The NRC inspectors identified a finding of very low safety significance (Green) and an associated
NCV of
10 CFR 50, Appendix B, Criterion V on December 21, 2010. While observing performance of QCOS 0250-01,
MSIV [Main Steam Isolation Valve]
Scram Sensor Channel Functional Test, inspectors identified that the licensees surveillance procedure unacceptably preconditioned the
reactor protection system (
RPS) B limit switches during testing of the
RPS A switches, in that, the A switch testing also moved the Bswitches. The licensee had not previously evaluated the pre-conditioning to determine potential impact to the test and subsequently validated the inspectors assessment that the test methodology did unacceptably precondition the B
RPS limit switches. The issue was documented in the corrective action program as
Issue Report 1155212. The procedure was revised and subsequent retesting on March 26 and 27, 2011, demonstrated that all
MSIV RPS limit switches were
operable. This issue was more than minor because, if left uncorrected, the performance deficiency would have the potential to
lead to a more significant safety concern in that preconditioning could mask a condition which would prevent an automatic actuation of
RPS on
MSIV closure. Inspectors performed the
SDP phase 1 screening using
IMC 0609, Attachment 4, Table 4a,
Mitigating Systems Cornerstone column, and answered all questions No. Therefore, this finding is Green, or very low safety significance. The issue was considered a legacy issue and no cross-cutting aspect was assigned
