HLM fuel pin bundle experiments in the CIRCE pool facility

Results reported in the present work, represent the first set of experimental data concerning fuel pin bundle behaviour in a heavy liquid metal pool, both in forced and natural circulation. A full characterization of the FPS has been experimentally achieved for Peclet numbers in the range of about 500-3000. Obtained experimental data point out a linear trend of Nusselt number as a function of Peclet in agreement with Mikityuk and Ushakov correlations showing a general tendency to underestimate them; in particular, the newly experimental data points are about 25% lower than Nu derived from correlations available in the literature.