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
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CFR Title: 

Content:
evaluations, and support emergency preparedness programs and other applications at power reactor sites. 1. Definitions Calm: Any wind speed below the starting threshold of the wind speed or direction sensor, whichever is greater. Dew Point: The temperature to which a given parcel of air must be cooled at constant pressure and constant water-vapor content in order for saturation to occur. Gaussian Plume Model: A basic atmospheric dispersion model that assumes that the plume spread has a Gaussian distribution in both the horizontal and vertical directions and, therefore, uses the standard deviations of plume concentration distribution in the horizontal (σy) and vertical (σz). Precipitation: Any of the forms of water particles, whether liquid or solid, that fall from the atmosphere and reach the ground. Relative Humidity: The ratio of the vapor pressure to the saturation vapor pressure with respect to water. Pasquill Stability Class: A classification of atmospheric stability, or the amount of turbulent mixing in the atmosphere and its effect on effluent dispersion. Starting Threshold: The minimum wind speed above which the measuring instrument is performing within its minimum specification. System Accuracy: The amount by which a measured variable deviates from a value accepted as true or standard. System accuracy encompasses all the components of the system, from sensors through processors, data recorders, and displays. System Calibration: The process of validating the output of an observing system against known reference observations or standards. Temperature: A measure of the hotness or coldness of the ambient air as measured by a suitable instrument. Vertical Temperature Difference (∆T): The measured difference in air temperature between two elevations on the same tower. It is defined as the upper level temperature measurement minus the lower level temperature measurement. Water Equivalent: The amount of water, in inches, measured at ground level from rain