IRIS reactor design overview and status update

Abstract

The modular IRIS - with each module rated at ∼335 MWe - is an ideal size for developing countries as it allows to easily introduce single modules in regions only requiring a few hundred MWs, or a moderate amount of power on limited electric grids. IRIS can be also deployed in multiple modules successively at time intervals in areas requiring a larger amount of power increasing with time, thus fulfilling the needs of 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 with limited investment capital. In addition to these top level features, the paper will also present recent accomplishments and focus areas of the current development and detailed design activities. The International Reactor Innovative and Secure (IRIS) is an advanced, integral, light-water cooled reactor of medium generating capacity (1000 MWt, or ∼335 MWe), geared at near term deployment (2012-2015). It has been under development since the turn of the century by an international consortium - led by Westinghouse - that includes 21 organizations from 10 countries, and it is currently in the pre-application licensing process with the U.S. Nuclear Regulatory Commission (NRC). This paper describes its integral design (i.e., steam generators, pumps, pressurizer and control rod drive mechanisms are all included inside the reactor vessel, together with the core, control rods, and neutron reflector/shield) and discusses the unique "safety-by- design"™ 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-by-design"™ allows a significant reduction and simplification of the passive safety systems, which not only improves safety but simultaneously reduces the overall cost. Moreover, it supports licensing the power plant without the need for off-site emergency response planning - an objective which is part of the pre-application with NRC and is also pursued within an international research project coordinated by the International Atomic Energy Agency (IAEA). This would allow IRIS to be treated as any other industrial facility, located closer to population centers, and enable its effective dual-purpose use for electricity production and co-generation (district heating, desalination, industrial steam).