United States Nuclear Regulatory Commission - Protecting People and the Environment


ACCESSION #: 9703060182



                                                  Illinois Power Company

                                                  Clinton Power Station

                                                  P.O. Box 678

                                                  Clinton, IL 61727

                                                  Tel 217 935-5623

                                                  Fax 217 935-4632



                                                  Wilfred Connell

ILLINOIS                                          Vice President

  POWER                                           U-602704

                                                  4F.140



                                                  WC-123-97

                                                  February 27, 1997



Docket No. 50-461                                 10CFR21.21



Document Control Desk

Nuclear Regulatory Commission

Washington, D. C. 20555



Subject:  10CFR21 Final Report 21-97-004: Phoenix Power Systems Regulated

          Power Transformer Supplied and Qualified by United Controls

          International is Not Capable of Operating Over the Required

          Output Range



Dear Madam or Sir:



     On January 7, 1997, Illinois Power (IP) initiated Condition Report

1-97-01-062 due to regulated power transformer 1AP75ERT tripping several

times for no known reason.  The transformer was installed under Plant

Modification AP-028 to resolve a degraded voltage relay setting

condition.  The first trip occurred after the modification was released

for operations.  An investigation of the cause of the trips determined

that the transformer tripped off with the addition of step load from a

low or no load condition.  IP has been advised by the manufacturer that

the transformer units require a minimum load of 2 amps per phase to

remain stable, contrary to the purchase specification which requires

voltage control from the no load condition to unit rating.  The safety-

related 120-volt distribution panel fed by the transformer de-energizes

when the transformer trips.  This issue was identified as potentially

reportable under the provisions of 10CFR, Part 21.



     The regulated power transformer is model number P3C015C6/EAN

Guardian Power Conditioner manufactured by Phoenix Power Systems.  The

transformer was qualified Class 1E and supplied to Clinton Power Station

by United Controls International.



     On the basis that the transformer does not meet the requirements of

the procurement document, and the failure of the transformer to perform

its function could result in the loss of power to safety-related

equipment loads, IP has concluded that this issue is reportable under the

provisions of 10CFR, Part 21.



                                                            U-602704

                                                            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)       Wilfred Connell, Vice President of IP, Clinton Power Station,

          Post Office Box 678, Clinton, Illinois, 61727, is the

          responsible officer notifying the Nuclear Regulatory Commission

          of a condition reportable under the provisions of 10CFR, Part

          21.



(ii)      The basic component involved in this condition is a dry type

          regulated power transformer, Phoenix Power Systems model number

          P3C015C6/EAN Guardian Power Conditioner.



(iii)     The regulated power transformer was manufactured by Phoenix

          Power Systems, San Diego, California.  The unit was qualified

          Class 1E and supplied to Clinton Power Station by United

          Controls International, Stone Mountain, Georgia.



(iv)      The purchase specification requires voltage control from the no

          load condition to unit rating.  Contrary to this requirement,

          IP has found that the transformer is not stable in the no load

          condition and trips when lightly loaded under various plant

          conditions.  A trip of the transformer upon addition of a

          safety load could cause the loss of power to all the loads fed

          by that transformer and result in the failure of safety related

          equipment to perform intended safety functions.



(v)       The repeated tripping of the regulated power transformer was

          identified and determined potentially reportable under the

          provisions of 10CFR21 on January 7, 1997.



(vi)      Clinton Power Station (CPS) has 4 of the potentially affected

          transformers installed in the Division 2 electrical system

          under Plant Modification AP-028.  Only one of the four units

          has experienced tripping problems.



(vii)     IP is disconnecting the four potentially affected transformers

          from the Division 2 electrical system to remove them from

          service in accordance with Plant Modification AP-032.  IP and

          representatives of United Controls are working on a network of

          filters/surge suppressors and minimum load resistors to

          eliminate the tripping problem.



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

          licensees.



                                                       U-602704

                                                       Page 3



     Additional information about this issue may be obtained by

contacting A. B. Haumann, Engineering Projects, at (217) 935-8881,

extension 4078.



                                        Sincerely yours,



                                        Wilfred Connell

                                        Vice President



RSF/krk



cc:  NRC Clinton Licensing Project

     Manager NRC Resident Office, V-690

     Regional Administrator, Region III, USNRC

     Illinois Department of Nuclear Safety

     INPO Records Center

     United Controls International



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