METHOD OF FIXING PLUTONIUM IN TETRAVALENT STATE (OPTIONS) Russian patent published in 2004 - IPC

FIELD: radiation chemistry. SUBSTANCE: method of fixing plutonium in tetravalent state in aqueous nitric acid solution comprises reduction of Pu(VI) with hydrazine or hydroxylamine until conversion of Pu(III) into Pu(IV) is completed. Termination of oxidation process is judged of by moment when jump increase in solution redox potential is observed, final value of potential being +0.81 to +0.85 v relative to reference silver chloride electrode. Oxidation with nitrogen oxides is conducted at room temperature and at nitric acid concentration 2-3 M, preferably 2.5-3 M, or in 0.5-2 M nitric acid and subsequent acidification to above-indicated nitric acid concentration. Reduction is conducted at 35-45 C in 0.5 to 3,0 M nitric acid solution at molar ratio of initial hydrazine concentration to plutonium concentration between 2 and 10. EFFECT: reduced consumption of reagents and volume of radioactive waste. 10 cl, 4 dwg