Document: NUREG-0800
Document ID: bb1a5a83-5b12-456c-b141-1e450c066cff
Document Type: srp
Title: ONSITE METEOROLOGICAL MEASUREMENTS PROGRAM
Source: NUREG-0800
Source URL: https://www.nrc.gov/docs/ML1818/ML18183A446.pdf
Revision Date: 2023-06
Chapter: 2
Section ID: 2.3.3
CFR Part: 
CFR Title: 

Content:
osure of Instruments The local exposure of the wind and temperature sensors is reviewed to ensure that the measurements represent the general site area. A determination is made as to whether the tower that supports the sensors will influence the wind or temperature measurements. Professional experience and studies have shown that wind sensors should be mounted on booms such that the sensors are at least two tower widths away from an open-latticed tower. For temperature sensors, mounting booms need not be as long as those for wind sensors but must be unaffected by thermal radiation from the tower itself. No wind or temperature sensors may be mounted directly on stacks or closed towers. Mounting booms for all sensors should be on the upwind side of the mounting object in areas with a dominant prevailing wind direction. In areas with two distinct prominent wind directions (such as mountain valleys), the sensors should be mounted in a direction perpendicular to the primary two directions to minimize tower interference. The staff should determine to whether the terrain at or near the base of the tower will unnaturally affect the wind or temperature measurements. Heat reflection characteristics of the surface underlying the meteorological tower (grass, soil, gravel, paving, etc.) are considered to ensure that localized influences on measurements are minimal. The position, size, and materials used in the construction of the instrument shelter and nearby trees and vegetation are also examined for potential localized influence on the measurements. (2) General Exposure of Instruments Since the objective of the instrumentation is to provide measurements that represent the overall site meteorology without interference from plant structures and other features, including plant operations, the positions of the primary and, if applicable, backup meteorological towers should have been selected with this general objective in mind. Examination of topographical maps, that have been