NRC requests earthquake risk analyses from two western U.S. reactors

The Nuclear Regulatory Commission (NRC) requires more earthquake risk analyses from two western U.S. nuclear power plants, located in Benton County, Washington, and Avila Beach, California.

These plants are two of the three operating in the western U.S., and they will be required to conduct in-depth analyses to update their level of earthquake risk. The NRC has set the plants’ deadline as June 30, 2017.

NRC staff will continue to inspect the Palo Verde nuclear power plant in Wintersburg, Arizona, to determine if the plant requires additional risk analysis by December 31, 2020.

These requirements are in light of reviewing updated earthquake hazard information. Seismic activity suggests that all three of the plants' methods for engineering and construction need additional safety margins beyond the original margins.

“This information shows us how the plants’ new earthquake hazard compares to the ground movement considered in the plants’ original designs,” Bill Dean, director of the NRC’s Office of Nuclear Reactor Regulation, said. “The evidence we’ve seen so far leaves us confident the plants are safe to continue operating while they do more analysis. If a plant’s new hazard exceeds the original design, that additional analysis will determine if there are any changes in accident risk from an earthquake. Plants must also do shorter-term work to see if they should enhance key safety equipment while the more substantial analysis is being done.”