Understanding the evolution of mechanical properties under irradiation in nuclear glasses via experiments

摘要

More than 80％ of France's electricity needs are met via nuclear power plants.Due to France's nuclear power program it maintains a high level of energy independence and one of the lowest costs of electricity in the world.Furthermore,with today's worry about global warming,it also lays claim to an extremely low level of C02 emissions per capita.However a big disadvantage to nuclear energy is the long term storage of the nuclear waste.The high-level wastes are stored in a complex borosilicate glass matrix to protect the environment from radioactivity for hundreds to thousands of years.But glass is a brittle material which the life time can be limited by micro cracks generated during the fabrication.This glass must also resist to leaching by groundwater.It's why it is important to understand the mechanisms of crack propagation in a corrosive environment.The aim of this study is the comprehension of how the toughness is affected by the structural changes on simplified borosilicate glasses under irradiation and variation of the chemical composition of the glasses.Simplified borosilicate glasses are irradiated to simulate alpha and beta decays using He2+ ions and electrons.The subcritical stress corrosion fracture properties of glasses are studied using DCDC samples which permit fracture growth in this regime.The experimental measurements of the crack propagation velocities as a function of the applied stress intensity factor is presented as a v=f(KI) curves.To understand how structural modifications are linked to failure mechanisms RAMAN.NMR and EPR spectra are investigated.