高放废物地质处置库安全评价的地球化学天然类比研究

A GEOCHEMICAL NATURAL ANALOGUE OF SAFETY ASSESSMENT ON GEOLOGICAL DISPOSAL DEPOSITARIES OF HIGH LEVEL RADWASTE

某铀矿床中水－岩反应的时间范围和强度，可通过对铀天然衰变系放射性不平衡的研究得到半定量化。该铀矿床在形成５１Ｍａ以来，由于水－岩反应较弱，矿石中铀系核素并未发生远距离迁移。铀矿体及近矿岩石至今仍基本处于化学封闭状态。虽然岩石裂隙附近局部发生核素微弱迁移和沉淀，但由于裂隙细小且大多充填粘土等，向上迁移不足３５ｍ，且仅发生在于１０６～１０４ａ及至今时段内。类比研究结果表明。

The time scale and intensity of the water rock interaction in a uranium deposit can be semi quantitatively assessed using uranium series disequilibrium. As the water rock interaction has been weak, no large range migration of the uranium series radio nuclides in the ores has occurred during 51 Ma since the deposit formed. Up till now, the uranium ore bodies and the granite around the ore bodies have chemically remained a close system. Although the local and weak removal and deposition of radio nuclides occurred in the granite near the fractures, the migration distance was no more than 35 m and only occurred in the time scale from 106 to 104 a or to present as the cracks in the rock are small and mostly filled with clay. This study shows that disposing high level radwaste in the fracture bearing granite without open faults is safe.