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

为实现英国到2050年实现零碳排放的目标，风能、太阳能、核能等二氧化碳零排放的替代能源发电是当前迫切发展的目标，以完全替代煤炭、石油、天然气等化石燃料的使用。和天然气。然而，广泛使用的核裂变反应堆存在许多问题，例如核废料处理和储存困难以及不可控链式反应的风险。另一方面，核聚变能源具有许多潜在的优势，例如比裂变能量高四倍、作为燃料的氢及其同位素丰富、放射性废物寿命短等。然而，聚变反应堆的发展对材料提出了很高的要求，因为这些材料必须承受高能级、高嬗变率、高温和高热机械应力。这带来了重大的材料设计挑战，需要设计和开发优质材料，以及创新、简便的制造路线，特别是对于聚变反应堆的第一壁结构和增殖毯。该结构不仅受到等离子体的辐照，还受到等离子体的中子轰击，以及高负荷的氦和氢，对结构材料造成严重损坏。目前，用于聚变反应堆第一壁和包层结构的潜在材料之一是低活化铁素体/马氏体（RAFM）钢，因为它具有优异的导热性、相对较低的热膨胀性和抗辐射引起的膨胀的能力。与其他材料相比，它具有氦脆性，并且易于商业化生产。然而，这些RAFM钢的性能限制其最高工作温度仅为550C，远低于650C的使用温度。此外，辐照会导致这些钢在较低使用温度（250-350℃）下硬化，在高温（450-550℃）下脆化，这也限制了它们的应用。因此，通过纳米颗粒和超细晶粒开发了第三代氧化物弥散强化（ODS）RAFM钢，成功地将工作温度提高到650℃。然而，ODS RAFM 钢的局限性在于，在大规模制造粉末以用于聚变反应堆的第一壁和包层结构时存在明显的困难。 ODS 钢还存在韧性至脆性转变温度较高的问题。这严重限制了它们的适用性。因此，仍然迫切需要开发新的RAFM钢，用于工作温度650℃的聚变反应堆结构材料，并且易于制造各种尺寸和结构。在该项目中，根据ODS RAFM钢，精细结构和高温稳定析出相将用于设计新型、可加工的 RAFM 钢。例如，金属间析出物和碳氮化物，它们在高温下比碳化物具有更低的粗化率，将是目标析出物；这些可以通过合金设计和相应的热处理来实现。此外，可以通过改进制造工艺来实现晶粒细化，例如使用奥氏成形，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再结晶形成纳米级亚晶。因此，该研究的最终目标将是生产新型 RAFM 钢，以供应球形托卡马克（STEP）。这需要在 2023 年至 2025 年之间进行材料选择，并在 2040 年通过聚变产生净电力。这还将支持英国成为聚变材料设计的世界领导者，并通过对突破性材料的尖端研究来发展这一突出地位。系统