中低放废物近地表处置库源项释放模式及模拟计算结果

SOURCE TERM MODEL OF LOW-INTERMEDIATE LEVELWASTE REPOSITORY AND THE SIMULATED CALCULATION

为了计算中低放废物近地表处置库源项释放速率，本文以某核电站处置场的概念设计为例，建立了一个简单而比较完整的源项释放模式。它包括水入渗模式、处置库混凝土顶盖的破损模式、金属桶腐蚀模式、核素从水泥固化体中的浸出释放模式及浸出核素在回填材料中的迁移模式。在模拟计算前，对处置的主要核素进行了筛选计算，筛选计算结果表明，￣（１３７）Ｃｓ、￣（９０）Ｓｒ、￣（６０）Ｃｏ、￣（６３）Ｎｉ和￣（２３９）Ｐｕ在常规条件下处置是安全的，而￣（１４）Ｃ可能是处置安全评价的关键核素，但经过采用适当的工程屏障可满足安全要求。

To evaluate radionuclides release rate from a near-surface disposal facility forLILW,a simple model was built on the basis of a specific repository design.The model in-cludes the submodels of water infiltration,concrete cap degradation,drum corrosion,nuclidesleaching from solidified waste form and nuclides migration in backfill material.Screening calculation was made for some the main nuclides and indicated that under normal condition￣(137)Cs,￣(90)Sr,￣(60)Co,￣(63)Ni and ￣(239)Pu would not cause safety problem and ￣(14)C might be the key nuclide for safety assessment.With a proper engineering barrier design the safety requirementscould be fulfilled.