On the Many Meanings of Modularity

Abstract

The modularity of Small Modular Reactors (SMRs) aims at either allowing off-site manufacturing and on-site installation, and/or permitting incremental deployment of units with moderate initial financial commitment. This paper shows that there are various forms and definitions of modularity that can make it ambiguous to know what exactly modularity means in the context of SMRs. The definition of modularity as incremental installation of units to form a large plant offers economy of multiples that competes with the traditional concept of economy of scale. It is argued that though the modularity of design offers some efficiency and safety advantages, it can result in overdesign and hindrance of further improvement and innovation. The 1-3-8 rule of modular manufacturing advocated by the shipbuilding industry is presented. It is asserted that the advantages of modular construction can only be attained with careful project management, but can increase the cost of transportation of components and materials. Given the many ways of defining modularity, which are listed in the paper, the concept of modularity in SMRs should be clearly and concisely defined and articulated by the vendors. Learning from the installation of a few units of a kind will enhance the benefits of modularity in subsequent constructions.