AGR Technologies for Enabling Molten Salt-cooled Reactor Designs

高温反应堆通常使用氦气作为冷却剂。然而，与液体冷却剂相比，气体的主要缺点是它们的体积热容低，这最终导致反应堆功率密度低，因此经济性差。熔盐由于其上级传热性能，可以显著提高堆芯功率密度，因而成为高温反应堆中氦冷却剂的主要替代物。此外，在高温（约700 ℃）下运行将导致高功率转换效率，并允许将反应堆热量用于各种工业过程。此外，熔盐的高沸点（>1,200 ℃）将允许在低压下操作的设计，这将降低反应堆容器的成本，进一步有助于该概念的经济吸引力。熔盐冷却高温反应堆设计的另一个共同特征是使用高度坚固的包覆颗粒TRISO燃料和石墨减速剂。结合盐冷却剂的化学惰性和高热容，这些特性使其具有出色的安全性。最近提出的这种系统的变体之一是氟化物盐冷却高温反应堆（FHR）。存在许多实施该概念的选择，这些选择依赖于结合不同的燃料形式、冷却剂盐和关键部件的配置。到目前为止，这个巨大的设计空间中只有一小部分被探索过。具有某些燃料设计的FHR可以潜在地采用在英国设计并成功运行多年的先进气冷堆（AGR）的许多特征。利用现有的AGR技术和运行经验将大大降低FHR的开发成本，并提高其经济吸引力。该项目将开发一个高热能商业规模的FHR，利用和适应AGR的现有技术，例如换料策略，组件布局和维护方法，以及适应使用高温气冷堆的TRISO颗粒燃料。该项目将确定燃料、盐冷却剂和堆芯配置在经济性能和安全性方面最具吸引力的组合。该项目将由位于洛厄尔的马萨诸塞州大学牵头，与马萨诸塞州理工学院、英国剑桥大学和作为工业合作伙伴的阿海珐合作。美国大学将为基线设计进行堆芯和燃料循环战略的设计空间探索，而剑桥大学将侧重于AGR型燃料配置的替代方案。工业合作伙伴将领导经济分析工作，并为制定加油和维护策略以及安全分析任务做出贡献。

High temperature reactors most commonly use He gas as a coolant. The main disadvantage of gases however is their low, compared to liquid coolants, volumetric heat capacity, which ultimately leads to low reactor power density and hence inferior economics. Molten salts are leading candidates to replace the helium coolant in high temperature reactors due to superior heat transfer properties that would allow substantial increase in the core power density. In addition, operation at high temperature (around 700 C) would lead to high power conversion efficiency and allow the use of the reactor heat for various industrial processes. Moreover, high boiling point of molten salts (>1,200 C) would allow designs that operate at low pressure, which should reduce the cost of the reactor vessel, further contributing to economic attractiveness of the concept. Another common feature of molten salt-cooled high temperature reactor designs is the use of highly robust coated-particle TRISO fuel and a graphite moderator. In combination with chemical inertness and high heat capacity of the salt coolant, these features make excellent safety case.One of the recently proposed variants of such system is Fluoride salt-cooled High temperature Reactor (FHR). Many options exist for the implementation of the concept which rely on combining different fuel forms, coolant salts and configurations of key components. Only a small fraction of this vast design space has been explored so far. FHRs with certain fuel designs can potentially adopt many features from the Advanced Gas cooled Reactors (AGRs) designed and being successfully operated in the UK for many years. Taking advantage of the existing AGR technology and operating experience would substantially reduce the development costs of FHRs and improve their economic attractiveness.This project will develop a high thermal power commercial-scale FHR leveraging and adapting existing technology from the AGR, such as refuelling strategy, layout of components and maintenance approaches, as well as adapting the use TRISO particles fuel from the High Temperature Gas-cooled Reactors. The project will identify the most attractive combination of fuel, salt coolant and core configuration with respect to economic performance and safety.The project will be led by the University of Massachusetts at Lowell in collaboration with Massachusetts Institute of Technology, University of Cambridge, UK and AREVA as an industrial partner. The US Universities will perform the design space exploration for core and fuel cycle strategies for the base line design, while the University of Cambridge will focus on alternative options with AGR-type fuel configurations. The industrial partner will lead the economic analysis effort and contribute to the development of refuelling and maintenance strategies as well as the safety analysis tasks.