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 L NRC/IE
To:
References
IN-86-026, NUDOCS 8604150542
Download: ML031220661 (5)

SSINS No.: 6835IN 86-26UNITED STATESNUCLEAR REGULATORY COMMISSIONOFFICE OF INSPECTION AND ENFORCEMENTWASHINGTON, D.C. 20555April 17, 1986INFORMATION NOTICE NO. 86-26: POTENT1AL PROBLEMS IN GENERATORS MANUFACTUREDBY ELECTRICAL PRODUCTS INCORPORATED

Addressees

All nuclear power reactor facilities holding an operating license (OL) or aconstruction permit (CP).

Purpose

This notice is to alert recipients to a potentially significant problem involvingthe failure of Electrical Products Incorporated (EPI) diesel generators withoutprior warning during an emergency demand. Actions taken by licensees to preventrecurrence also are discussed. It is expected that recipients will review thisinformation for applicability to their facilities and consider actions, ifappropriate, to preclude a similar problem occurring at their facilities.However, suggestions-contained in this information notice do not constitute NRCrequirements; therefore, no specific action or written response is required.

Description of Circumstances

Washington Public Power Supply System (WPPSS) Unit 2On July 21, 1983, emergency diesel generator (DG) 1A had high vibration levelreadings accompanied by sparks from the rotor shaft bearing area. Upon disas-sembly it was determined that a shim, required to maintain clearance at thethrust bearing, was missing. Inspection of DG 1B showed that the same shim wasmissing. The two generators were returned to EPI (Cleveland, Ohio) where themissing shim was installed and the damaged areas refurbished. The originaldesign, which placed electrical insulation between the rotor shaft and theslip-ring end bearing inner race, was maintained.On July 9, 1984, during monthly surveillance testing, a high vibration alarmwas observed on emergency DG 1B. Investigation after completion of the 4-hourtest revealed that the slip-ring end bearing had turned on the shaft insulationdestroying 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 bearingwas mounted directly on the shaft. The bearing housing was insulated to providethe required electrical insulation. No failure has-been reported since thereported test failure in July 1984.8604150542

• IN 86-26April 17. 19v6 Grand Gulf Unit 1 K>At Grand Gulf Unit 1, the high pressure core spray pump is powered by a dedicateuDG. On July 13, 1985, during surveillance testing, the generator failed and wasobserved to be emitting sparks. Power Systems Division (PSD) of Morrison Knudsen,the supplier of the DG unit, determined that the electrical insulation betweenthe inner race of the cylindrical roller bearing at the slip-ring end and therotor shaft had degraded. The degradation allowed the shaft to drop down andrub the inner and outer oil seals causing the sparks. EPI and PSD have developeda procedure to implement the same design modification at Grand Gulf as usedpreviously at WPPSS.Watts Bar Unit 2On June 10, 1983, during the performance of a test, the generator shaft wasobserved to be rubbing against the inner and outer oil seals at the slip-ringend. Examination after disassembly revealed that the thickness of the oilthrower was less than specified, causing a mismatch between the inner and outerraces of the slip-ring end bearing that resulted in the inner race breakingloose 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 correctthe alignment, adding a shim to restrain the outer race, and installing newbearings. TVA inspected four other generators and made similar modifications.Background:The failures occurred in electrical generators manufactured at EPI located inCleveland, Ohio. EPI was a division of Portec from 1969-1979. In 1979, Portecsold EPI to Northern Electrical Industries-Parsons Peebles (NEI-Peebles) ofGreat Britain. The manufacturing operations at Cleveland ceased in the Fall of1984. 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 tandemdiesel engine configurations. Installation of the insulation between the rotorshaft and the bearing also is used for single engine applications and in somecases it is installed under the shaft bearing at the other end of the generatoras well. The purpose of the insulation (3M Scotchply brand, type 1009, glass/epoxycomposite tape) is to prevent circulating currents through the generator shaft.This insulation method was limited by EPI to 8-pole 900-rpm machines. Theinitiating failure mechanism of the insulation has been attributed by varioussources to insulation creep fatigue, misalignment of the engines, poor insulationworkmanship, or inadequate original design. The first WPPSS and the Watts Barfailures appear-to be isolated cases of improperly machined pieces; however, thefailures manifest themselves in a similar manner and may be discovered during thechecks for insulation damage.

