ML19351G408

LER 80-090/03L-1:on 801205,setpoints for Borated Water Storage Tank Low Level Bistable BA312 & Containment Pressure Bistable BA309 Found Out of Tolerance.Caused by Component Failure.Bistables Recalibr

ML19351G408
Person / Time
Site:	Davis Besse
Issue date:	01/02/1981
From:	Isley T TOLEDO EDISON CO.
To:	NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION III)
Shared Package
ML19351G397	List: ML19351G396 ML19351G408
References
LER-80-090-03L, LER-80-90-3L, TAC-43253, NUDOCS 8102230647
Download: ML19351G408 (4)

Text

NRC FORM 366 ,

U. S. NUCLE AR REGULATORY COMidlSSION 87-7 7) ,

LICENSEE EVENT REPORT (PLEASE PRINT OR TYPE ALL R50UIRED INFORMA' /t)

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$R$ lL 60 l@l 0l 5 lDOCKET 61 0] -l NLVBER 0 l 3l 4 l 686 l@l1 63 l2 EVENT (0DATE l5 l8 l0 l@l 0lREPORT 74 75 Il 0lDATE 2] 8l 1l@ 83 EVENT DESCRIPTION AND PROBABLE CONSEQUENCES h o 2 l (NP-33-80-115) On 12/5/80 at 1730 hot:rs during surveillance testing, the setpoint forl Io lal  ! the Borated Water Storage Tank low level bistable BA312 was found out of tolerance. l l0 l4 l l On 12/6/80 at 0750 hours0.00868 days <br />0.208 hours <br />0.00124 weeks <br />2.85375e-4 months <br /> during testing, the setpoint for the containment pressure I l o I s l l bistable BA309 was also found out of tolerance. Both occurrences placed the unit in l Io is ] l Action Statement 9 of Technical Specification 3.3.2.1. There was no danner to the l l o l 7 l l health and safety of the public or station personnel. The remaining three Safetv l I

I o 18 I l Features Actuation System channels were operable.

SYSTEM CAUSE CAUSE COUP. VALVE CODE CODE SUBCODE COMPONENT CODE SU8 CODE SUBJoOE lol9! lI lB l@ Wh Wh lIl Nl S l T l R l U l@ lS l@ y h 12 13 18 19 20 7 8 9 to 11 REVISION SEQUENTIAL OCCUR R E NCE REPORT REPORT NO. CoOE TYPE NO.

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42 43 44 47 CAUSE DESCRIPTION AND CORRECTIVE ACTIONS h li l o l ] The cause of these occurrences can be attributed to a component failure. The bistahic);

I i 11 I l are subject to instrument drif t. Upon finding BA312 and BA309 out of calibration. 1 I

[TJ q l they were immediately recalibrated as per the test (ST 5031.01) procedure to within i

i l l3l3)l the technical specification limit. The voltage between common and ground will be 1

I I Ii 14 I l checked on a monthly basis to ensure an AC voltage does not go undetected. 80

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'*'isS S1 sPOwER OTHER STATUS ISC RY DISCOVERY DESCRIPTION l

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l M*R 80-205 & y)flE OF PREPAHER PHONE:

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TOLEDO EDISON COMPANY I5 AVIS-BESSE NUCLEAR POWER STATION UNIT ONE SUPPLEMENTAL INFORMATION FOR LER NP-33-80-115 DATE OF EVENT: December 5, 1980 FACILITY: Davis-Besse Unit 1 IDENTIFICATION OF OCCURRENCE: Safety Features Actuation System (SFAS) Bistables

,l Out of the Technical Specification Allowable Value Conditions Prior to Occurrence: The unit was in Mode 3 with Power (MRT) = 0 and Load (Gross MUE) = 0.

, Description of Occurrence: On December 5, 1980 at 1730 hours0.02 days <br />0.481 hours <br />0.00286 weeks <br />6.58265e-4 months <br /> during the performance of the SFAS Monthly Test, ST 5031.01 on SFAS Channel 3, the setpoint for the Borated Water Storage Tank (BUST) low level bistable (BA 312) was found to be out of toler-ance. The bistable as found value was 0.552 V and the allowable value is less than or equal to 0.551 V.

On December 6, 1980 at 0750 hours0.00868 days <br />0.208 hours <br />0.00124 weeks <br />2.85375e-4 months <br />, ST 5031.01 was performed on SFAS Channel 3 to verify operability after troubleshooting to find the cause of the 120 VAC potential between power supply common and ground (see Licensee Event Report NP-33-80-113). Thel containment pressure 38.4 psia bistable (BA 309) was found out of tolerance. The i

bistable as found value was 1.428 V and the allowable value is less than or equal to 1.427 V.

See attached tables for additional information.

Both occurrences placed the unit in Action Statement 9 of Technical Specification 3.3.2.1. The action statement requires the inoperable channel to be placed in the tripped condition within one hour. Both bistables were immediately recalibrated per tbe test procedure (ST 5031.01), removing the station from the action statement.

Designation of Apparent Cause of Occurrence: The cause of these-occurrences can be y attributed to a component failure. The bistables are subject to instrument drift.

The instrument drift was probably aggravated by the 120 VAC problem on the cabinet Common. .

I Analysis of Occurrence: There was no danger to the health and safety of the public or to station personnel. The remaining three SEAS Channels were operable and capable

, of performing their designed function.

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Corrective Action: Upor finding the BWST level bistable BA 312 and'the containment pressure bistable BA 309 out of calibration they were immediately recalibrated as per the test (ST 5030.01) procedure to within the Technical Specification limits.

To be sure that an AC voltage on common does not exist for an extended period of time 3

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the voltage between common'and. ground will be checked on a monthly basis per i- ST 5031.01, SFAS Monthly Test.

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LER #80-090

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TOLEDO EDISON COMPANY DAVIS-BESSE NUCLEAR POWER STATION UNIT ONE SUPPLEMENTAL INFORMATION FOR LER NP-33-80-115 PAGE 2 Failure Data: There have been three previous similar occurrences of bistable drift, l see Licensee Event Reports NP-33-78-84 (78-070), HP-33-78-140 (78-119) and NP-33-79-50 (79-045).

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LER #S0-090

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TOLEDO EDISON COMPANY DAVIS-BESSE NUCLEAR POWER STATION UNIT ONE SUPPLEMENTAL INFORMATION FOR LER NP-33-80-115 PAGE 3 CONTAINMENT PRESSURE BA 309 (After 120 VAC Removed)

Pressure (psia) Volts (1)

Full Range 60 2.00 As Found 38.55 1.428 9 9 2 A 1.875 in. o7.5 in.

Allowable Value (TS) - 38.52 1.427 (O.3125%) (1.25%)

Y 38.4 1.425 V Trip Setpoint Trip Setpoint y_.37.65 1.404 v Zero O C.4 Worst case drift 1.5%

(1) V=psiax1.6)+0.4 60 /

1 BWST LEVEL (BA 312) (With 120 VAC on Common)

Level (inches) Volts (1)

Full Range 600 2.00 As Found 57 0.552 9 ,

d 0.15 psi i Allowable Value (TS) /_56.7 0.551 (0.25%) d 0.9 psi (1.5%)

Trip Setpoint {-55.0 0.547  % /

1 Trip Setpoint .Z.49.5 0.532 di Allowable Value (TS) Z 48.3 0.529

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Zero 0 0.4 Worst case drift 1.25% of full scale (1) V= level (in) x 1.6 + 0.4 600 .

LER #80-090 ,