Information Notice 1996-24, Preconditioning of Molded-Case Circuit Breakers Before Surveillance Testing

Preconditioning of Molded-Case Circuit Breakers Before Surveillance Testing

ML031060110
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:	04/25/1996
From:	Grimes B Office of Nuclear Reactor Regulation
To:
References
IN-96-024, NUDOCS 9604220229
Download: ML031060110 (14)

UNITED STATES

NUCLEAR REGULATORY COMMISSION

OFFICE OF NUCLEAR REACTOR REGULATION

WASHINGTON, D.C.

20555-0001

April 25, 1996

NRC INFORMATION NOTICE 96-24: PRECONDITIONING 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 detrimental effect that preconditioning of

molded-case circuit breakers could have on the diagnostic validity of

surveillance tests.

It is expected that recipients will review this

information for applicability to their facilities and consider actions, as

appropriate, to avoid similar problbms.

However, suggestions contained in

this information notice are not NRC requirements; therefore, no specific

action or written response is required.

DescriDtion of Circumstances

During an inspection at the Diablo Canyon Nuclear Power Plant (IR 50-275,

323/94-27 dated December 21, 1994), NRC inspectors noted that the licensee

preconditioned circuit breakers before performing surveillance testing.

Before the overcurrent trip testing, Diablo Canyon staff exercised the circuit

breakers by manually opening and closing them three times. The plant staff

'did not record the as-found condition of the breakers in terms of unexercised

trip currents and times.

During another inspection at the South Texas Project (IR 50-498, 499/94-35 dated January 19, 1995), NRC inspectors noted that the licensee exercised

similar circuit breakers manually at least five times before testing the

overcurrent trip unit.

Discussion

A molded-case circuit breaker is one of the most widely used protective

devices for electrical circuits at nuclear power plants.

Its proper operation

is essential for the protection and safe operation of plant electrical

equipment. Many circuit breakers are continuously energized for long periods.

Often they are in service for years and are rarely, if ever, called upon to

perform a protective function.

Nevertheless, when needed, they must rapidly

isolate a faulted or overloaded circuit to prevent equipment damage.

Therefore, for the safe operation of the electrical distribution system

equipment of a nuclear power plant, it is important to periodically verify

their continued reliability.

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IN 96-24 April 25, 1996 Periodic inspection and testing of circuit breakers in their as-found

condition is an appropriate way of demonstrating the functional operability of

the breaker and of detecting any degradation. However, the practice of

preconditioning before testing (e.g., lubricating pivot points and manually

cycling the breaker) defeats the purpose of the periodic test. Such

preconditioning does not confirm continued operability between tests nor does

it provide information on the condition of the circuit breaker for trending

purposes.

Testing some circuit breakers in the as-found condition can provide

useful data on which to base decisions on surveillance intervals and the

ability of the untested circuit breakers to perform their intended function.

Since only a fraction of the circuit breakers are tested each refueling outage

to justify the operability of the remaining circuit breakers, preconditioning

before testing does not provide the expected assurance of the operability of

remaining breakers which are not tested.

By preconditioning circuit breakers, useful information may be lost because the breaker may not have been capable

of performing its intended function without preconditioning.

To correct this situation, Diablo Canyon Power Plant plans to revise the

electrical maintenance procedure before the next surveillance test has to be

performed.

The revised procedures will state that electrical testing should

be performed before any intentional manual exercising of the breakers, and to

ensure that electrical testing on breakers with removable trip units is

performed before removing the trip unit.

Some plants have older technical specification bases that cite National

Electrical Manufacturers Association (NEMA) Standard AB 2-1980. This version

of the standard specifies mechanical cycling of circuit breakers prior to

electrical testing.

In later versions of this standard, this procedure was

deleted. There appears to be no valid technical need for mechanical cycling

prior to electrical surveillance testing.

The NRC has issued other generic communications on molded-case circuit breaker

applications and testing:

NRC Information Notice (IN) 92-51, and its

Supplement 1, "Misapplication and Inadequate Testing of Molded-Case Circuit

Breakers;" IN 93-26, "Grease Solidification Causes Molded Case Circuit Breaker

Failure to Close;" and IN 93-64, "Periodic Testing and Preventive Maintenance

of Molded-Case Circuit Breakers."

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IN 96-24 April 25, 1996 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.

