Information Notice 1986-26, Potential Problems in Generators Manufactured by Electrical Products Incorporated

Potential Problems in Generators Manufactured by Electrical Products Incorporated

ML031220661
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:	04/17/1986
From:	Jordan E NRC/IE
To:
References
IN-86-026, NUDOCS 8604150542
Download: ML031220661 (5)

SSINS No.: 6835 IN 86-26 UNITED STATES

NUCLEAR REGULATORY COMMISSION

OFFICE OF INSPECTION AND ENFORCEMENT

WASHINGTON, D.C. 20555 April 17, 1986 INFORMATION NOTICE NO. 86-26: POTENT1AL PROBLEMS IN GENERATORS MANUFACTURED

BY ELECTRICAL PRODUCTS INCORPORATED

Addressees

All nuclear power reactor facilities holding an operating license (OL) or a

construction permit (CP).

Purpose

This notice is to alert recipients to a potentially significant problem involving

the failure of Electrical Products Incorporated (EPI) diesel generators without

prior warning during an emergency demand. Actions taken by licensees to prevent

recurrence also are discussed. It is expected that recipients will review this

information for applicability to their facilities and consider actions, if

appropriate, to preclude a similar problem occurring at their facilities.

However, suggestions-contained in this information notice do not constitute NRC

requirements; therefore, no specific action or written response is required.

Description of Circumstances

Washington Public Power Supply System (WPPSS) Unit 2 On July 21, 1983, emergency diesel generator (DG) 1A had high vibration level

readings accompanied by sparks from the rotor shaft bearing area. Upon disas- sembly it was determined that a shim, required to maintain clearance at the

thrust bearing, was missing. Inspection of DG 1B showed that the same shim was

missing. The two generators were returned to EPI (Cleveland, Ohio) where the

missing shim was installed and the damaged areas refurbished. The original

design, which placed electrical insulation between the rotor shaft and the

slip-ring end bearing inner race, was maintained.

On July 9, 1984, during monthly surveillance testing, a high vibration alarm

was observed on emergency DG 1B. Investigation after completion of the 4-hour

test revealed that the slip-ring end bearing had turned on the shaft insulation

destroying the insulation. The reduction in insulation cross sectional thick- ness allowed the rotor shaft to drop slightly and rub on the bearing housing.

The corrective action employed after this failure was a design modification.

The insulation between the bearing and the shaft was removed and the bearing

was mounted directly on the shaft. The bearing housing was insulated to provide

the required electrical insulation. No failure has-been reported since the

reported test failure in July 1984.

8604150542

• IN 86-26 April 17. 19v6 Grand Gulf Unit 1 K>

At Grand Gulf Unit 1, the high pressure core spray pump is powered by

a dedicateu

DG. On July 13, 1985, during surveillance testing, the generator failed

observed to be emitting sparks. Power Systems Division (PSD) of Morrison and was

the supplier of the DG unit, determined that the electrical insulation Knudsen, the inner race of the cylindrical roller bearing at the slip-ring end between

rotor shaft had degraded. The degradation allowed the shaft to drop and the

rub the inner and outer oil seals causing the sparks. EPI and PSD down and

a procedure to implement the same design modification at Grand Gulf have developed

previously at WPPSS. as used

Watts Bar Unit 2 On June 10, 1983, during the performance of a test, the generator

observed to be rubbing against the inner and outer oil seals at theshaft was

end. Examination after disassembly revealed that the thickness of slip-ring

thrower was less than specified, causing a mismatch between the innerthe oil

races of the slip-ring end bearing that resulted in the inner race and outer

loose and turning on the underlying electrical insulation. breaking

The repairs at a Tennessee Valley Authority (TVA) workshop consisted

ding oil seals, polishing the shaft under the oil seals, replacing of rebuil- the

tion material under the bearing, machining the bearing housing cap to insula- the alignment, adding a shim to restrain the outer race, and installingcorrect

bearings. TVA inspected four other generators and made similar modifications.new

Background:

The failures occurred in electrical generators manufactured at EPI located

Cleveland, Ohio. EPI was a division of Portec from 1969-1979. In 1979, in

sold EPI to Northern Electrical Industries-Parsons Peebles (NEI-Peebles) Portec

Great Britain. The manufacturing operations at Cleveland ceased in of

the

1984. Currently, EPI furnishes spare parts and modifications to existing Fall of

units.

