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The fusion neutron source is an advanced facility for scientific research, testing structural materials of future fusion reactors, nuclear waste utilization, fissile fuel production and control of sub-critical nuclear systems. Tokamak is one of the most promising systems to build fusion neutron sources with a fusion power over 10 MW. Plasma maintenance requires the injection of fuel mixture containing hydrogen isotopes (deuterium and tritium) into the vacuum chamber with subsequent fuel pumping and processing. To simulate hydrogen isotope flows in the fusion neutron source fuel system, the FC-FNS model of the fuel cycle has been developed. This paper describes the modification of FC-FNS model and includes the results of calculations of tritium inventories in the DEMO-FNS fusion neutron source with different T/D ratios in plasma. Fuel pellet injection (separately injection of D 2 , T 2 and DT) from the HFS and LFS is the main method of fueling. Frequency of D/T pellet injection providing the stable plasma operation for different NBI gas supply scenarios was chosen. Tritium inventory in the fuel cycle depending on the scenario and D:T ratio in plasma was calculated. Use of the D + T beam is reasonable only when T fraction in plasma equals 0.5, while the D – beam is more effective with higher fraction values within the range of 0,6–0,7. [ABSTRACT FROM AUTHOR]

Abstract The conceptual design of the fuel cycle systems of a hybrid fusion neutron source DEMO-FNS is conducted in this paper. Fusion neutron source is promising for research, testing of structural materials of future fusion and fusion-fission hybrid reactors, utilization of nuclear waste, fuel breeding and control of subcritical nuclear systems. The facility operation requires the continuous injection of the fuel mixture of hydrogen isotopes (deuterium and tritium) into the vacuum chamber, as well as its subsequent pumping and processing. The key task of the fuel cycle (FC) design is to create a closed system providing the conditions for fusion burning in plasma, with reduce tritium inventory in the system elements. For this purpose "FC-FNS" electronic model has been actively developing as a tool for estimating fluxes of DT fuel and T inventories in systems where tritium is used. The paper describe the conceptual fuel cycle design for the DEMO-FNS facility and results of the modeling of hydrogen isotopes flows and inventories in fuel systems for steady-state operation mode. The paper compares various conceptual approaches to neutral beam injection system gas supply and chooses the optimal variant for its integration into the DEMO-FNS FC. [ABSTRACT FROM AUTHOR]

To investigate systematically the effects of Re and other elements on deuterium (D) retention, W and binary W-alloys (Re, Mo and Ta) were irradiated with 6.4 MeV Fe ions at high temperatures (1073–1273 K) and then exposed to D 2 gas at 673 K. Depth profiles of D were measured by nuclear reaction analysis (NRA), and D retention was determined by thermal desorption spectrometry (TDS) and NRA. The addition of 5 at.% Re into W reduced the content of D trapped at radiation-induced defects created by irradiation with the Fe ions at 1273 K to the peak damage level of 5 displacements per atom (dpa). At Re fractions of 1, 3 and 5 at.%, comparable effects on D retention were observed after irradiation to 0.5 dpa at 1073 K. The addition of Mo and Ta to W resulted in no visible effects in D retention. [ABSTRACT FROM AUTHOR]