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CHaracterisation, Imaging and MaPping of fuel debris for safe retrieval (CHIMP)

用于安全检索的燃料碎片的表征、成像和绘图 (CHIMP)

基本信息

批准号：
EP/R01924X/1
负责人：
Claire Louise Corkhill
金额：
$ 32.27万
依托单位：
University of Sheffield
依托单位国家：
英国
项目类别：
Research Grant
财政年份：
2017
资助国家：
英国
起止时间：
2017 至无数据
项目状态：
已结题

来源：
https://gtr.ukri.org/projects?ref=EP%2FR01924X%2F1
关键词：
CHaracterisation Imaging MaPping fuel debris

项目摘要

This research is a joint UK and Japan effort to support ongoing clean-up operations at the Fukushima Daiichi Nuclear Power Plant (NPP). On March 11 2011, the tsunami that engulfed the Fukushima Daiichi NPP resulted in a loss of coolant accident and the partial meltdown of boiling water reactor Units 1 - 3. Immediately after the meltdown, seawater was injected into the high-temperature reactor cores for emergency cooling, however this was not sufficient and temperatures rose in excess of 2000C, causing pellets of UO2 nuclear fuel to melt and react with steam-oxidised zircaloy fuel cladding. The resulting material is highly hazardous and comprises a mixture of UO2 fuel, zirconium from the cladding and other melted reactor components, such as concrete and steel from the fuel pressure containment vessel. These materials are known as fuel debris and corium and are highly radioactive since they also incorporate fission products and minor actinides (e.g. plutonium) from the fission of the fuel. Since the accident, water has been continuously injected to the reactor, which has successfully cooled the fuel debris and corium. In this so-called "stable cold shutdown condition", analysis of coolant water effluent has been shown to contain plutonium, which indicates that the fuel debris is being dissolved. This has prompted significant efforts to retrieve the fuel debris and corium from the reactors, but before any plans for retrieval can be made, and technologies selected to safely undertake the retrieval operations, it is necessary to understand: 1) the chemical and physical properties of the fuel debris and corium; and 2) where the fuel debris and corium reside within the reactor.Because this material is not found in 'normal' nuclear decommissioning operations, and because it is not possible to enter the reactor to take samples, or to locate its position due to the extreme radiation field, other solutions are required. In this research project, we will make surrogate fuel debris and corium materials using UO2 doped with "cold" fission product analogues (e.g. stable isotopes), melted together with zirconium cladding and other reactor component materials (e.g. concrete and steel). In comparison with real fuel debris and corium, these will be safe to handle in the laboratory. By analysis of these materials, which will be the most realistic fuel debris and corium simulants created to date, we will build an understanding of their properties, which will support the choice of decommissioning methodologies (e.g. which type of robot and cutting tool) and how to handle the materials once they have been retrieved from the reactor. These materials will also be used to validate two important techniques currently under development by our Japanese project partners to retrieve fuel debris and corium from the reactors. The first is an on-site remote 3D imaging technique, capable of identifying the type of radioactive elements in any given piece of fuel debris or corium within the reactor, without direct contact. It is proposed to test this method during our project at the Fukushima Daiichi NPP. The second is a statistical mapping model, which will use input from the characterisation of our simulant fuel debris and corium materials, combined with data from the gamma radiation emission from the fuel debris within the Fukushima Daiichi NPP, to make a predictive map of where the fuel debris and corium reside within the reactor. This model, our materials and the collaboration between UK and Japan partners in this project, will strongly support the planning and implementation of safe fuel debris retrieval operations, which are due to begin in 2021.

这项研究是英国和日本共同努力，以支持福岛第一核电站（NPP）正在进行的清理行动。2011年3月11日，席卷福岛第一核电站的海啸导致冷却剂流失事故和沸水反应堆1 - 3号机组部分熔毁。熔毁后，海水立即注入高温反应堆堆芯进行紧急冷却，但这并不足够，温度上升超过2000摄氏度，导致二氧化铀核燃料芯块熔化并与蒸汽氧化的镍铬合金燃料包壳反应。所产生的材料是高度危险的，包括UO 2燃料、来自包壳的锆和其他熔化的反应堆部件（例如来自燃料压力安全壳的混凝土和钢）的混合物。这些物质被称为燃料碎片和堆芯熔化物，具有高度放射性，因为它们还含有来自燃料裂变的裂变产物和次要锕系元素（如钚）。自事故发生以来，水一直被注入反应堆，成功地冷却了燃料碎片和堆芯熔化物。在这种所谓的“稳定冷停堆条件”下，对冷却水流出物的分析表明含有钚，这表明燃料碎片正在溶解。这促使人们作出重大努力，从反应堆中回收燃料碎片和堆芯熔化物，但在制定任何回收计划和选择安全进行回收作业的技术之前，有必要了解：1）燃料碎片和堆芯熔化物的化学和物理性质; 2）燃料碎片和堆芯熔化物在反应堆内的位置。由于这种材料在“正常”的核退役操作中是找不到的，而且由于不可能进入反应堆取样，或者由于极端辐射场而定位其位置，则需要其它解决方案。在本研究项目中，我们将使用掺有“冷”裂变产物类似物（如稳定同位素）的二氧化铀，与锆包壳和其他反应堆部件材料（如混凝土和钢）一起熔化，制造替代燃料碎片和堆芯熔化材料。与真实的燃料碎片和堆芯熔化物相比，在实验室中处理这些碎片是安全的。通过对这些材料的分析，这将是迄今为止最真实的燃料碎片和堆芯熔化模拟物，我们将建立对其属性的理解，这将支持退役方法的选择（例如，哪种类型的机器人和切割工具）以及一旦从反应堆中取回材料，如何处理它们。这些材料还将用于验证我们的日本项目合作伙伴目前正在开发的两项重要技术，以从反应堆中回收燃料碎片和堆芯熔化物。第一种是现场远程3D成像技术，能够在没有直接接触的情况下识别反应堆内任何给定的燃料碎片或堆芯熔化物中的放射性元素的类型。建议在福岛第一核电站的项目中测试该方法。第二个是统计映射模型，它将使用我们的模拟燃料碎片和堆芯熔化物材料的特性输入，结合来自福岛第一核电站内燃料碎片的伽马辐射发射数据，以制作燃料碎片和堆芯熔化物在反应堆内的位置的预测图。该模型、我们的材料以及英国和日本合作伙伴在该项目中的合作，将有力地支持定于2021年开始的安全燃料碎片回收行动的规划和实施。

项目成果

期刊论文数量（10）

专著数量（0）

科研奖励数量（0）

会议论文数量（0）

专利数量（0）

Chemical state mapping of simulant Chernobyl lava-like fuel containing material using micro-focused synchrotron X-ray spectroscopy.

DOI：
10.1107/s1600577521007748
发表时间：
2021-11-01
期刊：
Journal of synchrotron radiation
影响因子：
2.5
作者：
Ding H;Dixon Wilkins MC;Mottram LM;Blackburn LR;Grolimund D;Tappero R;Nicholas SL;Sun S;Corkhill CL;Hyatt NC
通讯作者：
Hyatt NC

Synthesis, characterisation and preliminary corrosion behaviour assessment of simulant Fukushima nuclear accident fuel debris

模拟福岛核事故燃料碎片的合成、表征及初步腐蚀行为评估