Migration of Radionuclide through Two-Layered Geologic Media

• Published in: Journal of nuclear science and technology Vol. 21; no. 2; pp. 139 - 147
• Main Authors: NAKAYAMA, Shinichi, TAKAGI, Ikuji, NAKAI, Kunihiro, HIGASHI, Kunio
• Format: Journal Article
• Language: English
• Published: Tokyo Taylor & Francis Group 01.02.1984; Atomic Energy Society of Japan; Taylor & Francis Ltd
• Subjects: accuracy; analytical solution; decay chains; discharge rate; Earth sciences; Earth, ocean, space; Engineering and environment geology. Geothermics; Exact sciences and technology; geologic disposal of HLW; granite; ingestion hazard index; interlayer boundary; Isotope geochemistry; Isotope geochemistry. Geochronology; radionuclide migration; soil; two-layered geologic media; Radioactive waste; Soils; Radioactive isotopes; Mathematical models; Migration of elements; Two-layer models; Granites
• ISSN: 0022-3131; 1881-1248
• DOI: 10.1080/18811248.1984.9731025

For the safety assessment of geologic disposal of high-level radioactive wastes, an analytical solution was obtained for one-dimensional migration of radionuclide through two-layered geologic media without dispersion. By applying it to geologic media composed of granite and soil layers, the effect of interlayer boundary on the discharge profile of radionuclides in decay chains into biological environment is examined. The time-space profiles of radionuclides in the vicinity of interlayer boundary are much complicated as shown in the results of calculation. Those profiles in case that the groundwater flows through granite followed by soil are quite different from those in case that the groundwater flows through soil followed by granite. Each of complicated dependence of profiles on time and space can be physically explained. The characteristic profiles in the vicinity of interlayer boundary have not been discussed previously. Recently, numerical computer codes has been developed to apply to much more realistic geologic situations. However, the numerical accuracies of the codes are necessary to be confirmed. This is achieved by comparing computational results with results from analytical solutions. The analytical solution presented will serve as a bench-mark for numerical accuracy.