Process design of new reduced activation ferrite martensite (RAFM) steels for nuclear fusion reactors

核聚变反应堆用新型低活化铁素体马氏体（RAFM）钢的工艺设计

• 批准号: EP/X030652/1
• 负责人: Peng Gong
• 金额: $ 61.26万
• 依托单位: Newcastle University
• 依托单位国家: 英国
• 项目类别: Fellowship
• 财政年份: 2024
• 资助国家: 英国
• 起止时间: 2024 至 无数据
• 项目状态: 未结题
• 来源: https://gtr.ukri.org/projects?ref=EP%2FX030652%2F1
• 关键词: Process; design; new; reduced; activation

To achieve the UK zero carbon emission target by 2050, alternative energy generation with zero CO2 emission, such as wind, solar, and nuclear energy, is now the target of urgent development to completely replace the use of fossil fuels such as coal, oil, and natural gas. However, the widely used nuclear fission reactors have many issues, for example, the difficulty of nuclear waste treatment and storage and the risk of uncontrolled chain reactions. On the other hand, nuclear fusion energy has many potential advantages, for example, four times higher energy than fission, abundant hydrogen and its isotopes as the fuel, and the short lifespan of the radioactive waste products. However, the development of fusion reactors puts a high demand on materials, as these must withstand high energy levels, high transmutation rates, high temperatures, and high thermomechanical stresses. This brings major material design challenges and requires the design and development of superior materials, along with innovative, facile, manufacturing routes, especially for the first wall structures and breeder blanket of fusion reactors. The structure is not only irradiated by the plasma but also undergoes neutron bombardment from the plasma, as well as high loadings of helium and hydrogen, which causes serious damage to the structural materials. Currently, one of the potential materials designed for the first wall and blanket structures on the fusion reactors is the reduced activation ferritic/martensitic (RAFM) steels, due to the superior thermal conductivity, relatively low thermal expansion, and resistance to radiation-induced swelling and helium embrittlement, as well as the easy commercial process, compared to other materials. However, the properties of these RAFM steels restrict their maximum operating temperature to only 550C, which is much lower than the service temperature of 650C. Moreover, irradiation induces the hardening of these steels at lower service temperatures (250-350C) and embrittlement at high temperatures (450-550C), which also restricted their application. Thus, the 3rd generation oxide dispersion strengthened (ODS) RAFM steels have been developed through nanoparticle and ultra-fine grains, which successfully increase the operating temperature to 650C. However, the limitation of the ODS RAFM steels is the obvious difficulty in powder manufacturing at a sufficient scale to be used in the first wall and blanket structures in fusion reactors. ODS steels also have a problem with a high ductile to the brittle transition temperature. This severely limits their applicability. Thus, there is still an urgent need to develop new RAFM steels for the structure materials on fusion reactors with a service temperature of 650C and easy manufacturing to various scales and structures.In this project, according to ODS RAFM steels, the guiding principles of a fine structure and a high-temperature stable precipitate phase will be used to design new, processable, RAFM steels. For example, the intermetallic precipitates and carbonitrides, which have a lower coarsening rate than carbides at high temperatures, will be the target precipitates; these can be achieved through alloy design with corresponding heat treatment. Moreover, grain refinement can be achieved through the modification of the manufacturing process, for example, by using ausforming, which will produce an extremely high dislocation density. Subsequently, during heat treatment, these dislocations will form nanoscale subgrains through recovery and recrystallization. Thus, the ultimate goal of the research will be to produce new RAFM steels for supply to the spherical tokamak (STEP). This requires advances to allow materials selection between 2023 to 2025 and provision to produce net electricity from fusion in 2040. It will also support the UK to be the world leader in fusion materials design and develop this prominent position through cutting-edge research on groundbreaking material systems

为了达到英国零碳排放目标，到2050年，替代二氧化碳发射（例如风能，太阳能和核能）的替代能源产生现在是紧急开发的目标是完全取代使用化石燃料，例如煤炭，石油和天然气。但是，广泛使用的核裂变反应器有许多问题，例如，核废料处理和储存的难度以及不受控制的链反应的风险。另一方面，核融合能具有许多潜在的优势，例如，能量是裂变，丰富的氢及其同位素作为燃料的四倍，以及放射性废物产物的寿命短。但是，融合反应器的发展对材料的需求很高，因为这些必须承受高能级，高透射率，高温和高热机械应力。这带来了主要的材料设计挑战，并需要设计和开发优质材料，以及创新的，易于的制造路线，尤其是对于融合反应堆的第一壁结构和育种层覆盖物。该结构不仅被血浆照射，而且还会受到血浆中的中子轰击，以及氦气和氢的高负载，这对结构材料造成了严重破坏。目前，融合反应器上为第一壁和毯子结构设计的潜在材料之一是，由于有效的导热率，相对较低的热膨胀以及对辐射诱导的膨胀和氦气额的耐药性，与其他材料相比，激活铁素体/马氏体（RAFM）钢减少了。但是，这些RAFM钢的特性将其最大工作温度限制在仅550℃，远低于650c的使用温度。此外，辐照在较低的服务温度（250-350c）和高温（450-550C）下诱导这些钢的硬化，这也限制了它们的应用。因此，已经通过纳米颗粒和超细晶粒开发了第三代氧化物分散剂（ODS）RAFM钢，这些晶粒成功将工作温度成功提高到650c。但是，ODS RAFM钢的局限性是粉末制造的明显困难，足以在融合反应堆中使用在第一壁和毯子结构中。 ODS钢也存在较高的延性过渡温度的问题。这严重限制了他们的适用性。因此，迫切需要开发新的RAFM钢，用于融合反应器上的结构材料，其使用温度为650℃，并易于制造到各种规模和结构。例如，在高温下的金属间沉淀物和碳依思甲酸酯的变形速度低于碳化物。这些可以通过合金设计通过相应的热处理来实现。此外，可以通过使用Ausforming来修改制造过程来实现谷物的细化，这将产生极高的位错密度。随后，在热处理过程中，这些位错将通过恢复和重结晶形成纳米级亚细胞。因此，该研究的最终目标是生产新的RAFM钢，以供应球形Tokamak（步骤）。这需要允许在2023年至2025年之间进行材料的选择，并在2040年从融合中产生净电力。它还将支持英国成为融合材料设计的世界领导者，并通过对开创性材料系统的最先进的研究来发展这一重要位置