Advanced Nuclear Technology Cost Reduction Strategies and Systematic Economic Review #2: Design Modularity At Scale - 2022

Advanced Nuclear Technology Cost Reduction Strategies and Systematic Economic Review (ANTSER) uses a methodological framework for evaluating nuclear cost reduction strategies. ANTSER has been described and implemented in detail, with an initial study related to the design of advanced nuclear power plants that addresses functional containment. This report was produced by the GIF Economics Modelling Working Group (EMWG) in 2022. 

The present study adds to the ANTSER framework through an investigation of modularity for nuclear energy applications at different scales. Modularity can include the incorporation of all major safety-significant systems within one module, standardized modules and factory fabricated modules, the capacity to add modules to increase power output, and the consolidation of components resulting in less on-site construction. Modularity is a topic of interest in the commercial nuclear energy sector with the emergence of small modular reactors. However, the economic viability of these reactors has not been proven to date. Focusing on reactor modularity alone is insufficient to improve the cost competitiveness of nuclear energy technologies. Historically, modularity has been limited to the balance of plant for large-scale nuclear plants, such as steel-plate composite walls. These technologies have achieved limited success because of the need for extensive on-site capabilities. Modularity applications for small to medium- and micro-scale plants are less well-known given their limited deployment. 

Modularity options for traditional nuclear energy deployment have been limited as a result of conventional light water reactor safety requirements, such as those related to high-pressure retaining, heavy and robust containment structures. However, a relatively new regulatory approach called "functional containment" - the focus of ANTSER Cost Reduction Strategy No. 1 - has the potential to allow less expensive and more flexible designs. Functional containment provides flexibility in design and deployment based on risk-informed and performance-based criteria so that reactors are not over designed. The non-nuclear industry has successfully used modular design approaches in automotive, aerospace, chemical processing, building construction, and shipbuilding. These industries have shown that modular construction reduces construction time by around 30%-50% compared to the conventional stick-built approach. Using a similar approach, through functional containment balanced with safety requirements, the nuclear industry could also reduce construction times and costs. 

This study produces ANTSER cost reduction strategy no. 2, focusing on the use of modularity approaches to reduce the cost of Generation IV nuclear technologies. The study surveys the literature on modularity and describes the different ways that modularity has been used or considered for nuclear plants. Lessons learned from previous uses of modularity in the nuclear industry are used to inform readers on challenges and opportunities involved in extending uses to advanced nuclear technologies. Modularity approaches are surveyed for the highest potential to reduce costs for large-, small-, medium-, and micro-scale nuclear reactors. Successful modularization approaches from other industries are considered from the perspective of their potential transferability to the nuclear sector. The functional containment design approach is explored as a means for designers to rethink how modularity is used in advanced nuclear technologies. Modular approaches, from large to very small scales, and balance-of-plant options are described in terms of their cost reduction potential; their technical readiness and their research, development, and demonstration needs.