Journal of computational fluids engineering (한국전산유체공학회지)

Korean Society of Computational Fluids Engineering (한국전산유체공학회)
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COMPUTATIONAL FLUID DYNAMICS ANALYSIS OF THERMAL STRATIFICATION IN THE UPPER PLENUM OF THE MONJU FAST BREEDER REACTOR

몬주 고속증식로 상부플레넘에서의 열성층에 관한 전산유체역학 해석

  • Choi, S.K. (Fast Reactor Design Division, Korea Atomic Energy Research Institute) ;
  • Lee, T.H. (Fast Reactor Design Division, Korea Atomic Energy Research Institute)
  • 최석기 (한국원자력연구원 고속로설계부) ;
  • 이태호 (한국원자력연구원 고속로설계부)
  • Received : 2012.10.15
  • Accepted : 2012.12.22
  • Published : 2012.12.31
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Abstract

A numerical analysis of thermal stratification in the upper plenum of the MONJU fast breeder reactor was performed. Calculations were performed for a 1/6 simplified model of the MONJU reactor using the commercial code, CFX-13. To better resolve the geometrically complex upper core structure of the MONJU reactor, the porous media approach was adopted for the simulation. First, a steady state solution was obtained and the transient solutions were then obtained for the turbine trip test conducted in December 1995. The time dependent inlet conditions for the mass flow rate and temperature were provided by JAEA. Good agreement with the experimental data was observed for steady state solution. The numerical solution of the transient analysis shows the formation of thermal stratification within the upper plenum of the reactor vessel during the turbine trip test. The temporal variations of temperature were predicted accurately by the present method in the initial rapid coastdown period (~300 seconds). However, transient numerical solutions show a faster thermal mixing than that observed in the experiment after the initial coastdown period. A nearly homogenization of the temperature field in the upper plenum is predicted after about 900 seconds, which is a much shorter-term thermal stratification than the experimental data indicates. This discrepancy is due to the shortcoming of the turbulence models available in the CFX-13 code for a natural convection flow with thermal stratification.

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References

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