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ZrCo alloy has been considered as a tritium storage material to replace uranium for large-scale hydrogen isotope storage and delivery in tritium plant of the magnetic confinement nuclear fusion reactor. However, the disproportionation of ZrCo greatly obstructed its aspects to engineering application. A multifaceted understanding about the intrinsic nature of disproportionation reaction, and proposing anti-disproportionation strategies from material design have always been the bottleneck and hotspot in the tritium science and technology field. Herein, we studied the anti-disproportionation properties of Zr(Ti)Co alloy with thin film structure, and the effects of film thickness and Ti substitutions on the anti-disproportionation properties of the films were obtained. Firstly, a series of ZrCo films with different deposited time were prepared by magnetron sputtering instrument. The disproportionation ratio of the 2 h deposited ZrCo film (1.641μm) is 23.9%, and attenuated with the increase of film thickness. It indicates that the anti-disproportionation properties of the film structure is significantly better than that of ZrCo particle (68%). The microtopography analysis shows that the micro stress in the film structure is beneficial to hinder the disproportionation process. However, the hydrogenation reaction is also obviously inhibited in the ZrCo film. In addition, Ti doping can further improve its anti-disproportionation performance (10.3–7.3% for the 2 h deposited Zr 1-x Ti x Co film) without significantly reducing the hydrogen absorption capacities of the ZrCo flims. The anti-disproportionation performance is closely related to the weakened interaction between Zr and H atoms, after Ti doping into the ZrCo flim, leading to the impaired driving force for disproportionation reaction. The study in this work can provide an important reference for the anti-disproportionation modification of ZrCo alloys. • Hydrogen storage performance of ZrCo with film structure were investigated. • Anti-disproportionation behavior of ZrCo film is related to thickness. • Anti-disproportionation properties of ZrCo film is better than that of particles. • The Ti doping improve the anti-disproportionation performance of ZrCo films. • The Ti enhancement mechanism was obtained from the perspective of binding energy. [ABSTRACT FROM AUTHOR]

Fast heat and mass delivery with high cycling stability of the core component, hydrogen storage bed, in SDS are essential for the operation of the future tritium factory in ITER project. However, the aforementioned properties are still perplexing in large-capacity ZrCo bed, especially for that with secondary containment structure required by the actual tritium operation in the future. Herein, the performance including heating, cycling and cooling with two different size ZrCo beds (loading of ZrCo are 200 g and 2000 g respectively) were systematically studied. The experimental data shows that the maximum heating ability of the middle-size/full-scale storage bed are both about 10 °C/min, and the maximum hydrogen absorption capacity of these ZrCo beds are 44.6 L/405.5 L, respectively. Besides, hydrogen pressure and hydrogen retention during the following desorption can affect the cycling performance of the ZrCo bed. The use of transfer pump can reduce the pressure of the bed during the hydrogen desorption process (operated at 500 °C), which inhibits the disproportionation reaction of the ZrCo alloy. However, the degree of hydrogen pressure reduction in two the types of ZrCo bed are different. As a result, the cycling capacity of the middle-size bed (93.4%, lower hydrogen pressure) is higher than the full-scale bed (68.7%, higher hydrogen pressure) after 10 cycles. When the transfer pump was not used and operated at lower temperature (350 °C), the beds cannot release hydrogen completely, and partial hydrogen atoms are retained in the ZrCo alloy. The middle-size bed still maintains a hydrogen storage capacity of 94.5% after 10 cycles, while 75.9% of the hydrogen storage capacity remained for the full-scale bed. Therefore, the increase of hydrogen surplus in ZrCo alloy is helpful to improve its cycling stability. At last, the cooling performances of the beds under 10 different cooling methods were studied. Among the cooling methods, the best cooling rate was achieved by filling nitrogen in the secondary containment cavity and flowing water passing through the cooling circuit of the bed. This work will provide a crucial reference for the design and optimization of the subsequent operation technology of SDS in ITER. • Thin double-layered annulus ZrCo bed with secondary containment cavity is manufactured. • Real-time pumping transfer helps to improve the circulation stability of the ZrCo bed. • Keep remaining H in the ZrCo is benefits to improve its cycling stability. [ABSTRACT FROM AUTHOR]