Integrated Safety Assessment as an Instrument for Waste Acceptance Criteria Derivation The inventory and maximal specific activity of radionuclides are not the only but most significant parameters of Waste Acceptance Criteria (WAC) Safety Assessment (SA) is a necessary tool for derivation of waste acceptance criteria and for demonstration that derived values are safe. When considering disposal facility one should destinguish between Long-term (post-closure) Safety Assessment (LSA) and Operational Safety Assessment (OSA) Both LSA and OSA in general have similar structure and algorithm but scenarios, assumptions, models and instruments are different The main features affected the WAC as LSA results are the following: radionuclide half-life, mobility of each radionuclide, engineered and natural safety barriers retardation properties The main factors affected the WAC as OSA results are: Safety culture, RAW management system, number of workers and there qualification, presence of gamma-emitting radionuclides in the waste Stand alone long-term safety assessment or operational safety assessment are insufficient for derivation of such WAC parameters as the inventory and maximal radionuclide specific activity. Due to the same subject and potential contradictions in assumptions and models an integrated approach in using OSA and LSA for WAC derivation would be beneficial