Shutdown dose rate analyses for the IFMIF HFTM

Abstract

This work contributes to neutronic support activity for the high flux test module (HFTM) designing in the framework of the IFMIF/EVEDA project. The engineering design of the IFMIF maintenance and remote handling systems is significantly affected by the radiation doses originating from radioactive materials generated during operation in the IFMIF HFTM. Two aspects of shutdown doses have been analyses for the HFTM radioactive materials removed from the IFMIF target and test cell (TTC) and then placed into the hot cell. First aspect is machine reliability expressed through absorbed gamma dose rate in the envisaged radiation-sensitive silicon-based electronics located closely to the radioactive HFTM materials. Second one is radiation protection and safety of a human being presented quantitatively as human biological dose equivalent rate around the HFTM materials. Shutdown dose rate assessments were performed for different materials subjected to the radiation by decay photons emitted from the HFTM. Three different decay radiation sources were considered in the analyses: a simple Eurofer specimen, a single HFTM rig packed with specimens and an assembly consisting of 12 rigs. The shutdown dose rate has been assessed taking into account transport of decay gammas by means of subsequent use of three computer codes: McDeLicious, FISPACT-2007, and MCNP5.