Development a methodology for evaluating inter‐assembly heat transfer effect through reactor core in system safety analysis of sodium‐cooled fast reactor. (20th January 2021)

• Record Type: Journal Article
• Authors: Wang, Shibao; Zhang, Dalin; Liang, Yu; Wang, Xinan; Qiu, Suizheng; Su, Guanghui; Tian, Wenxi
• Other Names: Şahin Sümer guestEditor.
• Is Part Of: International journal of energy research. Volume 45:Number 8(2021)
• Page Start: 12258
• Page End: 12271
• Publication Date: 2021-01-20
• Subjects: inter‐assembly heat transfer effect -- sodium‐cooled fast reactor -- system analysis -- whole flow regimes; Power resources -- Periodicals; Power (Mechanics) -- Periodicals; Power resources -- Research -- Periodicals; 621.042
• DOI: 10.1002/er.6369
• Languages: English
• ISSNs: 0363-907X

Abstract

Summary: Closed type assembly leads to complicated core thermohydraulics which are significant for design and safety analysis in sodium‐cooled fast reactor (SFR). Most of the major phenomena can be dealt with by general parallel channel network and two‐dimensional model for inter‐wrapper flow (IWF) in system code transient thermal‐hydraulic code for analysis of SFR (THACS). A main deficiency left is the overestimation of inter‐assembly heat transfer effect due to lump temperature message that one‐dimensional assembly model can only provide. A methodology was thus developed to compute wall‐subchannel temperature for simulating energy transportation through duct wall. Intra‐assembly thermohydraulics were classified as two mechanisms and non‐dimensional parameter was introduced for characterizing each of them. Ratio between linear heat flux density through hexagonal wrapper surface and pin surface q w / p was employed to account for radial heat transfer. Flow redistribution effect arouse in mixed and natural convection was concretized by a importance symbol of buoyancy force, Richardson number Ri. Two criteria were also proposed for dividing flow state into three parts and specific model for each section was defined. Two validation cases against 3‐D computational fluid dynamics (CFD) simulation of China experimental fast reactor whole core and test data from plant dynamics test loop with direct heat exchanger experiment were performed with THACS. Noticeable improvement after incorporation of this model demonstrated its value in system analysis. Although the procedure for parameter computations is geometry related, this method can be reproduced to any type of assembly directly. Abstract : A methodology for improving prediction of inter‐assembly heat transfer effect in sodium‐cooled fast reactor when performing efficient system analysis was developed; two non‐dimensional parameters were introduced to characterize intra‐assembly radial heat transfer effect and flow redistribution phenomenon, respectively, and two criteria were also proposed for dividing whole flow state into three parts where specific model for each section was defined and two validation cases against 3‐D CFD simulation of CEFR whole core and test data from PLANt dynamic test loop (PLANDTL) experiment were performed with THACS and noticeable improvement was achieved with this method. Fig 1 Characteristic thermal‐hydraulic phenomena in sodium‐cooled faster reactor Fig 2 Comparison of local temperature levels between test and two simulation cases