HLMC Fuel Pin Bundle characterization in CIRCE-ICE pool facility

Abstract. This work, carried out at the DICI of Pisa University, in collaboration with ENEA Brasimone R.C., deals with the analysis and a preliminary discussion of the experimental tests performed in the Integral Circulation Experiment (ICE) configuration of the Circulation Eutectic (CIRCE) facility aiming to investigate the heat transfer in fuel rod bundle. The facility test section basically consists of an electrical bundle (FPS) made up of 37 pins arranged in a hexagonal wrapped lattice with a pitch to diameter ratio of 1.8. Along the FPS active length, two sections were instrumented to monitor the heat transfer coefficient along the bundle as well as the cladding temperatures at different ranks of the sub-channels. In particular, forced circulation condition tests were performed imposing a temperature difference through the FPS and a LBE mass flow rate through the FPS. Nusselt number in the sub-channels was calculated as function of the Peclet number and obtained results were compared to Nusselt numbers computed from correlations available in Heavy Liquid Metals (HLM) literature. Results shown that the Nu is slightly lower in the middle section (section 1) if compared with the ones into the upper section (section 3), and that behaviour is probably due to the turbulence of the flow which seems to be fully developed only in the upper part of the fuel pin bundle. Anyway the Nu number, calculated as function of the Pe number in the range Pe~1500÷3000 (forced circulation condition), matches well the numerical correlation available for HLM fuel pin bundle, (i.e. Ushakov and Mikityuk)