METHOD FOR RE-EXTRACTING PLUTONIUM FROM ORGANIC TRIBUTYL PHOSPHATE SOLUTION Russian patent published in 2011 - IPC G21C19/46 

FIELD: physics, nuclear.

SUBSTANCE: invention relates to recovery of plutonium from spent nuclear fuel using aqueous methods. The reducing agent used in operations for separating plutonium from uranium and in operations for plutonium affinage is carbohydrazide CO(N₂H₃)₂ in concentration of 0.2-1.0 mol/l. The lower limit of concentration of the reducing agent is defined by the need to ensure sufficiently high rate of reducing Pu (IV); the upper limit of concentration is defined by the need to save carbohydrazide. The working region of concentration of nitric acid for re-extraction of plutonium with carbohydrazide is in the interval from 0.25 to 1.0 mol/l HNO₃. This interval avoids the risk of polymerisation of plutonium at low acidity and provides its complete re-extraction. Temperature at which the re-extraction process takes place (from 20 to 35°C) corresponds to real production conditions without the need for a special operation for heating solutions.

EFFECT: complete re-extraction of plutonium form organic tributyl phosphate solution without formation of hydrazoic acid.

3 cl, 1 tbl