Information Notice 1989-61, Failure of Borg-Warner Gate Valves to Close Against Differential Pressure

Failure of Borg-Warner Gate Valves to Close Against Differential Pressure
	ML031180726
Person / Time
Site:	Beaver Valley, Millstone, Hatch, Monticello, Calvert Cliffs, Dresden, Davis Besse, Peach Bottom, Browns Ferry, Salem, Oconee, Mcguire, Nine Mile Point, Palisades, Palo Verde, Perry, Indian Point, Fermi, Kewaunee, Catawba, Harris, Wolf Creek, Saint Lucie, Point Beach, Oyster Creek, Watts Bar, Hope Creek, Grand Gulf, Cooper, Sequoyah, Byron, Pilgrim, Arkansas Nuclear, Braidwood, Susquehanna, Summer, Prairie Island, Columbia, Seabrook, Brunswick, Surry, Limerick, North Anna, Turkey Point, River Bend, Vermont Yankee, Crystal River, Haddam Neck, Ginna, Diablo Canyon, Callaway, Vogtle, Waterford, Duane Arnold, Farley, Robinson, Clinton, South Texas, San Onofre, Cook, Comanche Peak, Yankee Rowe, Maine Yankee, Quad Cities, Humboldt Bay, La Crosse, Big Rock Point, Rancho Seco, Zion, Midland, Bellefonte, Fort Calhoun, FitzPatrick, McGuire, LaSalle, 05000000, Zimmer, Fort Saint Vrain, Shoreham, Satsop, Trojan, Atlantic Nuclear Power Plant, Crane
Issue date:	08/30/1989
From:	Rossi C; Office of Nuclear Reactor Regulation
To:	;
References
	IN-89-061, NUDOCS 8908240164
	Download: ML031180726 (7)
	v • d • e

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UNITED STATES

NUCLEAR REGULATORY COMMISSION

OFFICE OF NUCLEAR REACTOR REGULATION

WASHINGTON, D.C.

20555

August 30, 1989

NRC INFORMATION NOTICE NO. 89-61:

FAILURE OF BORG-WARNER GATE VALVES TO

CLOSE AGAINST DIFFERENTIAL PRESSURE

Addressees

All holders of operating licenses or construction permits for nuclear power

reactors.

Purpose

This information notice is intended to alert addressees to potential problems

resulting from Borg-Warner gate valves with air or motor actuators failing to

close against differential pressures.

It is expected that recipients will

review the information for applicability to their facilities and consider

actions, as appropriate, to avoid similar problems.

However, suggestions

contained in this information notice do not constitute NRC requirements;

therefore, no specific action or written response is required.

Description of Circumstances

On March 14, 1988, a motor-driven auxiliary feedwater (AFW) pump discharge

isolation motor-operated valve (MOV) failed to fully close against a differen- tial pressure of 1800 psi at Catawba Nuclear Power Plant, Unit 2. The valve

failed while an AFW piping flush was being performed. At the time of the*

failure, the reactor was shut down and the steam generators were in hot standby.

The failure of the MOY to fully close was a contributing factor that led to

overfilling steam generator 2A and resulted in an automatic feedwater isola- tion.

The licensee, Duke Power Company, investigated the failure and reported

(Licensee Event Report No. 414/89-10) the cause to be a higher valve factor

than originally specified by the valve manufacturer, Borg-Warner, for sizing

valve actuators.

The valve factor is the term which is multiplied by the valve

seat area and the differential pressure across the valve to calculate one of

the parameters used in the standard valve thrust formula.

If a low valve

factor is used when sizing the valve air or motor actuator, the calculated

required valve thrust will also be low. This results in low torque switch

settings being specified and, in some cases, can result in undersized air or

motor actuators.

Discussion:

The AFW MOV that failed to close against 1800 psi, 2CA62A, was a Borg-Warner

4-inch, 1500-psi, flexible wedge, carbon steel gate valve with a pinned body

8908240164

IN 89-61 August 30, 1989 guide insert ring disk guide. Actuation of the torque switch stops the motor

when the valve is closed and fully seated. The torque switch was not bypassed

in the closing direction. Following the March 14, 1988, failure to close, the

valve was diagnostically tested and the switch settings were found to be within

specified tolerances.

Since no problems were found with the torque switch

settings, the valve was retested at 1800 psi differential pressure and again

failed to fully close.

In order to get the valve to fully close at 1800 psi

differential pressure, the closed torque switch setting had to be increased to

the maximum allowed by the manufacturer's design calculations. During the

subsequent refueling outage, the valve was disassembled and inspected by the

licensee in order to determine what was creating the excessive friction between

the disk and seat rings.

The inspection did not reveal any damage or condi- tions that would have caused excessive friction.

In November 1988, Duke Power Company performed differential pressure testing

on an MOV identical in design to 2CA62A.

