Influence of calcium to silica ratio on H-2 gas production in calcium silicate hydrate

摘要

Water radiolysis is of particular concern for the conditioning of radioactive waste with cement materials. For safety assessment, water radiolysis issued from pore solution and hydrates must be considered because radiolytic molecular hydrogen H-2 is produced, which is potentially explosive. Calcium silicate hydrate (C-S-H), main hydrates with Portlandite in Portland cements, were synthesized with different C/S ratios at 60% relative humidity. The samples were characterized by X-ray diffraction and thermogravimetric analysis before irradiation. Then, samples were irradiated under gamma-irradiation, and the radiolytic hydrogen production has been quantified. The results show that, in these conditions, the H-2 production in CSH is comparable to the one in bulk water, with primary yield ranging from 0.35 to 0.6 molecule/100eV.