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Equipment and piping components contaminated by radioactive materials and/or containing low-level irradiated waste must be cut, segmented, and packed into waste containers. Workers need to avoid overexposure to radiation in dismantling environments, and the number of waste containers for the pieces of equipment and piping components needs to be minimized. Thus, we developed an automatic planning method for virtually cutting 3D equipment with limitations on container size, radioactivity, weight, and dose rate. Cutting sequence data was used to formulate different cutting-work procedures, generate cut objects, and calculate the exposure during disassembling work. By calculating the required cutting length and dose-rate distribution in working environments for various cutting sequences of large equipment, the developed system is expected to aid in the planning of decommissioning. To utilize systems engineering in conjunction with elemental technologies, the following problems need to be solved; both weight and volume of the waste need to be controlled so that radioactive waste for decommissioning nuclear power plants is traceable. Identifying segmented equipment from a 3D model is key to calculating the number of volumetric segmented fragments and required number of containers. To evaluate exposure and amount of waste, we developed an automatic planning method for virtually cutting 3D equipment objects given constraints. Cutting sequence data was used to formulate different cutting workflows, generate cut objects, and calculate the exposure dose from disassembling work.

There are no data available with regard to radon emanation coe‹cients for uranium-bearing wastes; such data are needed for the assessment of radiation exposure from radon that will be generated in the distant future as one uranium progeny at shallow land disposal sites for uranium-bearing wastes. There are many kinds of uranium-bearing wastes. However, it is not necessary to measure the radon emanation coe‹cients for all of them for two reasons. First, the radon emanation coe‹cients for uranium-bearing wastes contaminated by dissolved uranium are determined by the uranium chemical form, the manner of uranium deposition on the waste matrix, and the size of the particles which constitute the waste matrix. Therefore, only a few representative measurements are su‹cient for such uranium-bearing wastes. Second, it is possible to make theoretical calculations of radon emanation coe‹cients for uranium-bearing wastes contaminated by UO 2 particles before sintering. In the present study, simulated uranium-bearing wastes contaminated by dissolved uranium were prepared, their radon emanation coe‹cients were measured and radon emanation coe‹cients were calculated theoretically for uranium-bearing wastes contaminated by UO 2 particles before sintering. The obtained radon emanation coe‹cients are distributed at higher values than those for ubiquitous soils and rocks in the natural environment. Therefore, it is not correct to just compare uranium concentrations among uranium-bearing wastes, ubiquitous soils and rocks in terms of radiation exposure. The radon emanation coe‹cients obtained in the present study have to be employed together with the uranium concentration in uranium-bearing wastes in order to achieve proper assessment of radiation exposure.

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