The Nuclear Regulatory Commission (NRC) has set a June 2017 deadline for two of three nuclear power stations in the West to do in-depth analyses of their updated earthquake risk.
The NRC is requiring the Columbia plant in Benton County, Wash., and the Diablo Canyon plant in Avila Beach, Calif., to submit their detailed risk analysis by June 30, 2017.
Operated by Energy Northwest, Columbia is a single-unit boiling water reactor (BWR) with a generating capacity of roughly 1,000 MW. Diablo Canyon is a dual-unit pressurized water reactor operated by PG&E (NYSE:PCG) with a combined generating capacity of about 2,200 MW.
The NRC continues to examine information from Palo Verde in Wintersburg, Ariz. Palo Verde consists of three PWRs operated by the utility subsidiary of Pinnacle Capital West (NYSE:PNW). Each Palo Verde unit has a generating capacity of more than 1,300 MW.
If NRC concludes the plant needs the in-depth risk analysis it must complete the work by Dec. 31, 2020. The agency established these due dates after reviewing updated earthquake hazard information from the plants.
The seismic submittals showed all three Western plants’ engineering and construction methods added safety margin beyond their original designs’ anticipated hazards. Should the plants’ additional analysis indicate more permanent actions are necessary, the NRC will ensure the plants respond appropriately.
“This information shows us how the plants’ new earthquake hazard compares to the ground movement considered in the plants’ original designs,” said Bill Dean, director of the NRC’s Office of Nuclear Reactor Regulation. “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.”
The sites submitted the earthquake hazard information in March as part of the NRC’s response to the 2011 Fukushima nuclear accident.
All three plants are already working to comply with the NRC’s March 2012 Orders for additional safety equipment. Such equipment ranges from installed battery banks and pumps to portable backup pumps, hoses and diesel generators as well as supplies that can be flown in from off-site and regional response centers.
The plants must also employ enhanced spent fuel pool monitoring. For example in early 2012 NRC required all domestic plants to install water level instrumentation in their spent fuel pools.
Columbia is working to comply with a third March 2012 Order, updated in 2013, requiring hardened venting systems to safely relieve pressure if an accident occurs.