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in NaClAoyama, Takahito; Ogawa, Hiroaki; Kato, Chiaki; Ueno, Fumiyoshi
Metals, 11(3), p.511_1 - 511_13, 2021/03
Times Cited Count：3 Percentile：25.78(Materials Science, Multidisciplinary)The effect of Cu in bulk solution on pitting corrosion resistance of extra high purity type 316 stainless steel was investigated. Pitting occurred in 0.1 M NaCl-1 mM CuCl
whereas pitting was not initiated in 0.1 M NaCl. Although deposition of Cu on the surface occurred regardless of potential region in 0.1 M NaCl-1 mM CuCl, Cu in bulk solution had no influence on the passive film formation. The decrease in pitting corrosion resistance in 0.1 M NaCl-1 mM CuCl resulted from the deposited Cu or Cu compound and continuous supply of Cu
on the surface.
-ray irradiationKato, Chiaki; Sato, Tomonori; Nakano, Junichi; Ueno, Fumiyoshi; Yamagishi, Isao; Yamamoto, Masahiro
Nihon Genshiryoku Gakkai Wabun Rombunshi, 14(3), p.181 - 188, 2015/09
In relation to the consideration for long-term storage of spent Cs adsorption vessels containing zeolites in the Fukushima Daiichi Nuclear Power Station, corrosion of the vessel material in the spent Cs adsorption vessel is one of important issues. We performed electrochemical tests of stainless steel (SUS 316L) in the zeolites containing artificial seawater under -ray irradiation. The spontaneous potential (
) and critical pitting potential (
), of SUS 316L were measured to understand the corrosion resistance of the stainless steel in this study. The rest potential of the stainless steel increased with increasing time after -ray irradiation. The , defined as the steady rest potential, increased with increasing dose rate, while increasing was suppressed by contact with the zeolites. Concentration of H
O in bulk water increased with increasing dose rate. The concentration increasing was suppressed by contact with the zeolites due to decomposition of HO. There was good relationship between and the concentration of HO. The of SUS 316L contacted with the zeolites decreased with increasing Cl
ion concentration and is slightly smaller than the in the bulk water. The contact with the zeolites causes the suppressant of increasing under the irradiation. The contact with the zeolite can reduce probability in the localized corrosion for SUS 316L.
Iriya, Keishiro*; *; Fujita, Hideki*; Kubo, Hiroshi*
JNC TJ8400 2000-034, 212 Pages, 2000/02
JNC-TJ8400-2000-034.pdf:7.91MB
Cementious materials and highly compacted bentnite are expectable candidates as materials of TRU waste repositories. It was pointed out that Bentonite might be changed to Zeolite and surrounding rock might be altered by high alkalinity water flow, since cement hydrate leached to pore water of cement and it was changed to alkaline. Transportation of radio-nuclides might be accelerated by organic materials, such as super plasticizer, and nitlate which is contained in nuclear wastes. It was concluded by previous studies that rock and bentonite is stable in alkaline water which pH is less than 10.5. The new type of low alkalinity cement with high silica fume and fly ash content which could keep pH below 11.0 was developed and its performance has been assessed. However since Zeolitation and ilitation were reported upon deterioration of bentonite bated in certain condition, it should be assessed by long term experiment. Since Capacity of keeping integrity of bentonite hasn't been directly checked by experiments upon the developed new type of low alkalinity cement it should be done. Although amount of leaching organic was quantitatively and experimentally assessed at an early age, effect of changing of amount and shape hasn't assessed in leaching of radio nuclides. Although it is pointed out that deterioration of cementitious materials isn't accelerated by condensed nitrate solution at early period after closure, it is considered that it might be accelerated corresponding to chemical composition in case of decrement of concentration of nitrate. In this study, deterioration of materials will be assessed in detail in order to feed back the results to assessment of transportation of radio nuclides. Long term deterioration of bentonite by leaching water of cement will be experimentally assessed, and deteriorating test of bentonite will be carried out by leaching water of low alkalinity cement. Amount of organic and component of it will be measured. Furthermore ...
Iriya, Keishiro*; *; Kubo, Hiroshi*; Fujita, Hideki*
JNC TJ8400 2000-033, 95 Pages, 2000/02
JNC-TJ8400-2000-033.pdf:11.11MB
Cementious materials and highly compacted bentnite are expectable candidates as materials of TRU waste repositories. It was pointed out that Bentonite might be changed to Zeolite and surrounding rock might be altered by high alkalinity water flow, since cement hydrate leached to pore water of cement and it was changed to alkaline. Transportation of radio-nuclides might be accelerated by organic materials, such as super plasticizer, and nitrate which is contained in nuclear wastes. It was concluded by previous studies that rock and bentonite is stable in alkaline water which pH is less than 10.5. The new type of low alkalinity cement with high silica fume and fly ash content which could keep pH below 11.0 was developed and its performance has been assessed. However since Zeolitation and ilitation were reported upon deterioration of bentonite bated in certain condition, it should be assessed by long term experiment. Since Capacity of keeping integrity of bentonite hasn't been directly checked by experiments upon the developed new type of low alkalinity cement it should be done. Although amount of leaching organic was quantitatively and experimentally assessed at an early age, effect of changing of amount and shape hasn't assessed in leaching of radio nuclides. Although it is pointed out that deterioration of cementitious materials isn't accelerated by condensed nitrate solution at early period after closure, it is considered that it might be accelerated corresponding to chemical composition in case of decrement of concentration of nitrate. In this study, deterioration of materials will be assessed in detail in order to feed back the results to assessment of transportation of radio nuclides. Long term deterioration of bentonite by leaching water of cement will be experimentally assessed, and deteriorating test of bentonite will be carried out by leaching water of low alkalinity cement. Amount of organic and component of it will be measured. Furthermore ...
