氚化水放射性活度的绝对测量

液体闪烁计数器具有无自吸收、制源简单、操作简便等特点,测量氚化水具有一定优势。利用液闪CIEMAT/NIST方法和三双符合比(TDCR)方法校准氚化水的比活度,旨在为氚化水标准物质的研制提供定值手段。以54 Mn作为示踪核素应用CIEMAT/NIST方法标准化氚化水比活度,合成标准不确定度为0.80%。液闪TDCR方法应用装配有3个光电倍增管的计数器,根据测量的符合信息直接计算得到探测效率,绝对测量氚化水比活度,合成标准不确定度为0.66%。应用这两种方法测量了同一组氚化水淬灭系列源,测量结果 En数检验满意。

Absolute Measurement of Activity of Tritiated Water

Liquid scintillation (LS )counting has advantages in noself-absorption,simple sample preparation,and relatively easy application tomany radionuclides,especially for 3 H which emits low energyβrays.The aim of this work is to calibrate the specific activity of the standard reference material of tritiated water to be developed,and the CIEMAT/NIST and TDCR methods were studied.The CIEMAT/NIST method with 54 Mn efficiency tracing was applied to standardize tritiated water on a Packard Tri-carb 3100TR spectrometer,and the combined standard uncertainty was 0. 80%.The triple to double coincidence ratio (TDCR) efficiency calculation method requires a special LS-counter equipped with 3 photomultiplier tubes (PMTs)in coincidence,and could determine the specific activity through the informa-tion of coincidence counts.The tritiated water was also absolutely measured by the TDCR method,and the combined standard uncertainty is 0. 66%.The results determined by the two methods are consistent with each other within En criterion.