AMS-UK: A UK Accelerator Mass Spectrometry Facility for Nuclear Fission Research

AMS-UK：英国用于核裂变研究的加速器质谱设施

基本信息

批准号：
EP/T01136X/1
负责人：
Malcolm Joyce
金额：
$ 355.57万
依托单位：
Lancaster University
依托单位国家：
英国
项目类别：
Research Grant
财政年份：
2019
资助国家：
英国
起止时间：
2019 至无数据
项目状态：
已结题

来源：
https://gtr.ukri.org/projects?ref=EP%2FT01136X%2F1
关键词：
AMS UK Accelerator Mass Spectrometry

项目摘要

Phase 2 of the National Nuclear User Facility is a significant investment in science and engineering facilities and apparatus to support nuclear fission research on radioactive samples in the UK. This proposal is submitted under this initiative and concerns a very sensitive technique for the assessment of a significant group of radioactive elements produced in nuclear reactors: the actinides. The actinides are amongst the heaviest known elements, formed as a result of neutron capture on uranium. They are all radioactive, to a greater or lesser degree, and several are very long-lived. The combination of their radioactivity and chemistry renders some significant radio toxins that have be managed and stored carefully. The most significant is plutonium, which is often present in the form of the isotope 239Pu and to a lesser extent, 238Pu, 240Pu, 241Pu, 242Pu and occasionally 244Pu.Plutonium is effectively extinct on Earth as a natural product of the Big Bang because its half life is too short to have survived. However, minuscule quantities are known to have formed in geological deposits that are naturally rich in uranium, via natural neutron capture processes on the most abundant uranium isotope, 238U, in these ores. Plutonium has been re-introduced to the environment, predominantly as a result of atmospheric nuclear weapons testing in the 1950-1990 period (fallout), but also as a result of nuclear reactor accidents (Chernobyl and Fukushima) and the dispersion of effluents from nuclear reprocessing activities: in the UK this is thought to be most significant due to activities at Sellafield and Dounreay.The high radio-toxicity of plutonium requires that materials contaminated by it are managed and stored very carefully, especially since large quantities are soils from contaminated land and building materials from contaminated structures. However, how do we discern what was there before, often in a wider context (from fallout and natural arisings in uranium-rich ores), from what has been dispersed locally? Simply 'detecting' plutonium is not sufficient because, whilst radioactive, it is usually dispersed at such minuscule levels there is not enough to provide enough radiation to detect it on a practical basis. Special samples can be made and the alpha radioactivity counted from these, but this does not allow individual isotopes to be discerned, which is an important requirement: fallout material is often rich in the heavier isotopes (242Pu and 244Pu) whereas material from nuclear reactors tends to be rich in 239Pu, 240Pu and 241Pu.In this proposal, we recommend investing in a recently-established capability to measure plutonium isotopes by their mass rather than their radioactivity. The isotopes are accelerated from a sample into which the plutonium has been extracted by dissolution, and dispersed in a magnetic field. They are ionised and collected in a particle detector where their position (as a result of the magnetic field deflection) and their rate of energy deposition are used to identify them, usually as a ratio of the rare isotope to an abundant alternative, where the latter can be introduced artificially to highlight the rare variant. This approach is called accelerator mass spectrometry. Until recently, this relied on large machines at particle accelerator facilities and was very expensive. Now, commercial systems are available that are smaller and cheaper, but the UK does not have one despite being the custodian of the largest stockpile of civil-separated plutonium. This proposal recommends that one of these is installed at Lancaster University, for external usage by the whole nuclear fission community. This is an important proposal because the UK Government committed to an agreement, the 'nuclear sector deal', which requires that businesses reduce the cost of decommissioning by at least 20%. Improved plutonium assay of contaminated materials will make a significant contribution to this aim.

国家核用户设施的第二阶段是对科学和工程设施和机构的重大投资，以支持英国放射性样品的核裂变研究。该提案是根据该计划提交的，并涉及一种非常敏感的技术，用于评估核反应堆中产生的重要放射性元件：actinides。阳离子是最重的已知元素之一，是由于铀上的中子捕获而形成的。它们都是放射性的，或者或多或少，而且有些是非常长的。它们的放射性和化学的结合提供了一些已仔细管理和储存的重要无线电毒素。最重要的是p是p，通常以同位素239pu的形式存在，在较小程度上，238pu，240pu，240pu，241pu，242pu，有时244pu.plutonium在地球上有效地悬而未决，因为它是大爆炸的自然产物，因为它的半大生命太短了，无法生存。但是，已知微量的数量是在自然富含铀的地质沉积物中形成的，这些矿石是通过自然中子捕获过程在这些矿石中最丰富的238U铀同位素上形成的。在1950年至1990年的大气核武器测试（辐射）中，以及由于核反应堆事故（精选和福岛）的结果，p池已重新引入了环境，主要是由于大气核武器测试的结果，也主要是由于核反应堆事故以及核重新认可活动的耗散性的结果：在UK中，卖出了众多的活动。 plut池要求对其受污染的材料进行管理和仔细的储存，尤其是因为大量的是受污染的土地和受污染结构的建筑材料的土壤。但是，我们如何从更广泛的环境（来自铀丰富的矿石中的辐射和自然出现）来辨别以前的情况，从本地分散的东西？简单地“检测” p是不够的，因为虽然放射性，但通常会在如此小的水平下散布，但不足以提供足够的辐射来实际检测它。 Special samples can be made and the alpha radioactivity counted from these, but this does not allow individual isotopes to be discerned, which is an important requirement: fallout material is often rich in the heavier isotopes (242Pu and 244Pu) whereas material from nuclear reactors tends to be rich in 239Pu, 240Pu and 241Pu.In this proposal, we recommend investing in a recently-established capability to measure p同位素通过其质量而不是放射性。同位素是从通过溶解提取并分散在磁场中的样品中加速的。它们被离子化并收集在粒子探测器中，在该粒子探测器中，它们的位置（由于磁场的挠度），并使用它们的能量沉积速率来识别它们，通常是稀有同位素与丰富替代方案的比例，可以在其中人工引入后者以突出稀有变体。这种方法称为加速器质谱法。直到最近，这还依赖于粒子加速器设施的大型机器，而且非常昂贵。现在，有较小且更便宜的商业系统，但尽管是公民分离的plut餐中最大的库存的托管人，但英国没有一个商业系统。该提案建议其中一个安装在兰开斯特大学，用于整个核裂变社区的外部使用。这是一项重要的建议，因为英国政府承诺达成协议，即“核部门交易”，该协议要求企业将退役成本降低至少20％。改善受污染材料的p lut子测定将为这一目标做出重大贡献。