Shutdown dose rate assessment with the Advanced D1S method for the European DCLL DEMO

The present paper is devoted to the shutdown dose rate assessment, one of the most important safety issues in fusion power plant design and operation. The characterization of the radiation environment after the shutdown is fundamental to plan safe operation and maintenance in a fusion machine in order to guarantee the dose limits are not exceeded. In this paper the shutdown dose due to the radionuclides generated by neutron activation of reactor components have been assessed for the design of the European DCLL v3.0 developed during 2016 integrated into the generic DEMO baseline 2015 fusion reactor. The shutdown dose rate calculations from 1 day to 1 year after shutdown have been performed through the Advanced D1S method coupling the particle transport MCNP5 and ACAB inventory codes. 3D maps of shutdown dose rates, decay fluxes for the whole reactor and decay gamma heating for Eurofer structures have been provided as well as specific values at relevant positions. Results are presented and discussed also in terms of the different nuclides contributions from the various activated components. Two different divertor compositions have been also used demonstrating the importance of this component not only locally but in the global radiation field inside the plasma chamber.