Release of Radioactive Materials from a Degrading Core (RADECO): RADECO summary report

The deposition of IOx particles on painted concrete samples and the study on iodine desorption from IOx particle deposition was a joint effort between RADECO and CHEMPC projects. The experiments with iodine oxide deposition on painted concrete, showed some release of gaseous iodine. The desorption of iodine was enhanced on newly painted surface. According to these experiments the formation of the organic iodine is very limited. However, some migration of iodine on the surfaces may be possible by sequential revolatilization and re-trapping. Further experiments would be needed at higher temperature, at high humidity and with different representative surfaces such as metals, paints and cable jacket materials. Nitric acid is a principal radiolytic compound produced in large, and its production is another important problem concerning pH of solutions, owing to its chemical properties of being a strong acid and a strong oxidizing agent. The G value was determined for nitric acid formed from air and for the nitric acid formed from the water. G-value calculated of these moist air results is 2.42 parallel experiments gave G-value 2.32. The determination of G-value for NO3 formation of water in radiation gave G-value 0.024. A preliminary experiment to study the influence of painted surface in the nitrate concentration was made by irradiating water with and without painted concrete block. The preliminary results with the 2.6 kGy dose gave 4 times more nitrate into the water than in blank case.