Conditional release of materials from decommissioning process into the environment in the form of steel railway tracks Original Research Article

This work points to the possibilities of conditional release of materials from the process of decommissioning the nuclear unit from the operation. According to the valid legislation, materials which do not meet the condition of direct—unconditional release into the environment, should be modified and processed into the matrix designed for the final disposal in the storing place. However there exists a group of materials which activity is on the borderline of the limit of releasing into the environment and it is possible to release them conditionally. The matter of conditional release is that notable amount of materials, mainly metals, is usually contaminated only by radionuclids with relatively short time of half decay. These materials are suitable to use for a specific industrial purpose where the longtime fixation of shortly living radionuclids is expected in one place. This work deals with the conditional release of metals into the form of steel railway tracks. It describes the (working) groups of workers working with the steel railway tracks and defines in the numbers the critical group and its critical individual. For critical individual it dimensions the amounts of materials, which are possible to be released conditionally from one double-unit of the plant of the type VVER 440 V-230 which operation was ended on the regular basis. According to the calculations in the software VISIPLAN and OMEGA there is defined a number of released steel in such way that the internationally recommended rate of maximal effective dose for critical individual—10 μSv/year [IAEA, 2008. Managing low radioactivity material from the decommissioning of nuclear facility. Technical reports series no. 462] is not extended. In the final part there are compared the estimates of the costs of the decommissioning process with the application of conditional release and without it, which is directly reflected in the amount of saved costs and number of containers for surface disposal.