Information Notice 1994-51, Inappropriate Greasing of Double Shielded Motor Bearings

Inappropriate Greasing of Double Shielded Motor Bearings

ML031060599
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, Fort Saint Vrain, Shoreham, Satsop, Trojan, Atlantic Nuclear Power Plant
Issue date:	07/15/1994
From:	Grimes B Office of Nuclear Reactor Regulation
To:
References
IN-94-051, NUDOCS 9407080037
Download: ML031060599 (22)

UNITED STATES

NUCLEAR REGULATORY COMMISSION

OFFICE OF NUCLEAR REACTOR REGULATION

WASHINGTON, D.C. 20555 July 15, 1994 NRC INFORMATION NOTICE 94-51: INAPPROPRIATE GREASING OF DOUBLE SHIELDED MOTOR

BEARINGS

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 potential for failure of safety-related

equipment as a result of inappropriate greasing of double shielded motor

bearings. 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

On January 20 and January 21, 1994, two different emergency diesel generator

fuel oil transfer pumps failed to start at the North Anna Power Station when

the motor breakers tripped on overload during testing. On January 22, 1994, the licensee tested the remaining six diesel fuel oil transfer pumps, and two

more of the pump motor breakers tripped on thermal overload. These two pumps

supply the same diesel generator. Consequently this diesel generator was

declared inoperable.

There are eight fuel oil transfer pumps at North Anna; two redundant pumps

supply each of the station four emergency diesel generators from underground

fuel oil storage tanks. The transfer pumps are located in an unheated

building near the fuel oil tanks. This building is continuously supplied with

outside air to reduce the oil fumes. As a result, the temperature in the

building was about the same as that of the outdoor air, which was abnormally

cold: -15°C [5°F]. The licensee installed temporary heaters in the building

and, after a short warmup period, successfully tested all of the transfer

pumps.

Discussion

The licensee investigation of the problem showed that the failures to start

the pumps were caused by excessive grease in the motor bearings, which became

very stiff at the abnormally low temperatures. This caused abnormally high

starting loads that prevented the motor from accelerating past the low

9407080037 6¢ 0 Po R I PE Note C( E C-os 5

IN 94-51 July 15, 1994 rotational speeds that cause the motor to draw high starting currents. The

sustained high starting currents caused the motor power supply breaker thermal

overload devices to trip.

This determination was confirmed by placing the motors in a freezer for

2.5 hours5.787037e-5 days <br />0.00139 hours <br />8.267196e-6 weeks <br />1.9025e-6 months <br /> at -14°C [6'F] and applying power to them. At this temperature

some of the motors drew 6 amperes when the rated 460 volts were applied to the

motor terminals, compared to the rated full load current of 0.75 amperes.

These motors continued to run at a slow speed in the start-up current range.

When tested at the same temperature after the bearings were replaced, the

motors ran at normal speed and drew only 0.4 amperes.

The motor bearings are of the double shielded type, which are supplied by

several different manufacturers, and normally require no greasing after they

are installed. However, station records showed that 7 of the 8 motors had

been greased every 18 months since 1986. The old bearings were found to be

completely full of grease. According to the bearing vendors, a high grease

content inside the bearing shields could not only cause high starting loads, but could also cause the bearing to overheat and solidify the grease under

normal operating conditions.

Related Generic Communications

NRC Information Notice 88-12, "Overgreasing of Motor Bearings," April 12,

1988.

NRC Information Notice 93-26 and Supplement 1, "Grease Solidification Causes

Molded-Case Circuit Breaker Failure To Close," April 7, 1993, and

January 31, 1994.

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.

ian K. Grimes, Director

Division of Operating Reactor Support

Office of Nuclear Reactor Regulation

Technical contact: Rick McWhorter, RII

(703) 894-5421 Attachment:

List of Recently Issued NRC Information Notices

4 Attachment

IN 94-51 July 15, 1994 LIST OF RECENTLY ISSUED

NRC INFORMATION NOTICES

Information Date of

Notice No. Subject Issuance Issued to

94-50 Failure of General 07/14/94 All holders of OLs or CPs

Electric Contactors for nuclear power reactors.

to Pull in at the

Required Voltage

94-49 Failure of Torque 07/06/94 All holders of OLs or CPs

Switch Roll Pins for nuclear power reactors.

94-48 Snubber Lubricant 06/30/94 All holders of OLs or CPs

Degradation in High- for nuclear power reactors.

