Interactions of I_2 and CH_3I with reactive metals under BWR severe-accident conditions

摘要

I_2 released from fuel in the event of a severe nuclear reactor accident has the ability to deposit on surfaces in the containment building. This study has focused on the reactions of I_2 with reactive metals available in the containment. The experiments have been performed under conditions similar to those in a boiling water reactor at an accident situation. Copper, zinc and aluminium showed extensive uptake of gaseous I_2 under humid conditions. Reaction rates were determined at 25, 50 and 70 ℃ and could be used for quantifying the effect of reactions between gaseous I_2 and copper, zinc and aluminium. Experiments with the metals placed in water showed lower I_2 uptake. Zinc iodide and aluminium iodide rapidly dissolves in water and no uptake of I_2 on these surfaces could be verified. Copper iodide has low solubility and I_2 was adsorbed on the surface. Experiments performed with reactive metals and methyl iodide showed a minor uptake of methyl iodide on zinc and aluminium in the gas phase for temperatures up to 80℃. A continuous uptake of methyl iodide on copper was measured at 80 ℃.