More stringent safety requirements for Civil Works of future nuclear buildings combined with severe design loads lead to continuously increase the steel bars demand in Reinforced Concrete (RC) structures. The related implementation issues during the detailed design and the construction create for the projects both delays and cost escalation.

As a consequence trend in nuclear civil engineering is to resort more often to Steel Concrete (SC) structures when large steel reinforcement ratios are anticipated from the preliminary design of a RC structures. These prefabricated modules (steel part) could also replace a large part of the embedment parts for moderate loads that reach the outstanding quantity of 100.000 plates for the recent Nuclear Power reactor projects and bring a solution for containment (liquid or gas).

One main advantage is also a gain on the construction schedule as the steel modules are prefabricated and in situ construction operations are limited to the connection of the steel modules and the infill concreting.

SC modular structures are entering in the frame of ongoing nuclear projects like ASTRID, the Generation IV Sodium cooled Fast Reactor industrial demonstrator under development by the CEA in France. The civil work design of ASTRID is based on Eurocodes and more specifically on AFCEN Rules for design and construction of PWR nuclear civil works (RCC-CW). Preliminary studies (design and construction methodology) have demonstrated the feasibility to realize in SC different structural parts. CEA and BOUYGUES Company are currently working to benchmark the pros and cons of the SC modules in ASTRID against a reinforced concrete structure, focusing on construction methods, and subsequently to define the cost and schedule impacts.