ML19345G599

LER 79-101/03X-1:on 791017,safety Features Actuation Sys Channel 2 Radiation Detector Re 2005 Spiked,Tripping Channel 2 Radiation Bistable.Caused by Defective Low Range & Auxiliary Boards in Detector.Detector Replaced

ML19345G599
Person / Time
Site:	Davis Besse
Issue date:	03/31/1981
From:	Eldred D TOLEDO EDISON CO.
To:	NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION III)
Shared Package
ML19345G598	List: ML19345G597 ML19345G599
References
LER-79-101-03X, LER-79-101-3X, NUDOCS 8104070580
Download: ML19345G599 (2)

Text

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3C FORP.! 36G (7 77) .

LICENSEE EVENT REPORT (PLEASE PRINT OR TYPE ALL REQUIRED INFORMATION) l lh CONTROL BLOCK: l l l l l I ti

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l0l1l- 63 EVENT OATE 14 75 DATE 7 8 60 61 COCKET NLP.*BER EVENT DESCRIPTION AND PROB ABLE CONSEQUENCES h J, Safety Features Actuation Systcm (SFAS) Channel 2 _ j lo 12 l lOn October 17. 1979 at 1410 hou l

lola) 1 Radiation' Detector RE 2005 spiked tripping SFAS Channel 2 ccntainment radiation bi-0 4 Istable. This placed the unit in the Action Statement of T.S. 3.3.3.1.b9 which require l There was no danger l lals) Ithe failed section of the channel be icft'in the tripped state.

lo is I lto the health and safety of the public or station personnel. The containment radia-l l

strings associated with the other three SFAS Channels were operable .

l 0 l 7 l l tion instrument l

f o la l Iwhich meets the minimum operational requirements. (NP-33-79-118)

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8. OCCURRENCE PEPORT SEoVENTIAL TYPE N O.

REPORT No. CODE ll @ ,atgr tf H/RO u

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J@LDJ@ IZ l@ I36Z I@ 37 40 42 44 47 33 34 35 CAUSE DEtCRIPTION AND CORRECTIVE ACTIONS h -

Under Maintenance l g lThe cause of the occurrence was component failure of the. detector.

I l ,1 : 1 j'Jork Order (MUO) IC-464-79, the failed detector was replaced. The new detector was 5031.01 at 0515 hours0.00596 days <br />0.143 hours <br />8.515212e-4 weeks <br />1.959575e-4 months <br /> on 0ctoberl.

g,g,1 l declared operable by the successful performance of ST the low l20, 1979. MNO IC-466-79, issued to repair the failed detector, found that l

l g l range board and' the auxiliary board in the detector were defective. 80

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-D$ fY DISCOVERY DESCRIPTION STA *.POWER OTHER STA fUS l

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,7 8 9 LOCATION oF PELEASE PELEASED OF RELEASE AMOUNT OF ACTIVsTY NA l NA l 'l 1 6 IZ I @ l ZMl

' ' PERSONNEL EXPOS ES NU'38 E R TYPE DESCRIPTION j.

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.6 TOLEDO EDISON COMPANY DAVIS-BESSE NUCLEAR POWER STATION UNIT ONE SUPPLEMENTAL INFORMATION FOR LER NP-33-79-118 DATE OF EVENT: 0ctober 17, 1979 FACILITY: ravis-Besse Unit 1 IDENTIFICATION OF-0CCURRENCE: -Safety Features Actuation System (SFAS) Channel 2 Con-

-tainment Radiation Detector RE 2005 inoperable i

i The unit was in Mode 3, with Power (MWT) = 0, and

-Conditions Prior to Occurrence:

Load (Cross 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 ovar full range of the readout and RE 2005 l

was declared inoperable. This placed the nait 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 t

were operable, meeting the minimum operational requirements, f

e The apparent cause of this occurrence Designation of Apparent Cause of Occurrence: Ext.mination by the Instrument and Control shop-

.1 is component failure of the detector. ~

i found that the low: range board and the auxiliary board in the detector were defect ve,

-Analysis of Occurrence: There was'no' danger to the health and safety of the public i

i or to station personnel. . The- containment radiatio 1 monitoring instrument strings RE 2005 failed in the associated with the other ,three SFAS channels are operable.

~

i. hi d (safe) direction.

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

5031.01 at

-The new detector.was declared operable by.the successful performance of ST 0515 hours0.00596 days <br />0.143 hours <br />8.515212e-4 weeks <br />1.959575e-4 months <br /> on October 120, 1979. Maintenance Work Order IC-466-79 was issued to i

The low range board and the auxiliary

. troubleshoot and repair the f ailed ~ detector. These boards were replaced and a board detectorincalibration the-detector'were found to be defective.The detector was returned to stoc was accomplished.

f spare. The. maintenance work order was closed on November.7, 1979.

f, Failure Data: Previous ' failures 'of RE '2005 were reported in Licensee Event Reports t.

l:

NP-33-78-140, NP-33-79-92, and NP-33-79-103.

i LER #79-101

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