Document: NRC Regulatory Guide
Document ID: 29acb072-d497-44e6-ac1c-a053c0a468a0
Document Type: regulatory_guide
Title: Meteorological Monitoring Programs for Nuclear Power Plants + HISTORY - HISTORY DG-1164 , Third Proposed Revision 1, published 10/2006 Draft ES 926-4 , Second Proposed Revision 1, entitled "Meteorological Measurement Program for Nuclear Power Plants," published 04/1986 Draft SS 926-4 , First Proposed Revision 1, entitled "Meteorological Programs In Support of Nuclear Power Plants," published 09/1980 Revision 0, entitled "Onsite Meteorological Programs," was issued as Safety Guide 23
Source: NRC Regulatory Guide Division 1
Source URL: https://www.nrc.gov/docs/ML0625/ML062540408.pdf
Revision Date: 2023-06
Chapter: 
Section ID: RG-1.23
CFR Part: 
CFR Title: 

Content:
1.145 and 1.194. Proposed Change Basis Appendix A to DG-1164, Page A-5 7. Add a criterion that precipitation should be measured at ground level near the base of the tower. Severe accident calculations now included in an applicant’s environmental report and the staff’s environmental impact statement use precipitation. 8. Clarify the definition of system accuracy, update some of the system accuracy criteria (e.g., add wind direction accuracy for time- average values, specify wind direction sensor starting threshold, decrease wind speed accuracy criteria for wind speeds $ 2.2 m/s, decrease dew-point accuracy criteria, add precipitation accuracy criteria) and specify measurement resolutions. The agency adopted much of this enhanced guidance from ANSI/ANS-3.11-2005. 9. Provide guidance that the tower and instrumentation should be capable of surviving, monitoring, and displaying any onsite meteorological conditions used as a basis for any emergency action levels. Where applicable, this change ensures that the meteorological monitoring system can effectively support providing the meteorological data that are used as a basis for any emergency action levels in accordance with 10 CFR 50.47(b)(4) and Section IV.B of Appendix E to 10 CFR Part 50. 10. Provide guidance on sampling frequencies and eliminate the criterion for redundant recorders. The agency adopted much of this enhanced guidance from ANSI/ANS-3.11-2005. 11. Update the specified format for wind speed, wind direction, and stability joint frequency distribution summaries and add a criterion that an electronic copy of the hourly database should be submitted with the application. This change adds a finer category breakdown for the lower wind speeds, which is an important input to the Regulatory Guide 1.145 atmospheric dispersion models. The NRC is moving the criterion to submit an electronic copy of the hourly database, already discussed in Standard Review Plan Section 2.3.3, into Regulatory Guide 1.23. 12. Clarify