Numerical study of defect in end plug weld joint of FBTR fuel pin

The fuel pins of fast reactor encounter high pressure, high temperature, high neutron fluence and sodium environment in their life time. This demands for high level of end plug weld integrity and hence, the acceptance criteria for these welds are very stringent. The defects usually encountered in the weld joints are micro-cracks, porosity, lack of fusion, root-pocket, etc. Amongst these weld defects, root-pocket at the weld joint is the most prominent defect observed in FBTR fuel fabrication campaign. The present paper deals with the FEM analysis of the weld zone having different sizes of root-pockets for the pressure developed inside the pin due to fission gas release and creep damage due to higher operating temperature.