MEASUREMENT OF TECHNETIUM IN THE SPENT FUEL

The extraction-spectrophotometrical determination (with the precision of±1%)of technetium, which recovery is about more than 96%, is described. First Tc inthe NaOH-Na_2CO_3 solution of fission products is extracted into the 2,6-dimethyl-pyridine and reextracted into H_2SO_4 solution from the organic phase by theaddition of CCl_4, then Tc is extracted into tetra-alkyl-ammonium(7402)-n-butylchloride phase by in order to be purified and spectrophotometric determinated.The n-butyl chloride phase contacts with H_2SO_4 solution containing KSCN andbecome purplish red. The colored complex with peak of absorption at 512 nm. hasa molar absorptivity of 5×10~4, and is stable for several hours. Of over 20common metals are studied, none interferes for the spectrophotometricdetermination of Tc. The results of Tc determination of 8 samples from spent fuel elements are incoincidence with the monitor of ~(148)Nd for burnup determination.