IN 86-26April 17, 1986 PSD has stated that a procedure to monitor shaft movement will have to be specificfor each plant because of design differences that impact the allowable movementand the jacking force. Jacking the shaft up and down and recording the movementwill determine the vertical play between the shaft and bearing housing, out careshould be taken to use a load cell or circle force gauge between the jack andthe generator shaft to prevent damage.Other suppliers that have used EPI generators include Stewart & Stevenson, Alcoand Bruce GM (EMD). See Attachment 1 for a list of facilities identified oyEPI and PSD as recipients of the subject generators. Some of the generatorsnave 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 naveany questions regarding this notice, please contact the Regional Aaministratorof the appropriate NRC regional office or this office.X\visli/fEdward L ordan, DirectorDivisior of Emergency Preparednessand Engineering ResponseOffice of Inspection and EnforcementTecnnical Contacts: James C. Stewart, IE(301) 492-9061K.R. Naidu, IE(301) 492-4179Attachments:I. List of EPI 900 RPM Generators2. List of Recently Issued IE Information Notices

Attachment 1IN 86-26April 17, 1986 Domestic EPI 900 RPM GeneratorsCustomer/SiteNo. UnitsD/G SupplierArkansas P&L/Nuclear 1Boston Edison/Pilgrim 1Duke Power/OconeeFlorida P&L/St. LucieHouston L&P/Allens CreekJersey Central P&L/Oyster CreekMississippi P&L/Grand GulfMississippi P&L/Grand GulfNew York State PowerAuthority/FitzPatrickPacific G&E/Diablo CanyonPortland G&E/TrojanPublic Service of Oklahoma/Black FoxPuget Sound/SkaggitSMUD/Rancho SecoTVA/Hartsville, Phipps BendTVA/SequayahTVA/SequayahTVA/Watts BarVepco/North AnnaWPPSS/Hanford 122121222452212641642(See Note 1)(See Note 2)(See Note 3)(See Note 4)Stewart & StevensonALCOPSDPSDPSDPSDPSDBruce GM (EMD)Bruce GM (EMD)ALCOPSDPSDPSDBruce GM (EMD)PSDBruce GM (EMD)PSDPSDStewart & StevensonStewart & StevensonNotes: 1. Generator returned to PSD2. Obtained from TVA3. One unit sent to foreign plant, one unit spare4. Two units to Oyster Creek, three units sent to foreign plants,one unit sent to NASA

Attachnient 2IIN 86-26April 17, 1986LIST OF RECENTLY ISSUEDIE INFORMATION NOTICESInformation Date ofNotice No. Subject Issue __Issued to-86-25Traceability And MaterialControl Of Material AndEquipment, ParticularlyFasteners4/11/8686-24Respirator Users Notice: 4/11/86Increased Inspection FrequencyFor Certain Self-ContainedBreathing Apparatus AirCylinders86-2386-2286-21Excessive Skin Exposures DueTo Contamination With HotParticlesUnderresponse Of RaditionSurvey Instrument To HighRadiation FieldsRecognition Of AmericanSociety Of MechanicalEngineers AccreditationProgram For N Stamp HoldersLow-Level Radioactive WasteScaling Factors, 10 CFRPart 61Reactor Coolant Pump ShaftFailure At Crystal RiverNRC On-Scene Response DuringA Major Emergency4/9/863/31/863/31/863/28/863/21/863/26/86All power reactorfacilities holdingan OL or CPAll power reactorfacilities holdingan OL or CP; researchand test reactorfacilities; fuelcycle licensees andPriority 1 materiallicenseesAll power reactorfacilities holdingan OL or CPAll power reactorfacilities holdingan OL or CP andresearch and testreactorsAll power reactorfacilities holdingan OL or CP and allrecipients of NUREG-0040 (white book)All power reactorfacilities holdingan OL or CPAll power reactorfacilities holdingan OL or CPAll power reactorfacilities holdingan OL or CP86-2086-1986-18OL = Operating LicenseCP = Construction Permit