Investigation on leakage and solidification characteristics of fluorides in molten salt reactor

Abstract

BackgroundThe high temperature molten salt is generally used as the heat transfer medium in molten salt reactor (MSR), and the molten salt leakage accident is a crucial issue for the safety of reactor operation.PurposeThis study aims to investigate the characteristics of molten salt leakage and solidification and to provide effective measures to reduce the risk of molten salt leakage accidents.MethodsBased on the computational fluid dynamics (CFD) model, the leakage of molten fluoride salt flow onto the quartz sand and subsequently phenomena including permeation, spreading, melting and solidification were studied by using ANSYS FLUENT code.ResultsThe results show that the molten salt diffuses both vertically and horizontally after contacting the sand, due to the cooling of ambient and temperature gradient of the sand, the bottom of molten salt in the sand will freeze, making the vertical permeation depth stabilized and the liquid molten salt will only spread horizontally on the top surface of sand. For a certain period of molten salt leakage, the higher the molten salt temperature and leakage flow rate, the larger the maximum diffusion radius of horizontal detection and permeation depth in vertical direction.ConclusionsBased on above analysis, a method with respect to the collection and thermal insulation of high temperature molten salt under leakage accident is proposed, and analyzed to verify the effectiveness of the method.

Keywords

• molten salt reactor
• fluorides
• leakage
• solidification