ML20041C046
| ML20041C046 | |
| Person / Time | |
|---|---|
| Site: | Rancho Seco |
| Issue date: | 01/29/1982 |
| From: | Haughey M, Padovan M NRC |
| To: | |
| Shared Package | |
| ML20041C045 | List: |
| References | |
| NUDOCS 8202260081 | |
| Download: ML20041C046 (2) | |
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SAFETY EVALUATION BY THE OFFICE OF NUCLEAR REACTOR REGULATION RANCHO SEC0 GENERATING STATION, UNIT NO. 1 DOCKET N0. 50-312 REACTOR BUILDING PURGING Sacramento Municipal Utility District's (SfiUD's) January 28, 1982 letter requests NRC approval to pemit purging of the containment for a period of thirty-six hours, beginning January 29, 1982 The purpose of the purge will be to reduce the airborne activity and atmospheric temperature to values acceptable for entry by plant personnel. Entry into containment is necessary to perform safety-related snubber inspections in accordance with the Rancho Seco Technical Specifications, Section 3.12.
SMUD's January 18, 1980 letter committed to limit containment purging to times when the reactor is at cold shutdown or refueling shutdown.
The NRC's May 11, 1981 letter further required that NRC approval must be obtained by SMUD before purging is permitted. The following evaluation discusses the acceptability of purging at Rancho Seco.
Evaluation In numerous telephone conversations with menbers of the staff, during the week of January 25, 1982, SMUD discussed utilizing the following 66" Allis-Chalmers valves to purge containment.
Valve Number Description Valve Operator SFV 53503 Surge Inlet, Aux. Building Side air / spring SFV 53504 Purge Inlet, Reactor Building Side motor SFV 53604 Purge Outlet, Aux. Building Side air / spring SFV 53605 Purge Outlet, Reactor Building Side motor The NRC review verified that the 66" air-operated purge valves could close following a loss-of-cooldt accident (LOCA) if the valves are blocked at the 60 open position (90" being full open). Tlie Rancho Seco Resident Inspector has verified that blocking of these valves at Rancho Seco is complete.
In reviewing the 66" motor operated valves, it was discovered that normal purge inlet valve SFV-53504 was not fully qualified due to configuration problems (disc rotation direction).
Thus, the purge inlet train, containing valves SFV 53503 and SFV 53504, can not be used for this purge and must be closed shut at all times except during cold shutdown or refueling. Motor operated normal purge outlet valve SFV 53605 was found to be capable of closing after a LOCA from a 45* open position. Consequently, the reactor building purge outlet train, containing valves SFV 53604 and SFV 53605, can be used for the proposed purge.
8202260081 820129 PDR ADOCK 05000312 P
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, In their January 28, 1982 letter, SMUD proposed to use the 12" equalization line, containing valves SFV 53610 and SFV 53603, as the ventilation inlet.
The staff has determined that these 12" valves can close following a LOCA.
As limited purging is needed to 1) permit inspection of safety-related snubbers, and 2) will aid in reducing radiation exposure of plant personnel, the staff hereby approves purging of the containnent atmosphere with the reactor at full power for a period of 36 hours4.166667e-4 days <br />0.01 hours <br />5.952381e-5 weeks <br />1.3698e-5 months <br /> beginning on January 29, 1982. Prior to returning the reactor to a hot standby condition, all purge and vent valves shall be returned to the closed position.
Purging is acceptable for the interim period of 36 hours4.166667e-4 days <br />0.01 hours <br />5.952381e-5 weeks <br />1.3698e-5 months <br />. Long term acceptability is contingent upon additional review to be performed at a later date.
Dated: January 29, 1982 Contributors to this SER were Mark Padovan and Mary Haughey.
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