Radiation Shielding of Fusion Systems

This thesis discusses the development, benchmarking and applications of activation dose analysis methods for fusion devices. The development and code logic of the Mesh Coupled Rigorous 2 Step (MCR2S) system is discussed. Following the development of the code, appropriate benchmarking studies were performed on the Frascati neutron generator, and revealed that the code was able to predict shutdown gamma ray doserates to within ±3% of experimentally determined values, for decay times between 3×105 and 107 seconds. The development of the Ion Cyclotron Resonance Heater (ICRH) with regards to neutronics was discussed. The ICRH went through a number of design stages and shutdown gamma ray dose rates were determined for each stage. It was determined that of all the designs analysed only one of them, the first concept design for the internally matched design did not meet the shutdown dose criteria. This was due to a flaw in the system design, brought about by a lack of consideration towards nuclear design. The ITER Light Imaging Detection and Ranging (LIDAR) system was subjected to a full shutdown nuclear analysis. It was found that the design of the LIDAR system supplied did not meet the ITER required shutdown gamma ray dose rate limit of 100 µSvhr−1, however use of the MCR2S system highlighted the components that contributed most to the shutdown gamma ray dose rate and were shown to be the mirror holder and the laser beam pipe. Future designs should include additional shielding around the beam pipe.