By John Stang
Management at the San Onofre Nuclear Generating Station (SONGS) in California is investigating the spill before dawn Wednesday of 7,000 gallons of nonradioactive sewage into the Pacific Ocean.
Officials with plant majority owner Southern California Edison (SCE) discussed the spill Thursday evening with the SONGS Community Engagement Panel during a Skyped meeting.
An unexpected “slug of water” hit SONGS’ sewage treatment plant, pushing sewage and water through a pipeline extending 6,300 feet offshore, said Ron Pontes, manager of decommissioning environmental strategy for SONGS. Investigators did not know Thursday evening where the extra water came from or what caused it to flood into and out of the plant.
“We’re in the beginning stages of it,” said Doug Bauder, vice president of decommissioning and chief nuclear officer at SONGS. The sewage plant is out of service until the investigation is complete.
The Nuclear Regulatory Commission and the San Diego County government have been notified of the incident.
The oceanside nuclear plant has been closed since 2013, with the permanent retirement of its last two operational reactors after faulty steam generators were installed in each. Major work under the $4.4 billion decommissioning began in February and is scheduled to continue into 2028, though some deconstruction activities are being reduced in response to the COVID-19 outbreak.
Transfer of spent fuel from reactor Units 2 and 3 continues, and is scheduled to wrap up this summer. At that point, SONGS’ storage pad will hold about 3.5 million pounds of used fuel rods from its three reactors. Unit 1 was shuttered in 1992 and subsequently mostly decommissioned.
At Thursday’s meeting, SONGS officials briefed the panel and public on three other incidents, which they said slowed the spent-fuel offload but did not affect the completion schedule. As of Thursday, contractor Holtec International had moved 55 of 73 canisters to dry storage. The site is averaging putting one canister into dry storage per week.
On Jan. 29, high winds caused a 45-minute power outage while wet fuel was being dried. Safety measures were immediately implemented. The incident showed a need to improve some emergency lighting, Bauder said.
When the 49th canister was inserted into its vertical dry storage slot, tiny guidance prongs on the outer bottom of the cask did not neatly fit into the proper spots in the bottom of the vertical slot. The canister had to be adjusted to a proper fit. That was accomplished in the proper way, Bauder said.
When the 51st canister was being dried prior to movement, a piece of loose plastic caught fire and created a flame similar in size to one produced by a cigarette lighter. It was quickly put out, Bauder said.
