05000334/FIN-2011007-03
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Finding | |
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Title | Degraded Voltage Relay Time Delay |
Description | The team identified an Unresolved ltem (URl) regarding the adequacy of the BVPS degraded voltage protection scheme. The existing degraded voltage relay time delay of 90 +- 5 seconds does not appear to be consistent with the assumption in the UFSAR accident analysis for safety injection flow. The team found that Technical Specification Table 3.3.5-1, Loss of Power Diesel Generator Start and Bus Separation Instrumentation, ltems 3 and 4, lists the degraded voltage relay time delay setpoint as 90 +- 5 seconds. However, the team noted that NRC letter dated June 2, 1977, sent to holders of operating licenses requiring the installation of degraded voltage relays, to ensure safety-related loads had sufficient voltage to respond to an accident, stated in Position 8.1.c that, The allowable time delay, including margin, shall not exceed the maximum time delay that is assumed in the FSAR accident analysis. The NRC safety evaluation report (SER) dated March 3, 1982, concluded that the proposed maximum time delay of 95 seconds does not exceed this maximum time delay. However, the team found that UFSAR Table 14.3.2-8 shows a time delay of < 17 seconds for safety injection flow with offsite power, and < 27 seconds for a loss-of-offsite power/loss-of coolant accident (LOOP/LOCA). The team was concerned that if offsite source voltage was degraded below the level where it was capable of performing its accident mitigation function, but not so low as to actuate the fast acting loss of voltage relays, the time delay assumptions in the accident analysis would not be satisfied. FENOC entered the apparent inconsistency between the design accepted in the 1982 SER and the criteria stated in the 1977 letter into the corrective action program (CR 1 1-95145) for evaluation and resolution. The item was considered unresolved pending NRC review of FENOC actions to address the inconsistency. |
Site: | Beaver Valley |
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Report | IR 05000334/2011007 Section 1R21 |
Date counted | Jun 30, 2011 (2011Q2) |
Type: | URI: |
cornerstone | Mitigating Systems |
Identified by: | NRC identified |
Inspection Procedure: | IP 71111.21 |
Inspectors (proximate) | K Mangan G Skinner F Arner M Young J Ayala M Yeminy L Doerfleind Spindlerg Hunegs S Barber |
INPO aspect | |
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Finding - Beaver Valley - IR 05000334/2011007 | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
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Finding List (Beaver Valley) @ 2011Q2
Self-Identified List (Beaver Valley)
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