Stress relieving attachment of tube to tubesheet, such as in a pressure vessel shell of a nuclear reactor power system

Abstract

Steam generator systems including tubesheet assemblies, such as for use in nuclear reactor systems, and associated devices and methods are described herein. A representative steam generator system can be installed in a nuclear reactor vessel positioned to house a primary coolant. The steam generator system can include a tubesheet assembly defining a plenum and comprising a tubesheet and a flexible connection portion coupling the tubesheet to the reactor vessel. The tubesheet can include a plurality of perforations fluidly coupled to the plenum. The steam generator system can further comprise a plurality of heat transfer tubes fluidly coupled to the perforations and configured to receive a flow of a secondary coolant. The connection portion can be more flexible than the tubesheet and the reactor vessel to reduce stresses on the tubesheet and the connections (e.g., tube-to-tubesheet (TTS) welds) between the tubes and the tubesheet during operation of the nuclear reactor system.