The γ spectrum detecting system with CdZnTe (CZT) detector is one of effective methods for burnup measurement of spent fuel assembly. The detector efficiencies of the full energy peak for 137Cs and 134Cs were calculated with Geant4. The direction biasing sample method of source particle was used to improve calculation efficiency. The results provide a theoretical guide for the further burnup measurement.%利用碲锌镉(CZT)探测器组成的γ谱探测系统是一种测量乏燃料组件燃耗的较有效的方法.本文利用蒙特卡罗方法,借助于Geant4软件包计算在两种测量方式、多个准直高度条件下组件中137Cs和134 Cs的全能峰探测效率,对测量结果的正确评价分析具有一定意义.另外,采用偏倚抽样方法确定源粒子发射方向,极大提高了CZT探测器全能峰探测效率.
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