ML19242D300

LER 79-079/03L-0 on 790712:while Repositioning Group 8, Absolute Position Indication for Rod 4 Shifted from 25% to 0% Position.Caused by Oxide Film Buildup on Reed Switch Contacts.Corrective Maint Performed

ML19242D300
Person / Time
Site:	Davis Besse
Issue date:	08/09/1979
From:	Naylor R TOLEDO EDISON CO.
To:	NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION III)
Shared Package
ML19242D286	List: ML19242D285 ML19242D300
References
LER-79-079-03L, LER-79-79-3L, NUDOCS 7908140797
Download: ML19242D300 (2)

Text

U. S. NUCLE AR REGULATOR ..

NRC FORM 366 (7-7 7 )

LICENSEE EVL a REPORT

'

CONTROL BLOCK: l l l l l l l (PLEASE PRINT OR TYPE ALL REQUIRED INFORMATION) 1 O F l- l0 l3 @l4 1UCENbE [1 l1T YPE l1JJ@lSI LAI5dl lg

@l0'[0 - l0 0 N P lo lil8 9 0lHLICENSEE 7

D B lS CODE 1

14 15 LICEN5E A.UYdLH 23 Ju CON'T 0 1 5$RCE lLlg 015l0l-l0l3l4l6 lgj0(7(1EVENT

" "

od 63 l2 OATEl7 l9 l@[0 l8 l0 l9 l7 l9 j@

14 75 REPORT D AT E 8J 1 8 60 61 DOC A E T NUY6ER EVENT DESCRIPTION AND PROBABLE CONSEQUENCES h On 7/12/79 at 0415 hours0.0048 days <br />0.115 hours <br />6.861772e-4 weeks <br />1.579075e-4 months <br /> while repositioning Group 8, the absolute position indica- l lo l2l l 10131 tion (API) for Rod 4 of Group 8 shifted from the ?5% withdrawn position to the 0% l o a i Position. Thia placed the unit in the Action Statement of T.S. 3.1. 3.3 which re- l quires all API channels to be operable in Modes 1 and 2. There was no danger to the [

o 5 l health and saf ety of the public or station personnel. The relative and the group  ;

lo ls I i o 7 i Position indications were operable the entire time the API was inoperable. [

.

,

o y , (NP-3 3-79-100) 80 7 8 0 CAUSE COVP. VALVE SYSTEM CAUSE SUSCODE SUBOODE CODE CODE SUSCODE COY-CNENT CODE

_

o 9 8

I R l B l@ lE l@ l Al@ l Il Nl Sl Tl Rl Ulh l E l@ l Zl@

9 10 11 12 T3 id 19 40 REVISION 7

SEQUENTI AL oCCU R RE NCE REPORT CODE TYPE N o.

REPORT NO.

@ ay.g; LER RO _ EVENT YE AR I 71 91 l-l 1017191 1-1 Lo l 3 IL l l-l l0l 32 24 21 28 29 30 31

_ 21 22 23 Jti N P R D -4 PRIVE CCYP. COYPONENT A TT A C H M E N T A CTION FUTURE EFFECT SH U T O OV.N SUPYl TT E D F OR M d;.,ts. SUPPLI E R YANUFACTUHE4 TAKEN ACllON ON PL A'4T YETHOD r< CURS 22 10 10 10 l I Yl@ U@ lNlg lDj1l5 0lg IBl@lZI@ 34 IZ h

l@ IZ l@

ao 3/ 4J I

41 42 43 44 af 33 CAUSE DESCRIPTICN AND CORRECTIVE ACTIONS h i o l The apparent cause is that of oxide film buildup on the reed switch contacts. As the]

li li j rod withdrawal continued past the faulty reed switch, the API indication returned to [

-

, 7 l normal, removing the unit 1 rom the Action Statement. Maintenance personnel in conjung-l,l3l l tion with the API vendor representative perf ormed corrective maintenance using a reed l 1979. l l1 14 I l switch rejuvenator rendering the switch operable on July 1 80 7 8 9 OTHER ST ATUS E' SCO A DISCOVERY DESCRtPTION US  % POWER 1 s l F l@ l 0l 2l!@lNA l l A j@l Operator observation l A TiviTY CO TENT AVOUNT OF ACTIVITY LOCATION OF RELE ASE RELE ASE D OF PELE ASE A l l NA l 7

i 6 8 9 W @ l Zl@l IJ il 44 45 80 PERSONNEL E xPOSURES NUv8ER DESCRipTiCN -

Z NA LLL7J l 010 l 01@ TYPE @l PERSONNE L l'ou IES NUYBER OE SC A L P TION I

li is 8i 9101010 @l NA 7 11 12 g s

LOSS OF OR D AYAGE TO F ACILITY TvFE CESC09T1oN 7 9081407'f 7 ,

lil2j lZI@l NA

"

, 8 s m , m PUhllCITY

.

, I / NRC USE ON LY ,

KSLED '

i iii;iii,ii; j 12 I o l I N I@ l NADESCRIPTION 68 69 go ;

7 8 9 10 Richard W. Naylor 419-259-5000, Ext. 294 2 DVR 79-121 yayg gp ppgp373gg PHONE:

'

• TOLEDO EDISON COMPANY DAVIS-BESSE NUCLEAR POWER STATION U'RT ONE SUPPLEMENTAL INFORMATION FOR LER NP-33-79-100 DATE OF EVENT: July 12, 1979 FACILITY: Davis-Besse Unit 1 IDENTIFICATION OF OCCURRENCE: Faulty absolute position indication (API) reed switch for Rod 4 of Group 8 Conditions Prior to Occurrence: The unit was in Mode 1, with Power (>r,U) = 580, and Load (Gross MWE) = 200 Description of Occurrence: On July 12, 1979, at 0415 hours0.0048 days <br />0.115 hours <br />6.861772e-4 weeks <br />1.579075e-4 months <br /> while repositioning Group 8, Rod 4 of Group 8 absolute position indication (API) shifted from the 26% withdrawn to 0% actuating the asymmetric rod alarm. This placed the unit in the Action Statement of Technical Specification 3.1.3.3. The Technical Specifi-cation requires all abEolute position indication channels to be operable and capable of determining the rod group position within 6.5% when the unit is in Modes 1 and 2. As the rod withdrawal continued, the API indication returned to normal removing the unit from the Action Statement of Technical Specification 3.1.3.3.

Designation of Anparent Cause of Occurrence: The cause of this occurrence has been determined to be a component failure in the position indicator tube reed switch. An oxide film is believed to have built up on the reed switch contacts which interferes with the conduction across the switch contacts.

Analysis of Occurrence: There was no danger to the health and safety of the public or to station personnel. The relative position indication and the group position channels were operating and once the rod was withdrawn past the faulty reed switch, the API indication returned to cperabic status.

Corrective Action: Under Maintenance Work Order (MWO) 79-2499, aaintenance personnel with Diamond Power (the position indicator manufacturer) performed corrective mainten-ance on the reed switch with a position indicator reed switch rejuvenator. This in-strument places a higher than normal operation voltage across the reed switch while the rod is run past the switch causing the switch to actuate. The higher voltage removes the oxide film which returns the switch to operability. On July 13, 1979, the switch was retested Ed declared operable.

Failure Data: Although there have been numerous previously reported occurrences of API failures, only two have been identified as oxide buildup in reed switch contacts; see Licensee Event Reports NP-33-79-90 and NP-33-79-97.

LER #79-079 69 !l8