High - Temperature Bundle Deformation Experiments Under Conditions Applicable to LBLOCA With ECI Available

Abstract

A high temperature bundle deformation experiment was performed in Stern Laboratories to investigate the bundle behavior under conditions applicable to LBLOCA with ECI available. A bundle comprised of seven CANDU fuel elements was used in the experiment. A self-contained test loop was constructed to perform the simulations under pressures up to 2 MPa in saturated steam environment. The bundle was heated by directly passing electrical current through it and real-time planar element deflections were measured using two Linear Variable Displacement Transducers at each point of interest. Four different tests were performed, each one using a unique power profile. The peak power values were gradually increasing to account for conditions applicable to AOO, and eventually LBLOCA. At the LBLOCA nominal condition, a maximum power value of 64 kW was applied, which caused maximum and local heat-up rates around 64 and 56 °C/s, respectively, a local sheath peak temperature of 950 °C, and a high-temperature (>800 °C) duration above 30 seconds. The transient displacement profiles indicate a sag-type deformation with a magnitude of ~1 mm at midspan between the bearing pad planes. The post-test inspection revealed that the bundle remained intact and that the elements exhibited a sag-type deformation consistent with the transient deflection data. The temperature-deflection correlations and analyses were obtained from the test data.