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Brian K. Grimes, Acting Director

Division of Reactor Program Management

Office of Nuclear Reactor Regulation

Technical contacts:

Sikhindra Mitra, NRR

(301) 415-2783 Internet:skml@nrc.gov

Steve Alexander, NRR

(301) 415-2995 Internet:sda@nrc.gov

Christopher Myers, RIV

(817) 860-8144 Internet:cjm@nrc.gov

Attachment:

List of Recently Issued NRC Information Notices

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Attachment

IN 96-24

April 25, 1996 LIST OF RECENTLY ISSUED

NRC INFORMATION NOTICES

Information

Date of

Notice No.

Subject

Issuance

Issued to

96-23

96-22

96-21

96-20

Fires in Emergency Diesel

Generator Exciters During

Operation Following Unde- tected Fuse Blowing

Improper Equipment Set- tings Due to the Use of

Nontemperature-Compensated

Test Equipment

Safety Concerns Related

to the Design of the Door

Interlock Circuit on

Nucletron High-Dose Rate

and Pulsed Dose Rate

Remote Afterloading

Brachytherapy Devices

Demonstration of Associ- ated Equipment Compliance

with 10 CFR 34.20

Failure of Tone Alert

Radios to Activate When

Receiving a Shortened

Activation Signal

Compliance with 10 CFR

Part 20 for Airborne

Thorium

Loss of Reactor Coolant

Inventory and Potential

Loss of Emergency Mitiga- tion Functions While in a

Shutdown Condition

04/22/96

04/11/96

04/10/96

04/04/96

04/02/96

03/25/96

03/25/96

All holders of OLs or CPs

for nuclear power reactors

All holders of OLs or CPs

for nuclear power reactors

All U.S. NRC Medical to the

Licensees authorized to use

brachytherapy sources in

high- and pulsed-dose-rate

remote afterloaders

All industrial radiography

licensees and radiography

equipment manufacturers

All holders of OLs or CPs

for nuclear power reactors

All material licensees

authorized to possess and

use thorium in unsealed

form

All holders of OLs or CPs

for PWR power plants

96-19

96-18

95-03 Supp. 1 OL = Operating License

CP - Construction Permit

K2

2 IN 96-24 April 25, 1996 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, Acting Director

Division of Reactor Program Management

Office of Nuclear Reactor Regulation

Technical contacts:

Sikhindra Mitra, NRR

(301) 415-2783 Internet:skml@nrc.gov

Steve Alexander, NRR

(301) 415-2995 Internet:sda@nrc.gov

Christopher Myers, RIV

(817) 860-8144 Internet:cjm@nrc.gov

Attachment:

List of Recently Issued NRC Information Notices

DOCUMENT NAME:

96-24.IN

Tech Editor reviewed 9/21/95 To receive a copy of this document, Indicate In the box: 'C'

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4/15/96

4/22/96

4/LT/96

OFFICIAL RECORD COPY

IN 96-XX

April XX, 1996 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.

Dennis M. Crutchfield, Director

Division of Reactor Program Management

Office of Nuclear Reactor Regulation

Technical contacts: Sikhindra Mitra, NRR

(301) 415-2783 Internet: skmlnrc.gov

Christopher Myers, RIV

(817) 860-8144 Internet: cjm@nrc.gov

Steve Alexander, NRR

(301) 415-2995 Internet: sda@nrc.gov

Attachment:

List of Recently Issued NRC Information Notices

DOCUMENT NAME:

95-XX.IN

To receive a copy of this document. Indicate In the box:

Tech Editor reviewed 9/21/95

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April XX, 1996 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.

Dennis M. Crutchfield, Director

Division of Reactor Program Management

Office of Nuclear Reactor Regulation

Technical contacts: Sikhindra Mitra, NRR

(301) 415-2783 Internet: skmlnrc.gov

Christopher Myers, RIV

(817) 860-8144 Internet: cjm~nrc.gov

Attachment:

List of Recently Issued NRC Information Notices

DOCUMENT NAME: 95-XX.IN

Tech Editor reviewed 9/21/95 To receive a copy of this document, Indicate In the box: 'C' - Copy without enclosures 'E' - Copy with enclosures 'No = No copy

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OFFICIAL RECORD COPY

IN 96-XX

April XX, 1996 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.

