Spent nuclear fuel from the retired San Onofre nuclear plant will be stored underground in casks designed by New Jersey-based Holtec International, plant manager Southern California Edison announced Thursday.
The selection of a cask supplier allows Edison to move forward with transferring used fuel from cooling pools to so-called dry storage in thick stainless steel casks, which rest inside thick concrete bunkers.
Edison had narrowed its options to Holtec and a second U.S.-licensed supplier named Transnuclear, a subsidiary of Paris-based nuclear-energy giant Areva. The two storage systems shared many features, including the ability to be transported should the U.S. government and nuclear industry come up with a long-term solution for consolidating and safeguarding highly radioactive waste.
Holtec's storage system is buried just below ground. Canisters are lowered into a concrete monolith and topped with a 12-ton steel and concrete lid, Edison said.
A small portion of the used nuclear fuel produced over the 45-year operating lifetime of San Onofre already has been transferred to 51 canisters provided by Areva and will remain in above-ground concrete bunkers.
In switching to the Holtec system, "we concluded this underground design is best suited to safely and securely store used nuclear fuel at San Onofre until the federal government removes the fuel from site," said Chris Thomson, vice president of decommissioning for Edison, in a statement.
Removal could be several decades away, or more. Edison plants to dismantle the plant and store radioactive materials within 20 years, under a decommissioning plan submitted to the Nuclear Regulatory Commission.
A community engagement panel assembled by Edison to vet its decomissioning decisions with the public also looked at iron storage casks with thicker walls from a German vendor. That system raised concerns about the safety of lids that are bolted shut, rather than welded, and likely regulatory delays.
Panel Chairman David Victor, in a paper published this week, said that going with a U.S.-licensed vendor "assures us that we can learn from the real experience across the U.S. industry and that we have lots of partners in case issues arise with casks over time."