Screening Models for Releases of Radionuclides to Atmosphere, Surface Water, and Ground (Part II)

Description

NCRP Report № 123-II. NCRP, 1996. - 205 p. Mathematical models for estimating exposures to members of the public from radionuclides released to the environment have become increasingly sophisticated. However, when applying these models to assess the potential impact of radionuclide releases, it is recommended that the simplest model that will adequately address the problem always be applied first. The work sheets set out at the end of each section of this Volume are designed to lead the user through screening in a step-by-step manner until compliance is demonstrated or it is determined that more sophisticated methods or expertise are needed. It is recommended that copies be made of these work sheets for use in the screening process. It may also be helpful to copy the tables and figures that provide the information needed to do the work sheets. These are set out before the work sheets in each section in this Volume. Permission is granted to individual users to make copies of the work sheets herein for their personal use. In addition, a hand calculator will be needed. Flow diagrams are provided as a guide to identify key steps in the screening process. Example problems, included in Appendix A of this Volume should be reviewed prior to beginning a screening assessment. Working through the examples will demonstrate to the user how the procedure is to be followed and the various forms to be applied. The left-hand page of each work sheet explains the entry to be made in the blanks on the right-hand page. Basic to the screen calculation is the "screening factor." Screening factors represent the sum committed effective doses (Sv) received from external radiation over an assumed time period (less than 1 y), plus of inhalation of radioactive particles and gases, plus ingestion of locally grown foods during 1 у for a unit concentration of radioactivity (Sv per Bq m-3) in the medium, atmosphere or water. Ground screening factors are calculated as a dose per unit radioactivity of buried radioactive material (Sv Bq-1).Contents How to Begin Atmosphere Atmosphere Screening Level I: Vent Air Atmosphere Screening Level II: All Pathways Atmosphere Screening Level III: Specific Pathways Surface Water Surface Water Screening Level I: Radionuclide Release Surface Water Screening Level II: Dilution Calculations Surface Water Screening Level III: Screening Value Calculation Burial in Ground Appendix A. Example Problems A.1 Atmosphere Release Example Problems A.2 Surface Water Example Problem A.3 Ground Disposal Example Problems