脉冲柱法研究碘在北山花岗岩中的迁移

Migration of Iodine in Beishan Granite Studied by Inject-Pulse Column Method

129I是一重要的裂变产物,其在环境中的行为受到人们的重视。本工作利用脉冲柱法研究了125I(作为129I的替代物)在北山花岗岩中的迁移情况。实验结果表明,对流-水力学弥散是碘迁移的主要机制。碘的弥散系数D随流速的增加而增加,随淋洗液pH的增加而减小。D随pH的变化趋势与岩粉表面的电荷变化吻合。当流速为0.07mL.min-1、pH=8.0时,D=3.29×10-5 m2.min-1,和已有的实验结果相符,验证了弥散度只与介质有关这一结论。

129I is an important fission product which is easy to be released into the environment by the nuclear power plants.Its movement in environment causes a lot of attention all around the world.In this work,the migration of 125I（as a substitute of 129I） in Beishan granite was studied by an inject-pulse column method.The results show that the dominant mechanisms of iodine migration are convection and dispersion.The dispersion coefficient（D） of iodine increases with the increase of the flow velocity or the decrease with pH.The change tendency of D with pH is coincide with the surface charge distribution of Beishan granite.D is 3.29×10-5 m2·min-1 when flow velocity is 0.07 mL·min-1 and pH is 8.0.This result verifies the conclusion that dispersion coefficient only relates to the migration media.