Cementing methods is mainly used for low and intermediate level radioactive waste. Currently, cement stone is almost never considered as a matrix for immobilizing high level waste due to probable low durability of as well as to radiolysis cement hydrates and pore-water under high radiation dose.
The objective of this report is the assessment of cement compounds affected by high radiation dose typical of high level activity waste. Cement compound samples of different water-cement ratio were affected by up to 108 Gy radiation dose during the research.
Irradiated cement samples were observed to examine changes in regulated properties. Gas emission from cement samples and crystal phase structural changes were also assessed during the research. The research of structural changes of cement stone due to ionized radiation were done by the following methods: X-ray phase, Petrographic, Electron micrograph, Electron- microscopic analyses.
Comparative assessment of the samples before and after irradiation shows that cement compounds meet regulated requirements of final radioactive product.
Compressive strength was considered as a criterion. The samples subjected to hardening for 28 days have from 4 to 8 times more compressive strength than the required 5 MPa. The research proves that irradiated compounds have the same durability after frost resistance and emersion tests.
As a result of the experiment, the concentration of hydrogen emitted from cement compounds was also measured. The quantity of emitted hydrogen from higher water-cement ratio is a bit higher due to higher water level. The research verifies that the highest level of hydrogen is not higher than 10-3 mol/ (per sample).
The studies of structural and morphological characteristics of cement samples by the above mentioned methods show that structural and phase changes in the samples are not revealed.
The results of the research show that examined cement compounds withstand radiation dose up to 108 Gy.