Annealing effects of helium implanted single crystals and polycrystalline magnesium aluminate spinel

He migration in implanted UO2 sintered disks

“…The He shift towards the surface suggests that He atoms are mobile at temperatures as low as 600°C and are trapped at implantation induced defects as has already been observed in crystalline Si [10] and also in polycrystalline MgAl 2 O 4 [11]. Corni et al [10] observed a forward He profile shift of 45 nm in 20 keV heliumimplanted silicon (R p ¼ 215 nm) after annealing.…”

“…By correlating ERD, PAS and DC-XRD measurements, the authors ascribed this 14% shift to the interstitial helium movement and trapping in the vacancy-like defects produced by the implantation. A forward shift of the maximum helium concentration was also observed in polycrystalline MgAl 2 O 4 implanted with 900 keV 3 He þ ions [11]. The authors ascribed this shift to helium trapping in pores.…”

Profile measurements of helium implanted in UO2 sintered pellets by using the 3He(d,α)1H nuclear reaction analysis technique

“…The use of the implantation technique to obtain the 3 He standard needs to correct the incident deuteron energy value. At the depth of 130 nm, the 322-1000 keV range corresponds to an energy range between 307 and 992 keV for which the 3 He(d, p) 4 He differential cross-section is measured (Fig. 1).…”

“…Recently, some studies have been devoted to the helium behavior in nuclear materials. Indeed, the principal source of radiation during long term storage of nuclear wastes (glasses or spent fuels) and in matrices for transmutation is a decay of actinides [1][2][3][4][5][6][7]. Amounts of helium could be large, and depending on temperature, this can change the chemical and mechanical stability of the materials.…”

“…For larger depth, its sensitivity is deteriorated by the presence of large sources of background. The main sources of interference with the a signal are pulse pileup from high rates of backscattered deuterons, high energy protons emitted from 3 He(d, p) 4 He and particles emitted from nuclear reactions of other light elements in the target, such as carbon, nitrogen or oxygen.…”