PNNL

Abstract

To ensure the safe disposal of radioiodine-containing nuclear wastes a durable iodine waste form (IWF) is required. The durability of IWFs will be used to define a radioiodine release source term in performance assessment modeling of disposal sites or repositories. A conceptional corrosion release model (CCRM) is required to generate the source term from IWF. The development of a CCRM that can be universally applied needs “apples to apples” inputs on the corrosion performance of candidate IWF. Many IWF have been developed and evaluated for durability using a wide range of test methods, making a direct comparison difficult. This challenge is highlighted in this work through a review of available IWF corrosion data. To facilitate the move toward a common dataset to support CCRM development a semi-dynamic leach test suite was demonstrated using a range of IWF types (e.g. sodalites, zeolites, glassy composite materials, apatites, tellurite glass, and aerogels), providing a true “apples to apples” comparison. The study highlighted clear differences in corrosion resistance between different IWF types and similar IWF types prepared using different processing methods. The lowest release of iodine was measured for a tellurite glass. This test suite is suggested for future studies to generate comparable durability data to support CCRM development.