8 二次离子质谱测定二氧化钚微粒样品的钚同位素比值

含钚微粒中Pu的同位素组成分析是确定Pu的来源的重要信息，这对于核保障、反核走私具有重要意义。本工作研究利用二次离子质谱仪（SIMS）对PuO2微粒样品中的Pu同位素进行精确分析。     

扫描电子显微镜结合热电离质谱测定单微粒中铀同位素比值

单微粒铀同位素分析是核保障环境监测技术的重要手段。作为现阶段应用最可靠且广泛的微粒分析技术之一,裂变径迹-热电离质谱(FT-TIMS)技术需依赖反应堆辐照,分析步骤繁琐,效率较低。扫描电子显微镜结合热电离质谱(SEM-TIMS)在保持原有TIMS的高测量精密度的同时,由扫描电子显微镜结合X射线能量色散谱仪(SEM-EDX)完成含铀微粒的寻找和鉴别,由微操作系统进行微粒转移,缩短了分析流程,提高了分析效率。本文应用建立的SEM-TIMS分析方法对已知同位素组成的单分散铀氧化物标准微粒进行了测量,测量结果与其标称值一致。     

元素分析-同位素质谱测定δ15N和δ34S的信号强度响应特征

自然界中不同类型样品C、N和S元素含量以及C/N和C/S的差异极大,导致元素分析-同位素比值质谱仪(EA-IRMS)联机系统的进样量和检测信号强度的变化范围极大。进样量和信号强度对EA-IRMS测定δ¹⁵N和δ³⁴S的影响将导致样品测量结果具有较大的不确定性。为应对样品中目标元素含量低或样品稀缺等限制,本研究重点关注EA-IRMS测定δ¹⁵N和δ³⁴S的信号强度依赖性特征。结果表明,EA-IRMS在小元素进样量或弱信号强度条件下测定δ¹⁵N和δ³⁴S需要进行空白校正。在1.71～561.93μg N和3.74～100.62μg S的进样条件下,同位素标准物质δ¹⁵N和δ³⁴S的测定误差变化范围分别为0.18‰～0.54‰和0.21‰～0.88‰,测定精度变化范围分别为0.24‰～0.57‰和0.27‰～0.54‰。该联机系统对高C/N和C/S(>200)木材标准物质测定时,其δ¹⁵N平...     

高分辨氢同位素质谱仪的研制与应用

基于聚变核材料科研和生产、高温气冷堆产氚、氚放射性环境监测的需要设计了一套用于氢同位素分析的高分辨氢同位素质谱仪（HR-IRMS）,通过简单易操作的压强法配气系统,建立了氢氘氚配气装置。所研制的HR-IRMS仪器分辨率达2210,测量精密度达0.02%,相对原子质量范围为1~150。比对分析表明,其具有良好的运行稳定性和测定结果准确性,可实现氢同位素直接分析。     

质谱法测量碳同位素丰度在气体扩散法分离乙醇中的应用

乙醇是扩散分离碳同位素的一种可行的介质,为得到气体扩散法分离乙醇的分离系数,开展元素分析-同位素比质谱法(EA-IRMS)测量乙醇中碳同位素丰度在气体扩散分离实验中的应用研究。通过文献调研,本研究优化了乙醇样品的制备流程,发展了EA-IRMS用于乙醇碳同位素丰度测定的方法,进行了稳定性测试,实现了对乙醇样品碳同位素丰度的测量。基于气体扩散法的分离实验,获取多次分离实验中精料乙醇和贫料乙醇的碳同位素丰度,经公式推导可计算得到乙醇扩散分离碳同位素的基本全分离系数。本研究为未来开展以乙醇为介质扩散分离碳同位素实验提供了分析基础。     

质谱法测量碳同位素丰度在气体扩散法分离乙醇中的应用

乙醇是扩散分离碳同位素的一种可行的介质,为得到气体扩散法分离乙醇的分离系数,开展元素分析-同位素比质谱法(EA-IRMS)测量乙醇中碳同位素丰度在气体扩散分离实验中的应用研究。通过文献调研,本研究优化了乙醇样品的制备流程,发展了EA-IRMS用于乙醇碳同位素丰度测定的方法,进行了稳定性测试,实现了对乙醇样品碳同位素丰度的测量。基于气体扩散法的分离实验,获取多次分离实验中精料乙醇和贫料乙醇的碳同位素丰度,经公式推导可计算得到乙醇扩散分离碳同位素的基本全分离系数。本研究为未来开展以乙醇为介质扩散分离碳同位素实验提供了分析基础。     

