Recycling and reuse of very low level radioactive steel in motorway tunnel scenario

Abstract

Since a number of nuclear power plants are approaching the end of their lifetime is continuously increasing, decommissioning issues and radioactive waste management have become widely discussed topics. Considerable amounts of materials arising from decommissioning could be categorized as very low level radioactive waste. In line with international incentives for optimization of radioactive material management, alternative concepts of recycling and reuse of materials are suggested, analyzed and discussed. One of these concepts of such optimization is the conditional clearance of materials with their subsequent recycling and reuse in the industrial sector. The present paper describes an option of recycling and reuse of conditionally cleared steel in motorway tunnels.The analyzed scenario assumes that very low level radioactive steel would be reused in the form of steel reinforcing components, such as reinforcing mesh and bars, assembled in the primary and secondary linings of a motorway tunnel.However, prior to real application, a radiological impact assessment has to be done in order to prove compliance with radiation protection criteria. Methodology for implementation of the concept of conditional clearance was created and applied on two selected NPPs located in the Slovak Republic, which are currently under decommissioning. Assessment of relevant exposure pathways, which are likely to occur in the analyzed scenario, was performed.The aim of the paper is to derive and to justify new clearance levels for each radionuclide contained in steel reinforcement components in order to reuse the maximum amount of very low level radioactive steel considering radiation protection criteria. An increase of recyclable amount of radioactive steel could bring benefits in the form of saving considerable financial resources.