[en] A fuel oxidation and diffusion-based fission product release model has been developed from the recent analysis of ¹³⁴Cs data from a number of experiments performed at the Chalk River Laboratories (CRL). The release model was based on data from six tests in the Hot Cell Experiment (HCE2). These tests were conducted in steam from 1354 to 1651 degrees C, and contained fuel samples of either bare fuel fragments or Zircaloy-clad mini-elements. The fraction of fission products trapped in the fuel was also determined from additional tests in the Hot Cell Experiments (HCE1 and HCE2), and the Universal Cell Experiment (UCE12). The model has been validated against eight other tests not used in the model development, resulting in a value of 0.11 for the mean absolute difference from experiment. The present treatment has also been compared to the ORNL simple diffusion model and the empirically based CORSOR-M model with resultant mean absolute difference values of 0.24 and 0.17, respectively, for the same validation set. (author)