The burnt fuel assemblies, which are unloaded from the reactor core, are storage in a water-cooled storage pool until radioactivity and heat decays to the authorized transportation value of dry storage containers.

With the incident in a storage pool fatal consequences can occur that depend on the initiating event (station blackout, loss of coolant, etc.). The integrity of the cladding tubes of the fuel assemblies is an important aspect in the nuclear safety.

Thermal-hydraulic phenomena were investigated, which occur during evaporation of the storage pool and overheating of the steam followed by an upwards flow in the fuel assembly boxes. According the principle of similarity, physical parameters of the steam upwards flow were simulated by not heated model gases.

The overflow of air above the fuel assembly storage boxes was experimentally investigated in a horizontal overflow channel. The conditions of the air overflow were vary by air conditioning (temperature, humidity). The interactions of density driven flow or diffusion (air / gas model) and the interaction (air / steam) with the overflow simulated the thermal-hydraulic phenomena during these processes.

The paper includes the presentation of the experimental facility and some results of the experiments.

This research project supported by the German Federal Ministry of Education and Research named SINABEL (Safety of spent fuel pools: Experimental analysis, modeling and validation of system and CFD codes) delivers with a combination of experiments and simulations, knowledge’s of the heat transfer processes for the case of a partially or completely evaporated spent fuel storage pool in light water reactor nuclear power plants both within the fuel rod bundle of a fuel assembly (FA) and in the spaces between the FA in order to be able to predict via the modeling and simulation the development of the axial and radial temperature profiles of rods by different accident scenarios.

SINABEL is a joint research project which three research institutions (TU-Dresden, HZDR and HSZG) work together.

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