ML20070F834
| ML20070F834 | |
| Person / Time | |
|---|---|
| Site: | Sequoyah  |
| Issue date: | 07/14/1994 |
| From: | Powers K TENNESSEE VALLEY AUTHORITY |
| To: | NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM) |
| References | |
| 94-06, 94-6, NUDOCS 9407190190 | |
| Download: ML20070F834 (3) | |
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Tennenn Visticy At>t*xsof, Post 06ce Bax 2M)0. Styktf Dasy. Tennessee 373 000 Ken Powers Vice Pren>&,nt. Secpoyah Ns.*uir Fbnt July 14, 1994 U.S.
Nuclear Regulatory Commission ATTN:
Document Control Desk Washington, D.C.
20555 Gentlemen:
In the Matter of
)
Docket No. 50-328 Tennessee Valley Authority
)
SEQUOYAH NUCLEAR PLANT (SQN) - UNIT 2 - FACILITY OPERATING LICENSE DPR TECHNICAL SPECIFICATION (TS) 3.3.3.8 - SPECIAL REPORT 94-06 The enclosed special report provides details concerning the inoperability of the fire detection instrumentation in Fire Zone 353 for the Unit 2 containment lower compartment cooler area.
This report is being submitted in accordance with Technical Specification Action Statement 3.3.3.8.(b).
If you have any questions concerning this submittal, please telephone C. H. Whittemore at (615) 843-7210.
SincereJy, Kn owers Enclosure cc:
See page 2 1
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+ty 9407190190 940714 PDR ADOCK 05000328
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Nuclear Regulatory Commission Page 2 July 14, 1994 cc (Enclosure):
Mr.
D.
E.
LaBarge, Project Manager U.S.
Nuclear Regulatory Commission One White Flint, North 11555 Rockville Pike Rockville,-Maryland 20852-2739 NRC Resident Inspector Sequoyah Nuclear Plant 2600 Igou Ferry Road Soddy-Daisy, Tennessee 37379-3624 Regional Administrator U.S.
Nuclear Regulatory Commission Region II 101 Marietta Street, NW, Suite 2900 Atlanta, Georgia 30323-2711
ENCLOSURE SEQUOYAH NUCLEAR PLANT UNIT 2 SPECIAL REPORT 94-06 Description of Condition On May 31, 1994, with Unit 2 in Mode 1, the photoelectric detection instrumentation in the Unit 2 lower compartment cooler areas was declared inoperable, and Limiting condition for Operation (LCO) 3.3.3.8 was entered.
Trouble alarms were acknowledged on Panel 630 for Fire Zone 353.
Several attempts to identify and resolve the problem and maintain the operability of the fire detectors were unsuccessful.
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decision was made to repair the detectors during the Unit 2 Cycle 6 outage because of ALARA (as low as reasonably achievable) radiation dose considerations. As a result of this decision, the time required to restore the instruments to operable status exceeded the technical specification allowable timeframe for fire detection instrumentation.
Cause of Condition The photoelectric detectors in the lower compartment cooler areas brought in the trouble alarms on the pyrotronics system (Panel 630).
This alarm is a supervisory circuit that transmits low current signals and monitors the resistance in the detection zone to determine circuit integrity.
Troubleshooting of the detector circuit identified a high electrical resistance. The cause for the high resistance has not been determined.
Corrective Action In accordance with LCO 3.3.3.8 Action Statement (a), the Unit 2 lower compartment air temperature is being monitored at least once every hour until the detectors can be restored to operable status. A work request has been written arid scheduled for the Unit 2 Cycle 6 refueling outage.
The Unit 2 Cycle 6 outage began on July 4, 1994, and is scheduled to be completed on Octobe r 17, 1994.