The work is aimed at development of the technique of calculating radionuclide precipitation in reactor facilities with different heat carriers. A physical model of precipitation is developed, conditions of precipitation simulation are determined; calculated dependences are received for radionuclide concentration fields and precipitation coefficients. A technique of calculating radionuclide precipitation is developed, RADON computation program is created. Radionuclide precipitation is calculated for reactor plant AST-200 using RADON program. An increase of APP radiation sefety was observed. The field of application covers design and use of APP with different heat carriersAvailable from VNTIC / VNTIC - Scientific & Technical Information Centre of RussiaSIGLERURussian Federatio