Three-dimensional numerical research on natural circulation characteristics of decay heat removal system in pool-type fast reactor CEFR

• Published in: Nuclear engineering and design 2021-11, Vol.383, p.111424, Article 111424
• Main Authors: Liang, Jiangtao, Lu, Daogang, Fu, Jingpin, Zhao, Haiqi, Luo, Xinyue, Zhang, Yuhao
• Format: Article
• Language: English
• Subjects: Blackout; CEFR; Cooling systems; Decay; Decay rate; DHRS; Flow paths; Flow rates; Flow velocity; Heat; Mathematical models; Natural circulation flow paths; Nuclear safety; Primary circuits; Reactors; Safety systems; Simulation; Sodium; Sodium cooled reactors; Subassemblies; The primary circuit system; Thermal stratification; Three dimensional flow; Three dimensional models; Three-dimensional numerical simulation
• ISSN: 0029-5493; 1872-759X
• DOI: 10.1016/j.nucengdes.2021.111424

•CEFR DHRS primary system with full core CFD model is established.•The intra-subassembly flow path, inter-wrapper flow path and MVCS backflow path are identified.•The three-dimensional thermal and flow characteristics in sodium pool are analyzed. The pool-type sodium-cooled fast reactor decay heat removal system (DHRS) is an important engineered safety system to ensure the establishment of natural circulation in the case of station blackout (SBO). It is of great significance to study characteristics of DHRS for evaluating its passive residual heat removal capacity. Due to numerous core subassemblies and small scale of gaps between subassemblies, it is difficult to use the same scale grids to describe the three-dimensional flow paths in sodium pool with full core. Therefore few researches, either experiments or numerical simulation, have been performed on such complicated phenomena so far. In order to identify the natural circulation flow paths of fast reactor, an integrated three-dimensional simulation model of China Experimental Fast Reactor (CEFR) primary circuit system with full core was established, including 712 subassemblies and small gaps between subassemblies. FLUENT was used to carry out three-dimensional numerical simulation. Through the transient simulation of 5000 s, the main flow paths including the intra-subassembly flow path, the inter-wrapper flow path and the Main Vessel Cooling System (MVCS) backflow path were identified. At 5000 s, the intra-subassembly flow rate, the inter-wrapper flow rate, and the MVCS backflow rate were 3.07 kg/s, 1.53 kg/s, and −1.94 kg/s respectively. Thesymmetrical thermo-hydraulic characteristics of two loops were obtained to analyze thermal stratification in sodium pool. The results provided a key three-dimensional numerical reference for the safety of CEFR.