prominence after the 2011 Fukushima accident. For a time during the accident the dominant concern was that spent fuel in Fukushima’s damaged Unit 4 pool might catch fire. It didn’t happen, but it could have multiplied the effects of the catastrophic Fukushima accident manyfold. The NRC staff told the commissioners in 2014 that a worst-case spent fuel pool fire in a US plant like those at Fukushima—of which there are nearly three dozen—could release 25 times more long-lasting radioactivity than escaped from the Fukushima reactor vessels, and perhaps even more. Such a release could render 10,000 square miles uninhabitable and (around the Pennsylvania nuclear plant the staff chose as an example) could require the evacuation of 4 million persons.

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In fact, they weren’t deciding anything. The commissioners lent an air of official seriousness to the proceeding, but the decision making was on autopilot. It involved calculating the average risk (R) of an accident by multiplying two numbers, the accident’s probability (P) and its consequence (C). If P is sufficiently small, the average risk (or P times C) will be negligible no matter how large the consequence. And, therefore, the possible reduction in risk will hardly be worth any expenditure. That is how it worked in the 2014 case of a possible spent fuel fire, and that is how it has worked in most cases involving protection against severe accidents.

Actually, most cases don’t get this far. The commission has a threshold for the staff to investigate a safety issue posed by a hypothetical accident. If the estimated probability of “prompt” deaths offsite is below 2 in 1 million per year, the NRC staff need not investigate further. This involves a kind of Catch-22. The NRC assumes effective evacuation of the surrounding area in the event of an accident, so there aren’t people to be irradiated, and even substantial accidents don’t exceed the commission’s threshold.

[….]

There are several things wrong with the NRC’s cost-benefit approach to nuclear safety. To begin with, neither factor in the risk formula—probability times consequence—can be calculated with any accuracy. For example, the consequences of an accident requiring the long-term, possibly permanent, evacuation of 4 million will surely not be limited to the expense of such an evacuation. It would, for example, almost certainly spell the end of nuclear power use in the United States and likely in many countries, with huge economic consequences. We know the Fukushima accident resulted in the closing of all Japanese nuclear plants, hardly any of which have gone back into operation. The Fukushima accident cost estimate already runs into the hundreds of billions of dollars. A very much larger such accident in the United States could run into trillions. None of this is part of the NRC’s blinkered analysis.

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lso, using average risk doesn’t reflect what most people—the people the NRC is supposed to be protecting—want to achieve. They don’t want to risk losing a city, no matter what the calculated probabilities. That is how the nuclear manufacturers—Westinghouse and General Electric—see it, too. They refuse to participate in any project unless they are guaranteed to be free of any liability for any offsite accident consequences. If they believed the NRC risk calculations, they would have no difficulty in accepting the litigation risk—but they obviously don’t. In short, the organizations most highly knowledgeable about nuclear safety don’t trust the NRC’s probabilistic calculations.

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