The licensee identified a finding of very low safety significance (Green) and associated
NCV of License Condition 2.C.4 through a planned surveillance test for the failure to implement and maintain in effect all provisions of their approved
fire protection program. Specifically, the installation of the intake structure pre-action sprinkler system did not comply with
NFPA 13 (1983) section 3-11.1.1, which requires that all sprinkler pipe and fittings shall be so installed that the system may be drained and resulted in the plugging of the sprinkler system. This prevented water from flowing through sprinkler heads and caused the system to be non-functional. The performance deficiency was determined to be more than minor because it was associated with the
Mitigating Systems cornerstone attribute of Protection Against External Factors (Fire) and affected the cornerstone objective of ensuring the availability, reliability, and capability of systems that respond to
initiating events to prevent undesirable consequences (i.e., core damage). The Region III Senior Risk Analyst (
SRA) used the risk assessment tools of
IMC 0609, Appendix F, Fire Protection
SDP, and performed bounding analyses using the Monticello Standard Plant Analysis Risk (
SPAR Model), Version 8.15. The
SRA also reviewed and discussed the licensees bounding risk assessment documented in
PRA Memo 11-01-, Revisions 0 and 1, Risk Assessment of Intake Fire Suppression System Plugging. The finding was determined to be of very low safety significance (green) because the risk increase using bounding assumptions was below
1E-6. The licensee entered this issue into their corrective action program as
AR 01305183, Intake Fire Sprinkler Configuration Discrepancy, and restored the functionality of the sprinkler system by flushing the piping and replacing system components. The licensee further planned to modify the system to allow proper drainage in accordance with the design requirements.
