05000312/LER-1980-009, Forwards LER 80-009/03L-0

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Forwards LER 80-009/03L-0
ML19344D275
Person / Time
Site: Rancho Seco
Issue date: 02/28/1980
From: Mattimoe J
SACRAMENTO MUNICIPAL UTILITY DISTRICT
To: Engelken R
NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION V)
Shared Package
ML19344D276 List:
References
NUDOCS 8003110627
Download: ML19344D275 (2)


LER-1980-009, Forwards LER 80-009/03L-0
Event date:
Report date:
3121980009R00 - NRC Website

text

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l SACRAMENTO MUNICIPAL UTILITY DISTRICT C 6201 S Street, Box 15830, Sacramento, California.95813; (916) 452-3211 4

February 28, 1980 Mr. R. H. Engelken, ' Director Region V Office of Inspection & Enforcement U. S. Nuclear Regulatory Commissicn Suite 202, Walnut Creek Plaza 1990 North California Boulevard Walnut Creek, California 94596 Re: Operating License DPR-54 Docket No. 50-312 Reportable O'currence 80-9 c

Dear Mr. Engelken:

In accordance with Technical Specifications for Rancho Seco Nuclear Generating Station, Section 6.9.4.2a and Regulatory Guide 1.16, Revision 4, Section C.2.b(1), the Sacramento Municipal Utility District is hereby submitting a thirty-day re, port of Reportable Occurrence 80-9.

On February 7, 1980, while performing function tests of relays in breaker 4A09, 4160V feeder breaker to the Nuclear Service transformer X43A, it was discovered that the reloading contact SFAX was not wired. A subsequent examination of breaker 4B05, 4160V feeder breaker to the Nuclear Service transformer X43B, revealed that'the corresponding contact on the "B" side, SFBX, was also not wired.

l The entire function of these particular contacts is to assure automatic closure of the 4160V feeder breakers to the Nuclear Transformers (X43A and X43B) following a loss of offsite power and SEAS initiation.

However, a parallel contact within the control circuit performs the identical function under all i

circumstances and plant configurations with one exception.

If the 4160V feeder break.er is in the open position prior to the loss of offsite power and subsc-quent SEAS initiatio', an automatic reclosure would not occur without these j

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contacts. However, to be in that configuration during power operation and still

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the requirements of Technical Specifications Sections 3.7.2E and 3.7.2G, meet l

the two Nuclear Service 480V buses, 3A and 3B, would have to be crosstied.

Although not specificallyfprohibited, that particular configuration was-not considered prudent during power operation. As a result, Rancho Seco has never utilized the crosstie breakers except during outages when the reactor was shut down.

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An investigation revealed that a discrepancy between the design drawing and the internal wiring diagrams for the switchgear resulted in the con'. acts being left unwired during construction.

Due to the parallel contact within the circuit, all integrated testing of the unloading scheme and SEAS circuits were successful and the discrepancy remained undetected until this time.

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j Mr. R. H. Engelken Page 2 February, 28, 1980 3

Upon' disc'very, the proposed corrective action was to issue the o

appropriate drawing changes required to wire the contacts.

However, due to

'recent plant modifications required by NUREG-0578 (i.e., providing emergency power for pressurizer heaters on loss of offsite power), the capability to crosstic the A and B.480V Nuclear Service huses was removed.,Since it is now physically impossible to be in a plant configuration where the contact is required to assure the system performs its intended function, the necessity for these contacts within the control circuits no longer exists. The contacts will thus remain unwired and the appropriate inhouse documentation (i.e., Non-Conforming.

Report) initiated to assure the affected drawings are revised to reflect the current wiring configuration.

l Since the plant'was shut down for refueling, there were no plant transients nor power reductions associated with this event.

Respectfully submitted,

',I QQ

(. J. Mattimoe 4

Assistant General Manager i'

and Chief Engineer JJM:HH: jim cs: Dir2ctor, MIPC (3)

Director, I&E (30)

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