Design and manufacturing of the IRIS helical coil steam generators

IRIS (International Reactor Innovative and Secure) is a light water cooled, 335 MWe power reactor which is being designed by an international consortium led by Westinghouse Electric Company.[1-2] IRIS features an integral reactor vessel that contains all the main primary system components including the reactor core, the coolant pumps, the steam generators, the pressurizer and the control rod drive mechanisms. This integral design approach eliminates the large coolant loop piping, and thus eliminates large loss-of coolant accidents (LOCAs) as well as the individual component pressure vessels and supports. The design and fabrication of the steam generators, which are internally contained within the reactor vessel, is a major effort in the development of the integral IRIS concept. Ansaldo-Camozzi ESC has a large experience in design and manufacturing of traditional steam generators, (see Figure 1) with 4 replacement steam generators (RSG) for Palo Verde Nuclear Power Plant Unit 1 and 3 being completed, while 2 RSG for Unit 2 are already installed and working. Based on this experience, Ansaldo-Camozzi ESC is the IRIS consortium member in charge for the IRIS Steam Generators development and manufacturing. This paper provides an overview of the current activities in this area, both from the point of view of design and manufacturing aspects, and illustrates the evolution from the early preliminary design to the current configuration. (authors)