Pioneering Role of IRIS in the Resurgence of Small Modular Reactors^*

^*This paper summarizes the work of many who contributed their talent, time, and efforts to advance the IRIS project as well as the small modular reactor technology and nuclear power in a broader sense. The leading force in envisioning, guiding, and directing the IRIS project from its inception was Mario Carelli, chief scientist atWestinghouse Electric Company. Additionally, more than a hundred experts in their respective fields, from more than 20 IRIS team “core organizations” and about 10 additional organizations, participated in IRIS development, together with more than a hundred students who performed research related to IRIS. Their work is documented in more than 500 journal and conference papers, technical reports, and theses. Regretfully, it is not feasible to give the well-deserved credit by name to all individuals and organizations. Instead, we tried to point out only a selected subset of activities and contributions. A limited number of references provided at the end of the paper may serve as a starting point to IRIS literature search to interested readers.

Abstract

This paper presents an overview of the first 10 years of the IRIS project, summarizing its main technical achievements and evaluating its impact on the resurgence of small modular reactors (SMRs). SMRs have been recurrently studied in the past, from early days of nuclear power, but have never gained sufficient traction to reach commercialization. This situation persisted also in the 1990s; the focus was on large reactors based on the presumed common wisdom of this being the only way to make the nuclear power plants competitive. IRIS is one of several small reactor concepts that originated in the late 1990s. However, the specific role and significance of IRIS is that it systematically pursued resolving technology gaps, addressing safety, licensing, and deployment issues and performing credible economics analyses, which ultimately made it possible—together with other SMR projects—to cross the “skepticism threshold” and led the making of a convincing case—domestically and internationally—for the role and viability of smaller reactors. Technologically, IRIS is associated with a number of novel design features that it either introduced or pursued more systematically than its predecessors and ultimately brought them to a new technical level. Some of these are discussed in this paper, such as the IRIS Safety-by-Design, security by design, the innovative thermodynamic coupling of its vessel and containment, systematic probabilistic risk assessment-guided design, approach to seismic design, approach to reduce the emergency planning zone to the site boundary, active involvement of academia, and so on. Many individuals and organizations contributed to that work, too many to list individually, and this paper attempts to pay tribute at least to their collective work.

Notes

^* This paper summarizes the work of many who contributed their talent, time, and efforts to advance the IRIS project as well as the small modular reactor technology and nuclear power in a broader sense. The leading force in envisioning, guiding, and directing the IRIS project from its inception was Mario Carelli, chief scientist atWestinghouse Electric Company. Additionally, more than a hundred experts in their respective fields, from more than 20 IRIS team “core organizations” and about 10 additional organizations, participated in IRIS development, together with more than a hundred students who performed research related to IRIS. Their work is documented in more than 500 journal and conference papers, technical reports, and theses. Regretfully, it is not feasible to give the well-deserved credit by name to all individuals and organizations. Instead, we tried to point out only a selected subset of activities and contributions. A limited number of references provided at the end of the paper may serve as a starting point to IRIS literature search to interested readers.