Fuel Transfer Operations Update
The team at the San Onofre nuclear plant is moving spent nuclear fuel from wet storage (in pools) to dry storage in robust, stainless-steel canisters. The current campaign to load the remaining fuel on site into 73 canisters began in 2018 and is scheduled to be completed this summer.
To date, 54 canisters, each containing 37 fuel assemblies, have been moved into the Holtec UMAX dry fuel storage system. Crews are moving one canister per week into dry storage and that pace is expected to continue throughout the rest of fuel transfer operations.
“We are seeing good development in terms of being a learning organization. Issues that are identified are addressed through the process and because of that we are making steady progress,” said Vince Bilovsky, SCE deputy decommissioning officer.
What We've Seen
Some of the changes incorporated into fuel transfer operations include leveling and alignment enhancements that the vertical cask transporter operator can utilize during downloading of canisters. In part because of this addition to the process, underload signals have been reduced. An underload signal alerts the operator that the canister isn't lowering smoothly and adjustments need to be made. Canisters 50 through 53 experienced no underload signals. Canister 49 experienced an underload signal as it approached the bottom of its storage vault. No unacceptable contact was identified following an analysis. The bottom of the canister, which is three-inch thick stainless steel, came to rest momentarily on a lower seismic support before settling into position. An inspector from the Nuclear Regulatory Commission was onsite during the download.
What We’ve Also Seen
In January, high winds near the site caused a branch to interfere with a power line resulting in a 45-minute loss of off-site power. Back-up power systems worked as expected. One canister of spent fuel was in the drying process and was placed in a safe condition until power could be restored.
Last month, during the drying process on another canister, a blower failed. The spent fuel canisters undergo vacuum drying using forced helium after being removed from the spent fuel pool. During the drying, there was a small ignition of some surface material inside the blower. Crews on site responded properly and corrective actions were put in place to prevent a reoccurrence.
During the COVID-19 pandemic, our team is taking necessary precautions based on CDC guidelines to reduce potential exposure. The safety and well-being of our workers and communities remain our top priority, and we are taking actions focused on maintaining the normal level of operations at the San Onofre nuclear plant.
Fuel transfer operations, as well as decommissioning work, are continuing but with new protocols in response to COVID-19.
“We’re monitoring the situation very closely, on a day-to-day basis, with plans in place to ensure the appropriate levels of safety and security at the site,” Bilovsky said.
Employees who can telecommute are being encouraged to do so, and to utilize tools such as social distancing while at the site. Whether in the field or the office, safety is our focus at SONGS.
(Posted March 19, 2020)