Study of concrete radiation ageing

Abstract

Concrete is a durable material which is a vital part of engineering barrier for radioactive waste disposal. In many concepts of low and intermediate level waste (e.g. the French concept) and in some cases even of high level waste, concrete is planned to be used for construction of containers carrying the primary packages of the immobilized waste. Therefore, it is needed to understand the effect of gamma irradiation on concrete with respect to its durability. A joint experimental program of Czech and French research organizations CVR and CEA respectively was started in order to study the changes in the properties of cementitious composites after their exposition to gamma irradiation. Samples of cement mortars, manufactured in CVR, were divided into two sets, each of them irradiated and characterized with both CVR and CEA facilities. Samples tested in CVR were exposed to cumulative doses of 1.6 to 1.8 et61655;106 Gy with doses from 0.5 to 4.5 kGy/h, while samples in Saclay were exposed to cumulative doses of 0.72 to 3.1et61655;106 Gy with doses 0.6, 1.6 and 2.6 kGy/h, respectively. Mechanical properties of irradiated mortars were then defined by ultrasonic measurement to obtain changes in Young modulus of elasticity and by classical loading to obtain changes of flexural and compressive strength. A comparison with non-irradiated samples maintained in same environment was done. Moreover, investigation of microscopic changes in the concrete structure was executed by scanning electron microscope.Comparison of all the results can be seen in the paper.