Temperature Environments

94-13, Unanticipated and Unin- 06/28/94 All holders of OLs or CPs

Supp. 1 tended Movement of Fuel for nuclear power reactors.

Assemblies and other

Components due to Improper

Operation of Refueling

Equipment

94-47 Accuracy of Information 06/21/94 All U.S. Nuclear Regulatory

Provided to NRC during Commission Material

the Licensing Process Licensees.

94-46 NonConservative Reactor 06/20/94 All holders of OLs or CPs

Coolant System Leakage for nuclear power reactors.

Calculation

94-45 Potential Common-Mode 06/17/94 All holders of OLs or CPs

Failure Mechanism for for nuclear power reactors.

Large Vertical Pumps

94-44 Main Steam Isolation 06/16/94 All holders of OLs or CPs

Valve Failure to Close for nuclear power reactors.

on Demand because of

Inadequate Maintenance

and Testing

94-43 Determination of Primary- 06/10/94 All holders of OLs or CPs

to-Secondary Steam for pressurized water

Generator Leak Rate reactors.

OL = Operating License

CP = Construction Permit

Il

IN 94-51 July 15, 1994 rotational speeds that cause the motor to draw high starting currents. The

sustained high starting currents caused the motor power supply breaker thermal

overload devices to trip.

This determination was confirmed by placing the motors in a freezer for

2.5 hours5.787037e-5 days <br />0.00139 hours <br />8.267196e-6 weeks <br />1.9025e-6 months <br /> at -14°C [6°F] and applying power to them. At this temperature

some of the motors drew 6 amperes when the rated 460 volts were applied to the

motor terminals, compared to the rated full load current of 0.75 amperes.

These motors continued to run at a slow speed in the start-up current range.

When tested at the same temperature after the bearings were replaced, the

motors ran at normal speed and drew only 0.4 amperes.

The motor bearings are of the double shielded type, which are supplied by

several different manufacturers, and normally require no greasing after they

are installed. However, station records showed that 7 of the 8 motors had

been greased every 18 months since 1986. The old bearings were found to be

completely full of grease. According to the bearing vendors, a high grease

content inside the bearing shields could not only cause high starting torques, but could also cause the bearing to overheat and solidify the grease.

Related Generic Communications

NRC Information Notice 88-12, "Overgreasing of Motor Bearings," April 12,

1988.

NRC Information Notice 93-26 and Supplement 1, "Grease Solidification Causes

Molded-Case Circuit Breaker Failure To Close," April 7, 1993, and

January 31, 1994.

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 appropiate Office of Nuclear

Reactor Regulation project manager. rin .ignid-f

Brian K.Glme

Brian K. Grimes, 1 lrrector

Division of Operating Reactor Support

Office of Nuclear Reactor Regulation

Technical contact: Rick McWhorter, R11

(703) 894-5421 Attachment:

List of Recently Issued NRC Information Notices

• See previous concurrence I

OFFICE *OGCB:DORS *TECH ED *C/EELB:DE *REGION II *REGION II

NAME DCKirkpatrick CHBerlinger RMcWhorter ABelisle

DATE 05/03/94 05/02/94 .0 $ 94 06/06/94 06/20/94 n I 0 i1 -

• RF(gTnN TI I *ACIOGCB:DORS I D:DdK<'/

JRJohnson RLDennig 0 v

06/20/94 06/20/94 07/f/94 DOCUMENT NAME: 94-51. IN

IN 94-xx

June xx, 1994 rotational speeds that cause the motor to draw high starting currents. The

sustained high starting currents caused the motor power supply breaker thermal

overload devices to trip.

This determination was confirmed by placing the motors in a freezer for

2.5 hours5.787037e-5 days <br />0.00139 hours <br />8.267196e-6 weeks <br />1.9025e-6 months <br /> at -140 C [60F] and applying power to them. At this temperature

some of the motors drew 6 amperes when the rated 460 volts were applied to the

motor terminals, compared to the rated full load current of 0.75 amperes.

These motors continued to run at a slow speed in the start-up current range.

When tested at the same temperature after the bearings were replaced, the

motors ran at normal speed and drew only 0.4 amperes.

The motor bearings are of the double shielded type, which are supplied by

several different manufacturers, and normally require no greasing after they

are installed. However, station records showed that seven of the eight motors

had been greased every 18 months since 1986. The old bearings were found to

be completely full of grease. According to the bearing vendors, a high grease

content inside the bearing shields could not only cause high starting torques, but could also cause the bearing to overheat and solidify the grease.