四极质谱计测量天然水平氘氢丰度比

自制了高温铬还原制氢装置;探索了降低复合氢离子H3 对氘化氢离子HD 干扰的方法。以氘丰度为天然水平的国家一级标准水样中的两个样品作为标准,另外两个样品作为测试样品,在GAM400四极质谱计上探索了等氢分子离子H2 线性校正测量值的方法。利用双标准外标氘氢丰度比差值校准系数的方法对两个标准水样进行了测量,结果与国家标准值偏差为±0.1%,最终评估测量相对不确定度为0.8%。     

四极质谱计测量天然水平氘氢丰度比技术研究

自制了高温铬还原制氢装置，探索了降低H3+对HD+干扰的方法。以一套氘丰度为天然水平的国家一级标准水样中的两个样品作为标准，另外两个样品作为测试样品，在GAM400四极质谱计上探索了等H2+线性校正测量值的方法，利用双标准外标氘氢丰度比差值校准系数的方法对两个标准水样进行了测量，结果与国家标准值偏差为±0.1％，最终评估测量相对不确定度为0.8％。     

Development of New Type Ion Source of Quadrupole Type Mass Spectrometer for UF6 Analysis

A new type ion source including sample inlet pipe of quadrupole type mass spectrometer for analysis of UF₆ has been made. Fundamental characteristics of the ion source, such as pressure characteristic, flow rate, sensitivity of the ion source for UFG, inlet and evacuation characteristic were evaluated. The ion source showed good operational stability under low pressure and small flow rate, which were 1.0~2.0 Torr and 0.3~0.4 mg/h, respectively. Inlet characteristic was within 60s, evacuation characteristic to remove residual UF₆ less than 0.1% level was 15s. Sensitivity coefficient of the ion source was 0.5~1.0 Torr^-1. In consequence, it proved that the ion source had long life and memory effect was negligible small.

This ion source was also applied to measure ²³⁵U isotope ratio. Both precision and accuracy were within ±0.40% for UF₆ sample whose enrichment was more than 1.0%. It was clear that this ion source had good performances and it contributed to isotope ratio measurements with good accuracy.     

加速器质谱法测量含铀微粒中铀同位素比的方法研究

准确测定含铀微粒同位素比在核保障中有重要的应用价值。本文采用将含铀微粒溶解并加入高纯Fe粉烘干的方法制样,采用中国原子能科学研究院的HI-13串列加速器质谱测量靶样中的同位素比。通过对CRM铀系列同位素标准样品的分析表明,该方法可测定高于10^-5的²³⁶U/²³⁸U同位素比;对于²³⁵U/²³⁸U同位素比在10^-4～10^-1范围内的含铀微粒,²³⁵U/²³⁸U同位素比相对扩展不确定度均小于10%。     

Efficient Isotope Ratio Analysis of Uranium Particles in Swipe Samples by Total-Reflection X-ray Fluorescence Spectrometry and Secondary Ion Mass Spectrometry

A new particle recovery method and a sensitive screening method were developed for subsequent isotope ratio analysis of uranium particles in safeguards swipe samples. The particles in the swipe sample were recovered onto a carrier by means of vacuum suction-impact collection method. When grease coating was applied to the carrier, the recovery efficiency was improved to 48±9%, which is superior to that of conventionally-used ultrasoneration method. Prior to isotope ratio analysis with secondary ion mass spectrometry (SIMS), total reflection X-ray fluorescence spectrometry (TXRF) was applied to screen the sample for the presence of uranium particles. By the use of Si carriers in TXRF analysis, the detection limit of 22 pg was achieved for uranium. By combining these methods with SIMS, the isotope ratios of ²³⁵U/²³⁸U for individual uranium particles were efficiently determined.