ML19261A806

LER 78-032/03L-0 on 781218:calibr & Functional Test for Drywell Pressure Instruments PS1-1001-89 a Thru D Found Not in Accordance W/Tech Specs.Caused by Instrument Drift

ML19261A806
Person / Time
Site:	Quad Cities
Issue date:	01/15/1979
From:	Tietz G COMMONWEALTH EDISON CO.
To:	NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION III)
Shared Package
ML19261A799	List: ML19261A797 ML19261A806
References
LER-78-032-03L, LER-78-32-3L, NUDOCS 7902080190
Download: ML19261A806 (2)

Text

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/ 8 00 61 C %<ET*.UYeEH EVENT DESCalPTION AND PRO 9 ABLE CONSEQUENCES h o 2 l The calibration and functional test surveillance f requency for testing the HPCI initiatibn~

[ o 131 i switches associated with drywell pressure inst ruments P S 1-1001-89A thru D was found I o a lnot to be in accordance with Technical Specification Table 4.2-1. Uoon calibratinn rhn l lO ls] l D switch tripped at 2.02 psig which is in excess of the < 2.00 psig limit established _

l Redundant switches were found to be within limits, thus HPCI 0 c l in Table 3.2-2 l g initiation was not jeopardized by this event. l 0lB 63 7 8 9 SYSTEM CAUSE CAUSE COMP. VALVE CODE CODE SUBCODE COMPONENT CODE SUBCODE SUBCODE O 9 ll lB l@ [ Dl@ l Z l@ l ll Hl Sl Tl Rl Ul@ Sj@ J@ 20 7 8 9 10 11 12 13 18 19 SE QUE NTI AL OCCURRENCE REPOHT REVISION EVENT YEAR REPORT NO. CODE TYPE NO.

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CAUSE DESCRIPTION AND CORRECTIVE ACTIONS h i O l Procedural inadec;uacy-The HPCI switches were inadvertently excluded from the monthlv l i i j ECCS test program. These switches have been functionally tested once each ooerating I

,, ,7y; cycle. The D switch tripped at 2.02 psig due to instrument drif t. This switch was I

,9,j g re-calibrated. Temporary testing procedures have been written and permanent revisions g gare being processed.

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1. LER NUMBER: LER/R0 78-32/03L-0

11. LICENSEE NAME: Commonwealth Edison Company Quad-Ci ties Nuclear Power Station Ill. FACILITY NAME: Unit One IV. DOCKET NUMBER: 050-254 V. EVENT DESCRIPTION:

On December 18, 1978 it was noticed that the two switches of PS l-1001-89A thru D were tested at different intervals. These switches sense high drywell pressure and trip at < 2.0 psig. Switch number 1 in conjunction with a low-low reactor water level signal will start the 120 second timer to initiate the Auto Blowdown System. This switch has been functionally tested each month in accordance with Technical Specification Table 4.2-1. Switch number 2, which initiates HPCI, has been functionally tested each operating cycle during refuel outages. Upon discovery of the problem, a temporary procedure was written to calibrate and perform a functional check on the switches. It was discovered that PS l-1001-89D tripped at 2.02 psig, which is in excess of Technical Specification Table 3 2-2. The other three switches were within the proper limits. The switch was recalibrated and tested satisfactory.

VI. PROBABLE CONSEQUENCES OF THE OCCURRENCE:

The safety implication of this occurrence are minimal due to the fact HPCI would have initiated as intended had a high drywell condition occurred. The fact that one of the switches tripped above the setpoint did not jeopardize HPCI initiation because the PS-1001-89 A and C switches would have tripped the necessary relay logic to start HPCI. The number 2 switch of PS l-1001-89A/B/C/D had been functionally tested each operating cycle with no previous failures since installation.

Vll. CAUSE:

The primary cause of this occurrence is attributed to procedure inadequacy.

Pressure switches 1-1001-89A thru D have two separate internal switches, and the HPCI initiation switch was inadvertantly excluded from the ECCS instrumentation test program.

The cause of PS l-1001-89D tripping at 2.02 psig is attributed to instrument set point drift.

Vill. CORRECTIVE ACTION:

The immediate corrective action was to write a temporary procedure, number 1155, to functionally test and calibrate the pressure switches while the unit was in operation. When the 89D switch tripped in excess of 2.0 psig it was recalibrated and successfully tested. The temporary procedure will be implemented as a permanent procedure. The pressure switches were manufactured by Static-0-Ring, model number 12N-AAS-PP.