Information Notice 1988-44, Mechanical Binding of Spring Release Device in Westinghouse Type DS-416 Circuit Breakers

Mechanical Binding of Spring Release Device in Westinghouse Type DS-416 Circuit Breakers

ML031150209
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:	06/24/1988
From:	Rossi C Office of Nuclear Reactor Regulation
To:
References
IN-88-044, NUDOCS 8806210038
Download: ML031150209 (5)

UNITED STATES

NUCLEAR REGULATORY COMMISSION

OFFICE OF NUCLEAR REACTOR REGULATION

WASHINGTON, D.C. 20555 June 24, 1988 NRC INFORMATION NOTICE NO. 88-44: MECHANICAL BINDING OF SPRING RELEASE DEVICE

IN WESTINGHOUSE TYPE DS-416 CIRCUIT BREAKERS

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 mechanical binding of the spring release device

(SRD) in Westinghouse type DS-416 metal clad circuit breakers. It is expected

that recipients will review the information for applicability to their facili- ties and consider actions, as appropriate, to avoid similar problems. However, suggestions contained in this information notice do not constitute NRC require- ments; therefore, no specific action or written response is required.

Description of Circumstances

On May 25, '1988, the South Texas Project Unit 1 (STP-1 or licensee) performed a

loss-of-offsite power test. During this test, two Class IE electrical circuit

breakers failed to reclose as required during load sequencing. Subsequent in- vestigation by the licensee identified the failed breakers as Westinghouse type

DS-416 metal clad breakers. These DS-416 electrical breakers are located in

main 480-Vac load centers and are tie and feeder breakers for 480-Vac components.

The breaker has an SRD that initiates the sequence for the breaker closing.

The SRD is attached to the breaker housing and is comprised of a coil housing

that is attached to the breaker casing, a closing coil, and a lever that is

attached to the coil housing. The lever travels up and down through a window

(a punched out opening) in the breaker casing. When the breaker is signaled

to close, the coil is energized and the lever is designed to move up and make

contact with the spring release latch that mechanically releases the breaker

closing springs. These SRDs also are used in Westinghouse type DS-420 and

DS-206 circuit breakers.

Discussion:

The licensee's preliminary investigation indicates that the breakers failed to

reclose because the closing coils had overheated and burned out. The licensee

880621003

IN 88-44 June 24, 1988 believes that the coils burned out as a result of mechanical binding between

the lever and the edge of the breaker casing window. The licensee physically

inspected and electrically tested 28 other DS-416 breakers installed in Unit 1 and 18 breakers installed in Unit 2 as of June 16, 1988, and identified 10 ad- ditional cases where the lever and the edge'of the breaker casing window were

making contact.

Although the root cause of the binding has not been determined, the licensee

has taken several steps to alleviate the problem. The licensee has replaced

the SRD in the STP-1 breakers that indicated signs of possible binding and has

verified that the clearances between the lever and the casing are sufficient

to preclude further binding. In addition, the licensee has extensively briefed

the STP control room personnel on this binding problem. It should be noted

that although the SRD may bind, it is still possible to manually trip the

breaker closing springs by pushing the "CLOSE" button located at the circuit

breaker.

The licensee has contacted Westinghouse for assistance in determining the root

cause of the binding. The NRC will remain cognizant of any new developments

and await the results of the South Texas and Westinghouse investigation. The

NRC will issue a further generic communication if warranted by the availability

of additional information or if additional regulatory action is'deemed necessary.

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

If you have any questions about this matter, please contact one of the techni- cal contacts listed below or the Regional-Administrator-af-the-appropriate- regional office.

J0

Charles E. Rossi, Director

Division'of Operational Events Assessment

Office of Nuclear Reactor Regulation

Technical Contacts: Kamal Naidu, NRR

(301) 492-0980

Jaime Guillen, NRR

(301) 492-1170 'I

Attachment: List of Recently Issued NRC Information Notices

Attachment

IN 88-44 June 24, 1988 LIST OF RECENTLY ISSUED

NRC INFORMATION NOTICES

Information Date of

Notice No. Subject Issuance Issued to

88-43 Solenoid Valve Problems 6/23/88 All holders of OLs

or CPs for nuclear

power reactors.

88-42 Circuit Breaker Failures 6/23/88 All holders of OLs

Due to Loose Charging or CPs for nuclear

Spring Motor Mounting Bolts power reactors.

