Last update on August 2018
The Laboratory for the Study of Chemical Kinetics, Combustion and Reactivity (C3R) is a joint research laboratory of IRSN, CNRS and University of Lille.
The scientific topics of C3R concern the chemical reactivity of mineral or organic molecules. Its scope ranges from nuclear facilities to the atmosphere and encompasses areas of research developed at IRSN and the PC2A Laboratory.
Background and areas of research
Founded in 2009, C3R solidifies and continues a long partnership between IRSN's Radioelement Transfer Research Laboratory (LETR) and the Physics and Chemistry of Combustion and Atmospheric Processes Laboratory (PC2A/UMR 8522), a joint unit of CNRS and University of Lille. Research, equipment, human and financial resources, as well as the knowledge and know-how of both structures are pooled within C3R.
The C3R employs a staff of 26, of whom 21 are permanent employees (the contribution from PC2A represents 2.5 full-time equivalent staff and 14 permanent employees; while IRSN's share represents an equivalent of 1.5 full time).
C3R is co-directed by Frédéric Cousin of IRSN and Florent Louis of PC2A, who alternate in the posts of director and co-director.
The research carried out by C3R falls into three main areas:
- Chemical kinetics in the gas phase (iodine, ruthenium, etc.);
- Heterogeneous chemistry: The chemical reactivity of aerosols and surface interactions;
Two complementary approaches have been adopted in order to understand and model the complex phenomena that occur during a core melt-down accident, conditions that are difficult to reproduce in a laboratory:
An experimental approach using a number of different experimental facilities: Small-scale experimental facilities, such as a laminar flat flame burner and a falling liquid film reactor, coupled with state-of-the-art analytical techniques, including laser diagnostics based on laser-induced fluorescence and cavity ring-down spectroscopy, and intermediate scale reactors such as the Chip-LP experimental facility dedicated to the study of the reactivity of iodine at high temperature in the presence of particles.
These advanced measurement techniques benefit from a strong contribution in the field of metrology to the development and implementation of analytical techniques, especially the optical expertise made available by the national optical metrology platform (MEOL) in Lille.
- A theoretical approach based on quantum chemistry and statistical simulations of classical molecular mechanics with the aim of interpreting experimental data, developing reaction mechanisms, identifying system effects, and the extrapolation of results beyond the experimental conditions.
In understanding and modelling soot formation, priority has initially been given to an experimental approach in order to build up a database of experimental results. The technique of in situ laser-induced incandescence (LII) will be used to characterise the soot, while the PAHs will be measured by means of mass spectrometry, chromatography and laser-induced fluorescence (LIF).
The chemistry of fission products during a core melt-down accident
A better understanding of the reactivity of the radioelements released during a core melt-down accident in an nuclear reactor, especially those that are the most radiotoxic such as iodine and ruthenium, will facilitate progress in understanding the mechanisms of the chemical reactions in which they are involved and which influence their behaviour. The ultimate aim is a more accurate prediction of the source term, i.e. the discharge of any of these radioelements into the environment.
One important task is to improve the modelling of the transport of iodine in the reactor coolant system. The fluid in which the iodine is transported is a complex oxidising or reducing medium containing a large number of chemical elements in the form of aerosols, vapour and gas. The temperature of this medium may vary dramatically as it circulates through the reactor coolant system. The improvement of these models, especially by taking into account the kinetic parameters of the chemical reactions taking place in the gas phase, should result in a better speciation of the iodine in the vicinity of the breach in terms of both the gas/aerosol distribution and the chemical compounds formed.
This work will eventually be incorporated into the ASTEC (Accident Source Term Evaluation Code) simulation software used to evaluate the discharge of fission products in the event of an accident.
Chemistry of halogenated compounds in the environment
In the event of an accident, one of IRSN's missions is the assessment of radiological consequences linked to emissions of fission products from the facility. The assessment is dependent on a number of factors (meteorology, quantity, deposits, chemical form) as the Fukushima accident in March 2011 demonstrated. One important point in the assessment is the behavior of halogenated species, in particular iodine, after the release. The reactivity of iodine is very important in the environment and results in various species (organic, inorganic, particulates) with different deposition velocities.
Better understanding of the various iodized species in the atmosphere should allow for a better assessment of the consequences in the event of an accident.
The work carried out within this framework should enable long-term improvements in software used in an accident situation (C3X platform).
Topics to be studied in the period 2018-2020
- Determination of the thermo-kinetic parameters and the development of reaction mechanisms for modeling the chemical reactivity of iodine in a reactor coolant system and the environment.
- Determination of gas/particle interactions for iodine in the environment.
- Physical and chemical properties of the oxides and nitroxides.
- Theoretical chemical modelling of surface-particle interactions.
Facilities and techniques
- Available theoretical chemistry software (Gaussian03 and Molcas 7.0) for the quantum modelling of molecules and reactions in the gas phase with access to the molecular properties and the thermo-kinetic parameters of the elementary reactions.
- Experimental facilities dedicated to homogeneous and heterogeneous (particle-gas) chemistry.
- A range of high-performance analytical techniques, including chromatographic approaches, spectroscopic methods, and laser diagnostics in association with MEOL.
- Comenius University of Bratislava
- Laboratory of Excellence CaPPA