Effects of Nitrite on Denitration of Nuclear Fuel Reprocessing Waste with Organic Reductants

Abstract

Denitration with organic reductant such as formic acid is exclusively used for con-trolling acidity of the highly radio-active liquid waste (HLW) from nuclear fuel repro-cessing. This method, however, has a problem in suppressing a vigorous chemical reac-tion. The present study aimed at overcoming the disadvantage by the addition of nitrite to nitric acid solution before denitration.
As a result, the nitrite addition in the denitration of simulated HLW could reduce the induction period to almost zero and the maximum gas evolution rate to less than 60% of that obtained in the absence of nitrite. Effectiveness of nitrite addition was en-hanced especially for HNO₃ concentration higher than 8 mol/l. The effective nitrite con-centration was over 0.01 mol/l in the reaction mixture.