As seen, multiple SMRs on the same site may be considered as an investment option alternative to a power station based on LRs with the same overall power output. The SMR investment case bears a loss of economy of scale which may be mitigated by some specific cost benefits. These economic benefits, presented in the previous sections, are enhanced by deploying multiple units on a same site. On the construction side, learning accumulation, modularization and co-siting economies are expected to be fostered by the multiple units ‘philosophy’ and the ‘mini-serial production’ of a number of smaller and simpler plant units. In addition, design simplification is expected to further contribute to cost-reduction of SMRs, but its evaluation is strictly plant-specific and deserves further analysis and approaches.

On the investment side, the fractioning of total investment into multiple smaller batches may represent a risk mitigation factor against possible cost/time overruns and an opportunity to adapt the investment plan and the power installed rate to the market conditions. All these economic features may be summarized into an ‘Economy of Multiple’ concept that may counterbalance the ‘Economy of Scale’ philosophy, especially when uncertainty is introduced in the analysis, affecting market conditions or construction process time schedule.

Some concepts apply to the operating and decommissioning cost as well, with a loss of economy of scale to be partially recovered by the simplification of operating or dismantling procedures. SMR design simplification has a relevant impact both on construction and decommissioning costs and any economic assessment that does not take fully into account such issues tends to be very conservative against SMR.