ML20138R006
| ML20138R006 | |
| Person / Time | |
|---|---|
| Site: | Catawba  |
| Issue date: | 12/20/1985 |
| From: | Tucker H DUKE POWER CO. |
| To: | Grace J NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION II) |
| References | |
| NUDOCS 8512300206 | |
| Download: ML20138R006 (2) | |
Text
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DUKE POWER COMPANY e.o. no x oo n,o cnAn w rre.u.c.2ea.4a nat. n.n:cxus
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Ed7?":L December 20, 1985
- s PWR - A/BC's TECil SUPPORT.
Dr. J.
Nelson Grace, Regional Administrato.
U. S. Nuclear Regulatory Commission AD - J. KNIGilT (ltr only)
Region II EB (BALLARD) 101 Marietta Street, NW, Suite 2900 EICSB (ROSA)
Atlanta, Georgia 30323 PSB (CAMMILL)
HSB (BERLINGER)
Ret Catawba Nuclear Station, Unit 1 FOB (BENAROYA)
Docket No. 50-413 Relief From Technical Specification LC.
Dear Dr. Grace:
Per our conversation with members of your staff on December 19, 1985, Duke hereby requests a 96 hour0.00111 days <br />0.0267 hours <br />1.587302e-4 weeks <br />3.6528e-5 months <br /> extension to the ACTION statement of Technical Specification 3/4.7.7 " Auxiliary Building Filtered Exhaust System".
The proposed relief request is a result of the need to replace the 1A Auxiliary Building Filtered Exhaust (VA) Fan Motor.
The amount of time to replace the motor exceeds the outage time allowed under Technical Specification 3.7.7.
The motor was identified as defective at 5:54 p.m. on December 18, it was determined that the motor would have to be totally replaced around 10:00 a.m. on December 19, 1985.
A replacement was located and disassembly begun.
The amount of time needed to install the replacement motor and conduct the required re-testing will exceed the allowed outage time of 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br />.
Providing an additional 96 hours0.00111 days <br />0.0267 hours <br />1.587302e-4 weeks <br />3.6528e-5 months <br /> will allow the repairs to be made and the system to be restored to operability.
The sole function of the VA system is to filter the airborne radioactivity released from the coolant leakages associated with the ECCS equipment in the Auxiliary Building, following a LOCA involving severe fuel damage.
The off-site doses associated with ECCS leakages post LOCA have been evaluated in the Catawba FSAR (Section 15.6.5 and Table 15.6.5-10).
The contribution of ECCS leakages to the off-site doses, post LOCA, is not significant with or without VA filtration before release to the environment.
Furthermore, during the period of inoperability of the A Train exhaust fan, the 100% capacity, totally redundant B Train fan and filter will be operable and capable of filtering the safety train ECCS pump rooms for unit one.
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Dr. J. N31 con Greca, R2gional Adminictrator December 20, 1985 Page Two I
The duration of operation without Unit I having its VA Filtered Exhaust System operable would be small (96 hours0.00111 days <br />0.0267 hours <br />1.587302e-4 weeks <br />3.6528e-5 months <br />).
The probability of occurrence of a LOCA during this time is extremely small.
For example, the LOCA frequency for a large break with potential for core heatup is 4.7xE-5 per reactor year (see Sequoyah l
1 RSSMAP-NUREG/CR-1659).
The probability of a large break LOCA during a 96 hour0.00111 days <br />0.0267 hours <br />1.587302e-4 weeks <br />3.6528e-5 months <br /> period is less than 9.0xE-7.
The probability of excessive ECCS leakages subsequent to a LOCA is even smaller.
Therefore, granting of this request would not pose undue risk to the health and safety of the public.
An equally important reason for granting the proposed change is that one thermal cycle on the reactor and associated systems would be avoided.
This has real benefits in terms of availability, component lifetime and safety.
A permanent change to the Catawba Technical Specifications will be pursued.
Justification will be provided which will allow the VA System to be inoperable for up to 7 days.
This allowed outage time is consistent with the NRC's Standard Technical Specifications, Revision 4 and Draft Revision 5.
Should there be any questions or if additional information is required, please advise.
Very truly yours, 44 b L Hal B. Tucker a
RWO sib cci dMr. Harold R. Denton, Director 1
j Office of Nuclear Reactor Regulation U. S. Nuclear Regulatory Commission Washington, D. C.
20555 NRC Resident Inspector Catawba Nuclear Station i
i.