Evaluation of Fracture Resistance Behavior of Zircaloy Fuel Clad Tubes of Indian PHWRs Using Experiments on Ring Specimens and Continuum Damage Mechanics Models

摘要

Continuum damage mechanics models are very popular in prediction of crack growth and fracture resistance behavior of low-alloy ferritic and austenitic stainless steel components of nuclear reactors with various postulated flaws under different loading conditions. However, literature regarding the application of the above models for prediction of fracture behavior of Zirconium alloys, which are used for manufacture of fuel-clad and pressure tubes etc., are very limited. These models are very useful for designers and safety analysts as the parameters of the models are truly material properties and are transferable from the specimen to the component level. In this work, the nonlocal version of the Rousselier's damage model was used to predict the fracture resistance behavior of double-edged-notched-tensile specimens made from Zircaloy-4 material. Initially, the micro-mechanical parameters were determined from the testing of ring-type specimens. Subsequently, these parameters were used in finite element analysis of the double-edged-notched-tensile specimen in order to predict the crack growth behavior and the crack path under applied displacement-controlled loading conditions. The fracture resistance behavior obtained in terms of J-R curve was also compared with the corresponding J-R curves of an axially-cracked pin-loading-tension specimen. The results were also compared with similar data from literature wherever possible. From the above results, it can be concluded that the nonlocal Rousselier's damage model is a suitable tool for prediction of accurate fracture resistance behavior of various Zirconium alloy components in the nuclear reactors in order to ensure structural integrity of the above components in various postulated accidental scenarios.