Storing strong spent ionizing-radiation sources in metal matrices

Abstract

The sources are stored by discharging them from the containers into special underground stores, with a volume of 200 dm 3 at a depth of 6 m. The loading channel is a curved tube, which protects the direct radiation. A store is designed to receive 1.184 • i0 Is Bq (50 kg-eq Ra) at a maximum permissible temperature of 503 K. Such stores have been in use at the Moscow Radon Production Cooperative for over 20 years. Observations on them have shown that storing sources in these underground spaces in piles does not provide satisfactory safety [2]. Free dropping means that the sources accumulate at the bottom, with many of the radioactive carriers concentrated in a small volume, which means that the radiation and thermal loads on the materials are elevated there. For example, the radiation dose rates in the stores attain 1.419 A/kg (5.5 • 103 R/sec) [2]. Water condensing on the cold walls of the loading pipe flows into the store and increases the corrosion. Radiolysis gives rise to hydrogen concentrations representing an explosion hazard. Also, the rising hot air flows can transport hot aerosol particles into the environment, which represent a considerable radiological hazard.