A shipment of two pressurizers was returned to the San Onofre Nuclear Generating Station (SONGS) earlier this summer because of a leak during transport to a disposal site.
The pressurizers were on their way to Clive, Utah. On July 1, during a stop at the San Bernardino railyard, a worker noticed liquid leaking from one of the 100-ton pressurizers and notified Southern California Edison (SCE), the owner and operator of the San Onofre nuclear plant.
SONGS dispatched a team to the site to seal and clean up the leak, said Ron Pontes, general manager for environmental radiation protection at SCE.
"Radiological surveys confirm that none of the material left the rail car," he said. "Nothing dripped onto the ground around the rail car, and we brought all that material back to (SONGS)."
There was no danger to the public, he said.
The 37-foot-tall, 10-foot-wide pressurizers, which have a volume capacity of 16,500 gallons, were supposed to be completely dried and sealed. They're used to control the pressure of the reactor coolant system.
SCE's investigation found the leaking pressurizer contained 190 gallons of water in it.
"This incident should not have happened,” Pontes said. “We're very disappointed in the way this thing got packaged the fact that there was water inside, remaining inside this pressurizer, when the contractor thought that it was dry and empty. ... We're taking this very, very seriously, and we want to understand what went wrong here, made sure we learn from that event.”
On Aug. 9, a U.S. Nuclear Regulatory Commission investigation report of the incident found two minor violations — failure to ensure shipment was leakproof and failure to properly classify shipment.
"The safety significance of the issues was determined to be low, and because the violations were nonrepetitive and not willful, these violations are being treated as Non-Cited Violations," the report said.
SCE is conducting its own investigation into the matter, and in the meantime, all shipments suspected to contain liquid are on hold "until we understand what went wrong with this shipment," Pontes said.
Since San Onofre started dismantling four years ago, more than 1,000 low-level radioactive shipments have been sent for disposal. Pontes said everything sent to Clive is at the lowest level, "barely radioactive."
SCE plans to release its findings at a virtual community meeting from 2 to 5 p.m. on Sept. 5.
