05000483/FIN-2014008-03
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Finding | |
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| Title | Emergency Diesel Generator Operability Evaluations using 7 Day Mission Time |
| Description | The team identified an unresolved item concerning the licensees operability evaluations associated with a 7-day mission time for the emergency diesel generators as written in Station Procedure APA-ZZ-00500 Appendix 1, Operability and Functionality Determinations, Revision 22, and the assumption in FSAR Section 3.1.2 crediting the loss of offsite power and restored in 7 days. The team noted that the design basis accidents in FSAR Chapter 15 were analyzed to 30 days and questioned whether operability determinations using an emergency diesel generator 7-day mission time was appropriate. The team reviewed CARs 201303303 and 201303613 and Station Procedure APA-ZZ-00500 Appendix 1, Operability and Functionality Determinations, Revision 22, concerning jacket water leaks on emergency diesel generators A and B. The team noted the station had used a 7-day mission time for the emergency diesel generators operability evaluations and declared both emergency diesel generators operable. Station Procedure APA-ZZ-00500 Appendix 1 stated in part that the emergency diesel generator mission time is 7 days [and that] this is consistent with the 7-day capacity of the emergency diesel generator fuel storage tanks. The team noted that Technical Specification Basis 3.8.3, Diesel Fuel, Lube Oil, and Starting Air and FSAR Section 9.5.4, Emergency Diesel Engine Fuel Oil Storage and Transfer System do require a 7-day capacity for the emergency diesel generator fuel storage tanks. This requirement, in conjunction with the ability to obtain replacement of fuel supplies within 7 days, supports the availability of the emergency diesel generators required to shut down the reactor and to maintain it in a safe condition for an anticipated operational occurrence or a postulated design basis accident with a loss of offsite power. The licensee stated the basis for the emergency diesel generator 7-day mission was contained in FSAR Section 3.1.2 Additional Single Failure Assumptions, and was part of the original FSAR submittal to the NRC, and not APA-ZZ-00500 Appendix 1. FSAR Section 3.1.2 states, in part, In designing for and analyzing for Design Basis Accidents (i.e., large break loss-ofcoolant accident, main steam line break, main feedwater line break, rod rejection, locked reactor coolant pump rotor or shaft break, fuel handling accident, or steam generator tube rupture), the following assumptions (a-f) are made in addition to postulating the initiating event. e. All offsite power is simultaneously lost and is restored within 7 days (except for the events postulated to occur during MODE 5, MODE 6, and/or during movement of irradiated fuel assemblies when the plant is MODE 5 or MODE 6 or with the core fully offloaded, such as a fuel handling accident, a loss of all offsite power is not required to be assumed in addition to a single failure.) The team reviewed Safety Evaluation Report (SER) and FSAR Section 15.0 Accident Analysis to determine if the stations basis of restoring offsite power in 7 days was appropriate when evaluating operability of emergency diesel generators for degraded nonconforming conditions. The SER did not document whether the NRC approved or disapproved the assumption of restoration of offsite power in 7 days during a design basis accident (FSAR Section 15). However, the team noted the following contained in FSAR Section 15: The basic principle applied in relating design requirements to each of the conditions is that the most probable occurrences should yield the least radiological risk to the public, and those extreme situations having the potential for the greatest risk to the public shall be those least likely to occur. Where applicable, reactor trip system and engineered safeguards functioning assumed to the extent allowed by considerations, such as the single failure criterion, in fulfilling this principle. This means that seismic Category I, Class IE (safety-related 4160 Vac Buses NB01 and NB02 and emergency diesel generators A and B), and IEEE qualified equipment, instrumentation, and components are used in the ultimate mitigation of the consequences of Conditions II (Faults of moderate frequency), III (Infrequent faults), and IV (Limiting faults- design basis accidents) events. The team determined that more inspection was necessary to resolve whether it was appropriate to evaluate emergency diesel generator operability using a 7-day mission time based on the restoration of offsite power as stated in FSAR Section 3.1.2, when no discussion of restoring offsite power was contained in the SER and FSAR Section 15. Since, further NRC clarification/interpretation of the existing guidance is necessary, the issue is considered an unresolved item pending further NRC review. (URI 05000483/2014008-03, Emergency Diesel Generator Operability Evaluations using a 7-Day Mission Time) |
| Site: | Callaway  |
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| Report | IR 05000483/2014008 Section 4OA5 |
| Date counted | Sep 30, 2014 (2014Q3) |
| Type: | URI: |
| cornerstone | Mitigating Systems |
| Identified by: | NRC identified |
| Inspection Procedure: | IP 71003 |
| Inspectors (proximate) | A Fairbanks C Henderson G Miller H Freeman T Hartman |
| INPO aspect | |
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Finding - Callaway - IR 05000483/2014008 | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
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Finding List (Callaway) @ 2014Q3
Self-Identified List (Callaway)
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