Pacific Northwest National Laboratory, Richland, Washington 99352, USA.
Environ Sci Technol. 2012 Nov 20;46(22):12616-22. doi: 10.1021/es302734y. Epub 2012 Oct 26.
The immobilization of technetium-99 ((99)Tc) in a suitable host matrix has proven to be a challenging task for researchers in the nuclear waste community around the world. In this context, the present work reports on the solubility and retention of rhenium, a nonradioactive surrogate for (99)Tc, in a sodium borosilicate glass. Glasses containing target Re concentrations from 0 to 10,000 ppm [by mass, added as KReO(4) (Re(7+))] were synthesized in vacuum-sealed quartz ampules to minimize the loss of Re from volatilization during melting at 1000 °C. The rhenium was found as Re(7+) in all of the glasses as observed by X-ray absorption near-edge structure. The solubility of Re in borosilicate glasses was determined to be ~3000 ppm (by mass) using inductively coupled plasma optical emission spectroscopy. At higher rhenium concentrations, additional rhenium was retained in the glasses as crystalline inclusions of alkali perrhenates detected with X-ray diffraction. Since (99)Tc concentrations in a glass waste form are predicted to be <10 ppm (by mass), these Re results implied that the solubility should not be a limiting factor in processing radioactive wastes, assuming Tc as Tc(7+) and similarities between Re(7+) and Tc(7+) behavior in this glass system.
将锝-99((99)Tc)固定在合适的基质中已被证明是全世界核废料研究人员面临的一项挑战。在这种情况下，本工作报道了铼在硼硅酸钠玻璃中的溶解度和保留情况，铼是(99)Tc 的非放射性替代物。在真空中密封的石英安瓿中合成了目标 Re 浓度为 0 至 10000ppm[质量，添加为 KReO(4)(Re(7+))]的玻璃，以最大限度地减少在 1000°C 熔融过程中因挥发而导致的 Re 损失。通过 X 射线吸收近边结构观察到，所有玻璃中均以 Re(7+)形式存在铼。使用电感耦合等离子体发射光谱法确定了 Re 在硼硅玻璃中的溶解度约为 3000ppm（质量）。在更高的铼浓度下，作为碱高铼酸盐的晶体夹杂物保留在玻璃中，通过 X 射线衍射检测到。由于玻璃废物形式中的(99)Tc 浓度预计<10ppm（质量），这些 Re 结果表明，假设 Tc 为 Tc(7+)，并且 Re(7+)和 Tc(7+)在该玻璃系统中的行为相似，在处理放射性废物时，溶解度不应成为限制因素。
