Final report for the perturbation experiment Mol-18/A2

The experimental series Mol-18 in the BR-2 reactor in Mol, Belgium, consisted of three single pin experiments, in which typical fast breeder fuel pins were investigated under mild overpower and mass flow accidental conditions. Mol-18/A1 used a fresh Mark-Ia pin for in-pile tests of the experimental loop, in Mol-18/B3 an irradiated Mark-II pin with 2.3 % burnup underwent a power transient and a combined power- and mass flow-perturbation, and the same type of tests were imposed in Mol-18A2 on a Mark-Ia pin, which had been irradiated in KNK-II up to a burnup of 4.8 %. The post experimental studies were complemented by extensive investigations on comparable fuel pins of the same fuel assembly, which had not been used for the transient tests. The present report gives an overview on the experimental history of the experiments, some calculational results and the conclusions to be drawn from the nondestructive and destructive post-experimental investigations