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Key principles

The CEA is tasked with designing and building nuclear reactors for the French navy’s ships, i.e. submarines and aircraft carriers.​​

The Research Institute for Nuclear Systems for Low-Carbon Energy Production (IRESNE) leads studies on fuels and reactors for nuclear propulsion under the supervision of the CEA Military Applications Division (DAM). The latter is the contracting authority for all nuclear steam supply systems (NSSS) used in nuclear propulsion.

Nuclear propulsion

Several hundred navy ships and submarines worldwide are powered with on-board nuclear reactors. This method of power generation is perfectly suited to the French Navy’s fleet, which often needs to spend lengthy periods of time out at sea without being able to stop for refuelling. Nuclear energy is an unobtrusive, long-range and responsive power source - everything a navy ship needs to complete its missions.​

An on-board reactor: a nuclear steam supply system

Reactors that provide nuclear propulsion are also known as on-board nuclear steam supply systems (NSSS) or nuclear boilers in the industry. They are located at the aft (rear) of the ship and are required to meet some very stringent constraints, which explains why so much research and development has been invested in them.

Specificities of a nuclear steam supply system

On-board reactors must comply with several criteria:

• Compactness:
  It must be possible to install them in an extremely small space.
  




• Flexibility:
  




• High availability:
  Reactors provide an excellent availability rate. This is possible by increasing the reactor core’s service life, which also allows for longer operational periods between maintenance outages.
  




• Nuclear safety:
  The overriding objective is the nuclear safety of the facility, whether submerged or not. Reactors must be safe at all times.
  




• High-performance:
  On-board reactors must reach high levels of operational performance. For instance, this can involve improving the vessel’s acoustic signature.​
  
  

Synergies with our strategic partners

The CEA is supported by two key industry players in this field: TechnicAtome and Naval Group.

TechnicAtome is responsible for project management, designing the nuclear steam supply systems and cores, manufacturing the fuel, and acting as technical operator of the land-based test facilities on behalf of the CEA, the operator.

Naval Group is the architect-engineer of the vessel; it manufactures the pressurised systems comprising the NSSS and is responsible for making sure they remain operational on all naval sites belonging to the French Navy.

The RES: a nuclear propulsion test reactor

Nuclear reactors used to generate electricity can also be equipped with on-board instruments to perform online measurements during operation. This valuable data is then used to improve our computer tools and know-how in the nuclear field.

However, this is not the case for on-board nuclear reactors. They are not designed to host measuring instrumentation. This is why the CEA built a test reactor facility so it could carry out studies in this specific area. This facility is located at the CEA Cadarache centre. It includes various measuring instruments, a pool and a workshop all used to study this type of reactor and its fuel. The objective is to optimise the current and future nuclear steam supply systems for nuclear propulsion.

The mission statement for the RES is to support the fleet in service, to qualify the fuel and cores of on-board NSSS, to develop and qualify technical innovations for tomorrow’s nuclear propulsion, and to safeguard know-how in this field.

Learn more about research for the French defence sector at IRESNE.