In the past uranium mining and processing was often carried out in complete disregard for elementary rules of occupational safety and environmental protection,including the radiological hazards to humans and the environment.As a consequence existing exposure situation were left behind which required the management of large volumes of materials with elevated concentrations of natural radionuclides.Although uranium production residues are not considered as "classical" NORM (naturally occurring radioactive materials),in existing exposure situations both the management of uranium production legacies as well as the management of large amounts of NORM require the sound application of the ICRP key radiation protection principles for existing situations.An outstanding example for an existing exposure situation resulting from large-scale uranium mining and processing is the WISMUT legacy in East Germany.From 1946 to 1990 the Soviet-German stockholding company SDAG WISMUT produced 216.000 metric tons of uranium and became with it the worlds fourth largest uranium producer at that time.Due to the mining of low grade ore,about 800 Million tons of low-level radioactive waste was deposited at the sites and an area of about 10000 km2 became seriously affected and devastated.Unlike most uranium mining and milling operations in Canada,the United States and Australia,WISMUTs mining and milling facilities were located in a densely populated area,whereby radioactive waste rock piles and tailings management facilities were placed close to residential areas,in some cases immediately neighboring dwellings.In such an existing situation,the application of the ICRP key radiation protection principles and the implementation of the IAEA Basic Safety Standards have to meet site-specific conditions and require remedial measures which are far from standard solutions.This is illustrated in the present paper by the case study WISMUT.Approaches to decide on justification of remedial activities are presented together with optimization procedures.Thereby,special emphasize is given to the management of elevated radon concentrations at the sites.The implication of the most recent ICRP recommendations,as for instance the recommendations on work with and communication of reference values,on radon,on radiological protection of the environment and on stakeholder involvement,are evaluated for the WISMUT Environmental Rehabilitation Project.