Fuel Transfer Operations Update

A cask loading supervisor provides oversight during the download of canister #62 on May 13.

The San Onofre Nuclear Generating Station team is in the process of safely moving the remaining spent nuclear fuel currently in wet storage (pools) to dry storage, in robust stainless steel canisters. When the campaign began in 2018, 73 canisters needed to be stored. As of last night, 11 remain. The project is expected to be completed this summer.

Continuous Improvement

A key to ensuring the campaign continues safely has been a team focus on open communications, dialogue and a questioning attitude, where potential issues are identified, evaluated, and addressed early.

We continue to look for opportunities to improve our fuel transfer operations while maintaining high safety standards. As an example, improvements in the canister drying process have trimmed about 5 hours from each loading evolution. New practices, such as additional camera use during tasks for enhanced visibility, result in improving the ability of the team to reduce risk and improve performance. Workers at all levels are showing strong engagement and ownership of fuel transfer operations.

Nuclear Safety Culture behaviors are an expectation for all SONGS personnel, including our contractors, and SCE consistently reinforces these expectations to help ensure that issues are identified, evaluated, and appropriate management actions are taken. Additionally, we continue to assess our performance weekly to strengthen our processes.

Recent Cask Handling Crane Lesson Learned

Earlier this month, the Unit 3 cask handling crane experienced a slack cable condition which occurred when an empty canister (no nuclear fuel) and its associated transfer cask were placed on the bottom of the cask loading area of the spent fuel pool. The cause of the slack condition was hoist movement after the cask had come to rest on the pool bottom. Crane movement was immediately stopped.

Following the incident, the special lifting device (lift yoke) connecting the crane hook to the transfer cask was disengaged from the transfer cask and the crane block and lift yoke were raised above the water surface for visual inspection. It was observed that the hoist wire rope had moved outside of the upper weighted limit actuation plate causing the plate to be bent slightly inward.

Actions were taken to ensure the crane and lifting device were fully-qualified for return-to-service, including repairs, inspections and a test of the crane. Then, an independent, third-party review was performed by a specialist in nuclear cranes and rigging. They concluded that the inspections and adjustments and repairs fully restored the operating capability of the Unit 3 cask handling crane. Only then was it returned to service. A new camera installed near the bottom of the cask loading area will provide a better visual for the crane operator and help prevent a reoccurrence.

The download of canister #62 is closely monitored to ensure proper alignment.

NRC Inspection Report

The Nuclear Regulatory Commission has continued its inspection activities of fuel transfer operations at SONGS. The NRC recently released its latest inspection report April 28 for unannounced inspections that took place in January, February and March. The report included no findings or violations.

The multiple unannounced inspections were timed to observe risk significant activities during fuel transfer. The NRC inspectors noted that corrective actions taken after the August 2018 canister misalignment incident remained effective. They also noted the constant monitoring of canister status during lowering is preventing possible misalignment issues.

The full report is available here.


When the pandemic hit, SCE paused fuel transfer operations for several days and evaluated our ability to continue work and keep our workers healthy. The SONGS team implemented a pandemic protocol and focused on educating workers on protective measures. We continue to reinforce COVID-19 prevention behaviors.

(Posted May 14, 2020)