05000312/LER-1979-022, Forwards LER 79-022/01T-0

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Forwards LER 79-022/01T-0
ML20148C012
Person / Time
Site: Rancho Seco
Issue date: 01/10/1980
From: Mattimoe J
SACRAMENTO MUNICIPAL UTILITY DISTRICT
To: Engelken R
NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION V)
Shared Package
ML20148C015 List:
References
NUDOCS 8001240458
Download: ML20148C012 (2)


LER-2079-022, Forwards LER 79-022/01T-0
Event date:
Report date:
3122079022R00 - NRC Website

text

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SACRAMEf4TO MUfJICIPAL UTILITY DISTRICT C 6201 S Street, Box 15830, Sacramento, California 95813; (916) 452 3211 January 10, 1980 Mr. R. H. Engelken, Director Region V Office of Inspection & Enforcement U. S. Nuclear Regulatory Commission 1990 North California Boulevard Walnut Creek Plaza, Suite 202 Walnut Creek, California 94396 Re: Operating License DPR-54 Docket No. 50-312 Reportable Occurrence 79-22

Dear Mr. Engelken:

In accordance with Technical Specifications for Rancho Seco Nuclear Generating Station Section 6.9.4.11, and Regulatory Guide 1.16, Revision 4, Section C.2.a(9), the Sacramento Municipal Utility District is hereby submitting a fourteen-day followup report to the reportable occurrence which was initially reported to H. Canter, NRC Resident Onsite Inspector, on January 8, 1980, and by a confirmation letter on the same day.

On December 17, 1979, the Sacramento Municipal Utility District l received notification from Allis-Chalmers, manuf acturer of the 66" containment i purge isolation valves utilized at Rancho Seco Unit 1, of a potential problem associated with their Streamseal butterfly valves. The notification was basically a recommendation to limit the opening of the valves to a maximum of sixty degrees. Based on a 60 psig containment pressure (post LOCA condition),  ;

valve closure when valve dics position is in excess of sixty degrees may cause l the shaft torsional rating to be exceeded. l l

The District is presently participating in the Allis-Chalmers Corpora-tion valve qualification program. The notification was followed within 5 days with the results of their testing at NASA / Langley Research Center, Virginia.

The testing was performed on an Allis-Chalmers 6" Streamseal butterfly valve.

Through data co11cetion and calculation, a tabulation of torque coefficients was obtained which enables prediction of valve torques for any size Allis-Chalmers valve of similar design. These predictions are dependent on a number of considerations, some of which are:

a. Location of valve relative to upstream condition- .?xistence of an elbow or other interference in flow directioni.
b. Upstwa f acing disc geometry (curved side or flat side of disc facing upstream.
c. Disc thickness / diameter ratio.

i 800124 0 AN ELECTRIC 3) S T E M 3 E RVIN G MORE THAN C 0 0. 0 0 THE HEART OF C A LI F O R N I A j

, R. H. Engelken Page 2 January 10, 1980 As a result, specific information concerning the valves at Rancho Seco (piping configurations, upstream facing disc geometry, maximum temperatures and pressures assumed in the Safety Analysis, valve operator configuration, etc.) was forwarded to Allis-Chalmers on December 28, 1979. Utilizing this information, and as part of the District's contract with Allis-Chalmers, a statement relating our valves to the applicable NRC considerations,in Guidelines for Demonstration of Opera-bility of Purge and Vent Valves.will be forthcoming.

Corrective action concerning the valves will be dependent upon the context of said statement and any additional recommendations from Allis-Chalmers.

In the interim, from the receipt of the initial notification until an acceptable resolution concerning valve qualification is reached, the purge valves will not be opened during power operation. Basically, purging will be restricted to those time periods when the reactor is shut down.

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

Respectfully submitted, J. J. Mattimoc Assistant General Manager and Chief Engineer RIR: HH: jim cs: Director, MIPC (3)

Director, IE (40)

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