BR2 bundle mockup heat transfer experiments

Abstract Heat transfer calibration tests on helium cooled bundles of 12 artificially roughened rods have been performed, with the purpose of obtaining information for the thermo-hydraulic design of the 12-rod bundle fuel element to be irradiated in BR2. The rods were electrically heated. Altogether 50 isothermal and 110 non-isothermal runs were performed. The maximum achieved rod linear power was 460 W/cm, the maximum measured wall temperature was 790°C. The code SAGAPO was developed to predict the thermohydraulic performance of such clusters. This paper describes the measurements performed, the experimental set-up and the fundamentals of the SAGAPO code. The main results of the calculations performed with SAGAPO for the BR2 irradiation experiment are also given.