膨润土的膨胀性衰减研究

利用地球化学软件Phreeqc模拟了高放核废料处置库的高压实MX80膨润土中发生的水文地球化学反应，基于长时间尺度的研究的需要，忽略热、力、流等因素的影响，主要考虑了K⁺、Ca²⁺、Na⁺、Mg²⁺四种阳离子的离子交换和矿物溶解沉淀反应，建立了膨润土中的一维离子运移反应模型。模拟了不同外界流体作用下，膨润土化学组分在时间和空间上的变化。结合化学组分变化结果，对膨润土膨胀性衰减情况进行了计算和评估。得到1万年后海水和地下水环境下的MX80膨润土膨胀性衰减系数分别达到0.79和0.91。

Research of the Swelling Capacity Decay of Bentonite

The hydrogeochemical reaction of the high-pressure MX80 bentonite in the high-level nuclear waste repository was simulated by the geochemical software Phreeqc. Based on the research need in a long time, the influences of heat, force and flow are ignored. A one-dimensional transport model was established mainly in consideration of the cation exchange of K⁺, Ca²⁺, Na⁺, Mg²⁺, mineral dissolution and precipitation reactions. The chemical components change of the bentonite in time and space was simulated under the action of different outside fluid.The swelling capacity decay of the bentonite was evaluated. Decay coefficient of the MX80 bentonite reached 0.91 in the underground water and 0.79 in the seawater after 10000 years.