ML20003C390

AO 50-219/74/21:on 740313,bypass Valve RE22D Opened,Causing Main Steam High Flow Sensor RE22D to Be Inoperable.Caused by Incorrect Valve Positioning.Instrument Technicians to Be Advised Re Critical Importance of Valve Lineup Checks

ML20003C390
Person / Time
Site:	Oyster Creek
Issue date:	03/22/1974
From:	JERSEY CENTRAL POWER & LIGHT CO.
To:
References
AO-50-219-74-21, NUDOCS 8103030305
Download: ML20003C390 (3)

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OYSTER CREEK NUCLEAR GENERATING STATION FORKED RIVER, NEW JERSEY 08731 Abnormal Occurrence Report No. 50-219/74/21 Report Date March 22,1974

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Occurrence Date

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March 13,1974 J.

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L Identification of Occurrence

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Violation of the Technical Specifications, Table 3.1.1.B.2, which specifies that the RE22 main steam line high flow sensors actuate at a differential pressure corresponding to a line flow of <120% of rates steam flow (97.5 psid).

This event is considered to be an abnormal occurrence as defined in the Technical Specifications, paragraph 1.15B.

Conditions Prior to Occurrence The plant was operating at steady-state power.

He major plant parameters at the time of the event were as follows:

Power:

Core, 1750 MWt Electric, 595 MWe 5

Flow:

Recirculation,15.1 x 10 epm 6

Feedwater, 6.46 x 10 lb/hr Stack Gas: 27,000 pCi/sec Description of Occurrence At 0040 on March 13, 1974, while taking daily Technical Specification log read-ings, an operatcr noted and reported to the shift foreman that the differential pressure indicator for Sensor RE22D indicated 0 psid and that the instrument lines were hot. The operator found the RE22D bypass valve to be open, causing Sensor RE22D to be inoperable.

Upon closing the bypass valve, the RE22D differ-ential pressure indication returned to normal.

Apparent Cause of Occurrence he apparent cause of this incident was incorrect valve positioning.

Investi-gation has not established the exact time or the individual (s) involved in the opening of the RE22D bypass.

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Abnormal Occurrence No. 50-219/74/21 Page 2 He valve lineup of the steam flow sensors was checked by an instrument technician and then independently rechecked by another instrument technician at approxi-mately 1000 on March 11, 1974. He RE22D bypass was found to be closed at this time.

Plant startup commenced subsequent to these checks and criticality was achieved at 1614 on March 11, 1974.

It has been concluded that the incorrect positioning of the RE22D bypass valve took place sometime between the completion of the valve lineup checks on March 11, 1974 and discovery of the incorrect valve position at 0040 on March 13, 1974.

Analysis of Occurrence The original report of this incident (March 13, 1974) stated that the safety significance of this occurrence was minimal since seven of the eight RE22 sensors remained operable during the period when the RE22D bypass was open. At that time, it had not been noted that the RE22D bypass could have bypassed the differential pressure signal to RE22A, B, and C and the No.1 steam line steam flow sensor had the bypass flow path been less restrictive. The fact that the RE22A, B, and C and the No.1 steam line flow sensor remained operable and accurate is demonstrated by log readings and the steam flow recorder graph. He operator who discovered the "0" differential pressure indication of RE22D re-corded the readings of all eight sensors as found while the RE22D was open.

He indications of RE22A, B, and C were comparable to those of the unaffected sensors, RE22E, F, G, and H.

A check of the steam flow recorder graph shows no increase in indicated steam flow as would be expected had the differential pressure applied at the steam flow sensor undergone an increase when the RE22D bypass valve was shut.

It is noted here that this discrepancy was identified during the taking of Technical Specification log readings. This not only demonstrates the useful-ness of this data taking, but also indicates that the operator taking these readings was alert and properly responded to an abnormal indication.

Corrective Action Instrument technicians will be advised via a memorandum of the details of this event, the critical importance of valve lineup checks on systems associated with reactor protection, and the importance of immediately reporting instances in which valves are found to be incorrectly positioned.

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