Safety violations at Diablo Canyon nuclear plant
May 31, 2011
On April 26, Nuclear Regulatory Commission staff did a safety inspection at the Diablo Canyon nuclear power plant, as part of NRC inspections of all U.S. reactors that were triggered by the Fukushima Daiichi nuclear plant disaster in Japan. [NewYorkTimes]
Even though the NRC’s inspection report did not flag PG&E for a serious violation of the rules, it did list more than a half-dozen issues that could jeopardize the plant if it were confronted with the kind of chain reaction of unexpected disasters that struck the Fukushima nuclear complex.
The NRC investigators reported:
• The 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.
• Some doors at the plant required to protect against flooding of major safety equipment would not self-latch as required. One latch was “degraded,” they said.
• The plant’s six emergency diesel generators were located in the same plant area, and thus vulnerable to a “common mode” failure.
• An earthquake could cause a structural failure in the building where the fire truck is stored, and debris could block crews from using the truck.
• PG&E 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. PG&E intended to rely on the California National Guard to deliver diesel fuel for emergency generators if roads were impassable, but had no memorandum of understanding in place for the deliveries.
• Four 20-foot extension cables, used to operate fans that cool portable generators, were missing from their storage location.
PG&E spokesman Paul Flake told the New York Times issues reported by the NRC had been identified by the company’s own review after Fukushima, and an inspection by the Institute for Nuclear Power Operations, the industry’s confidential safety monitor. “All of the issues identified in the [NRC] inspection report are being addressed. We continue to work with the NRC to introduce safety improvements” required to protect the plant, he said.