Pilot plant scale denitration by treatment with formaldehyde

An important step in treating the high level liquid wastes (HLLW) of nuclear fuel reprocessing plants for storage is the removal of nitric acid from the fission product waste and its concentration to minimum volume. The continuous denitration of 4 M HNO3 and synthetic waste solutions with HCHO was investigated in pilot plant scale equipment and had been demonstrated for full-scale plant capacity. The reaction was under complete control at all times, though severe foaming could be observed during the reaction. About 1.3 moles of acid were destroyed per mole of formaldehyde with reaction efficiency in the range 70 to 80%. (author)