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

NCRP Report No 123-I. NCRP, 1996. - 294 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 objective of this Report is to provide a series of simple screening techniques that can be employed to demonstrate compliance with environmental standards or other administratively-set reference levels for releases of radionuclides to the atmosphere, surface water or ground. The methods are designed primarily for facilities handling small quantities of radioactive materials released as point source emissions. However, these screening techniques can be employed by any facility releasing radionuclides to the environment, and modifications can be made to the current screening methodology to account for releases from area sources. Conservative models and parameters are proposed. if compliance with the limits can be demonstrated using these screening models, then more sophisticated modeling techniques are not necessary. **ContentsPreface****Atmospheric transport models** basic Screening Technique Basic Calculational Model Default Meteorological input Values **Surface water transport models** preliminary Screening Technique (Screening Level i) Surface Water Transport Models (Screening Level ii) **Disposal of radionuclides in ground—Assumptions and calculation of source term inventory** computational Method Screening Dose Calculations Discussion of Model Conservatism **Terrestrial transport models** calculation of Radionuclide Concentration in Vegetation Concentration of Radionuclides in Animal Products **Aquatic transport models Usage factors Dose factors and screening factors** derivation of Dose Factors Used to Develop Screening Factors Screening FactorsAppendix A. Effective Dose Factors Appendix B. Atmosphere Screening Factors Appendix C. Surface Water Screening Appendix D. Ground Screening Factors NCRP Report No 123-I. NCRP, 1996. - 294 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 objective of this Report is to provide a series of simple screening techniques that can be employed to demonstrate compliance with environmental standards or other administratively-set reference levels for releases of radionuclides to the atmosphere, surface water or ground. The methods are designed primarily for facilities handling small quantities of radioactive materials released as point source emissions. However, these screening techniques can be employed by any facility releasing radionuclides to the environment, and modifications can be made to the current screening methodology to account for releases from area sources. Conservative models and parameters are proposed. if compliance with the limits can be demonstrated using these screening models, then more sophisticated modeling techniques are not necessary. Contents Preface Atmospheric transport models basic Screening Technique Basic Calculational Model Default Meteorological input Values Surface water transport models preliminary Screening Technique (Screening Level i) Surface Water Transport Models (Screening Level ii) Disposal of radionuclides in ground—Assumptions and calculation of source term inventory computational Method Screening Dose Calculations Discussion of Model Conservatism Terrestrial transport models calculation of Radionuclide Concentration in Vegetation Concentration of Radionuclides in Animal Products Aquatic transport models Usage factors Dose factors and screening factors derivation of Dose Factors Used to Develop Screening Factors Screening Factors Appendix A. Effective Dose Factors Appendix B. Atmosphere Screening Factors Appendix C. Surface Water Screening Appendix D. Ground Screening Factors