针对200 L核废物桶分段γ扫描（SGS）过程中的效率刻度问题，提出了一种效率刻度函数模型，采用MCNP程序计算不同基质密度和γ射线能量条件下的离散断层效率，经过多元非线性回归获取函数参数，从而建立效率刻度函数，实现核废物桶SGS断层效率刻度。对核废物桶样品进行实验分析，结果表明：对于桶内基质分别为密度0.310 g·cm^?3的硅酸铝、密度0.595 g·cm^?3的木质纤维，桶内核素分别为活度3.110×10⁵ Bq的点源¹³⁷Cs、活度1.371×10⁵ Bq的点源⁶⁰Co，在桶内仅有单个点源存在的核素分布极端不均匀情况下，桶内核素活度重建误差在?37.68%～31.52%范围内。本文的方法能够准确有效实现核废物桶SGS断层效率矩阵计算，并确定核废物桶内放射性核素活度，满足实际检测要求。

In this work, an efficiency calibration function model is presented to calculate the efficiency of segment in segmented gamma scanning (SGS) for 200 L nuclear waste drum. Discrete SGS efficiencies are simulated with MCNP for different densities and gamma ray energies. Parameters of function are determined by using multivariate nonlinear regression method with the efficiencies. The SGS efficiency calibration function is constructed to calculate the efficiency matrix. Aluminum silicate with density of 0.310 g·cm^?3, wood fiber of 0.595 g·cm^?3, point sources ¹³⁷Cs with activity of 3.110×10⁵ Bq and ⁶⁰Co of 1.371×10⁵ Bq are used to construct samples of drum for SGS analysis. Result shows: for the extremely heterogeneous radioisotope distribution of only a point source placed at 8 different positions in the drum, errors of reconstructed activities are ?37.68%～31.52%. Overall, the reconstructed activity is in agreement with the true activity. This method effectively and accurately achieves SGS efficiency calculation and reconstruction of activity.