A self-revealed
NCV of very low safety significance (Green) of Title 10 of the Code of Federal Regulations (10 CFR) Part 50, Appendix B, Criterion V, Instructions, Procedures, and Drawings, was identified wherein, on October 13, 2017, Dominion failed to accomplish an activity affecting quality, Plant Cooldown, in accordance with approved procedures. Specifically, during solid plant cooldown, over the course of 18 seconds,
reactor coolant system (
RCS) pressure increased from 350 psia to 472 psia, which exceeded the limit of 435 psia established by Attachment 1,
RCS Cooldown Curves, of operating procedure OP 3208, Plant Cooldown, Revision 028. Dominion operations staff took prompt actions to restore
RCS pressure within limits and completed a required engineering evaluation to determine the effect of the out of limit condition on the structural integrity of the
RCS. Dominion entered this issue into the corrective action program (
CAP) as condition report (CR) 1080842 and completed a root cause evaluation of the event. This finding was determined to be more than minor because it adversely affected the configuration control attribute of the
Barrier Integrity cornerstone objective to provide reasonable assurance that physical design barriers (
RCS) protect the public from radionuclide releases caused by accidents or events. The inspectors evaluated the finding using
IMC 0609, Appendix G, Attachment 1, Shutdown Operations
Significance Determination Process Phase 1 Initial Screening and Characterization of Findings, and determined the finding to be of very low safety significance (Green). The finding had a cross-cutting aspect in the area of Human Performance related to Work Management because the licensee did not implement an adequate process of planning, controlling, and executing work activities such that nuclear safety was the overriding priority. Specifically, Dominion failed to recognize the increased risk of isolating instrument air during solid plant operations. [H.5]