United States Nuclear Regulatory Commission - Protecting People and the Environment

ACCESSION #: 9707090142

                              Illinois Power Company

                              Clinton Power Station

                              P. O. Box 678

                              Clinton, IL 61727

                              Tel 217 935-6220

                              Fax 217 935-4632


  POWER                       Wayne D.  Romberg

                              Assistant Vice President - Vice President

An Illinova Company



                              July 2, 1997

Docket No. 50-461             10CFR21.21

Document Control Desk

Nuclear Regulatory Commission

Washington, DC 20555

Subject:  10CFR21 Interim Report 21-97-015: Improper

          Clearance for Westinghouse Model 50DHP350

          Circuit Breaker Arc Chute Rear Arc Horn Contact

Dear Madam or Sir:

     On May 7, 1997, Illinois Power (IP) identified that five arc chutes,

manufacturer part number 56F417G02, for Westinghouse model 50DEP350,

1200-amp, 4160-volt circuit breakers, in stores exhibited an inadequate

clearance between the rear arc horn and the arc chute molded case.

Because of the inadequate clearance, additional force was required on the

pole unit to allow the arc chute to attach to the front arc chute

support.  When attempts were made to install a replacement arc chute in

the "N" Residual Heat Removal (RHR) system pump breaker, the pole unit of

the circuit breaker seemed to deflect upwards.  Attempts were made to

install the arc chute on all three phases of the breaker with the same

result.  A suitable replacement for the RHR pump breaker arc chute was

located from a Clinton Power Station spare breaker.

     This issue has been identified as potentially reportable under the

provisions of 10CFR21.  IP's evaluation of this condition under 10CFR21

has not yet been completed.  Discussions between Clinton Power Station

and Westinghouse (Cutler-Hammer) are continuing in an attempt to resolve

this issue.  IP does not have a firm date for resolving this issue but

will provide, as a minimum, an update on the resolution progress by

August 29, 1997.



     Additional information about this issue may be obtained by

contacting D. G. Lukach, Plant Engineering, at (217) 935-8881, extension


                                        Sincerely yours,

                                        Wayne D.  Romberg

                                        Assistant Vice President


cc:  NRC Clinton Licensing Project Manager

     NRC Resident Office, V-690

     Regional Administrator, Region III, USNRC

     Illinois Department of Nuclear Safety

     INPO Records Center

     Westinghouse (Cutler-Hammer)


Page Last Reviewed/Updated Monday, March 30, 2020