Document: NRC Regulatory Guide
Document ID: bd0ffb9e-22f8-46a4-ab36-f5cffd435ed7
Document Type: regulatory_guide
Title: Assumptions Used for Evaluating the Potential Radiological Consequences of a Loss of Coolant Accident for Boiling Water Reactors (Rev. 2)
Source: NRC Regulatory Guide Division 1
Source URL: https://www.nrc.gov/docs/ML0037/ML003739601.pdf
Revision Date: 2023-06
Chapter: 
Section ID: RG-1.3
CFR Part: 
CFR Title: 

Content:
ed to reduce the leakage of radioactive materials from the containment will be evaluated on an individual case basis. "2 In some cases, credit for mixing will be allowed; however, the amount of credit allowed will be evaluated on an individual case basis. ' Credit for an elevated release should be given only if the point of release is (1) more than two and one-half times the height of any structure close enough to affect the dispersion of the plume, or (2) located far enough from any structure which could have an effect on the dispersion of the plume. For those BWR's without stacks the atmospheric diffusion factors assuming ground level release given in section 2.h. should be used to determine site acceptability. 4 For sites located more than 2 miles from large bodies of water such as oceans or one of the Great Lakes, a fumigation condition should be assumed to exist at the time of the accident and continue for one-half hour. For sites located less than 2 miles from large bodies of water, a fumigation condition should be assumed to exist at the time of the accident and continue for 4 hours. developed from the average daily breathing rate [2 x 107 cm3 /day] assumed in the report of ICRP, Committee 11-1959.). d. The iodine dose conversion factors are given in ICRP Publication 2, Report of Committee II, "Permissible Dose for Internal Radiation," 1959. e. External whole body doses should be calculated using "Infinite Cloud" assumptions, i.e., the dimensions of the cloud are assumed to be large compared to the distance that the gamma rays and beta particles travel. "Such a cloud would be considered an infinite cloud for a receptor at the center because any additional [gamma and] beta emitting material beyond the cloud dimensions would not alter the flux of [gamma rays and] beta particles to the receptor" (Meteorology and Atomic Energy, Section 7.4.1.1-editorial additions made so that gamma and beta emitting material could be considered). Under these conditions the rate