IRIS (International Reactor Innovative and Secure) - design overview and deployment prospects

The International Reactor Innovative and Secure (IRIS) is an advanced, integral, lightwater cooled, pressurized reactor of medium generating capacity (1000 MWt, or about 335 MWe). It has been under development since the turn of the century by an international team - led by Westinghouse - that includes 19 organizations from 10 countries. In year 2002 it has initiated the pre-application review with the U.S. Nuclear Regulatory Commission (NRC), aiming at final design approval around 2010, and deployment in next decade (about 2015), consistent with the prediction of the growing energy supply gap in both developing and developed countries. This paper describes the reactor layout (i.e., its integral design, with the steam generators, pumps, pressurizer and control rod drive mechanisms all included inside the reactor vessel, together with the core, control rods, and neutron reflector/shield) and discusses the unique safety-by-designTM IRIS philosophy. This approach, by eliminating accidents at the design stage, or decreasing their consequences and probabilities when outright elimination is not possible, provides a very powerful first level of defense in depth. The ''safety-bydesign'' TM allows a significant reduction and simplification of the passive safety systems, which not only improves its safety but simultaneously reduces the overall cost. Moreover, it supports licensing the power plant with reduced off-site emergency response requirements. The modular IRIS - with each module rated at ∼335 MWe - is an ideal size for smaller energy grids as it allows introducing sequentially single modules in regions only requiring a few hundred MWs at a time. IRIS naturally can be also deployed in multiple modules in areas requiring a larger amount of power increasing with time, thus fulfilling the needs of larger, developed countries as well. The performed top-down economic analysis indicates that the cost of generated electricity is competitive with other nuclear and non-nuclear power plants. With its moderate size and short construction time, IRIS significantly reduces the financial burden and presents a viable solution for markets (or countries) with limited investment capital. (author)