88-41 Physical Protection 6/22/88 All holders of OLs

Weaknesses Identified or CPs for nuclear

Through Regulatory Ef- power reactors.

fectiveness Reviews (RERs)

88-40 Examiners' Handbook for 6/22/88 All holders of OLs

Developing Operator or CPs for nuclear

Licensing Examinations power reactors.

88-39 LaSalle Unit 2 Loss of 6/15/88 All holders of OLs

Recirculation Pumps With or CPs for BWRs.

Power Oscillation Event

88-38 Failure of Undervoltage 6/15/88 All holders of OLs

Trip Attachment on General or CPs for nuclear

Electric Circuit Breakers power reactors.

88-37 Flow Blockage of Cooling 6/14/88 All holders of OLs

Water to Safety System or CPs for nuclear

Components power reactors.

88-36 Possible Sudden Loss of RCS 6/8/88 All holders of OLs

Inventory During Low Coolant or CPs for PWRs.

Level Operation

88-35 Inadequate Licensee Performed 6/3/88 All holders of OLs

Vendor Audits or CPs for nuclear

power reactors.

88-34 Nuclear Material Control 5/31/88 All holders of OLs

and Accountability of or CPs for nuclear

Non-Fuel. Special Nuclear power reactors.

Material at Power Reactors

OL = Operating License

CP = Construction Permit

IN 88-44 June 24, 1988 believes that the coils burned out as a result of mechanical binding between

the lever and the edge of the breaker casing window. The licensee physically

inspected and electrically tested 28 other DS-416 breakers installed in Unit 1 and 18 breakers installed in Unit 2 as of June 16, 1988, and identified 10

additional cases where the lever and the edge of the breaker casing window were

making contact.

Although the root cause of the binding has not been determined, the licensee

has taken several steps to alleviate the problem. The licensee has replaced

the SRD in the STP-1 breakers that indicated signs of possible binding and has

verified that the clearances between the lever and the casing are sufficient to

preclude further binding. In addition, the licensee has extensively briefed

the STP control room personnel on this binding problem. It should be noted

that although the SRD may bind, it is still possible to manually trip the

breaker closing springs by pushing the "CLOSE" button located at the circuit

breaker.

The licensee has contacted Westinghouse for assistance in determining the root

cause of the binding. The NRC will remain cognizant of any new developments

and await the results of the South Texas and Westinghouse investigation. The

NRC will issue a further generic communication if warranted by the availability

of additional information or if additional regulatory action is deemed necessary.

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

If you have any questions about this matter, please contact one of the techni- cal contacts 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: Kamal Naidu, NRR

(301) 492-0980

Jaime Guillen, NRR

(301) 492-1170

Attachment: List of Recently Issued NRC Information Notices

• SEE PREVIOUS PAGE FOR CONCURRENCE

• OGCB:DOEA:NRR *RPM:ARM *C:OGCG:DOEA:NRR

JGuillen TechEd CHBerlinger

06/20/88 6/20/88 6/20/88

IN 88-XX

June xx, 1988 between the lever and the edge of the breaker casing window. The STP licensee

physically inspected and electrically tested 28 other DS-416 breakers installed

in Unit 1 and 18 breakers installed in Unit 2 as of June 16, 1988, and identi- fied ten additional cases where the lever and the edge of the breaker casing

window were making contact.

Although the licensee has not determined the root cause of the binding, it has

taken several steps to alleviate the problem. The licensee has replaced the

SRD in the STP-1 breakers that indicated signs of possible binding and has

verified that the clearances between the flapper and the housing are sufficient

to preclude further binding. In addition, the licensee has extensively briefed

the STP control room personnel on this binding problem. It should be noted

that although the SRD may bind, it is still possible to manually trip the

breaker closing springs.

The licensee has contacted Westinghouse for assistance in determining the root

cause of the binding. The NRC will remain cognizant of any new developments

and await the results of the South Texas and Westinghouse investigation. The

NRC will issue further generic communication if a determination is made that

this binding is a generic problem and that regulatory action is required.

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

If you have any questions about this matter, please contact one of the techni- cal contacts 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: Kamal Naidu, NRR

(301) 492-0980

Jaime Guillen, NRR

(301) 492-1170

Attachment: List of Recently Issued NRC Information Notices

D/DOEA:NRR C/OGB: ANRR

CERossi CHBerlinger

06/ /88 06/ia/88 OGC EA:NRR R B:DRIS:NRR CkRYI:DRIS:NRR AD/DRIS:NRR RPB:ARM

JGu len KNa iB h BXG-rffes TechEdol

06/2A/88 06// 88 06v 8 0/ 06/20/88