05000265/LER-1978-032-03, /03L-0 on 780929:Unit 2 Main Steam Target Rock Pressure Relief Valve 2-203-3A Failed to Open While Performing Test.Caused by Broken Air Line to Valves Manual Air Operator

/03L-0 on 780929:Unit 2 Main Steam Target Rock Pressure Relief Valve 2-203-3A Failed to Open While Performing Test.Caused by Broken Air Line to Valves Manual Air Operator

ML20027A396
Person / Time
Site:	Quad Cities
Issue date:	10/20/1978
From:	Reed M COMMONWEALTH EDISON CO.
To:
Shared Package
ML20027A395	List: 05000265/LER-1978-032, Forwards LER 78-032/03L-0 05000265/LER-1978-032-03, /03L-0 on 780929:Unit 2 Main Steam Target Rock Pressure Relief Valve 2-203-3A Failed to Open While Performing Test.Caused by Broken Air Line to Valves Manual Air Operator
References
LER-78-032-03L-01, LER-78-32-3L-1, NUDOCS 7811240224
Download: ML20027A396 (3)

LER-1978-032, /03L-0 on 780929:Unit 2 Main Steam Target Rock Pressure Relief Valve 2-203-3A Failed to Open While Performing Test.Caused by Broken Air Line to Valves Manual Air Operator

Event date:
Report date:
2651978032R03 - NRC Website

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60 61 DOCKET NUMBE R 68 69 EVENT DATE 74 76 REPORT DAT E 80 EVENT DE:,CRIPTION AND PROB ABLE CONSEQUENCES h l The Unit Two Main Steam Target Rock Pressure Relief Valve (2-203-3A) failed to open l

o 2 [while performing semi-annual test procedure QOS 201-1.

Unit Two was being shutdown l

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CAUSE DESCRIPTION AND CORRECTIVE ACTIONS h A

IThe cause of this occurrence was due to a broken air line to the valve's manual air l

i O i i l operator. The corrective action taken was to repair the broken air line. The L ! 2-203-3A valve wa's subsequently tested during unit startup and proven operable.

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LER NUMBER:

LER/R0 78-32/03L-0 ll.

LICENSE NAME:

Commonwealth Edison Company Quad-Cities Nuclear Power Station Ill.

FA_CILITY NAME: Unit Two IV.

DOCKET NUMBER: 050-265 V.

EVENT DESCRIPTION

On September 29, 1978, Unit Two Main Steam Target Rock Pressure Relief Valve (2-203-3A) failed to open while performing semi-annual test procedure QOS 201-1.

When the unit operator placed the key switch to the MANUAL position, he received a dual Indication on the valve position Indicating Ilghts, and

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observed only a 5* compensating closure of the full open Main Steam B/ pass Valve. The operator again atten.pted to open the relief valve, but no change in bypass valve position was observed.

Unit Two was in the RUN mode at a thermal power of 570 MWt.

The Unit was being shutdown for a scheduled weekend maintenance outage.

VI.

PROBABLE CONSEQUENCES OF THE OCCURRENCE:

The consequences of this occurrence were minimal since redun-dancy has been provided in the automatic pressure reIIef function, in that only four of the five relief valves are I

required to operate. All four Electromatic Relief Valves were tested and found to be operable. Thus, loss of one of the i.

relief valves does not materially affect the pressure relieving capability of the automatic pressure relief system. Also, the g

four Electromatic Relief Valves were capable of actuating in F-the event of an ECCS auto blowdown initiation. The safety mode of the 2-203-3A Target Rock Valve was unaffected and would have opened at designed pressure conditions.

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CAUSE

The 2-203-3A relief valve failed to open due to a broken stainless steel air line to the diaphragm of the valve operator.

The air line was found broken at the valve.

The 2-203-3A safety relief valve, Model 67F, is manufactured by Target Rock Corporation.

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CORRECTIVE ACTION

Work Request number 4529-78 was written to repair the broken air line. The end of the air line was rethreaded and reattached to the valve.

On October 1, 1978, while Unit Two was returning to power, the 2-203-3A relief valve was again tested and pioven to operate properly.

Since this is the first failure of this type, no further actions are deemed necessary.

9