ML20206Q649

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Part 21 Rept 87-05 Re Possible Loss or Degradation of Reactor Protection Sys Channels a & B or C & D Due to Common Amplifier Failure.Initially Reported on 870403.Caused by B&W Design Error.Isolation Amplifiers Will Be Used
ML20206Q649
Person / Time
Site: Rancho Seco
Issue date: 04/06/1987
From: Julie Ward
SACRAMENTO MUNICIPAL UTILITY DISTRICT
To: Martin J
NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION V)
References
REF-PT21-87, REF-PT21-87-097-000 87-05, 87-5, JEW-87-511, PT21-87-097-000, PT21-87-97, NUDOCS 8704220010
Download: ML20206Q649 (2)


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SACRAMENTO MUNICIPAL UTIUTY DISTRICT O P. o. Box 15830, Sacramento CA 95852-1830,(916) 452-3211 APR 0 61987 AN ELECTRIC SYSTEM SERVING gg773 -8 In THE S: HEART ONALIFOR!

i JEW 87-511 g J. B. Martin Regional Administrator Region V Office of Inspection & Enforcement U. S. Nuclear Regulatory Commission 1450 Maria Lane, Suite 210 Walnut Creek, CA 94596 Docket No. 50-312 Rancho Seco Nuclear Generating Station Unit #1 License No. DPR-54 10 CFR 21 REPORT 87-05, POSSIBLE IDSS OF RPS CHANNELS A AND B OR C AND D DUE TO COMMON AMPLIFIER FAILURE

Dear Mr. Martin:

In accordance with 10 CFR 21.21(b)(2), the Sacramento Municipal Utility District hereby submits a written report documenting the notification made by Mr. Ron Colombo of the District to Mr. L. Miller of Region V Nuclear Regulatory Commission (NRC) on April 3, 1987.

The notification concerns the possible loss or degradation of both RPS channels A and B or channels C and D which are used in the overpower and the power / pump trips. A failure in the common amplifier to channels A and B or channels C and D could result in the loss of both channels total reactor power signals or possibly cause these signals to vary to some unknown value.

This failure was identified in a February 24, 1987 letter from Babcock and Wilcox to Mr. R. A. Dieterich of the Sacramento Municipal Utility District. The concern was detected during a review of SMUD drawings for the RPS b:t B&W in preparation of a proposal to SMUD for providing Extended Range Nuclear Instrumentation.

Upon receipt of the B&W Report by Nuclear Licensing, an internal occurrence description report (ODR) was initiated to further investigate this type of failure mode. The ODR was determined to be reportable to the NRC as a Licensee Event Report (LER). A more detailed description and corrective actions will be reported in LER 87-23 which will be submitted by April 9, 1987.

8704220010 870406 PDR ADOCK 05000312 10 3 PDR 26/9 RANCHO SECO NUCLEAR GENERATING STATION O 14440 Twin Cities Road, Herald, CA 95638-9799;(209) 333-2935

, e . t J B MARTIN April 6, 1987 The common RPS amplifier configuration does not conform to the guidance in IEEE-279 concerning channel independence or separation. Failure of this device has been determined to be a condition involving a basic component that could contribute to the exceeding of the safety limits as defined in the Rancho Seco Technical Specifications section 2.3. The common failure mode is being reported pursuant to 10 CFR 21.3(d) (4). _

Resolution of the common failure mode may be achieved by the use of isolation amplifiers. The isolated output could then be an input to the average power amplifier.

The common RPS channel amplifiers were installed prior to initial operation. This design was provided by the B&W Company. A cursory review by B&W for the other 177 FA plants indicated that all other plants achieve the required channel isolation and separation.

If there are any questions concerning this report, please contact Mr. Ron Colombo at (916) 452-3211, extension 4236.

Since ely,

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/ o . Ward R D'eputy General Manager, Nucle cc: A. D'Angelo G. Kalman J. Martin (2)

INPO

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