Information Notice 1987-12, Potential Problems with Metal Clad Circuit Breakers, General Electric Type AKF-2-25

Potential Problems with Metal Clad Circuit Breakers, General Electric Type AKF-2-25

ML031140523
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, Skagit, Marble Hill
Issue date:	02/13/1987
From:	Jordan E NRC/IE
To:
References
IN-87-012, NUDOCS 8702110132
Download: ML031140523 (7)

SSINS No.: 6835 IN 87-12 UNITED STATES

NUCLEAR REGULATORY COMMISSION

OFFICE OF INSPECTION AND ENFORCEMENT

WASHINGTON, D.C. 20555 February 13, 1987 IE INFORMATION NOTICE 87-12: POTENTIAL PROBLEMS WITH METAL CLAD CIRCUIT

BREAKERS, GENERAL ELECTRIC TYPE AKF-2-25

Addressees

All nuclear power reactor facilities holding an operating license or a

construction permit.

Purpose

This notice is to alert recipients of potential problems with the General

Electric Company (GE) AKF-2-25 type circuit breakers failing to fully open on

demand. It is expected that recipients will review the information for

applicability to their facilities and consider actions, if appropriate, to

preclude 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

1. Pilgrim Nuclear Power Station

On June 29, 1986, the "AA" recirculation pump (RP) motor/generator (MG)

set field breaker (AKF-2-25) failed to trip while the MG was being removed

from service. Licensee investigation revealed that the breaker was

mechanically bound and could not be actuated by rotating the trip shaft.

Because the breaker had not fully opened, the breaker auxiliary switch

"alt contact, which is in series with the shunt trip coil (STC), did not

open the circuit to the STC, which then burned out. Improper lubrication

and misadjustment appeared to be the cause of binding.

On March 15, 1985, the turbine generator field breaker (AKF-2-25) failed

to open when it received a trip signal from its manual control switch.

Examination determined that there was insufficient lubrication on the

link and cam of the centerpole of the breaker and that the eccentric cam

bushing was improperly Installed.

On February 9, 1985, the "A" RP MG-set field breaker (AKF-2-25) failed

to open on demand after the "A" RP motor tripped. The control/ATWS STC

was observed to be burned and open circuited. Additionally, the auxiliary

switch that was connected to the breaker trip shaft was found to have

loose mounting bolts and to be damaged. The licensee determined that

mechanical binding and/or auxiliary switch problems caused the failure of

the breaker to trip on demand.

870

IN 87-12 February 13, 1987 On April 3, 1983, the "B" RP MG-set field breaker (AKF-2-25) failed to

open; consequently, the STC burned out when the "B" RP was secured by the

control room operators. The licensee maintenance personnel found

mechanical binding of the breaker unit, which required partial disassembly

to free the breaker. The licensee determined that the shunt trip device

rotated the trip shaft, thereby starting the trip action; however, the

cam arrangement failed to complete its intended action and the trip action

was interrupted.

2. Dresden Unit 3 On September 2, 1983, personnel could not open the "B" RP MG-set

field breaker (AKF-2-25) and found the STC burned out. The STC was

replaced and the breaker was cleaned and lubricated.

On March 1, 1982, while performing the ATWS surveillance, which requires

tripping and reclosing the field breaker, the plant personnel found the

field breaker inoperable. Plant personnel investigated and found the

operator arm disconnected from the auxiliary contacts. The arm was

reconnected and the surveillance was performed.

Discussion:

On February 21, 1980, the NRC issued an order requiring the installation of an

ATWS RP trip function. Some licensees installed a second STC on the two RP

MG-set field breakers and the necessary instrumentation/logic to cause a breaker

trip when certain parameters are sensed. Pilgrim and Dresden have this

arrangement. Other licensees installed the ATWS trip coils in the 4.16 kV/6.9 kV

circuit breakers that supply power to the two MG-sets.

The AKF-2-25 circuit breaker is a field switch without overcurrent protection.

It is a three-pole breaker with the center pole modified specifically to serve

as a dc switch. In the ATWS RP trip function application, the AKF-2-25 field

breaker is equipped with two STCs, one of which is dedicated to respond to an

ATWS demand. Each STC is energized through a normally open "A" contact that

is controlled by the breaker's moving contacts. The "A" contact is an auxiliary

switch that opens when the breaker is fully open and closes when the breaker

is closed (ON position). The "A" contact is in series with the STC. Thus, when the breaker is closed, the "A" contact is closed and the STC is ready to

trip on receipt of a signal from the control room or the ATWS logic. The STC

is not rated for continuous duty and will overheat and fail if subjected to

full voltage for more than a few seconds. If a breaker does not fully open

when demanded by an STC, the "A" contact will not open and the STC will

overheat and fail. Therefore, if a subsequent ATWS trip signal is initiated, the safety function will not be performed. An STC failure can only be detected

by testing; remote indication is not provided.

IN 87-12 February 13, 1987 The most recent breaker failure at Pilgrim has been attributed to improper

maintenance performed by GE service technicians, who at the time were unaware

of special maintenance practices developed by the GE Atlanta Service Shop.

