Information Notice 1994-69, Potential Inadequacies in the Prediction of Torque Requirements for and Torque Output of Motor-Operated Butterfly Valves

Potential Inadequacies in the Prediction of Torque Requirements for and Torque Output of Motor-Operated Butterfly Valves

ML031210639
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, Three Mile Island, 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, Fort Saint Vrain, Shoreham, Satsop, Trojan, Atlantic Nuclear Power Plant
Issue date:	09/28/1994
From:	Grimes B Office of Nuclear Reactor Regulation
To:
References
IN-94-069, NUDOCS 9409210211
Download: ML031210639 (9)

UNITED STATES

NUCLEAR REGULATORY COMMISSION

OFFICE OF NUCLEAR REACTOR REGULATION

WASHINGTON, D.C. 20555 September 28, 1994 NRC Information Notice 94-69: POTENTIAL INADEQUACIES IN THE PREDICTION OF

TORQUE REQUIREMENTS FOR AND TORQUE OUTPUT OF

MOTOR-OPERATED BUTTERFLY VALVES

Addressees

All holders of operating licenses or construction permits for nuclear power

reactors.

Purpose

The U.S. Nuclear Regulatory Commission (NRC) is issuing this information

notice to alert addressees to potential inadequacies in the prediction of

torque requirements for and torque output of motor-operated butterfly valves.

It is expected that recipients will review the information for applicability

to their facilities and consider actions, as appropriate, to avoid similar

events or problems. However, suggestions contained in this information notice

are not NRC requirements; therefore, no specific action or written response is

required.

Description of Circumstances

Several problems regarding inadequacies in the prediction of torque

requirements to operate butterfly valves and available torque from their motor

actuators have been reported through Generic Letter (GL) 89-10 reviews.

A significant example pertains to an event that occurred at the Catawba

nuclear power plant.

On February 25, 1993, the licensee for the Catawba facility determined that

both loops of the service water systems had been inoperable since August 1992, because three of the four service water pump discharge valves could not open

against the pump discharge pressure. In August 1992, the licensee had reduced

the torque switch settings on two of the four service water system discharge

valves (one in each train) to address a concern that, under minimum voltage

conditions, the motor operators for these valves might stall at a torque value

lower than the maximum torque setpoint. The new torque switch settings were

measured on a test bench and judged to be adequate based on manufacturer

sizing equations. Following this modification of the two valves, differential

pressure testing was not conducted to ensure the valves would function under

design-basis conditions.

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IN 94-69 September 28, 1994 The licensee determined that these valves failed to open at the established

torque output because the seat material had hardened with age and bearings had

degraded with raw water service. Such other variables as gearbox efficiency, application-specific flow characteristics, and packing friction also affect

the torque required to operate a butterfly valve. This event indicated that

the engineering analysis performed to derive the torque requirements of the

two referenced valves did not adequately address age degradation of the

valves.

Some significant problems at other nuclear power plants relating to torque

requirements of butterfly valves and available torque from their motor

actuators are discussed below:

- In March 1994, the licensee for the Perry facility found that certain

butterfly valves required higher seating torque than expected. Dynamic

testing showed that the bearing friction coefficient for certain

butterfly valves with stainless steel bushings was higher than the value

originally assumed (0.25) in the calculations. Specifically, the

bearing coefficient of friction was 0.634 for a fuel pool cooling and

cleanup valve with stainless steel bushings, and 0.334 for an emergency

service water valve with graphite-lubricated stainless steel bushings.

The licensee investigated the effect of this information on 17 motor- operated valves, the entire plant population of motor-operated butterfly

valves with stainless steel bushings. No operability problems were

found. However, the licensee is evaluating possible modifications to

improve margins for the four butterfly valves in the fuel pool cooling

and cleanup system.

- In November 1993, the licensee for the Palo Verde facility determined

that the condensate storage tank isolation valve would not have opened

or closed completely under design-basis conditions with the as-found

torque switch settings. The safety function of the valve is to isolate

the condensate storage tank should non-seismic piping rupture

downstream. The licensee also found that a containment isolation valve

would not have closed under design-basis conditions with the as-found

torque switch settings because the measured closing torque at torque

switch trip was less than the minimum torque required in accordance with

the design-basis calculation.

