ML20195D116
| ML20195D116 | |
| Person / Time | |
|---|---|
| Site: | Sequoyah  |
| Issue date: | 05/27/1986 |
| From: | Wallace P TENNESSEE VALLEY AUTHORITY |
| To: | NRC OFFICE OF ADMINISTRATION (ADM) |
| References | |
| 86-05, 86-5, NUDOCS 8606020116 | |
| Download: ML20195D116 (2) | |
Text
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~p TENNESSEE VALLEY AUTHORITY Sequoyah Nuclear Plant Post Office Box 2000 Soddy-Daisy, Tennessee 37379 May 27, 1986 U.S. Nuclear Regulatory Commission Document Control Desk Washington, DC 20555 Gentlemen:
TENNESSEE VALLEY AUTHORITY - SEQUOYAH NUCLEAR PLANT UNIT 1 - DOCKET NO.
50-327 - FACILITY OPERATING LICENSE DPR SPECIAL REPORT 86-05
- The enclosed special report provides details concerning the inoperability of the carbon dioxide fire protection system for greater than 14 days. This event is reported in accordance with Sequoyah unit 1 Technical Specification 3.7.I1.3.
Very truly yours, TENNESSEE VALLEY AUT11GRITY OR.wdfw P.-R. Wallace Plant Manager Enclosure cc (Enclosure):
J. Nelson Grace, Regional Administrator U.S. Nuclear Regulatory Commission Suite 2900 101 Marietta Street, NW Atlanta, Georgia 30323 Records Center Institute of Nuclear Power Operations Suite 1500 1100 circle 75 Parkway Atlanta, Georgia 30339 NRC Inspector, Sequoyah Nuclear Plant 8606020116 860527 PDR ADOCK 05000327 S
PDR 7
off An Equal Opportunity Employer
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~9 SPECIAL REPORT 86-05 SEQUOYAH NUCLEAR PLANT UNITS 1 AND 2 Event Description and Cause On April 19, 1986, during the performance of Surveillance Instruction (SI)-237.1, " Powerhouse Carbon Dioxide Fire Protection System Test," a leak was discovered in the actuation system piping in the 24-ton carbon dioxide (CO ) vault.
Further investigation determined that the leak was 2
significant. The main header isolation valve was closed, and the system was declared inoperable. Limiting Condition for Operation (LCO) 3.7.11.3.a was entered and fire watches were established for the areas protected by the CO system. A work request (WR). was submitted, the pilot valves were 2
repaired, and the system was returned to operable status on the morning of April 20, 1986. The SI performance was restarted on April 21, 1986, additional leaks were discovered, the system was tagged out, and LCO
- 3. 7.11.3.a was reentered. Continuous fire watches were established and will remain in place until the CO system is returned to normal. This 2
technical specification requires that if the system is not returned to operable status within 14 days, a special report is required to outline the action taken, the cause of the inoperability, and the schedule for returning the system to service. Due to the unavailability of repair parts and the hazard presented to employees working in the arees protected by this system if the system was returned to service without necessary repairs, the CO system will remain out of service until repairs are cocr 2
plete. The areas affected are the computer room and both units 1 and 2 auxiliary instrument rooms. Both units were in mode 5 during this occurrence.
The leaks were determined to be through the rubber disc valve seats on the main selector valves and through the pilot valves. The rubber disc had hardened, and it had some small cuts on it.
This was due to normal wear and aging. Other parts are being rebuilt or replaced as needed.
SI-237.1 is required to be performed every 18 months.
Before this occur-rence, a preventative maintenance program was not in place. However, a leak check is performed whenever the header is charged, and the storage tank is checked every seven days as required by technical specifications.
i Corrective Action A service contract for inspection and repair has been awarded. The con-tractor was onsite during the week of May 12, 1986, to completely check out the CO, system and to make necessary repairs to return the system to operable status. The needed parts have been ordered, and the C0 system is expected to be operable within six weeks. Apreventativemaiktenance program will be established and initiated by November 21, 1986. Continuous fire watch coverage will be maintained until functional capability of the CO system is established.
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