Kenneth J. Bateman

A Description of the Ceramic Waste Form Production Process from the Demonstration Phase of the Electrometallurgical Treatment of EBR-II Spent Fuel

Abstract The electrometallurgical treatment (EMT) process has been designed and developed for stabilizing sodium-bonded, metallic fuel into two high-level waste forms. This process has recently been successfully demonstrated with irradiated EBR-II fuel at Argonne National Laboratory-West. Part of the EMT process is to immobilize fission-product-bearing waste salt, which results from electrorefining, in a ceramic waste form—a glass-bonded sodalite. The sodalite is formed by hot isostatically pressing salt-loaded zeolite at temperatures up to 850°C and pressures up to 100 MPa. The specific unit operations that comprise ceramic waste production include steps for salt grinding, zeolite drying, blending salt and zeolite and glass frit in a v-blender, and consolidating the powders in a hot isostatic press. The results of testing these unit operations with irradiated salt from the EMT demonstration are summarized and include some preliminary characterization of the final irradiated ceramic waste form created by this process.

Characterization of a ceramic waste form encapsulating radioactive electrorefiner salt

Argonne National Laboratory has developed a ceramic waste form to immobilize radioactive waste salt produced during the electrometallurgical treatment of spent fuel. This study presents the first results from electron microscopy and durability testing of a ceramic waste form produced from that radioactive electrorefiner salt. The waste form consists of two primary phases: sodalite and glass. The sodalite phase appears to incorporate most of the alkali and alkaline earth fission products. Other fission products (rare earths and yttrium) tend to form a separate phase and are frequently associated with the actinides, which form mixed oxides. Seven-day leach test results are also presented.

Development of a ceramic waste form for high-level waste disposal.

A ceramic waste form is being developed by Argonne National Laboratory (ANL) as part of the demonstration of the electrometallurgical treatment of spent nuclear fuel. The halide, alkaline earth, alkali, transuranic, and rare earth fission products are stabilized in zeolite which is combined with glass and processed in a hot isostatic press (HIP) to form a ceramic composite. The mineral sodalite is formed in the HIP from the zeolite precursor. The process, from starting materials to final product, is relatively simple. An overview of the processing operations is given. The metrics that have been developed to measure the success or completion of processing operations are developed and discussed. The impact of variability in processing metrics on the durability of the final product is presented.

Modeling Solidification-Induced Stress in Ceramic Waste Forms Containing Nuclear Wastes

Abstract The goal of this work is to produce a ceramic waste form that permanently occludes radioactive waste. This is accomplished by absorbing radioactive salts into zeolite, mixing with glass frit, heating to a molten state at 915°C to form a sodalite glass matrix, and solidifying for long-term storage. Less long-term leaching is expected if the solidifying cooling rate does not cause cracking. In addition to thermal stress, this paper proposes a mathematical model for the stress formed during solidification, which is very large for fast cooling rates during solidification and can cause severe cracking. A solidifying glass or ceramic cylinder forms a dome on the cylinder top end. The temperature distribution during solidification causes the solidification stress and the dome resulting in an axial length deficit. The axial stress, determined by the length deficit, remains when the solid is at room temperature with the outer region in compression and the inner region in tension. Large tensions will cause cracking of the specimen. The temperature deficit, derived by dividing the length deficit by the coefficient of thermal expansion, allows solidification stress theory to be extended to the circumferential stress. This paper derives the solidification stress model, gives examples, explains how to induce beneficial stresses, and compares theory to experimental data.

Characterization of composite ceramic high level waste forms.

Argonne National Laboratory has developed a composite ceramic waste form for the disposition of high level radioactive waste produced during electrometallurgical conditioning of spent nuclear fuel. The electrorefiner LiCl/KCl eutectic salt, containing fission products and transuranics in the chloride form, is contacted with a zeolite material which removes the fission products from the salt. After salt contact, the zeolite is mixed with a glass binder. The zeolite/glass mixture is then hot isostatic pressed (HIPed) to produce the composite ceramic waste form. The ceramic waste form provides a durable medium that is well suited to incorporate fission products and transuranics in the chloride form. Presented are preliminary results of the process qualification and characterization studies, which include chemical and physical measurements and product durability testing, of the ceramic waste form.

Hot isostatic pressing of ceramic waste from spent nuclear fuel.

Argonne National Laboratory has developed a process to immobilize waste salt containing fission products, uranium, and transuranic elements as chlorides in a glass-bonded ceramic waste form. This salt was generated in the electrorefining operation used in electrometallurgical treatment of spent Experimental Breeder Reactor-II fuel. The ceramic waste process culminated with a hot isostatic pressing operation. This paper reviews the installation and operation of a hot isostatic press in a radioactive environment. Processing conditions for the hot isostatic press are presented for non-irradiated material and irradiated material. Sufficient testing was performed to demonstrate that a hot isostatic press could be used as the final step of the processing of ceramic waste for the electrometallurgical spent fuel treatment process.