International audienceSeveral strategies propose to store and confine High level Radioactive Waste in a deep geological disposaI. Andra (French National Radioactive Waste Management Agency) suggests a multi barrier system including the glass canister, a carbon steel overpack and a low permeability clay host rock to prevent borosilicate glass alteration and to limit migration of radionuclides released under the action of water. However after thousand years and resaturation of clay, water will corrode the carbon steel overpack causing the release iron ions and precipitation of iron carbonates as corrosion products. The glass matrix will alter through glass hydrolysis and release silicon in solution. Thus, neoformed Fe-Si-O phases can precipit...