Heat and Mass Transfer

, Volume 53, Issue 2, pp 537–551 | Cite as

Natural and mixed convection in the cylindrical pool of TRIGA reactor

  • R. Henry
  • I. Tiselj
  • M. Matkovič


Temperature fields within the pool of the JSI TRIGA MARK II nuclear research reactor were measured to collect data for validation of the thermal hydraulics computational model of the reactor tank. In this context temperature of the coolant was measured simultaneously at sixty different positions within the pool during steady state operation and two transients. The obtained data revealed local peculiarities of the cooling water dynamics inside the pool and were used to estimate the coolant bulk velocity above the reactor core. Mixed natural and forced convection in the pool were simulated with a Computational Fluid Dynamics code. A relatively simple CFD model based on Unsteady RANS turbulence model was found to be sufficient for accurate prediction of the temperature fields in the pool during the reactor operation. Our results show that the simple geometry of the TRIGA pool reactor makes it a suitable candidate for a simple natural circulation benchmark in cylindrical geometry.


Computational Fluid Dynamic Natural Convection Computational Fluid Dynamic Simulation Computational Fluid Dynamic Model Reactor Core 
These keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.

List of symbols


Thermal diffusivity (m2 s−1)


Coefficient of thermal expansion (K−1)


Turbulent dissipation (J kg−1 s−1)


Thermal conductivity (W m−1 K−1)


Density (kg m−3)


Time constant of the thermocouple (s)


Kinematic viscosity (m2 s−1)


Error (δx—error in x coordinate)


Change, difference (Δt—change in time t)


Specific heat capacity (J kg−1 K−1)


Diameter of the thermocouple (m)


Gravity acceleration (m s−2)


Heat transfer coefficient (W m−2 K−1)


Turbulent kinetic energy (J)


Fuel element half-length (m)


Mass (kg)


Mass flow rate (kg s−1)


Heat flux (W m−2)


Time (s)


Velocity (m/s)

x, y, z

Cartesian coordinate components (m)


i-th spatial coordinate (m)


Heat capacity of the pool (J K−1)


Characteristic length (m)


Rayleigh number


Surface of the thermocouple (m2)


Temperature (°C)


Temperature measured by the thermocouple (°C)


Volume of the pool (m3)


Volumetric flow rate (m3 s−1)



The authors gratefully acknowledge the valuable contributions of the reactor operator staff at JSI, in particular from Anže Jazbec, Darko Kavšek, Sebastjan Rupnik and Marko Rosman, for their help from the conception to the realization of the experiment. Research was founded by P2-0026 research program Nuclear engineering.


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Copyright information

© Springer-Verlag Berlin Heidelberg 2016

Authors and Affiliations

  1. 1.Reactor Engineering Division R4Jožef Stefan InstituteLjubljanaSlovenia

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