Document: NRC Regulatory Guide
Document ID: d1045e85-64b0-4a83-8450-067a4fcd130f
Document Type: regulatory_guide
Title: Atmospheric Dispersion Models for Potential Accident Consequence Assessments at Nuclear Power Plants + HISTORY –HISTORY 04/2014 – Periodic Review of Revision 1 – Reviewed with issues for future consideration 02/1983 – Reissued 02/1983 to correct page 1.145-7 (Rev. 1)
Source: NRC Regulatory Guide Division 1
Source URL: https://www.nrc.gov/docs/ML0037/ML003740205.pdf
Revision Date: 2023-06
Chapter: 
Section ID: RG-1.145
CFR Part: 
CFR Title: 

Content:
Accordingly, this guide provides an acceptable methodology for deter- mining site-specific relative concentrations (X/Q) and should be used in determining xJQ values for the evalua- tions discussed in Regulatory Guide 1.3, "Assumptions Used for Evaluating the Potential Radiological Conse- quences of a Loss of Coolant Accident for Boiling Water I For additional information concerning the bases for the regula- tory positions presented in this guide, see NUREG/CR-2260, "Technical Basis for Regulatory Guide 1.145." Reactors," and Regulatory Guide 1.4, "Assumptions Used for Evaluating the Potential Radiological Consequences of a Loss of Coolant Accident for Pressurized Water Reactors." A number of other regulatory guides also include recom- mendations for or references to radiological analyses of potential accidents. The applicability of the specific criteria discussed herein to these other analyses will be considered on a case-by-case basis. Until such time as generic guidelines are developed for such analyses, the methodology provided in this guide is acceptable to the NRC staff. The Advisory Committee on Reactor Safeguards has 1* been consulted concerning this guide and has concurred in the regulatory position. B. DISCUSSION The atmospheric diffusion2 models described in this guide reflect review of recent experimental data on diffu- sion from releases at ground level at open sites and from releases at various locations on reactor facility buildings during stable atmospheric conditions with low windspeeds (Refs. I through 6). These tests confirm the existence of effluent plume "meander" during low windspeed condi- tions and neutral (D) and stable (E, F, and G) atmospheric stability conditions (as defined by the temperature differ- ence (AT) criteria in Regulatory Guide 1.23, "Onsite Meteorological Programs," and provide bases for quantify- ing the effects of plume meander on effluent concentra- tions. Effluent concentrations measured over a period of I hour under such