Effect of crossflow on flow distribution in HTGR core column.

Abstract

In the thermal hydraulic design of the high temperature gas-cooled reactor core consisting of prismatic fuel elements, the regulation of the coolant leakage flows is very important because these flows decrease the effective flow rate in coolant channels and are considered to be associated with the cause of the column fluctuation phenomenon. An analysis of the coolant flow distribution in the core is carried out by a one-dimensional flow network model. Since it is difficult to model leakage flow paths theoretically, the modelling of the flow network should be based on experiments. In this paper, the air flow test in a full-scale core column with one crossflow gap was carried out to study the effect of the leakage flows on the main coolant channel flows. The numerical results based on the flow network model agreed with the experimental data. Also, it is found that the effect of the leakage flow was large especially in the column with orifices.