[en] Assessments of risk to the population and impact on the environment are performed as part of the licensing and standard setting process. Those assessments include evaluation of the effects of normal operation on the general population and occupationally exposed workers, consequences of potential adversary actions which may lead to damage of facilities and release of radionuclides into the environment. Generally, the data needed to perform realistic risk assessments include: knowledge of chemical and physical form of materials which may enter the environment; reliable models for predicting the physical transport, dispersion and deposition of materials in the environment confirmed by experiment and supported by their associated data base; methodology for reliably predicting cycling of radionuclides in ecological systems and the critical pathways whereby they may reach man; long-term environmental behavior and fate of radionuclides; chemical form and physiological availability of materials that may reach humans; bioaccumulation and retention of radioactive materials by human beings; dose conversion factors for inhaled and ingested materials; and dose-response relationships for the health effects of radionuclides ranging from long-term effects of low doses applied over long times to early mortality and morbidity resulting from short-term inhalation or ingestion of relatively large amounts