Likelihood and Consequences of Fuel String Compression at Point Lepreau Generating Station

Abstract

During an accident which results in fuel heatup, axial thermal expansion of the fuel string relative to the pressure tube will occur. If the temperature transient is sufficiently severe, the fuel string may contact the shield plugs at both ends of the channel. Any additional axial thermal expansion will result in deformation of fuel and fuel channel components, leading to tensile or compressive stresses in the different fuel channel components. If these loads become sufficiently large, they could result in failure of a fuel channel component or to channel failure due to bending of a fuel element under load The analysis described in this paper demonstrates that this process would not result in fuel channel failure for a design basis accident at Point Lepreau Generating Station (PLGS), even if the station were retubed to "as-built" channel lengths.