包气带中85Sr迁移的浓度双峰分布数值模拟研究

为了深入研究核素在地质介质中的迁移规律，为低中放废物近地表处置环境安全评价提供依据，开展了在黄土包气带人工喷淋条件下，８５Ｓｒ、６０Ｃｏ和１３４Ｃｓ的加速迁移试验经过两年多的示踪试验，发现８５Ｓｒ在迁移过程中，出现了浓度双峰分布．用单一对流弥散数值模型无法解释这一现象．基于“８５Ｓｒ以两种化学形态迁移”的假设，采用两种不同的吸附参数进行数值计算．结果表明，数值模拟与试验结果拟合得较好，得出８５Ｓｒ的两种化学形态的分配系数分别介于４００－８００ｍＬ／ｇ和３０－６０ｍＬ／ｇ．

Numerical modeling of 85Sr migration in aerated zone with the characteristic of double peak concentration distribution

The test of 85Sr migration in unsaturated loess under artificial sprinkling was conducted in order to study theradionuclides migration in geological media and to provide the basis for safety assessment of near surface disposal of lowand intermediate level radioactive waste. It is found from 2-year tracing test that the 85Sr concentration distribution hascharacteristic of double peak in its ingration process and can not be described typically by the numerical modeling ofadvection-dispersion. In this study,with the assumption of two forms of 85Sr in its migration, the numerical modeling wasdone and showed that the numerical simulation results agreed well with the in-situ test data. each form possessing differentcoefficients. The calculated distribution coefficients associated with the two forms of 85Sr are from 400 to 800 and 30 to 60mL/g respectively.