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Performance assessment studies have been undertaken on the geological disposal of high-level waste in a clay layer in the framework of the CEC project PAGIS. The methodology applied consists of two consecutive steps : a scenario and a consequence analysis. The scenario analysis has indicated that scenarios of normal evolution, of human intrusion, of climatic change, of secondary glaciation effects and of faulting should be evaluated. For the consequence analysis as well deterministic “best estimate” as stochastic calculations, including uncertainty, risk and sensitivity analyses, have been elaborated.The calculations performed show that most radionuclides decay to negligible levels within the first fewjneters of the clay barrier. Just a few radionuclides, 99Tc, 135Cs and 237Np with its daughter nuclides 233U and 229Th can eventually reach the biosphere. The maximum dose rates arising from the geological disposal of HLW, as evaluated by the “best-estimate” approach are about 10−11 Sv/y for river pathways. If the sinking of a water well into the 150 m deep aquifer layer in the vicinity of the repository is considered together with a climatic change, the maximum calculated dose rate rises to a value of 3×10−7 Sv/y. The maximum dose rates evaluated by stochastic calculations are about one order of magnitude higher due to the considerable uncertainties in the model parameters. In the case of the Boom clay the estimated consequences of a fault scenario are of the same order of magnitude as the results obtained for the normal evolution scenario. The maximum risk is estimated from the results obtained through stochastic calculations to be about 5×10−8 per year. The sensitivity analysis has shown that the effective thickness of the clay layer, the retention factors of Tc, Cs and Np, and the Darcy velocity in the aquifer are parameters which strongly influence the calculated dose rates.

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The objective of the International Project on Innovative Nuclear Reactors and Fuel Cycles (INPRO) is to support the safe, sustainable, economic and proliferation resistant use of nuclear technology to meet the needs of the 21st century. The first part of the project focusses on the development of an understanding of the requirements of possible users of innovative concepts for reactors and fuel cycle applications. This paper reports progress made on the identification of user requirements as they relate to the environment and environmental protection. The user requirements being formulated are intended to limit adverse environmental effects from the different facilities involved in the nuclear fuel cycles to be well below maximum acceptable levels. To determine if the user requirements are met, it is necessary to identify those factors that are relevant to assessment of the environmental performance of innovative nuclear systems. To this effect, Environmental Impact Assessment (EIA) and the Material Flow accounting (MFA) methodologies are being appraised for the suitability for application. This paper develops and provides the rationale for the “users’ requirements” as they are currently defined. Existing Environmental Impact Assessment and Materials Flow Accounting methodologies that can be applied to determine whether or not innovative technologies conform to the User Requirements are briefly described. It is concluded that after establishing fundamental principles, it is possible to formulate sets of general and specific users’ requirements against which, the potential adverse environmental effects to be expected from innovative nuclear energy systems (INES) can be assessed. The application of these users’ requirements should keep the adverse environmental effects from INES’s within acceptable limits.

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