中文摘要：

黄铁矿是地质介质中普遍且稳定存在的矿物,由于S22-的还原性强于Fe2＋,可望作为强还原剂将高价核素还原为低价态,但黄铁矿的有氧氧化会产生酸,这对放射性核素的迁移阻滞不利。本工作使用PHREEQC软件,以中国甘肃北山五一井地下水为实例,模拟了黄铁矿还原U、Se、Tc等的反应路径。结果表明,在无氧的地下处置库氛围中,黄铁矿的存在能有效地还原高价态的U、Se、Tc,将其浓度降低至极低水平而阻滞其迁移,且反应后的溶液pH值有升高趋势。

英文摘要：

The mobility of redox sensitive nuclides is largely dependent on their valence state.The radionuclides that make the dominant contributions to final dose calculations are redox sensitive.Almost all the radionuclides（except 129I） have higher mobility at high valence state,and correspond to immobilization at low valence state due to the much lower solubility.Pyrite is an ubiquitous and stable mineral in geological environment,and would be used as a low-cost long time reductant for the immobilization of radionuclides.However,pyrite oxidation is supposed to generate acid,which will enhance the mobility of nuclides.In this paper,the reaction path between U,Se,Tc and pyrite in the groundwater from Wuyi well in Beishan area of China has been simulated using geochemical modeling software.According to the results,pyrite can reduce high valent nuclides to a dinky-level effectively,with the pH slightly increasing under anaerobic condition that is common in deep nuclear waste repositories.