IE Circular No. 80-23, Potential Defects in Beloit Power Systems Emergency Generators

                                                           SSINS No.: 6830 
                                                           Accession No.: 
                                                           IEC 80-23      

                                UNITED STATES
                           WASHINGTON, D. C. 20555
                              October 31, 1980



This circular addresses a potential deficiency involving the field leads of 
generators manufactured by Beloit Power systems. It is known that the 
subject generators have been coupled with Fairbanks Morse diesel engines for 
use in nuclear power facilities; however, it is not known whether they have 
been coupled with other diesel engines for such use. Accordingly, the intent 
of this circular is to notify all nuclear power facilities of the potential 
defect and to assure that appropriate remedial actions are taken, if needed.

The Nuclear Regulatory Commission was first informed of the potential defect
by a phone call from Mr. R. H. Beadle of the Fairbanks Morse Engine Division
of Colt Industries to Mr. D. W. Hayes of Region III on September 19, 1980. 
On September 20, 1980, a conference call was held between the NRC Duty 
Officer, personnel from Prairie Island Nuclear Power Station, Mr. Beadle of 
Fairbanks Morse, and Mr. C. Evenson of Beloit Power Systems, the principal 
spokesman. The purpose of this call was to describe an inspection method 
which Prairie Island personnel could use to examine the field lead 
assemblies of their generators for the potential defect. (We have since been 
informed by the Resident Inspector that the field lead assemblies of the 
Prairie Island generators did not have the suspected defects.) 

In order to disseminate this information on a timely basis, the NRC Duty 
Officer at Bethesda called those operating facilities which he knew were 
using the suspect generators on September 20 and 21, 1980. The information 
conveyed included a description of the potential defect and a description of
the aforementioned inspection method. The operating facilities called were: 

               FACILITY                      NO. OF UNITS

          Calvert Cliffs 1 and 2                  3
          Crystal River 3                         2 
          Hatch 1 and 2                           5 
          Duane Arnold                            2 
          North Anna 1 and 2                      4
          Millstone 1 and 2                       3 
          Robinson 2                              2 
          Prairie Island                          2 
          Vermont Yankee                          2 
          Peach Bottom 2 and 3                    4 
          Arkansas Nuclear One, Unit 2            2

                                                          IEC 80-23       
                                                          October 31, 1980 
                                                          Page 2 of 3     

These phone calls were subsequently followed up with a Part 21 Report dated 
September 22, 1980 from Mr. J. M. Moriarty, Manager, Utility Sales, 
Fairbanks Morse Engine Division. Information conveyed in the Part 21 Report 
included the following excerpt 

     "A Beloit Power Systems generator in commercial service at Sitka, 
     Alaska lost its field because a lead between the collector rings and 
     the field coils shorted to the rotor and burned in two pieces at the 
     point of the short. Subsequent examination of another generator of 
     identical design at the same installation showed frayed insulation at a 
     clamp (same location as the burn through) which secures the lead to the 
     rotor. This unit was operating satisfactorily but if the insulation 
     damage were to progress the possibility of grounding the lead to the 
     rotor exists." 

     "To determine if the problem might exist at other locations our chief 
     electrical engineer was sent to Provo, Utah which has four generators 
     of identical design. He has reported by phone that two of the four at 
     Provo have frayed insulation at the clamp but that there was no 
     indication of loss of field." 

     "Concurrent with, our inspection at Provo, Beloit Power Systems was 
     asked to evaluate the cause of frayed insulation and also if any other 
     generators might have the same problem. Their verbal report to us is 
     that the cause of fraying is poor workmanship in installation of the 
     clamps and that there are other generators of identical design in this 
     area. Specifically the eight generators shipped to Limerick 
     (Philadelphia Electric) are of the identical design in the area where 
     poor workmanship is known to have caused a problem." 

     "Our plan is to inspect the Limerick generators and repair any poor 
     workmanship which may be found. Beloit Power Systems also reports 
     verbally that the design in this area for 5 and 6 frame alternators has
     been similar for a number of years and it is therefore possible that 
     the problem may extend to operating units." 


1.   Determine whether or not your facility uses emergency generators 
     manufactured by Beloit Power Systems, having frame sizes 5 or 6, as 
     part of the onsite emergency power system; if not, you need not pursue 
     this matter further. 

2.   If your facility uses generators manufactured by Beloit Power Systems 
     you should inspect the connections between the collector rings and the 
     field coils in the field lead assemblies of the generators for frayed 
     insulation at the clamps and make needed repairs per the enclosed 
     instruction sheet, "Inspection Procedures for Generator Field Leads". 
     The inspections should be completed as soon as practical and conducted 
     within the constraints of the Technical Specifications. 

3.   If the inspection reveals the need for repair or dressing of the leads,
     said repair should be initiated at operating facilities as soon as 
     practicable after the need has been determined but no later than ten 
     (10) days thereafter, provided the unit is capable of performing its 

                                                          IEC 80-23       
                                                          October 31, 1980 
                                                          Page 3 of 3     

     without the repair. Otherwise, the repair should be initiated 
     immediately after the need has been identified. Needed repair work 
     should be coordinated with Beloit Power Systems as stated in the 
     inspection procedure. 

4.   If the inspection reveals the need for repair or dressing of leads at 
     facilities holding Construction Permits, said repair should be 
     initiated at the licensee's earliest convenience and coordinated with 
     Beloit Power Systems. 

"Inspection Procedure for
  Generator Field Leads"


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