Thermal transient effects in fusion front wall/breeder blanket components

聚变前壁/增殖毯组件中的热瞬态效应

• 批准号: 2764904
• 金额: --
• 依托单位: University of Bristol
• 依托单位国家: 英国
• 项目类别: Studentship
• 财政年份: 2022
• 资助国家: 英国
• 起止时间: 2022 至 无数据
• 项目状态: 未结题
• 来源: https://gtr.ukri.org/projects?ref=studentship-2764904
• 关键词: Thermal; transient; effects; fusion; front

The high operating temperatures and nuclear radiation within a fusion reactor can significantly change the microstructure of its components, which in turn can change the material properties and mechanical behaviour. The materials chosen for fusion reactors have been specifically engineered to reduce the amount of induced radiation, but it is also important to understand how such materials will behave when exposed to the high temperatures of the fusion plasma. The plasma in a fusion reactor can reach temperatures of millions of degrees, and is kept controlled during operation using focused magnetic fields for containment. However, in the event of a loss of this containment it is possible for the plasma to contact with wall, leading to dramatic increases in temperature over short periods of time. The thermal transients will heat reactor materials above their desired operating conditions for very short spells but many times during operation. This could produce undesired and unpredicted microstructural evolution in components. This project would build on work at Bristol that has shown that even short periods high temperature (~750C) exposure can cause significant microstructural degradation of the Eurofer-97 stainless steel material used for structural support and cooling pipes [1]. This could affect mechanical properties and corrosion resistance, in turn leading to a shortening of component life. This PhD project will study the effect of very short-term thermal excursions on fusion front wall, divertor and breeder blanket materials and assess their effect on the microstructure and corrosion behaviour of the material.The student will build on existing experimental research at Bristol using a custom design vacuum laser exposure rig, that can expose materials to controlled thermal pulses for short (1-10s) thermal spikes using a CO2 laser. The student will adapt this experimental rig to enable faster cooling rates and shorter thermal spikes to more closely simulate the conditions of a plasma excursion. The system will then be used to study the microstructural evolution behaviour of fusion materials after repeated short-term thermal exposure. The project will investigate the thermal evolution and potential impacts from high numbers (reactor relevant) of thermal cycling above the desired operating temperatures on FW materials (e.g. ODS steel) and/or breeder substrate (Eu97) close to FW and interface joint. To getthe appropriate cycling rates (with fast cooling rates), investment in a new rig will likely by required. But such a rig could be used for other fusion relevant projects.Thermally exposed specimens will be characterised using scanning and transmission electron microscopy, x-ray diffraction and tomography to observe the change in the material microstructure with increasing heat exposure, and determine if any embrittlement or change in mechanical properties occur that might cause problems if used in a fusion reactor. The student will also compare experimental results to computational simulations of the phase diagram using CALPHAD-based modelling. There may also be opportunities to combine thermal exposures with the effects of irradiation and stress, and to assess similar conditions in weldments.

聚变反应堆内的高运行温度和核辐射会显着改变其部件的微观结构，这反过来又会改变材料性能和机械行为。为聚变反应堆选择的材料经过专门设计，以减少诱导辐射的量，但了解这些材料在暴露于聚变等离子体的高温时的行为也很重要。聚变反应堆中的等离子体可以达到数百万度的温度，并且在操作期间使用聚焦磁场进行控制。然而，在失去这种遏制的情况下，等离子体可能与壁接触，导致温度在短时间内急剧上升。热瞬变将在非常短的时间内但在操作期间多次将反应堆材料加热到其期望的操作条件以上。这可能会在部件中产生不期望的和不可预测的微观结构演变。该项目将建立在布里斯托的工作基础上，该工作表明，即使是短时间的高温（~ 750 C）暴露也会导致用于结构支撑和冷却管道的Eurofer-97不锈钢材料的显著微观结构退化[1]。这可能会影响机械性能和耐腐蚀性，进而导致部件寿命缩短。这个博士项目将研究非常短期的热漂移对聚变前壁、偏滤器和增殖包层材料的影响，并评估它们对材料微观结构和腐蚀行为的影响。学生将在布里斯托现有的实验研究基础上，使用定制设计的真空激光曝光装置，它可以使用CO2激光器将材料暴露于受控的热脉冲中，产生短（1- 10秒）的热尖峰。学生将调整这个实验装置，以实现更快的冷却速率和更短的热峰值，以更接近地模拟等离子体漂移的条件。然后，该系统将用于研究聚变材料在反复短期热暴露后的微观结构演变行为。该项目将调查热演变情况以及在所需操作温度以上的大量（与反应堆相关的）热循环对FW材料（例如消耗臭氧层物质钢）和/或靠近FW和界面接头的增殖衬底（Eu 97）的潜在影响。为了获得适当的循环速率（快速冷却速率），可能需要投资新的钻机。但是这样的装置也可以用于其他与聚变相关的项目。热暴露的样品将使用扫描和透射电子显微镜、X射线衍射和断层扫描来表征，以观察材料微观结构随着热暴露的增加而发生的变化，并确定是否发生任何脆化或机械性能变化，如果用于聚变反应堆，这些变化可能会导致问题。学生还将使用基于CALPHAD的建模将实验结果与相图的计算模拟进行比较。也可能有机会将联合收割机热暴露与辐照和应力的影响结合起来，并评估焊接件中的类似条件。