Development of multibarrier nuclear waste forms

Technical Report · Thu Mar 01 04:00:00 EST 1979

DOI:https://doi.org/10.2172/5627426· OSTI ID:5627426

The multibarrier concept aims to separate the radionuclide-containing inner core material and the environment by the use of coatings and matrices. Two options were developed for the inner core of the multibarrier concept: supercalcine pellets and glass marbles. Supercalcine is a crystalline assemblage of mutually compatible, refractory, and leach-resistant solid solution phases incorporating high-level liquid waste ions. Supercalcine powder is produced by spray calcining the liquid waste stream to which Al/sub 2/O/sub 3/, CaO, SiO/sub 2/, and SrO have been added. Supercalcine pellets are produced by disc pelletizing. The amorphous supercalcine crystallizes into solid solution phases after subsequent heat treatment. Based on the multibarrier processes described, several conclusions can be made: gravity sintering and vacuum casting are both applicable methods for metal matrix encapsulation. The multibarrier concept of glass marbles encapsulated in a vacuum-cast lead alloy provides enhanced inertness at a minimum increase in technological complexity. If it were desirable to develop a crystalline multibarrier waste form, uncoated sintered supercalcine pellets would offer enhanced inertness at a much lower level of technological complexity than glaze- or CVD-coated supercalcine. The 16-inch diameter pelletizer unit has enough capacity to handle the output of a large PNL spray calciner (52.5 kg of calcine/hr) and it can form spray-calcined material into pellets with diameters of 2 mm to 20 mm having strength enough to withstand handling without significant breakage.Chemical vapor deposition coating of supercalcine should be pursued only if a very high level of inertness is required.

• Research Organization: Battelle Pacific Northwest Labs., Richland, WA (USA)
• Sponsoring Organization: USDOE
• DOE Contract Number: EY-76-C-06-1830
• OSTI ID: 5627426
• Report Number(s): PNL-SA-7292
• Country of Publication: United States
• Language: English

Related Subjects

052001* -- Nuclear Fuels-- Waste Processing
12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE WASTES FROM NUCLEAR FACILITIES
CALCINATION
CERAMICS
CHEMICAL REACTIONS
COATINGS
DECOMPOSITION
ENCAPSULATION
GLASS
HIGH-LEVEL RADIOACTIVE WASTES
MANAGEMENT
PHASE TRANSFORMATIONS
PROCESSING
PYROLYSIS
RADIOACTIVE MATERIALS
RADIOACTIVE WASTE PROCESSING
RADIOACTIVE WASTES
SOLIDIFICATION
THERMOCHEMICAL PROCESSES
WASTE MANAGEMENT
WASTE PROCESSING
WASTES