Kinetic Studies on Dissolution of UO2 Powders in Acid Solutions by Using Cerium(IV) or Chlorine Dioxide as Oxidants.

• ASANO Yuichiro

  Research Laboratory for Nuclear Reactors, Tokyo Institute of Technology

• KATAOKA Makoto

  Research Laboratory for Nuclear Reactors, Tokyo Institute of Technology Hitachi, Ltd.,

• TOMIYASU Hiroshi

  Research Laboratory for Nuclear Reactors, Tokyo Institute of Technology

• IKEDA Yasuhisa

  Kashiwa Laboratory, Institute of Research and Innovation

Abstract

The UO₂ powders of 100-150, 150-212, 212-250, and 250-300μm were dissolved in HNO₃ or HCl solutions containing strong oxidants to examine their effect on the dissolution rates. Cerium(IV) species and ClO₂ were used as oxidants in HNO₃ and HCl solutions, respectively. The Ce(IV) species were prepared by bubbling O₃ gas into HNO₃ solutions containing Ce(NO₃)₃. All dissolution experiments were carried out under rapid stirring conditions which make it possible to neglect the diffusion effect. Dissolution reactions were analyzed on the assumptions that the UO₂ powders are spherical particles and homogeneously dissolved from their external surface. Dissolution rate constants (O) in mol•cm^-2•min^-1 were measured at various concentrations of oxidants and temperatures. Furthermore, the effect of acid concentrations on the dissolution rate was also examined. As a result, the dissolution rate constants Φ were found to be expressed as Φ=kN[Ce(IV)][H⁺]^0.6 for HNO₃ solution([HNO₃]=1-5M, Temp. ?? 30°C) and Φ=kH [ClO₂][H⁺]^-0.3 for HCl solution([HCl]=1-5M, Temp. ?? 530°C), respectively. Activation energies(kJ•mol-1) for the apparent dissolution rate constants are 44.1+1.9 for the HNO₃ solution system and 33.5+2.8 for the HCl solution system, respectively.

Journal

• Journal of Nuclear Science and Technology

  Journal of Nuclear Science and Technology 33 (2), 152-156, 1996

  Atomic Energy Society of Japan

Keywords

• kinetics
• dissolution
• solubility
• uranium dioxide powder
• mild condition
• oxidants
• cerium(IV)
• ozone
• chlorine dioxide
• nitric acid
• hydrochloric acid
• activation energy

Details

• CRID: 1390001204095582976
• NII Article ID: 10002074233
• NII Book ID: AA00703720
• DOI: 10.3327/jnst.33.152
• COI: 1:CAS:528:DyaK28XhvVent7o%3D
• ISSN: 18811248
• ISSN: 00223131
• Text Lang: en
• Data Source:
  • JaLC
  • Crossref
  • CiNii Articles
• Abstract License Flag: Disallowed