Bruce NGS-B U-Bend Support Stabilization

Abstract

The steam generators at Bruce NGS B have experienced a degree of tube fretting at the U-bend scalloped bar support locations. Investigation attributed the tube fretting to flow induced vibration induced wear as a result of U-bend supports which were too widely spaced (compared to current criteria) and insufficiently rigid. The paper describes the problem, the development of a stabilization configuration, its qualification, its installation tooling and procedures and the installation of the initial trial assemblies.