This testing was performed on a test

loop at the Riverbend Steam Station. During the testing, valve signature

analysis was obtained. This testing resulted in higher than anticipated seating

loads at high differential pressure conditions, and the valve failed to close

on two of the tests completed with differential pressures greater than 1500

psi.

In November 1988, four Catawba Nuclear Power Plant Unit 1 AFW MOVs, identical in

design and size to 2CA62A, were differential pressure tested at l800 psi.ATll

four valves indicated intermediate position after being closed during the test

and were 1/8 inch to 1/2 inch from the fully closed position. The test results

identified that all four valves failed to wedge completely shut.

One valve did

not close enough to shut off flow.

In March 1989, valve 2CA62A and three identical Unit 2 AFW MOVs were differen- tial pressure tested at 1800 psi.

During the test, the three Unit 2 identical

valves'failed to completely close and isolate flow. All four valves failed to

wedge completely shut.

Valve signature analysis test data obtained during this

testing yielded closing valve factors ranging from 0.38 to 0.74 and were

different for each valve tested.

These were higher than the 0.3 valve factor

utilized by the valve manufacturer to size the actuators.

Testing performed by Duke Power Company on carbon steel valves similar in

design to 2CA62A has yielded opening valve factors ranging from 0.48 to 0.67.

Testing performed by Duke Power Company on stainless steel valves similar to

2CA62A has yielded valve factors ranging from slightly higher than 0.3 to 0.5.

Based on Duke Power Company testing, the valve factor of 0.3 originally uti- lized for Borg-Warner flexible wedge carbon steel or stainless steel gate

valves with pinned body guide insert rings when sizing air or motor actuators

was not correct.

The actual valve factors, as measured by Duke Power Company, vary from valve to valve but are consistently above 0.3.

This results in the

potential that air- or motor-actuated valves will not operate against a differ- ential pressure when called upon to do so because of inadequate torque switch

settings or undersized actuators.

IN 89-61 August 30, 1989 Related Generic Communications:

The general concern of the ability of motor-operated valves to function properly

when subjected to the design basis loadings has been previously addressed in

NRC Bulletins 81-02, "Failure of Gate Type Valves to Close Against Differential

Pressure," and 85-03, "Motor-Operated Valve Common Mode Failures During Plant

Transients Due to Improper Switch Settings;" Circular 77-01, "Malfunctions of

Limitorque Valve Operators;" Information Notices 81-31, "Failure of Safety In- jection Valves to Operate Against Differential Pressure," and 85-50, "Complete

Loss of Main and Auxiliary Feedwater at a PWR Designed by Babcock & Wilcox;"

and Generic Letter 89-10, "Safety-Related Motor-Operated Valve Testing and

Surveillance."

This information notice requires no specific action or written response.

If

you have any questions about the information in this notice, please contact the

technical contact listed below or the appropriate NRR project manager.

Charles E. Rossi, Director

Division of Operational Events Assessment

Office of Nuclear Reactor Regulation

Technical Contact:

S. Tingen, RII

(404) 331-2603 Attachment:

List of Recently Issued NRC Information Notices

Attachment

IN 89-61

August 30, 1989

Page I of I

LIST OF RECENTLY ISSUED

NRC INFORMATION NOTICES

Information

Date of

Notice No.

Subject

Issuance

Issued to

88-48, Supp. 2

89-60

89-59

89-58 Licensee Report of Defective

8/22/89

Refurbished Valves

Maintenance of Teletherapy

8/18/89 Units

Suppliers of Potentially

8/16/89

Misrepresented Fasteners

Disablement of Turbine-Driven 8/3/89

Auxiliary Feedwater Pump Due

to Closure of One of the

Parallel Steam Supply Valves

All holders of OLs

or CPs for nuclear

power reactors.

All NRC Medical.

Teletherapy Licensees.

All holders of OLs

or CPs for nuclear

power reactors.

All holders of OLs

or CPs for PURs.

89-57 Unqualified Electrical

7/26/89

All holders of OLs

Splices in Vendor-Supplied

or CPs for nuclear

Environmentally Qualified

power reactors.

Equipment

89-56 Questionable Certification

7/20/89

All holders of OLs

of Material Supplied to the

or CPs for nuclear

Defense Department by Nuclear

power reactors

Suppliers

89-45, Metalclad, Low-Voltage

7/6/89

All holders of OLs

Supp. I

Power Circuit Breakers

or CPs for nuclear

Refurbished With Substandard

power reactors.

Parts

89-5S

Degradation of Containment

6/30/89

All holders of OLs

Isolation Capability by a

or CPs for nuclear

High-Energy Line Break

power reactors.

89-54 Potential Overpressurization

6/23/89

All holders of OLs

-of the C~~.~4eowo-Hng---

-

ii-o CF~, Fr rueltr

=

Water System

power reactors.

89-53 Rupture of Extraction

6/13/89

All holders of OLs

Steam Line on High

or CPs for nuclear

Pressure Turbine

power reactors.

OL

Operating License

CP

Construction Permit

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NUCLEAR REGULATORY COMMISSION

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