Oxide Phases Induced by Electron Irradiation of 316L/PWR interfaces at High Temperature and Pression

摘要

A short review of the state-of-the-art literature concerning corrosion relevant to the primary circuit of nuclear pressurized water reactors shows the need of better understanding how changes in the operating conditions may induce change in the oxide layer properties. In the primary coolant circuit of pressurized water reactors (PWRs), irradiation and water radiolysis occurred at high temperature (HT), 280-320°C, and high pressure (HP), 15.5 MPa. The growth of oxide layers in conditions relevant to the PWRs primary circuits is investigated in this work using model 316L stainless steel/PWR interfaces that evolve at high temperature and pressure in electron flux. The present approach uses an electron beam to control the production of radiolytic species at a solid(316L)/liquid(PWR) interface in a high temperature and high pressure (HTHP) electrochemical cell working in the range ～ ([25°C, 1 bar] - [300°C,100 bar]). The cell is designed to record the free electrochemical corrosion potential of the 316L/PWR interface once mounted on the beam-line at the SIRIUS Pelletron (LSI, Ecole Polytechnique, France). The beam energy runs at a given energy that can be chosen in the range (0.5-2.5 MeV) to adjust the energy of the electron emerging in water at the interface. There is no circulation of the water in the cell imposed by in- and out-pumping. The ECP value at the 316L/PWR interface and the hydrogen pressure in equilibrium with the PWR water are measured in-line before, during and after electron irradiation at high temperature and pressure (～300/100 °C/bar). Post-irradiation characterisation of the oxide shows that electron irradiation can indeed induce specific properties both in the structure and composition of the oxide layer formed at the 316L/PWR interface.