Document: NUREG-0800
Document ID: 112961d5-bbf7-4ebc-8a51-ee8e2292ddbc
Document Type: srp
Title: LONG-TERM DIFFUSION ESTIMATES
Source: NUREG-0800
Source URL: https://www.nrc.gov/docs/ML0523/ML052340585.pdf
Revision Date: 2023-06
Chapter: 2
Section ID: 2.3.5
CFR Part: 
CFR Title: 

Content:
. Other classification schemes (e.g., Refs. 9 and 10) may be used to estimate atmospheric stability class or to determine the plume spread parameter directly for unstable and neutral conditions. These alternative classification schemes are reviewed for appropriateness to site, plant, and release characteristics. Standard curves of az with distance are presented in Regulatory Guide 1.111. Modified plume spread parameters may also be considered for unique terrain features such as deserts (see Ref. 11) and large bodies of water (see Ref. 12). 3. Meteorological Data Meteorological data are reviewed for compatibility with the models utilized, representativeness of conditions within the area of interest, and representa- tiveness of annual average meteorological characteristics in the vicinity 2.3.5-3 Rev. 2 - July 1981 of the plant. General criteria for collection and presentation of oi. meteorological data are stated in Regulatory Guide 1.23 and in SRP Section 2.3.3, subsection III.2. If adequate onsite meteorological data are not available, the reviewer must assure that adequate conservatism is applied to prevent signficant understimates of airborne concentrations and amount of material deposited. 4. Relative Concentrations Used for Routine Releases The X/Q and D/Q values used for assessment of the consequences of routine .radioactive releases are reviewed for appropriateness to site conditions, plant configuration, and release characteristics. Annual average X/Q and D/Q values are calculated for 16 radial sectors from the site boundary to a distance of 50 miles from the plant, as well as for specific receptor locations. RAB provides the locations of specific receptors (e.g., site boundary, residence, garden, cow). Adjustments of the X/Q and DIQ output may be necessary to relfect con- sideration of unusual site and/or meteorological conditions. Annual average X/Q and D/Q values at the specified receptor locations and at standard distances in the 16 radial sectors from