Decomposition of Nitric Oxide and Nitrogen Dioxide by the Impact of Fission Fragments of Uranium-235

Abstract

A study was made of the decomposition of nitric oxide and nitrogen dioxide using the fission recoil energy of 5 mg of uranium‐235 oxide powder. The irradiations were conducted in a 23‐cc quartz vessel, at a flux of 3×10¹² neutrons | cm² second, and at a temperature of 70°C in the Brookhaven National Laboratory Reactor. With a dose of 2×10⁹ r, the over‐all G_NO is 9.5±1.0, using a radiation intensity of 1.0×10⁷ r | min, a filling pressure of 500 mm at 21°C. With a dose of 10⁸ r, the G_NO is 13.8±1.4. Since three additional nitric oxide molecules are consumed for each nitric oxide molecule decomposed at 10⁸ r, the G_NO value calculated for the primary decomposition (including the dissociation due to ion‐recombination) is 3.45±0.35. The GNO₂ value is 1.2 for a dose of 3×10⁹ r and 0.5 for 5×10⁷ r, conducted under a radiation intensity of 1.2×10⁷ r | min and a filling pressure of 550 mm of the 2 NO₂⇄N₂O₄ equilibrium at 21°C. For the principal reactions in the nitric oxide and nitrogen dioxide systems, when irradiated with ionizing radiation, a reaction mechanism is proposed which seems to explain the characteristic features of the system.