Neutronic Analysis of the Fusion Reactor ARC: Monte Carlo Simulations with the Serpent Code

Neutronic modeling of fusion machines requires a detailed representation of their complex geometry in order to properly evaluate various parameters of interest such as energy deposition and tritium production in the breeding blanket. In this work, the neutronics of the Affordable, Robust, Compact (ARC) fusion reactor is modeled with the Monte Carlo particle transport code Serpent developed at VTT Technical Research Centre of Finland as an alternative to other, more established, tools in the fusion community such as the Monte Carlo N-Particle Transport (MCNP) code. The tritium breeding ratio (TBR) and the power deposited by neutrons and photons inside the breeding blanket of ARC are evaluated. Considerations related to activation of materials and to neutron shielding are not taken into account. As a first step, estimations have been obtained adopting a spatially uniform neutron source inside the plasma chamber. A second set of calculations has been performed considering a nonuniform source that takes into account a more realistic neutron generation distribution, with higher values at the center of the plasma and reduced rates toward the plasma edge. The results obtained with Serpent have been compared with available literature values for the TBR and the power deposition, confirming that Serpent can be considered a suitable alternative code for the neutronic analysis of fusion reactors like ARC. The TBR presented in this paper (1.0853) is in good agreement with the value found in the literature, with a relative difference of 0.49%. The total power deposition has a maximum relative difference of 12% for the components of interest in the present work.