Information Notice 1993-64, Periodic Testing and Preventive Maintenance of Molded Case Circuit Breakers

Periodic Testing and Preventive Maintenance of Molded Case Circuit Breakers
	ML031070177
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, Fort Saint Vrain, Shoreham, Satsop, Trojan, Atlantic Nuclear Power Plant, Crane
Issue date:	08/12/1993
From:	Grimes B; Office of Nuclear Reactor Regulation
To:	;
References
	IN-93-064, NUDOCS 9308060237
	Download: ML031070177 (11)
	v • d • e

UNITED STATES

NUCLEAR REGULATORY COMMISSION

OFFICE OF NUCLEAR REACTOR REGULATION

WASHINGTON, D.C.

20555

August 12, 1993

NRC INFORMATION NOTICE 93-64:

PERIODIC TESTING AND PREVENTIVE MAINTENANCE

OF MOLDED CASE CIRCUIT BREAKERS

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 the problem of age-related degradation of molded

case circuit breakers (MCCBs) and to provide sources of information on MCCB

periodic testing and preventive maintenance. 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 are not NRC requirements; therefore, no

specific action or written response is required.

Description of Circumstances

Kewaunee

During special testing in 1992 of 35 spare Westinghouse Type EB and EHB MCCBs

at the Kewaunee Nuclear Power Plant, 10 of the MCCBs tripped late in thermal

trip tests at 300-percent overcurrent and 1 of the 10 failed to trip below the

maximum allowable trip current in an instantaneous magnetic trip test.

Subsequent testing during the 1992 outage showed a similar percentage of out- of-tolerance MCCBs.

Because the MCCBs were available for use in safety- related and fire protection applications, the licensee reported the

circumstances as an item of generic interest in Licensee Event Report (LER)

50-305/92-01.

The licensee attributed the out-of-tolerance trip values to age-related

degradation and infrequent exercising of the MCCBs, some of which had not been

exercised since initial plant startup in 1974.. Sometimes-retests were

successful after the breaker was exercised manually, which is one type of

preventive maintenance recommended by manufacturers and industry standards.

However, without periodic testing, the degraded condition of the MCCBs was not

detected earlier.

The licensee replaced the Type EB and EHB breakers in

service and plans to implement a program at Kewaunee to 'test and exercise

safety-related MCCBs periodically starting in August 1993.

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Au-gust 12, 1991 Zion

An NRC diagnostic evaluation team at the Zion Nuclear Station observed that

the licensee had no program for routinely testing MCCBs (U.S. Nuclear

Regulatory Commission, "Diagnostic Evaluation Team Report for Zion Nuclear

Power Station," August 1990).

Many breakers had been in service for more than

20 years without being exercised or tested so the potential existed for

undetected degradation that could impair the performance of safety-related

systems.

Discussion

As a followup to the Zion evaluation, the NRC conducted an industry-wide study

of MCCB performance history, reported in "Review of Operational Experience

with Molded Case Circuit Breakers in U.S. Commercial Nuclear Power Plants"

(June 1992).

The study found that for the analyzed failure modes, most of the

failure rates fell below those estimated generically in The Institute of

Electrical and Electronics Engineers (IEEE) Std 500-1984, "IEEE Guide to the

Collection and Presentation of Electrical, Electronic, and Sensing Component

Reliability Data for Nuclear Power Generating Stations."

The study also noted

that, except for limited cases, there are no general technical specification

requirements for periodic testing and preventive maintenance of safety-related

MCCBs.

Some plant-specific technical specifications require testing certain

MCCBs used only for overcurrent protection for electrical containment

penetrations, but the testing is limited, and not all of the circuits are

safety-related.

The study found that despite manufacturer recommendations and

industry standards, many plants do not perform periodic testing or preventive

maintenance on safety-related MCCBs, and for the few-that do, frequency and

procedures differ widely.

In addition, as part of its aging research program, the NRC sponsored a study

reported in March 1992 in NUREG/CR-5762, "Comprehensive Aging Assessment Study

of Circuit Breakers and Relays," that evaluated various inspection, surveillance, and monitoring techniques and preventive maintenance practices.

The study found that MCCB preventive maintenance practices (such as manual

exercising), can mitigate the effects of aging and'help ensure continued MCCB

reliability.

However, manual exercising alone was not found effective in

detecting or assessing age-related degradation.

Detecting or assessing

degradation, the study found, could only be accomplished through appropriate

periodic testing and monitoring.

