Speaker
Description
The Divertor Tokamak Test (DTT) facility will be constructed at the ENEA Frascati Research Centre to address the problem of power exhaust, one of the key challenges of the future fusion power plants. DTT is a medium-sized superconducting tokamak operating with a deuterium plasma and with a substantial level of external heating power, to reproduce the divertor heat loads foreseen for ITER and DEMO. During the high-performance phases, DTT will produce 3∙10$^{22}$ neutrons per year (1.5∙10$^{17}$n/s) from D-D fusion reactions. In addition, the generation of a non-negligible amount of 14 MeV neutrons from D-T reactions is expected due to the triton burn-up. As a consequence, the machine components will be exposed to an intense neutron and gamma irradiation, as well as a high neutron-induced activation. This has a significant impact on the design of the tokamak components, auxiliary heating and diagnostics systems, as well as on licensing, maintenance, decommissioning and waste management.
In this work an overview of the neutronics studies supporting the DTT design will be reported, with a focus on two particular aspects, the impact of material impurities and the development of a detailed neutronics model. Some components are currently being put out to tender, and challenges may arise during manufacturing. These include inconsistencies in requirements flow-down, the need to rely on commercial off-the-shelf and standard components made from uncertified materials, the lack of established testing methods and protocols, and the increased costs and management complexity associated with certified purpose-built materials. To better address these issues, sensitivity studies have been carried out to assess how the increase in material impurity levels affects shutdown dose rate and radiological impact on working environment and personnel. A novel DTT neutronics model is under development by the neutronics team to enable a high-fidelity description of the components following the finalization of the DTT design. The development of the DTT neutronics model will be presented, also in the light of a parallel implementation of MCNP and OpenMC models.
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