Destruction of Mixed Liquid Waste
Development of Technology of Catalytic Fluidized Bed Destruction of Mixed Liquid Organic Wastes from Radiochemical and Chemical-Metallurgical Plants
Tech Area / Field
- ENV-WPC/Water Pollution and Control/Environment
8 Project completed
Senior Project Manager
Boreskov Institute of Catalysis, Russia, Novosibirsk reg., Akademgorodok
- VNIPIET (Novosibirsk Branch), Russia, Novosibirsk reg., Novosibirsk\nSiberian Chemical Combine, Russia, Tomsk reg., Seversk\nNovosibirsk Chemical Concentrates Plant, Russia, Novosibirsk reg., Novosibirsk
- Lawrence Livermore National Laboratory, USA, CA, Livermore\nPacific Northwest National Laboratory, USA, WA, Richland
Project summaryThe objective of this project is development and demonstration of a new, environmentally safe technology of destruction of mixed liquid organic wastes of radiochemical and chemical-metallurgical plants, containing radionuclides of uranium, plutonium and fission products, by total oxidation of waste organic components in a fluidized catalyst bed and transition of radionuclides to compact solid phase for future processing or disposal. The final result of the work will be creation of a prototype demonstration plant with a capacity of 50 t per year at Siberian Chemical Complex in Seversk (former Tomsk-7).
The principal participants in this project are the Boreskov Institute of Catalysis (BIC), Siberian Chemical Complex (SCC), Research and Design Institute of Minatom NGPII VNIPIET, and the Novosibirsk Plant of Chemical Concentrates (NPCC).
At present mixed liquid organic wastes are kept in tanks at nuclear material processing plants representing a potential threat to the environment because of the combination of inflammability, explosiveness, toxicity and radioactivity. Development of safe and environmentally clean technology for destruction of these wastes is an urgent problem. At Siberian Chemical Complex there are three main sources of such wastes:
1. Traditional production
2. Processing of spent nuclear fuel
3. Reprocessing of weapons-grade uranium to uranium with low enrichment
Due to accumulation of mixed organic wastes and the absence of reliable and safe technology for their treatment the solution of the problem of organic mixed waste destruction is very urgent for SCC.
The method of waste thermal combustion used in some cases cannot be considered sufficiently safe because it leads to the formation of secondary pollutants (nitrogen oxides, CO, polycyclic aromatic hydrocarbons) and generation of sub-micron radioactive particles which may be emitted into the atmosphere with combustion off-gases. Other drawbacks of this method are formation of secondary radioactive waste stream, e.g., deteriorated refractories and production of high temperature refractory type plutonium dioxide which is not readily soluble for further treatment in actinide recovery process. Open flame methods require multi-stage (7 and more) and complicated system of gas purification
In the frame of the ISTC project 110-94 we have developed a technology of environmentally safe treatment of mixed organic wastes containing natural uranium formed in fuel rods production by low-temperature flameless combustion in a catalyst fluidized bed. At present the construction of prototype demonstration plant for mixed waste treatment is in progress at NPCC. In the development of technology of the treatment of mixed organic wastes of radiochemical and chemical-metallurgical plants, specific nature of these wastes should be taken into account. These wastes contain enriched uranium (up to 90 %) and isotopes of plutonium (Pu239, Pu240, Pu241, Pu242) and fission products. In comparison with mixed wastes formed in fuel rod production, the treatment of such wastes must meet special requirements due to higher specific radioactivity and criticality factors, e.g. the provision of reliable biologic protection and three-zone arrangement of equipment.
In this project, the technological scheme, equipment and catalysts for the destruction of mixed organic wastes formed at radiochemical and chemical-metallurgical plants will be developed. These wastes have complex composition and consist of industrial and vacuum pump oils, used extractants and solvents (among them Cl- and P-containing compounds) with admixtures of U, Pu and their fission products.
Siberian Chemical Complex will make an inventory and study the composition and properties of organic wastes, prepare Technical Task Plans (TTP) for research and development work, and deliver inactive model mixtures and waste components to NGPII and NPCC for research work on organic waste treatment at existing bench setups. BIC will develop and prepare combustion catalysts and together with NGPII and NPCC will study processes of waste destruction in these setups. These studies will furnish new data on catalytic combustion of Cl- and P-containing compounds necessary for the preparation of novel catalysts stable in aggressive reaction media and process optimization. NGPII VNIPIET will develop an efficient gas cleaning system after the catalytic reactor with the application of new technical approaches ensuring the necessary purity of gaseous emissions. Based on the results obtained, NGPII VNIPIET with participation of BIC and NGPII VNIPIET will prepare a TTP for a plant design, according to which NGPII VNIPIET and SCC will make construction documentation for a demonstration plant with a capacity of 50 tons of wastes per year.
BIC will oversee the preparation of catalysts for use in the demonstration plant. The plant will be constructed at the Siberian Chemical Complex. Tests of the plant will be conducted with the participation of all Russian and American project participants. The resulting experience will assist in the introduction of the improved destruction process at other nuclear material processing plants in Russia. The information will also be useful to waste-processing specialists in the USA.
The participation of foreign collaborators in this program will consist in consulting on the implementation of fluidized bed oxidation technology with low level combustible wastes, identification and characterization of wastes in these general categories, joint testing of catalysts, and general assistance during the pilot plant startup.
The program proposed would allow a number of weapons scientists, engineers and technicians in Russia to redirect their talents to the solution of international environmental problems and to solve the particular problem of treating the mixed wastes accumulated at nuclear material processing plants.
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