Background: Reactor safety is an important component of developing and designing any nuclear energy systems.The Freeze-Valve is one of the core technologies of the molten salt reactor

which thermal-structural property is directly related to the inherent safety of the molten salt reactor nuclear system.Purpose: The purpose of this paper is to improve the inherent safety of the fourth-generation nuclear energy systems

by researching and optimizing the thermodynamic properties of Freeze-Valve

and exploring reliable safety design.Methods: A 3D Finite Element model to simulate the thermal-structural coupling behaviors was established by the ANSYS software to analyze the performances and the properties of a Freeze-Valve.Results: The analysis result shows that the flat part of the Freeze-Valve plays a very important role in engineering applications.The effects of different factors（heat transfer coefficient

heating power

and insulation size and so on） on the temperature and the stress field of the Freeze-Valve during operation are obtained

which provide some basis for optimization of design and safe operation.The thermal stress of the initial model of the Freeze-Valve is so large that it is easy to cause fatigue failure

owing to the unreasonable initial design（insulation size and heating power

for example）.Conclusions: After the relative analysis and structural optimization

the maximum stress of the Freeze-Valve is significantly reduced

and the performance has been greatly improved.