Effect of gamma irradiation on Portland cement: Hydrogen evolution and radiation resistance

• The γ-radiation decomposes the water in cement with the formation of hydrogen. • The kinetics of hydrogen formation follows an exponential law. • OPC is resistant to radiation up to 100 MGy. • At high doses the mechanical strength of OPC is maintained. • OPC can be used for the immobilization of radioactive wastes. Cementitious materials are widely applied as a matrix for the immobilization of low- and intermediate-level radioactive waste. The use of these materials for high-level waste localization requires knowledge of their properties at high irradiation doses. We have studied the gas evolution and changes in the mechanical strength, composition, and structure of ordinary Portland cement (OPC) upon its irradiation up to absorbed doses of ~ 100 MGy. The decomposition of water present in the cement is accompanied by hydrogen evolution. No oxygen formation was detected. The hydrogen accumulation is described by an exponential equation; the limiting gas concentration reached is approximately 2.8 L per 1 kg of cement. The mechanical strength up to absorbed doses of tens of megagrays varies insignificantly. Irradiation with accelerated (8 MeV) electrons exerts virtually the same effect as does γ-irradiation to the same absorbed dose. The structure, composition, and morphology of cement samples remain virtually unchanged up to high absorbed doses.