IRSN, Institut de radioprotection et de sûreté nucléaire

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Enhancing Nuclear Safety


Research programmes

CHIP Facility Analytical Line

The CHIP programme aims to better quantify the amount of iodine that may be released (source term) during a core meltdown accident in a nuclear reactor. The "analytical" line studies the chemical mechanisms involved in the formation of iodine species for homogeneous gas-phase reactions of quaternary systems (I, O, H) by means of pre-mixed flame configurations.

Test objectives


This programme will make it possible to:

  • Ascertain basic kinetic data for mixtures containing iodine, hydrogen, and steam;
  • Supplement the databases (chemical speciation of gaseous iodine species and basic kinetic data) needed to model the behaviour of radioactive fission products in the primary cooling system of a pressurised water reactor (ASTEC software developed by IRSN/DPAM).



Experimental device and test condition


The device includes:

  • Several reagent feed pipes (iodine from a hydrogen iodine (HI) cylinder, hydrogen/ steam generator, O2 combustive agent from a gas cylinder, other reagents such as Cs, Cd, etc.);
  • A burner supplied with a premixed gas mixture ensuring the formation of a 1D flame in which the reagents can react;
  • A low-pressure combustion chamber;
  • On-line gas sampling systems;
  • Analytical devices for identifying and quantifying the species under investigation (molecules, atoms and radicals).


This device is used to determine quantitative profiles of change in chemical species as a function of the temperature profile in the flame. The experimental data are used to develop complex reaction mechanisms. The experimental parameters are the temperature (500 - 2,000 K) and the concentration ratios of the chemical reagents. They are representative of the different ranges covered under accident conditions in the primary cooling system of a pressurised water reactor.

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