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Calcium Phosphate: A Potential Host for Halide Contaminated Plutonium Wastes

Published online by Cambridge University Press:  01 February 2011

Brian L. Metcalfe ,
Ian W. Donald ,
Shirley K. Fong ,
Lee A. Gerrard ,
Denis M. Strachan  and
Randall D Scheele
Brian L. Metcalfe
Affiliation:
brian.metcalfe@awe.co.uk, AWE plc, MSRD, Reading, United Kingdom
Ian W. Donald
Affiliation:
ian.donald@awe.co.uk, AWE plc, MSRD, Reading, United Kingdom
Shirley K. Fong
Affiliation:
shirly.fong@awe.co.uk, AWE plc, MSRD, Reading, United Kingdom
Lee A. Gerrard
Affiliation:
lee.gerrard@awe.co.uk, AWE plc, MSRD, Reading, United Kingdom
Denis M. Strachan
Affiliation:
denis.strachan@pnl.gov, PNNL, Richland, Washington, United States
Randall D Scheele
Affiliation:
randall.scheele@pnl.gov, PNNL, Richland, Washington, United States
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Abstract

The presence of significant quantities of fluoride and chloride in four types of legacy wastes from plutonium pyrochemical reprocessing required the development of a new wasteform which could adequately immobilize the halides in addition to the Pu and Am. Using a simulant chloride-based waste (Type I waste) and Sm as the surrogate for the Pu3+ and Am3+ present in the waste, AWE developed a process which utilised Ca3(PO4)2 as the host material. The waste was successfully incorporated into two crystalline phases, chlorapatite, [Ca5(PO4)3Cl], and spodiosite, [Ca2(PO4)Cl]. Radioactive studies performed at PNNL with 239Pu and 241Am confirmed the process. A slightly modified version of the process in which CaHPO4 was used as the host was successful in immobilizing a more complex multi-cation oxide–based waste (Type II) which contained significant concentrations of Cl and F in addition to 239Pu and 241Am. This waste resulted in the formation of cation-doped whitlockite, Ca3-xMgx(PO4)2, β-calcium phosphate, β-Ca2P2O7 and chlor-fluorapatite rather than the chlorapatite and spodiosite formed with Type I waste.

Keywords

actinideceramicwaste management
Type
Research Article
Information
MRS Online Proceedings Library (OPL) , Volume 1124: Symposium Q – Scientific Basis for Nuclear Waste Management XXXII , 2008 , 1124-Q04-02
Copyright
Copyright © Materials Research Society 2009

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References

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