Title
10 CFR Part 50, Appendix B, Criterion V, Instructions, Procedures, and Drawings, requires, in part, that activities affecting quality shall be prescribed by documented procedures of a type appropriate to the circumstances and shall be accomplished in accordance with these procedures. Contrary to the above, on October 17, 2017, with Unit 2 in Mode 5, Cold Shutdown, the licensee failed to accomplish procedure 2C12.2, Purification and Chemical Addition Unit 2; Revision 34. Specifically, control room operators signed off steps as completed without validating that the procedure actions were performed in the field. These procedure steps that intended to close letdown valves and open purification valves, resulted in unintended transfer of primary coolant from the
RCS to the chemical and volume control system hold-up tank instead of back to the
RCS. In turn, this resulted in a reduction in
RCS inventorywith reactor vessel level at approximately 1 foot below the
flange (reduced inventory operations). Due to operators quickly recognizing a lack of letdown flow as discussed during a pre-job brief, the purification evolution was halted and actions were taken to restore reactor vessel level.Because the inspectors answered No to questions B.2 and B.3 under Exhibit 2,
Initiating Events Screening Questions of
IMC 0609, Appendix G, Attachment 1, Shutdown Operations
Significance Determination Process Phase 1 Initial Screening and Characterization of Findings, the finding screened as very low safety significance (Green). Specifically, the loss of inventory event was self-limiting such that the leakage would have stopped before impacting the operating method of
decay heat removal (
shutdown cooling via
RHR in this case). The issue was entered into the licensees
CAP as
CAP 501000003923. Corrective actions included an operations department human performance clock reset to share the lessons learned from the event.
