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In nuclear fusion reactor facilities, the multi-confinement system and the air detritiation system (ADS) are very important to prevent tritium leaking to the environment. A high-performance tritium...

Cycling stability of ZrCo–H system is extremely important for the long-term operation of the storage and delivery system (SDS) in ITER. Herein, the optimal cycling operation parameters were systematically investigated. It indicates that various parameters, such as hydrogen pressure, temperature, composition, and stoichiometric ratio of H atoms, will all affect the cycling performance of the ZrCo–H system significantly. The decline rate of the hydrogen capacity of the ZrCo–H system is positively correlated with the hydrogen pressure. The experimental result shows that 54% of hydrogen capacity decreases under 28.1 kPa hydrogen pressure, while 30% of attenuation is obtained when the pressure is decreased to 8.1 kPa after 14 cycles. In terms of temperature, the lowest cycling attenuation can be maintained at about 25% after 14 cycles when the dehydrogenation temperature at 550 °C. The effects of doping elements, Hf and Ti, on the cycling stability of ZrCo–H system are also compared. The Zr0.8Ti0.2Co sample exhibits higher cycling capacity than ZrCo and Zr0.8Hf0.2Co samples. The extremely excellent behavior can be achieved when all ZrCo alloys are continuously evacuated during the hydrogen release process, and the attenuation of only 1.1% is observed for Zr0.8Ti0.2Co after 15 cycles. Besides, the cycling attenuation is related to residual stoichiometric ratio of H atoms in ZrCo alloy during the cycling test. When the residual H atoms proportion exceeds 1 in ZrCo during dehydrogenation, hydrogen cycling capacity hardly fades. The XRD results reveal that the disproportionation of ZrCo is directly associated with the cycling degradation, yielding the more stable products of ZrCo2 and ZrH2, However, the disproportionation can be avoided during the cycling process by controlling the stoichiometric ratio of H atoms remained in ZrCo above 1. This study demonstrates that the cycling performance of ZrCo can be substantially improved when the operation parameters are properly adjusted, which provides a significant important reference for durable running of SDS in ITER.

Tritium target is of crucial importance in relation to the development of neutron generator apparatus. However, the prevalent Ti target is now suffering from the intricate procedures for activation, limited tritium content at room temperature (RT) and poor ability to fix the helium. Herein, a succession of new type ZrCo(Ti) alloy targets were designed and fabricated by magnetron sputtering. Firstly, the influence of technological parameters (types of substrate, sputtering temperatures, sputtering time and annealing temperatures) on the assemblage and also the hydrogen storage properties of the ZrCo films were systemically studied. The results show that high sputtering temperature is benefit to acquiring high crystallinity of ZrCo films, but the substrates seem to have no significant effect on that. The thickness and grain size of ZrCo film are both positively related to the sputtering time. However, the hydrogen uptake capacities (0.14 wt%~0.79 wt%) for all the prepared ZrCo films are relatively low. After that, the composition and microstructure of the ZrCo films were further regulated and optimized. On the one hand, Zr1-xTixCo films were constructed by introduction of Ti element, achieving a higher hydrogen absorption capacity (~0.7 wt%), but with weak thermal stability in the subsequent hydrogen desorption process (~80% of hydrogen escaped at 500 °C). On the other hand, the surface of the ZrCo film was modified by a thin layer of Ti, forming a serious of double-layer ZrCo/Ti films. The ZrCo/Ti composite films not only achieve extremely high hydrogen storage capacity (1.85 wt%), but also maintain strong thermal stability (only 15.7% of hydrogen escaped at 500 °C). These findings related to the ZrCo(Ti) films in this paper provide crucial reference for the development of tritiated ZrCo film targets, and spark inspiration even for the design of other new-type tritiated film target.

The thermodynamically and kinetically stable regions of the temperature–H2 pressure phase boundaries for the ZrCo H system were established using the Temperature-Concentration-Isobar (TCI) method. Based on this, the enthalpy change and entropy change values of dehydrogenation and disproportionation reactions were successfully obtained. The average enthalpy change (ΔH) and entropy change (ΔS) estimated from the phase boundaries for dehydrogenation of ZrCoH3 to ZrCo are respectively 103.07 kJ mol−1H2 and 148.85 J mol−1 H2 K−1, which are well agreement with the data reported in literature. The average ΔH and ΔS were estimated to be −120.91 kJ mol−1H2 and -149.32 J mol−1 H2 K−1 for the disproportionation of ZrCoH3, whereas the ΔH and ΔS were calculated to be −84.6 kJ mol−1H2 and -92.29 J mol−1 H2 K−1 for disproportionation of ZrCo. In addition, it was found from the established phase boundaries that the anti-disproportionation property of ZrCo alloy can be enhanced if the phase boundaries of hydrogenation/dehydrogenation are far away from the phase boundaries of disproportionation by adjusting the thermodynamics. Meanwhile, it is possible to keep ZrCo away from disproportionation even at high temperature of 650 °C under hydrogen atmosphere, if the temperature-H2 pressure trajectory is carefully controlled without crossing the phase boundaries of disproportionation. Therefore, the established phase boundaries can be used as a guide to the eye avoiding disproportionation and improving the anti-disproportionation property of ZrCo alloy.

Tritium must be strictly defended in tritium systems because of its permeability and radioactivity. Detritiation devices are required in tritium systems, such as the glove box detritiation system, ...

Strong Metal-Support Interactions (SMSI) are important in Pt supported catalysts for their catalytic performance. SMSI in Pt/CeO 2 , Pt/Ce 0.7 Zr 0.3 O 2 and single atom S-Pt/Ce 0.7 Zr 0.3 O 2 catalysts were studied by in situ Raman spectroscopy and H 2 Temperature-Programmed Reduction. Evidence of SMSI in Pt/CeO 2 and Pt/Ce 0.7 Zr 0.3 O 2 that improve the reduction properties of supports other than H 2 dissociation and spillover is obtained. It was also found that Pt-O and Pt-O-Ce bonding in the said catalysts play an important role in SMSI. The Pt bonding could be ascribed to Pt oxides species (Pt 1 + and Pt 2 + ) with different Pt adsorption sites on CeO 2 surface and which act as intermediates in reduction process. This gives a new insight into the SMSI and explains the observed Pt/CeO 2 reduction characteristics.

Tritium is indispensable to the fusion reactor engineering, and it must be seriously defended because of its radioactivity and permeability. The method of catalytic oxidation and absorption is the most widely used process for tritium cleanup so far, in which detritiation catalyst is of great importance. The poor stability caused by the agglomeration of noble metal limits the life of detritiation catalysts. Here, Anti–Ostwald Ripening is used to prepare single-atom detritiation catalysts S-Pt/Ce0.7Zr0.3O2 for tritium (HT, DT and T2) oxidation. Single-atom dispersed Pt ensures the catalytic activity and decreased the economic cost. The strong metal-support interaction (SMSI) keeps Pt from aggregating, thus increases the working life of catalyst. And Pd based catalyst supported by a cation ordered κ-Ce2Zr2O8 is prepared for tritiated methane (CH4-xTx) oxidation. Tritiated methane is mostly oxidized by Pd/κ-Ce2Zr2O8 at about 450 °C, which is at least 50 °C lower than normal catalysts (such as Pd/Al2O3).