ML19254F957

LER 79-101/03L-0:on 791017,safety Features Actuation Sys Channel 2 Radiation Detector Re 2005 Spiked Tripping Channel 2 Containment Radiation Bistable.Caused by Component Failure of Detector.Failed Detector Replaced

ML19254F957
Person / Time
Site:	Davis Besse
Issue date:	11/13/1979
From:	Eldred D TOLEDO EDISON CO.
To:	NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION III)
Shared Package
ML19254F953	List: ML19254F952 ML19254F957
References
LER-79-101-03L, LER-79-101-3L, NUDOCS 7911190521
Download: ML19254F957 (2)

Text

U. S. NUCLE AR REGULATORY COMMISSION 3C FORM 366 (7 77)

LICENSEE EVENT REPORT CONTROL BLOCK: l 1

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lh (PLEASE PRINT OR TYPE ALL REQUIRED INFORMATION) lo l t8 l3 l0 l LICENSEE H l DCODE l B l S l 1 l@l 0 l0 l-UCENSE l 0 l0 lN lP lF l- l025 l 326l@lLICENSE 4l 1lTYPE ll 1lJO 1 @l l

St car 68 7 14 15 NUMdER CON'T 0 1 5$RCE60l L l@l610 5 l 0 l- l 0 l 3 l 4 l 6 63}@l631 l 0EVENT l1 l DATE 7 l 7 19 74]@l 1 1l 1l 317l 9l@ 80 15 REPORT DATE 7 8 DOCK ET NUMBER EVENT DESCRIPTION AND PROBABLE CONSEQUENCES h o 2 lOn October 17, 1979 at 1410 hours0.0163 days <br />0.392 hours <br />0.00233 weeks <br />5.36505e-4 months <br />, Safety Features Actuation System (SFAS) Channel 2 0 3 l Radiation Detector RE 2005 spiked tripping SFAS Channel 2 containment radiation bi- l o 4 [ stable. This placed the unit in the Action Statement of T.S. 3.3.3.1.b9 which requirej

[TlT) l the f ailed section of the channel be lef t in the tripped state. There was no danger j l 016 l l to the health and safety of the public or station personnel. The containment radia-- l l 0 l 7 l l tion instrument strings associated with the other three SFAS Channels acre operable [

0 s [which u. sts the minimum operational requirements. (NP-33-79-118) 80 I

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44 47 CAUSE DESCRIPTION AND CORRECTIVE ACTIONS h i O lThe cause of the occurrence was component failure of the detector. Under Maintenance l li g i j [ Work Order (WO) IC-464-79, the failed detector was replaced. The r m detector was

, 7 l declared operable by the successful performance of ST 5031.01 at 0515 hours0.00596 days <br />0.143 hours <br />8.515212e-4 weeks <br />1.959575e-4 months <br /> on October l- 3 l20, 1979. WO IC-466-79 was issued to repair the failed detector.

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% POWER oTHER STATUS ISCO RY DISCOVERY DESCRIPTION ST JS 1 s lD l@ l 0 ] 0 l 0 l@l NA l lAl@l Operator observation l ACTIVI TY CO TENT AMOUNT OF ACTIVITY LOCATION OF RELEASE RELEASED OF RELE ASE NA 1 6

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2 o ISSUE

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7 8 3 David T. Eldred 419-259-5000, Ext. 237 DVR 79-153 ngggoppngpgngg PHONE: {

TOLEDO EDISON COMPANY DAVIS-BESSE NUCLEAR POWER STATION UNIT ONE SUPPLEMENTAL INFORMATI0M FOR LER NP-33-79-118 DATE OF EVENT: October 17, 1979 FACILITY: Davis-Besse Unit 1 IDENTIFICATION OF OCCURRENCE: Safety Features Actuation System (SFAS) Channel 2 Con-tainmer.t Radiation Detector RE 2005 inoperable Conditions. Prior to Occurrence: The unit was in Mode 3, with Power (MWT) = 0, and Load (Gross MWe) = 0.

Description of Occurrence: On October 17,1979 at 1410 hours0.0163 days <br />0.392 hours <br />0.00233 weeks <br />5.36505e-4 months <br />, SFAS Channel 2 Radia-tion Detector RE 2005 spiked (tripping SFAS Channel 2 containment radiation bistable) and returned to normal. The spiking was over full range of the readout and RE 2005 was declared inoperable. This placed the unit in the Action Statement of Technical Specification 3.3.3.1.b9 which requires the operability of all four SFAS containment radiation instrument strings in all modes. The SFAS channel 2 containment radiation The bistable was lef t in the tripped state as required by the Action Statement.

containment radiation instrument strings 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 failed detector is being examined by the Instrument and Control shop and as of this time the problem has not been pinpointed.

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 opera 51e. RE 2005 failed in the high (safe) direction.

Corrective Action: Under Maintenance Work Order IC-464-79, the detector was replaced.

The new detector was declared operable by the successful performance of ST 5031.01 at 0515 hours0.00596 days <br />0.143 hours <br />8.515212e-4 weeks <br />1.959575e-4 months <br /> on October 20, 1979. Maintenance Work Order IC-466-79 was issued to troubleshoot and repair the failed detector. The low range board and the auxiliary board in the detector were found to be defective. These boards were replaced and a detector calibration was accomplished. The detector was returned to stock as a spare and the failed boards were returned to Victoreen Company for repair. The maintenance work order was completed on Urvember 5 and closed on November 7, 1979.

Failure Data: Previous failures of RE 2005 were reported in Licensee Event Reports NP-33-78-140, NP-33-79-92, and NP-33-79-103.

LER #79-101 1345 339