Simulations of corrosion product transfer with the PACTOLE V3.2 code

Abstract

International audienceActivated corrosion products generate a radiation field in PWRs, which is the major contributor to the dose absorbed by nuclear power plant staff working during shutdown operations and maintenance. Therefore, a thorough understanding of the mechanisms that control the corrosion product transfers is of the highest importance. For about thirty years, the French strategy has been based on experiments in test loops representative of PWR conditions, on in-situ gamma spectrometry measurements of the PWR primary system contamination and on simulation code development. The simulation of corrosion product transfers in PWR primary circuits is a major challenge since it involves many physical and chemical phenomena including: corrosion, dissolution, precipitation, erosion, deposition, convection and activation. In addition to the intrinsic difficulty of multi-physics modelling, the primary systems present severe operating conditions (300°C, 150 bar, neutron flux, water velocity up to 15 m.s-1 and very low corrosion product concentrations). The purpose of the PACTOLE code, developed by the CEA in cooperation with EDF and AREVA NP, is to predict the contamination of the PWR primary system. The PACTOLE code allows researchers to analyse the corrosion product behaviour and to calculate the activity in the fluid and the surface activity in the primary system. Nowadays, the PACTOLE code is considered to be not only a tool for numerical simulations and predictions but also one that might combine and organize all new knowledge useful to progress on contamination caused by activated corrosion products. This paper presents the modelling implemented in the PACTOLE V3.2 code. In this version, the chemical aspect has been improved by coupling the PACTOLE code to a chemistry code. Comparisons with in-situ gamma spectrometry measurements of PWR primary systems and studies based on experimental feedback are shown