Release of Nitrogen Oxides into the Gas Phase Accompanying the Dissolution of Uranium Nitride in Nitric Acid

The release of nitrogen oxides (N 2 O, NO, NO 2 ) accompanying the dissolution of UN in HNO 3 with concentration 3–16 mol/liter and the ratio S:L = 1:7.5 and in 7.2 mol/liter HNO 3 with S:L varying from 3 to 30 in atmospheric air or argon is studied. In the indicated HNO 3 concentration range N 2 O is formed mainly as a result of the oxidation of UN and secondarily as a result of the reduction of HNO 3 . The presence or absence of oxygen in the atmosphere has no effect on the amount of N 2 O formed. The formation of NO 2 is due to the reduction of HNO 3 . The presence of oxygen increases the amount of NO 2 formed as a result of the oxidation of NO. The amount of nitrogen monoxide NO released into atmospheric air is higher than the amount released into an argon atmosphere. The amount of NO formed increases with increasing nitric acid concentration. The release of nitrogen oxides from UN as well as from nitric acid results in considerable dilution of nitride nitrogen, which casts doubt on the possibility of recycling 15 N in the case where U 15 N is used as fuel.