ML20236E373

Safety Evaluation Supporting Existing & Proposed Mods to Meteorological Program & W/Planned Improvements,Facility Will Satisfy Min Meteorological Emergency Preparedness Requirements of 10CFR50.47 & 10CFR50,Apps E & F

ML20236E373
Person / Time
Site:	Rancho Seco
Issue date:	07/24/1987
From:	NRC
To:
Shared Package
ML20236E358	List: ML20236E354 ML20236E373
References
NUDOCS 8707310341
Download: ML20236E373 (4)

Text

/ 'o g UNITED STATES

! n NUCLEAR REGULATORY COMMISSION 5 ;E WASHINGTON, D. C. 20555

\...../ ,

ENCLOSURE SAFETY EVALUATION ~ i l

RANCHO SECO ONSITE METEOROLOGY PROGRAM i

1.0 INTRODUCTION

By previous commitment, Sacramento Municipal Utility District, the licen-see for Rancho Seco, indicated that there would be an adequate onsite meteorology program in place prior to restart following the December 26, 1985 overcooling transient. In particular, concerns were identified with the adequacy of the onsite meteorological program as it relates to the 1

, emergency preparedness requirements which define the minimum meteorological i

monitoring requirements. This safety evaluation presents the staff 1 evaluation of the adequacy of the short-term meteorological program improvements proposed by the licensee for restart.

2.0 DISCUSSION i The regulatory requirements for emergency response at nuclear power plants l with specific meteorological considerations characterized in the form of atmospheric transport and diffusion conditions as an integral part of the dose assessment capability are covered by the requirements of 10 CFR 50.47(b)(9), 10 CFR 50, Appendix L, IV.B. and 10 CFR 50, Appendix F, Do$k@{$724 PD

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IV.E.2. These regulations state that emergency plans, facilities, and j equipment at nuclear power plants shall be capable of determining the l i

magnitude of, and continually assessing, actual and potential offsite J consequences resulting from the release of radioactive material to the j environment. To accomplish these regulatory objectives, knowledge of  ;

j current transport and diffusion conditions is needed in order to assess  ;

i the impacts of actual releases. .Further, estimates of future or forecast  !

conditions are needed in order to assess the impacts of potential releases. l All of this information must be in a form to permit continual dose assess-ments. .,

l To develop the atmospheric transport and diffusion information of impor- l tance to emergency response, representative meteorological data and an i appropriate model are required. Minimum meteorological data requirements for emergency response at nuclear power plants are outlined in Supple-1 ment 1 to NUREG-0737 and are considered in conjunction with the more  !

I specific data collection guidance contained in Regulatory Guides (RG) 1.23, 1.101 and 1.97 (Revision 2). Atmospheric transport and dif--

fusio;, modeling considerations for emergency response are discussed in detail in RG 1.101.

4 The minimum meteorological information required for emergency response purposes is a continuous record of reliable meteorological parameters (wind. speed, wind direction, and a measure of atmospheric stability) as specified in Supplement 1.to NUREG-0737 and RG 1.97 (Revision 2) for site f

meteorology. This data should be incorporated into a simple, rapid l

j-V l running transport and diffusion model which is part of the dose calcula-tion model to be utilized in the control room.

3.0 EVALUATION Since initial licensing of Rancho Seco, the licensee has been measuring wind speed, wind direction, and air temperature at the 10 meter and 60 meter levels from a tower located on the Rancho Seco site. These measure-ments of wind speed, wind direction and atmospheric stability (temperature gradient with height) have been measured at the appropriate levels to properly represent the diffusion and transport conditions for the purpose of estimating potential accident release. They are also recorded contin-uously in the control room. However, historically, the data has not been reliable and it has been questionable as to whether the measurements meet the guidelines of RG 1.23 and RG 1.97 (Revision 2). These diffi-culties have resulted from instrumentation problems and inadequate quality control and quality assurance.

By letter dated February 26, 1987, the licensee proposed modifications to l the Rancho Seco meteorology and dose assessment programs whi::h will be completed by restart. The licensee proposed to place the two temperature sensors located at the 10 meter tower elevation in the same shield in order to resolve the measured temperature divergence problems noted with these instruments. They also plan to provide indication of aspirator motor failure in the control room to enhance early detection and repair and thereby reduce the probability of the collection and use of erroneous

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data. In addition, the licensee will improve the quality control, quality assurance and training programs related to the meteorology program. The licensee has also committed to purchasing a spatial and temporal variable diffusion model prior to restart which will be incorporated into its dose assessment model. These changes will provide for better meteorological data collection and assimilation per the guidelines of RG 1.23 and RG 1.97 I (Revision 2) for post-accident emergency response. l

4.0 CONCLUSION

l Based on our review of the existing and proposed modifications to the meteorological program, the staff concludes that with the planned improve-ments, the Rancho Seco facility will satisfy the minimum meteorological emergency preparedness requirements of 10 CFR 50.47 and 10 CFR 50 Appen-dices E and F and the guidelines of RG 1.23 and RG 1.97 (Revision 2) at the time of restart. The onsite meteorology program is, therefore, accept-able. The staff recommends that discussions with the licensee continue during and after implementation of the program modifications, and that the licensee continue to send collected meteorological data on a quarterly basis to the staff to confirm that previously identified meteorological concerns have been resolved.

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