Diablo Canyon and Earthquake Risk (2013)

November 2013
The NRC isn't enforcing seismic regulations at the Diablo Canyon Nuclear Power Plant.

California's Diablo Canyon Nuclear Power Plant sits near several earthquake fault lines. One of these—discovered in late 2008—is a mere 2,000 feet from Diablo Canyon's two reactors, and could cause more ground motion during an earthquake than the reactors were designed to withstand.

Despite enforcing seismic regulations in similar situations elsewhere, the Nuclear Regulatory Commission (NRC) hasn't enforced them at Diablo Canyon—exposing Americans to undue risk.

Earthquake risk at Diablo Canyon

The risk of an earthquake at Diablo Canyon is due to the site's location near a number of fault lines, both offshore and inland from the plant. In fact, dozens of earthquakes have already occurred at or near Diablo Canyon.

Past earthquakes do not mean that Diablo Canyon will experience an equal number of earthquakes in the future. They also do not mean that Diablo Canyon will avoid larger or closer earthquakes.

They mean that Diablo Canyon's seismic risks should be very carefully evaluated and acted upon—neither of which has happened.

Regulatory inaction from the NRC

The NRC has not used the methods and assumptions legally required to determine if the Diablo Canyon reactors can withstand large eathquakes. If such an earthquake occurs, it may result in dire consequences for tens of thousands of Californians.

This failure of the NRC was brought to light in 2008, when a new fault line was discovered 2,000 feet from the reactors—and only 985 feet from the plant's intake structure. Questions about the plant's ability to withstand earthquakes have been around since the reactors began operating in the 1980s.

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

Yet, the Diablo Canyon Nuclear Power Plant continutes to operate. As it has at other plants with similar issues, the NRC should enforce its seismic regulations at Diablo Canyon. The potential consequences of inaction are severe.

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