A significant milestone in the Megapie project, the world's first liquid-metal neutron spallation source, was reached when its containment structure was proof tested in a full-scale liquid-metal leak experiment. The experimental apparatus used in testing the effects of a liquid-metal leak of lead-bismuth eutectic on a heavy-water-cooled confinement at full scale is described. Measurements taken during the experiment validated the design chosen for the containment, a water-cooled aluminium double hull, and demonstrated that the experimental apparatus was capable of reproducing an accidental leak. The data acquired during this one-off experiment can be used in the future to assess liquid-metal leaks analytically.

In the event of a catastrophic failure in the spallation source, the experiment proved that the products of the ensuing liquid-metal leak would be safely contained and cooled. Furthermore, analytical methods used in predicting the outcome of a leak were validated. Indeed, transient fluid-dynamics, thermal and thermostructural calculations performed ahead of the test to predict temperatures and stresses in the aluminum containment and temperatures of the cooling loop agreed well with measurements.