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Scratches on nuclear storage canisters at San Onofre pose no problems, NRC says after its own analysis

by in News

The Nuclear Regulatory Commission didn’t take anyone else’s word for it, officials said, but ran its own analyses to answer the nettlesome questions: How deep are the scratches marring canisters of radioactive nuclear waste at San Onofre? And do those scratches pose safety concerns to the public?

  • With the San Onofre Nuclear Generating Station as a backdrop Huy Pham of San Juan Capistrano walks south along the beach at San Onofre State Beach. Mark Rightmire, ORANGE COUNTY REGISTER

  • This Google Earth image shows how close the expanded dry storage area for spent nuclear waste will be to the shoreline at San Onofre Nuclear Generating Station. (Image courtesy of Google Earth)

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  • Jeff Carey, of Southern California Edison, takes a radiation reading from one of the Holtec HI-STORM UMAX dry storage containers for spent fuel on site at the decommissioned San Onofre Nuclear Generating Station in San Clemente, CA on Monday, March 18, 2019. (Photo by Paul Bersebach, Orange County Register/SCNG)

  • The Holtec Hi-Storm Umax dry storage system for spent fuel at San Onofre Nuclear Generating Station. (Courtesy of Southern California Edison)

  • A caution sign sits on one of the Holtec HI-STORM UMAX dry storage containers for spent fuel on site at the decommissioned San Onofre Nuclear Generating Station in San Clemente, CA on Monday, March 18, 2019. (Photo by Paul Bersebach, Orange County Register/SCNG)

  • Jim Peattie, General Manager of Decommissioning Oversight with Southern California Edison talks about the cask transporter during a tour at the San Onofre Nuclear Generating Station in San Clemente, CA. The machine transports a canister filled with 37 spent nuclear fuel assemblies to the Holtec HI-STORM UMAX dry storage system on site. (Photo by Paul Bersebach, Orange County Register/SCNG)

  • The Holtec HI-STORM UMAX dry storage system, in foreground, on site at the decommissioned San Onofre Nuclear Generating Station in San Clemente, CA. Officials gave a media tour on Monday, March 18, 2019. (Photo by Paul Bersebach, Orange County Register/SCNG)

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The NRC had its own inspector at seven of the eight visual inspections of the canisters, when operator Southern California Edison sent robots and 3-D video cameras creeping down into vaults.

The NRC then did an independent statistical analysis of the data, concluding that the scratches are less than 10 percent of the canister wall’s thickness. That’s not deep enough to pose any risks, officials said at a webinar on Monday, June 3.

“We did not simply accept a report from Southern California Edison,” said Linda Howell, acting director of the NRC’s Division of Nuclear Materials Safety. “We used a staff member with a doctorate in statistics, and used data from the visual inspections to do our own assessment. Our conclusion was that Southern California Edison’s conclusion was conservative.”

The cyber-meeting explained in more detail the NRC’s decision in May to allow Edison to resume moving radioactive waste from wet fuel pools into safer, dry storage. That work came to a halt on Aug. 3, after a 50-ton canister filled with waste got stuck on a rim near the top of the 18-foot-deep vault where it was to be entombed. Workers didn’t realize that the slings supporting the canister’s massive weight had gone slack and it hung there, unsupported, for close to an hour, in danger of dropping.

In November, the NRC laid blame squarely at Edison’s feet, saying it “fell asleep at the switch” and that the near-drop resulted from inadequate training, oversight and supervision. It wouldn’t allow work to resume until it understood what, if any, risk scratches pose to the canisters’ integrity.

Over the past 10 months, Edison has examined and revamped its fuel transfer operations, spokesman John Dobken said in a statement. Along with Holtec International, its waste storage contractor, it has developed more than 70 “corrective actions” to enhance and strengthen the process.

Those include the use of novel technology, more experienced workers and more stringent procedures, better training and intrusive oversight. Cameras and alarms have been added to machinery so many eyes and ears can monitor loading in real time.

“Now that the NRC has said fuel transfers can safely resume, Holtec crews are being remobilized and retrained and SCE has several weeks’ worth of internal reviews to perform before we are ready to announce a date for again moving spent nuclear fuel from wet to dry storage,” said Doug Bauder, SCE vice president and chief nuclear officer, in a prepared statement.

Twenty-nine of 73 waste canisters have been loaded into the Holtec UMAX dry storage system, and Edison’s focus will be on getting the rest of them loaded “without further incident,” he said.

Edison aims to have the work done by early next year, but there’s no date set yet for when loading will resume.

Two more meetings on San Onofre will be held this week:

  • The volunteer San Onofre Community Engagement Panel will get an update on the fuel transfer situation from 5:30-8:30 p.m. Wednesday, June 5, at the QLN Conference Center, 1938 Avenida del Oro, Oceanside. It will be streamed live at songscommunity.com.
  • And at 11:30 a.m. Friday, June 7, the U.S. House Committee on Oversight and Reform’s Subcommittee on Environment will hold a field hearing at the Chet Holifield Federal Building, 24000 Avila Road, Laguna Niguel. It will examine nuclear waste management in America, from moribund Yucca Mountain to proposed temporary storage sites in Texas and New Mexico, and will examine the NRC’s role as a regulator as well. It will be chaired by Rep. Harley Rouda, D-Newport Beach and streamed live at youtube.com/user/OversightDems

The NRC said the safety report on the Holtec UMAX system will be changed to reflect that some scratching on canisters may occur. For more on the technical basis for Edison’s conclusions on the scratches, see its report here.