ML19291C450

LER 79-041/03L-0:on 791217,while Testing Purge Isolation Valve,Drywell Purge Valve AO-1-1601-21 Exceeded Max Close Time.Caused by Speed Control Being Out of Adjustment.Speed Control Adjusted

ML19291C450
Person / Time
Site:	Quad Cities
Issue date:	01/15/1980
From:	Dunesia Clark COMMONWEALTH EDISON CO.
To:	NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION III)
Shared Package
ML19291C445	List: ML19291C444 ML19291C450
References
LER-79-041-03L-04, LER-79-41-3L-4, NUDOCS 8001240445
Download: ML19291C450 (2)

Text

NRC FORM 366 U. S. NUCLEAR REGULATORY COMMISSION (7 771 *

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7 8 60 61 DOCKET NUMBER 6d EVENT DATE EVENT DESCRIPTION AND PROBABLE CONSEQUENCES h O 2 l While testing the operability and closure times of the Unit One primary containment l o 3 l purge isolation valves, drywell nitrogen purge valve, A0-1-1601-21 was timed to closel o 4 l in 11.25 seconds. This time exceeded the maximum closure time of 10 seconds that is l O s I required in Technical Specification Table 3.7-1. The two outboard isolation valves l

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41 42 43 44 47 CAUSE DESCRIPTION AND CORRECTIVE ACTIONS i O i The speed control on the valve was out-of-adiustment. The valve soeed control was I li li l adjusted and the valve was cycled three times and had a closure time of 7.25 l ii 12] l seconds. l i 3 I l i 4 I I

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1. LER NUMBER: LER/R0 79-41/03L-0

11. LICENSEE NAME: Commonwealth Edison Company Quad-Cities Nuclear Power Station Ill. FACILITY NAME: Unit One.

IV. DOCKET NUMBER: 050-254 V. EVENT DESCRIPTION:

On December 17, 1979, while testing the operability and closure times of the Unit One primary containment purge isolation valves, the drywell nitrogen purge valve, A0-1-1601-21, closed in 11.25 seconds. This time exceeded the maximum closure time of 10 seconds that is required in Technical Specification Table 3 7-1. The valve was being tested due to a modification performed on the valve operator which restricted its open stroke to 40 degrees (90 degrees being full open). This modification was being installed as per a NRC requirement committment. A work request was written to adjust the valve closure time. Unit One was shutdown for maintenance at the time of this occurrence. The last time this valve failed the closure timing test was January 25, 1979 and was reported in .

LER/R0 79-06/79 All other valves that were modified were timed to close within Technical Specification limits.

VI. PROBABLE CONSEQUENCES OF THE OCCURRENCE:

The probable consequences of this occurrence were minimal.

The A0 1-1601-21 valve is the inboard drywell primary containment isolation valve in the nitrogen purge sytem. The two outboard isolation valves in the system were operable at all times and would have automatically closed as required to isolate the primary containment from the environs. Since the ability to isolate the primary containment during a Group 11 isolation remained, safe operation of the reactor was not af fected as a result of this occurrence.

Vll. CAUSE:

The cause of this occurrence is attributed to the speed control valve on the instrument air supply to the valve operator being out-of-adjustment. The problem possibly occurred while work was being performed to modify the purge valve to limit travel of the valve to 40 degrees. The area of the purge valve is

, very confined; thus the speed control valve could have been bumped out of adjustment. The speed control is part of a 4-way soienoid-operated Versa valve, model VGS-4422-U.

Vill. CORRECTIVE ACTION:

The speed control valve which supplies air to the valve operator was adjusted. On December 17, 1979 the valve was cycled three times and had a closure time of 7.25 seconds.

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