Irradiation effect on deuterium behaviour in low-dose HFIR neutron-irradiated tungsten

Abstract

Tungsten samples were irradiated by neutrons in the High Flux Isotope Reactor (HFIR), Oak Ridge National Laboratory at reactor coolant temperatures of 50-70 • C to low displacement damage of 0.025 and 0.3 dpa. After cooling down, the HFIR neutronirradiated tungsten samples were exposed to deuterium plasmas in the Tritium Plasma Experiment, Idaho National Laboratory at 100, 200 and 500 • C twice at the ion fluence of 5 × 10 25 m −2 to reach the total ion fluence of 1 × 10 26 m −2 in order to investigate the near-surface deuterium retention and saturation via nuclear reaction analysis. Final thermal desorption spectroscopy was performed to elucidate the irradiation effect on total deuterium retention. Nuclear reaction analysis results showed that the maximum near-surface (<5 µm depth) deuterium concentration increased from 0.5 at% D/W in 0.025 dpa samples to 0.8 at% D/W in 0.3 dpa samples. The large discrepancy between the total retention via thermal desorption spectroscopy and the nearsurface retention via nuclear reaction analysis indicated the deuterium was trapped in bulk (at least 50 µm depth for 0.025 dpa and 35 µm depth for 0.3 dpa) at 500 • C cases even in the relatively low ion fluence of 10 26 m −2 .

Deuterium retention and thermal conductivity in ion-beam displacement-damaged tungsten

“…Undamaged PISCES--B data points derived from published results [36]. Neutron data from Shimada et al [28].…”

“…Shimada and collaborators carried out plasma-implanted D retention studies in neutrondamaged W [25][26][27][28][29][30]. NRA was used to find the near-surface retained D and was compared to TDS.…”

Microstructural modifications in tungsten induced by high flux plasma exposure: TEM examination

“…In addition, a computational assessment of D retention by TMAP when compared with experimental TDS spectra also suggests the existence of retention deeper than 10 μm (see e.g. [8]). However, the bulk retention in the high flux exposure (flux>10 22 ion m −2 s −1 ) up to 600 K represents a minor part of the integral retention, while most of D is trapped within first several μm.…”

Defect annealing and thermal desorption of deuterium in low dose HFIR neutron-irradiated tungsten

“…Details of the TMAP simulation and mass transport property used in tungsten are described elsewhere [9,13]. In this study the enhanced diffusion zone (EDZ) model that Venhaus and Causey simulated tritium plasma implantation was used to simulate both plasma exposure phase and thermal desorption phase in order to accurately elucidate deuterium behavior in neutron-irradiated tungsten [14][15][16][17]. Experimental sample transfer procedure in air from the TPE vacuum chamber to the TDS vacuum chamber was not simulated, and the sample were assumed to be in vacuum at room temperature for 19 h from the end of plasma exposure to the beginning of TDS instead.…”