Neutronics study for DTT tokamak building

The Divertor Tokamak Test (DTT) facility is a project proposed by an Italian consortium aimed to test the physics and technology of various alternative divertor concepts in order to design a heat and power exhaust system able to withstand the large loads expected in the divertor of a DEMO fusion power plant. The DTT machine is expected to produce up to 1.0 × 1017 2.5-MeV neutrons per second through deuterium-deuterium (DD) reactions with a significant 14 MeV neutron production (1% of the total yield) due to triton burn-up during the high-performance phase. This work is devoted to a preliminary three-dimensional shielding study to optimize the DTT building for licensing purposes. Neutron and gamma transport simulations were carried-out with MCNP5 Monte Carlo code using weight windows generated with ADVANTG hybrid code. Three-dimensional model of the DTT machine and building has been developed to assess the spatial distributions of the neutron and gamma fluxes, spectra and effective doses inside and outside the tokamak hall. The wall thickness (in the range 150–250 cm) has no impact on satisfying dose limits for the public, but is important when satisfying limits for workers.