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Chemical Activities of Components in Simulated High-Level Radioactive Waste Glasses and Their Vaporization Behavior

模拟高放射性废玻璃中组分的化学活性及其汽化行为

基本信息

批准号：
63580176
负责人：
ASANO Mitsuru
金额：
$ 1.15万
依托单位：
KYOTO UNIVERSITY
依托单位国家：
日本
项目类别：
Grant-in-Aid for General Scientific Research (C)
财政年份：
1988
资助国家：
日本
起止时间：
1988 至 1989
项目状态：
已结题

项目摘要

High-level radioactive wastes are solidified by incorporating into borosilicate glasses. To establish the safety in the vitrification processes, it is very important to suppress the vaporization of fission products from the glasses. In this research project, vapor species and their partial pressures over various borosilicate glasses with simulated high-level radioactive wastes were studied. From these data, the degree of the suppression of the vaporization for alkalis, tellurium and strontium was studied quantitatively by comparing the chemical activities of the corresponding components in the glasses.1. The oxide component of R_2O-B_2O_3-SiO_2(R = Li, Na, K, Rb and Cs) for borosilicate glasses is rewritten to be RBO_2-SiO_2 by the use of the pseudo component. In these glasses, the chemical activity of CsBO_2 component is the smallest among RBO_2 ones. This indicates that the vaporization of Cs is most suppressed thermochemically among alkalis.2. The vaporization of alkali borosilicate glasses in the R_2O-Cs_2O-B_2O_3-SiO_2 system, where R = Li, Na, K and Rb, was studied. Partial pressures of CsBO_2(g) over the glasses with Li and Na are lower than those with K and Rb, indicating that chemical activities of the CsBO_2 components in the glasses with Li and Na are small.3. Chemical activity of TeO_2 component in the alkali borosilicate glass is extremely small in comparison with that for the CsBO_2 one, that is, the vaporization of TeO_2(g) is suppressed much more than that of CsBO_2(g).4. From the glass with the oxide composition of SrO・B_2O_3・SiO_2, strontium vaporizes as Sr(g), SrBO_2(g) and SrsiO(g).5. The chemical activity of Sr(BO_2)2 component in the borosilicate glass is smaller than that of RbBO_2 one. From this comparison, the suppression of the vaporization of Sr is more difficult thermochemically than that of Rb.

高放射性废物通过掺入硼硅酸盐玻璃而固化。为了保证玻璃化过程的安全性，抑制玻璃中裂变产物的汽化是非常重要的。在本研究项目中，研究了模拟高放射性废物的各种硼硅酸盐玻璃上的蒸汽种类及其分压。根据这些数据，通过比较玻璃中相应组分的化学活性，定量地研究了碱、碲和锶的汽化抑制程度。利用伪组分将硼硅酸盐玻璃中的氧化组分rbo_2 - b_2o_3 - sio_2 （R = Li, Na， K， Rb和Cs）改写为RBO_2-SiO_2。在这些玻璃中，CsBO_2组分的化学活性是RBO_2组分中最小的。这表明Cs的汽化在碱中受到最大的热化学抑制。研究了碱硼硅酸盐玻璃在R = Li、Na、K、Rb的r22o - cs22o - b_2o_3 - sio_2体系中的汽化过程。含有Li和Na的玻璃表面的CsBO_2分压(g)低于含有K和Rb的玻璃表面的分压(g)，说明含有Li和Na的玻璃表面CsBO_2组分的化学活性较小。4.碱硼硅酸盐玻璃中TeO_2组分的化学活性与CsBO_2组分相比非常小，即TeO_2(g)的汽化受到的抑制远大于CsBO_2(g)。在SrO·B_2O_3·SiO_2氧化物组成的玻璃中，锶蒸发为Sr(g)、SrBO_2(g)和SrsiO(g)。硼硅酸盐玻璃中Sr(BO_2)2组分的化学活性小于RbBO_2组分。从这个比较可以看出，抑制Sr的汽化比抑制Rb的汽化更困难。