A self-revealing
NCV of very low safety significance (Green) of
Technical Specification (TS) 5.4, Procedures, was identified for a procedural error which resulted in the inadvertent isolation of the
high pressure coolant injection (
HPCI) system. Specifically, on April 4, 2017, an instrumentation and controls (
I&C) technician did not correctly perform procedure
ISP-175B1, Reactor and Containment Cooling Instrument Functional Test/Calibration, which caused the
HPCI system to isolate. Exelons immediate response to the event included stopping the surveillance test, and developing and implementing a plan to restore the
HPCI system to an operable status. The
HPCI system was subsequently restored to service approximately five hours after the inadvertent isolation. Additional corrective actions included increased observations of peer checks and validation of
I&C activities. This issue was entered into the
CAP as
IR 03993791. This performance defficiency is more than minor because it is associated with the Equipment Performance attribute of the
Mitigating Systems cornerstone and affected the cornerstone objective to ensure the availability of systems that respond to
initiating events to prevent undesirable consequences. Specifically, the failure to correctly implement procedure
ISP-175B1 caused an isolation of the
HPCI system and rendered it unavailable to respond to an initiating event. In accordance with
IMC 0609.04, Initial Characterization of Findings, and Exhibit 2 of
IMC 0609, Appendix A, The
Significance Determination Process for Findings At-Power, issued June 19, 2012, the inspectors determined that this finding required a detailed risk evaluation since the
HPCI isolation resulted in a loss of safety function. Using the Standardized Plant Assessment Risk Model (
SPAR), the Region I senior reactor analyst (
SRA) determined this finding was of low safety significance (Green). The inspectors determined that this finding had a cross-cutting aspect in the area of Human Performance, Avoid Complacency, because the
I&C technician did not correctly implement error reduction tools and verify that the direct current voltage source was installed on the correct trip unit prior to performing the surveillance procedure. [H.12]
