Green . The inspectors reviewed a self -revealing, non- cited violation of
10 CFR 50, Appendix B, Criterion V, Instructions, Procedures, and Drawings, because
PG&E personnel failed to follow the requirements of AD7.ID14, Assessment of Integrated Risk, Revision 11. Specifically,
PG&E personnel failed to obtain shift manager permission, conduct a protected equipment briefing, and document shift manager approval prior to performing work on protected equipment. This resulted in a loss of flow of cooling water to one of two in- service
shutdown cooling residual heat removal heat exchangers and subsequent perturbation in
reactor coolant system temperature during refueling outage 1R20. The inspectors determined that
PG&E s failure to follow AD7.ID14, Assessment of Integrated Risk, Section 5.14 Performing Work on Posted Protected Equipment, was a performance deficiency within
PG&Es ability to foresee and correct. This performance deficiency was considered to be more than minor because it impacted the configuration control attribute of the
Mitigating Systems cornerstone and its objective to ensure the availability, reliability, and capability of systems that respond to
initiating events to prevent undesirable consequences. Specifically, the loss of cooling flow to the
RHR heat exchanger while in
shutdown cooling mode resulted in a perturbation in
RCS temperature of approximately 8 degrees Fahrenheit. The finding was evaluated in accordance with
IMC 0609, Appendix G, Shutdown Operations
Significance Determination Process, and determined to be of very low safety significance (Green) since it did not represent a loss of system safety function of at least a single train for greater than four hours. The finding had a cross- cutting aspect in the area of human performance associated with conservative bias because
PG&E personnel did not use decision- making practices that emphasize prudent choices over those that are simply allowable. Specifically, despite being authorized to close component cooling water cross connect valves by the work control process,
PG&E personnel did not question the impact of their actions on
shutdown cooling [H.14 ].
