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

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 and was observed to be emitting sparks. Power Systems Division (PSD) of Morrison Knudsen, the supplier of the DG unit, determined

that the electrical

insulation

between the inner race of the cylindrical

roller bearing at the slip-ring

end and the rotor shaft had degraded.

The degradation

allowed the shaft to drop down and rub the inner and outer oil seals causing the sparks. EPI and PSD have developed a procedure

to implement

the same design modification

at Grand Gulf as used previously

at WPPSS.Watts Bar Unit 2 On June 10, 1983, during the performance

of a test, the generator

shaft was observed to be rubbing against the inner and outer oil seals at the slip-ring end. Examination

after disassembly

revealed that the thickness

of the oil thrower was less than specified, causing a mismatch between the inner and outer races of the slip-ring

end bearing that resulted in the inner race breaking loose and turning on the underlying

electrical

insulation.

The repairs at a Tennessee

Valley Authority (TVA) workshop consisted

of rebuil-ding oil seals, polishing

the shaft under the oil seals, replacing

the insula-tion material under the bearing, machining

the bearing housing cap to correct the alignment, adding a shim to restrain the outer race, and installing

new bearings.

TVA inspected

four other generators

and made similar modifications.

Background:

The failures occurred in electrical

generators

manufactured

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

In 1979, Portec sold EPI to Northern Electrical

Industries-Parsons

Peebles (NEI-Peebles)

of Great Britain. The manufacturing

operations

at Cleveland

ceased in the Fall of 1984. Currently, EPI furnishes

spare parts and modifications

to existing units.Discussion:

The failures described

above have all occurred at the slip-ring

end of the tandem diesel engine configurations.

Installation

of the insulation

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

and in some cases it is installed

under the shaft bearing at the other end of the generator as well. The purpose of the insulation

(3M Scotchply

brand, type 1009, glass/epoxy

composite

tape) is to prevent circulating

currents through the generator

shaft.This insulation

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

The initiating

failure mechanism

of the insulation

has been attributed

by various sources to insulation

creep fatigue, misalignment

of the engines, poor insulation

workmanship, or inadequate

original design. The first WPPSS and the Watts Bar failures appear-to

be isolated cases of improperly

machined pieces; however, the failures manifest themselves

in a similar manner and may be discovered

during the checks for insulation

damage.

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 Boston Edison/Pilgrim

1 Duke Power/Oconee

Florida P&L/St. Lucie Houston L&P/Allens

Creek Jersey Central P&L/Oyster

Creek Mississippi

P&L/Grand

Gulf Mississippi

P&L/Grand

Gulf New York State Power Authority/FitzPatrick

Pacific G&E/Diablo

Canyon Portland G&E/Trojan

Public Service of Oklahoma/Black

Fox Puget Sound/Skaggit

SMUD/Rancho

Seco TVA/Hartsville, Phipps Bend TVA/Sequayah

TVA/Sequayah

TVA/Watts

Bar Vepco/North

Anna WPPSS/Hanford

1 2 2 1 2 1 2 2 2 4 5 2 2 1 2 6 4 1 6 4 2 (See Note 1)(See Note 2)(See Note 3)(See Note 4)Stewart & Stevenson ALCO PSD PSD PSD PSD PSD Bruce GM (EMD)Bruce GM (EMD)ALCO PSD PSD PSD Bruce GM (EMD)PSD Bruce GM (EMD)PSD PSD Stewart & Stevenson 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 Control Of Material And Equipment, Particularly

Fasteners 4/11/86 86-24 Respirator

Users Notice: 4/11/86 Increased

Inspection

Frequency For Certain Self-Contained

Breathing

Apparatus

Air Cylinders 86-23 86-22 86-21 Excessive

Skin Exposures

Due To Contamination

With Hot Particles Underresponse

Of Radition Survey Instrument

To High Radiation

Fields Recognition

Of American Society Of Mechanical

Engineers

Accreditation

Program For N Stamp Holders Low-Level

Radioactive

Waste Scaling Factors, 10 CFR Part 61 Reactor Coolant Pump Shaft Failure At Crystal River NRC On-Scene Response During A Major Emergency 4/9/86 3/31/86 3/31/86 3/28/86 3/21/86 3/26/86 All power reactor facilities

holding an OL or CP All power reactor facilities

holding an OL or CP; research and test reactor facilities;

fuel cycle licensees

and Priority 1 material licensees All power reactor facilities

holding an OL or CP All power reactor facilities

holding an OL or CP and research and test reactors All power reactor facilities

holding an OL or CP and all recipients

of NUREG-0040 (white book)All power reactor facilities

holding an OL or CP All power reactor facilities

holding an OL or CP All power reactor facilities

holding an OL or CP 86-20 86-19 86-18 OL = Operating

License CP = Construction

Permit