Neutronics on inertial fusion reactors

Neutrons produced in conceptual high gain targets of inertial fusion (IFE) reactors can contribute to the dynamics of the DT fuel burnup, and will emerge after some slowing down in the capsule with an energy spectrum depending on the target design and burnup conditions. Analysis of such spectra has been performed for different direct-drive target designs and ρR, and the time-dependent emission and arrival to the first wall of the system are reported. On the basis of established reactor designs (first variable to be considered) such as HIBALL-II or KOYO, the realistic possibility to obtain an uniform power distribution and obtain enough tritium breeding can be demonstrated. Activation of steels, vanadium alloys and SiC based composites has been considered in comparative analysis using different neutron energy spectra showing the important energy-dependent effect and the general advantages of V-alloys and SiC composites. The correct simulation of chains leading to radiological critical isotopes (function of neutron energy) and the goodness of nuclear data are essential for final responses/conclusions, and they need to be evaluated with careful uncertainty analysis. The damage accumulation because of very intense pulsed neutron fluxes in IFE reactors needs to be well understood prior to consideration of the availability of use of some very extensively considered low-activation materials. Results on simulations performed on SiC using an accumulated dose of 2×1014 recoi1s cm−2 are discussed and future work planned. Activation and damage analysis will impose clear boundaries in the final design of the reactor, and the availability in IFE power plants to include liquid protections to the walls is certainly very important.