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Nuclear Regulatory Commission dings San Onofre for ‘low safety significance’ violation

A couple relaxes on the beach next to the San Onofre Nuclear Generating Station earlier this month.
A couple relaxes on the beach next to the San Onofre Nuclear Generating Station earlier this month.
(Hayne Palmour IV / San Diego Union-Tribune)
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The federal agency in charge of nuclear safety issued a low-level violation to the operators of the San Onofre Nuclear Generating Station for not following proper protocol in one area dealing with the plant’s efforts to transfer canisters of spent nuclear waste from wet storage pools to a newly constructed dry storage facility.

In the run-up to the transfers that began in January, the Nuclear Regulatory Commission conducted six months of inspections at the nuclear plant. The findings were sent to the plant’s operator, Southern California Edison, this week.

While inspectors concluded Edison had completed all necessary requirements, the NRC had an issue with physical changes made to a steel plate inside Unit 2 of the plant that has not produced electricity since January 2012.

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When a canister is lifted from a wet storage pool, a lid is welded to its top. In case an earthquake should hit while the lid is being welded shut, the canister containing the fuel is held steady by large straps made of Kevlar material while being restrained against a wall by a base plate.

But on the wall of Unit 2, an existing steel plate jutted out a few inches, interfering with the base plate. The solution? Notch a 16-inch by 2-inch section out of the support plate to make it fit. An engineer OK’d the decision and the modification worked.

The NRC said the decision did not affect safety but changes to the base plate required approval from more than only one engineer. Since the “violation was of low safety significance,” the NRC issued what is called a “non-cited violation,” the lowest of NRC rankings.

The 33-page report also brought up a largely bureaucratic question about the methodology SCE used when computing a hypothetical drop of a canister in a storage pool in the event of an earthquake.

“It’s important for the public to understand that there was no risk to public safety regarding both of these issues, which is also noted in the NRC’s report,” Tom Palmisano, Southern California Edison’s vice president of decommissioning and chief nuclear operator at the plant, said in a statement.

The news comes less than one week after the NRC announced it was coming to San Onofre to conduct a one-week “special investigation” into an incident at the plant where a canister got wedged while being lowered into a storage cavity earlier this month.

Workers did not realize the canister was stuck on a ledge, about 18 feet from the storage cavity’s floor, for at least 20 minutes.

A worker brought the incident to light and Palmisano said he should have mentioned it earlier to the SONGS Community Engagement Panel, which gives the public quarterly updates on the decommissioning of the plant.

With the Aug. 3 incident fresh, Edison officials notified the Community Engagement Panel about the 33-page NRC report on Wednesday.

“We really want to take every step we can to be out in front when it comes to sharing information and answering questions,” Palmisano said. “We definitely want to be as pro-active as we can, to make sure people have the information.”

In March Edison reported a problem in March during the transfer of spent fuel at the plant. Work was delayed 10 days after workers discovered a piece of shim — essentially, a pin 4 inches by a half-inch — came loose while a canister was being loaded.

Edison received assurance from Holtec International — the canister’s designer and manufacturer — and an independent engineering firm that the canister’s integrity was sound.

San Diego advocacy group Public Watchdogs has been a harsh critic of Edison and the group’s executive director, Charles Langley, said this week’s NRC report represents a pattern.

“We urgently need 24-hour monitoring by NRC safety inspectors,” Langley said in an email. “Edison has once again shown that it has a callous disregard for public engagement and safety. This latest incident shows that Edison cannot be trusted.”

Thus far, 29 canisters have been moved from wet storage to dry storage but Palmisano has suspended future transfers until the NRC completes its special inspection and he is confident safety practices and procedures associated with moving the fuel meet his satisfaction. The NRC’s special inspection begins in Sept. 10 and will run for one week.

Fourty-four more canisters are scheduled to be transferred. The tentative completion date is the middle of next year.

The nuclear plant is home to 3.55 million pounds of spent fuel, accumulated during its time as a major source of electricity for ratepayers in Southern California.

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rob.nikolewski@sduniontribune.com

(619) 293-1251 Twitter: @robnikolewski