Title: Development of the Mandrel Test for Controlled Displacement of Zircaloy Tubes : Summary of Initial Work 2007
Authors: NILSSON KARL-FREDRIKCHENEL RAMOS RAFAELVOKAL VRATKOMENDES JOSEMARTIN OLIVER
Publisher: OPOCE
Publication Year: 2008
JRC N°: JRC43877
ISSN: 1018-5593
Other Identifiers: EUR 23283 EN
URI: http://publications.jrc.ec.europa.eu/repository/handle/JRC43877
Type: EUR - Scientific and Technical Research Reports
Abstract: 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 stavle 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 un-irradiated 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. The tested specimens were subsequently analysed by fractographic studies. The main fracture was by shearing along lines that make 45¿ angle with the axial and circumferential directions. The tests were simulated by non-linear finite element (FE) calculations. The finite element calculations simulated the experimental observations quite well. The FE calculations also allowed us to better understand the failure by necking and the deviation of axi-symmetric loading due to stress concentrations at the end of the segments. Furthermore the cone is also subjected to plastic deformation. The plastic deformation of the cone and the deviation from axi-symmetric load conditions can be reduced by increasing the number of segments. To this end mandrels with 6, 8 and 10 segments were analysed. The conclusion is that one should use at least 8 segments and that one should use a harder material for the cone.
JRC Directorate:Energy, Transport and Climate

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