A variety of intermediate- and low-level liquid and solid wastes are produced from reactor production of 99Mo using UAl alloy or UO2 targets and in principle can be collectively or individually converted into waste forms. At ANSTO, we have legacy acidic uranyl-nitrate-rich intermediate level waste (ILW) from the latter, and an alkaline liquid ILW, a U-rich filter cake, plus a shorter lived liquid stream that rapidly decays to low-level waste (LLW) standards, from the former. The options considered consist of cementitious products, glasses, glass-ceramics, or ceramics produced by vitrification or hot isostatic pressing for intermediate-level wastes. This paper discusses the progress in waste form development and processing to treat ANSTO’s ILW streams arising from 99Mo. The various waste forms and the reason for the process option chosen will be reviewed. We also address the concerns over adapting our chosen process for use in a hot-cell environment. 1. Introduction 99Mo is produced in several countries; notably Belgium, Netherlands, Canada, and South Africa produce > 2,500 6dCi. (This refers to the number of curies of 99Mo left 6 days after shipping from a production facility and is typically used during operation in allocating and pricing the shipment.) There are also smaller producers (300–1500？6dCi) in France, Russia, Czech Republic, Poland, Australia, and Argentina [1]. Wastes arising from 99Mo production using nuclear reactor irradiation of enriched U-bearing targets range from ILW to LLW in both liquid and solid forms, according to current International Atomic Energy (IAEA) Classifications [2]. In 99Mo production, the higher activity wastes would typically be classified as ILW, even after decaying for a few years. Traditionally [3], the boundary between ILW and high-level waste (HLW) was set at a heat output from the decay of radioisotopes of 2？kW/m3 and the boundary between ILW and LLW was that at which shielding was required (contact dose of 2？mSv/hr). Both HLW and ILW require shielding; however, ILW due to its lower heat output does not require controlled cooling during storage. In the updated version of the IAEA Classification System [2], the heat output has been omitted. This is because the new standard for classification and treatment is more closely related to the disposition options and the heat output limits for a waste package should now be linked to the safety cases for the storage/disposal facility. Other methods of classification exist; for example, the British in determining the amount of waste to be returned to customers from its
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