CHEMICAL BEHAVIOR OF AQUEOUS IODINE AT THE FORSMARK BOILING WATER-REACTOR NUCLEAR-POWER-PLANTS

Characterization of iodine on-line using mixer-settlers has been perfo rmed in reactor water reactor water cleanup (RWCU) effluent, and conde nsate at the three boiling water reactor (BWR) nuclear power plants (F 1, F2, and F3 at Forsmark, Sweden. Characterization of reactor Mater i odine has also been performed following reactor shutdown at F3. The do minating species in reactor water and condensate was iodide; the rest being essentially iodate. In RWCU effluent, the major species was ioda te. Iodine isotopic ratios showed that iodate was delayed when passing the RWCU system. Formation of organic iodides in the RWCU system was not significant. No changes in the iodine species composition in the r eactor water could be observed directly following reactor shutdown: ho wever, iodide was with time slowly converted to iodate by radiation-in duced oxidation. In reactor water <1% and in condensate and RWCU efflu ent up to 3% of the total iodine existed in the organic form. Organic iodides in the condensate were older than other iodine species.