Institute of Nuclear Energy Research

Tzeng-Ming Liu

Ching-Tsuen Huang

Tsye-Shing Lee

Jiing-Guang Tyen

Wen-Chao Lai

Da-Luh Lu

A method for processing spent ion-exchange resins is provided by reducing the volume of the spent ion-exchange resins through a wet oxidation process and solidifying the residual wet oxidation slurry and the waste solution with high efficiency. The method comprises of using barium hydroxide as a neutralization agent to adjust pH of the reaction solution so as to drive away ammonia from the solution, and as a conversion agent to convert sulfuric acid and sulfate obtained in the reaction into barium sulfate. The process can solidify the wet oxidation residue slurry and waste solution with high efficiency.

Method for processing spent ion-exchange resins

A method for removing at least one of chromate and other oxy-metal ions from liquid solutions includes contacting the liquid solution with solid barium compounds as adsorbents so that the at least one of chromate and other oxy-metal ions in liquid solution are subject to an exchange reaction with the anion of solid barium compounds to produce products including at least one of solid barium chromate and oxy-metal barium compounds and are removed from the liquid solution by a liquid-solid separation operation. A method for stabilizing at least one of chromate and other oxy-metal ions that are present in liquid or sludge wastes includes mixing the liquid or sludge wastes with barium compounds in solid form, so that the at least one of chromate and oxy-metal ions are immobilized in a solidified body after curing of the mixture.

Method for liquid chromate ion and oxy-metal ions removal and stabilization

This invention discloses a method for the co-solidification of low-level radioactive wet wastes of BWR nuclear power plants, including concentrate waste, spent ion exchange resins and sludge wastes etc., with very high volume efficiency. In this invention, for promoting the stability of the solidified waste, sodium sulfate in the concentrate solution is converted to sodium hydroxide and barium sulfate by reacting with barium hydroxide. The conversion product barium sulfate possessing high density and stability is insoluble and used as a fine aggregate material in the solidified waste. Sodium hydroxide is used to stabilize ion exchange resins and to form a highly water-durable solidified waste form with silicates and phosphates in the solidification agent mixture. The solidification agent used in this invention is a formulated powder mixture completely made from inorganic materials. Therefore, there is no aging problem of the solidified waste. In this invention, the waste loading of the solidified waste is highly increased due to the conversion of sodium sulfate and the co-solidification of wastes. Thus, the solidification volume efficiency of the present invention is about three times of the solidification of the waste separately.

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Chung Li, Taiwan

Tzeng-Ming Liu