TIMS测定辐照后Gd同位素比的方法研究

Determination of Gd Isotope Ratio in Irradiated Gadolinium by TIMS

建立了热电离质谱法(TIMS)测量天然及辐照后氧化钆同位素丰度比的检测方法。天然氧化钆制备成靶件,放入高通量工程试验堆(HFETR)预定孔道接受中子辐照,辐照时间共计91.3 h,反应堆功率为80 MW,辐照孔道中子注量率约为2×10^14 n·cm^-2·s^-1。辐照后靶件经切割、转运、溶解、制样与测量等过程,完成了对可燃中子毒物钆的辐照与测量,并对测量值进行了修正。数据结果表明,热电离质谱法对Gd辐照后检验的分析数据准确可靠,辐照后样品的后处理方法合理,钆的各同位素的丰度变化值前后吻合,且与中子吸收截面大小密切相关。本方法可用于铀钆混合燃料芯块和卸料元件组件中可燃毒物钆的同位素分析。获得的实测数据可反向用于理论计算修正,以期获得更优的反应堆堆芯设计方案。

A method for the determination of gadolinium isotope abundance ratio of irradiated gadolinium by thermal ionization mass spectrometry(TIMS)has been established.The natural gadolinium oxide was prepared into a target and placed in the preset channel of high flux engineering test reactor(HFETR)to receive neutron irradiation.The total irradiation time was 91.3 h,the reactor power was 80 MW,and the neutron flux rate of irradiated channel was about 2×10^14 n·cm^-2·s^-1.After irradiation,the radiation and measurement of gadolinium(Gd)of flammable neutron poisons were completed by cutting,transporting,dissolving,sampling and measuring the targets,then the measured values were corrected.The results showed that the analyzing date for the post-irradiation testing of Gd by TIMS was accurate and reliable.The post treatment method of the sample after irradiation was reasonable.The variation of the isotopic abundance of various gadolinium was consistent and closely related to the neutron absorption cross section.This method can be used for isotopic analysis of gadolinium in uranium/gadolinium mixed fuel pellets and unloading element.After the measured data are obtained,it can be used to revise the theoretical calculation in order to obtain better reactor core design scheme.