Irradiation Temperature Determination by Electrical Resistivity Measurements

Hardness and electrical resistivity of molybdenum in the post-irradiated and annealed conditions

“…General trends in previously reported irradiated electrical resistivity data [12][13][14] after high dose exposure (100-610 · 10 24 n/m 2 , E > 0.1 MeV) are consistent with the results reported here: (1) the largest increase in electrical resistivity was observed at lower irradiation temperatures, and (2) small increases in electrical resistivity were observed at higher irradiation temperatures. However, decreases in electrical resistivity have been reported at relatively high irradiation temperatures (910°C and 1050°C).…”

“…However, decreases in electrical resistivity have been reported at relatively high irradiation temperatures (910°C and 1050°C). The larger changes in resistivity at all irradiation temperatures for previous studies [12,13] likely result from the higher neutron fluence and lower materials purity in comparison to this work. Irradiation to higher neutron fluences than used in this work would result in the accumulation of transmutation products and irradiation defects that could result in different trends than reported herein.…”

“…A slightly higher temperature for full recovery was identified for the higher neutron fluence 605°C irradiation, which may indicate that saturation of the defect density has been achieved under these conditions [5]. Irradiation of molybdenum at 605°C would be expected to result in no dislocation loops and a coarser distribution of voids than observed for the 270°C irradiations, and coarsening of these larger voids would therefore be expected to occur at higher annealing temperatures of 800-1100°C [12,13,22,26,30].…”

“…Irradiation of molybdenum to high neutron fluences results in the formation of a void lattice, and the spacing of voids is much finer at lower irradiation temperatures with finer void sizes observed at lower irradiation temperatures [39,40]. Although a void lattice has not been observed at irradiation temperatures 6420°C, the formation of finely spaced, small voids and/or dislocation loops has been reported [12,13,22,26,32,39]. Irradiation of molybdenum at 270°C would be expected to result in the formation of finely spaced dislocation loops and voids that are small in size, which would be expected to recover at lower isochronal annealing temperatures as the diffusion distance between the loops and voids is shorter.…”

“…Electrical resistivity measurements may also be used as an indirect measure of defect density, where larger increases in electrical resistivity are observed following irradiation at lower temperatures due to the presence of a higher number density of defects [12][13][14]. The purpose of this work is to determine the change in hardness and electrical resistivity of wrought LCAC molybdenum sheet following irradiation and post-irradiation annealing and to use this data as an indirect measure of defect density for determining the kinetics of recovery and defect annihilation following irradiation between 270°C and 1100°C.…”