Document: NRC Regulatory Guide
Document ID: c992c9f8-7405-4a7c-afdc-b3d2a6922aad
Document Type: regulatory_guide
Title: Assumptions Used for Evaluating the Potential Radiological Consequences of a Steam Line Break Accident for Boiling Water Reactors
Source: NRC Regulatory Guide Division 1
Source URL: https://www.nrc.gov/docs/ML0037/ML003739923.pdf
Revision Date: 2023-06
Chapter: 
Section ID: RG-1.5
CFR Part: 
CFR Title: 

Content:
are used: 0.0133 (1) The dose at any distance from /Y the reactor is calculated based Where: on the maximum concentra- x = the short term aver tion in the plume at that dis- age centerline value tance taking into account of the ground level 4 Meteorology and Atomic Energy-1968, Chapter 7, From a semi-infinite cloud, the gamma dose "Radioactive Cloud-dose Calculations," lists the follow- rate in air is: D' = 0.25Efx. ing equations: Where: A. For an infinite uniform cloud containing x D beta dose rate from an infinite cloud curies of beta radioactivity per cubic meter (rad 'sec) the beta dose rate in air at the cloud center is: ,l)%. = gamma dose rate from an infinite aD'_ = 0.457 ERx cloud (rad/.ecl The surface body dose rate from beta emitters in the infinite cloud can be approximated as being one-half this amount (i.e., #D'. 0.23 kE',x B..For gamma er.:ting material the dose rate in air at the cloud center is: ..D', = 0.507 E..x 5.2 Ee =: average beta energy per disintegra tion (Mev /dis) E- - average gamma energy per disinte gration (Mev/dis) x : concentration of beta or gamma emit ting isotope in the cloud (curie/m3) concentration (cur ies/meter3 ) Q = amount of material released (curies/ sec) ay = the horizontal standard deviation of the plume (meters) [See Fig ure V-i, Page 48, Nuclear Safety, June 1961, Volume 2, Number 4, "Use of Routine Meteoro- logical Observations for Estimating At mospheric Disper sion," F. A. Gifford, Jr.] u = wind speed (meters /sec) (2) Figure 1 gives elevated release atmospheric diffusion factors assuming a release at thirty meters, and atmospheric con ditions assumed to be Pas quill F, windspeed 1 meter/ sec. 5.3 innn , I I I I JTI 1: All M 444-4 ## t:.'t H+A++ -F + + it :m 4044 3E JE ±H+ M AT to j f I 1 1 1 -FH- i + -AHQ4+: 7 i -44 014 i 1 H i + + + lull, im Tat It 1 +144 +'f+ 1ITT Of OR =1 I Ell TM I LLF IDT iLL= 01 Eff. 7 4 6 4 7 16 2 4 5 6 MUrM him FWvM PWat (nwim) 5.4