05000312/LER-1980-030, Forwards LER 80-030/03L-0

Forwards LER 80-030/03L-0

ML19320A908
Person / Time
Site:	Rancho Seco
Issue date:	06/26/1980
From:	Mattimoe J SACRAMENTO MUNICIPAL UTILITY DISTRICT
To:	Engelken R NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION V)
Shared Package
ML19320A909	List: 05000312/LER-1980-030, Forwards LER 80-030/03L-0 05000312/LER-1980-030-03, /03L-0:on 800623,while Performing I-108C,reactor Protection Sys Channel C Test,Overpower Bistable Voltage Setting Was Found Drifted Out of Spec.Caused by Malfunctioning of Semiconductor Voltage Regulator
References
NUDOCS 8007080270
Download: ML19320A908 (2)

LER-1980-030, Forwards LER 80-030/03L-0

Event date:
Report date:
3121980030R00 - NRC Website

text

.

e g' SMU=

~*

SACRAMENTO MUNICIPAL UTILITY DISTRICT C 6201 s Street, Box 15830. Sacramento, California 95813; (916) 452-3211 June 26, 1980 g.s 5 e i f

\\'A tb Uy-lk I

10 3

,E g'

• O Mr. R. H. Engelken, Director gN' Region V Office of Inspection and Enforcement

,/

4M' U. S. Nuclear Regulatory Commission 1990 North California Boulevard Walnut Creek Plaza, Suite 202 Walnut Creek, California 94936 Re: Operating License DPR-54 Docket No. 50-312 Reportable Occurrence 80-30

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 sub-mitting a thirty-day report of Reportable Occurrence 80-30.

On June 19, 1980, while performing procedure I-108C, RPS Channel C Test, the RPS C Overpower Bistable setpoint voltage was measured at 8.421 VDC.

The procedure requires 8.430 + 0.005 VDC. The reading, although out of tolerance per procedure, was not a Technical Specification violation since the setpoint drift was toward the conservative direction. The setpoint was readjusted to 8.430 VDC and a daily check was instituted.

On June 23, 1980, the setpoint voltage was measured at 8.444 VDC and drifting. This reading was in excess of the Technical Specification limit.

Technical Specifications Table 2.3.1 limits the setting to 105.5% power. This is equivalent to 8.440 VDC.

The 8.444 VDC is equivalent to 105.55% or 0.05% in excess of that limit. At this time the Overpower Bistable Module was replaced with a spare module from the warehouse and RPS Channel C was retested per the applicable sections of I-108C.

It was determined that the semi-conductor voltage regulator within the Bistable Module malfunctioned.

Since there have been no previous failures of the module, additional corrective action at this time does not appear to be warranted. The monthly tests are deemed adequate to detect potential future malfunct ' ms in this area.

@Wkg 8 007080 2 g my e m

, m nw n cev n m = m m w.,

wm

o..

Mr. R. H. Engelken Page 2.

June 26, 1980 The malfunctioning module was an'880 System Bistable Module, Part No. 6621500K1, S/N 880-118, manufactured.by Bailey Meter Co.

There were no power reductions nor plant transients associated with this event.4

- Respectfully submitted,

.7N.UI~M

. Mattimoe Assistant General Manager and Chief Engineer

~JJM:HH: Jim es:. Director, I&E (30)

Director,- MIPC (3)

.A L2.'G'

....m