Leak testing nuclear fuel elements

A production line for the manufacture of nuclear fuel elements includes a section for the on-line testing of the end cap welds of the fuel elements by enclosing the ends only in sealed chambers rather than the entire fuel element. Two testing heads are located one on each side of the path of travel of the fuel elements which are transported transversely of the lengths. Each element is loaded on to support rollers and testing heads are advanced towards one another to engage respective welded ends of the element and sealingly enclose the welded portions within chambers and a mass spectrometer testing cycle is initiated which involves evacuation of the chambers and monitoring for coarse and fine leakage of gas (typically helium) from the elements. The side wall of the cans are engaged by sealing rings in each testing head which are axially compressed to cause their internal diameters to be reduced to seal to the side wall. (author)