10 CFR 50 Appendix B, Criterion XVI, Corrective Action, requires in part that
conditions adverse to quality are promptly identified and corrected. Contrary to the above, the licensee identified steam leaks in the vicinity of the C
SG steam supply valve (Q1N12HV3235B) to the Unit 1
TDAFW pump as early as November 17, 2007 and did not take prompt corrective actions to repair the leaks. As a result of the failure to implement corrective actions to repair the steam leaks, the o-ring for the air
accumulator associated with Q1N12HV3235B was subjected to a high temperature environment and degraded to the point that the valve was declared
inoperable when it failed to meet surveillance test acceptance criteria on March 27, 2009. This issue was identified in the licensees
CAP as CR 2009103283. Following the failure of Q1N12HV3235B on March 27, 2009, the licensee completed repairs to the previously identified steam leaks and the failed actuator o-ring. Q1N12HV3235B was retested satisfactorily and returned to service on April 30, 2009. This finding was assessed using
IMC 0609,
SDP, Phase 1 screening worksheet for the
mitigating systems cornerstone column and determined to require a Phase 2 analysis because the finding represented the loss of safety function of a single steam supply to the
TDAFW pump for greater than the allowed TS outage time of seven days as given by condition A of
TS 3.7.5,
AFW System. A Regional Senior Reactor Analyst performed a Phase 3 evaluation under the
Significance Determination Process and determined that the finding was of very low safety significance (Green). The exposure time for the analysis was 268 days. The analysis assumed the Turbine Driven
Auxiliary Feedwater Pump failed but, could be easily recovered. The dominant accident sequence was a dual unit Loss of Offsite Power with loss of the
Emergency Diesel Generators. The Turbine Driven
Auxiliary Feedwater Pump would continue to operate but, due to the performance deficiency and an independent failure of the other steam supply to the turbine portion of the pump, it failed. Neither offsite power nor an
Emergency Diesel Generator was recovered in two
2 hours2.314815e-5 days <br />5.555556e-4 hours <br />3.306878e-6 weeks <br />7.61e-7 months <br /> which led to core damage
