San Onofre Team Honored With Innovation Award for Spent Nuclear Fuel Canister Repair Method

ROSEMEAD, Calif., June 7, 2021 — The Nuclear Energy Institute (NEI) honored engineers at the San Onofre Nuclear Generating Station for their work enhancing spent nuclear fuel storage safety. Southern California Edison Engineering manager Jerry Stephenson and project manager Allen Williams, along with their industry partners, received the Top Innovative Practice (TIP) Award during NEI’s 2021 Nuclear Energy Assembly.

Stephenson and Williams helped develop a robotic repair method for spent fuel storage canisters that would let the canisters be repaired in place using a process called metallic overlay. This process uses a specially designed nozzle to accelerate, to supersonic speeds, small particles of the metal to be applied, in this case nickel. The velocity results in a metallurgical bonding with the base metal of the canister surface on impact, mitigating any degradation, such as a microscopic crack.

Jerry Stephenson and Allen Williams
Jerry Stephenson and Allen Williams were honored with a Top Innovative Practice award from the Nuclear Energy Institute.

For stainless steel canisters used in spent fuel storage, the most likely challenge to canister integrity is chloride-induced stress corrosion cracking. It produces a short, tight crack and would require a small repair area. Because a loaded canister has a high surface radiation dose rate, removal of the canister from its storage location is not desirable. Performing the repair robotically, in place, is clearly the best alternative.

“The team worked really well together to make this repair method happen,” said Stephenson. “We were able to develop, test, fabricate, field test and qualify the process in a matter of months. The process was demonstrated successfully in both the laboratory and in the field at the SONGS site.”

11-13-2019k ISFSI Aging Mngmnt Test Canister and Heater Bank_MP17466
The test canister is installed at SONGS in 2019. The electrically heated canister simulates a spent fuel canister, but without containing nuclear material.

With no repair method commercially available, SCE took the initiative to develop this technique in response to a 2015 California Coastal Commission requirement to develop an Inspection and Maintenance Program. The commission approved the program last July after review by an independent engineering firm chosen by the commission. The process developed by SCE was based on initial research performed by the Electric Power Research Institute (EPRI).

The field test was performed in December 2019, using an electrically heated test canister installed at the San Onofre UMAX dry fuel storage system, which simulates a stored canister but with no nuclear fuel inside. Representatives from the Nuclear Regulatory Commission, EPRI and the industry were present to observe.

Fellow recipients of the award include RTT Robotics LLC, which developed the robotics to deploy the repair technology, and VRC Metal Systems, developer of the metallic overlay repair method.

NEI’s annual Top Innovative Practice Awards recognize those employees whose new ideas and approaches have a direct impact on improving the safety and reliability of nuclear energy.

Watch the video below for more information on the repair program.

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Media Contact: John Dobken, (626) 302-2255

About Southern California Edison

An Edison International (NYSE: EIX) company, Southern California Edison is one of the nation’s largest electric utilities, serving a population of approximately 15 million via 5 million customer accounts in a 50,000-square-mile service area within Central, Coastal and Southern California.