Dennis M. Crutchfield, Director

Division of Reactor Program Management

Office of Nuclear Reactor Regulation

Technical contacts:

Christopher Myers, RIV

(817) 860-8144

Sikhindra Mitra, NRR

(301) 415-2783 Attachment:

List of Recently Issued NRC Information Notices

DOCUMENT NAME:

95-XX.IN

Tech Editor reviewed 9/21/95 To receive a copy of this document. Indicate In the box: wCw = Copy without enclosures 'E" - Copy with enclosures 'N'= No copy

OFFICE

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4/ /96

OFFICIAL RECORD COPY

IN 96-XX

April xx, 1996 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.

Dennis M. Crutchfield, Director

Division of Reactor Program Management

Office of Nuclear Reactor Regulation

Technical contacts:

Tom Westerman, RIV

(817) 860-8145

Christopher Myers, RIV

(817) 860-8144

Stephen Alexander, NRR

(301) 415-2995

Sikhindra Mitra, NRR

(301) 415-2783 Attachment:

List of Recently Issued NRC Information Notices

DOCUMENT NAME: 95-XX.IN

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IN 96-XX

January xx, 1995 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.

Dennis M. Crutchfield, Director

Division of Reactor Program Management

Office of Nuclear Reactor Regulation

Technical contacts:

Tom Westerman, RIV

(817) 860-8145

Christopher Myers, RIV

(817) 860-8144

Stephen Alexander, NRR

(301) 415-2995 Sikhindra Mitra,

(301) 415-2783 NRR

Attachment:

List of Recently Issued NRC Information Notices

DOCUMENT NAME:

95-XX.IN

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IN 95-XX

September xx, 1995

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.

Dennis M. Crutchfield, Director

Division of Reactor Program Management

Office of Nuclear Reactor Regulation

Technical contacts:

Tom Westerman, RIV

(817) 860-8145 Christopher Myers,

(817) 860-8144 RIV

Stephen Alexander, NRR

(301) 415-2995

Sikhindra Mitra, NRR

(301) 415-2783 Attachment:

List of Recently Issued NRC Information Notices

DOCUMENT NAME: 95-XX.IN

Te raclva a etonw of thb document Indicate hI Om box: 'C'

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OFFICIAL RECORD COPY

IN 95-XX

September xx, 1995 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, Deputy Director

Division of Reactor Program Management

Office of Nuclear Reactor Regulation

Technical Contacts: Tom Westerman, RIV

(817) 860-8145

Christopher Myers, RIV

(817) 860-8144

Stephen Alexander, NRR

(301) 415-2995

Sikhindra Mitra, NRR

(301) 415-2783 Attachment:

List of Recently Issued NRC Information Notices

DOCUMENT NAME: 95-XX.IN

• , See previous concurrence

To receive a copy of this document. Indicate In the box: 'C'

Copy without enclosures

E' - Copy with enclosures

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IN 95-XX

August XX, 1995 one of the technical contacts listed below or the appropriate Office of

Nuclear Reactor Regulation (NRR) project manager.

Brian K. Grimes, Deputy Director

Division of Reactor Program Management

Office of Nuclear Reactor Regulation

Technical Contacts:

Tom Westerman, RIV

(817) 860-8145

Christopher Myers, RIV

(817) 860-8144

Stephen Alexander, NRR

(301) 415-2995

Sikhindra Mitra, NRR

(301) 415-2783 Attachment:

List of Recently Issued NRC Information Notices

DOCUMENT NAME:

95-XX.IN

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donument. indicate In the box:

• . See previous concurrence

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OFFICIAL RECORD COPY

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IN 95-XX

August XX, 1995 one of the technical contacts listed below or the

Nuclear Reactor Regulation (NRR) project manager.

appropriate Office of

Brian K. Grimes, Deputy Director

Division of Reactor Program Management

Office of Nuclear Reactor Regulation

Technical Contacts:

Tom Westerman, RIV

(817) 860-8145

Christopher Myers, RIV

(817) 860-8144

Stephen Alexander, NRR

(301). 415-2995

Sikhindra Mitra, NRR

(301) 415-2783 Attachment:

List of Recently Issued NRC Information Notices

DOCUMENT NAME:

95-XX.IN

To receive a copy of this document. Indicate In the box:

• = See previous concurrence

wEd - Copy with oncosurss

rW - No copy

NCR - Copy without endosurms

OFFICE

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