A shipment of two pressurizers was returned to the San Onofre Nuclear Power Plant (SONGS) earlier this summer because a leak occurred during transport to a disposal site.

The pressure vessels were en route to Clive, Utah. On July 1, during a stop at the San Bernardino rail depot, a worker noticed fluid leaking from one of the 100-ton pressure vessels and notified Southern California Edison (SCE), the owner and operator of the San Onofre Nuclear Power Plant.

SONGS has dispatched a team to the site to seal and repair the leak, said Ron Pontes, SCE’s general manager of environmental radiation protection.

“Radiological studies confirm that no material left the train car,” he said. “Nothing dripped onto the floor around the train car and we have returned all the material to (SONGS).”

There is no danger to the population, he said.

The 37-foot-tall, 10-foot-wide, 16,500-gallon pressure vessels were to be completely dried and sealed. They are used to control the pressure of the reactor coolant system.

Southern California Edison

SCE’s investigation found that the leaking pressure vessel contained 190 gallons of water.

“This incident should not have happened,” Pontes said. “We are very disappointed in the way this thing was packaged, the fact that there was water in it that remained in this pressure vessel when the contractor thought it was dry and empty. … We take this very, very seriously and want to understand what went wrong here and make sure we learn from this incident.”

An investigation report by the U.S. Nuclear Regulatory Commission into the August 9 incident identified two minor violations: failure to ensure the integrity of the shipment and failure to properly classify the shipment.

“The safety significance of the issues was assessed as low and because the violations were not repeated and not intentional, they are being treated as non-complaint violations,” the report said.

SCE is conducting its own investigation into the matter and in the meantime, any shipments suspected of containing liquid will be held “until we understand what went wrong with this shipment,” Pontes said.

Since San Onofre began dismantling four years ago, more than 1,000 shipments of low-level radioactive material have been sent for disposal. Pontes said everything sent to Clive was at the lowest level, “barely radioactive.”

SCE plans to announce its results at a virtual community meeting on September 5 from 2-5 p.m.