Hydrogen accumulation in nanostructured as compared to the coarse-grained tungsten

Object kinetic Monte Carlo simulations of irradiated tungsten for nuclear fusion reactors

“…In both MW and NW, the top surfaces were considered as desorption surfaces, whereas atoms reaching the bottom surfaces were considered to move further deep into the bulk and thus ignored. The temperature in all the simulations was 300 K, as the experiments were carried out at this temperature [49]. In order to mimic the experimental procedure as much as possible, an annealing of 10 days at 300 K was also simulated after C and/or H irradiation during 5 h, in every simulated case (both MW and NW in the three different irradiation scenarios).…”

“…Hence, nanostructured W is expected to have a better response to ion irradiation. However, this behaviour is not yet clear, apart from experimentally demonstrated fact that a high GB density has a direct influence on retention of light species in W [49].…”

“…Johnson et al [131], Heinola et al [132], Ohsawa et al [133], Liu et al [130] and Fernandez et al [122] The region between 0 and 150 nm (in blue) has been taken into account neither in the results nor in the discussion because it is highly influenced by surface contamination [49] is divided into small boxes, called "mesh elements". The "mesh element"…”

“…[44] it has been reported that grain boundaries act as defect sink for vacancies, SIAs and He atoms, thereby presenting nanostructured W with high grain boundary density is a candidate as material to prove whether it presents superior radiation tolerance than monocrystalline W. At grain boundaries, vacancies and SIAs annihilate [45]. Nanocolumnar W has recently been fabricated with a high grain boundary density [43] and it has been experimentally observed that high grain boundary density has a direct influence in the retention of light species [49].…”

“…[122,123,128,[130][131][132][133], show a binding energy of a H atom to a vacancy higher than 1 eV (see Figure 3.5). Nanostructured materials have a large density of grain boundaries (GBs) which, depending on the irradiation conditions, have a clear influence on the distribution of both FPs and light species such as H [49]. Refs.…”