05000348/FIN-2009005-05
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Finding | |
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| Title | Load Sequencer Operability during EDG Surveillance Tests |
| Description | The NRC identified a Green NCV of 10 CFR 50, Appendix B, Criterion III, Design Control, for failure to translate EDG system design into surveillance test procedures rendering LOSP emergency load sequencers inoperable during performance of those tests. The licensee entered the issue into the CAP as CR 2008105195 and is taking corrective action to modify the EDG LOSP circuit to maintain the operability of the LOSP emergency load sequencers during the performance of EDG surveillance tests. The failure to translate system design into procedures and instructions for performing EDG surveillance tests that rendered the LOSP emergency load sequencers inoperable was a performance deficiency. This performance deficiency was more than minor because required surveillance test procedures did not alert operators to the fact that the performance of those tests rendered the LOSP load sequencers inoperable and tests were performed that exceeded the allowed outage time for an inoperable sequencer. SDP phase 1 screening determined that core decay heat removal was affected within the mitigating systems cornerstone when the performance deficiency represented loss of a train of a safety function for greater than its technical specification allowed outage time. A phase 3 SDP was required because the phase 2 worksheets do not provide sufficient detail. The phase 3 analysis was performed by a regional SRA. The phase 3 result was <1E-6 for core damage frequency (CDF) and did not involve steam generator tube rupture or intersystem loss of coolant accident (LOCA) sequences and therefore was not a significant large early release frequency (LERF) risk contributor. The dominant sequences involved an LOSP with a failure of the LOSP sequencer while an EDG was in surveillance paralleled with the grid, failure of the operator to load the EDG, combined with failure of the opposite train EDG. With no emergency or offsite power provided, no RCP seal makeup, RCP seal cooling or service water would be available and a seal LOCA would result in core damage. No recovery credit was assumed in the analysis although the EDG themselves and the switchgear to the safety equipment would not have been affected. Factors which reduced the risk included the low exposure time and the availability of other mitigating equipment. The EDGs themselves would not be affected by the performance deficiency only the automatic loading subsequent to an LOSP. The ESF sequencers were not affected by the performance deficiency. The SDP result was Green, a finding of very low safety significance. No cross-cutting aspect was identified because the finding was not indicative of current plant performance |
| Site: | Farley  |
|---|---|
| Report | IR 05000348/2009005 Section 4OA5 |
| Date counted | Dec 31, 2009 (2009Q4) |
| Type: | NCV: Green |
| cornerstone | Mitigating Systems |
| Identified by: | NRC identified |
| Inspection Procedure: | |
| Inspectors (proximate) | E Crowe S Shaeffer W Rogers G Macdonald B Caballero S Sandal |
| INPO aspect | |
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Finding - Farley - IR 05000348/2009005 | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
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Finding List (Farley) @ 2009Q4
Self-Identified List (Farley)
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