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Yamamoto, Masahiro; Sato, Tomonori; Igarashi, Takahiro; Ueno, Fumiyoshi; Soma, Yasutaka
Proceedings of European Corrosion Congress 2017 (EUROCORR 2017) and 20th ICC & Process Safety Congress 2017 (USB Flash Drive), 6 Pages, 2018/09
The authors have studied the differences between outer surface and the crevice-like portion of SUS316L in high pressurized and high temperature water containing dissolved oxygen. We have already introduced that changes in the characteristics of corrosion products along the crevice directions and gap width. It is suggested that the environmental conditions are different with the features of crevice from these results. In this report, we introduce the changes in oxide films with crevice gaps and comparison with the numerical simulation data utilizing of FEM calculation.
Haga, Katsuhiro; Kogawa, Hiroyuki; Wakui, Takashi; Naoe, Takashi; Takada, Hiroshi
Journal of Nuclear Science and Technology, 55(2), p.160 - 168, 2018/02
Times Cited Count：5 Percentile：45.59(Nuclear Science & Technology)The mercury target vessel used for the spallation neutron source in J-PARC has multi-walled structure made of stainless steel type 316L, which comprises a mercury vessel and a water shroud. In 2015, water leak incidents from the water shroud occurred while the mercury target was operated with a proton beam power of 500 kW. Several investigations were conducted to identify the cause of failure. The results of the visual inspections, mockup tests, and analytical evaluations suggested that the water leak was caused by the combination of two factors. One was the diffusion bonding failure due to the large thermal stress induced by welding of the bolt head, which fixes the mercury vessel and the water shroud, during the fabrication process. The other was the thermal fatigue failure of the seal weld due to the repetitive beam trip during the operating period. These target failures point to the importance of eliminating initial defects from welding lines and to secure the rigidity and reliability of welded structures. The next mercury target was fabricated with an improved design which adopted parts of monolithic structure machined by wire EDM to reduce welding lines, and intensified inspections to eliminate the initial defects. The operation with the improved target is planned to be started in October 2017.
Komatsu, Atsushi; Tsukada, Takashi; Ueno, Fumiyoshi; Yamamoto, Masahiro
Proceedings of 23rd International Conference on Nuclear Engineering (ICONE-23) (DVD-ROM), 4 Pages, 2015/05
Effect of oxygen and hydrogen peroxide on corrosion rate of carbon steel in diluted artificial seawater was investigated by electrochemical methods. Diffusion coefficient and thickness of diffusion layer for oxygen and hydrogen peroxide were measured to estimate the diffusion limiting current density. Corrosion tests of carbon steel were also conducted in diluted artificial seawater containing oxygen and/or hydrogen peroxide at 323K. The diffusion coefficient of hydrogen peroxide was about 0.8 times lower than that of oxygen, and the thickness of diffusion layer was almost equivalent between oxygen and hydrogen peroxide. Diffusion limiting current density of hydrogen peroxide was estimated to be 0.4 times lower than that of oxygen in the same concentration at 323K. Plot of corrosion rate with the addition of concentration of oxygen and 0.4 times concentration of hydrogen peroxide showed good correlation.
Shimazaki, Yosuke; Isaka, Kazuyoshi; Nomoto, Yasunobu; Seki, Tomokazu; Ohashi, Hirofumi
JAEA-Technology 2014-038, 51 Pages, 2014/12
JAEA-Technology-2014-038.pdf:3.84MB
The analytical models for the evaluation of graphite oxidation were implemented into the THYTAN code, which employs the mass balance and a node-link computational scheme to evaluate tritium behavior in the High Temperature Gas-cooled Reactor (HTGR) systems for hydrogen production, to analyze the graphite oxidation during the air or water ingress accidents in the HTGR systems. This report describes the analytical models of the THYTAN code in terms of the graphite oxidation analysis and its verification and validation (V&V) results. Mass transfer from the gas mixture in the coolant channel to the graphite surface, diffusion in the graphite, graphite oxidation by air or water, chemical reaction and release from the primary circuit to the containment vessel by a safety valve were modeled to calculate the mass balance in the graphite and the gas mixture in the coolant channel. The computed solutions using the THYTAN code for simple questions were compared to the analytical results by a hand calculation to verify the algorithms for each implemented analytical model. A representation of the graphite oxidation experimental was analyzed using the THYTAN code, and the results were compared to the experimental data and the computed solutions using the GRACE code, which was used for the safety analysis of the High Temperature Engineering Test Reactor (HTTR), in regard to corrosion depth of graphite and oxygen concentration at the outlet of the test section to validate the analytical models of the THYTAN code. The comparison of THYTAN code results with the analytical solutions, experimental data and the GRACE code results showed the good agreement.
