There was an incident in August at the San Onofre Nuclear Generating Station in which a canister filled with spent nuclear fuel got wedged into a storage cavity about 18 feet above the floor.
While the incident did not pose a threat to the public or workers at the plant, which is undergoing the decommissioning process, it did raise a level of concern.
Southern California Edison is now transferring 73 canisters of nuclear waste from “wet storage” to a newly constructed “dry storage” facility at San Onofre.
The Aug. 3 incident with the wedged canister is the second in five months related to fuel transfer at the plant — and that concerns David Lochbaum of the Union of Concerned Scientists.
“A lot of other canisters have been moved without such incidents,” said Lochbaum, director of UCS’s Nuclear Safety Project in a San Diego Union-Tribune report. “So while neither one of these (incidents) caused harm, you need to quit tempting fate and have skill be more part of the equation than luck.”
A nuclear engineer, Lochbaum worked in the nuclear power industry for 17 years and spent one year at the Nuclear Regulatory Commission, the federal agency in charge of protecting public health and safety related to nuclear energy.
Back in March, the fuel transfer was delayed 10 days after workers discovered a piece of shim — a pin 4 inches by a half-inch — came loose while a canister, designed by New Jersey-based Holtec International, was loaded at San Onofre. Edison received assurance from Holtec and an independent engineering firm the canister’s integrity was sound. Fully loaded, a canister weighs about 45 tons.
Tom Palmisano, vice president of decommissioning and chief nuclear operator at the plant, called the Aug. 3 incident “unacceptable” and has suspended all transfers of spent fuel until “the handling practices, the human-performing practices, the procedures are sufficient and are demonstrated to my satisfaction.”
After studying the Aug. 3 incident, Lochbaum concluded it was unlikely the wedged canister of irradiated fuel could have dropped 18 feet.
The incident came to light after a man identifying himself as an industrial safety worker at the plant stood up during the public comment period at the quarterly Community Engagement Panel meeting earlier this month and described what happened Aug. 3.
David Fritch said a canister being lowered into what is called a “cavity enclosure container” got stuck but two workers guiding the descent did not realize it.
“So what we have is a canister that could have fallen 18 feet,” Fritch said in the published report. “It’s a bad day. That happened and you haven’t heard about it and that’s not right.”
Fritch said he’s been working on the site for about three months and said some workers are “under-trained,” some supervisors don’t thoroughly understand the transfer process and “we don’t have the proper personnel to get things done safely.”
The Union-Tribune left multiple voicemails with Fritch but has not received a return call.
Palmisano said Fritch is an inspector for a subcontractor who works for Holtec. Palmisano said “it’s not for me to disclose” the name of the company Fritch works for but said he had spoken to the president of Fritch’s company and the president of Holtec “and told them both that I commend Mr. Fritch for voicing his concerns.”
Palmisano said “there is a very snug fit” as the canisters are lowered into the cavity enclosure containers and it’s not unusual for the loading team to make “a few adjustments” to get the canister in place properly.
The enclosure containers are about 20 feet high and the canister got lodged on an inner ring that helps guide it into place.
But the Holtec crew were unaware the canister was wedged. About 20 minutes later, an oversight team recognized the mistake and the canister was re-adjusted and successfully lowered to the bottom. Once inserted, the canisters rest largely underground in the cavity enclosures at the dry storage facility.
The incident happened on a Friday and Palmisano said the following Monday Edison’s staff at the plant notified the NRC, and Palmisano decided to suspend subsequent transfers.
“It’s an unacceptable incident,” Palmisano told the Union-Tribune but said the “very robust design” of the canister would have prevented any radiological leak — even if it had fallen 18 feet.
Lochbaum agreed, saying safety analyses of the canister showed it “would have remained intact so that there would not have been a release of radioactivity to harm workers or the public.”