Certain standard MCCB tests (such as

individual pole resistance, 300-percent thermal overload, and instantaneous

magnetic trip tests) performed periodically were found effective along with

the additional techniques of infrared temperature measurement and vibration

testing.

An example of the industry standards that address periodic testing and

preventive maintenance is IEEE Std 308-1974, "IEEE Standard Criteria for Class

1E Power Systems for Nuclear Power Generating Stations" (endorsed by

August 12, 1993 Regulatory Guide 1.32, Revision 2, February 1977).

Its Section 6.3 as well as

Section 7.4.1 of the current (1991)

edition of the standard recommend that

periodic tests be performed at scheduled intervals to detect the deterioration

of the equipment and to demonstrate operability of the components that are not

exercised during normal operation.

Other industry standards and publications

that contain recommendations for testing and maintenance of MCCBs include the

following:

American National Standards Institute (ANSI)/IEEE Std 242-1986, "IEEE

Recommended Practice for Protection and Coordination of Industrial and

Commercial Power Systems"

ANSI/National Fire Protection Association (NFPA) 70B-1990, "Recommended

Practice for Electrical Equipment Maintenance"

National Electrical Manufacturers Association (NEMA) Standard

Publication No. AB 4-1991, "Guidelines for Inspection and Preventive

Maintenance of Molded Case Circuit Breakers Used in Commercial and

Industrial Applications"

Electric Power Research Institute (EPRI) Report NP-7410, "Breaker

Maintenance," Volume 3, "Molded-Case Circuit Breakers," September 1991 The recommendations of these publications may not be applicable in every

instance, depending on the specific components installed, their functions, and

their environment.

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:

Sikhindra K. Mitra, NRR

(301)

504-2783

Stephen D. Alexander, NRR

(301) 504-2995

Satish K. Aggarwal, RES

(301) 492-3829 Attachment:

List of Recently Issued NRC Information Notices

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IN 93-64

August 12, 1993

Page I of I

LIST OF RECENTLY ISSUED

NRC INFORMATION NOTICES

Information

Date of

Notice No.

Subject

Issuance

Issued to

93-63 Improper Use of Soluble

08/11/93

All holders of OLs or CPs

Weld Purge Dam Material

for nuclear power reactors.

93-62 Thermal Stratification

08/10/93 All holders of OLs or CPs (

of Water in BWR Reactor

for boiling water reactors .

Vessels

93-61 Excessive Reactor Coolant

08/09/93

All holders of OLs or CPs

Leakage Following A Seal

for nuclear power reactors.

Failure in A Reactor

Coolant Pump or Reactor

Recirculation Pump

93-60

Reporting Fuel Cycle and

08/04/93

All fuel cycle and materials

Materials Events to the

licensees.

NRC Operations Center

93-59 Unexpected Opening of

07/26/93

All holders of OLs or CPs

Both Doors in An

for nuclear power reactors.

Airlock

93-58 Nonconservatism in Low-

07/26/93

All holders of OLs or CPs

Temperature Overpressure

for pressurized-water

Protection for Pressurized- reactors.

Water Reactors

93-57 Software Problems

07/23/93

All holders of OLs or CPs

Involving Digital

for test and research

Control Console Systems

reactors and nuclear power

at Non-Power Reactors

reactors.

Q

93-56 Weakness in Emergency

07/22/93

All holders of OLs or CPs

Operating Procedures

for pressurized water

Found as Result of

reactors.

Steam Generator Tube

Rupture

93-55 Potential Problem with

07/21/93

All holders of OLs or CPs

Main Steamline Break

for pressurized water

Analysis for Main Steam

reactors.

Vaults/Tunnels

UL - Operating License

CP -

Construction Permit

N 93-64 V-

(ugust 12, 1993 Regulatory Guide 1.32, Revision 2, February 1977).

Its Section 6.3 as well as

Section 7.4.1 of the current (1991)

edition of the standard recommend that

periodic tests be performed at scheduled intervals to detect the deterioration

of the equipment and to demonstrate operability of the components that are not

exercised during normal operation. Other industry standards and publications

that contain recommendations for testing and maintenance of MCCBs include the

following:

American National Standards Institute (ANSI)/IEEE Std 242-1986, "IEEE

Recommended Practice for Protection and Coordination of Industrial and

Commercial Power Systems"

ANSI/National Fire Protection Association (NFPA) 70B-1990, "Recommended

Practice for Electrical Equipment Maintenance"

National Electrical Manufacturers Association (NEMA) Standard

Publication No. AB 4-1991, "Guidelines for Inspection and Preventive

Maintenance of Molded Case Circuit Breakers Used in Commercial and

Industrial Applications"

Electric Power Research Institute (EPRI) Report NP-7410, "Breaker

Maintenance," Volume 3, "Molded-Case Circuit Breakers," September 1991 The recommendations of these publications may not be applicable in every

instance, depending on the specific components installed, their functions, and

their environment.

