The KASOLA (KArlsruhe SOdium LAboratory) at INR is a versatile experimental facility to investigate flow phenomena in liquid sodium for solar and nuclear fusion applications. The facility was constructed in a cylindrical steel building with an inner diameter of 7.7 m and a usable height of 12.5 m. It hosts a sodium inventory of 7 m³, and it can operate in the range of about 150–550 °C. A magneto-hydrodynamic (MHD) pump provides a maximum flow rate of 150 m³/h at a pressure head of 0.4 MPa.


Fig. 1. Inner view of the KASOLA facility and one of its test section


The facility offers three experimental ports for liquid metal experimental investigations of various types.

1 ) The primary test section is nearly 6 m and can be used for developments and investigations of targets, component tests and experiments with high mass flow rates.

2) The second test port connects a direct thermal storage device, which is foreseen to test the dynamic capabilities of a frozen thermocline storage tank (FlexStor).

3) At the low temperature port separate experimental loops or devices, which can use the calibration and cleaning units of KASOLA can be connected.


A key feature of the KASOLA facility is its flexibility, enabling the conduction of a wide spectrum of thermal-hydraulic experiments for solar and nuclear applications:

  • Qualification, validation and improvement of turbulent liquid metal heat transfer models in CFD (Computational fluid dynamics) as well as reduced order models
  • Development of free surface liquid metal targets for accelerator applications
  • Development of models to describe free surface liquid metal flow
  • Investigation of transition in convective flow patterns between forced, mixed and free convection modes
  • Thermal-hydraulic investigations of flow patterns in fuel bundles or pool configurations at prototypical or scaled heights
  • Qualification of components and instrumentation or measurement devices for sodium running applications in CSP (Concentrating Solar Power)


The KASOLA facility contributes to the Helmholtz alliance on liquid metal technology (LIMTECH) and the Helmholtz Energy Materials Characterization Platform (HEMCP). LIMTECH was established to support the German Helmholtz centers and universities to bundle their R&D activities on liquid metals for various research fields and applications. HEMCP was founded to respond to the needs of innovative energy systems, which will face much higher temperatures to enhance their efficiency.



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  • W. Hering, M. Böttcher, J. Fuchs, A. Onea, S. Ulrich, R. Stieglitz, Materials and systems for liquid metal based CSP 2.0, AIP Conf. Proc. 2303, 050002, 2020
  • W. Hering, A. Onea, A. Jianu, J. Fuchs, Th. Schaub, A. Weisenburger, S. Ulrich, R. Stieglitz, Facilities to investigate sodium and materials behaviour up to sodium boiling, Proc. ICAPP 2020, paper 20205, March 15-19, 2020, Abu Dhabi, UAE
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  • A. Onea, W. Hering, M. Lux, R. Stieglitz, Numerical optimization of cold trap designs for the Karlsruhe Sodium Laboratory, Int. J. Heat Mass Transfer 113, 984 - 999, 2017
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