ML20151H426

Responds to Request for Addl Info Re IE Bulletin 85-003. Motor-Operated Valve Common Mode Failures During Plant Transients Due to Improper Switch Settings

ML20151H426
Person / Time
Site:	Trojan File:Portland General Electric icon.png
Issue date:	04/08/1988
From:	Cockfield D PORTLAND GENERAL ELECTRIC CO.
To:	Martin J NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION V)
References
IEB-85-003, IEB-85-3, NUDOCS 8804200384
Download: ML20151H426 (4)

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David W. Cockfield Vice President. Nuclear April 8, 1988 Trojan Nuclear Plant Docket 50-344 License NPF-1 Mr. John B. Martin Regional Administrator, Region V U.S. Nuclear Regulatory Commission Creekside Oaks Office Park 1450 Maria Lant, Suite 210 Walnut Creek CA 94596-5368

Dear Mr. Martin:

l Response to Request for Additional Information Concerning l Inspecticn and Enforcement (IE) Bulletin 85-03, Motor-operated Valve

' Comon Mode Failures Durinr, Plant Transie..v 1 Due to Improper Switch Setting,e l

By letter dated March 9, 1988, the Nuclear Regulatory Commission transmitted a l request for additional information regarding Portland Concral Electric's response to IE Bulletin 85-03. Attachment A provides our response to each of the three items included in your letter, and supplements our previous submittals ca*cd July 15, 1986 and December 15, 1987, which detailed our program for compliance wi' n the require-ments of the Bulletin.

Sincerely, Attaciunent c: U.S. Nuclear Regulatory Commission ATTN: Document Control Desk Mr. William Dixon State of Oregon Department of Energy 1

Mr. R. C. Barr NRC Resident Inspector Trojan Nucioar Plant Subscribed and sworn to before me this 8th day of April ,1988. ~

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i Trojan Nuclear Plant Mr. John B. Martin Docket 50-344 Areil 8, 1988 License NPF-1 Attachment A Page 1 of 3 RESPONSES TO REQUEST FOR ADDITIONAL INFORMATION REGARD'.NG INSPECTION AND ENFORCEMENT (IE) BULLETIN 85-03, MOTod-OPERATED VALVE COMMON MODE FAILURES DURING PLANT TRANSIENTS DUE TO IMPROPER SWITCH SETTINGS

1. Item 1 Has water hammer due to valve closure been considered in the determination of differential pressures? If not, explain.

Portland General Electric (PGE) Response Water hammer due to valve closure was noi considered due to the following:

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a. Water hammer is a shock wave resulting from rapid or instantaneous changes in fluid velocity. Water hammer can contribute to the differential pressure of rapidly closing valves. A gradual change of fluid velocity does not produce water hammer effects. The rate of closure of all valvos in our submittal is not fast enough to produce water hammer, t

b.

The dif ferential pressures listed l i our suh ..tal are very conservative and would envelop any .xpected transients.

2. Item 2 If MOVATS is planned for application to some MOVs which are not included in its data base, commit to and describe an alternate method of determining the extra thrust necessary to overcome pressure differentials for these valves.

PGE Response We are using Motor-Operated Valve Analysis and Testing System (MOVATS) test equipment , but are not using MOVATS thrust values, for 10 valves outside of MOVATS present data base.

Eight of these valves. Control Valve (CV) 3004A1 through CV 300AD2, are the auxiliary feedwater control valves. These are balanced-type l control valves which require very low thrust to open and close. The torque switch settings for the motor operators for these eight valves were set at values corresponding to over three times the manu-f acturer's required thrust at the rated dif ferential pressure but still below the manufacturer's allowable limit. Because these are centrol valves, we hevo a high degree of confidence that the manu-facturer's thrust values are accurate. We will continue to keep these i' .-_.

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Trojan Nuclear Plant Mr. John B. Martin Docket 50-344 April 8, 1988 License NPF-1 Attachment A Pago 2 of 3 I

1 valves set at three times the manufacturer's required thrust or higher with two times as the minimum setting.

! One valve, Motor-Operated (MO) 3060B, which provides service water for auxiliary feedwater equipment cooling, is a 6-inch butterfly valve with a centerline disc. The highest thrust requirements are not caused by valve differential pressure but are due to unseating and seating the valve against the seat. During the 1987 outage testing, equipment to fully test 90-degree valves, such as butterfly valves, was not available from MOVATS. We did, however, observe that the seating and unseating forces of this valve did not exceed the torque switch spring pack preload. Since the preload is a fraction of the actual corque switch setting, we feel there is adequate margin at the valve's present sotting to ensure operability. We will maintain the present torque switch settings.

One valve, MO 3071, is the auxiliary feedwater pump turbine trip and throttle valve. This valve is a specific type of cor. trol and trip valve outside of MOVATS data base. It utilizes a pilot to reduce opening thrust and system pressure to assist closing. We have set this valve over 30 percent above the manufacturer's required opening and closing thrust to ensure valve operability. We will continue to maintain this margin.

3. Item 3 The proposed program for Action Items b, c, and d of the Bulletin is incomplete. Provide the following details ar a minimum:

a. Commitment to a training program for setting switches, maintaining valve operators, using signature testing equipment and interpret-ing signatures,

b. Commitment to justify continued operation of a valve determined to

be inoperable.

PCE Response

a. The current training program includes appropriate training for switch setting and valve operator maintenance. Recently, all Plant electricians have completed training on signature testing and basic signature interpretation. This training will be incorporated into a formal training module by December 31, 1988.

Additional signature analysis training for selected personnel is also planned and will be completed by December 31, 1988.

b. Valve operability decisions are based on the Technical Specifica-tion Limiting Conditions for Operation. In making an operability

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' Trojan Nuclear Plant Mr. John B. Martin Docket 50-344 April 8, 1988 Licenso NPF-1 Attachment A Page 5 of 3 l

decision, wa assess whether or not t'.ie component is capable of performing its design function. If it cannot meet this criteria, the component or system is declared to be inoperable, and we comply with the appropriate action statement. If an unusual circumstance were to arise where we cannot comply with the action statement, we will follow the direction of the Technical Specifi-cations for conditions in excess of the Limiting Condition for Operation requirements.

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