Preliminary Results of Gas Injection into Sodium Flowing in a 37-Pin Bundle

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Haga, K.*; Kikuchi, Y.*; Daigo, Y.*

Haga, K.*; Kikuchi, Y.*; Daigo, Y.*

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Out-of-pile experiments were conducted to evaluate the thermal and hydrodynamic effects due to gas injection into sodium flowing in a 37-pin bundle, which consisted of a central gas-injection pin, seven electrically heated pins and other dummy pins. Thermocouples were installed on the cladding of heated pins. The first series of experiments were carried out without gas injection to establish base cases and to evaluate the effect of mixing due to spacer wires. The experimental results agreed well with the predictions by the NORMAL code which considers the effect of mixing due to spacer wires. The second series of experiments were conducted with injecting argon gas transiently or continuously through a small nozzle (0.20.3 mm in diameter) of the gas-injection pin. In the transient injection experiment rapid temperature rises due to gas blanketing were observed on the surfaces of the heated pins at the axial position where gas was injected. In the continuous injection experiments, however, the measured wall temperature rises were small and well within tolerable limits.