Preparation of monophasic [NZP] radiophases: Potential host matrices for the immobilization of reprocessed commercial high-level wastes

Conference · Wed Dec 31 04:00:00 EST 1997

OSTI ID:572093

Hawkins, H T; Guthrie, Jr, G D ^[1]; Scheetz, B E ^[2]

---

1. Los Alamos National Lab., NM (United States)
2. Pennsylvania State Univ., University Park, PA (United States). Intercollege Materials Research Lab.

The compositional flexibility of the sodium zirconium phosphate (NaZr{sub 2}(PO{sub 4}){sub 3}) structure has been exploited in the design of monophasic radiophases capable of immobilizing the most common cations associated with reprocessed high-level commercial waste streams. Highly crystalline, monophasic members of the NaZr{sub 2}(PO{sub 4}){sub 3} structural family ([NZP]) have been prepared with conventional processing methods and equipment. These radiophases were tailored to accommodate 10--20 wt% modified PW-4b simulated calcine as single phases isostructural with NaZr{sub 2}(PO{sub 4}){sub 3}. To meet the challenge of designing monophasic materials capable of accommodating the chemical complexity of PW-4b, an ionic substitution scheme based on crystal chemical principles was developed. The radiophases were prepared with inexpensive, inorganic precursors and a solution sol-gel method; these materials were heat treated and/or sintered under a variety of conditions to determine the optimum conditions for single phase [NZP] formation. X-ray powder diffraction provided valuable information that was used to assess the suitability of the ionic substitution model developed in this investigation. The results of this investigation suggest that monophasic [NZP] radiophases capable of accommodating 10--20 wt% modified PW-4b simulated calcine may be continuously processed with conventional ceramic processing methods and equipment. Moreover, the relatively low temperatures involved and the reproducibility of the process make [NZP] radiophases economically attractive hosts for radioactive and heavy metal industrial wastes.

• Sponsoring Organization: USDOE, Washington, DC (United States)
• OSTI ID: 572093
• Report Number(s): CONF-961202--
• Country of Publication: United States
• Language: English

Related Subjects

05 NUCLEAR FUELS
36 MATERIALS SCIENCE
CRYSTAL STRUCTURE
HIGH-LEVEL RADIOACTIVE WASTES
MATRIX MATERIALS
SODIUM PHOSPHATES
SOL-GEL PROCESS
WASTE FORMS
X-RAY DIFFRACTION
ZIRCONIUM PHOSPHATES