Chernobyl case study increases confidence level in radionuclide transport assessments in the geosphere.
D. Bugai, L.Dewière*, V. Kashparov**, A.Skalskyy, S.Levchuk**, and V.Barthès***
Institute of Geological Sciences (IGS), Gonchara Str.55-b, 01054 Kiev, Ukraine
*Institute for Radioprotection and Nuclear Safety (IRSN), BP6, 92266 Fontenay aux Roses cedex, France
** Ukrainian Institute of Agricultural Radiology (UIAR), Mashinostroiteley Str.7, Chabany, Kiev Region, 255205, Ukraine
*** Atomic Energy Commission, DRT - DTN Section of Application of Tracers (SAT), 17, Rue des Martyrs, 38054, Grenoble cédex 09, France
Eurosafe Berlin 2002, 4/5 novembre
Results are presented from the ongoing international study (i.e., Chernobyl Pilot Site Project) on characterization and modeling of fallout nuclear fuel particles dissolution behavior and subsequent radionuclide transport from the near-surface waste disposai site in Chernobyl zone ta the geo-environment. The reported experimental work includes: - characterization of radionuclide physico-chemical speciation inside the waste site (trench); - evaluation of infiltration recharge regime through the trench body; and determination of waste soil matrix sorption parameters. In order to describe radionuclide releases from the waste, the multi-component source term model accounting for several types of fuel particles (UO2, UO2+x, and U-Zr-O matrix) was developed. Application of the source-term model to the Pilot Site data has given satisfactory and encouraging results. The modeling approach has proved to be capable of rather accurately reproducing independent field characterization and monitoring data relevant to 90Sr speciation inside the trench and radionuclide releases from the trench to the aquifer. The developed parameter database and modeling approach are of general value for radiological assessments of Chernobyl contaminated areas, and for possible similar accidental situations in future. Thus, acquired knowledge and data serve to increase the confidence level in radionuclide transport assessments from nuclear fuel source term to soils and geo-sphere.