Dose, dose rate and irradiation temperature effects in β-irradiated simplified nuclear waste glasses by EPR spectroscopy

The influence of dose, dose rate and irradiation or annealing temperature on the formation of paramagnetic centers has been investigated by electron paramagnetic resonance (EPR) spectroscopy on a series of β-irradiated 4-, 5- and 6-oxide glasses in order to study the use of external β-irradiation relative to simulate actual conditions during the storage of nuclear waste glasses. An unusual saturation of defect concentration occurs above 104 Gy. There is no dose rate dependence for the irradiation in a range between 2×103 and 2×104 Gy/s. The increase of irradiation temperature leads to an increase of Zr3+, a decrease of Fe3+ concentration, the formation of magnetic clusters and a strong decrease in the total concentration of paramagnetic defects. In addition, annealing and irradiation temperatures do not produce the same effects on the concentration of the various defects.