The GE Atlanta facility disassembled the failed breaker and discovered that it

was out of adjustment and that improper lubricants had apparently been used.

GE has issued Service Information Letter Number 448 to address special

maintenance practices developed for the entire AK type breaker series which

includes AK, AKU, AKF, and AKR type circuit breakers.

The ATWS trip function is required by 10 CFR 50.62(c)(5) and specific quality

assurance guidance has been provided for non-safety-related ATWS equipment

(NRC Generic Letter 85-06 dated April 16, 1985).

The GE AKF type circuit breakers have been shown to be susceptible to failure

as a result of binding within the breaker cam mechanism, unless proper

maintenance procedures are developed and followed by individuals trained

specifically to service the AKF breaker. GE has suggested that the following

maintenance information be incorporated into licensee programs for GE AKF-type

circuit breakers:

(1) Maintenance/inspection intervals of every 12 months or at each refueling

outage. A complete breaker overhaul every 5 years is recommended to

complement the annual cyclical maintenance.

(2) Only specified lubricants should be used on these circuit breakers. Molykote

BR2 Plus grease or equivalent for the slot in the circuit breaker center- pole cam-link and GE Specification D50HD38 (Mobil 28) for all other

applications. The grease of GE Specifications D50H15 and D50H47 is no

longer recommended for this breaker.

NOTE: D50HD38 lubricant should not be mixed with D50H15 and D50H47 Tiibiicants. Before changing to D50HD38 lubricant, maintenance personnel

should clean the circuit breaker thoroughly to remove all D50H15 and

D50H47 lubricant from the circuit breaker.

(3) Because of the complexity and difficulty in properly making crucial

adjustments unique to GE AKF type circuit breakers, only qualified, properly trained personnel should perform these maintenance activities.

(4) For type AKF circuit breakers which have not yet been converted to D50HD38 lubricant, cycle the breakers a few times between maintenance and inspec- tion events whenever plant conditions allow.

IN 87-XX

February XX, 1987 If you have

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

any questions regarding this matter, please contact the Regional

of the appropriate regional office or this office.

Edward L. Jordan, Director

Division of Emergency Preparedness

and Engineering Response

Office of Inspection and Enforcement

Technical Contacts: K. R. Naidu, IE

(301) 492-4179 J. Jacobson, IE

(301) 492-8845 Attachment: List of Recently Issued Information Notices

PREVIOUS CONCURRENCES TECH ED/IE

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Attachment 1 IN 87-12 February 13, 1987 LIST OF RECENTLY ISSUED

IE INFORMATION NOTICES

Information Date of

Notice No. Subject Issue Issued to

87-11 Enclosure of Vital Equipment 2/13/87 All power reactor

Within Designated Vital facilities holding

Areas an OL or CP

87-10 Potential for Water Hammer 2/11/87 All BWR facilities

During Restart of Residual holding an OL or CP

Heat Removal Pumps

87-09 Emergency Diesel Generator 2/5/87 All power reactor

Room Cooling Design facilities holding

Deficiency an OL or CP

87-08 Degraded Motor Leads in 2/4/87 All power reactor

Limitorque CD Motor facilities holding

Operators an OL or CP

87-07 Quality Control of Onsite 2/3/87 All power reactor

Dewatering/Solidification facilities holding

Operations by Outside an OL or CP

Contractors

87-06 Loss of Suction to Low- 1/30/87 All power reactor

Pressure Service Water facilities holding

System Pumps Resulting From an OL or CP

Loss of Siphon

87-05 Miswiring in a Westinghouse 2/2/87 All Westinghouse

Rod Control System power reactor

facilities holding

an OL or CP

87-04 Diesel Generator Fails 1/16/87 All power reactor

Test Because of Degraded facilities holding

Fuel an OL or CP

87-03 Segregation of Hazardous 1/15/87 All NRC licensees

87-02 Inadequate Seismic Quali- 1/15/87 All power reactor

fication of Diaphragm facilities holding

Valves by Mathematical an OL or CP

Modeling and Analysis

OL = Operating License

CP = Construction Permit

IN 87-XX

January XX, 1987 If you have

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

matter, please contact

any questions regarding this nffice the Regional

9 +k. ann"^n".2ta raninnal or this office.

Edward L. Jordan, Director

Division of Emergency Prepar dness

and Engineering Response

Office of Inspection and nforcement

Technical Contacts: K. R. Naidu, IE

(301) 492-4179 J. Jacobson, IE

(301) 492-8845 Attachment: List of Recently Issued Informatin Notices

• SEE PREV US CONCURRENCES

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12/12/86 12/16/86 12/19/86 / /87 12/23/86 B EPER D/DIR/DEPER DIR/DEPER

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IN 86-XX

December XX, 1986 No specific action or written response is required by this notice. If you have

any questions regarding this matter, please contact the Regional Administrator

of the appropriate regional office or this office.

E ar . Jordan, Director

vision of Emergency Preparedness

and Engineering Response

Office of Inspection and Enforcement

Technical Contacts: K. R.

(301)

Attachment:

List of Recently Is Notices

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RHeishman H ~er DGable

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