ML20040A569

Interim Deficiency Rept,Updating 801013 Submittal,Re Failure of Gould Brown-Boveri Type J-13 Auxiliary Relays.Util Has Requested Vendor to re-examine Failed Coils.Next Rept Will Be Submitted by 820215

ML20040A569
Person / Time
Site:	Zimmer
Issue date:	12/30/1981
From:	Borgmann E CINCINNATI GAS & ELECTRIC CO.
To:	James Keppler NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION III)
References
10CFR-050.55E, 10CFR-50.55E, QA-1550, NUDOCS 8201210253
Download: ML20040A569 (3)

Text

_ _ _

o I

THE CINCINNATI GAS & ELECTRIC COMPANY c1 F CINCINN ATI. OHIO 452ol December 30, 1981 QA-1550

E. A. BORG M AN N ,

% vect Par.siothy

]

j p Q, U. S. Nuclear Regulatory Commission 4

i Region III RECEIVED $

799 Roosevelt Road Glen Ellyn, Illinois 60137

)

2-Attention: Mr. J. G. Keppler, 8 g M EWI Director a RE: WM. H. ZIMMER NUCLEAR POWER STATION - UNIT I O

10CFR50.55(e) - ITEM E-12 BROWN-BOVERI TYPE J-13 AUXILIARY RELAYS - DOCKET NO. 50-358, CONSTRUCTION PERMIT CPPR-88, W. O. #57300, JOB E-5590, FILE NO. NRC-7 Gentlemen:

This letter is intended to update our interim report, QA-1352, dated October 13, 1980, concerning the failure of the Gould Brown-Beveri Type J-13 Auxiliary Relays.

Our investigation has revealed that the relays are utilized in the following systems:

1) Nuclear Steam Supply Shutoff System (NB)

2) Drywell Pneumatic System (IN)

3) Reactor Core Isolation Cooling System (RI)

4) Primary Containment Ventilation System (VP)

5) Diesel Generator System (DG) *

6) Auxiliary Power System (AP)

7) Reactor Recirculation System (RR)

A review of the schematic diagrams for the above systems demonstrated that in the majority of cases the relays were neither continuously energized 820 1210 153'

. .rE2 6 JAn is ng Qe

o 6

, J. G. Keppler Director U. S. Nuclear Egulatory Commission Region III December 30, 1981 - QA-1550 Page 2 (therefore not subject to coil burnout) nor performing essential functions.

Exceptions were found in the NB, IN, and VP systems. Here the relays are utilized to monitor circuits supplying power to 250V DC motor operated isolation valves.

On loss of volatage these relays initiate an alarm in the control room and remove control power from the magnetic starters. Failure of the relays would result in the loss of the safety function. We are considering revising the control circuit to either, 1) eliminate the function which removes the control voltage or 2) bypassing the contact except during surveillance testing.

As stated in our previous report, the failures of the relays on DC circuits have been from open circuited coils. The relays were returned to the vendor in November, 1980. An analysis was requested to determine the cause of the failures, and was received on August 10, 1981.

The vendor's report indicates that the probable cause of coil failure was due to the application of excessive input voltage. The report also states that the history of the reliability of those relays is excellent, both in nuclear and non-nuclear applications. The report concludes that these are random failures, possible caused by over-voltage.

CG&E does not agree that the cause of failure is the application of over-voltage. The relays are designed to withstand a maximum input voltage of +10% of nominal (137.5 or 275 volts respectively for 125 and 250 volt relays). The maximum voltages at ZPS-1 for the 125 volt and 250 volt DC systems is 138 and 276 volts (+10.4%) respectively.

During subsequent discussions the vendor stated that the J-13 relays had been tested at 140 and 280 volts. As verbally reported to CG&E, the results of the test demonstrated that the relay is capable of continuous operation at these elevated voltages. The vendor la supplying written con-firmation of the test results. Based on this we conclude that the relays were not subjected to an over-voltage that they were incapable of withstanding.

Because the vendors initial report is inconclusive, we have requested that the failed coils be re-examined. The vendor has agreed to disassemble the relays coils to try to determine the cause of failure.

When the vendors report is received we will inform you of the results of the analysis and our final decision regarding the redesign of control circuits. Our next report will be submitted on Fearuary 15, 1982, t i

o e

9 J. G. Keppler Director U. S. Nuclear Regulatory Commission Region III December 30, 1981 Page 3 We trust that the above will constitute an acceptable interim status report under 50.55(e).

Very truly yours, Tile CINCINNATI GAS & ELECTRIC COMPANY j By E. A. BORGMANN SENIOR VICE PRESIDENT MAP:ec cc: NRC Resident Inspector Attn: W. F. Christianson NRC Of fice of Inspection & Enforce aent Washington, D. C. 20555 l

t l

___________________________________