Sachio Fujine

Preparation of Novel Silica-Based Nitrogen Donor Extraction Resins and Their Adsorption Performance for Trivalent Americium and Lanthanides

In this work, we have synthesized several 2,6-bis(5,6-dialkyl-1,2,4-triazine-3-yl)pyridine (R-BTP) ligands with different alkyl groups (C=1∼3) and prepared the novel silica-based extraction resins by impregnating the ligands into the SiO 2 -P support. Furthermore, the adsorption performance of Am(III) and Ln(III) from nitrate acidic solution onto these novel silica-based nitrogen donor extraction resins was investigated experimentally.

Theoretical study of lithium isotope separation by displacement chromatography

Lithium isotope separation by displacement chromatography is studied using fundamental principles; the equations are derived assuming theoretical stages in lithium adsorption bands. The concentration profiles in the band are calculated numerically under unsteady state.

Steady-State Characteristics of Lithium Isotope Separation by a Circuit of Continuous Displacement Chromatography

Abstract Height equivalent to a theoretical plate (HETP), which is an important factor to determine separation performance, is experimentally obtained for lithium isotope separation by a circuit of continuous displacement chromatography. The values of HETP are related to the flow rates and concentrations of the displacement reagents. A new equation to estimate HETP is derived and shows good agreement with the experimental data. Diffusion in the resin is found to be the major resistance for the isotope exchange reaction, and liquid mixing in the columns also strongly influences the value of HETP.

The Effects of Temperature and the Use of Macroreticular Resins in Lithium Isotope Separation by Displacement Chromatography

The effects of temperature and the use of macroreticular resins were studied in lithium isotope separation by an ion-exchange method. The isotope separation factors obtained decreased by increasing the temperature, and the factors for macroreticular resins were identical with those for the usual gel-type resins. However, the performance of isotope separation per unit band length in displacement chromatography was found to be improved by increasing the temperature and using macroreticular resins, because accelerating the interphase mass transfer caused the reduction of HETP (Height Equivalent to a Theoretical Plate).

Transient Behavior of Lithium Isotope Separation by Displacement Chromatography

Abstract Lithium isotope concentration profiles at the steady and unsteady states are obtained using the circuit for continuous displacement chromatography, which is composed of 2 cm i.d. columns packed with the strong-acid cation exchange resin, Diaion SK116 (100 μm). These profiles agree well with the results calculated assuming lithium adsorption bands to be square cascades in total reflux operation.

DISTRIBUTION OF NITROUS ACID BETWEEN TRI-N-BUTYL PHOSPHATE/ N-DODECANE AND NITRIC ACID

ABSTRACT The distribution of nitrous add between tri-n-butyl phosphate ( TBP) n-dodecane ( nDD) and nitric add has been measured as functions of nitrous and nitric add concentrations in the aqueous phase and functions of TBP and uranium concentrations in the organic phase The extraction of nitrous add by TBP can be described by the following reaction:

Solvent Extraction Behavior of Minor Nuclides in Nuclear Fuel Reprocessing Process

The solvent extraction behavior of minor nuclides such as neptunium and technetium in a current PUREX process and an advanced PUREX process (PARC process) were studied by chemical flow sheet experiments using spent nuclear fuels. The uranium, plutonium, neptunium and technetium fractions distributed in the products and raffinates of the PARC process showed that n-butyraldehyde was an effective reductant of neptunium(VI) in the presence of uranium(VI) and plutonium(IV). It was also found that scrubbing with high acid concentration was effective for technetium separation.

THE SEPARATION OF NEPTUNIUM AND TECHNETIUM IN AN ADVANCED PUREX PROCESS

ABSTRACT An advanced PUREX process has been developed which can reduce TRU waste volume and the environmental hazard risk due to long-lived nuclides. The separation of neptunium and technetium from plutonium and uranium solutions has been studied before the U/ Pu partitioning step in the PUREX process. The effectiveness of normal-butyraldehyde as a reductant of Np( VI) to Np( V) and of high acid scrubbing of technetium was shown in a basic study and a chemical flowsheet study.

Reduction of neptunium(VI) by butyraldehyde isomers in nitric acid solution

The kinetics of the reaction between Np(VI) and butyraldehyde isomers in nitric acid solution was studied to find flow-sheet conditions of the Np separation process from U and Pu. Iso-butyraldehyde was found to have a higher reduction rate than n-butyraldehyde. The former reduction rate at T = 283 to 323 K is described by the following equation: -d[Np(VI)]/dt = 6.0 X 10 6 exp(-4.1 x 10 3 /T) x [Np(VI)].[iso-C 3 H 7 CHO] 0 . [H + ] (M/min) . The latter reduction rate is described by the following equation : -d[Np(VI)]/dt = 4.2 x 10 4 exp(-3.4 x 10 3 /T) x [Np(VI)].[n-C 3 H 7 CHO] 0 .[H + ] (M/min) .

PARC process for an advanced PUREX process

An advanced PUREX process, the PARC process, has been developed which aims to reduce the radioactive waste volume containing TRU elements (neptunium, plutonium, americium and curium) and the environmental hazard risk due to long-lived nuclides such as technetium-99, carbon-14 and iodine-129. This paper describes the concept of the PARC process and major results of chemical flow sheet experiments using spent fuels.