ML19260D037

LER 80-004/03L-0:on 800107,control Rod 5-11 Absolute Position Indication Declared Inoperable Due to Fluctuating Signals.Possibly Caused by Isolation of Position Indication Cabling & Electrical Penetration

ML19260D037
Person / Time
Site:	Davis Besse
Issue date:	02/04/1980
From:	Werner J TOLEDO EDISON CO.
To:	NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION III)
Shared Package
ML19260D009	List: ML19260D008 ML19260D037
References
LER-80-004-03L, LER-80-4-3L, NUDOCS 8002070280
Download: ML19260D037 (2)

Text

U. S. NUCLE, AR HEGUL AT ORY co".tMISSION NFC FOT'f.1 ZO (774 b LICENSEE EVENT REPORT

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EVENT OESCRIPTION AND PROBABLE CONSEQUENCES h j l o l 2 ) i On January 7,1980 at 2115 hours0.0245 days <br />0.588 hours <br />0.0035 weeks <br />8.047575e-4 months <br /> Control I;od 5-11 absolute position indication (API) l

[y[3l l was declared inoperable.due to fluctuating signals which caused numerous " asymmetric o 3, l rod" alarms. This placed the unit in the action statement of T.S. 3.1.3.3 which re- l j

lo ) ,) [ quired the position of the control rod to be verified by actuating one of its zone The rod was verified at its 100% withdrawn position, and the  ;

g i reference indicators.

There was no danger to the public or; J o l 7 ) l position indication placed in asymmetric bypass.

f ola i i station personnel. The ' control rod never deviaced from its intended position._ _

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OCCUR R E f.CE REPORT REVISION SE QUENTI AL REPOR T NO. CODE TYPE N O.

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_ 21 22 LOVFON E *; T ACTIO*4 f u r',H E FFFECT SHI)T D OWN ATT AC HY E N T P;P A D 4 PRIVE COVP.

A C T F,1 vt THL,0 HOURS SUBYe t T ED FORM SUS. SUPPlit4 UANUrACTL-EG TAKEN ON PL ANT LxJSLxjg iz l@ LzJ@ 101010 I l41Y l@ l42Y l@ lNl@ lXlXlXlX[g Ju 3# 40 43 44 47 3 'J J4 JJ CAUSE DESCRIPTION AND CONNECTIVE ACTIONS h i 11LoJ l The exact cause In still undetermined but has been isolated to the position indication; I

[ t ij i cabling and the electrical penetration between the outer penetration terminal board Data from a test conn- l

_ It 171 l and the top of the control rod position indication assembly.

i a l ection which was installed in December 1979 is currently being evaluated by station [

_ LLLJ l and vendor personnel. This should give direction for further troubleshooting activitv[. gg 7 8'3 F ACillTY UE THOD OF

% POWER OTHE R STATUS DISC OV E R Y DISCOVERY DESCRIPTION 32 STATU3 ii5 Wh l6 l2 l3 lhl NA 1 11 44 l lA l@l operator observation 45 46 80 l

ACTtVliv CC TENT AMOUNT OF ACTIVITV LOCATION C' RE LE ASE RELE AMD 08 RELE ASE l

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NUU8ER TYPE DESCRIPTION

__ j i e I o I o I o !@l z l@l NA 80 PE RSONNE L INJU IES JI J k NUYBE R C ESCR6P TION i _ EED819 D i e i o @i Ni 7 it 12 80 LOSS OF On O AVAr.E TO F ACILITY . Z'o L7.J@l NA IVPE CESCRiPTION 8002070 280 80 i 7 8 9 10 8UB LICI T Y

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J: o t ;5U E D Luj S NA CESCMPTiqN i i i- i i i i i i i r rphii f48 63 i 8 9 60 DVR 80-009 NAME OF PREPA9ER PHONE: a

TOLEDO EDISON COMPANY DAVIS-BESSE NUCLEAR POWER STATION UNIT ONE SUPPLEMENTAL INFORMATION FOR LER NP-33-80-07 DATE OF EVENT: January 7, 1980 FACILITY: Davis-Besse Unit 1 IDENTIFICATION OF OCCURRENCE: Control Rod 5-11 Absolute Position Indication (API) fluctua tions Conditions Prior to Occurrence: The unit was in Mode 1, with Power (MRT) = 637, and Load (Gross MWE) = 212. Description of Occurrence: On January 7,1980, at 2115 hours Control Rod 5-11 API was declared inoperable due to fluctuating signals which caused numerous " asymmetric rod" alarms. All API channels are required to be operable and capable of determining control rod position within + 6.5% in Modes 1 and 2. This placed the unit in the action statement of Technical Specification 3.1.3.3 which required the position of the control rod to be verified by actuating ce of its zone reference indicators. The rod position was verified at its 100% withdrawn position, and the rod position indication was placed in asymmetric bypass. Designation of Apparent Cause of Occurrence: The exact cause of this occurrence is still undetermined but has been isolated to the position indication cabling and the electrical penetration between the outer penetration terminal board and the top of the control rod position indication assembly. Investigation is continuing at this time with vendor assistance. Analysis of Occurrence: There was no danger to the health and safety of the public or to station personnel. The control rod never deviated from its irtended position, only the API was faulty. Corrective Action: During the last shutdown in December,1979, and with vendor assistance, a test connection under Facility Change Request 79-424 was placed between the position indication (PI) assembly and its associated cabling to moni-tor the various voltages at that point. This was done as a corrective action to the same type of occurrence reported under Licensee Event Report NP-33-79-141. From the data collected under Work Request IC-05-80, the cause of the voltage fluctuations does not appear to be related to the PI assembly. The data is currently being evaluated by station and vendor personnel. Based on this evalua-tion, a decision on how to continue troubleshooting the problem, when containment is again ac:essible, will be made. Failure Data: There have been previous failures of control rod APIS. Control Rod 5-ll's current symptoms were previously . reported in Licensee Event Report NP-33-79-141.

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