The impact of the concept of modularity in reducing the cost of small, replicated, and mostly factory-built units is paramount. Proponents refer to this as the competition between the traditional economy of scale which has led to GWe-sized plants and the new economy of numbers which characterizes the construction of SMRs.

Further, the dramatically reduced power rating of SMRs provides significant potential for passive safety systems which simplify or eliminate active safety systems compared to those of current-generation reactors. As well, the SMRs can eliminate their reliance upon support systems as compared to the current LWRs’ need for such systems. The American Nuclear Society’s report on SMR generic licensing issues (see Tables 1.3 and 1.4 in American Nuclear Society, 2010) identifies specific candidate safety and support systems for such simplifications and eliminations. However, projections among analysts vary as to whether SMRs can achieve lower LUECs than traditional large plants. For example the OECD has reported (OECD, 2011) that the investment component of LUEC from an SMR would probably be higher than that of a large plant, even taking into account the SMR reduced construction schedule, shop fabrication, and learning curve. Further, the OECD concluded that SMRs, including twin-unit and multi-module plants, generally have higher values of LUEC than nuclear power plants with larger reactors. Thus achievement of a competitive SMR LUEC will be very difficult to accomplish: reference to independently validated projections is essential for developing realistic cost estimates.