Salt-cooled High-temperature Reactors

点击翻译按钮获取中文摘要

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.