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Key principles

This reactor is currently being built at the CEA Cadarache centre.

The Jules Horowitz Reactor (JHR) is currently under construction at the Cadarache centre. In addition to the laboratories specialised in characterising irradiated fuels (LECA for IRESNE) and irradiated materials (LECI for ISAS), the JHR represents a fundamental facility for studying the behaviour of fuels and materials to support EDF’s operational fleet of nuclear reactors. As project owner of the construction phase and future operator of the reactor itself, the CEA has already initiated a specific research programme to thoroughly prepare the experiments to be performed in the reactor. IRESNE is tasked with developing and preparing the future fuels experiments, as well as progressively building up the teams in charge of operations and experimentation. Our colleagues from the ISAS institute at the CEA Saclay centre in Paris are working closely with our teams at IRESNE in these fields and more particularly on materials.​

What is the JHR?

The letters JHR stand for Jules Horowitz Reactor.

The JHR is a material test reactor (MTR) that uses water as its coolant and its maximum power will not exceed 100 MWth (megawatts thermal).
This facility will be used by scientists to irradiate fuels and materials at high neutron fluxes in an environment that has been engineered to “speed up” the ageing process to be able to compare with damage levels observed in a power reactor.
The facility will be configured so that several experiments can be performed at the same time in a safe environment, and that the irradiated samples can be analysed onsite. The data collected from the tests performed with be used to analyse the behaviour of power reactor fuels and materials under irradiation.

Why do we study irradiated materials and fuels?

Global needs expressed by stakeholders in the nuclear and reactor safety sectors.

Understanding the behaviour of materials placed in an extreme, hostile environment (high pressure, temperature and radioactivity) is a prerequisite to guaranteeing reactor safety. The materials and fuels are certainly subjected to harsh conditions in a nuclear reactor:

• They are subjected to thermomechanical and chemical loads.
  
• They are irradiated by neutrons.
• The fission products and activation resulting from the nuclear reactions taking place in the nuclear fuel change their physical and chemical characteristics.
  

It is essential to understand all these interactions in order to better manage reactor safety by developing innovative fuels and materials that are increasingly more resistant to the conditions resulting from the ambient radiation.

For instance, nuclear fuel rods must remain leaktight to ensure that no radioactive fission products are accidentally released into the reactor’s primary cooling system. We therefore study the behaviour of fuel rods under the effect of irradiation to be able to identify all the phenomena occurring while the fuel remains in the reactor, whether in normal, incident or accident conditions.

The JHR is designed to meet the needs of scientists from across the world by providing them with facility in which they can conduct tests on samples and qualify components representative of those used in nuclear power reactors in normal, incident and accident scenarios.​

Who is Jules Horowitz?

Jules Horowitz is considered to be one of the founding members of the “French school” of neutronics.

The CEA chose the name Jules Horowitz for this research reactor to honour this French physicist of Polish origin. Jules Horowitz made significant progress in the field of nuclear physics for the CEA.
He was the department head in charge of atomic piles during which time the first French test pile called Zoé was built by the CEA.
In 1970, he set up the Institute for Fundamental Research within the CEA and became its first director. Jules Horowitz is considered to be one of the founding members of the “French school” of neutronics.

A global project

Partners from all four corners of the world.

The JHR project is being built at a time where the obsolescence of most material test reactors (MTR) worldwide is becoming an increasing problem, making it difficult to conduct irradiation experiments on fuels and materials. It was based on this observation that discussions were initiated between the key global nuclear stakeholders, which led to the creation of a consortium of financial partners in 2007 to fund the JHR project. With this partnership, the JHR has become of the first European material test reactors open to international users. In exchange for financial support, partners of the JHR project are given access rights to the reactor so they can conduct their own experiments on the behaviour of materials under irradiation.
The JHR project partners are:

• Key French industry partners: EDF, FRAMATOME, TECHNICATOME and AREVA.^SA.
  
• European Commission.
• Research organisations from the following countries: Belgium, Czech Republic, Spain, Finland, India, Israel, Sweden, Great Britain and China.
  

This new test reactor will provide the experimental resources for the next several decades, which are needed to ensure our ability to continue developing nuclear fission. The experiments performed in this facility will allow us to gain leverage the improvements made in nuclear safety, service lifetime extensions, technical know-how, and cost effectiveness, both for the current fleet of reactors and the future generation of reactor technologies.

For instance, nuclear fuel rods must remain leaktight to ensure that no radioactive fission products are accidentally released into the reactor’s primary cooling system. We therefore study the behaviour of fuel rods under the effect of irradiation to be able to identify all the phenomena occurring while the fuel remains in the reactor, whether in normal, incident or accident conditions.

How is the medical industry concerned?

A producer of radioisotopes for nuclear medicine.

In addition to research, the Jules Horowitz reactor will also play an important role in supplying radioisotopes (especially technetium-99 via the production of molybdenum-99) for the medical industry. As the ageing fleet of test reactors is struggling to the demand for medical isotopes (unplanned shutdowns, some for lengthy periods of time), the JHR project has factored in this major societal need. The JHR is expected to produce about 25 to 50% of the European demand, thereby meeting the medical needs of thousands of patients every day.

Radioisotopes are not only used for diagnostic purposes, but also for treatment. This is known as theranostics, incorporating both diagnostic and therapeutic molecules. Certain radioisotopes such as technetium-99 are used in medical imaging, e.g. scintigraphy (gamma scans), which is a test that analyses how well an organ is functioning. Others such as lutetium-177 are used for therapeutic purposes, in vectorised internal radiotherapy, to treat certain types of cancer.

There are different methods for producing radioisotopes. Irradiation reactors such as the JHR can be used to produce large quantities of radioisotopes at a low cost.


Reminder:
During a nuclear fission reactor, the fuel (uranium-235 in this case) is bombarded with neutrons. The neutrons absorbed by these fissile nuclei provoke the release of more neutrons which in turn are absorbed by other fissile nuclei, thus initiating a chain reaction. The fission of nuclei also produces fission products that are usually unstable. This means that they have too many neutrons so they undergo successive decay to reach a more stable element.

Molybdenum-99 (⁹⁹Mo) usually represents about 6% of the resulting fission products. It decays into technetium-99m (^99mTc) as soon as it is produced.

Ensuring a sufficient supply can prove complex due to their short radioactive decay; molybdenum-99 has a half-life of 66 hours while technetium-99m only lasts 6 hours. It is a race against the clock between the time when the radioisotopes are produced in the reactor and when they are delivered to the hospital.​​

Visit the JHR website.

Learn more about our research around the JHR project.