CIRCUIT AND CONTAINMENT ASPECTS OF PHÉBUS EXPERIMENTS FPT0 AND FPT1

The Phebus FP severe accident experiments FPT0 and FPT1 were performed at Institut de radioprotection et de sûreté nucléaire (IRSN, Radioprotection and Nuclear Safety Institute) Cadarache (France) in 1993 and 1996 respectively. In each test a 1 m long bundle of fuel rods plus a silver indium cadmium control rod was heated to an advanced state of degradation in the Phebus reactor, and the materials released were swept by an injected steam flow through a model circuit and into a miniature containment vessel. Test FPT0 used fresh fuel, while in FPT1 the fuel had a burnup of 23 GWd/tonne. In an international effort coordinated by the European Commission Joint Research Centre and IRSN intensive analytical study of data from the circuit and containment was performed using a variety of models and computer codes, seeking to reconcile the wide variety and copious quantity of online and post-test data available and to draw conclusions. The present consolidation report makes a critical survey of the degree of success achieved and draws conclusions as to where understanding can be considered good and where it appears necessary to perform further analytical work, factoring in both findings from other tests of the Phebus FP series and from other experimental programmes.JRC.F.5-Nuclear Reactor Safety Assessmen