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Modeling of Dissolution of Sluge from Evaporation Lagoons of Isfahan's UCF Plant

Mireskandari, Seyed Mohammad Mahdi | 2014

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  1. Type of Document: M.Sc. Thesis
  2. Language: Farsi
  3. Document No: 45643 (46)
  4. University: Sharif University of Technology
  5. Department: Energy Engineering
  6. Advisor(s): Samadfam, Mohammad; Charkhi, Amir; Otukesh, Mohammad
  7. Abstract:
  8. Uranium conversion process is one of the most important stages in nuclear fuel cycle. The Uranium Conversion Facilities (UFC) of Iran is located in Isfahan. In this plant, the Yellowcake (impure uranium oxide, U3O8) is converted to Uranium hexa-fluoride, UF6. During the process, considerable amounts of uranium-containing liquid waste are generated. This liquid waste was collected in evaporation pools inside the UCF Plant. In the course of time, a thick layer of precipitated salt form in bottom of the pools which are collected and stored in drums inside a building. This solid waste contains uranium at concentration levels much higher than that permitted for land disposal of the waste. Therefore, the extraction of uranium from this solid waste is highly important. In addition to this environmental consideration, the extraction of uranium might be economically feasible.The first stage in extraction of the uranium for the solid waste is dissolution the waste in an appropriate solvent. Considering the nature of the waste, water was chosen as the solvent for dissolution of the waste.In this thesis, the dissolution of the precipitates in a stirred tank was studied and a mathematical model was developed for the dissolution process.The basic parameters involved in the dissolution have been investigated. The impeller speed (rpm) and initial mass of the solid are among the most important parameters in the dissolution of the solids in the impeller tanks. After reviewing different models of solids dissolution, a mathematical model, based on the experimental kinetic data, was presented for the dissolution of the waste. It was found that the dissolution of uranium is a function of impeller speed (2.32 power), tank diameter (2.81 power) and the initial mass of solid (1 power). Finally, it was found that the Power Number is the best dimensionless Number for the scaling up of the impeller-stirred tanks
  9. Keywords:
  10. Waste Management ; Dissolution ; Modeling ; Stirred Tanks ; Scale Up method ; Evaporation Ponds ; Uranium Conversion Facilities (UCF)Plant

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