Sag of Zr-2.5% Nb Pressure Tubes

Abstract

This paper presents a comparison of predictions of pressure tube sag and pressure tube/calandria tube (PT/CT) contact with measurements in power reactors. The absolute sag deflection and the rate of deflection in the channels studied in Pickering Unit 3 and Bruce Unit 2 are predicted equally well by both PT design equations currently in use. However, in-reactor sag deflection data cannot be used to test the validity of PT deformation models. PT/CT contact data do provide such a test. The more recently developed PT design equation is in better agreement, on average, with the small available set of contact data from power reactors, and is likely to give a better estimate of the closest possible approach of contact toward the channel outlet.