Does “smaller” actually mean “more modular” in nuclear power? Our latest research exploring this question revealed some fascinating insights about the complex scaling relationships in nuclear plant design.
A core promise of Small Modular Reactors (SMRs) is their ability to shift more work to factories and away from construction sites. However, our detailed analysis of reactor designs found that larger reactors have a higher ratio of offsite to onsite work than their smaller counterparts.
The insight emerged from water cooler conversations at Alva about a fundamental challenge in nuclear scaling: civil structures and site improvements don’t scale down proportionally with reactor size. For example, the BWRX-300’s reactor building is about 1/3 the size of the ABWR but outputs 1/4 or 1/5 the power. The AP1000 demonstrates this scaling benefit in reverse – it required only an 11% cost increase over the smaller AP600 but delivered almost 80% more power.
This creates an important dynamic: as reactors get smaller, certain aspects of construction – particularly civil works, foundations, and site improvements – remain predominantly onsite activities and don’t shrink linearly with reactor size. Some building dimensions are driven by human access requirements, seismic criteria, and shielding that don’t scale linearly with power output. This affects the balance between onsite and offsite work in complex ways that challenge conventional assumptions about modularity.
And listen to our CEO, @James Krellenstein, discuss these factors on the podcast Decouple.
