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REDOX BEHAVIOUR OF NEPTUNIUM IN PUREX EXTRACTION PROCESSES

Research Project

Project/Area Number 03453166
Research Category

Grant-in-Aid for General Scientific Research (B)

Allocation TypeSingle-year Grants
Research Field Nuclear engineering
Research InstitutionTOHOKU UNIVERSITY

Principal Investigator

INOUE Yasushi  Tohoku University,Faculty of Engineering,Professor, 工学部, 教授 (60005858)

Co-Investigator(Kenkyū-buntansha) TOCHIYAMA Osamu  Tohoku University,Faculty of Engineering,Associate Professor, 工学部, 助教授 (70005479)
Project Period (FY) 1991 – 1992
Project Status Completed (Fiscal Year 1992)
Budget Amount *help
¥6,500,000 (Direct Cost: ¥6,500,000)
Fiscal Year 1992: ¥1,000,000 (Direct Cost: ¥1,000,000)
Fiscal Year 1991: ¥5,500,000 (Direct Cost: ¥5,500,000)
Keywordsneptunium / nitrous acid / nitric acid / Purex process / solvent extraction / TBP / oxidation / kinetics
Research Abstract

In order to clarify the distribution behavior of neptunium in the Purex extraction processes, the equilibrium and rate of the extraction of neptunium into 30% TBP-dodecane were examined as a function of nitrous acid (3-6 M) and nitrous acid (10^<-4>-10^<-2> M) concentrations. It was shown that the rapid equilibrium between nitric and nitrous acids controlls the redox potential of the aqueous phase, which in turn controlls the ratio of the concentrations of extractable Np(VI) to unextractable Np(V). The redox potential can be quantitatively described with using the activities of nitric acid, nitrous acid and water in nitric acid solutions:
E/V = 0.951 + 0.058・log<@D7{HNO<@D23@>D2}<@D12@>D1(/){HNO<@D22@>D2}<@D11/2@>D1{H<@D22@>D2O}<@D11/2@>D1@>D7 By examining also the rate of the extraction of neptunium into TOPO-dodecane, the ratedetermining step was confirmed to be the oxidation of Np(V) to Np(VI) in the aqueous phase. The rate of the reaction was obtained to be:
k/h = 5.44 x {HNO_3}^<1.02>{HNO_2}^<0.56>

Report

(3 results)
  • 1992 Annual Research Report   Final Research Report Summary
  • 1991 Annual Research Report
  • Research Products

    (4 results)

All Other

All Publications (4 results)

  • [Publications] 井上 泰: "ピュレックス工程におけるネプツニウムの酸化還元挙動" 日本原子力学会1991年秋の大会講演要旨集. 674 (1991)

    • Description
      「研究成果報告書概要(和文)」より
    • Related Report
      1992 Final Research Report Summary
  • [Publications] Y.Inoue,O. Tochiyama and Y.Nakamura: "Redox Behavior of Neptunium in Purex Extraction Process" 1991 Fall Meeting of the Atomic Energy Society of Japan. 674 (1991)

    • Description
      「研究成果報告書概要(欧文)」より
    • Related Report
      1992 Final Research Report Summary
  • [Publications] 井上 泰: "ピュレックス工程におけるネプツニウムの酸化還元挙動" 日本原子力学会 1991年秋の大会講演要旨集.

    • Related Report
      1992 Annual Research Report
  • [Publications] 井上 泰: "ピュレックス工程におけるネプツニウムの酸化還元挙動" 日本原子力学会1991年秋の大会講演要旨集.

    • Related Report
      1991 Annual Research Report

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Published: 1991-04-01   Modified: 2016-04-21  

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