Supposed existence of Np in a genuine dissolver solution from the results of extraction simulation by PARC-L code

Asakura, Toshihide; Hotoku, Shinobu ; Morita, Yasuji  

With a genuine spent fuel soltuion (a dissolver solution), a laboratory-scale reprocessing experiment of an extraction-separation process was performed using mixer-settlers as extactors. In the experiment, n-butyraldehyde was utilized as a reducing reagent of NpO to NpO for the purpose to distinguish NpO from Np. From the Np concentration in the aqueous phase, Np would be extracted from the dissolver solution together with U and Pu. The scrutiny of Np behavior was performed utilizing 66 cases of calculation results by a Japan Atomic Energy Agency open extraction simulation code, the Programm for Advanced Extraction with Radiation Effect Calculation-Lightened version. From the scrutiny, the authors found that the calculation result with 60% of Np in the dissolver solution represented the best experimental extraction-separtion behavior of Np. Therefore, it was supposed that the dissolver solution contained sufficient proportion of Np to affect the extraction-separation behavior of Np.