Translated Abstract
The peak value of fuel pellet and cladding temperature is one of the important factors for the assembly design of liquid metal cooled fast reactor. Therefore, it’s necessary to predict the distribution of pellet temperature, cladding temperature and coolant temperature in the assembly, which is highly important for the economics and safety characteristics of core design. The sub-channel analysis will be the main research method for the core design of fast reactor and thermal-hydraulic investigation. Compared to the single channel model, the sub-channel model can give more accurate results. In present work, typical fuel assembly design of sodium cooled fast reactor is selected as the research target, and some mathematic model has been established in the sub-channel analysis code. The work of node division, code development and calculation has been carried out. The conduction model of mixed fuel UO2-PuO2 was adopted in the sub-channel analysis. The comparison of the flow velocity distribution in the fuel assembly was performed between CRT model and Novendstern model. Some different heat transfer correlations were compared with each other and one was selected as the optimization correlation. Based on the sub-channel code, the Chinese Experimental Fast Reactor(CEFR) was investigated. The thermal-hydraulic characteristics under different ratio of pitch to diameter(P/D) was investigated, the result was compared to that of THAS-PC2 code and other code such as MATRA-LMR, SLTHEN, Relap5-3D.Based on the study, some useful conclusion has been obtained. Compared to the single channel model, the sub-channel analysis considered the mass, energy and momentum exchange of coolant between the neighboring channels in the assembly. The mass, energy and momentum exchange could cause the mass flow rate was changing axially in each sub-channel, which made the enthalpy rise in hot channel was smaller and it is beneficial to the safety feature of fuel rod. The coolant temperature profile in different type sub-channel was slightly different. The coolant temperature changed with the radial position and the center channel achieve the largest coolant and cladding temperature, the lowest cladding and coolant temperature occurred in the angle channel. The temperature difference between cladding and coolant was small because of the excellent conduction capacity of sodium. Since the linear power flux of fast reactor was higher than that of PWR and the conduction capacity of fuel pellet in fast reactor was worse, the central temperature of fuel pellet was larger than that of PWR.
Translated Keyword
[Fast Reactor Subchannel Model Wire Liquid Metal]
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