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How Fukushima Challenged a Core Tenet of U.S. Nuclear Safety: An Expert's View

"Nuclear power is an unforgiving technology," says Peter Lam, nuclear safety expert, whose thinking was changed by Japan's disaster.

Jul 16, 2012
The Diablo Canyon Nuclear Power Plant at Avila Beach in San Luis Obispo County,

Peter Lam's resume reflects a lifetime of experience in the nuclear energy industry–including 20 years in the private sector, followed by 18 years as an administrative judge at the U.S. Nuclear Regulatory Commission.

He's a retired nuclear engineer with 110 published judicial decisions and more than 70 technical papers in industry journals and company publications. And he's considered an international expert on nuclear reactor safety and risk assessment strategies.

So nuclear opponents were stunned last year, when Lam revealed how the Fukushima Daiichi meltdown had changed his views on the importance of accident probabilities—a key tenet of America's nuclear safety policy.

In a presentation before the California Energy Commission in July 2011, Lam raised questions about the NRC's reliance on "likelihood calculations" to guide its safety and plant design regulations. He said the industry practice of not planning for statistically improbable accident scenarios—like the disasters that struck Fukushima—could be catastrophic and needed to end.

Peter LamPeter LamThe Fukushima calamity involved two of the industry's five most dangerous but "extremely unlikely" nuclear events, Lam said. It also included multiple nuclear reactor core meltdowns—a "Black Swan" scenario never contemplated because it was deemed impossible.

"Probability dismissal is not an exact science. By [using] it, one can be very, very wrong," Lam told the commission.

The frankness of Lam's post-Fukushima assessment surprised and impressed Rochelle Becker, executive director of the Alliance for Nuclear Responsibility, a California group focused on nuclear power plant cost and reliability issues.

"I was absolutely amazed. This was not a man who I ever thought would say anything like that," said Becker. "He was a firm believer in probabilistic risk assessment until Fukushima, and he changed his mind."

Lam elaborated on those views in a March paper, where he endorsed beefed up oversight and safety enforcement and warned that "a simple dismissal [of extreme accidents] based on seemingly valid analysis should not be relied upon again."

His apparent willingness to reassess long-held industry beliefs convinced Becker to write a letter earlier this year supporting Lam's reappointment to the Diablo Canyon Independent Safety Committee. That panel has kept watch over the Central California nuclear plant since 1990. Lam was recently named committee chairman and confirmed to serve a second three-year term.  

The committee is made up of three industry experts, and it has sometimes been criticized by Becker and others as toothless and too cozy with Diablo Canyon operator Pacific Gas & Electric Co. But Lam, 65, has thus far displayed a judicial temperament more open to opposing arguments and evidence. Recently, the California attorney general's office discussed the possibility of adding a similar committee to focus on San Onofre, the troubled nuclear plant in Southern California. 

In a telephone interview, Lam talked about his post-Fukushima views on the risks of nuclear power plants, the Diablo Canyon Independent Safety Committee and whether a similar committee would be useful for communities near other nuclear plants.  

ICN: Fukushima has galvanized concerns about the safety of nuclear plants in the United States and around the world. What was your reaction when it happened? 

Lam: One can plan for a lot of things, but things don't always happen according to what you plan for. ... Sure, I think everybody's doing the right thing globally to make sure if we're hit by a major earthquake, things don't collapse on us, and if we're hit by an earthquake followed by a tsunami, electrical equipment does not get wiped out.

But I also caution everybody ... let us make sure we are not fighting the last war. The next time we are surprised by a major nuclear reactor accident, it may not be a tsunami. Therefore, let us go back and look, and look, and look to see what else is out there. Nuclear power is an unforgiving technology. Everybody needs to recognize that.

ICN: When you look at a nuclear plant now, how do you assess risk?

Lam: I don't speak for my colleagues [on the safety committee] ... but in my opinion, there are only two ways. One is called deterministic. The other one is probabilistic. I, for one, use both.

Deterministic [risk assessment] is saying, to the extent possible, one should preset a lot of parameters for how to design, manufacture, install, operate and maintain the plant. These parameters should be predetermined from day one. That is the old way the U.S. NRC regulated [nuclear plants].

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