Abstract Since the end of the 1970s, Synroc at the Australian Nuclear Science and Technology Organisation (ANSTO) has evolved from a focus on titanate ceramics directed at PUREX waste to a platform waste treatment technology to fabricate tailored glass–ceramic and ceramic waste forms for different types of actinide, high- and intermediate level wastes. The particular emphasis for Synroc is on wastes which are problematic for glass matrices or existing vitrification process technologies. In particular, nuclear wastes containing actinides, notably plutonium, pose a unique set of requirements for a waste form, which Synroc ceramic and glass-ceramic waste forms can be tailored to meet. Key aspects to waste form design include maximising the waste loading, producing a chemically durable product, maintaining flexibility to accommodate waste variations, a proliferation resistance to prevent theft and diversion, and appropriate process technology to produce waste forms that meet requirements for actinide waste streams. Synroc waste forms incorporate the actinides within mineral phases, producing products which are much more durable in water than baseline borosilicate glasses. Further, Synroc waste forms can incorporate neutron absorbers and 238U which provide criticality control both during processing and whilst within the repository. Synroc waste forms offer proliferation resistance advantages over baseline borosilicate glasses as it is much more difficult to retrieve the actinide and they can reduce the radiation dose to workers compared to borosilicate glasses. Major research and development into Synroc at ANSTO over the past 40 years has included the development of waste forms for excess weapons plutonium immobilization in collaboration with the US and for impure plutonium residues in collaboration with the UK, as examples. With a waste loading of 40–50 wt.%, Synroc would also be considered a strong candidate as an engineered waste form for used nuclear fuel and highly enriched uranium-rich wastes.

Synroc tailored waste forms for actinide immobilization

https://digital.library.unt.edu/ark:/67531/metadc845598/m2/1/high_res_d/1024475.pdf

Integration of facility modeling capabilities for nuclear nonproliferation analysis

Application of the extended Pitzer equation to nuclear fuel reprocessing

The chemical reprocessing of discharged nuclear reactor fuel allows the large quantities of energy found in uranium and plutonium to be recycled back to the reactors while separating out the fission products as a waste stream. The PUREX process, used to recycle nuclear reactor fuel, was developed as part of the U.S. defense program. This process is described. The world's principal fuel reprocessing centers are located in the U.K., France, and Japan. Smaller units are operating in India. No chemical reprocessing takes place in the United States.



Chemical reprocessing involves fuel decladding, mechanically cutting or shearing the tubing in which the nuclear fuel is encapsulated, and fuel dissolution, prior to chemical separation of the nonradioactive materials, the fission products, and the unburned fuel. Several types of countercurrent solvent extraction equipment are used to separate the useful components. The uranium and plutonium products are converted to oxides from which recycle fuel is fabricated. The wastes are safely stored for future disposal.


Keywords:

Separation processing;
Nuclear reactors;
Reprocessing strategy;
Fuel characteristics;
Product conversion;
Waste handling;
Fuel shear;
Liquid waste storage tanks;
Liquid-liquid contactors

J. C. Hall

Papers

Nuclear Reactors, Chemical Reprocessing