05000312/LER-1981-012, Forwards LER 81-012/01T-0.Detailed Event Analysis Submitted

Forwards LER 81-012/01T-0.Detailed Event Analysis Submitted

ML19343C541
Person / Time
Site:	Rancho Seco
Issue date:	03/16/1981
From:	Mattimoe J SACRAMENTO MUNICIPAL UTILITY DISTRICT
To:	Engelken R NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION V)
Shared Package
ML19343C542	List: 05000312/LER-1981-012, Forwards LER 81-012/01T-0.Detailed Event Analysis Submitted 05000312/LER-1981-012-01, /01T-0:on 810303,as-found Setpoints for High Reactor Bldg Pressure Trip Were Noted Exceeding Tech Spec. Caused by Instrument Drift.Switches Reset & Setpoints Revised
References
NUDOCS 8103240460
Download: ML19343C541 (2)

LER-1981-012, Forwards LER 81-012/01T-0.Detailed Event Analysis Submitted

Event date:
Report date:
3121981012R00 - NRC Website

text

T

• /

)SMUD SACRAMENTO MUNICIPAL UTILITY DISTRICT O 6201 S Street. Box 15830, Sacramento, California 95813; (916) 452 3211 March 16, 1981 J

D Mr. R. H. Engelken, Di rector Region V Of fice of Inspection & Enforcement

[ 'C b.g nf 1990 North Ca!Ifornia Boulevard

%>.d[g Walnut Creek Plaza, Suite 202

/c Walnut Creek, CA 94596 V )v#

f)

V jx Re:

Operating License DPR-54 Docket No. 50-312

% M ', F Reportable Occurrence 81-12

~

Dear Mr. Engelken:

In accordance with Technical Specifications for Rancho Seco Nuclear Generating Station, Section 6.9.4.le and Regulatory Guide 1.16, Revision 4, Section C.2.a(5), the Sacramento Municipal Utility District is hereby submitting a follow-up report to Reportable Occurrence 81-12 which was initially reported to Mr. H. Canter, resident NRC inspector, on March 4, 1981, and by a confirmation letter the same day.

On March 3, 1981, while reviewing a completed 1-111, RPS Channel Calibration Procedure, the "as found" setpoints for the "High Reactor Building Pressure" t rip were found out of tolerance.

Technical Specifi-cations Section 2.3 and Table 2.3-1 specify a maximum of 4.0 psig.

Acco rd-ingly, the procedure 1-111 and Process Standards established an adminis-trative setpoint of 3 9 1 0.05 psig.

However, due to instrument drift greater than 4.0 psig.

the setpoints on all four RPS channels were foune d

The four channeis, A, B, C and D "as found" settings were 4.08, 4.03, 4.05 and 4.05 respectively.

Since two out of four PPS Channel trips are required to trip the reactor, a "High Reactor Building Pressure" trip would have occurred at 4.05 psig rather than the maximum 4.0 psig called out by the Technical Specifications.

Upon discovery the setpoints were reset to the administrative limit of 3.9 + 0.05 psig.

However, subsequent review of this occurrence prompted revising the administrative retpoints.

Since the largest instrument drif t was in the order of 0.18 psig, both I-111 and the Process Standards setpoints were lowered by 0.20 psig to 3.7 1 0.05 psig.

The instruments were reset to the lower setpoints on March 4,1981.

This corrective action provides reasonable assurance that future instrument

~ drift wi11 not cause the Technical Specification 1imit to be exceeded.

810824D W 6

6 t?M f( M Z E R VI N G MORE THAN 600.000 IN THE HEART OF C All F O R N I A

Mr. R. H. Engelken 2

March 16, 1981 The four pressure switches, PSH-53606, PSH-53620, PSH-53617 and PSH-53619 are Model No. APW 7041-151 pressure switches manufactured by Mercold Corporation.

Since the plant was shutdown for refueling, there were no i

transients nor power reductions associated with this event.

Respectfully submitted, w. bleTA (I ohn Mattimoe Assistant General Manager I

and Chief Engineer JJM':HH:rm

.cs:

l&E Washington (30)

MIPC (3)

EPRI-NSAC i

j i

l' I

l-

)

j-i Il' t

i e s I

a

's o

w

. a.

c