Zairyo-to-Kankyo
Online ISSN : 1881-9664
Print ISSN : 0917-0480
ISSN-L : 0917-0480
Volume 57 , Issue 12
Showing 1-4 articles out of 4 articles from the selected issue
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Research Paper
  • Takafumi Motooka, Masahiro Yamamoto
    2008 Volume 57 Issue 12 Pages 536-541
    Published: December 15, 2008
    Released: August 25, 2009
    JOURNALS FREE ACCESS
    In order to investigate a corrosion behavior of stainless steel in the typical nuclear fuel reprocessing plant, corrosion tests using nitric acid solution with neptunium were conducted under atmospheric and the reduced pressure conditions in the laboratory where radioactive substance could be handled. An ultra low carbon type of SUS304ULC stainless steel was used. Obtained results were as follows: Under the reduced pressure condition, corrosion of the stainless steel was accelerated in the nitric acid solution with neptunium than in pure nitric acid solution. Under an atmospheric condition, the corrosion rate of the stainless steel increased with increase of neptunium content. The higher solution temperature enhanced the corrosion rate of the stainless steel in the nitric acid solution with neptunium. Thermodynamic data showed that Np(V) oxidized to Np(VI) by concentrated and elevated nitric acid solution. The corrosion potential of the stainless steel shifted to nobler direction in the nitric acid solution with neptunium. It is estimated that the electrochemical reaction of Np(VI)/Np(V) is reversible and the rate constant of the reaction has great values. And it is considered that the dominance of Np(VI) in nitric acid solution accelerated the corrosion rate of the stainless steel in the solutions with neptunium.
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  • Atsushi Nakayama, Kenji Amaya, Norio Yamamoto, Koji Terai
    2008 Volume 57 Issue 12 Pages 542-547
    Published: December 15, 2008
    Released: August 25, 2009
    JOURNALS FREE ACCESS
    We developed the quantitative monitoring method for coating condition inside a ballast tank. We proposed the coating condition is evaluated with the surface resistance. We developed the identification method to obtain the whole surface resistance from the differential potential induced by the impressed current from an optional anode inside a tank. We introduced differential potential measurement and inverse analysis to obtain the surface resistance representing the coating condition. The potential measurement and quantitative evaluation were conducted in the actual ship. The verification was performed and there was the good agreement between the proposed method and the preliminary visual inspection.
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