Novel concept for a filtered containment venting system with an ionic liquid to remove organic iodine (1). Proof of concept for organic iodine removal

Ionic liquid (IL) as a chemical adsorbent used in a filtered containment venting system (FCVS) in a nuclear power plant was considered as a new mitigation method for radioactive organic iodine release in the event of a severe accident. In order to demonstrate proof of concept (PoC) for organic iodine removal with the IL, we evaluated the decontamination factor (DF) of the IL for the organic iodine at various temperatures as an index of removal performance. As a removal mechanism for organic iodine with the IL, it was assumed that the anions function to decompose organic halides such as by a Williamson ether synthesis reaction. We evaluated DF for organic iodine using the IL containing thiosulfate ions and while controlling temperature and residence time as changeable parameters. We determined the DF of the IL for the organic iodine was more than 100 in the temperature range from 393 to 433 K and residence time of 0.1 s or longer. The allowable chemical adsorption weight of organic iodine was 5.9 g kg-IL^-1. It was concluded that IL was a possible candidate as an organic iodine adsorbent for a next-generation FCVS. (author)