Study On The Removal Technology Of Deuterium In Tungsten By Thermal Desorption And Hydrogen Isotope Exchange

China will build a tritium self-sustaining fusion engineering experimental reactor?CFETR?with power generation output function around 2030.As the most promising plasma oriented material in CFETR device,the reasonable evaluation of hydrogen isotope residence in tungsten and the effective removal of hydrogen isotope residence are important issues to be considered in the safe design and stable operation of the device.Deuterium was introduced into tungsten materials by gas-phase thermal charging method,the influence of grain size and doped elements on deuterium residence in tungsten was systematically investigated,and the removal efficiency of deuterium residence in tungsten by thermal desorption method and hydrogen isotope exchange method was studied and evaluated.Firstly,the thermal desorption data of D₂ in gas phase of pure tungsten and tungsten alloys with different surface topologies were compared under the same experimental conditions.Among several pure tungsten samples,deuterium retention was the lowest?0.39appm?in the pure tungsten samples prepared by hot rolling process provided by institute of solid state physics,Chinese academy of sciences;The D desorption amount of tungsten doped with different elements is quite different,and the retention amount?0.64appm?of0.5%wt ZrC doped tungsten sample under the same conditions is one order of magnitude lower than that of V-Ta-Ti-Cr doped tungsten sample?1.74appm?and Y₂O₃ doped tungsten sample?10.06appm?;Compared with V-Ta-Ti-Cr and Y₂O₃ tungsten,ZrC particles are small and mainly distributed in the grain boundary of the matrix material,which to some extent reduces the deuterium retention in the grain boundary.In contrast,doping ZrC is beneficial to reduce the retention of D in W.Secondly,the surface morphology changes of w-0.5wt%ZrC samples with different crystal sizes?3⁹0?m?were studied after annealing,gas phase thermal charging and thermal desorption.Quantitative thermal desorption spectra showed that deuterium desorption decreased with grain size increasing.In the incomplete recrystallization state,the desorption was the lowest,reaching 0.47appm.Therefore,compared with the above materials,w-0.5wt%ZrC is more suitable to be used as plasma-oriented materials in practical fusion reactors.Then,the removal effect of deuterium resident in tungsten by thermal analysis was studied.Deuterium mainly exists in tungsten as a solid solution atom;The thermal desorption activation energies of D₂ and HD in w-aetna samples were 2.18eV and 2.17eV respectively;2h under 673K in the process of vacuum insulation except the deuterium no obvious deuterium release,but prolonged annealing to 3h,can make the temperature rising subsequent thermal stripping deuterium spectrum peak is shifted to the low temperature;Experience above 773K,2h vacuum insulation except the deuterium samples,deuterium removal rate reached more than 80%,in addition to the obvious effects of deuterium.Finally,the removal of deuterium in pure tungsten by hydrogen isotope exchange method is studied.Found 373-673K temperature range,100kPa pressure of hydrogen isotope exchange,the deuterium in tungsten no obvious removal effect,but with the extension of hydrogen isotope exchange of temperature,time,deuterium hot stripping peak shift to low temperatures.Hydrogen isotope exchange can be made deep trap of deuterium atom can low to capture the position of the migration,773-973K within the scope of the hydrogen isotope exchange effect is obvious,deuterium removal rate reached more than 65%.