Assessment of potential options for conditional reuse of materials from nuclear installation decommissioning

The nuclear installation decommissioning process is characterized by production of large amount of radioactive materials to be managed. The materials with radioactivity slightly above the unconditional release levels could be released conditionally for a specific industrial application in accordance with beforehand developed and evaluated scenario. This evaluation has to ensure that the limits for radiation exposure of workers and the public will not be exceeded. The paper gives an overview of representative options (scenarios) for reuse of conditionally released steel materials and recycled concrete from decommissioning. The main aim of the paper is to present the developed complex methodology for assessment of these options and its implementation to the relevant calculation tools. The first step in the methodology procedure is the identification of the activities which could lead to the exposure of the public or workers. For defined activities the external exposure of workers and the public is evaluated using the Visiplan 3D ALARA Planning tool. The internal exposure analysis is mainly based on the models for migration of radionuclides in the environment calculated in the GoldSim code. Based on the results of exposure evaluation, the critical exposure pathway is determined and conditional release levels of individual radionuclides are derived. Finally the amount and radioactivity of materials from decommissioning, fulfilling the limits for conditional reuse, are calculated in the decommissioning planning code OMEG