Alpha-Decay Damage of Cm-Doped Perovskite

Abstract

AbstractCurium-doped perovskite slurry, which had the nominal composition of Ca0.98919(Cm, Pu)0.0108l Al0.0108l Ti0.98919O3, was calcined at 750°C for 2 h and then hot-pressed at 1250°C and 29MPa for 2 h. The hot-pressed cylinder samples had the specific 244Cm activity of 22.3 GBq·g−l on 31 March 1993. Their average density was 4.083 g·cm−3 after the samples got a cumulative dose of 0.7}1017 α decays·g−l. Change in density of Cm-doped perovskite reached 0.8% at a dose of 5}1017 α decays·g−l. The rate of density change was slightly larger in the present perovskite material than in Cm-doped Synroc reported previously. Half-disk perovskite specimens, which had accumulated doses of 1.6}1017 and 4.0}1017 α decays·g−l, were MCC-1 leach tested in pH˜2 solution at 90°C for two months. The leach rates of these specimens derived from weight losses were 1.7 and 2.3 g·m−2·day−l, respectively. These high leach rates caused a significant increase in pH in the later stage of the leaching runs. As-leached surfaces of Cm-doped perovskite showed the formation of anatase (TiO2). For the first 28 days, the Ca and Cm leach rates at the two different doses increased with leach time. More damaged specimens tended to give higher leach rates. In the final 28-day leaching run, both leach rates at the two different doses converged on each lower values although the Cm leach rate was lower than the Ca leach rate by a factor of >20. Nonradioactive perovskite material showed similar changes in Ca leach rate and pH to the Cm-doped one although the as-leached surfaces of the former material showed much higher degree of alteration of perovskite to anatase.