ML20009B552

LER 81-004/01T-0:on 810529,during Maint Shutdown,Msiv 2CV-2017 Failed to Shut.Caused by Two Vent Valves for Air Operator Failing to Open.Valves Replaced

ML20009B552
Person / Time
Site:	Point Beach
Issue date:	06/12/1981
From:	Fay C WISCONSIN ELECTRIC POWER CO.
To:	NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION III)
Shared Package
ML20009B549	List: ML20009B548 ML20009B552
References
LER-81-004-01T, LER-81-4-1T, NUDOCS 8107160282
Download: ML20009B552 (3)

Text

NRC F ORJJ 366 ' U. S. NOC1.E AR RE!OL ATCGY COMMISSION (77/l

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? ET NUMBER EVENT DATE EVENT DESCRIPTION AND PROBABLE CONSEQUENCES h 10 l 2 l l At 0256 on May 29, 1981, during a routine shutdown for secondary plant l 0 3 l maintenance, MSIV 2CV-2017 failed to shut as required. Imme diate j O 4 I investigation revealed the two vent valves for the air operator failed l l O l s i l to open, preventing the closure of 2CV-2017. Vent valve 2SV-2017C was l O s l manually tripped open and the MSIV shut irunediately. This event is j O 7 l reportable under Technical Specifi cation 15.6.9. 2. A.5. This event is l l 0 ;e j l similar to LER 77-02 Docket No. 50-301. l 7 8 9 80 DE CODE SU8C E COMPONENT CODE r.SCODE S E 7

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ATTACHMENT TO LICENSEE EVENT REPORT NO. 81-004/0lT-0 Wisconsin Electric Power Conpany Point Beach Nuclear Plant Unit 2 Docket No. 50-301 At 0256 hours0.00296 days <br />0.0711 hours <br />4.232804e-4 weeks <br />9.7408e-5 months <br /> on May 29, 1981, with the unit in the off-line, zero power, critical condition in preparation for operator licensing startups and secondary plant maintenance ,

the operator attempted to shut both main steam isolation valves with a remote manual signal in preparation to take steam out. Main steam isolation valve 2CV-2018 shut as called for; main steam isolation valve 2CV-2017 failad to shut. This is a reportable occurrence in accordance with Technical Specification 15.6.9.2. A.5 with 24-hour written notification provided to U. S. NRC Region III on May 29, 1981.

An immediate investigation ensued and found the two air-operated vent solenoid-operated valves, 2SV-2017C&D, were shut preventing closure of 2CV-20l*/. The two air-operator supply solenoid valves, 2SV-2017A&B, were shut as required.

Vent valve 2SV-2017C was locally manually tripped at the valve operator station and the main steam isolation valve, 2CV-2Ll7, shut immediatel".

The air operator of the main steam isolation valve has a two-train logic. There are two in-series air supply solenoids. The vent path has two parallel solenoid valves.

The supply line is orificed so that on failure of both supply solenoids to close, a ven'c will still cause closure of the main steam isolation valve. Two manual key-operated isolation valves are provided on the vent lines upstream of the air vent solenoid-operated valves to allow for testing. Due to l

reliability problems experienced in the past with the original l installed Lawrence Series 1200 internal pilot-operated sole-noid valve, they were replaced on one main steam isolation valve operator assembly with ASCO Bulletin 8015 internal pilot-cperated solenoid valves. Prior to the initial installation of the new ASCO valves, a testing program was undertaken which included vibration, leakage , voltage and operational testing.

At the conclusion of these tests the ASCO valve was dis-assambled and inspected. At the conclusion of this program the ASCO valves were approved for installation.

The new ASCO valves were installed during the recent refueling outage and were extensively tested in place l prior to the successful completion on May 22, 19 81, o f the tined test required by Technical Specification 15.4.7. After the failure of these valves to operate on 1:ay 29, 1981,

attempts were made to duplicate this failure mode but all the valves operated properly. Upon the completion of the i other secondary plant maintenance and training startupg the main stcam isolation valve 2CV-2017 was tested at 2000 hcurs on May 31, 1981. Although 2CV-2017D (" green" train vent valve) operated sluggishly, the main steam isolation valve cycled properly on each of six attempts. Due to this sluggish operation, both vent valves, 2CV-2017C&D, were replaced on June 1,1981, and proper operation was again verified. The removed valves are undergoing a testing and evaluation program to attempt to de termine the cause of their f ailure. In addition, the testing frequency has been increased on the 2CV-2017 operator to foretell future problems.

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