Salt-cooled High-temperature Reactors

与目前运行的轻水反应堆相比，熔盐冷却反应堆(也称为氟化物盐冷却高温反应堆--FHR)具有许多显著的优势。高温操作允许使用先进的动力循环(如超临界二氧化碳)实现高热力学效率的电力转换，并有可能直接使用核热来驱动工业过程、合成燃料的生产或用于特别远离热源的地区的区域加热。此外，熔盐的高热容，盐冷反应堆的低运行压力(尽管温度很高)和高溶解度以及对其他易挥发的裂变产物的保留将使盐冷反应堆避免了困扰轻水堆经济性的复杂和昂贵的安全系统。虽然在燃料循环和操作灵活性方面不如传统的熔盐反应堆有吸引力，但盐冷反应堆在安全性和经济性方面仍然保持着其主要优势。熔盐冷却剂与燃料的物理分离还允许更严格和更方便的冷却剂化学控制，这将允许解决结构材料腐蚀问题-经典熔盐反应堆最具挑战性的问题。到目前为止，所有已被检查的FHR设计都假设其堆芯中存在石墨，以提供堆芯结构或中子慢化，或两者兼而有之。从石墨芯的操作经验中已经知道，石墨在辐照后会经历尺寸变化，这对预测和建模具有挑战性，但最终会导致破裂，当它变得过于广泛时，最终会限制石墨芯的寿命。在EPSRC利用AGR技术进行的FHR项目过程中，人们发现，一些考虑的具有高功率密度和稳定的中子学行为的核心配置中含有很少的石墨，甚至根本没有石墨。消除石墨可能是一大优势，可能会简化堆芯的构造、维护并延长其使用寿命。这种不含石墨的堆芯的中子学、热工水力和安全性能以前从未被评估过。该项目的目标是开发无石墨FHR的计算分析模型，并确定最有希望的配置(几何结构和材料的组合)，在满足所有主要安全限制标准的同时，最大化堆芯功率输出和燃料消耗。

Molten salt cooled reactors (also known as Fluoride salt-cooled High-temperature Reactors - FHR) offer a number of significant advantages compared to currently operating LWRs. High temperature operation allows achieving high thermodynamic efficiency of power conversion using advanced power cycles, such as supercritical CO2, as well as a possibility of using nuclear heat directly to drive industrial processes, production of synthetic fuels, such as hydrogen or for district heating of areas located particularly far away from the heat source.Furthermore, high heat capacity of molten salts, their low operating pressure (despite high temperature) and high solubility and retention of otherwise volatile fission products would allow the salt-cooled reactors to avoid complicated and costly safety systems which plague the economics of LWRs.While not as attractive as the classical molten salt reactors with fuel dissolved in the molten salt in terms of fuel cycle and operational flexibility, salt-cooled reactors still retain their major advantages in safety and economics mentioned above. Physical separation of molten salt coolant from the fuel also allows tighter and more convenient coolant chemistry control which would allow addressing the structural materials corrosion problem - the most challenging issue of classical molten salt reactors.All FHR designs that have been examined so far assumed the presence of graphite in their cores in order to provide the core structure, or neutron moderation, or both. It has been known from operational experience with graphite cores that the graphite undergoes dimensional changes with irradiation which are challenging to predict and model, but which eventually lead to cracking and, when it becomes too extensive, ultimately limit the lives of graphite cores.In the course of the EPSRC project on FHR leveraging AGR technologies, it was discovered that some of the considered core configurations with high power density and stable neutronic behaviour had minimal or no graphite at all. Eliminating graphite could be a major advantage, potentially simplifying the construction, maintenance and extending lifetime of the core. The neutronic, thermal-hydraulic and safety performance of such cores without graphite have never been assessed previously. Theobjective of this project is to develop computational analysis model for graphite-free FHR and identify the most promising configuration (a combination of geometry and materials) which would maximise the core power output and fuel burnup, while meeting all the major safety limits criteria.