Retention of D in neutron-irradiated W and desorption were examined after plasma exposure at 773 K. Deuterium was accumulated at a relatively high concentration up to a large depth of 50-100 m due to the trapping effects of defects uniformly induced in the bulk. A
Highlights W samples were pre-irradiated with 4.8 and 20 MeV W ions to various displacements per atom (dpa). Under following exposure to D plasmas radiation-induced defects were occupied by diffusing D atoms. At ≥ 0.1 dpa, the D concentration in the damage zone demonstrated weak dependence on the damage level.
AbstractW samples were irradiated at 300 and 573 K with 4.8 and 20 MeV W ions to displacement damage levels in the range from 0.022 to 50 displacements per atom at the damage peak. 50 m thick W samples were exposed to high flux D plasma at 550 K on the side opposite to the damaged one, whereas 2 mm thick W samples were exposed to low flux D plasma at 403 K on the damaged side. Trapping of deuterium at displacement damage was examined by the D( 3 He, p) 4 He nuclear reaction with 3 He energies between 0.69 and 4.0 MeV allowing determination of the D concentration up to a depth of 6 lm. It was found that (i) at the damage level above 0.1 dpa, the concentration of the W-ion-induced defects responsible for trapping of diffusing D atoms depended very weakly on the numbers of displacements per atom, and (ii) the quasi-saturation concentration of the defects decreased by a factor of two as the W-ion irradiation temperature increased from 300 to 573 K.2
The solubility of zirconium(IV) hydroxide and oxide was measured in the acidic, neutral and alkaline pH at 25 C by an undersaturation method. No influence of the formation of polynuclear and colloidal species on the apparent solubility was observed in the case of the ZrO 2. By using the solubility data of the ZrO 2 and by considering the contributions of the mononuclear species, Zr 4þ , ZrOH 3þ and Zr(OH) 4 (aq), to the solubility curve in the lower pH region, the solubility product was obtained to be log K sp ¼ À62:46 AE 0:10. In the case of the Zr(OH) 4 , no equilibrium was observed during the experimental period up to four months.
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