- In March 1993, the licensee for the Comanche Peak facility reported that

a valve in the containment hydrogen purge system had demonstrated a

lower torque output at torque switch trip during loaded testing on a

torque test stand than that delivered at torote switch trip during

static insitu testing. The licensee demonstrated that no operability

concern existed for this valve. However, this apparent reduction in

torque output at torque switch trip under loaded conditions for a

motor-operated butterfly valve could have implications for other motor- operated valves.

IN 94-69 September 28, 1994 - In May 1992, the licensee for the Zion facility determined that 12 of

the 15 butterfly valves in the service water system were inoperable

because their torque switch settings did not support the original design

basis maximum differential pressure of 862 kPa [125 psid]. The

remaining three valves would have supported a maximum differential

pressure of 862 kPa [125 psid]; however, it would not have supported the

current design requirement of 971 kPa [141 psid]. This event was caused

by deficiencies in the pre-service design installation testing.

- In March 1992, the licensee for the Grand Gulf facility determined that

the actuators for the suppression pool makeup system dump valves were

undersized (they could not meet the torque requirements). It was found

that the actuators were undersized because the flow rate specified in

the design specification for the valves, which was used by the valve

manufacturer to size the actuators, was the minimum required flow rate

to ensure a "post-loss of coolant accident" drywell vent coverage of at

least two feet above the top row vents with maximum emergency core

cooling systems pump-down of the suppression pool. The size of the

valves should have been determined using maximum expected design-basis

flow rate based on the actual configuration of the system.

- In March 1991, while performing diagnostic tests on a butterfly valve of

the primary containment purge and exhaust system, the licensee for the

Limerick facility discovered that the "as-found" torque switch setting

for the valve motor actuator was too low. This would have resulted in

the motor actuator tripping on high torque before the valve could

adequately close and seat if this valve was required to close during a

design-basis differential pressure condition. In addition, the testing

indicated that the actual motor actuator torque output for this valve

was lower than the design torque output requirement. As a result, the

valve would not have been capable of performing its primary containment

isolation design function. When the licensee reviewed the original

startup test records for all motor-operated butterfly valves in the same

system, it found eight other valves that did not meet the design torque

specifications for adequate valve seating in the event of a design basis

differential pressure condition, or for which no test data were

available to support the adequacy of butterfly valve testing.

Discussion

These examples of recent problems illustrate that many variables affecting the

application of butterfly valves, including flow, pressure, seat material

degradation, gearbox efficiency, turbulence in the system, as well as packing

and bearing frictions, can have an impact on the required tor;ue to operate a

butterfly valve and on the torque output of their motor actuators. A primary

basis for the NRC issuance of Generic Letter (GL) 89-10, "Safety-Related

Motor-Operated Valve Testing and Surveillance," with its request to test

safety-related motor-operated valves under design-basis conditions where

IN 94-69 September 28, 1994 practicable, is the uncertainties surrounding the prediction of torque/thrust

requirements by valve vendors.

Related Generic Communications

• NRC Information Notice 93-88, "Status of Motor-Operated Valve

Performance Prediction Program by the Electric Power Research

Institute," November 30, 1993

• NRC Information Notice 90-21, "Potential Failure of Motor-Operated

Butterfly Valves To Operate Because Valve Seat Friction Was

Underestimated," March 22, 1990

° NRC Information Notice 84-04, "Failure of Elastomer Seated Butterfly

Valves Used Only During Cold Shutdowns," January 18, 1984 This information notice requires no specific action or written response. If

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

one of the technical contacts listed below or the appropriate Office of

Nuclear Reactor Regulation (NRR) project manager.

Director 4cc

Division of Operating Reactor Support

Office of Nuclear Reactor Regulation

Technical contacts: Thomas G. Scarbrough, NRR

(301) 504-2794 William T. Orders, RII

(803) 383-4571 Perry C. Hopkins, RII

(803) 831-2963 Christine Lipa, RIII

(319) 851-5111 Attachment:

List of Recently Issued NRC Information Notices

444)' zJa

-Attachment

IN 94-69 September 28, 1994 LIST OF RECENTLY ISSUED

NRC INFORMATION NOTICES

Information Date of

Notice No. Subject Issuance Issued to

94-68 Safety-Related Equip- 09/27/94 All holders of OLs or CPs

ment Failures Caused by for nuclear power reactors.