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

Brian K. Grimes, Director Brian K. Grimes

Division of Operating Reactor Support

Office of Nuclear Reactor Regulation

Technical contacts:

Sikhindra K. Mitra, NRR

(301)

504-2783 Stephen D. Alexander, NRR

(301) 504-2995

Satish K. Aggarwal, RES

(301) 492-3829 Attachment:

List of Recently Issued NRC Information Notices

See previous concurrence

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Industrial Applications"

Electric Power Research Institute (EPRI) Report NP-7410, "Breaker

Maintenance," Volume 3, "Molded-Case Circuit Breakers," September 1991 Note that the recommendations of these publications may not be applicable in

every instance, depending on the specific components installed, their

functions, and their environment.

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:

Sikhindra K. Mitra, NRR

(301) 504-2783

Stephen D. Alexander, NRR

(301) 504-2995

Satish K. Aggarwal, RES

(301) 492-3829 Attachment:

List of Recently Issued NRC Information Notices

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National Electrical Manufacturers Association (NEMA) Standard

Publication No. AB 4-1991, "Guidelines for Inspection and Preventive

Maintenance of Molded Case Circuit Breakers Used in Commercial and

Industrial Applications"

Electric Power Research Institute (EPRI) Report NP-7410, "Breaker

Maintenance," Volume 3, "Molded-Case Circuit Breakers," September 1991 Note that the recommendations of these publications may not be applicable in

every instance, depending on the specific components installed, their

functions, and their environment.

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:

Sikhindra K. Mitra, NRR

(301) 504-2783

Stephen D. Alexander, NRR

(301) 504-2995

Satish K. Aggarwal, RES

(301) 492-3829 Attachment:

List of Recently Issued NRC Information Notices

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ANSI/National Fire Protection Association (NFPA) 70B-1990, "Recommended

Practice for Electrical Equipment Maintenance"

National Electrical Manufacturers Association (NEMA) Standard

Publication No. AB 4-1991,

"Guidelines for Inspection and Preventive

Maintenance of Molded Case Circuit Breakers Used in Commercial and

Industrial Applications" and

Electric Power Research Institute (EPRI) Report NP-7410, "Breaker

Maintenance," Volume 3, "Molded-Case Circuit Breakers," September 1991 These manufacturers' arecommendations and industry standards provide guidance

on "good practices" for performing testing and maintenance of MCCBs.

However, their recommended practices for frequency and method of testing and

maintenance of MCCBs are not necessarily applicable to the MCCBs at every

nuclear plant because the specific tests and their frequencies depend on the

specific components installed, their functions, and their environment.

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 Office of Nuclear

Reactor Regulation project manager.

Brian K. Grimes, Director

Division of Operating Reactor Support

Office of Nuclear Reactor Regulation

Technical contact:

Sikhindra K. Mitra, NRR/EELB

(301) 504-2783 Attachments:

1. Referenced Codes and Standards

2. List of Recently Issued NRC Information Notices

See previous concurrence

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June xx, 1993 Section 6.3 of IEEE Std 308-1974, "IEEE Standard Criteria for Class 1E Power

Systems for Nuclear Power Generating Stations," which is endorsed by

Regulatory Guide 1.32, Revision 2, February 1977, recommends that periodic

tests be performed at scheduled intervals to detect the deterioration of the

equipment toward an unacceptable condition and to demonstrate operability of

the components that are not exercised during normal operation.

The regulatory guides, industry standards, and manufacturers' recommended

practices for frequency and method of testing and maintenance of MCCBs are not

necessarily applicable to the MCCBs at every nuclear plant because the

specific tests and their frequencies depend on the specific components

installed, their functions, and their environment.

However, guidance on "good

practices" for performing testing and maintenance of MCCBs is provided in

these manufacturers' recommendations and industry standards.

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 Office of Nuclear

Reactor Regulation project manager.

Brian K. Grimes, Director

Division of Operating Reactor Support

Office of Nuclear Reactor Regulation

Technical contact: Sikhindra K. Mitra, NRR/EELB

(301) 504-2783 Attachments:

1. Referenced Codes and Standards

2. List of Recently Issued NRC Information Notices

See previous concurrence

OFC

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