An IAEA team reviewing the Japanese accident issued a preliminary report this week stating that Japan had underestimated the danger of tsunamis and had not provided adequate backup cooling systems at the Fukushima Daiichi nuclear complex.
"The operators were faced with a catastrophic, unprecedented emergency scenario with no power, reactor control or instrumentation," the report says. The tsunami also "severely affected communications systems both within and external to the site."
Emergency workers "had to work in darkness with almost no instrumentation and control systems," the report says.
The team said that Japan must ensure that "regulatory independence and clarity of roles are preserved in all circumstances," echoing criticism that close associations between Japan's nuclear regulators and industry officials had undermined strong safety oversight.
Mattson said he believes the IAEA meeting will look at the results from its inspection team and will probably set a schedule for further reviews and recommendations over this year. "My hope is that they will really open this question of international oversight," he said.
An initial inspection report on U.S. reactors by the Nuclear Regulatory Commission last month found that about one-third had some vulnerabilities to extreme emergencies, according to the NRC.
"Our inspectors found all the reactors would be kept safe even in the event their regular safety systems were affected by these events, although a few plants have to do a better job maintaining the necessary resources and procedures," said Eric Leeds, director of the NRC's Office of Nuclear Reactor Regulation.
Bracing for coincidental failures
Inspection reports disclosed that on one reactor, some door seals that were not hardened to withstand seismic shocks could fail in an earthquake, allowing water to enter rooms containing electrical equipment used to shut down the plant.
Another reactor had sump pumps and flooding detectors that were considered "non-safety related" and thus not hardened to withstand earthquakes, the NRC staff reported. Firefighting equipment at the reactor staged to respond to severe fires or explosions was not stored in hardened buildings because a severe fire and an earthquake "were not assumed to occur coincidentally."
A third plant had a single diesel-driven pump to provide emergency cooling water to a single reactor in case an earthquake cut off normal water flow. The pump could not have serviced both of the plant's reactors if they lost normal water supply simultaneously, the NRC staff said. The plant owner planned for a contractor to provide seawater for emergency cooling, but had no backup plan if an earthquake and tsunami blocked highways to the plant, the NRC said.
Mattson said the added safety measures likely to result from a more demanding look at nuclear plant vulnerabilities should not impose unreasonable costs on most plants. "I don't think it's breaking the bank," he said in an interview. "A higher sea wall [at the Fukushima Daiichi plant] wouldn't have broken the bank compared to what Japan will have to pay without the sea wall.
"Some of the older plants could be shut down, but some are beyond their design life. You shouldn't shut them down willy-nilly, like Germany did. But you ought to look at them really hard, with 'Fukushima eyes,' and see how comfortable you are."
Reprinted from Climatewire with permission from Environment & Energy Publishing, LLC. www.eenews.net, 202-628-6500