Taguchi, Mitsumasa; Kojima, Takuji
JAEA-Review 2005-001, TIARA Annual Report 2004, p.181 - 182, 2006/01
The yields of OH radicals in water containing phenol have been investigated for several ten MeV/n C ion and Ne ion having the same LET value, as a function of the residual ion energy at the specific depth in water. In this study, beside such energy dependence, the dependence of reaction time of OH radical yield was examined by changing the concentration of phenol as solute. The defferential G'-values of OH radicals, those G-values per kinetic energy of ions increase with specific energy of Ne ions. The G'-value just after irradiation(1.5ns) is relatively high but become lower with reaction time to be the value (2.7) obtained for 
Co 
-rays. It suggests the diffusion behavior of OH radicals locally induced in water.
Koarashi, Jun*; Iida, Takao*; Atarashi-Andoh, Mariko; Yamazawa, Hiromi; Amano, Hikaru
Fusion Science and Technology, 41(3), p.464 - 469, 2002/05
no abstracts in English
J.T.Lindsay*; Matsubayashi, Masahito; M.N.Islam*
Fifth World Conf. on Neutron Radiography, 0, p.644 - 649, 1996/00
no abstracts in English
J.T.Lindsay*; Matsubayashi, Masahito; Md.N.Islam*
Nuclear Instruments and Methods in Physics Research A, 353, p.149 - 151, 1994/00
Times Cited Count：8 Percentile：63.71(Instruments & Instrumentation)no abstracts in English
*; ; *; *
Kozan Chishitsu, 40(5), p.323 - 336, 1990/00
no abstracts in English
JAERI-M 85-059, 69 Pages, 1985/05
no abstracts in English
; ; *;
Journal of Nuclear Science and Technology, 22(10), p.833 - 840, 1985/00
Times Cited Count：3 Percentile：47.04(Nuclear Science & Technology)no abstracts in English
JAERI-M 83-098, 21 Pages, 1983/07
no abstracts in English
; Akino, Fujiyoshi; *; ; ;
Nuclear Science and Engineering, 55(1), p.105 - 116, 1974/01
Times Cited Count：3no abstracts in English
O-Al Square Lattices by PulsedNeutron Method; Akino, Fujiyoshi; *; ; ;
JAERI-M 5351, 34 Pages, 1973/08
no abstracts in English
Tachi, Yukio; Yotsuji, Kenji; Ito, Tsuyoshi; Suyama, Tadahiro
no journal, ,
The integrated sorption and diffusion (ISD) model was applied for systems coexisting multispecies Sr (divalent cation Sr
and neutral SrSO
(aq)) in compacted montmorillonite. Effective diffusion coefficients (De) and distribution coefficients (Kd) of Sr in compacted Na-montmorillonite (dry density of 800 kg/m
) saturated with three types of NaSO solutions (0.05, 0.1, 0.5 M) were measured by the trough-diffusion method. The De and Kd values decreased drastically with increasing porewater salinity. The De for multispecies Sr was determined as the harmonic weight-average considering the two species distribution and their log De values, based on comparison with reactive-transport calculations using the PHREEQC. As a result, the De trend could be quantitatively express by the ISD model considering multispecies contributions. The thermodynamic sorption model considering ion exchange reactions could provide reasonable account of Kd trend as functions of salinity.
