ML20149G145

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Forwards Revised Response to Generic Ltr 86-05,per Mods & Recalculations Performed on Pressure & Temp Instruments Described in 870428 Submittal
ML20149G145
Person / Time
Site: Rancho Seco
Issue date: 02/10/1988
From: Firlit J
SACRAMENTO MUNICIPAL UTILITY DISTRICT
To: Miraglia F
Office of Nuclear Reactor Regulation
References
AGM-NPP-88-067, AGM-NPP-88-67, GL-86-05, GL-86-5, NUDOCS 8802180136
Download: ML20149G145 (2)


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SACRAMENTO MUNICIPAL UTILITY DISTRICT C P. O. Box 15830. Sacramento CA 95852 1830,(916) 452-3211 AN ELECTRIC SYSTEM SERVING THE HEART OF CALIFORNIA AGM/NPP 88-067 February 10, 1988 U. S. Nuclear Regulatory Commission Attn: Frank J. Miraglia, Jr.

Associate Director for Projects Phillips Building 7920 Norfolk Avenue Bethesda, MD 20014 Docket No. 50-312 Rancho Seco Nuclear Generating Station License No. DPR-54 REVISION TO THE DISTRICT'S RESPONSE TO GENERIC LETTER NO. 86-05

Dear Mr. Miraglia:

The District provided its original response to Generic Letter 86-05 on April 28,1987.

Subsequent to this submittal modifications and re-calculations were performed on the pressure and temperature instruments described in the original submittal. These changes have necessitated a revision to our submittal. Attached is the revised section reflecting the associated changes in the instrument uncertainties.

Please contact me if you have any questions. Members of your staff with questions requiring additional information or clarification may contact Mr. John Atwell at (209) 333-2935, extension 4917.

Si ncerely, b

f Joseph F. Firlit Assistant General Manager, Nuclear Power Production Attachment cc:

G. Kalman, NRC, Bethesda A. D'Angelo, NRC, Rancho Seco J. B. Martin, NRC, Walnut Creek 8802180136 880210 PDR ADOCK 05000312 P

PDR nANCHO SECO NUCLEAR GENERATING STATION O 14440 Twin Cities Road, Herald. CA 95638-9739;(209) 333-2935

ATTACHMENT

.s3 Revised Response to Generic letter 86-05 (Revision required to Section A.2 only)

A.

Determination of RCP Trip Criteria 2.

Identify.the instrumentation uncertainties for both normal and adverse containment conditions. Describe the basis for the selection of the adverse containment parameters.

Address, as appropriate, local conditions such as fluid jets or pipe whip which might influence the instrumentation reliability.

Response

The calculated uncertainties of the instrument strings (pressure and temperature) used to display subcooling margin are:

SPOS Nomal Adverse Pressure

+ 21 psig

+ 42 psig Temperature T 70F T 70F SMM Normal Adverse Pressure

+ 46 psig

+ 217 psig Temperature T 70F T 70F The adverse containment parameters are selected to envelop design basis accidents of concern (ie. SB LOCA and steamline break).

The pressure transmitter uncertainties for the SPOS reflect the installation of thermal enclosures to reduce the peak ambient temperatures experienced by the transmitters during adverse i

containment conditions.

Pipe whip and fluid jets will not affect the pressure t ansmitters as they are located outside the secondary shield wall. Each SMM display receives input from two RTDs which have sealable connection heads.

The highest temperature value is normally used and if one RTD is lost to pipe whip the other is used.

MEtt0589(02.12)

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