ML20237B342

Provides Addl Info Re Approach to Meet Before Restart Commitments Addressing Divergance Zone Wind Flow Phenomenon Into Dose Projection & Developing Protective Action Recommendations of Meteorological Sys Program Improvements

ML20237B342
Person / Time
Site:	Rancho Seco
Issue date:	12/08/1987
From:	Coward G SACRAMENTO MUNICIPAL UTILITY DISTRICT
To:	Miraglia F NRC
References
AGM-TA-87-265, NUDOCS 8712160203
Download: ML20237B342 (2)

Text

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gSMUD SACRAMENTO MUNICIPAL UTILITY DISTRICT C P. O. Box 1583o, Sacramento CA 95852-1830,(916) 452-3211 ,

AN ELECTRIC SYSTEM SERVING THE HEART OF CAllFORNIA ]

DEC 0 81987 l

~

AGM/TA 87-265 -

U. S. Nuclear Regulatory Commission Attn: Frank J. Miraglia, Jr.

Associate Director for Projects' Philips Bldg.

7920 Norfolk Avenue

Bethesda, MD 20014 )

DOCKET 50-312 RANCHO SECO NUCLEAR GENERATING STATION LICENSE NO. DPR-54 METEOROLOGICAL SYSTEM PROGRAM IMPROVEMENTS

Dear Mr. Miraglia:

On October 29, 1987, in letter GCA 87-733, the District made various before I and after restart commitments that address integrating divergence zone wind flow phenomenon into the dose projection, and developing protective action recommendations. The purpose of this letter is to provide more infonnation concerning the approach to meet the before restart commitments, which are:

1. Examine existing literature on the divergence zone meteorological phenomenon to broadly assess the uncertainty in the dose projection results of the existing Class A straight-line Gaussian model.

2. Modify the existing Emergency Plan and affected implementing

,.rocedures to modify Protection Action Recommendations to compensate for the identified uncertainties.  ;

The District has already completed commitment no.1 by reviewing the 1981 study, " Meteorological Review for the Rancho Seco Emergency Preparedness Program," which identified the divergence zone flow phenomenon. The second commitment is presently under consideration by the Emergency Preparedness (EP) i Group. EP will modify Section 6, Emergency Measures, and Section 7, Emergency i Response Facilities and Equipment of the Emergency Plan, as well as several related Emergency Plan Implementing Procedures:

EPIP-5430 - Control Room Dose Assessment  !

EPIP-5440 - Technical Support Center Dose Assessment EPIP-5450 - Emergency Operations Facility Dose Assessment EPIP-5460 - Protective Action Recommendations The following outlines the approach the District will be taking to implement the changes within the above listed documents:

Q 8712160203 871208 PDR F

ADDCK 05000312 PDR

)\D RANCHO SECO NUCLEAR GENERATING STATION O 14440 Twin Cities Road, Herald, CA 95638-9799;(209) 333 2935

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• DEC C 81937 AGM/TA 87-265 j Frank J. Miraglia, Jr. The District will be integrating its newly implemented Weather Services Incorporated (WSI) modem data link capability into its dose projection I techniques. The WSI link provides National Weather Service (NWS) station wind speed, wind direction, and Pasquill stability class hourly observations at 16 NWS first-ordered stations within the RSNGS Ingestion Planning Zone. Use of the WSI link permits the acquisition of concurrent meteorological data from Sacramento and Rancho Seco at both the Unified Dose Assessment Center (UDAC) and Technical Support Center (TSC).

The divergence zone wind flow phenomenon generally occurs with the

, establishment of the semipermanent high pressure zone over the eastern Pacific i Ocean. This climatological feature is conducive to seabreeze flows, which due to the unique topography of the Carquinez Straits and the San Joaquin and Sacramento Valleys, results in divergence zone flows mainly during April-0ctober daytime periods. The dose projection scheme will be modified to ,

allow the Radiological Assessment Coordinator (RAC) in the TSC and the Dose Assessment Coordinator (DAC) in the UDAC to continuously acquire concurrent l Sacramento and Rancho Seco meteorological data to establish the existence of i divergence zone flows.

],

Once divergence zone flows are identified, the downwind sector will be l replaced by a " divergence zone sector," bounded on one side by the Sacramento wind direction and the other side by the Rancho Seco wind direction. The protective actions will be implemented in the sectors " downwind" of the l

divergence zone sector and its two adjoining 22.5 degree sectors. A commonly occurring divergence zone flow shows southerly winds at Sacramento and westerly winds at Rancho Seco. Under this condition, the divergence zone sector is south through west or 90 degrees azimuth, while the protective actions region will be NNW through ESE, or 135 degrees azimuth in range.

The District expects the Emergency Plan and implementing procedures to be completed in mid-January,1988. Rough drafts could be made available by the beginning of 1988.

Please contact me if you have any comments or questions. Members of your staff with comments or questions requiring additional information or

, clarification may contact Mr. Richard Mannheimer at (209) 333-2935, extension l 4919.

Sincerely /7 George A. Coward Assistant General Manager, l Technical and Administrative Services l

cc: G. Kalman, NRC, Bethesda i A. D'Angelo, NRC, Rancho Seco i

J. B. Martin, NRC, Walnut Creek I. Spickler, NRC, Bethesda R. Fish, NRC - Region V, Walnut Creek