Nuclear power safety: Latest on Japan crisis fuels new concern in US

As the nuclear plant crisis in Japan reveals more vulnerabilities in facility operation and design, calls are being renewed to change the way nuclear plants are evaluated and regulated in the United States.

Just a week ago, officials at the US Nuclear Regulatory Commission reported that America's nuclear plants are safe, noting that some gaps had been addressed or were being addressed as a result of an initial safety review to apply lessons learned from the tsunami-stricken Fukushima Daiichi nuclear plant.

Up to that point, the Fukushima facility had experienced an alarming string of crises: partial core meltdowns, station blackout, exhausted backup batteries, hydrogen explosions, fires in spent-fuel pools, failed cooling systems, and radioactive water and air released to the environment. In the US, 23 reactors have the same design as those at Fukushima. But NRC regulators assured the public last week that those reactors had been updated with special safety equipment. "Hardened vents" on the reactors would prevent a hydrogen buildup and explosion, they noted.

Since then, however, the news from Fukushima has gotten worse. On Sunday, Tokyo Electric Power Co. said the uranium fuel core in its No.1 unit had melted completely – a worse condition than previously believed – and apparently seared a hole in the reactor vessel. Core meltdowns at the No. 2 and No. 3 reactors also are more serious than earlier believed.

Then, on Tuesday, The New York Times reported that the Fukushima reactors had the same hardened emergency vents that NRC officials had said made similar plants in the US safe from hydrogen explosions. The newspaper also reported, in a separate story, that the NRC had been warned years ago that the vents were subject to failure in a crisis.

On Thursday, critics pounced.

The antinuclear group Beyond Nuclear charged that, while some US Mark I reactors possess the same venting systems that failed in Japan's crippled plant, the NRC knows that other Mark I reactor operators may not have installed – or may even have uninstalled – those venting systems. (NRC officials insist all such reactors are equipped with the vents.) If the venting systems at Fukushima Daiichi had worked as designed, they would have prevented damage to containment from the hydrogen explosions, it said.

"The NRC left the retrofit of this experimental venting system to the voluntary discretion of the US reactor operators,” said Paul Gunter, director of reactor oversight at Beyond Nuclear, in a statement. “Now that this experimental containment vent is demonstrated to have failed at Fukushima, we need to know who installed it at US plants, who didn’t, and the justification for the continued operation of these deeply flawed and dangerous reactors."

Other nuclear watchdogs say tougher US scrutiny of nuclear power is needed at every level – from approval of reactor designs, to licensing of operators, to relicensing of older reactors, to letting nuclear reactors operate at higher outputs.

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