Nuclear environmental forensics using radiocesium isotopes

使用放射性铯同位素进行核环境取证

• 批准号: 419819104
• 负责人: Professor Dr. Georg Steinhauser
• 金额: --
• 依托单位: Arbeitsgruppe Angewandte Radiochemie
• 依托单位国家: 德国
• 项目类别: Research Grants
• 财政年份: 2018
• 资助国家: 德国
• 起止时间: 2017-12-31 至 2021-12-31
• 项目状态: 已结题
• 来源: https://gepris.dfg.de/gepris/projekt/419819104?language=en
• 关键词: Nuclear; environmental; forensics; using; radiocesium

Nuclear forensics is the interdisciplinary science of the determination of the provenance, age or legal background of nuclear/radioactive materials. In the present proposal, this approach shall be expanded to environmental research questions. Whenever an environmental sample is contaminated with radionuclides (in particular radiocesium) from more than one source, it has been very difficult to establish the sources of each contamination and to determine the provenance of the contaminations. This challenge is exemplified by the Fukushima nuclear accident that caused releases of radioactive substances from 3 or 4 reactors, i.e. up to 4 different sources. Presently, it has proven to be very difficult to tell which source(s) contaminated an environmental sample with radiocesium, because typical radioanalytical methods as well as mass spectrometric methods (after acidic digestion) only reveal the integral contamination contained in the entire environmental sample. The sample hence may no longer exhibited a distinct signature (isotopic fingerprint) of one source if it has been contaminated by more than one source. Herein we propose nuclear forensics for the releases from Fukushima on a µm-scale to solve this long-existing problem. A significant amount of the radioactive releases occurred in the form of glassy, amorphous microspheres that may represent an archive of fission products from the molten nuclear fuel. These granules are chemically inert and virtually insoluble in water and are assumed to preserve their content for a long time. We propose the use of laser ablation triple-quadrupole inductively-coupled plasma mass spectrometry (LA-ICP-QQQ) to identify the isotopic radiocesium composition of single microspheres and reveal the provenance of each particle via the highly specific 135Cs/137Cs isotopic fingerprint that is clearly distinct for each of the sources. It is assumed that the microspheres have been "loaded" with their content inside the reactors and hence exhibit only minute concentrations of ubiquitous, interfering barium isotopes (135Ba and 137Ba, respectively) from the environment. ICP-QQQ is capable of suppressing this interference instrumentally via reaction gases. This method makes one of the most challenging radionuclide in environmental analysis finally measurable. An inter-method comparison between ICP-QQQ and instrumental neutron activation analysis is planned.In this project, an analytical protocol based on current questions around the Fukushima nuclear accident shall be developed, which shall then be available for environmental forensic research questions in Germany. This includes research related to the search for a nuclear waste repository, accident preparedness, or the decommissioning of nuclear facilities (identification of the source of a contamination).

核法证学是确定核/放射性材料的来源、年龄或法律的背景的跨学科科学。在本提案中，这一办法应扩大到环境研究问题。每当环境样本被来自多个来源的放射性核素（特别是放射性铯）污染时，就很难确定每种污染物的来源并确定污染物的来源。福岛核事故就是这一挑战的一个例子，该事故造成3或4个反应堆，即多达4个不同的来源释放放射性物质。目前，已经证明很难判断放射性铯污染环境样品的来源，因为典型的放射性分析方法以及质谱法（酸消化后）只能揭示整个环境样品中所含的整体污染。因此，如果样品被一个以上的来源污染，则可能不再显示出一个来源的独特特征（同位素指纹）。在此，我们建议对福岛核泄漏进行微米级的核取证，以解决这一长期存在的问题。大量的放射性物质以玻璃状、无定形微球体的形式释放出来，这可能是熔融核燃料裂变产物的档案。这些颗粒是化学惰性的，几乎不溶于水，并被认为可以长时间保存其内容物。我们建议使用激光烧蚀三重四极电感耦合等离子体质谱（LA-ICP-QQQ）来识别单个微球的同位素放射性铯成分，并通过高度特异性的135 Cs/137 Cs同位素指纹揭示每个颗粒的来源，该指纹对于每个来源都是明显不同的。假设微球已在反应器内“装载”了其内容物，因此仅显示出来自环境的普遍存在的干扰性钡同位素（分别为135 Ba和137 Ba）的微量浓度。ICP-QQQ能够通过反应气体抑制这种干扰。该方法使环境分析中最具挑战性的放射性核素之一最终可测量。计划对ICP-QQQ和仪器中子活化分析进行方法间比较。在该项目中，将根据福岛核事故的当前问题制定分析协议，然后将其用于德国的环境法医研究问题。这包括与寻找核废料储存库、事故准备或核设施退役（确定污染源）有关的研究。