Titanate Ceramic Matrices for Alumina-Rich Wastes
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7LWDQDWH&HUDPLF0DWULFHVIRU$OXPLQD5LFK:DVWHV Bruce D. Begg, Eric R. Vance, Huijun Li, Terry McLeod, Nicholas Scales, and Mugdha Bhati Materials and Engineering Science, Australian Nuclear Science and Technology Organisation New Illawarra Road, Menai, NSW, 2234, Australia $%675$&7 In the early 1980s a synroc variant, SYNROC-D, was developed for immobilisation of highlevel defence waste stored at the Savannah River Plant, USA. A key phase in the immobilisation matrix was spinel, used to immobilise the large proportion of iron and alumina in the waste. Here we examine the feasibility of this approach for other alumina-rich wastes, not necessarily containing iron, derived from the dissolution of aluminium fuel cladding. The advantages of using a magnesia spinel, as opposed to hercynite (FeAl2O4), as the primary alumina-bearing phase are discussed in terms of an increase in waste loading and process flexibility. Two options for sodium incorporation, glass and the titanate phase freudenbergite, are considered. ,1752'8&7,21 In the early 1980s a synroc variant, SYNROC-D, was developed for immobilisation of highlevel defence waste stored at the Savannah River Plant, USA [1-3]. This waste was rich in alumina and contained a considerable amount of iron along with ~3% fission products plus actinides and a smaller proportion of sodium. Zeolites were also to be included in the waste composition for immobilisation. Sodium hydroxide was a common additive used to neutralise the high-level waste after reprocessing. The design philosophy for SYNROC-D was to immobilise the large proportion of iron and alumina in a hercynite spinel (FeAl2O4). Zirconolite and perovskite were the designated hosts for rare earths and actinides, with nepheline being the host phase for sodium and cesium [1]. A subsequent variation included hollandite as the cesium host phase. Here we examine the feasibility of this approach for other alumina-rich reprocessed highlevel wastes, not necessarily containing iron, derived from the dissolution of aluminium fuel cladding. The potential for these wastes to also contain sodium (
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