中国高放废物深地质处置的缓冲材料选择及其基本性能

人类的许多生产、生活活动均可能产生不同活度的放射性废物,其中高放废物的安全处置倍受全球科学家和广大公众所重视。目前深地质处置被国际上公认为处置高放废物的最有效可行的方法。借鉴国外成熟的技术和经验,我国采用多重工程屏障系统(包括废物固化体、废物容器及其外包装和缓冲/回填材料)和适宜的围岩地质体共同作用,来确保高放废物与生物圈的安全隔离。膨润土由于具有极低的渗透性和优良的核素吸附等性能而被国际上选作缓冲材料的基础材料。经过全国膨润土矿床筛选,我国高放废物深地质处置库缓冲材料的研究以产自高庙子膨润土矿床深部的钠基膨润土作为基本组成材料。本文介绍了高庙子膨润土矿床的地质特征以及高庙子钠基膨润土的基本特征。该膨润土与国外同类型材料相比具有蒙脱石含量高(75%左右)、杂质矿物相对较少的特点,该材料的系统和深入研究对于开发我国缓冲回填材料技术、确保高放废物的安全有效处置有重要意义。

Selection and basic properties of China's buffer materials for high level radioactive waste repository

Radioactive wastes arising from a wide range of human activities are in many different physical and chemical forms, contaminated with varying radioactivity. Their common feature is the potential hazard associated with their radioactivity, and their disposal is of vital importance to the protection of human environment. The geological disposal is commonly regarded in the world as the most reasonable and effective way to the safe disposal of high-level radioactive wastes. The conceptual model of geological disposal in China is based on a multi-barrier system that combines an isolated geological environment with an engineered barrier system. The buffer is one of the main engineered barriers for HLW repository. The buffer material is expected to maintain its low water permeability, self-sealing property, radio nuclides adsorption and retardation property, thermal conductivity, chemical buffering property, overpack supporting property, and stress buffering property over a long period of time. Benotite is selected as the main content of the buffer material that can satisfy the above requirements. GMZ deposit is selected as the candidate supplier for Chinese buffer materials of high level radioactive waste repository. This paper presents geological features of GMZ deposit and basic property of GMZ Na bentonite. GMZ bentonite deposit is a superlarge scale deposit with a high content of montmorillonite (about 75%), and GMZ-1, which is Na-bentonite produced from GMZ deposit, is selected as a reference material for Chinese buffer material study.