Related Generic Communications

NRC Information Notice 88-12, "Overgreasing of Motor Bearings," April 12,

1988.

NRC Information Notice 93-26 and Supplement 1, "Grease Solidification Causes

Molded-Case Circuit Breaker Failure To Close," April 7, 1993, and

January 31, 1994.

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: Rick McWhorter, RII

(703) 894-5421 Attachment:

List of Recently Issued NRC Information Notices

• See previous concurrence

I

OFFICE *OGCB:DORS *TECH ED *C/EELB:DE *REGION II *REGION II

NAME DCKirkpatrick CHBerlinger RMcWhorter ABelisle

DATE 05/03/94 I05/02/94 _05/26/94

= _

06/06/94 06/20/94

• REGION IT I *AC/OGCB:DORS I D:DORS

JRJohnson RLDennig I BKGrimes

06/20/94_ 06/20/94 1.

06/ /94 _J.

DOCUMENT NAME: GREASMTR.IN

IN 94-xx

June xx, 1994 rotational speeds that cause the motor to draw high starting currents. The

sustained high starting currents caused the motor power supply breakers

thermal overload devices to trip.

This determination was confirmed by placing the motors in a freezer for 2.5 hours5.787037e-5 days <br />0.00139 hours <br />8.267196e-6 weeks <br />1.9025e-6 months <br /> at -14'C [60F] and applying power to them. At this temperature some of

the motors drew 6 amperes, when the rated 460 volts were applied to the motor

terminals, compared to the rated full load current of 0.75 amperes. These

motors continued to run at a slow speed in the start-up current range. When

tested at the same temperature after the bearings were replaced, the motors

ran at normal speed and drew only 0.4 amperes.

The motor bearings are of the double shielded type, which are supplied by

several different manufacturers, and normally require no greasing after they

are installed. However, station records showed that seven of the eight motors

had been greased every 18 months since 1986. The old bearings were found to

be completely full of grease. According to the bearing vendors, a high grease

content inside the bearing shields could not only cause high starting torques, but could also cause the bearing to overheat and solidify the grease.

Related Generic Communications

NRC Information Notice 88-12, "Overgreasing of Motor Bearings," April 12,

1988.

NRC Information Notice 93-26 and Supplement 1, "Grease Solidification Causes

Molded-Case Circuit Breaker Failure To Close," April 7, 1993, and

January 31, 1994.

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: Rick McWhorter, RII

(703) 894-5421 Attachment:

List of Recently Issued NRC Information Notices

• See Drevious concurrence

OFFICE *OGCB:DORS *TECH ED *C/EELB:DE *REGION II *REGION II

NAME DCKirkpatrick CHBerlinger RMcWhorter ABelisle

DATE 1 05/03/94 j05/02/94 [05/26/94 06/06/94 j 06/20/94

• REGION II IA AD)DORS I D:DORS I

JRJohnson Rennig BKGrimes

06/20/94 061)0/94 06/ /94 DOCUMENT NAME: GREASMTR.IN

a . &

IN 94-xx

June xx, 1994 rotational speeds that cause the motor to draw high starting currents. The

sustained high starting currents caused the motor power supply breakers

thermal overload devices to trip.

This determination was confirmed by placing the motors in a freezer for 2.5 hours5.787037e-5 days <br />0.00139 hours <br />8.267196e-6 weeks <br />1.9025e-6 months <br /> at -140C [6*F] and applying power to them. At this temperature some of

the motors drew 6 amperes, when the rated 460 volts were applied to the motor

terminals, compared to the rated full load current of 0.75 amperes. These

motors continued to run at a slow speed in the start-up current range. When

tested at the same temperature after the bearings were replaced, the motors

ran at normal speed and drew only 0.4 amperes.

The motor bearings are of the double shielded type, which are supplied by

several different manufacturers, and normally require no greasing after they

are installed. However, station records showed that seven of the eight motors

had been greased every 18 months since 1986. The old bearings were found to

be completely full of grease. According to the bearing vendors, a high grease

content inside the bearing shields could not only cause high starting torques, but could also cause the bearing to overheat and solidify the grease.

Related Generic Communications

NRC Information Notice 88-12, "Overgreasing of Motor Bearings," April 12,

1988.

