Dissolution kinetics of pyrochlore ceramics for the disposition of plutonium
Dissolution kinetics of pyrochlore ceramics for the disposition of plutonium
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用于钚处理的烧绿石陶瓷的溶解动力学
DOI：
10.2138/am.2006.1709
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发表时间：
2006
影响因子：
3.1
通讯作者：
V. L. Legore
中科院分区：
文献类型：
--
作者：
J. Icenhower;D. Strachan;B. Mcgrail;R. Scheele;E. Rodriguez;J. L. Steele;V. L. Legore
摘要在90 °C和pH = 2 ~ 12的条件下，对一组非放射性钛基陶瓷进行了单次β穿透（SPFT）实验。样品含有27.9至35.8重量%的CeO 2作为UO 2和PuO 2的替代物。将组合物配制为TiO 2饱和烧绿石（CeP 1）和富烧绿石基线（CePB 1）陶瓷废物形式。CeP 1和CePB 1陶瓷中的主要物相分别为烧绿石+Hf-金红石和烧绿石+钙钛矿+Hf-金红石。pH = 2至12之间的溶出实验结果表明，pH依赖性较浅，最小值不明确。从实验中确定的在样品表面积（S）和β流动速率（q）范围内的元素释放速率表明，在10.8至10.7 m/s时，溶解速率变得与q/S值无关。溶解速率急剧下降，在较低的q/S值，表明率是受溶解的成分变得集中的溶液饱和效应。CeP 1和CePB 1陶瓷的正向溶解速率分别为1.3（0.30）× 10-3和5.5（1.3）× 10-3 g/m2·d。一旦将速率数据置于溶液饱和状态的背景下，其他实验室获得的溶出速率与本研究的结果相当。这些结果使CeO 2作为UO 2和PuO 2替代物的评价取得进展，并建立了与辐射损伤样品进行比较的基线。
Abstract Single-pass β ow-through (SPFT) experiments were conducted on a set of non-radioactive Ti-based ceramics at 90 °C and pH = 2 to 12. The specimens contained 27.9 to 35.8 wt%CeO2 as a surrogate for UO2 and PuO2. Compositions were formulated as TiO2-saturated pyrochlore (CeP1) and pyrochlorerich baseline (CePB1) ceramic waste forms. Pyrochlore + Hf-rutile and pyrochlore + perovskite + Hf-rutile constituted the major phases in the CeP1 and CePB1 ceramics, respectively. Results from dissolution experiments between pH = 2 to 12 indicate a shallow pH-dependence with an ill-defined minimum. Element release rates determined from experiments over a range of sample surface areas (S) and β ow rates (q) indicate that dissolution rates become independent of q/S values at 10.8 to 10.7 m/s. Dissolution rates dropped sharply at lower values of q/S, indicating rates that are subject to solution saturation effects as dissolved constituents become concentrated. Forward dissolution rates were 1.3(0.30) x 10-3 and 5.5(1.3) x 10-3 g/m2·d for CeP1 and CePB1 ceramics, respectively. Dissolution rates obtained in other laboratories compare well to the findings of this study, once the rate data are placed in the context of solution saturation state. These results make progress toward an evaluation of CeO2 as a surrogate for UO2 and PuO2 as well as establishing a baseline for comparison with radiation- damaged specimens.