热表面电离质谱法测定钚氧化物中的钚同位素组成

采用热表面电离质谱法对钚氧化物中钚同位素丰度进行了测定。通过对钚氧化物样品预处理、离子源和分析器的真空控制、法拉第杯接收效率检测、测量过程中的信号强度大小控制、信号强度稳定性控制以及测量时间的控制等条件进行优化,确定了最佳预处理条件和测量条件,实现了钚氧化物中钚同位素组分的准确测定。在选定的条件下,测定了钚标准样品中的钚同位素丰度,主同位素239Pu和242Pu测量精密度(sr)均优于0.05%(n=6)。

Measurement of Plutonium Isotopic Compositions in Plutonium Oxide by Thermal Ionization Mass Spectroscopy

The study of the measurement of the plutonium isotopes abundance in the plutonium oxide using the thermal ionization mass spectroscopy (TIMS) is performed in the paper. The conditions such as pretreatment of the plutonium oxide sample, vacuum control of the ion source and analyzer, check of the receiving efficiency of the Faraday cups, the extent control of the signal intensity, the stability control of the signal intensity, the control of the measuring time and so on are optimized. The optimal conditions of pretreatment and measurment are determined, at which the accurate determination of plutonium isotopes components in the plutonium oxide is achieved. Under the selected condition, the plutonium isotopes abundance in the plutonium standard is obtained. Results show that the measuring precisions of the main isotopes ²³⁹Pu and ²⁴²Pu are better than 0.05%(n=6).