PNNL

Abstract

Radioiodine capture and immobilization is not only important to consider during the operation of reactors (i.e., I-131) or nuclear fuel reprocessing (i.e., I-131 and I-129), but also during disposal of nuclear wastes (i.e., I-129) and during nuclear accidents (i.e., I-131 and I-129). The majority of disposal plans for many I-129-containing waste forms (including spent nuclear fuel), is to store them in underground repositories. Here, iodine can be highly mobile and, given its radiotoxicity, needs to be carefully managed to minimize long-term environmental impacts arising from disposal. Typically, any process that has been used to capture iodine from reprocessing or in a reactor is not suitable for direct disposal, requiring conversion into a wasteform for disposal. The objectives of these materials are to use either chemical immobilization or physical encapsulation to reduce the leaching of iodine by groundwaters. Some of the more recent ideas have been to design capture materials that better align with disposal concepts, making the industrial processing requirements easier. Research on iodine capture materials and wasteforms has been extensive so far and this review will act as both an update on the state of the research since the last time it was comprehensively summarized and an evaluation of the industrial techniques required to create the proposed iodine wasteforms in terms of resulting material chemistry and applicability.