In:
Radiochimica Acta, Walter de Gruyter GmbH, Vol. 100, No. 11 ( 2012-11), p. 813-820
Abstract:
A study of the electrochemical behaviors of N , N -dimethylhydroxylamine (DMHAN) and monomethyl hydrazine (MMH) in nitric acid solution on Pt electrodes were carried out by cyclic voltammetry (CV) and linear sweep voltammetry (LSV) methods. The diffusion coefficients of DMHAN and MMH were obtained by CV. The values are found to be 0.53 × 10 6 cm 2 /s D (DMHAN ) and 0.88 × 10 5 cm 2 /s D (MMH ) . The equilibrium potentials (+0.47 V vs. SCE for DMHAN and +0.31 V vs . SCE for MMH) were also measured using Tafel curves. Various valence states of Pu and Np in HNO 3 solution containing DMHAN and MMH in the electrolytic process were investigated by an electrolytic cell using a platinum as the anode and a titanium plate as the cathode. In this procedure, MMH was first electro-oxidized on the Pt anode and Np(V) was reduced to Np(IV) on the Ti cathode. After MMH was entirely consumed, the accumulation of HNO 2 (due to the electrochemical reduction of nitric acid on the Ti cathode) caused a significantly fast catalytic reaction of DMHAN with HNO 3 to form HNO 2 . HNO 2 can oxidize Pu(III) to Pu(IV) quickly. As a result, both oxidation states of Pu and Np were found to be tetravalent in the post-electrolysis solution. A convenient method to keep the post-electrolysis solution at 70 ºC was used to adjust the oxidation state of Np in it's pentavalent state while retaining the tetravalent state of Pu. This study developed an electrolytic process for the preparation of 2AF feed (the feed of Pu purification cycle) in APOR (Advanced Purex Process Based on Organic Reductants) process by electrochemically oxidizing Pu(III) and selectively adjusting the valence state of neptunium to either Np(IV) or Np(V).
Type of Medium:
Online Resource
ISSN:
2193-3405
DOI:
10.1524/ract.2012.1979
Language:
English
Publisher:
Walter de Gruyter GmbH
Publication Date:
2012
