In-situ deformation measurement of Zircaloy-4 cladding tube under various transient heating conditions using optical image analysis

Abstract

In a loss of coolant accident (LOCA), fuel cladding deformation is an important factor in terms of maintaining coolable geometry. In order to simulate the cladding deformation behavior, experimental research and the development of a fuel performance code have been conducted. In addition, relevant experimental data concerning the major phenomena for validating the developed code are required. Therefore, in this study, an experimental apparatus named ‘DIMAT’ (Deformation In-situ Measurement Apparatus by image-analysis Technique) is developed to produce high temperature cladding tube deformation data. In order to simulate various accident conditions, an infrared (IR) furnace and pressure injection equipment were assembled. Additionally, the cladding specimen in the IR furnace was clearly recorded by application of high temperature resistant black spray paint and modification of a quartz tube. Some uncertainty factors that might arise due to the paint application were considered and evaluated. After the deformation behavior in a scenario was recorded, the in-situ hoop strain of the cladding was calculated through the developed image analysis method. To ensure accuracy of the established image analysis system, a validation experiment and uncertainty evaluation were performed. Finally, the burst experiments were carried out at low and high heating rates of 1, 14, and 28 °C/s, and consequently the in-situ high temperature strain rate was successfully measured in each experimental case.