[en] National geological disposal programmes for high level and long lived waste are facing a double challenge: to develop technically sound and safe solutions for the long term management of the waste and to obtain a sufficiently broad societal and political base for the decisions leading to facility siting, construction, operation and closure. There is a general awareness that the challenges cannot be dealt with in an isolated manner. This rapporteur's review introduces and discusses some of the major issues and achievements in the national disposal programmes and in the international discussions, as identified from the papers in this session and other sources of information. The aim of the paper is to provide elements for further discussion in the panel discussion of Session IIIa. (author)

[en] Managing radioactive waste inventories is much like managing huge amounts of technical and scientific data. Most of these data are aimed at one common goal: the knowledge of the radiological and chemical contents of a radioactive waste package destined to be disposed of in a final repository. All calculations concerning the design of such a repository, be it performance assessments or safety evaluations or, quite plainly, its dimensions, require a whole range of data, the most important being the number of primary waste packages that will exist at the end of the nuclear program and their radionuclide contents and chemical composition. Assessing these data involves a lot of number crunching. The pillars of the knowledge of these data are twofold, namely an acceptance system and an inventory of radioactive waste. Both are part of the radioactive waste management system put in place by ONDRAF/NIRAS, the Belgian agency for radioactive waste and enriched fissile materials. This paper outlines the way the acceptance system interacts with the inventory of radioactive waste. It then focuses on the inventory itself, describing the methodology and giving some of the key results of the most recent inventory exercise completed in 2003. The final paragraph highlights the way this inventory is used as an integrated part of a low-level waste management system. (author)

[en] Clear international evolution from performance and safety assessments (dose and risk) to safety cases - a collection of arguments in support of the long term safety of a repository - better exploitation and presentation of the full range of arguments (quantitative and qualitative) - serving different audiences - predictions versus illustrations (bounding assessments) - multiple function system - Regulations are reflecting this evolution - further guidance needed - weighting of indicators and arguments in different time frames

[en] Here we report a new methodology for the quantitative analysis of radiocaesium retention in soils. Previously studies of radiocaesium in soils have foundered because K_D (solid-liquid distribution coefficients) values have been derived under conditions very different from those in situ. We show that in situ K_D values can be predicted from readily measurable soil properties, thus enabling information about the mobility of radiocaesium in soils to be reliably and easily obtained. These findings can be generally applied to a wide variety of soils. (author)

[en] The aims of the topical session are to: - Gather information on ongoing work in national programs to address the key questions (below) - To gain an overview of operational safety issues outside RWMC and assess the potential for knowledge transfer - Starting from the key questions, to define the challenges and issues that could be of interest to, and benefit from discussion by, IGSC - To assess the need for further IGSC work on this topic and, if so, to define the activities and time frames. Key questions were identified by IGSC in the PoW: - What are the main operational safety issues that have implications for long-term performance? (To what extent are the various practices and constraints legally required? What are the minimum mining requirements and practices that apply for safe operation of a deep repository? Are there separate safety cases for operational and long-term safety? If so, how are the links made?); - How do these constraints vary according to key aspects of the disposal system concept such as waste type, host rock, planned operational lifetime, etc.? - How does the stepwise design and optimisation process balance operational and post-closure safety constraints related to conventional hazards, engineering feasibility, radiation protection? (What practical measures can be (or have been) taken to address specific hazards or issues---i.e. selection of materials, design elements? How flexible must be the design to adapt to the constraints at different stages? What methodologies are used to identify, prioritise and track the various requirements? How are these considerations balanced? Are there 'trade-off's' that must be made between short-term and long-term safety?); - What lessons can be learned from other relevant industries (e.g., especially the mining industry), and what are the limits of transferability? Eight presentations were provided on national experience related to the key questions; an additional presentation was provided by AREVA to describe the perspective and possible relevant experience on operational safety in the mining industry. The presentations were: a. Canada: Balancing operational and long-term safety in OPG's L and ILW DGR design (H. Leung and P. Gierszewski, OPG); Canada: Operational safety issues in uranium mines: application to deep geological repository (B.R. Ravishankar, CNSC); b. France: Operational safety and conventional hazards in designing a HLW repository (B. Cahen, Andra); c. France: Balancing operational and post closure safety issues (P. Bodenez and G. Dandrieux, ASN; C. Serres, IRSN); d. Germany: Implications of pre-closure activities on the backfilling and sealing measures for the ERAM LLW (R. Mauke and J. Wollrath, Federal Office for Radiation Protection, BfS); e. Germany: Experience from developing an advanced safety concept for HLW disposal in rock salt (J. Krone, DBE Technology); f. US: Balancing operational risks and worker safety with long term repository benefits in the Yucca Mountain repository design (E. Smistad, DOE-YM); g. Finland: Experience from ONKALO (M. Snellman, Saanio and Riekkola Oy); h. Industry: Operational safety and radiation protection: practical experience in uranium mining (J-M. Marino, AREVA)