Heat Deposition And Temperature Distribution In The SEAFP Fusion Reactor Biological Shield

The European Safety and Environmental Assessment of Fusion Power (SEAFP-2) program deals with safety studies for power reactor designs. In the project, the cryostat, which acts also as a biological shield, consists in a 2,5 m thick concrete layer. In this paper, heat deposition on the cryostat/biological shield due to neutron and gamma fluxes during reactor operation has been calculated. It is the result of a discrete ordinates neutronic model of the reactor. It can be verified that the radial attenuation of the heat deposition is the dominant component. Temperature distribution in the cryostat during reactor operation has been computed. The relatively simple geometry of the component and the simple heat deposition function expression permitted to analitically solve the problem. It turns out that boundary conditions have a relevant influence on the temperature peak height and position, and a parametric study is performed. Temperature peaks in concretes used for biological shields in nuclear reactors should not exceed certain limits, in order to avoid possible degradation of the material properties. It turns out that, for SEAFP, the temperature limits for the reference concrete are not exceeded. A comparison with the heat deposition and temperature distribution calculation for a fission reactor is finally carried out, putting in evidence similarities and discrepancies.