CEA spins off two companies for SMR development

10 March 2023

The French Alternative Energies and Atomic Energy Commission (CEA) has spun off two nuclear start-ups - Hexana and Stellaria - for the development of small modular reactors (SMRs).

The Hexana team: Paul Gauthé , Jean-Baptiste Droin and Sylvain Nizou (Image: CEA / L Godart)

Hexana aims to develop an SMR featuring a sodium-cooled fast neutron reactor, integrated with a high temperature storage device. A plant would comprise two of these reactors (400 MWt each) supplying a heat storage device. An adjoining conversion system will allow it to produce electricity on demand and in a flexible manner to compete with gas-fired power plants, but also to supply heat directly to nearby energy-intensive industries.

CEA said fast neutron and sodium-cooled reactors are of "major interest in the management of nuclear materials: they operate without natural or enriched uranium but with depleted uranium combined with plutonium from reprocessed fuel from the French nuclear fleet (MOX)".

It added: "These reactors will thus contribute to energy sovereignty and to the reduction of the volumes of high-level nuclear waste in a logic of closing the nuclear fuel cycle."

Meanwhile, Stellaria aims to develop an energy system based on a chloride molten salt reactor (MSR).

The Stellaria team: Guillaume Campioni, Lucas Tardieu and Nicolas Breyton (Image: CEA / L Godart)

MSRs use molten fluoride salts as primary coolant, at low pressure. They may operate with epithermal or fast neutron spectrums, and with a variety of fuels. Much of the interest today in reviving the MSR concept relates to using thorium (to breed fissile uranium-233), where an initial source of fissile material such as plutonium-239 needs to be provided. There are a number of different MSR design concepts, and a number of interesting challenges in the commercialisation of many, especially with thorium.

The salts concerned as primary coolant, mostly lithium-beryllium fluoride and lithium fluoride, remain liquid without pressurisation from about 500°C up to about 1400°C, in marked contrast to a pressurised water reactor which operates at about 315°C under 150 atmospheres pressure.

The main MSR concept is to have the fuel dissolved in the coolant as fuel salt, and ultimately to reprocess that online. Thorium, uranium, and plutonium all form suitable fluoride salts that readily dissolve in the LiF-BeF2 (FLiBe) mixture, and thorium and uranium can be easily separated from one another in fluoride form. Batch reprocessing is likely in the short term, and fuel life is quoted at 4-7 years, with high burn-up.

The reactor proposed by Stellaria will be very compact - measuring 4 cubic metres - and, like Hexana, will be able to use a diversified range of nuclear fuels (uranium, plutonium, MOX, minor actinides, even thorium), "thus fitting perfectly into the French strategy of closing the cycle". The reactor will produce 250 MWt.

The CEA intends to find partners beyond the nuclear sector for these two start-ups, which will be able to apply for the France 2030 call for "innovative nuclear reactors" projects: a programme endowed with EUR500 million (USD534 million) which will part of the government's desire to close the nuclear fuel cycle, Maddyness reported.

In February 2022, President Emmanuel Macron announced that the time was right for a nuclear renaissance in France, saying the operation of all existing reactors should be extended without compromising safety and unveiled a proposed programme for six new EPR2 reactors, with an option for a further eight EPR2 reactors to follow.

In addition, Macron said EUR1.0 billion will be made available through the France 2030 re-industrialisation plan for France's Nuward small modular reactor project and "innovative reactors to close the fuel cycle and produce less waste". He said he had set "an ambitious goal" to construct a first prototype in France by 2030.

Researched and written by World Nuclear News