IDEA: An Integrated Set of Tools for Sustainable Nuclear Decommissioning Projects

Projects Decommissioning of nuclear installations constitutes an important challenge and shall prove to the public that the whole nuclear life cycle is fully mastered by the nuclear industry. When ceasing operation, nuclear installations owners and operators are looking for solutions in order to assess and keep decommissioning costs at a reasonable level, to fully characterize waste streams (in particular radiological inventories of difficult-to-measure radionuclides) and to reduce personnel exposure during the decommissioning activities taking into account several project, site and country specific constraints. In response to this need, Tractebel Engineering has developed IDEA (Integrated DEcommissioning Application), an integrated set of computer tools, to support the engineering activities to be carried out in the frame of a decommissioning project. IDEA provides optimized solutions from an economical, environmental, social and safety perspective. IDEA is based on the integration of the following computer tools: LLWAA-DECOM, VISIMODELLER/VISIPLAN and DBS. The LLWAA-DECOM module has been developed for the radiological characterization of contaminated systems and equipment. The module constitutes a specific part of more general software that was originally developed to characterize NPP radioactive waste streams in order to assist the Operators when declaring the radiological inventory of critical nuclides, in particular difficult-to-measure radionuclides, to the Authorities. In the case of LLWAA-DECOM, deposited activities inside contaminated equipment (piping, tanks, heat exchangers ...) and scaling factors between nuclides, at any given time of the decommissioning time schedule, are calculated on the basis of physical characteristics of the systems and of operational parameters of the nuclear power plant. The VISIMODELLER tool, a user friendly CAD interface developed to ease the introduction of lay-out areas in a software named VISIPLAN. VISIPLAN is a 3D dose rate assessment tool for ALARA work planning, developed by the Belgian Nuclear Research Centre SCK•CEN. The DBS computer tool has been developed to manage the different kinds of activities that are part of the general time schedule of a decommissioning project. For each activity, when relevant, algorithms allow to estimate, on the basis of local inputs, radiological exposures of the operators (collective and individual doses), production of primary, secondary and tertiary waste and their characterization, production of conditioned waste, release of effluents, ... and enable the calculation and the presentation (histograms) of the global results for all activities together. Based on design and operating data from the Nuclear Power Plant to be dismantled and on the specificities of the country regarding radioactive waste management and disposal routes, IDEA will enable to prepare and manage a decommissioning project, in a sustainable way, leading to a greenfield or a reuse of the nuclear site after decommissioning of the plant. Moreover thanks to the characterization and definition of the optimal waste treatment and conditioning techniques, IDEA contributes to the long term safe management of the radioactive waste.