Report: NRC not holding Diablo Canyon nuclear plant to earthquake safety standards

The Nuclear Regulatory Commission (NRC) is not holding the Diablo Canyon nuclear plant in California to the same standards it requires of every other nuclear facility to address potential earthquake hazards, according to a report by the Union of Concerned Scientists. UCS prepared the report, “Seismic Shift: Diablo Canyon Literally and Figuratively on Shaky Ground,” for the Alliance for Nuclear Responsibility.

“This is a dangerous double standard,” said David Lochbaum, director of UCS’s Nuclear Safety Project and author of the report. “At other facilities, the NRC enforced its safety regulations and protected Americans from earthquake threats. Today, in the case of Diablo Canyon, the NRC is ignoring its regulations, unfairly exposing millions of Americans to undue risk.”

Diablo Canyon sits near earthquake fault lines. In late 2008, the plant’s owner, Pacific Gas & Electric (PG&E), informed the NRC about a previously unknown earthquake fault line running as close as 2,000 feet from Diablo Canyon’s two reactors that could cause more ground motion during an earthquake than the plant was designed to withstand. Since this new fault was discovered, the NRC has not demonstrated that the reactors meet agency safety regulations, according to the report.

When similar concerns surfaced at nuclear facilities in California, Maine, New York, Pennsylvania and Virginia, the NRC did not allow the plants to continue to operate until the agency determined they met safety regulations.

In particular, the NRC needed to be sure that a number of devices, including “shock absorbers” on piping and other components, would limit earthquake damage. In contrast, the NRC has allowed PG&E to continue to operate Diablo Canyon’s reactors despite this known threat, according to the report.

For example, in March 1979, the NRC ordered Beaver Valley Unit 1 in Pennsylvania, FitzPatrick in New York, Maine Yankee, and Surry Units 1 and 2 in Virginia to shut down after it discovered an error in the computer code that analyzed earthquakes and associated protective features of these plants.

The agency did not allow the five reactors to resume operating until plant owners reevaluated earthquake hazards, input proper computer codes, and installed or upgraded protection devices to better protect the plants from earthquakes. The burden of proof was on each of these facilities to demonstrate compliance with federal safety regulations.

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