Concept development and candidate technologies selection for the DEMO–FNS fuel cycle systems

Abstract

Within the framework of activities on a pilot industrial hybrid reactor (pilot hybrid plant-PHP) development, the DEMO–FNS fusion neutron source is being designed in Russia. Russian fusion and fission community considers it as the main facility developing prospective nuclear technologies, which should update the results of the ITER researches in the field of physics and control of burning plasma. Progress in the development of the plant and simulations of the fusion fuel cycle allows starting the engineering design of basic fuel cycle systems. In this paper, we consider the new prospective of technological solutions for the tokamak fuel cycle. The possibility of their integration and the analysis of the technology readiness level for them in the Russian Federation are addressed as well. The code simulating the hydrogen isotope flows in a tokamak was significantly upgraded for evaluation of the specific technological solutions as well as for combined modeling of the fuel circulation in the core and divertor plasmas allowing for the pumping, processing, and fuel isotope content control in the plasma. The article describes the core and divertor plasma model used for the calculations and shows the D/T fuel throughput values, which should be provided by the fuel injection systems (NBI and pellets). The dependencies of the HFS and LFS pellet injection frequency necessary for the main plasma supply and ELM control are found for different core and divertor plasma parameters. For the DEMO–FNS core plasma, an operating window has been found in terms of fueling control parameters. It was shown that D and T throughputs of 40–50 Pa·m3 s−1 should be provided by the fuel injection systems (NBI and pellets) to maintain the fusion power up to 40 MW. For the DEMO–FNS core plasma, an operating window defined by the particle confinement times and fuel injection throughputs has been found.

Calculation of Consistent Plasma Parameters for DEMO-FNS Using Ionic Transport Equations and Simulation of the Tritium Fuel Cycle

“…In the described calculations, the parameters of injection of tritium pellets were chosen to provide the given ratio nD+:nT+ = 1:1, i.e., the fraction of tritium in the core plasma is fcore T = 0.5, Injection parameters and source profiles are discussed in detail in Section 3.3. For the fueling of DEMO-FNS, deuterium and tritium pellets are considered, which can be introduced separately or by using the same injection system [21,22]. In the absence of forced isotope content control in the divertor plasma by controlled gas puffing (f div T = f core T ), the fraction of tritium in the plasma is determined mainly by the ratio of the flows S pel T and S pel D .…”

“…However, in the majority of the FC components, there will be a correlation between flows in the FC and the hydrogen isotopes inventory in them. For this reason, during simulations by the FC-FNS code, for each separate set of plasma parameters, flows in FC and fuel component inventories are calculated [22].…”

“…Figure 15a,c show the case with natural ELMs, in which the flows in the FC are lower than in the case of convective ELMs shown in Figure 15b,d. According to the accepted FC architecture [21,22], increasing the particle flows across the plasma increases the loads on the PIS and NBI systems and the hydrogen isotope separation system (ISS) that supply them. At the same time, the flow in the gas injection system (GIS), on the contrary, decreases due to the increase in particle flow in the vacuum vessel due to the partial penetration of pellets through the plasma (the penetration efficiency is <1).…”

“…At the same time, the flow in the gas injection system (GIS), on the contrary, decreases due to the increase in particle flow in the vacuum vessel due to the partial penetration of pellets through the plasma (the penetration efficiency is <1). The maximum flows of particles through the pumping and cleaning systems are independent of the considered scenarios, since they are determined by the engineering parameters: the pressure in the divertor and the pumping rate [22].…”

Isotope engineering achieved by local coordination design in Ti-Pd co-doped ZrCo-based alloys

“…Owing to the design requirements of a fusion reactor for rapid fueling and accurate isotopic composition, major exhaust gases are processed through the TEP and SDS while the remaining gases are allowed to transfer to the ISS for separation of deuterium and tritium. To this end, the SDS equipped with metal hydride getter beds is designed to achieve the rapid storage of unreacted DT gas and the gas delivery with controllable composition 10,11 . Nevertheless, the precise control of fuel D/T ratio is always disturbed by the prominent hydrogen isotope effect that originates from the isotopic affinity difference between gas and solid phases 12 .…”