Nuclear propulsion and research

Nuclear propulsion

In this area of expertise, we provide technical expertise for the safe and reliable operation of nuclear reactors for military propulsion purposes – for example in nuclear-powered submarines and aircraft carriers.

NASA’s new space programs, which are preparing for the conquest of space, do not overshadow nuclear-propulsion, a field that has been the subject of numerous, mainly naval, military and civil programs.

In marine applications, the first nuclear-powered submarine, the USS Nautilus, went into operation in 1955.

Since then, nearly 600 ships have been designed.

The French fleet is made up of eleven ships in operation, each equipped with nuclear reactors. It includes:

  • Four new generation ballistic missile submarines equipped with nuclear reactors (SSBN – Le Triomphant)
  • Six nuclear attack submarines (SSN – Rubis class)
  • The aircraft carrier Charles de Gaulle

The technology adopted for naval nuclear propulsion is mainly in the form of pressurized water reactors (PWR) of the same type as our nuclear plants, but with several hundred megawatts for the largest ships as opposed to 900-1450 MW for French nuclear power plants. The reasons that led to the choice of this technology are numerous, but the main one is the very great autonomy it gives the vessels. They are able to remain submerged for several months and provide high diving speeds over long distances; avoiding the need for submarines to come to the surface to feed air into engines; the engines are also quieter and therefore more discreet than diesel engines.

The current SSN fleet will be replaced from the beginning of 2017. This is the focus of the Barracuda program, launched in development and in production at the end of 2006. This program is jointly run by France’s Directorate General of Armaments (DGA) and the Military Applications Division of CEA (DAM) in Cadarache. An order for four submarines is ongoing. In this context, the DAM (Direction des Applications Militaires) is responsible for the design and production of the nuclear boilers and the associated reactor cores, as well as for all the logistics required to maintain them.

In the Barracuda project, Sofren was involved in the design of the reactor containment structure and was recognized for its expertise.



Our teams are involved in sensitive research projects on new generation nuclear power plants and issues related to reprocessing nuclear waste.


Research is a key component for the electronuclear power industry, given the major issues for the development of even more reliable and innovative technologies, the sustainability of the sector and its acceptance by the public (recycling, waste reprocessing, safety, etc.).

The main objective is reducing the impact on the environment and on the population. The research covers the entire fuel cycle. Upstream, it focuses on changes in fuel: the use of new combustibles (elements / isotopes), the development of sheaths and matrices.

Back-End of the cycle, research focuses on waste treatment (developing new separation and packaging methods), transmutation of waste to reduce toxicity, and storage solutions (behaviour of materials in the long-term and packaging / environment interactions).

Research also focuses on developing a new generation of nuclear plants (including being embedded in the current fuel cycle or establishing new dedicated cycles. To this is added nuclear fusion, which is promising in terms of profitability and safety, despite the significant technological barriers.

Finally, in the biological and medical field, research focuses on the impact of ionizing radiation on living organisms and its use in radiotherapy. The research thus covers a multitude of areas: geology, chemistry, materials, thermal hydraulics, neutron transport, particle physics, electromagnetism, plasma, biology, etc.

In the research sector, SOFREN positions itself mainly on the back-end part of the cycle, with many projects covering waste packaging processes and effluent treatment. On behalf of AREVA NC, AREVA SGN, CEA.

These activities cover the entire process, from the development or optimization of procedures, performing tests and analysing the results. The engineers involved in these projects have expertise in chemistry, materials, and processes.


nuclear-powered submarine