Experimental study of particle deposition kinetics in the primary circuit of the CIRENE loop and comparison with OSCAR V1.2 code simulations

Within the framework of corrosion product contamination in PWR, the understanding of mass transfers and particularly the understanding of particle transfers in the primary circuit is of great importance. It is for this reason that the CEA, in collaboration with EDF and AREVA NP, has launched a R and D program involving a specific experiment in the CIRENE out-of-pile loop. This program is focused on particle behaviour. The goal of this preliminary experiment is to estimate particle deposition kinetics in the primary circuit within controlled particle injections combined with in-line particle concentration measurements. This paper presents the experimental results of this new CIRENE test in terms of the kinetics of particle deposition and compares them with the particle deposition rate calculated by the OSCAR V1.2 contamination simulation code, implementing the Beal model. The test conditions, as the particle injection and in-line monitoring methodologies are presented as well. The CIRENE out-of-pile loop, dedicated to the study of corrosion product transfers and deposits on core and steam generator tube surface areas, is a 27-liter mock-up of a PWR primary circuit. It is equipped with a Chemical Volume Control System which allows to settle a particle injection device and an in-line particle counting system for this test. The selected particles are zirconium (IV) oxide, iron (II, III) oxide and nickel in powder forms, and they have been chosen with different range of particle sizes from 0 to 5 μm. The Fe₃O₄ and Ni powders are assumed to be chemically representative of the most relevant corrosion products encountered under solid form in the PWR primary fluid. The ZrO₂ powder has been chosen for its chemically inert behaviour in order to demonstrate the relevance of the injection device and of the particle counting methodology. In this experiment, the thermal-hydraulic parameters and chemical conditions are representative of a French PWR primary circuit operational conditions and series of short duration injections of the relevant fine powders have been carried out under permanent conditions with continuous in-line particle counting. Experimental results of the CIRENE test have led to the main following conclusions: - the first experimental results show the consistency and the reproducibility of the overall particle concentration measurements which enables to validate the particle counting methodology and the powder injection process; - the time constant representative of the particle deposition kinetics deduced from the decrease over time of particle concentrations in the CIRENE primary circuit (an exponential law of the form C = C_oe^-λt) is of the same order of magnitude for fine particles as the one obtained from the CIRENE test simulations with the OSCAR V1.2 code. The particle deposition kinetics modelling implemented in the OSCAR V1.2 code - which is based on Beal model - proved to be validated by this CIRENE experiment by taking into account adjustments against PWR feedback. (authors)