ML19242D607

LER 79-080/03L-0 on 790716:safety Features Actuation Sys Containment Radiation Detector Re 2005 Spiked & Tripped Channel 2 Containment Radiation Bistable.Caused by Component Failure.Detector Will Be Relocated Outside Containment

ML19242D607
Person / Time
Site:	Davis Besse
Issue date:	08/10/1979
From:	Eldred D TOLEDO EDISON CO.
To:	NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION III)
Shared Package
ML19242D606	List: ML19242D605 ML19242D607
References
DVR-79-112, LER-79-080-03L, LER-79-80-3L, NUDOCS 7908150504
Download: ML19242D607 (2)

Text

U.S. NUCLE AR HEGULATORY COMMI I RC FORM 366

.' /) LICENSEE EVENT REPORT l l l l l (PLEASE PRINT OR TYPE ALL REQUIRED INFORMATION)

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60 61 COC A ET N#.*d E R 66 63 EVENT DATE 14 75 REPORT DATE 80 EVENT DESCRIPTION AND PROB ABLE CONSEQUENCES h 'ntainment i the Safety Features Actuation System (SFAS) o 2 l On 7/16/79 at 0613 hours0.00709 days <br />0.17 hours <br />0.00101 weeks <br />2.332465e-4 months <br />, Radiation Detector RE 2005 spiked, tripping the SFAS Channel 2 Containment Radiation o 3i l At 0613 hours0.00709 days <br />0.17 hours <br />0.00101 weeks <br />2.332465e-4 months <br />, I The indication of RE 2005 immediately returned to normal.

o 4 l Bistable.

RE 2005 was declared inoperable placing the unit in Action State =ent of Technical

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Specification 3.3.2.1.b9. The bistable was lef t in the tripped condition. There was jno  !

e r so nnel. The other thrae j io 7 l danger to the health and safety of the public or station 1

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1 SFAS containment radiation instrument strings were operable. (NP-33-79-92) 30

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_ EVENT YEAR I7191 M 10 18 10 l W 1013I 23 29 IL I 30 BJ1 10 I 32 E 2J 24 26 27

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_ l35Z lg l36Z l@31 40 41 4 44 CAUSE DESCRIPTION AND CORRECTIVE ACTIONS h l The apparent cause is component failure of the detector, which is located within the j i o

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The root cause Uf this occurrence cannot be determined as the detector

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, 7 l is inaccessible during power operation. The detector will be relocated outside of j

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7 8 9 SO RY Of SCoVERY DESCRIPTION

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N'Ut- 237 f, N A*.'E OF PREP ARER David T. Eldred PHONE

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TOLEDO EDISON COMPANY DAVIS-BESSE NUCLEAR POWER STATION UNIT ONE

_ SUPPLEMENTAL INFORMATION FOR LER NP-33-79-92 DATE OF EVENT: July 16, 1979 FACILITY: Davis-Besse Unit 1 IDENTIFICATION OF OCCURRENCE: Safety Features Actuation System (SFAS) Channel 2 Containment Radiation Detector RE 2005 spiked Conditions Prior to Occurrence: The unit was in Mode 1, with Power (MWT) = 2625, and Load (Gross MWE) = 874.

Description of occurrence: On July 16, 1979, at 0613 hours0.00709 days <br />0.17 hours <br />0.00101 weeks <br />2.332465e-4 months <br />, SEAS Channel 2 Contain-ment Radiation Detector RE 2005 spiked (tripping the SFAS Channel 2 Containment Radia-tion Bistable) and returned to normal. Several prior spikes and resulting Channel 2 Containment Radiation Bistable trips had occurred in the late evening of July 15, 1979, and the morning of July 16, 1979. In each case, the indication of RE 2005 returned to normal and the trip was manually reset. Upon receiving the trip at 0613 hours0.00709 days <br />0.17 hours <br />0.00101 weeks <br />2.332465e-4 months <br /> on July 16, 1979, RE 2005 was declared inoperable. This placed the unit in Action Statement of Technical Specification 3.3.2.1.b9 which requires the operability of all four SFAS contai, ment radiation instrument strings in all modes. The SFAS Channel 2 containment radiacion bistable was left in the tripped state as required by the Action Statement.

The containment radiation instrunent s :cings associated with the other three SFAS channels were operable, meeting the minimum operational requirements-Designation of Apparent Cause of Occurrence: The apparent cause of this occurrence is component failure of the detector. The detector is located inside the containment and is therefore inaccessible during power operation so the exact mode of failure can-not be determined at this tbne.

Analysis of Occurrence: There was no danger to the health and safety of the public or to station personnel. The containment radiation monitoring instrument strings associated with the other three SFAS channels are operable. RE 2005 ialled in the high (safe) direction.

Corrective Action: The containment radiation bistable of SFAS Channel 2 remains in the tripped state as detector RE 2005 is inaccessible during power operation. Main-tenance Work Order IC-344-79 has been written to replace the detector when contain-ment access becomes possible. Facility Change Request 78-306, which will relocate the detect. ors outside containment to allow access during power operation is presently being implemented.

Failure Data: A previous failure of RE 2005 was reported in Licensee Event Report NP-33-78-140.

LER #79-080 t f.,

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