3D Simulation On Transient Characteristics Of Fluid In The Cold And Hot Pools Of Pool-typed Sodium-cooled Fast Reactor Under Loss Of Steam Generator Feedwater Accident

The pool type sodium cooled fast reactor is one of the most important types of advanced nuclear reactor in the future.It is of great significance to study its safety under various accidents.However,it is very difficult to conduct sodium experiments in large-scale models,so numerical simulation has become a common safety analysis method.Different from other types,the fluid in hot and cold sodium pool of pool type sodium-cooled fast reactor has obvious three-dimensional characteristics,especially under various transient conditions,which will have a complex effect on the components in the reactor.But its internal complex structure makes it is hard to conduct 3D simulation,so most of the existing research used system simulation program or simplified 3d model to do transient calculations,which can’t accurately simulate the complex three dimensional phenomena in the pool.For this reason,taking China Experimental Fast Reactor(CEFR)as an example,a three-dimensional detailed full-size model of the sodium pool and its components was established,a decoupling modeling and coupling calculation scheme is used to solve the difficulty of meshing,and the thermal and hydraulic characteristics of the fluid in the pool are calculated.The temperature,pressure and velocity in the pool could be obtained,providing important input parameters for engineering,operation and mechanical evaluation.In this paper,a detailed full-size model of cold pool is established for the first time among the previous three-dimensional coupling calculations about pool typed fast reactor,which are mostly focused on the hot pool and simplified the cold pool a lot.And many phenomena not found in the existing three-dimensional calculations and one-dimensional or two-dimensional programs are observed,such as the special hot-cold-hot-cold temperature distribution in the vertical direction and the circumferential temperature difference due to baffles,which are of great significance to ensure the safe operation of CEFR.In addition,users-defined-function(UDF)in FLUENT is used to control the change of core power,IHX power and main pump flow rate during the long transient process.By changing the UDF program,various transient conditions can be calculated without changing the model and grid,which is not limited to the coolant loss accident in this paper.Therefore,the 3D model proposed in this paper is of great significance for studying the safe operation of CEFR under various working conditions.