Ageing of a phosphate ceramic used to immobilize chloride-contaminated actinide waste

Journal Article · Tue Mar 31 00:00:00 EDT 2009 · Journal of Nuclear Materials

DOI:https://doi.org/10.1016/j.jnucmat.2008.12.035· OSTI ID:964613

Metcalfe, Brian ^[1]; Donald, Ian W. ^[1]; Fong, Shirley K. ^[1]; Gerrard, Lee A. ^[1]; Strachan, Denis M. ^[2]; Scheele, Randall D. ^[2]

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1. AWE plc, Reading (United Kingdom)
2. Pacific Northwest National Lab. (PNNL), Richland, WA (United States)

At AWE, we have developed a process for the immobilization of ILW waste containing a significant quantity of chloride with Ca₃(PO₄)₂ as the host material. Waste ions are incorporated into two phosphate-based phases, chlorapatite [Ca₅(PO₄)₃Cl] and spodiosite [Ca₂(PO₄)Cl]. Non-active trials performed at AWE with Sm as the actinide surrogate demonstrated the durability of these phases in aqueous solution. Trials of the process, in which actinide-doped materials were used, wer performed at PNNL where the waste form was found to be resistant to aqueous leaching. Initial leach trials conducted on ²³⁹Pu /²⁴¹Am loaded ceramic at 40°C/28 days gave normalized mass losses of 1.2 x 10^-5 g.m^-2 and 2.7 x 10^-3 g.m^-2 for Pu and Cl respectively. In order to assess the response of the phases to radiation-induced damage, accelerated ageing trials were performed on samples in which the ²³9Pu was replaced with ²³⁸Pu. No changes to the crystalline structure of the waste were detected in the XRD patterns after the samples had experienced an α radiation dose of 4 x 10¹⁸ g^-1. Leach trials showed that there was an increase in the P and Ca release rates but no change in the Pu release rate.

• Research Organization: Pacific Northwest National Lab. (PNNL), Richland, WA (United States)
• Sponsoring Organization: USDOE
• DOE Contract Number: AC05-76RL01830
• OSTI ID: 964613
• Report Number(s): PNNL-SA-60519; JNUMAM; 830403000; TRN: US0903878
• Journal Information: Journal of Nuclear Materials, Vol. 385, Issue 2; ISSN 0022-3115
• Publisher: Elsevier
• Country of Publication: United States
• Language: English

Related Subjects

12 MANAGEMENT OF RADIOACTIVE WASTES, AND NON-RADIOACTIVE WASTES FROM NUCLEAR FACILITIES
ACTINIDES
AQUEOUS SOLUTIONS
CERAMICS
CHLORIDES
LEACHING
PHOSPHATES
RADIATION DOSES
WASTE FORMS
WASTES
X-RAY DIFFRACTION
plutonium immobilization
chloride immobilization
radiation-induced damage
waste management