ESTIMATION OF LEAK TIGHTNESS IN THE ROLLED JOINED PRESSURE TUBE–END FITTING ASSEMBLY USED IN PHWR

Abstract

This report attempts to review the joint technology utilized in the nuclear industry. As we all know that PHWR is the pressurized heavy water reactor used in the nuclear industry. In pressurized heavy water reactors (PHWR), pressure tube to end fitting rolled joint is critical for safe operation. The joint requires sufficient contact pressure for leak tightness and lower undesirable residual stress within the transition region of the tube. This work aims to assess various roller paths for roll expansion of the line to reduce residual tensile stress while maintaining the specified leak tightness. Consequently three-dimensional, explicit finite element simulations, of the roll expansion process are disbursed. Several roller paths are considered within the simulation to vary the strain path of deformation. When we increase the number of rotations of the roller, the residual stresses decrease. In addition to that, the contact pressure is found to be within the acceptable range for leak tightness. But, beyond a specified number of rotations, the stresses are found to saturate, hence putting an upper bound on their number.