Document: NRC Regulatory Guide
Document ID: 14983af3-17d8-4f7b-866e-8d603a0f811c
Document Type: regulatory_guide
Title: Assumptions Used for Evaluating the Potential Radiological Consequences of a Loss of Coolant Accident for Pressurized Water Reactors (Rev. 2)
Source: NRC Regulatory Guide Division 1
Source URL: https://www.nrc.gov/docs/ML0037/ML003739614.pdf
Revision Date: 2023-06
Chapter: 
Section ID: RG-1.4
CFR Part: 
CFR Title: 

Content:
equation is: 2.032 x/Q = uu OzU Where x = distance from point of release to the receptor; other variables are as given in g(l). (3) The atmospheric diffusion model 2 for ground level releases is based on the information in the following table. 2 This model should be used until adequate site meteorological data are obtained. In some cases, available information, such as meteorology, topography and geographical location, may dictate the use of a more restrictive model to insure a conservative estimate of potential offsite exposures. Time Following Accident Atmospheric Conditions 0-8 hours Pasquill Type F, windspeed 1 meter/see, uniform direction 8.24 hours Pasquill Type F, windspeed 1 meter/sec, variable direction within a 22.50 sector 1-4 days (a) 40% Pasquill Type D, windspeed 3 meter/sec (b) 60% Pasquill Type F, windspeed 2 meter/sec (c) wind direction variable within a 22.50 sector 4-30 days (a) 33.3% Pasquill Type C, windspeed 3 meter/sec (b) 33.3% Pasquill meter/sec (c) 33.3% Pasquill meter/sec (d) Wind direction 22.50 sector Type D, windspeed 3 Type F, windspeed 2 33.3% frequency in a (4) Figures 2A and 2B give the ground level release atmospheric diffusion factors based on the parameters given in g(3). D. IMPLEMENTATION The revision to this guide (indicated by a line in the margin) reflects current Regulatory staff practice in the review of construction permit applications; therefore, this revision is effective immediately. 1.4-3 0 [-v _T_ ,- .44 -4 Rat -4- F-I H 1--r H:, 1 ifif- ---- T -T 77 -- ---- -- IW1ETýý T f-V 4 F I I F *1 - i I I '- cli a' K -4 F I 'I -.T- 71 * :1 * I KY ----9 -t -t -.. "'III' ii F.V-~2 H 4~~~t 1- 4r~4 7.~I J:r __________________ ___414_____1___ +1j -T4 LltIIII]I4J---I-1 1V w#tThJ 11ff -14- - :4Ij4Th1 - i-i 0 W4 BUILDING WAKE DISPERSION CORRECTION FACTOR 1' * Lr - Lii ilL- I U I I I..' -I ýff HT q--- *--7- -7 7- -+~1*~ 7 17. . . . . . .A . . . . . . . . . . . . . Ii -w 7---- -T 7- 1-ý 4 Lt.] -i-v-ti-ti r-i 4 T I' I' .10-40