Simulation of Fuel Flows in Injection Systems of Demo-FNS Hybrid Facility Involving Coupled Modeling of the Core and Divertor Plasmas

Abstract

The FC-FNS fuel cycle model is used to calculate the hydrogen isotope flows in the fuel systems of a tokamak-based fusion neutron source (DEMO-FNS) with parameters R/a = 3.2 m/(L m), B = 5 T, I_p = 4–5 МА, P_NBI = 30 MW, P_ECR = 6 MW, and DT fusion power P_fus = 40 MW. The FC-FNS (Fuel Cycle for Fusion Neutron Source) model has been significantly upgraded. For the first time, a joint simulation of gas, solid-state, and plasma flows of fuel mixtures in the regions of core and divertor plasma with the injection of neon impurity into the divertors was carried out. The possibility of reducing the fuel flows in the pumping and injection systems with the use of Ne impurity in the divertor has been substantiated. For the previously accepted scenarios of the D⁰ + T⁰ and D⁰ heating beam, the tritium inventories in the fuel systems were calculated taking into account the T breeding and burnup at a different T/D (f_T) ratio in the core plasma. It was shown that, for the D + T beam, it is advisable use f_T = 0.5, and for the D beam, it is more expedient to use f_T = 0.6–0.7. The fuel injection was fundamentally revised. The main fueling method is injection of fuel pellets, which is now represented by separate D₂, T₂, and DT injectors and carried out from HFS and LFS. The DEMO-FNS injection system operating modes were analyzed as a function of the core parameters, and the gas flows were evaluated for various D₂/T₂/DT pellet-injector modes. The results obtained have allowed us to choose the fuel system configuration with the minimum tritium inventory (<2 kg) and the lowest reprocessing time.