Faulted Indicating Lamps

94-67 Problem with Henry 09/26/94 All holders of OLs or CPs

Pratt Motor-Operated for nuclear power reactors.

Butterfly Valves

94-66 Overspeed of Turbine- 09/19/94 All holders of OLs or CPs

Driven Pumps Caused by for nuclear power reactors.

Governor Valve Stem

Binding

94-65 Potential Errors in 09/12/94 All U.S. Nuclear Regulatory

Manual Brachytherapy Commission medical

Dose Calculations licensees.

Generated Using a

Computerized Treatment

Planning System

94-64 Reactivity Insertion 08/31/94 All holders of OLs or CPs

Transient and Accident for nuclear power reactors

Limits for High Burnup and all fuel fabrication

Fuel licensees.

94-63 Boric Acid Corrosion of 08/30/94 All holders of OLs or CPs

Charging Pump Casing for pressurized water

Caused by Cladding Cracks reactors.

94-62 Operational Experience 08/30/94 All holders of OLs or CPs

on Steam Generator Tube for pressurized water

Leaks and Tube Ruptures reactors.

94-61 Corrosion of William 08/25/94 All holders of OLs or CPs

Powell Gate Valve Disc for nuclear power reactors.

Holders

94-60 Potential Overpressuriza- 08/22/94 All holders of OLs or CPs

tion of Main Steam System for pressurized-water

reactors.

OL = Operating License

CP = Construction Permit

'~ IN 94-69 September 28, 1994 practicable, is the uncertainties surrounding the prediction of torque/thrust

requirements by valve vendors.

Related Generic Communications

° NRC Information Notice 93-88, "Status of Motor-Operated Valve

Performance Prediction Program by the Electric Power Research

Institute," November 30, 1993 o NRC Information Notice 90-21, "Potential Failure of Motor-Operated

Butterfly Valves To Operate Because Valve Seat Friction Was

Underestimated," March 22, 1990

° NRC Information Notice 84-04, "Failure of Elastomer Seated Butterfly

Valves Used Only During Cold Shutdowns," January 18, 1984 This information notice requires no specific action or written response. If

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

one of the technical contacts listed below or the appropriate Office of

Nuclear Reactor Regulation (NRR) project manager.

original signed by C.I. Grimes

Brian K. Grimes, Director

/ -Division of Operating Reactor Support

Office of Nuclear Reactor Regulation

Technical contacts: Thomas G. Scarbrough, NRR

(301) 504-2794 William T. Orders, RII

(803) 383-4571 Perry C. Hopkins, RII

(803) 831-2963 Christine Lipa, RIII

(319) 851-5111 Attachment:

List of Recently Issued NRC Information Notices

• See previous concurrences

OFFICE *EMEB:DE *EMEB:DE *EMEB:DE *EMEB:DE *DE:NRR

NAME MKhanna TScarbrough GJohnson RWessman BSheron

DATE [08/01/94 ]08/01/94 I--

108/02/94 I

[08/05/94 .08/26/94 OFFICE I*TECH ED I*OGCB:DORS I*OGCB:DORS IDORSN;.,

NAME IJMain TJKim EDoolittle BGrime I

DATE 1

108/31/94 09/01/94 09/07/94 109/2.1/94 J

DOCUMENT NAME: 94-b9.IN

IN 94-XX

September XX, 1994 practicable, is the uncertainties surrounding the prediction of torque/thrust

requirements by valve vendors.

Related Generic Communications

° NRC Information Notice 93-88, "Status of Motor-Operated Valve

Performance Prediction Program by the Electric Power Research

Institute," November 30, 1993

° NRC Information Notice 90-21, "Potential Failure of Motor-Operated

Butterfly Valves To Operate Because Valve Seat Friction Was

Underestimated," March 22, 1990

o NRC Information Notice 84-04, "Failure of Elastomer Seated Butterfly

Valves Used Only During Cold Shutdowns," January 18, 1984 This information notice requires no specific action or written response. If

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

one of the technical contacts listed below or the appropriate Office of

Nuclear Reactor Regulation (NRR) project manager.

