Structural integrity analysis for exposure to elevated temperatures in the point lepreau irradiated fuel bay

In response to the March 11, 2011, Fukushima Daiichi accident, Point Lepreau Generating Station performed a structural integrity analysis of its irradiated fuel bay under elevated temperatures up to and including boiling. As a typical CANDU-6 in-ground fuel bay design, the objective of the analysis was to estimate by a detailed three-dimensional nonlinear finite element analysis the sustained concrete cracking and corresponding stress state due to a beyond design basis temperature increase. This was done to obtain a more reliable simulation of the reinforced concrete structural behaviour as well as information on the structural degradation under the imposed structural and thermal loading conditions if they occur during the temperature rise of interest. A second objective was to estimate the expected leakage rate from the fuel bay due to any through wall cracking identified in the analysis. In this paper, the finite element analysis methodology and its results are discussed.