Experimental and numerical investigation of temperature stratification phenomena during heating-up processes of fluids in passive cooling systems


Experimental and numerical investigation of temperature stratification phenomena during heating-up processes of fluids in passive cooling systems

Krepper, E.; Beyer, M.

In modern designs of nuclear reactors often natural circulation is used as a passive mechanism for heat removal. In the concepts the heat is removed from the reactor and transported into a large pool. Examples are the pressure suppression pool (wet-well) of the ESBWR, the in-containment refuelling water storage tank of the AP-1000, the pool of the emergency condenser of the SWR-1000 and the gravity driven water pool of the AHWR.
In large pools temperature stratification can compromise the heat transfer process. Generation of steam might lead to an increase of the flow velocities, to a mixing of liquids having different temperatures and to a disappearance of temperature stratification. At the corresponding temperatures steam is released from the pool into the containment and influences the increase of the containment pressure. Under conditions of strong temperature stratification compared to a homogeneous temperature distribution, the fluid at the top of the pool much earlier reaches the saturation temperature. The evaporation starts much earlier resulting in an earlier the pressure increase in the containment.
In the presentation both experiments and numerical CFD simulations are reported to investigate the capability of actual CFD modeling this task.

Keywords: passive safety systems; large pools; natural circulation; experiments; CFD

  • Lecture (Conference)
    Multiphase Flow: Simulation, Experiment and Application, 24.-26.06.08, Dresden, Germany

Permalink: https://www.hzdr.de/publications/Publ-11578
Publ.-Id: 11578