SONGS Fuel Transfer Operations Update
Since posting our previous update, the team has safely placed two more canisters of spent nuclear fuel in the Holtec dry storage system. Canisters 32 and 33 were the third and fourth to be stored since fuel transfer operations (FTO) re-started on July 15. A total of 73 canisters will be stored in what’s known as the expanded independent spent fuel storage installation (ISFSI).
We continue to see healthy interaction between the work groups and the oversight team with plenty of respectful feedback and coaching, and a continuing low threshold for identifying issues and areas for improvement. This was one of the core improvements we focused on during the comprehensive review of FTO.
The load monitoring system installed after the Aug. 3, 2018, event continues to perform as expected. This is a first of a kind system and part of an industry leading implementation of improved safety design features. The load monitoring system allows the operator lowering the canister to be aware of even a small reduction in the load on the slings as the canister is placed. If any reduced load is sensed, the operator stops and ensures all is well and no hang-up occurs.
One delay we experienced involved a weld on the canister closure ring. This is one of the last steps in sealing the canister before moving it out of the fuel handling building and to the dry storage pad. An interference in the weld path caused an approximate one inch nudge of the welding arm resulting in some damage to the ring. Work stopped as the condition was evaluated by the welding vendor, SCE engineers, and our third party welding experts. A conservative procedure was approved to resolve the issue and a re-work activity (a code-compliant base metal repair) was performed to bring the component back into conformance with the licensed design.
This past weekend, we loaded the 37 fuel assemblies into canister 34 in Unit 3 and are preparing to weld it closed.
Another activity that happened this past week involved the replacement of the demineralizer in the Unit 3 fuel handling building. This is the piece of equipment that keeps the spent fuel pool water crystal clear. The demineralizer, a 3000-pound tank that holds small resin filtering beads, pulls in water from the pool which then flows through the filtering beads where impurities are captured. The clean water then exits the bottom of the tank and back into the pool.
Throughout our activities, we have been in communication with inspectors from the Nuclear Regulatory Commission.
We will continue to provide updates as we move through fuel transfer operations at San Onofre.