Information Notice 1987-61, Failure of Westinghouse W-2-Type Circuit Breaker Cell Switches

Failure of Westinghouse W-2-Type Circuit Breaker Cell Switches
	ML031130469
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, 05000000, Zimmer, Fort Saint Vrain, Shoreham, Satsop, Trojan, Atlantic Nuclear Power Plant
Issue date:	12/07/1987
From:	Rossi C; Office of Nuclear Reactor Regulation
To:	;
References
	IN-87-061, NUDOCS 8712010036
	Download: ML031130469 (8)
	v • d • e

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IN 87-61 UNITED STATES

NUCLEAR REGULATORY COMMISSION

OFFICE OF NUCLEAR REACTOR REGULATION

WASHINGTON, D.C. 20555 December 7, 1987 NRC INFORMATION NOTICE NO. 87-61: FAILURE OF WESTINGHOUSE W-2-TYPE

CIRCUIT BREAKER CELL SWITCHES

Addressees

All holders of operating licenses or construction permits for nuclear power

reactors.

Purpose

This information notice is being provided to alert addressees to potential

problems resulting from the failure of Westinghouse W-2-type circuit breaker

cell switches. 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 October 16, 1987, Westinghouse Electric Corporation notified the Nuclear

Regulatory Commission (NRC) staff, pursuant to the requirements of 10 CFR

Part 21, of the failure of a modified Westinghouse W-2-type switch that was

being utilized as a circuit breaker cell switch. The failure was identified

at Indian Point Station, Unit 3, on May 15, 1987, while the reactor was at

cold shutdown for a scheduled refueling outage. The output breaker for

emergency diesel generator (EDG) No. 31 was prevented from re-energizing

the 480-volt bus 2A after plant personnel had inadvertently de-energized

480-volt buses 2A and 5A. Subsequent investigation by the licensee determined

that an erroneous input to the EDG logic system had prevented the EDG output

breaker from closing. The licensee identified deformation of the spring

retainer in the spring-return mechanism of the cell switch in the 52/2A

breaker cell as the root cause of the erroneous input.

The spring retainer is continuously under stress whenever the breaker is

racked in (which it is,except when the breaker is racked out for testing

or maintenance) and releases whenever the breaker is racked out. Its

deformation allowed a loss of spring tension that rendered the cell switch

unable to spring-return to the racked out position when normal supply breaker

52/2A was racked out for maintenance. Thus, the EDG logic system received an

erroneous input indicating that breaker 52/2A was racked in and the main con- tacts were still closed. This erroneous input prevented the EDG No. 31 output

breaker from closing automatically in response to a loss of power. During

872106Z

IN 87-61 December 7, 1987 subsequent inspections by Indian Point personnel, 35 of a total of 37 similar

W-2-type switch spring retainers in the 480-volt system breakers exhibited

some sign of deformation.

All the cell switches had been shipped to Indian Point in 1971-1972 and all had

been in service for close to 15 years. The licensee reported the results of its

investigation to the NRC in Licensee Event Report 87-009-00 on October 2, 1987.

Discussion:

Westinghouse has determined (1) that the deformation of the spring retainer in

the spring-return mechanism of the cell switches was related to the aging of

the component and (2) that the failure mechanism was the continuous stress it

experiences while the breaker is racked in. The W-2-type cell switches are

available as optional equipment for all Westinghouse DS switchgear cabinets.

Westinghouse has indicated that inspection or testing performed. when the

breaker is racked out would determine if a failure has occurred. Where inspec- tions and/or testing have not been performed, the potential exists that if the

breaker is not racked in, a cell switch malfunction may prevent the completion

of safety-related functions dependent on cell switch indication of the breaker

being racked out or in the test position.

In the 10 CFR Part 21 notification submitted to the NRC, Westinghouse recommends

that proper cell switch operation'be verified through periodic inspections or

testing, or whenever the breaker is racked out. Proper operation of the spring

retainer- is only veriffable-when the-breaker--is-moved- fromr-ts-racked-iin-position.--

Visible inspection may be used to verify cell switch operation. However, it will

be necessary to move the breaker out on the rails to observe whether the switch

operating lever is in its proper position (30 degrees off. vertical for the W-2 cell switch). Any uncertainty in this observation may be resolved by manually

ensuring that the switch has returned to the proper position. Persons performing

this inspection should use caution not to contact any energized terminals.'

No specific action or written response is required by this information notice.