Discussion:

The failures described above have all occurred at the slip-ring end

diesel engine configurations. Installation of the insulation betweenof the tandem

the rotor

shaft and the bearing also is used for single engine applications and

cases it is installed under the shaft bearing at the other end of the in some

as well. The purpose of the insulation (3M Scotchply brand, type 1009,generator

composite tape) is to prevent circulating currents through the generator glass/epoxy

This insulation method was limited by EPI to 8-pole 900-rpm machines. shaft.

initiating failure mechanism of the insulation has been attributed by The

sources to insulation creep fatigue, misalignment of the engines, poor various

workmanship, or inadequate original design. The first WPPSS and the insulation

failures appear-to be isolated cases of improperly machined pieces; Watts Bar

however, the

failures manifest themselves in a similar manner and may be discovered

checks for insulation damage. during the

IN 86-26 April 17, 1986 PSD has stated that a procedure to monitor shaft movement will have to be specific

for each plant because of design differences that impact the allowable movement

and the jacking force. Jacking the shaft up and down and recording the movement

will determine the vertical play between the shaft and bearing housing, out care

should be taken to use a load cell or circle force gauge between the jack and

the generator shaft to prevent damage.

Other suppliers that have used EPI generators include Stewart & Stevenson, Alco

and Bruce GM (EMD). See Attachment 1 for a list of facilities identified oy

EPI and PSD as recipients of the subject generators. Some of the generators

nave been resold from the original customer or user and some have been cancelled;

therefore specific plant applications may be different than originally supplied.

No specific action or written response is required by this notice. If you nave

any questions regarding this notice, please contact the Regional Aaministrator

of the appropriate NRC regional office or this office.

X\visli/f

Edward L ordan, Director

Divisior of Emergency Preparedness

and Engineering Response

Office of Inspection and Enforcement

Tecnnical Contacts: James C. Stewart, IE

(301) 492-9061 K.R. Naidu, IE

(301) 492-4179 Attachments:

I. List of EPI 900 RPM Generators

2. List of Recently Issued IE Information Notices

Attachment 1 IN 86-26 April 17, 1986 Domestic EPI 900 RPM Generators

Customer/Site No. Units D/G Supplier

Arkansas P&L/Nuclear 1 2 Stewart & Stevenson

Boston Edison/Pilgrim 1 2 ALCO

Duke Power/Oconee 1 PSD

Florida P&L/St. Lucie 2 PSD

Houston L&P/Allens Creek 1 (See Note 1) PSD

Jersey Central P&L/Oyster Creek 2 (See Note 2) PSD

Mississippi P&L/Grand Gulf 2 PSD

Mississippi P&L/Grand Gulf 2 Bruce GM (EMD)

New York State Power 4 Bruce GM (EMD)

Authority/FitzPatrick

Pacific G&E/Diablo Canyon 5 ALCO

Portland G&E/Trojan 2 PSD

Public Service of Oklahoma/Black Fox 2 (See Note 3) PSD

Puget Sound/Skaggit 1 PSD

SMUD/Rancho Seco 2 Bruce GM (EMD)

TVA/Hartsville, Phipps Bend 6 (See Note 4) PSD

TVA/Sequayah 4 Bruce GM (EMD)

TVA/Sequayah 1 PSD

TVA/Watts Bar 6 PSD

Vepco/North Anna 4 Stewart & Stevenson

WPPSS/Hanford 1 2 Stewart & Stevenson

Notes: 1. Generator returned to PSD

2. Obtained from TVA

3. One unit sent to foreign plant, one unit spare

4. Two units to Oyster Creek, three units sent to foreign plants, one unit sent to NASA

Attachnient 2 IIN 86-26 April 17, 1986 LIST OF RECENTLY ISSUED

IE INFORMATION NOTICES

Information Date of

Notice No. Subject Issue __Issued to-

86-25 Traceability And Material 4/11/86 All power reactor

Control Of Material And facilities holding

Equipment, Particularly an OL or CP

Fasteners

86-24 Respirator Users Notice: 4/11/86 All power reactor

Increased Inspection Frequency facilities holding

For Certain Self-Contained an OL or CP; research

Breathing Apparatus Air and test reactor

Cylinders facilities; fuel

cycle licensees and

Priority 1 material

licensees

86-23 Excessive Skin Exposures Due 4/9/86 All power reactor

To Contamination With Hot facilities holding

Particles an OL or CP

86-22 Underresponse Of Radition 3/31/86 All power reactor

Survey Instrument To High facilities holding

Radiation Fields an OL or CP and

research and test

reactors

86-21 Recognition Of American 3/31/86 All power reactor

Society Of Mechanical facilities holding

Engineers Accreditation an OL or CP and all

Program For N Stamp Holders recipients of NUREG-

0040 (white book)

86-20 Low-Level Radioactive Waste 3/28/86 All power reactor

Scaling Factors, 10 CFR facilities holding

Part 61 an OL or CP

86-19 Reactor Coolant Pump Shaft 3/21/86 All power reactor

Failure At Crystal River facilities holding

an OL or CP

86-18 NRC On-Scene Response During 3/26/86 All power reactor

A Major Emergency facilities holding

an OL or CP

OL = Operating License

CP = Construction Permit