Excess Pu disposition in zirconolite-rich Synroc containing nepheline
Conference
·
OSTI ID:264410
- ANSTO, Menai, New South Wales (Australia)
- Lawrence Livermore Nation Lab., CA (United States)
A titanate Synroc ceramic for the immobilization of Pu-bearing waste was designed to consist of 70 wt% zirconolite (CaZrTi{sub 2}O{sub 7}) + 15 wt% nepheline (NaAlSiO{sub 4}) + 15 wt% rutile (TiO{sub 2}). It contained 10 wt% of Pu plus 6 wt% of Gd as a neutron poison. The material was made by the standard sol-gel route, using a mixture of alkoxides and nitrates, followed by stir-drying and calcination. It was fabricated by hot-pressing at 1,150--1,250 C/20 MPa for 2 hours in a collapsible metal bellows. Though zirconolite was the majority phase, {approximately} 20 wt% of perovskite also formed. Some of the Na, intended for nepheline, partitioned into the titanate phases. 84-day differential total leach rates of Pu were in the order of 10{sup {minus}5} g/m{sup 2}/d at 90 and 200 C. Companion ceramics using molar substitution of Ce for Pu confirmed the idea that Ce is a good simulant of Pu from a solid state chemical view, but that there are limitations in terms of leach rate parallels.
- OSTI ID:
- 264410
- Report Number(s):
- CONF-951155--; ISBN 1-55899-315-0
- Country of Publication:
- United States
- Language:
- English
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