Study on mixing due to transversal flow in a fuel subassembly of fast reactor; Sodium experiment using a 37-pin subassembly model

Kamide, Hideki ; Miyakoshi, Hiroyuki; Kawamata, Nobuhiro; Ohshima, Hiroyuki

High burnup core is one of significant ways to increase cost performance of a fuel cycle. Deformation of a pin bundle or wrapper tube due to irradiation has been studied for the high burnup core. Here, mixing phenomena with cross flow was investigated for a prediction method of thermohydraulics in a deformed pin bundle in a fast reactor. Sodium experiments were carried out using a wire wrapped 37-pin subassembly model, where a blockage was installed in order to make cross flow around it. The subchannel analysis code, ASFRE, was applied to the experimental analyses. Axial and transverse temperature distributions in the subassembly were correlated with the cross flow and the wire spacer. The calculated temperature profiles including a decrease due to the cross flow were in good agreement with the experimental results. ASFRE simulated also influence of the wire spacer. Database for mixing phenomena with the cross flow was obtained for a subassembly of fast reactor