Modular Testing of Dinitrogen Oxide (Nitrogen Hemioxide) Catalytic Decomposition Technology for Off-Gas Cleanup Systems for Brest Spent Nuclear Nitride Fuel Reprocessing

Abstract

Dinitrogen oxide N₂O (nitrogen hemioxide) is one of the harmful components of the off-gases during the reprocessing of spent nitride fuel. It enters the gas phase during the dissolution of nitride fuel in nitric acid and denitration of high-activity raffinate or the bottom solution from the evaporation of intermediate-level wastes. The preferred method of neutralizing it is high-temperature catalytic decomposition. Compositions based on γ-aluminum oxide coated with catalysts were found previously. One of the compositions was checked on a semi-industrial setup. The efficiency of N₂O decomposition was studied as a function of temperature. It was established that almost complete decomposition occurs at 465–480°C. The specific rate of N₂O decomposition at 425–480°C was found as a function of the initial concentration. It is shown that for constant initial concentration of N₂O the specific decomposition rate is almost the same in the investigated temperature interval.