The Mandrel Test for Controlled Displacement of Zircaloy Tubes

This report describes some initial work at IE to develop a displacement controlled test for testing the material properties of spent fuel cladding tubes. The objective is to have a test which allows stable failure under increasing and for which the level of axisymmtery can be controlled. The cone-Mandrel test consists of a set of arc-shaped segments placed inside a section of a Zircaloy tube and pushed outwards by the vertical displacement of a conical shaft. The cone-mandrel is first developed for unirradiated conditions but the test should also be applicable for irradiated components in hot cells at ITU. The report describes the practical implementation of the cone-mandrel with 8 segments and applied to three specimens. The tests show that the cone-mandrel can be used to attain controlled displacements until failure. The load is not accurately monitored for very low loads due to misalignment between cone, segments and tube. It is, however, straight-forward to compensate for this effect from the registered displacement/strain curve.