Confinement of airborne radioactivity. Progress report: January--December 1975

Abstract

Efforts are underway at Savannah River Laboratory (SRL) and the Naval Research Laboratory (NRL) to develop new carbonimpregnant formulations suitable for use in nuclear power plants as well as in the SRP system. Emphasis has been placed on carbons derived from domestic raw materials and impregnated with an amine having lower vapor pressure, higher flash point, and lower cost than triethylenediamine (TEDA). Promising results have been obtained with carbons derived from coal, petroleum, wood, and coconut and impregnated with a combination of iodine salts and hexamethylenetetramine (HMTA). Service-aging of several of the HMTA-iodine salt carbons is also being studied. A separate study of the ability of sodium thiosulfate and potassium hydroxide to retain iodine in aqueous solutions in the presence of high-intensity gamma radiation show that concentrations of ~l wt % thiosulfate are required to reduce iodine evolution to less than 1%. A 0.05 wt % addition of potassium hydroxide has about the same effect. These studies revealed that lower concentrations of thiosulfate actually appear to promote evolution of both iodine and an unidentified species of iodine that is capable of penetrating several inches of carbon adsorber. The unidentified iodine compounds are, however, efficiently retained by a HEPA filter. This result suggests that the penetrating iodine may exist in the form of a particulate or aerosol. Iodine 17 CONFINEMENT OF AIRBORNE RADIOACTIVITY