United States Nuclear Regulatory Commission - Protecting People and the Environment


ACCESSION #:  9709050020



                                        Illinois Power Company

                                        Clinton Power Station

                                        PO Box 678

                                        Clinton IL 61727

ILLINOIS                                Tel 217 935-6220

     POWER                              Fax 217 935-4632

 An Illinova Company

                                        Wayne D.  Romberg

                                        Assistant Vice President Nuclear



                                        U-602823

                                        4F.140



                                        August 28, 1997



Docket No.  50-461                      10CFR21.21



Document Control Desk

Nuclear Regulatory Commission

Washington, D. C. 20555



Subject:  10CFR21 Final Report 21-97-015: Improper Clearance for

          Westinghouse Model 50DHP350 Circuit Breaker Arc Chute

          Rear Arc Horn



Dear Madam or Sir:



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

manufacturer part number 567F417G02, for Westinghouse Model 50DHP350,

4160-volt circuit breakers, in stores were different in configuration

from the original arc chute and exhibited an inadequate clearance between

the rear arc horn and the arc chute molded case during installation.

Because of the inadequate clearance, excessive force would be required on

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

chute support.  When attempts were made to install one of the arc chutes

in the "A" Residual Heat Removal (RHR) system pump breaker, the line pole

unit of the circuit breaker deflected 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 on an original spare breaker.  Condition report 1-97-05-085 was

initiated to track investigation and resolution of this issue.  This

issue was identified as potentially reportable under the provisions of

10CFR, Part 21.



     IP notified the NRC via letter U-602779, dated July 2, 1997, that

the investigation of the arc chute rear arc horn issue was not completed

and additional time was needed to complete the investigation.  IP has now

completed the evaluation of this condition under 10CFR21 and concludes

that this issue should be reported under the provisions of 10CFR21.  The

basis for this conclusion is that installation of the arc chute could

cause the line pole unit to deflect, potentially causing the main and

arcing contacts to be out of adjustment and potentially affecting the

safety related function of the circuit breaker.  The failure of the

breaker to operate properly could result in the loss of power to safety-

related equipment loads.  The breaker's function is to supply Class 1E

power until a fault occurs (trip open) and shed loads, or close on demand

and supply Class 1E power to safety-related equipment.



                                                            U-602823

                                                            Page 2



     IP is providing the following information in accordance with

10CFR21.21(c)(4).  Initial notification of this matter will be provided

by facsimile of this letter to the NRC Operations Center in accordance

with 10CFR21.21(c)(3) within two days of the date the responsible officer

signs this letter.



(i)       Wayne D.  Romberg, Assistant Vice President of IP, Clinton

          Power Station, Highway 54, 6 Miles East, Clinton, Illinois,

          61727, is informing the Nuclear Regulatory Commission of a

          condition reportable under the provisions of 10CFR, Part 21.



(ii)      The basic component involved in this condition is the arc

          chute, manufacturer part number 567F417G02, for Westinghouse

          Model 50DHP350, 4160-volt circuit breakers.



(iii)     The arc chute and rear arc horn were supplied to Clinton Power

          Station by Westinghouse, Pittsburgh, PA.



(iv)      The arc chute appears to be different in configuration from the

          original arc chute and exhibited an inadequate clearance

          between the rear arc horn and the arc chute molded case during

          installation.  Specifically, the replacement rear arc horn

          contact currently in production for the breaker appears to be

          different from the original rear arc horn contact installed in

          the breaker.  The major differences appear to be the position

          and angle of bend for the contact.  Because of the inadequate

          clearance that occurs during installation, excessive force

          would be required on the line pole unit to allow the arc chute

          to attach to the front arc chute support.  When attempts were

          made to install one of the arc chutes in the "A" Residual Heat

          Removal (RHR) system pump circuit breaker, the line pole unit

          of the breaker deflected upward, indicating excessive tension

          on the unit.  Attempts were made to install the arc chute on

          all three phases of the breaker with the same result.



          IP has concluded that this issue should be reported under the

          provisions of 10CFR21.  The basis for this conclusion is that,

          despite assurance from the supplier that the arc chute is the

          correct part, IP is unable to determine if the rear arc horn

          can be installed without adverse impact on the circuit breaker.

          Installation of the arc chute could cause the line pole unit to

          deflect, potentially causing the main and arcing contacts to be

          out of adjustment and adversely affecting the safety-related

          function of the circuit breaker.  The impact of the additional

          stress applied to the pole units is not known.  However, the

          failure of the breaker to operate properly could result in the

          loss of power to safety-related equipment loads.  The breaker's

          function is to supply Class 1E power until a fault occurs (trip

          open) and shed loads, or close on demand and supply Class 1E

          power to safety-related equipment.



                                                            U-602823

                                                            Page 3



(v)       The improper clearance condition was identified and determined

          potentially reportable under the provisions of 10CFR21 on May

          7, 1997.  IP notified the NRC in a letter dated July 2, 1997,

          that the investigation of the issue was not complete, and

          additional time was needed for completion.



(vi)      Clinton Power Station (CPS) has 5 of the potentially affected

          arc chutes in stores.  When attempts to install the deficient

          arc chute were unsuccessful, a suitable replacement arc chute

          was located on an original spare circuit breaker.  None of the

          deficient arc chutes have been installed in the plant.  IP is

          not aware of other facilities that could be affected by this

          deficiency.



(vii)     The deficient arc chutes are currently on hold and will not be

          released for installation until appropriate corrective actions

          are identified that allow proper installation of the arc chute.

          Discussions between CPS and Westinghouse (Cutler-Hammer) are

          continuing in an attempt to resolve this issue.



(viii)    IP has no advice about this issue for other purchasers or

          licensees.



     Additional information about this issue may be obtained by

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

3952.



                                   Sincerely yours,



                                   Wayne D.  Romberg

                                   Assistant Vice President



RSF/krk



cc:  NRC Clinton Licensing Project Manager

     NRC Resident Office, V-690

     Regional Administrator, Region III, USNRC

     G. C.  Wright, Region III, USNRC

     Illinois Department of Nuclear Safety

     INPO Records Center

     Westinghouse

     Eaton Cutler-Hammer



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