ML19253A853

LER 79-089/03L-0:on 790811,single Failure Analysis Sys Channel 2 Containment Radiation Detector Re 2005 Spiked & Tripped Bistable.Re 2005 Declared Inoperable.Caused by Vibration in Area of Detector

ML19253A853
Person / Time
Site:	Davis Besse
Issue date:	09/06/1979
From:	Eldred D TOLEDO EDISON CO.
To:	NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION III)
Shared Package
ML19253A852	List: ML19253A851 ML19253A853
References
LER-79-089-03L, LER-79-89-3L, NP-33-79-103, NUDOCS 7909110541
Download: ML19253A853 (3)

Text

u.S. NUCLE AR REGULATORY COMMISSION NRC FORM 366 (7-77)

. LICENSEE EVENT REPORT

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(PLE ASE PRINT OR TYPE ALL REQUIRED INFORMATION)

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_7 8 60 61 DOCKET NUYBER EVENT DESCRIPTION AND PROBABLE CONSEQUENCES h

- l o [ 2 l l On, August 11, 1979 at 1430 hours0.0166 days <br />0.397 hours <br />0.00236 weeks <br />5.44115e-4 months <br />, SFAS Channel 2 Containment Radiation Detector RE 2004 RE 2005 was declared inopera- l l o 131 i spiked (tripping the bistable) and returned to nomal.

l o 14 l lble, and the unit was placed in the Action Statement of T.S. 3.3.2.1.b.9 which requireq

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o s lall four instrument strings operable in all modes. The SFAS Channel 2 Containment l There was no danger to the health l

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o e l Radiation Bistable was lef t in the tripped state.

The radiation mor'toring instrument l o 7 land safety of the public or to station personnel.

(NP-33-79-103)

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_ l 3 l o l lThe spiking was attriiuteci to vibration in the area of the detector which causes flex- l

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g,gij ling of the ion chamber connectors to the high and low range boards. Victorcen indi-A new detector

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TOLEDO EDISON COMPANY DAVIS-BESSE NUCLEAR POUER STATION UNIT ONE SUPPLEMENTAL INFORMATION FOR LER NP-33-79-103 DATE OF EVENT: August 11, 1979 FACILITY: Davis-Besse Unit 1

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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 (m.7) = 2758, and Load (Gross MWE) = 914.

Description of Occurrence: On August 11, 1979 at 1430 hours0.0166 days <br />0.397 hours <br />0.00236 weeks <br />5.44115e-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 spikes occurred in the fifteen minutes prior to the channel trip. Upon receiving the trip, RE 2005 was declared in-operable. This placed the unit in the Action Statement of Technical Specification 3.3.2.1.b9 which requires the operability of all four SFAS containment radiation in-strument strings in all modes. The SFAS Channel 2 containment radiata.on bistable was left in the tripped state as required by the Action Statement. The containment radiation instrument strings associated with the other three SEAS channels were opera-ble, meeting the minimum operational requirements.

Designation of Apparent Cause of Occurrence: The tripping of SEAS Channel 2 was caused by the spiking of Containment Radiation Detector RE 2005. The cause of the spiking has been attributed to vibration in the area of the detector waich causes flexing of the ion chamber connectors to the high and low range boards. Victorcen has indicated this flexing can generate a small voltage which would cause the spiking problem; testing in our Instrument and Control chop substantiates this.

Analysis of .0ccurrence: 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 SEAS channels were operable. RE 2005 failed in the high (safe) direction.

Corrac.tive Action: A neu detector was calibrated and installed per MWO-IC-383-79.

SFAS Channel 2 (Containment Radiation) was declared operable at 1750 hours0.0203 days <br />0.486 hours <br />0.00289 weeks <br />6.65875e-4 months <br /> on August 15, 1979, by successful performance of Surveillance Test ST 5031.01 on RE 2005 which removed the unit from the Action Statement. Toledo Edison and Victoreen are investi-This is the first gating the addition of vibration dampening material in the detector.

detector to be moved from its original high temperature environment to stop the failures caused by high temperature. Other detectors will not be moved until this vibration problem is resolved.

LER #79-089 S373130

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TOLEDO EDISON COMPAhT DeWIS-bESSE NUCLEAR POWER STATION L"11T ONE PAGE 2 SUPPLEME'4TAL INFOR'!ATION FOR LER NP-33-79-103 Feilure Data. Previous failures of RE 2005 have been reported in Licensee Event Report NP-33-78-140 and NP-33-79-92.

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