Linking Microstructure to Neutron Irradiation Defects in Advanced Manufacture of Steels

英国计划从萨默塞特郡欣克利角的两座机组开始建造一批新的核电站。英国政府最近还在2015年秋季声明中宣布，将拨出2.5亿英镑用于创新核技术。更具体地说，英国将投资小型模块化反应堆设计。大型反应堆和许多小型模块化反应堆的设计都是基于一种叫做压水反应堆的反应堆类型。这些反应堆设计有一个钢制的反应堆压力容器来包裹核燃料，并作为一个关键的屏障，以防止放射性有毒物质释放到环境中。容器的完整性对反应堆的安全和持续运行至关重要。不幸的是，核燃料的中子辐照会在钢的40-60年设计寿命期间对其造成损害。因此，了解中子损伤对这些钢的作用是在设计寿命之后继续运行的关键。本工作方案将在澳大利亚卢卡斯高地的OPAL试验反应堆研究中子辐照损伤下常用的反应堆压力容器锻造等级钢（A508级3）。这些钢将采用核反应堆中不常用的工艺制造，即粉末材料的热等静压（HIP），然后使用电子束（EB）焊接。这些新的制造工艺有可能用于制造未来小型反应堆设计的反应堆压力容器的部件。从锻造材料的电弧焊改为HIPed材料的电弧焊，对材料的中子辐照响应有何影响，目前还没有相关的资料。在这种情况下，材料的化学性质保持不变，因此关键变量是材料的所谓“微观结构”。计划对OPAL反应堆的样品进行长达1年的辐照，以达到相当于反应堆运行40-60年的中子脆化剂量。辐照后的材料将在澳大利亚核科学技术组织的热室中进行机械测试，然后运往英国UKAEA Culham站点的新材料研究设施。在这里，它将通过最近安装在牛津大学的新型LEAP 5000原子探针上的原子探针断层扫描，曼彻斯特大学的化学- stem透射电子显微镜，以及伦敦帝国理工学院和曼彻斯特大学开发的原子尺度模型，为最先进的表征做准备。该项目还将得到国家核实验室和罗尔斯·罗伊斯公司的管理和投入，并与新南威尔士大学、加州大学圣巴巴拉分校和橡树岭国家实验室建立国际联系。这项工作的总体成果将大大提高对中子辐照如何影响HIP和EB焊接制造的钢材的机理和模型的理解，从而为英国培养新一代工程师，他们可以研究辐照材料，并帮助指导使用这些技术来建造未来的小型反应堆设计。它还将成为重建物理和知识基础设施的关键驱动力，用于处理中子辐照钢，这在英国已经缺失了一代人。

The UK plans to build a new fleet of nuclear power plants starting with two units at Hinkley Point in Somerset. The UK government has also recently announced in the autumn 2015 statement that £250M will be set aside for in innovative nuclear technologies. More specifically it has stated that the UK will invest in small modular reactor designs. The large reactors and many small modular reactor designs are based around a reactor type called a pressurised water reactor. These reactor designs have a steel reactor pressure vessel to enclose the nuclear fuel and act as a key barrier to the release of radiotoxic materials to the environment. The integrity of the vessels is paramount to the safety and continued operation of the reactor. Unfortunately, neutron irradiation from the nuclear fuel damages the steels over their 40-60 year design life. Understanding the role of neutron damage to these steels is therefore key to continued operation beyond the design life. This programme of work will study commonly used reactor pressure vessel forging grade steels (A508 class 3), under neutron irradiation damage, at the OPAL test reactor, at Lucas Heights in Australia. The steels will be manufactured by processes not commonly used in nuclear reactors i.e. hot isostatic pressing (HIP) of powdered material and then welded using electron beams (EB). These new manufacturing processes could potentially be used to manufacture parts for the reactor pressure vessels of future small reactor designs. As yet there is no information on how changing the manufacturing routes from arc welding of forged material to EB welding of HIPed material will change the neutron irradiation response of the material. In this case the chemistry of the material remains unchanged so the key variable is the so-called "microstructure" of the material.It is planned to irradiate samples, at the OPAL reactor, for up to 1 year, to achieve doses of neutron embrittlement equivalent to 40-60 years reactor operation. The irradiated material will then be mechanically tested, in hot cells, at the Australian Nuclear Science and Technology Organisation before material is shipped to the new Materials Research Faclility at UKAEA Culham site in the UK. Here, it will be prepared for state-of-the-art characterisation, by atom probe tomography on the new LEAP 5000 atom probe recently installed at Oxford University, Chemi-STEM transmission electron microscopy at Manchester University, together with atomic scale models developed at Imperial College London and Manchester University. The project will also have management and input from the National Nuclear Laboratory and Rolls-Royce and international links to the University of New South Wales, University of California Santa Barbara and Oak Ridge National Laboratory.The overall output from this work will be much improved mechanistic understanding and models of how neutron irradiation effects steels manufactured by HIP and EB welding, lead to a new generation of engineers in the UK who can perform work on irradiated materials and help direct the use of such technologies for the building of future small reactor designs. It will also be a crucial driver in the effort to rebuild the physical and knowledge based infrastructure, for dealing with neutron irradiated steels, that has been missing for a generation in the UK.