SOM电解法对氟盐冷却剂进行在线净化的研究  

On-line purification of fluoride salts coolant by an SOM electrolysis method

作　　者：左勇[1,2] 申淼 谢雷东 谢宏伟[3] 翟玉春 ZUO Yong;SHEN Miao;XIE Leidong;XIE Hongwei;ZHAI Yuchun(Shanghai Institute of Applied Physics,Chinese Academy of Sciences,Shanghai 201800,China;Dalian National Laboratory for Clean Energy,Chinese Academy of Sciences,Dalian 116023,China;Northeastern University,Shenyang 110819,China)

机构地区：[1]中国科学院上海应用物理研究所,上海201800 [2]中国科学院洁净能源创新院,大连116023 [3]东北大学,沈阳110819

出　　处：《核技术》2020年第11期20-29,共10页Nuclear Techniques

基　　金：中国科学院洁净能源先导专项(No.XDA21000000)资助。

摘　　要：熔盐堆氟盐冷却剂在服役周期内应保持较高的纯度以维持其对堆结构材料良好的相容性。氟盐中的O^2−以及Cr^3+、Fe^2+、Ni^2+等过渡金属离子可能增强熔盐腐蚀性,并导致液态核燃料形成难溶氧化物进而影响堆的安全性。通过在线净化的方式去除这些有害杂质可提高氟盐冷却剂的服役周期和增强反应堆的安全性。基于固体氧化物膜(Solid Oxide Membrane,SOM)电解法的在线净化方法可有效去除上述有害杂质,从热力学和动力学的角度分析了各种影响SOM电解脱氧净化的因素。600℃下的SOM电解脱氧试验结果表明:通过SOM(Zn)阳极和石墨阴极电解,可将氟盐中的O^2−降低至100μg·g^−1以下,将Cr^3+、Fe^2+、Ni^2+等过渡金属离子降低至10μg·g^−1以下,显示了SOM电解法在氟盐冷却剂在线净化方面具有很好的应用前景。[Background]As a coolant for molten salt reactors(MSRs),fluoride salt should be kept clean during the whole service life.Impurities in the salt(such as O2−and Cr3+,Fe2+,Ni2+,et al.)could greatly prompt the corrosive behaviour.Otherwise,O2−may react with uranium ions(U4+)to form UO2 precipitation in the fuel salts,which may cause unpredictable security problem for the MSRs.[Purpose]This study aims to propose an on-line purification concept of fluoride salts to improve the quality of the fluoride salts coolant for security assurance.[Methods]Based on a solid oxide membrane(SOM)electrolysis method,the SOM anode was made from an 8-YSZ(8 mol%Y2O3-92 mol%ZrO2)tube containing metal deoxidizers while the graphite rod or container acted as the cathode.The effects of different metal deoxidizers and electrolysis conditions using SOM electrodes on the purification of FLiNaK salt under the temperature of 600℃ were investigated by experiments.When DC current was applied to the two electrodes,impurities in the fluoride salts(such as O^2−,Cr^3+,Fe^2+,Ni^2+,H2O)was collected or decomposed on either anode or cathode.The factors affecting the deoxidation and purification of SOM electrolysis were analyzed from the point of thermodynamics and kinetics.[Results]Experimental results show that O^2− and transition metal ions(Cr^3+,Fe^2+,Ni^2+)are decreased to below 100μg·g^−1 and 10μg·g^−1 respectively after 40 h-electrolysis with an SOM(Zn)anode and a graphite cathode in fluoride salts at 600℃.Impact factors on the deoxidization behavior of the SOM process were discussed from the perspective of thermodynamic and kinetics.[Conclusions]It is indicated that the SOM electrolysis method has a good application in the on-line purification of fluoride salts coolant of the MSRs.

关 键 词：熔盐堆 氟盐 在线净化 固体氧化物膜 钇稳定氧化锆 

分 类 号：TL99[核科学技术—核技术及应用]