If you have any questions about this matter, please contact the technical

contact listed below or the Regional Administrator of the appropriate regional

office.

ares E.Rossi, Director

Division of 'Operational Events Assessment

Office of Nuclear Reactor'Regulation

Technical Contacts: K. R. Naidu, NRR

(301) 492-9656 Jaime Guillen, NRR

(301) 492-8933 Attachment: List of Recently Issued NRC Information Notices

Attachment

IN 87-61 December 7, 1987 LIST OF RECENTLY ISSUED

NRC INFORMATION NOTICES 1987 Information Date of

Notice No. Subject Issuance Issued to

87-60 Depressurization of Reactor 12/4/87 All holders of OLs

Coolant Systems in or CPs for PWRs.

Pressurized-Water Reactors86-108, Degradation of Reactor 11/19/87 All holders of OLs

Supp. 2 Coolant System Pressure or CPs for nuclear

Boundary Resulting from power reactors.

Boric Acid Corrosion

87-59 Potential RHR Pump Loss 11/17/87 All holders of OLs

or CPs for nuclear

power reactors.

87-58 Continuous Communications 11/16/87 All nuclear power

Following Emergency reactor facilities

Notifications holding an OL and

the following fuel

facilities that have

Emergency Notification

!: -~ .: -, .- Systems: Nuclear

Fuel Services, Erwin, TN; General Atomics, San Diego, CA; UNC,

Montville, CT; and

B & W LRC and B & W

Navy, Lynchburg, VA.

87-57 Loss of Emergency Boration 11/6/87 All holders of OLs

Capability Due to Nitrogen or CPs for nuclear

Gas Intrusion power reactors.

87-56 Improper Hydraulic Control 11/4/87 All holders of OLs

Unit Installation at BWR or CPs for boiling

Plants. water reactors (BWRs).

87-55 Portable Moisture/Density 10/29/87 All NRC licensees

Gauges: Recent Incidents authorized to

of Portable Gauges Being possess portable

Stolen or Lost gauges.

87-54 Emergency Response Exercises 10/23/87 All holders of OLs

or CPs for nuclear

power reactors.

OL = Operating License

CP = Construction Permit

IN 87-61 December 7, 1987 subsequent inspections by Indian Point personnel, 35 of a total of 37 similar

W-2-type switch spring retainers in the 480-volt system breakers exhibited

some sign of deformation.

All the cell switches had been shipped to Indian Point in 1971-1972 and all had

been in service for close to 15 years. The licensee reported the results of its

investigation to the NRC in Licensee Event Report 87-009-00 on October 2, 1987.

Discussion:

Westinghouse has determined (1) that the deformation of the spring retainer in

the spring-return mechanism of the cell switches was related to the aging of

the component and (2) that the failure mechanism was the continuous stress it

experiences while the breaker is racked in. The W-2-type cell switches are

available as optional equipment for all Westinghouse DS switchgear cabinets.

Westinghouse has indicated that inspection or testing performed when the

breaker is racked out would determine if a failure has occurred. Where inspec- tions and/or testing have not been performed, the potential exists that if the

breaker is not racked in, a cell switch malfunction may prevent the completion

of safety-related functions dependent on cell switch indication of the breaker

being racked out or in the test position.

In the 10 CFR Part 21 notification submitted to the NRC, Westinghouse recommends

that proper cell switch operation be verified through periodic inspections or

testing, or whenever the breaker is racked out. Proper operation of the spring

retainer is only verifiable when the breaker is moved from its racked in position.

Visible inspection may be used to verify cell switch operation. However, it will

be necessary to move the breaker out on the rails to observe whether the switch

operating lever is in its proper position (30 degrees off vertical for the W-2 cell switch). Any uncertainty in this observation may be resolved by manually

ensuring that the switch has returned to the proper position. Persons performing

this inspection should use caution not to contact any energized terminals.

No specific action or written response is required by this information notice.

If you have any questions about this matter, please contact the technical

contact listed below or the Regional Administrator of the appropriate regional

office.

Charles E. Rossi, Director

Division of Operational Events Assessment

Office of Nuclear Reactor Regulation

Technical Contacts: K. R. Naidu, NRR

(301) 492-9656 Jaime Guillen, NRR

(301) 492-8933 Attachment: List of Recently Issued NRC Information Notices

SEE PREVIOUS CONCURRENCES

OGCB:DOEA:NRRtVIB:DRIS:NRR *SELB:DEST:NRR*PPMB:ARM*C/OGCB:DOEA:NRR NR

JGuillen KNaidu FRosa TechEd CHBerlinger CERossi

11/03/87 11/ /87 11/06/87 10/31/87 11/20/87 12// /87

IN 87-XX

November xx, 1987 All the cell switches had been shipped to Indian Point In 1971-1972 and all had

been in service for close to 15 years. The licensee reported the results of

its investigation to the NRC in Licensee Event Report 87-009-00 on October 2,

1987.