ML20207G328

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Discusses Divergence Zone Study Tower Location.S&W Reevaluation of Tower Placements to Ensure Objectives of Divergence Zone Study Not Compromised Due to Aerodynamic Effects Exerted by Trees & Hills Found Acceptable
ML20207G328
Person / Time
Site: Rancho Seco
Issue date: 08/12/1988
From: Croley B
SACRAMENTO MUNICIPAL UTILITY DISTRICT
To:
Office of Nuclear Reactor Regulation
References
AGM-NTA-88-153, NUDOCS 8808240082
Download: ML20207G328 (2)


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$SMUDSACRAMENTO MUNit. PAL UTILITY olSTRICT O 6201 S Street, P.o. Box 15830 Sacramento CA 958521830,(916) 452 3211 AN ELECTRIC SYSTEM SERVING THE HEART OF CALIFORNIA AGM/NTA 88 153 AUG 1 2 1988 Director of Nuclear Reactor Regulation U. S. Nuclear Regulatory Commission Mail Station P1-137 Washington, DC 20555 Docket No. 50-312 Rancho Seco Nuclear Generating Station License No. DPR-54 DIVERGENCE ZONE STUDY TOWER LOCATION

Dear Sir:

Two of the three 10-meter meteorological towers designated for the divergence zone study were located at alternate sites. The District had Stone & Webster (SWEC) reevaluate the tower placements to ensure that the objectives of the divergence zone study are not compromised due to aerodynamic effects exerted by the trees and hills on the local wind field. After careful examination of the two new siting locations, SWEC concluded that the tower sitings are acceptable.

The northeast tower off Route 104 was relocated east of a grove of trees, the closest of which were estimated to be 30-35 feet in height. The minimum distance between the tower and the trees is approximately 290 feet (i.e.,

slightly less than 10 times the obstruction height). This situation is considered acceptable. The east tower, near the town of Ione was also relocated near a small grove of trees. This situation is not considered a problem, because the trees are situated to the east of the tower. Divergence zone events involve westerly winds, thus aerodynamic influence of the trees will not be a major factor. There were no problems with the location of the southeast tower off Highway 88, since it was sited at the location originally establi shed.

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O RANCHO SECO NUCLEAR GENERATING STATION D 1444o Twin Cities Road, Herald, CA 95638 9799;(209) 333 2935

.t-Director of NRR AGM/NTA 88-153 i AUG 12 588 During SWEC's visit to install wind sensors on the towers, the surrounding environment of each site was photographed and the terrain characteristics were documented. This information will be used to interpret the meteorological

, data if local wind patterns become affected.

Members of your staff with questions requiring additional information or clarification may contact Mr. Richard Mannheimer at (209) 333-2935, extension 4919.

Sincerely f-

/f p. ,

B. G. roley l Assistant General Manager, Technical And Administrative Services cc: J. B. Martin, NRC, Walnut Creek K. Prendergast, NRC, Walnut Creek I. Spickler, NRR, Rockville A. D' Angelo, NRC, Rancho Seco 9

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