燃料元件中^(235)U丰度的快中子诱发裂变测量方法研究

Measurement Methods Study on Determining the ^(235)U Abundance in the Fuel Elements by fast Neutron Induced Fission

铀同位素丰度分析是确保核燃料元件在堆中安全可靠运行非常重要的质量控制环节。本文从裂变产额质量分布曲线图中,选取位于双驼峰曲线两翼的、裂变产物的产额随可裂变核素的不同有较大的变化的核素^(88)Rb、^(107)Rh、^(135)I作为测量对象,绘制了平均裂变产额比Y_((88 Rb))/Y_((107 Rh)、Y_(88 Rb)/Y_(135 I)与铀丰度之间的关系曲线。利用两条工作曲线对不同堆型元件的模拟样品进行了分析,并就元件包壳对分析结果的影响进行了理论和实验研究。为了验证方法的准确性,分别对3.03%的模拟样品测量了各5次,相对标准偏差(RSD)均小于5%。

Determining the 235U abundance ratio of fuel pins is a significant stage among quality control in safe operations of reactor. 88Rb.107 Rh.135 I were choosed as analytic target. Relationship graphics of fission yield ration Y88Rb/Y107Rh,Y88Rb/Y135I VS 235U were polted. The simulated fuel element samples of different reactor were analyzed by working curve, and carried on theoretical analysis and experimental research on affection of measurement result by fuel element cladding. In order to testify the accuracy of the method, the simulation sample of 3. 030/4o was measured 5 times respectively, relative standard deviation（RSD） of all tests was less than 5 %.