NRC Information Notice 93-26 and Supplement 1, "Grease Solidification Causes

Molded-Case Circuit Breaker Failure To Close," April 7, 1993, and

January 31, 1994.

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: Rick McWhorter, RII

(703) 894-5421 Attachment:

List of Recently Issued NRC Information Notices

• See Drevious

-a-----~ concurrence Ir

OFFICE *OGCB:DORS *TECH ED *C/EELB:DE REGION II lEWO. II l

NAME DCKirkpatrick CHBerlinger ort

DATE 05/03/94 05/02/94 05/26/94 f6/e494 6/9X 94 I

.REGION IL_. LAC/OGCB:DORS I D:DORS

Johnson RJKiessel BKGrimes

06,)C/94 _061 /94 06/ /94 NAE

DOUMN NAME: GREASMIR..IN_

DOCUMENT GREASMTR.IN

I .

v sio ~IN 94-xx

May xx, 1994 6.0 amps of current, compared to the name plate rating of 0.75 amps, and ran at

a speed that was slower than normal. When tested at the same temperature after

the bearings were replaced, the motors drew only 0.4 amps and ran at normal

speed.

• mnt rs arc Westinghouse Model TBEP, Stylo 7.ZA 5C5G, 1/2 horscpower motrs.

ehsy on 460 volts ac at 3525 rpm The motor bearings are of the double

opcrate

shielded type, which are supplied by several different manufacturers, and

normally require no greasing after they are installed. However, station records

showed that seven of the eight motors had been greased every 18 months since

1986. The old bearings were found to be completely full of grease. According

to the bearing vendors, a high grease content inside the bearing shields could

not only cause high starting torques, but could also cause the bearing to

overheat and solidify the grease.

Related Generic Communications

NRC Information Notice 88-12, "Overgreasing of Motor Bearings," April 12, 1988.

NRC Information Notice 93-26 and Supplement 1, "Grease Solidification Causes

Molded-Case Circuit Breaker Failure To Close," April 7, 1993, and

January 31, 1994.

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(s): Rick McWhorter, RII

(703) 894-5421 Attachment:

List of Recently Issued NRC Information Notices

• See previous concurrence __l_X

OFFICE *OGCB:DORS *TECH ED C/EEL :DE REGION II REGION II

NAME DCKirkpatrick CHBerlinger IRMcWhorter MSinkule

DATE 05/03/94 05/02/94 05/&V/94 Q_ /94 _/4 l

IIl

REGION II I AC/OGCB:DORS I D:DORS

JRLJohnson A4ug<X eR/42BKGrimes

Of/ /94_ O/ 94 0f/ /94 DOCUMENT NAME: GREASMTR.IN

I . I

IN 94-xx

May xx, 1994 6.0 amps of current, compared to the name plate rating of 0.75 amps, and ran at

a speed that was slower than normal. When tested at the same temperature after

the bearings were replaced, the motors drew only 0.4 amps and ran at normal

speed.

These motors are Westinghouse Model TBEP, Style 72A35856, 1/2-horsepower motors.

They operate on 460 volts ac at 3525 rpm. The motor bearings are of the double

shielded type, which are supplied by several different manufacturers, and

normally require no greasing after they are installed. However, station records

showed that seven of the eight motors had been greased every 18 months since

1986. The old bearings were found to be completely full of grease. According

to the bearing vendors, a high grease content inside the bearing shields could

not only cause high starting torques, but could also cause the bearing to

overheat and solidify the grease.

Related Generic Communications

NRC Information Notice 88-12, "Overgreasing of Motor Bearings," April 12, 1988.

NRC Information Notice 93-26 and Supplement 1, "Grease Solidification Causes

Molded-Case Circuit Breaker Failure To Close," April 7, 1993, and

January 31, 1994.

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(s): Rick McWhorter, RII

(703) 894-5421 Attachment:

List of Recently Issued NRC Information Notices

• See previous concurrence

OFFICE OGCB:DORS TECH ED C/EELB:DE REGION II REGION II

NAME DCKirkpatrick CHBerlinger RMcWhorter MSinkule

DATE 05/-3/94

.

J 05 /

.

4 ,05/ /94

.

-05/ /94 05/ /94 REGION II IAC/OGCB:DORS I D:DORS

JRJohnson l BKGrimes

05/ /94 05/ /94 _ /94

_05/

DOCUMENT NAME: GREASMTR.IN