Deuterium and Tritium dynamic management in the Sorgentina-RF plant

In the medical field, diagnostic techniques are a fundamental method used to help diagnose a disease or condition. The single photon emission computed tomography (SPECT) is a diagnostic technique that covers more than 80% of all the nuclear medicine diagnostic procedures worldwide. One of the tracers used for it is 99mTc, generated by radioactive 99Mo. This radionuclide is produced irradiating uranium samples with neutrons generated in fission reactors, thus producing fission products and chemically separating molybdenum from the rest. Within this frame, Sorgentina-RF project aims to design a facility to produce 99Mo in a large-scale, cheaper and more efficient way than the methods presently adopted. The innovation that Sorgentina-RF proposes is to create this radionuclide by irradiating stable molybdenum with high energy (14 MeV) neutrons generated from deuterium-tritium fusion reactions, like in future ITER or DEMO reactors. The neutrons are produced on a rotating target irradiated through a D-T plasma, which is created by an ion accelerator. One of the most important tasks of this project is the Tritium Processing System (TPS). It aims to process and recycle deuterium and tritium used in the vacuum chamber for the neutrons production. The TPS receives the gas from the vacuum chamber and separates deuterium and tritium from other impurities generated during the fusion reactions. After that, the system storages the two gases before sending them back to the ion accelerator. It is fundamental to properly manage the fuel to avoid a continuous need of external supply and to reduce its permeation towards the external environment due to its radioactivity. This Master’s Thesis focuses on the design of the TPS: an initial Process Flow Diagram is defined, highlighting the relations between the different subsystems of the TPS. The main components of the system are designed, such as the storage tanks and the tritium piping. For the pipes, a transport model, evaluated considering a steady-state regime, is developed in order to find the most suitable material for its realization, and a CAD for the tubes’ arrangement is proposed. The tritium is initially stored in a uranium getter, and the getter beds are designed in accordance with international standards. All the tritium-facing components, getter included, are contained in gloveboxes specifically designed: the containment barriers must respect international regulations like the ones proposed by the DOE or by ITER. A preliminary design of the gloveboxes is performed determining the most appropriate material to reduce gas permeation and estimating the required minimum thickness. Thereafter, a better design is presented considering the safety features of the gloveboxes required by legislation and the dimensions of the contained components. Finally, the TPS is simulated with Simulink to optimize its operational framework and to represent the logic that regulates the whole system. This model shows the dynamic management of the fuel and how the external sources of tritium and deuterium intervenes. It is a fundamental part in the whole Sorgentina project, being the starting point for the future development of the plant.