Document: NUREG-0800
Document ID: dc7fdaed-8abd-4b49-b5df-dcf64a9b93b0
Document Type: srp
Title: SHORT-TERM DISPERSION ESTIMATES FOR ACCIDENTAL ATMOSPHERIC
Source: NUREG-0800
Source URL: https://www.nrc.gov/docs/ML0520/ML052070235.pdf
Revision Date: 2023-06
Chapter: 2
Section ID: 2.3.4
CFR Part: 
CFR Title: 

Content:
persion model described in Regulatory Guide 1.145. Modifications based on specific studies under similar conditions may also be considered to better represent plume spread over unique terrain features such as deserts (Ref. 1213 ) and large bodies of water (Ref. 1920 ). 23 24 For situations where a puff diffusion equation is used, = is usually a good x y assumption. DRAFT Rev. 2 - April 1996 2.3.4-6 4. Cumulative Frequency Distributions of X/Q The cumulative probability distributions of X/Q are reviewed for inclusion of pertinent modes and time periods of release, and adequacy of input data in accordance with the guidelines set forth in Section 2.3.4.2 of the Standard Format (Ref. 11)Regulatory Guide 1.70. The methods used to generate these distributions are reviewed for adequacy and 25 conservatism. For standard design certification reviews, site-related parameters, including values of X/Q, should be identified in the site parameter envelope. The specified values should be representative of credible, bounding characteristics. The reviewer verifies that the values of X/Q in the site parameter envelope are consistent with the acceptance criteria given in subsection II of this SRP section. For an application referencing a certified standard design, the reviewer verifies that measured site-related meteorological parameters for the proposed site have been used to derive site-specific X/Q values and that these values are consistent with those identified in the site parameter envelope for the certified design.26 5. Relative Concentrations Used for Accidents The X/Q values used for assessment of consequences of atmospheric radioactive releases for design basis accidents and other accidents, and for onsite and offsite releases of hazardous airborne gases are reviewed for appropriateness of atmospheric dispersion model assumptions and input data, and adequate documentation of this information. The staff makes an independent evaluation of atmospheric dispersion for pertinent