The following additional information was obtained from the licensee by phone and email:
Administrative IROFS WT-165 and WT-166 require independent operators to sample and verify the V-1170 uranium concentration is below an administrative limit prior to discharge to the V-1160 tank. These IROFS were correctly performed on May 18, 2022, for both the V-1170A and V-1170B tanks. In between the 18th and the 23rd, the warm caustic filter was water washed with the process solution sent to the V-1170 tanks.
At 0422 EDT on May 23, 2022, the contents of V-1170A and V-1170B tanks were pumped to the T-1160B tank without the tank uranium concentration being updated following the warm caustic filter wash.
At 0925 EDT on May 23, 2022, an evaluation into the reportability of the event was initiated when a Uranium Recovery and Recycling Services (URRS) team manager contacted Criticality Engineering to report the transfer without the test results required by procedure. After reviewing updated tank test results, performing calculations to determine risk, and discussing actions taken by the operators, IROFS WT-165 and WT-166 were considered failed and IROFS WT-171, WT-172, WT-175 and WT-176 were considered degraded.
Per CSE-15C-S1-G3, the remaining safety margin was 1.000E-2, which was below the required 1.000E-4.
The result is reportable per 10 CFR Part 70 Appendix A (b)(2), 'Loss or degradation of items relied on for safety that results in failure to meet the performance requirements of 10 CFR 70.61.'
Following the event, the contents of V-1170A and T-1160B were tested and historical tank level indication data was reviewed with results well within the
IROFS limits. There was no safety impact as a result of the failed
IROFS.