Recent technical progress in fusion research has been sufficient to encourage the development of conceptual designs for fusion power systems. These design efforts suggest that more attention should be paid to the safety and environmental effects of the radioactivity induced in the structural materials by the fusion neutrons. In particular, radioactivity from neutron activation of the structural components of a fusion power system will be a concern for occupational exposure of personnel. Careful choice of structural materials can significantly reduce this exposure. We propose the Remote Maintenance Rating (RMR) as a numerical means of comparing materials and machine designs with respect to occupational exposures. The RMR is defined as the dose rate at the surface of a uniformly activated, thick, infinite slab with the same composition and density as the machine component. We used the RMR rating system to evaluate the suitability of several different iron-based alloys. The specific fusion power system design used in our evaluation was a conceptual design from the Mirror Advanced Reactor Study (MARS). We determined that HT-9 is significantly better in terms of radiological dose rates at early times than the other iron-based alloys (by a factor of 3 to 7). We also calculated the …

The basic equations of radiation hydrodynamics are discussed in the regime that the radiation is dynamically as well as thermally important. Particular attention is paid to the question of what constitutes an acceptable approximate non-relativistic system of dynamical equations for matter and radiation in this regime. Further discussion is devoted to two classes of application of these ideas. The first class consists of problems dominated by line radiation, which is sensitive to the velocity field through the Doppler effect. The second class is of problems in which the advection of radiation by moving matter dominates radiation diffusion.