The characteristics of the coolant in the upper plenum of Liquid Metal cooled Fast Breeder Reactor (LMFBR) are experimentally examined in order to evaluate turbulent scales associated with thermal striping properties of the internal structure materials. The flow field was reproduced in a 1/20 scale reactor vessel with water as the simulant fluid, and the Upper Core Structure (UCS) was installed in the vessel. The results indicate that temperature fluctuation on the material becomes most vigorous at the separation edge of UCS and the turbulent characteristics of main flow could be classified before and after the impingement on UCS. The higher temperature flow hardly mixed with lower temperature surroundings up to the bottom of UCS, while a sufficient turbulent mixing was realized soon after the separation at the edge of UCS bottom. Temperature gradients were well correlated to the turbulent heat fluxes. It was pointed out that the gradient diffusion model could be applied for the flow fields with recirculating regions in this study.
|Number of pages||6|
|Publication status||Published - 1987|
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