Small Modular Reactors have Combined Cycle Gas Turbine envy

The SMR craze reflects a fundamental category error and combined cycle gas turbine envy. It tries to map the attributes of a CCGT plant onto nuclear, where the underlying cost structure and physical infrastructure is fundamentally different.

A CCGT plant is essentially a jet engine bolted to a heat recovery steam generator and a smaller steam turbine. The critical point is where the complexity sits. The gas turbine, which is the expensive and technically demanding component, is built in a factory, hot functionally tested and shipped to site as a finished machine.

Construction on site is largely installation, foundations, piping, electrical connection, using conventional materials and repeatable processes. That architecture shifts risk into manufacturing and compresses timelines. Rather than building the hardest part on site you are simply installing it in 24-36 months.

Nuclear does not behave this way. It can incorporate modular components, but the NSSS is only 25-40% of cost. The dominant cost drivers sit elsewhere. Civil works, excavation, basemat, containment, seismic qualification, remain site specific and labour intensive. Nuclear grade quality assurance, documentation, and inspection add another layer of fixed overhead. Safety systems with redundancy and independence are function driven, not size driven, so they do not shrink proportionally with output.

The nuclear steam supply system is not analogous to the gas turbine in a CCGT. It is not a fully integrated, factory proven machine that arrives ready to run. The plant comes together on site, under regulatory oversight, with integration, testing and certification happening during construction & commissioning.

This is why economies of scale are so strong in nuclear. Many of the costs do not scale linearly with power. When you reduce reactor size, you reduce output and revenue, while a large share of the cost base remains. Studies show that smaller reactors actually increase the relative share of on site construction because the civil works do not shrink in proportion to capacity.

The SMR thesis assumes nuclear can transition from a project to a product, capturing the modular, factory built economics of gas plants. The constraint is that the parts of nuclear that dominate cost remain stubbornly project based.

The envy is understandble. CCGTs are extraordinarily compelling. They are marvels of thermally efficiency, capital light, fast to deploy and supported by a global supply chain of standardized components. They are the most successful large scale power plants of the past decades.

It is only natural that nuclear developers would look at that model and attempt to emulate it but in so doing they are committing a grave category error, an error that is setting the western nuclear industry up for decade(s) of disappointment.

Some SMRs will get built but they will not replicate the CCGT promise. They will be mini versions of large reactors with mini revenues to pay off the significant inherent costs of nuclear power.