许多希土元素,特别是Gd、Sm、Eu、Dy的热中子俘获载面很大。核燃料中如存在这些元素将影响中子的充分利用,含量较高时会影响核反应进行。一般说,含量不宜超过10~(-4)％量级,因此对其产品必须进行监测。核燃料中希土元素的分析方法主要有中子活化法、质谱法,X-射线激发光学萤光光谱法和原子发射光 Many rare earth elements, especially Gd, Sm, Eu, Dy thermal neutron capture surface is large. The presence of these elements in nuclear fuels will affect the full utilization of neutrons and at higher levels will affect nuclear reactions. In general, the content should not exceed the magnitude of 10 ~ (-4)%, so its products must be monitored. The main methods for the analysis of rare earth elements in nuclear fuel include neutron activation, mass spectrometry, X-ray fluorescence spectroscopy and atomic emission