Workpackage 6
Hazard: dispersion, reactivity, deposition of radionuclides 


Leaders laboratories: PhLAM, PC2A
Participants: LASIR

 

Contact
 
Valérie Vallet        Laurent Gasnot
PhLAM                    PC2A

Scientific objectives

Introduction

Materials and methods

Ongoing studies and results

Key publications


 

Scientific objectives

During an accidental situation on a nuclear facility, the release of radioactive materials into the atmosphere may occur. The scientific objective of the WP6 is mainly to evaluate (1) the kinetic way of formation of such specific aerosols, and (2) their impact on air quality, health, and climate change. To achieve this goal, it is necessary to characterize the radionuclides that may be emitted, determine their speciation, reactivity properties, and understand their kinetic behavior and dispersion mechanisms in the atmosphere.

 
IBBCEAS cell for I2 measurements         Hydrogen/iodine premixed flame

 
Calculation facilities                               CHIP device (IRSN)

Illustration : Pictures of the experimental devices used to characterize fission products and the computing facility used to run theoretical models (quantum dynamics)


Introduction

Fukushima accident in March 2011 reminded the necessity to be able to evaluate the source term but also the evolution of the behavior of radionuclides once they have been released to the environment. Herein, the “source term” describes the speciation and the amount of radionuclides that can be accidently released to the environment in case of severe accident in a nuclear power plant. Both the reactivity and dispersion mechanisms in environment, and the impact of the release on health strongly depend on the physical and chemical properties of each radionuclide under gaseous or/and aerosol form. The chemical speciation of these specific compounds at short or long distance from the accidental source greatly impacts the contamination and so the procedure to be taken to protect people. On this issue, the nuclear problematic clearly join the “classical” atmospheric pollutant one. Undeniably the chemical and physical properties of fission products play an important role on modes of reactivity, dispersion and deposit of radionuclides. So the main purpose of WP6 is to contribute to a better understanding of the kinetic behavior of representative radionuclides by determining their thermo-kinetic via numerical or experimental complementary approaches.


 

Materials and Methods

Laboratory equipements:

  • Experimental devices to characterize fission products: specific experimental set-up, analytical techniques, metrology
  • Study and characterization of aerosols involving fission products and radionucides
  • Specific chamber to study reactivity between sodium aerosols and gaseous iodine
  • Raman Micro-Spectrometer
  • Optical levitation cell
  • Access to the experimental faciliies of the french Institute for Radiological Protection and Nuclear Safety (IRSN) via the C3R lab (IRSN/CNRS/Lille 1 joint research unit).

Theoretical approach:

  • Theoretical models (quantum, dynamics) to describe radionuclides reactivity with atmospheric aerosols (dust, pollutants, photolysis products, etc); calculation of thermo-kinetic properties
  • Chemical – transport models
  • Clusters and scientific computing facilities

Ongoing studies and results

  • Kinetic modeling of the behavior of iodine in the primary circuit of a Pressurized water reactor (PWR)
  • Characterization of the {Cd, Mo, Cs, I, O, H} system under oxidizing (H2O) or reducing (H2) conditions
  • Study of the chemical systems including Mo, Ag, In et Cd elements
  • Modeling of the behavior of ruthenium in the primary nuclear circuit.
  • Study of the dynamics of Cs in negative ions sources (use of the ITER facility)
  • Theoretical modeling of thermodynamics of volatile plutonium species. Formalism and implementation of Frozen Density Embedding (FDE) to compute molecular properties
  • Chemical interaction between sodium aerosols and gaseaous iodine
  • Experimental study of the re-vaporisation of fission products deposits (Cs, I)
  • Atmospheric chemistry of iodine and halogens
  • Theoretical study of the microhydratation process of iodinated compounds
  • Numerical study of the reactivity of HI with alkyl radicals, and OH radicals with alkyl halides
  • Numerical study of reaction mechanisms in the gas phase involving iodine oxides and nitroxides
  • Development of a chemical mechanism for iodine transport and reactivity in the atmosphere

Illustration : Global strategy to describe iodine transport and reactivity in the atmosphere.


Key publications

  • Jung, H.-J., Eom H.-J., Kang H.-W., Moreau M., Sobanska S. and Ro C.-U.: Combined use of quantitative ED-EPMA, Raman microspectrometry, and ATR-FTIR imaging techniques for the analysis of individual particles, Analyst, 139, 3949-3960, 2014.
  • Sudolska, M., Louis, F., Cernusak, I.: Reactivity of CHI3 with OH Radicals: X-Abstraction Reaction Pathways (X = H, I), Atmospheric Chemistry, and Nuclear Safety, J. Phys. Chem. A, 118, 9512-9520, 2014.
  • Šulka, M., Cantrel, L., Vallet, V.: Theoretical Study of Plutonium (IV) Complexes Formed within the PUREX Process: A Proposal of a Plutonium Surrogate in Fire Conditions, J. Phys. Chem. A, 118, 10073, 2014.
  • Sulkova, K., Federic, J., Louis, F., Cantrel, L., Demovic, L., Cernusak, I.: Thermochemistry of small iodine species, Phys. Scripta, 88, 058304, 2013.
  • Vallet, V., Masella, M.: Benchmark binding energies of ammonium and alkyl-ammonium ions interacting with water. are ammonium–water hydrogen bonds strong?, Chem. Phys. Lett., 118, 168–173, 2015, doi: 10.1016/j.cplett.2014.11.005.
  • Zanonato, P. L., Di Bernardo, P., Vallet, V., Szabó, Z., Grenthe, I.: Alkali-metal ion coordination in uranyl(vi) poly-peroxide complexes in solution. part 1: the Li+, Na+ and K+ - peroxide-hydroxide systems, Dalton Trans., 44, 1549–1556, 2015, doi:10.1039/C4DT02104E.
  • Miradji, F., Souvi, S., Cantrel, L., Louis, F., Vallet, V.: Thermodynamic properties of gaseous ruthenium species, J. Phys. Chem. A, 119, 4961–4971, 2015, doi: 10.1021/acs.jpca.5b01645.
  • Sulkova, K., Cantrel, L., Louis, F.: Gas-phase Reactivity of Cesium-Containing Species by Quantum Chemistry, J. Phys. Chem. A, 119, 9373-9384, 2015, DOI: 10.1021/acs.jpca.5b05548.
  • Grégoire, A. C., Kalilainen J., Cousin F., Mutelle H., Cantrel L., Auvinen A., Haste T., Sobanska S.: Studies on the role of molybdenum on iodine transport in the RCS in nuclear severe accident conditions, Annals of Nuclear Energy, 78, 117-129, 2015, DOI : 10.1016/j.anucene.2014.11.026