IRESNE's website

Our research​

The teams at the Research Institute for Nuclear Systems for Low-Carbon Energy Production (IRESNE) support their colleagues at the Military Applications Division (DAM).​

The DAM is responsible for the project ownership of on-board nuclear boilers. Our wealth of know-how and skills in the research and development of civil nuclear reactors can be applied to the specific needs of on-board nuclear reactors.

Computer codes for nuclear propulsion

Within the scope of optimising current and future boilers for nuclear propulsion, our scientists are constantly striving to improve and validate thermohydraulic and neutronic calculation packages in this field.

The RES test reactor is equipped with in-core instrumentation that allows us to collect data in real time thanks to the twenty or so measurement points distributed throughout the reactor core. This information is sorted, analysed and used to validate and then improve the accuracy of the code packages.​

Characterising fuels

A fuel storage pond has been built next to the test reactor. It is equipped with a gamma test bench called BANGA. This measuring tool helps us to determine the fuel’s irradiation rate without having to carry out any destructive tests. These non-destructive examinations provide ample information on what the fuel undergoes during its lifetime, thus making it possible to continue our fuel optimisation process.

Dose measurement and analysis

Dose measurement and analysis helps us to determine the dose of ionising radiation that the material has absorbed following its exposure. To do this, we use our experimental platform called MADERE to take X-ray and gamma spectrometry measurements.

Digital tools to model severe accidents

The data collected from tests performed in the RES reactor is used to develop digital tools that can model severe accidents. These models help us to better understand such accidents and develop preventive measures.

Optimising materials and components

Reactor core safety is our overriding concern.

IRESNE is tasked with testing the performance of valves designed for on-board nuclear boilers. We use the water-steam thermohydraulic and hydromechanical research platform called POSEIDON.

The data collected from tests performed in the RES reactor provides us with valuable information on the heat exchange conditions between fluids and the NSSS components. This information is used to validate computer codes used to model system thermohydraulics.

Reactor core and fuel studies

Our objective: predict the behaviour of the core and its fuel

The results of our research are used to qualify the thermomechanical behaviour of fuels and to validate software designed to simulate the behaviour of the core and its fuel. All this research comes together to improve the performance of on-board nuclear boilers and demonstrate their overall safety.

Our teams are actively contributing to fuel design, manufacturing and characterisation activities.

 
We also have teams focusing on reactor core and fuel models developed to check and validate the robustness of previously established nuclear safety criteria. In this field, the scientists at IRESNE tend to rely on separate-effect tests to assess the behaviour of the nuclear fuel. These tests are designed to validate the physical models in computational tools under conditions where the dominant physical phenomena identified are said to be isolated.

The computer codes used to simulate fuel behaviour can then be validated.

The POSEIDON platform is also used to conduct experiments simulating accident conditions, e.g. studies on reactor vessel cooling and in-core accident management.

THEMIS: a thermohydraulic test loop

The future test loop called THEMIS is currently in its design phase. It will be used to conduct two-phase (water-steam) thermohydraulic tests under high temperature and pressure conditions, which are representative of on-board nuclear boilers. This test loop will belong to the POSEIDON experimental platform, which was built to study the mechanical and hydraulic characteristics of core and system components in normal and accident conditions.

Preparing irradiation experiments in the Jules Horowitz reactor (JHR)

Reactor vessel resistance

The Jules Horowitz reactor (JHR) is currently under construction at the CEA Cadarache centre; it will be one of the only test facilities worldwide able to offer the possibility of performing irradiation experiments on materials.

Being able to predict the behaviour of materials subjected to neutron bombardment (when irradiated) is crucial to nuclear safety. Neutron bombardment leads to a collision cascade of atoms in the materials making up the reactor components, therefore provoking a change in their initial characteristics. It is important to be able to study changes in the resistance of the materials used to manufacture the steel reactor vessel (in which the reactor cores is installed). The robustness of these materials during the reactor’s entire lifetime is key to its safety because this component cannot be replaced.​