某花岗岩型铀矿床中铀系核素和类比元素迁移特征──高放废物处置库安全评价的天然类比研究

MIGRATION OF URANIUM-SERIES RADIONUCLIDES AND SOME ANALOGUE TRACE ELEMENTS AROUND A URANIUM DEPOSIT──A NATURAL ANALOGUE OF SAFETY ASSESSEMENT OF HIGH-LEVEL RADWASTE REPOSITORIES

某花岗岩型铀矿床中铀天然衰变系长寿命核素和类比微量元量，自该矿床５１Ｍａ前生成以来，未向周围花岗岩中发生远距迁移，铀矿体及近矿岩石至今仍处于化学封闭状态。矿石、岩石裂隙处局部出现有核素、元素迁移和沉淀，因裂隙细小且大多充填有粘土矿物等，迁移距离不足２５－３０ｍ，且仅发生在距今１０－１０６ａ及至今时距内。

According to the Chinese High-level Radwaste Management, it is assumed that the high-level radwaste will be deeply buried in a repository 1000 m in depth ia a granitic platen in Northwest China, which is similar to a granite-hosted uranium deposit located in southem China in many features. The study on the latter will provide valuable insight toward the eventual design and site selection of the high-level radwaste repository. Some uranium-series radionuclides, e. g., 234U ,238U, 230Th,232Thand.226Ra, and some trace elements in the ores and the host granite of the uranium deposit. were determined. The results indicated that the uranium deposit has kept being a close system since its formation before 51 Ma. The present geochemical analogue studies indicate that the combination of natural barriers. has been effective in isolating the uranium ore from the surface environment. Thus, disposing hight-level radwaste in a deep granite- hosted repository, in which there is a combination of several artificial barriers and natural barriers, will be safe..