Résumé
The reprocessing of spent nuclear fuel designed for the first generation of nuclear reactors (of the natural uranium-graphite-gas type) has generated some waste with aluminum metal, which need to be stabilized and solidified before their final disposal. Portland cement (PC) is extensively used for the conditioning of low- or intermediate-level radioactive waste. However, its high alkalinity is a seri-ous problem to aluminum stabilization since it leads to strong corrosion of the metal and the release of dihydrogen. Recent work has shown that magnesium phosphate cements may present higher chemical compatibility with aluminum metal as compared to usual calcium silicate cements (e.g., PC). Their main constituents are magnesium oxide (MgO) and potassium dihydrogen phosphate (KH2PO4). Their hydration mainly yields K-struvite (MgKPO4·6H2O), a low-solubility mineral that sets the pore solution pH to a value close to 8 (i.e., within the passivation domain of aluminum). Nonetheless, the understanding of these binders under leaching conditions is limited and thus, there is the need to gain insights into their long-term durability. Therefore, this work focuses on the leaching behavior of mag-nesium phosphate cement pastes by using experimental and modeling approaches.