AbstractThe reduced descriptions of the distribution of impurities over ionization states, radiation losses and plasma dynamics are reviewed. Two and three most important ion approximation for light impurities and continuous descriptions of heavy impurities are discussed. Reduced descriptions of atomic processes like ionization, photo‐ and dielectronic recombination rates as well as of radiation abilities are proposed. As it shown, thermal forces, final relaxation times of impurity distributions over ionization states, charge‐exchange and opacity effects must be taken into account in reduced models, especially for ITER problems. Linear and nonlinear stages of the radiation‐condensation mode as well as some aspects of disruptions and noble gas injection into tokamak plasmas are analyzed with the reduced models. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)