Document: NUREG-0800
Document ID: 37e64905-5f3c-4221-9ce6-b3089b164d6f
Document Type: srp
Title: LONG-TERM DIFFUSION ESTIMATES
Source: NUREG-0800
Source URL: https://www.nrc.gov/docs/ML0520/ML052070237.pdf
Revision Date: 2023-06
Chapter: 2
Section ID: 2.3.5
CFR Part: 
CFR Title: 

Content:
sion Parameters The vertical plume spread parameter, , as a function of distance and atmospheric z stability is reviewed. Atmospheric stability should be defined by measurement of vertical temperature gradient, particularly during stable conditions. Other classification schemes (e.g., Refs. 10 and 11Refs. 11 and 12 ) may be used to estimate atmospheric 21 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 with z 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. 1213 ) and 22 large bodies of water (see Ref. 1314 ). 23 3. Meteorological Data Meteorological data are reviewed for compatibility with the models utilized, representativeness of conditions within the area of interest, and representativeness of annual average meteorological characteristics in the vicinity of the plant. General criteria for collection and presentation of onsite 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 ensure that adequate conservatism is 24 applied to prevent significant underestimates 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 80 km (50 mi) from the plant, as well as for specific 25 receptor locations. RAB provides theThe locations of specific receptors (e.g., site boundary,