Investigation of the long term corrosion resistance of the overpack FY2006 (Contract research)

Tachikawa, Hirokazu*; Kawakubo, Fumie*; Shimizu, Akihiko*; Shibata, Toshio*; Azumi, Kazuhisa*; Inoue, Hiroyuki*; Sugimoto, Katsuhisa*; Tsuru, Toru*; Fujimoto, Shinji*

JAEA-Research 2007-086, 74 Pages, 2008/02

JAEA-Research-2007-086.pdf:5.96MB

The corrosion life time of the overpack has been investigated on the basis of experimental data and past research, assuming the ranging geological environment of Japan. However, some subject for the realization of the overpack design, such as the behavior of the overpack under high pH conditions, the behavior of the overpack with change of near-field environmental condition and the corrosion behavior of the welds have still been left. To take into account these conditions, expert committee composed of metal corrosion science experts were established in the Nuclear Safety Research Association and past research outcomes and the theory of safety assessment for long term corrosion resistance were investigated from the view points of metal corrosion science.

R&D of a MW-class solid-target for spallation neutron source

Kawai, Masayoshi*; Furusaka, Michihiro*; Kikuchi, Kenji; Kurishita, Hiroaki*; Watanabe, Ryuzo*; Li, J.*; Sugimoto, Katsuhisa*; Yamamura, Tsutomu*; Hiraoka, Yutaka*; Abe, Katsunori*; et al.

Journal of Nuclear Materials, 318, p.35 - 55, 2003/05

R&D works for MW class solid target composed of tungsten to produce pulsed intense neutron source has been made in order to construct a future scattering facility. Three methods were investigated to prevent corrosion of tungsten from water; those are hipping, brazing and electric coating in molten salt bath. Hipping condition was optimized to be 1500 degree C in the previous work: here small punch test shows highest load for crack initiation of hipped materials at the boundary of W/Ta. The basic techniques for the other two methods were developed. Erosion test showed that uncovered W is susceptible of flowing water velocity. At high velocity w is easy to be eroded. For solid target design slab type and rod type targets were studied. As long as the optimized neutron performance is concerned, 1MW solid target is better than mercury target.

Development of the corrosion models for the analysis of candidate materials for overpacks

Shibata, Toshio*; ; ; Tsuru, Toru*; Inoue, Hiroyuki*;

JNC TJ8400 2002-059, 139 Pages, 2003/02

JNC-TJ8400-2002-059.pdf:7.07MB

A technical committee was organized in Japan Society of Corrosion Engineering (JSCE) to review and assess the study of overpack in JNC. The corrosion models for candidate materials for overpacks were developed in terms of corrosion science to contribute the selection of material, establishment of experimental methods and lifetime prediction of overpacks. It is expected that this report is used for the study of overpacks in the process of the research and development of high-level radioactive waste disposal.

Thermodynamic study on redox reactions of boiling nitric acid solutions

Kato, Chiaki; Kiuchi, Kiyoshi; Sugimoto, Katsuhisa*

Corrosion Engineering, 52(1), p.69 - 85, 2003/01

It is necessary to know the generation mechanism of high equilibrium potential in the solutions. Existing nitrogen oxides in nitric acid solutions were first analyzed by Raman spectroscopy and then existing amount of nitrogen oxides were examined by thermodynamic calculation using the SOLGASMIX software. The Raman spectroscopic analysis showed that the existing amount of un-dissociated HNO increased with increasing nitric acid concentration and solution temperature. The thermodynamic calculation showed that the important nitrogen oxides in nitric acid solutions are HNO, NO, HNO, NO, and NO. The equilibrium potential of nitric acid solutions is, however, mainly decided by the HNO/HNO equilibrium. The thermodynamic calculation also suggested that the increased oxidization potential on the heat-transfer surface is attributed to the reduction of nitrous acid concentration by the thermal decomposition of nitrous acid on the surface and the continuous removal of decomposition product from the solutions by boiling bubbles.

Effects of a heat-transfer on corrosion of zirconium in a boiling nitric acid solution

Kato, Chiaki; Yano, Masaya*; Kiuchi, Kiyoshi; Sugimoto, Katsuhisa*

Zairyo To Kankyo, 52(1), p.35 - 43, 2003/01

http://joi.jlc.jst.go.jp/JST.Journalarchive/jcorr1991/52.35

The effects of heat-transfer on the corrosion of zirconium was examined in boiling nitric acid solutions with various concentrations. Corrosion mass losses and electrochemical polarization curves were measured on the heat-transfer and isothermal surfaces in the solutions. It was found that the corrosion rate of zirconium was higher on the heat-transfer surface than that on the isothermal surface. The rate increased with increasing nitric acid concentration and solution temperature. The increased oxidization potential on the heat-transfer surface is attributed to the reduction of nitrous acid concentration by the thermal decomposition on the surface and the removal of the decomposition product from solution by boiling bubbles. The redox potential of 12 mol/dm3 nitric acid on a boiling heat-transfer surface was very close to the breakdown potential of primary passivity of zirconium. This suggests the initiation of SCC on a boiling heat-transfer surface in a nuclear fuel reprocessing.

Development of the corrosion models for the analysis of candidate materials for overpacks

Shibata, Toshio*; ; ; Tsuru, Toru*; Inoue, Hiroyuki*

JNC TJ8400 2001-008, 92 Pages, 2001/02

JNC-TJ8400-2001-008.pdf:2.17MB

A technical committee was organized in Japan Society of Corrosion Engineering to review and assess the study of overpacks in JNC. The corrosion models for candidate materials for overpaks were developed in terms of corrosion science to contribute the selection of material, establishment of experimental methods and life prediction of overpacks. It is expected that this report is used for the study of overpacks in the process of the research and development of high-level radioactive waste disposal.

None

Tsujikawa, Shigeo*; ; ; Tsuru, Toru*; Shibata, Toshio*;

PNC TJ1560 98-001, 164 Pages, 1998/02

PNC-TJ1560-98-001.pdf:3.9MB

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; ; ; Tsuru, Toru*; Shibata, Toshio*;

PNC TJ1560 96-001, 147 Pages, 1996/03

PNC-TJ1560-96-001.pdf:4.66MB

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