摘要
79Se是核反应过程中产生的长半衰期(T1/2=2.95×105年)裂片产物核素,具有化学和辐射双重毒性,是高放废物地质处置中重点关注的几个放射性核素之一.硒的溶液化学性质比较特殊,以高价态形式存在的硒酸和亚硒酸,几乎不受溶解度控制,并难以被黏土或花岗岩等处置库围岩介质所吸附,迁移性极强,而当其以低价态(0、–I、–II)形式存在时,易形成固体沉淀.因此将高价态的硒还原生成沉淀是阻滞79Se迁移的最主要方式.从另一方面讲,Fe(II)-矿物是自然界中普遍存在的具有还原性的物质.本文对近年来国内外在Fe(II)-矿物还原亚硒酸方面开展的研究工作进行了一个回顾,并从热力学的角度,对这些矿物还原亚硒酸的可行性及控制产物生成的因素进行了分析.
The radioactive isotope 79Se, with a half-life of 2.95×10^5 years, is presently considered as the key mobile fission product for the disposal of spent fuel and high-level radioactive waste. The solubility of selenium is significantly controlled by its oxidation state, which depends on the redox conditions of the surrounding environment. Tetravalent and hexavalent Se are very soluble and mobile aqueous oxyanions, while Se species with oxidation states 0, -Ⅰ, and -Ⅱ are low solubility solids. Due to the weak adsorption of Se（Ⅳ） and Se（Ⅵ） on natural minerals, in particular on granite or claystone minerals, which are considered as host rocks for nuclear waste disposal, reductive precipitation is considered to be the most effective way to immobilize 795e. On the other hand, Fe（Ⅱ）-bearing minerals （such as pyrite, pyrrhotite, magnetite, etc.） are ubiquitous in geological environment. Due to the reducing capacity, reduction of selenite by Fe（Ⅱ）-containing minerals has received extensive attention worldwide. In this paper, we gave a critical review on the research progress in this field, along with the thermodynamic calculations on the reaction feasibility and the controlling-factor of the reaction products.
出处
《中国科学：化学》
CAS
CSCD
北大核心
2013年第5期536-543,共8页
SCIENTIA SINICA Chimica
基金
核设施退役和放射性废物治理科研专项基金资助(科工计[2007]825
840号)
