Heat exchanger

The heat exchanger described is of the single pass straight tube type and the purpose of the invention is to limit the thermal stresses which tend to damage the very thick end plates of the steam generators of a PWR type reactor. These stresses are caused by relatively cold feed water coming into contact with the end plate's inner surface, while the outer surface is in contact with hot coolant. The situation is worsened by the inclusion of baffle plates forming an economiser section. The invention involves the establishment of a high temperature buffer volume between the economiser section and the end plate, into which feed water leaks through the annular spacesin the tube holes of the economiser end plate, and from which steam generated may be bled off. In addition a shroud, attached to the economiser end plate, encloses the tube bank, leaving a narrow annular space between it and the heat exchanger vessel. (JIW)