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:
ncy that will ensure data recovery of at least 90 percent on an annual basis.9 The 90-percent rate applies to the composite of all variables (e.g., the joint frequency distribution of wind speed, wind direction, stability class) needed to model atmospheric dispersion for each potential release pathway. In addition, the 90-percent rate applies individually to the other meteorological parameters. Channel operability checks should be performed daily and channel calibrations should be performed semiannually, unless the operating history of the equipment indicates that either more or less frequent calibration is necessary. System calibrations should encompass entire data channels and may be performed by a series of sequential, overlapping, or total channel steps such that each channel from sensors to recorders and displays is calibrated. Where applicable, guyed wires and anchors used to support guyed towers should be inspected annually. 6. Data Reduction and Compilation Meteorological monitoring systems should use electronic digital data acquisition systems as the primary data recording system. Data may be recorded and displayed in either English units (e.g., miles per hour, degrees Fahrenheit, inches) or metric units (e.g., meters per second, degrees Celsius, millimeters) and should meet the resolution criteria listed in Table 2. 10 For those sites with a high frequency of low wind speeds, the joint frequency distributions of wind speed, wind direction, and atmospheric stability data should have a larger number of wind speed categories at the lower wind speeds to avoid having all the data listed in the lowest wind speed classes. 11 For example, if the comparison of the primary and supplemental meteorological systems indicates convergence in a lake breeze setting, then a “keyhole” protective action recommendation may not be appropriate. DG-1164, Page 11 A backup recording system (either analog or digital) may be used to provide a high assurance of valid data. Where