The deployment options for a small reactor build on one of the key attributes of their design. The small modular reactor (SMR) factory build aspect creates a number of significant advantages during the deployment phase. Delivery of assured modules to a customer site has been claimed as a banner headline, but it is worth reviewing the aspects behind these individual claims to understand the contribution of their worth to the overall deployment:

• time to build;

• risk — schedule risk and cost over-run;

• validation — off-site pre-delivery testing;

• international aspirations;

• Critical path through site activities with modular build.

12.5.1.1 Modularity: addressing schedule and cost risk

For the large part nuclear construction project cost increases and schedule delays have their root in site uncertainty when compared to original plans and cost estimates. Modularity has been offered as the solution to these over-runs.

The Construction Industry Institute defines modularity as ‘work that represents substantial offsite construction and assembly of components and areas of the finished product.’ There are incremental levels of modularity that need to be considered; Graduations of modular construction are as follows:

• Skid — modular skid assemblies of equipment that are delivered to site fully instrumented and validated, requiring little installation and commissioning activity. Within this definition it would also be anticipated that the skids are capable of being delivered to site using conventional transportation networks.

• Super skid — this represents the next increment with larger portions of plant intended to be installed in a building.

• Prefabricated — this is the final step in the definition of modular and would extend to a fully prefabricated module comprising plant equipment in an architecturally complete housing.

Has a modular build approach been deployed already with large nuclear plants? There are elements of modular construction encompassed within large nuclear plants. The Vogtle plant built by Southern Co. in Georgia has utilised a level of off-site modular manufacture. This facility has been established to build modules for the plant in a manner that has the same overall goal. However, the modules for a large nuclear plant are essentially one-off modules, built off-site in a piece-by-piece approach. Without the repeat volume flowing through such a facility it can be argued that module build for a large nuclear plant is an off-site variation to the on-site stick build approach and falls short on delivering some of the goals for the module-build approach advocated for small reactors.

The incorporation of advanced modular construction centres around completely shop-fabricated modules. This method of manufacture is more demanding in terms of upfront planning and management. With greater emphasis on design integration, procurement, manufacturing and construction activities there is less natural opportunity for schedule variation. This modular method of site deployment marries beautifully with the flowline approach bringing about greater schedule adherence.

This modular deployment model is not without consequence. The preliminary and final design activities must remain sealed to allow time for the procurement and delivery activities to be completed. Design change at this point erodes the benefits of the advanced modular approach. The mindset of deployable small reactor manufacturing is driving the product line closer and closer towards commodity-based supply chain design.

Having taken a view on the supply and delivery end of the deployment model, there are equivalent considerations that need to be taken into account with the site implementation.