Fundamental chemical study on the back end of nuclear fuel cycle, - University, JAERI cooperative research project-

本研究的目的在于建立核燃料循环后端的基础技术。本研究由四个部分组成；(1) TRU循环的核化学研究(2)核燃料和废料的固体化学研究(3)后处理的化学研究(4)废物处置的化学研究。下面描述了每个部分的摘要。(1)建立了锕系元素和镧系元素的核结构、裂变机制和裂变产率的测量方法，获得了一些核数据。对于Tc，实验测定了（n,n'）和（n,p）反应的截面。(2)测定了（U,Np）氧化物的热力学性能和冶金性能，实验确定了贵金属在UO_2中的扩散机理。对废玻璃的力学性能和废陶瓷的耐久性进行了实验研究。(3)实验研究了放线素在水溶液中的形态。采用新型离子交换树脂和溶剂萃取法分离放线素。通过对脉冲柱提取基本因素的细化，提高了后处理计算程序的精度。(4)对放线素在地下水中的溶解行为和放线素在地质环境中的迁移行为进行了实验和理论研究。实验研究了与矿物、胶体和天然有机化合物的相互作用对迁移的影响。

The purpose of this study is to establish fundamental technologies on the back end of nuclear fuel cycle. This study consists of four sections; (1)Nuclear chemical study on TRU cycle (2)Solid state chemical study on nuclear fuel and waste (3)Chemical study on reprocessing (4)Chemical study on waste disposal. The summary for each section is described below.(1)For actinoids and lanthanoids, methods to measure nuclear structure, fission mechanism and fission yield were established, and some nuclear data were obtained. For Tc, cross section of (n,n')and(n,p) reactions were determined experimentally.(2)Thermodynamic properties and metallurgical properties of(U,Np) oxides were measured and diffusion mechanism of noble metals in UO_2 was determined experimentally. Mechanical properties of waste glass and durability of waste ceramics were studied experimentally.(3)Speciation of actinoids in water solution was studied experimentally. New ion-exchange resins and solvent extractions were applied to the separation of actinoids. Precision of calculation code for reprocessing was improved by refinement of basic factors in pulse column extraction.(4)Dissolution behavior of actinoids in groundwater and migration behavior of actinoids in geological environment was studied experimentally and theoretically. The effects of interaction with minerals, colloids and natural organic compounds on the migration was studied experimentally.