The method was successfully used for collecting 239,240Pu from 200 litres seawater by coprecipitation with 16 g FeSO4.7H2O under reducing conditions without filtering. The plutonium is leached by concentrated HNO3 + HCl from the coprecipitate and the solid particles. The precipitate is heated at 400°C and digested in aqua regia. Na2SO3 and NaNO2 have been applied to obtain Pu+4 valence in 0.5-1 N HNO3 for different samples. Plutonium and thorium are coabsorbed on anionic resin from 8 N HNO3. The column is eluated with 8 N HNO3 containing fresh NaNO2 to keep Pu+4 valence for uranium decontamination. The system of the column is changed from 8 N HN03 to concentrated HCl with 50 ml cone. HCl containing a few milligram NaNO2. Further decontamination of thorium was achieved by eluation with concentrated HCl instead of 9 N HCl. The plutonium is successfully stripped by H2O, NaOH, 2 N HNO3 and 0.5 N HNO3 containing 0.01 M NaNO3. The chemical yield of plutonium for a 200 litres-seawater sample is 60-80%. The resolution of the
electroplated thin source is very good.
|Place of Publication||Roskilde|
|Publisher||Risø National Laboratory|
|Number of pages||17|
|Publication status||Published - 1991|