A self-revealing Green
NCV of
10 CFR 50, Appendix B, Criterion XI, Test Control, was identified for the licensees failure to flow test the Nuclear
Service Water System (NSWS) A Train Standby Nuclear
Service Water Pond (SNSWP) unit common supply
header at maximum design flow. The licensee entered this issue into their corrective action program as
PIP M-09-2216 and has taken corrective actions to increase the minimum required flow velocity, frequency, and duration of the A Train SNSWP unit common supply
header test procedure. The finding was more than minor because it affected the cornerstone attributes of protection against external events and equipment performance and the
Mitigating Systems objective of ensuring the availability, reliability, and capability of systems that respond to
initiating events to prevent undesirable consequences. Specifically, inadequate flushing of the A Train SNSWP unit common supply
header led to ineffective flushes and the accumulation of corrosion products which challenged the design function of the NSWS system. This finding was evaluated using
IMC 0609, Attachment 4, Phase I - Initial Screening and Characterization of Findings, to determine the safety significance. Since the finding was related to a seismic initiating event, a Phase III was required to be performed by an NRC Senior Risk Analyst. The Phase III analysis calculated the risk increase to be less than
1E-7 for both conditional core damage probability and conditional large early release probability, resulting in a determination of very low risk significance (Green). This performance deficiency was associated with the cross-cutting aspect of complete, accurate and up-to-date design documentation and procedures
H.2(c) as described in the Resources component of the Human Performance cross-cutting area.