Brian K. Grimes, Director

Division of Operating Reactor Support

Office of Nuclear Reactor Regulation

Technical Contacts: Thomas G. Scarbrough, NRR

(301) 504-2794 William T. Orders, RII

(803) 383-4571 Perry C. Hopkins, RII

(803) 831-2963 Christine Lipa, RIII

(319) 851-5111 Attachments:

List of Recently Issued NRC Information Notices

• See previous concurrences

OFFICE *EMEB:DE *EMEB:DE *EMEB:DE *EMEB:DE *DE:NRR

NAME MKhanna jTScarbrough GJohnson RWessman BSheron

DATE [08/01/94 J08/01/94 08/02/94 L08/05/94 .08/26/94

• 11

-

OFFICE I *TECH ED I *OGCB:DORS I *OGCB:DORS I DORS:NRR

NAME JMain TJKim EDoolittle BGrimes -

DATE 08/31/94 09/01/94 09/07/94 09/ /94

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IN 94-XX

September XX, 1994 practicable, is the uncertainties surrounding the prediction of torque/thrust

requirements by valve vendors. Licensees should remain aware of this basis

for GL 89-10 when setting motor-operated valves, including butterfly valves, based on vendor information, and scheduling followup dynamic testing.

Related Generic Communications

° NRC Information Notice 93-88, "Status of Motor-Operated Valve

Performance Prediction Program by the Electric Power Research

Institute," November 30, 1993

° NRC Information Notice 90-21, "Potential Failure of Motor-Operated

Butterfly Valves To Operate Because Valve Seat Friction Was

Underestimated," March 22, 1990

o NRC Information Notice 84-04, "Failure of Elastomer Seated Butterfly

Valves Used Only During Cold Shutdowns," January 18, 1984 This information notice requires no specific action or written response. If

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

one of the technical contacts listed below or the appropriate Office of

Nuclear Reactor Regulation (NRR) project manager.

Brian K. Grimes, Director

Division of Operating Reactor Support

Office of Nuclear Reactor Regulation

Technical Contacts: Thomas G. Scarbrough, NRR

(301) 504-2794 William T. Orders, RII

(803) 383-4571 Perry C. Hopkins, RII

(803) 831-2963 Attachments:

List of Recently Issued Information Notices

• See previous concurrences

OFFICE *EMEB:DE *EMEB:DE *EMEB:DE *EMEB:DE *DE:NRR

NAME MKhanna TScarbrough GJohnson RWessman BSheron

DATE L08/01/94 ]08/01/94

_ _ _ __ - _

I08/02/94 08/05/94 I

08/26/94 j

nFFTrr I *TECH4 FD OICM:DORS IOG6E&DORS IDORS:NRR

NAME JMain TJ KimR, EK e BGrimes

9ttl

DATE 08/31/94 09/ 1/94 09/7/94 09/ /94

IN 94-XX

August XX, 1994 practicable, is the uncertainties surrounding the prediction of torque/thrust

requirements by valve vendors. Licensees should remain aware of this basis

for GL 89-10 when setting motor-operated valves, including butterfly valves, based on vendor information, and scheduling follow-up dynamic testing.

Related Generic Communications

° NRC Information Notice 93-88, "Status of Motor-Operated Valve

Performance Prediction Program by the Electric Power Research

Institute," November 30, 1993

° NRC Information Notice 90-21, "Potential Failure of Motor-Operated

Butterfly Valves to Operate Because Valve Seat Friction Was

Underestimated," March 22, 1990

° NRC Information Notice 84-04, "Failure of Elastomer Seated Butterfly

Valves Used Only During Cold Shutdowns," January 18, 1984 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 contacts listed below or the appropriate Office of Nuclear

Reactor Regulation (NRR) project manager.

Brian K. Grimes, Director

Division of Operating Reactor Support

Office of Nuclear Reactor Regulation

Technical Contacts: Thomas G. Scarbrough, NRR

(301) 504-2794 William T. Orders, RII

(803) 383-4571 Perry C. Hopkins, RII

(803) 831-2963 Attachments:

List of Recently Issued Information Notices

• See previous concurrences -

OFFICE l *EMEB:DE *EMEB:DE *EMEB:DE *EMEB:DE D

NAME MKhanna TScarbrough GJohnson RWessman B

DATE 108/01/94 j08/01/94 J 08/02/94 J 08/05/94 108/1&/94J 4v v

OFFICE ITECH ED IOGCB:DORS IOGCB:DORS I

IDORS:NRR

NAME TJKi EDoolittle BGrimes

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