Calculation of distribution coefficients for Radionuclides in soils and sediments
- Studsvilk Eco and Safety, Nykoping (Sweden)
The turnover of radionuclides in parts of the biosphere is usually modeled by use of a sorption distribution coefficient, K{sub a}. Its value has a large influence on calculated concentrations of long-lived radionuclides found in reservoirs, which are important for doses to humans. Sorption is due to several processes and a variety of physical and chemical interactions (e.g., surface complexation and ion exchange). In the commonly used K{sub d}-methodology, however, these processes were usually not considered explicitly. Additionally, many K{sub d} values were obtained from laboratory experiments or from the geosphere, the conditions of which differ from those prevailing in the biosphere. The main objective of this work was to extend the knowledge about the theoretical background for calculation of K{sub d} values. To achieve this objective, theoretical models for ion exchange and surface complexation were adapted to simulation under biospheric conditions. Elements studied were Cs, Ra, Np, U and Pu. The results show that a triple-layer surface complexation model may be used to estimate K{sub d} values for actinides as functions of some chemical parameters, such as pH and the redox potential (E{sub H}). An area of application is performance assessment of radioactive waste repositories.
- Research Organization:
- Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
- OSTI ID:
- 103244
- Report Number(s):
- TPJ-NS-36-No.1; TRN: 95:019860
- Resource Relation:
- Other Information: PBD: 1995; Related Information: Is Part Of Nuclear Safety Technical Progress Journal, January--June 1995. Volume 36, No. 1; PB: 199 p.
- Country of Publication:
- United States
- Language:
- English
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