Dissolution kinetics of particles of irradiated Chernobyl nuclear fuel: influence of pH and oxidation state on the release of radionuclides in the contaminated soil of Chernobyl

The radioactive contamination in the exclusion Chernobyl zone is mainly due to fuel particles present on the ground. Dissolution of these particles ca uses leaching of radionuclides to increase with time. The kinetics of disso lution of Chernobyl fuel particles were determined in solutions of differen t acidities, using material obtained by crushing actual irradiated Chernoby l fuel and by its oxidation for 1-21 h in air at a temperature of 670 K. Ox idation results in superficial cracking of the particles and an increase in their surface area and, therefore, higher dissolution rates for such parti cles than for non-oxidised ones. Dissolution rate of fuel particles increas es in acid and alkaline mediums. The dissolution rates obtained for non-oxi dised and oxidised fuel particles (UO2+x) in solutions of different aciditi es call be used as a basis for narrowing the scope of assessments for progn osis of changes in the radiological situation in the Chernobyl zone. (C) 20 00 Elsevier Science B.V. All rights reserved.