The IRIS reactor design - An international co-operative project and the Brazilian participation

IRIS, the International Reactor Innovative and Secure, is an Integrated Primary System Reactor (IPSR) with innovative features that can meet most of the requirements for the next generation of nuclear energy systems. The IRIS project is being conducted as an international development program in a collaborative approach and management openness. This initiative has found a very positive response around the world and the IRIS team grew from the initial four members from two countries to the present number of 22 organizations from nine countries. By the end of 2001, the Brazilian Nuclear Commission, CNEN, signed a collective agreement with Westinghouse Electric Company to officially participate in the development of IRIS. The IPSR concept of IRIS is characterized by the inclusion of the entire primary system within a single pressure vessel, including the steam generators and pressurizer. The CNEN team is responsible for the internal pressurizer design and for the review of RELAP5 input file. The design tasks for the pressurizer have included steam-water volume sizing, pressurizer to vessel physical separation by an internal thermal insulation, surge connections dimensioning and transient analyses. This paper presents a very brief description of IRIS, and a summary of CNEN activities in this project. (author)