TABLE OF CONTENTS The final evaluation of any waste management concept is done using safety assessment (SA) and performance assessment (PA) cases. SA of nuclear waste disposal evaluates the repository performance and its radiological impact on the environment and humans. SA results in data demonstrating either compliance with safety standards or unacceptability of the proposed concept. PA provides data on the performance of all repository subsystems and the repository itself. PA results in data which are used to improve the overall safety and to demonstrate compliance with safety standards and performance targets. PA comprises scenario development and potential impact calculations. As a rule, the impact is characterised by the most probable doses arising from radionuclides which may be released and interact with the biosphere. Scenarios considered are not limited to the most probable but also include abnormal events. Mathematical models are key components of the SA and PA of waste disposal. A chain of mathematical models is used to describe the long-term degradation of the engineered barriers and the eventual release of radionuclides into ground water and their transport to the biosphere. All studies to date have shown that disposal of radioactive waste including geological disposal, can be safe; adequate isolation from the environment can be assured for hundreds of thousands of years and, thereafter, radionuclide releases are negligible in comparison to natural radiation exposures.
A fundamental requirement of all disposal practices is that they comply with the IAEA principles of radioactive waste management (see...
