Production of H^sub 2^ by water radiolysis in cement paste under electron irradiation: A joint experimental and theoretical study

Long-term confinement of nuclear waste is one of the main challenges faced by the nuclear industry. Fission products such as 90Sr and 137Cs, both β- emitters known to induce serious health hazards, represent the largest fraction of nuclear waste. Cement is a good candidate to store them, provided it can resist the effects of irradiation over time. Here, we have investigated the effects of β- decay on cement by performing electron irradiation experiments on different samples. We show that H2 production in cement, the main effect of water radiolysis, depends strongly on composition and relative humidity. First-principles calculations indicate that the water-rich interlayer regions with Ca2+ ions act as electron traps that promote the formation of H2. They also show that holes localize in water-rich regions in low Ca content samples and are then able to participate in H2 production. This work provides new understanding of radiolysis effects in cements.