A non-isothermal reactive transport model of the long-term geochemical evolution at the disposal cell scale in a HLW repository in granite

The assessment of the long-term performance engineered barrier systems high-level radioactive waste (HLW) repositories requires use reactive transport models. Here a non-isothermal model geochemical evolution HLW disposal cell in granitic host rock is presented. includes vitrified (40 cm diameter), carbon-steel canister (5 thick), saturated FEBEX bentonite buffer (75 thick) and reference rock. accounts for thermal transient stage assumes generalized steel corrosion under anaerobic conditions with rate equal to 1.41 m/y. Canister failure assumed occur when remaining thickness 3.5 at t = 25,000 years. caused an increase pH. computed pH just before (t years) was 9.25 ranged from 7.82 bentonite. Magnetite, main product, precipitated especially canister. magnetite precipitation band ≈ 1 cm. Siderite both sides canister/bentonite interface. front penetrated >1 into Nuclear glass started dissolving after > years). concentration dissolved silica increased inner part until 30,000 years decreased outer due out diffusion This diffusive flux greenalite glass/canister interfaces. end simulation 50,000 7.93 7.89 glass, 8.66 7.87 8.6 Magnetite while there carbon corrode. Once fully corroded, redissolved near Greenalite bentonite, interface siderite results should be useful barriers rocks.