Sumiyama, Morio*
JNC TJ8400 2000-009, 138 Pages, 2000/02
To evaluate corrosion behavior of carbon steel, a candidate materials of overpack, buried in soil for a long time, the water pipes buried in freshwater clay for a long time we digged out and the soil environment and the corrosion weight loss of pipes have been researched. From the results, a corrosion model (an empirical equation), an oxygen reduction reaction rate-determing step type, of carbon steel buried in soil was introduced. The corrosion data of under ground pipe collected by the Japan Community Gas Associations was used to increase reliability of the corrosion model equation. These data are one of researches of corrosion behavior of carbon steel buried in soil for a long time studied by at home and abroad. 38 samples buried freshwater clay were selected in 171 samples. With estimating the corrosion velocities and the soil environment factors of the above data, the maximum depth of pit corrosion was calculated by the statistical method of the extreme values using the area of overpack as the recurrent time. The correlation between the soil environment factors and the corrosion weight loss was obtained by the correlation analysis. The corrosion model of the maximum depth of pit corrosion at 0.99 of cumulative probability was compared between the under ground pipe data and the above data. On the reference data and the above data, the corrosion model equation; H = aY
was compared with the maximum depth of pit corrosion at 0.99 cumulative probability. The data of water pipes and community gas pipes at 0.99 cumulative probability showed the reasonable values when these data were compared with the reference data. So that the model was proved as a good corrosion model m the neutral low dissolved oxygen environment.
Imai, Jun*
JNC TJ8400 2000-008, 196 Pages, 2000/02
JNC-TJ8400-2000-008.pdf:25.25MB
The objective of this research is to make clear long-term alteration processes of bentonite contacting with concrete under a repository condition for radioactive waste. The Uzu tunnel in yamagata prefecture in Japan, constructed during the term of December of 1963 to July 1967, was selected as an appropriate natural analogue: the tunnel wall was made of portland cement and which has been contacting with a bentonite bed during 
32 years. Sample analyses indicated that the original bentonite was Na
-type and it changed to Ca-type in the range of a few millimeters from the contact. Although a Ca leaching was also observed from the concrete near the contact, neither transformation to zeolite nor to illite was recognized. On the other hand, sulfur increased and ettringite (3CaO 
AlO
3CaSO
4 32HO) was recognized in the concrete within the depth about 30 mm from the contact.
Matsuda, Fumio*; Wada, Ryutaro*; Fujiwara, Kazuo*
PNC TJ1058 92-001, 270 Pages, 1992/03
no abstracts in English
rays irradiation, 3; Effects on depth of localized corrosionNakano, Junichi; Tsukada, Takashi; Ueno, Fumiyoshi; Yamagata, Ryohei
no journal, ,
In the Fukushima Daiichi Nuclear Power Station, it is considered that corrosion of primary containment vessel (PCV) and reactor pressure vessel (RPV) steels is accelerated by seawater injection and high radiation dose. In general, it is known that weight loss in steels increases near gas-liquid interface. Therefore, the lower half of the specimens was dipped in diluted seawater at 50
C under rays irradiation. Gas phase in flasks was air or N atmosphere. After the tests, oxide layer was removed and 3 dimension (3D) digital data were measured on the specimen surface using a 3D macro-scope. In air atmosphere, the maximum roughness height increased with time and dose rate. After rays irradiation for 500 h, the maximum roughness height in N atmosphere was lower than that in air atmosphere. Since O concentration in liquid was reduced by decrease of O partial pressure in gas phase, it was appeared that localized corrosion was suppressed.
Kato, Chiaki; Sato, Tomonori; Yamagishi, Isao; Arisaka, Makoto; Terada, Atsuhiko
no journal, ,
Electrochemical test of stainless steel (SUS316L) in zeolite containing artificial seawater under gamma-ray irradiation as a basic study on the local corrosion generation conditions of the used adsorption tower used for contaminated water treatment at the Fukushima Daiichi Nuclear Power Plant Accident. In addition, a drying test using the second Cs adsorption tower (SARRY) mock-up was conducted to report the change of Cl concentration in the tower and to investigate the possibility of local corrosion in the used Cs adsorption tower. The steady natural immersion potential of stainless steel became noble by gamma irradiation, and the potential increased as the absorbed dose rate increased. On the other hand, in the zeolite coexisting system, the potential increase under gamma irradiation was suppressed. The mechanism of increasing the potential of stainless steel under gamma irradiation is that HO generated by radiation activates the cathode reaction of stainless steel and that the potential of zeolite decreases to suppress the formation of HO. Also, from the dry test of the mock-up specimen, as the temperature of the zeolite layer rises, the residual water is sucked up by the dry zeolite layer, so that the salt content of the residual water is precipitated in the heat generating part and the evaporated water condenses on the inner surface of the container. It was confirmed that the residual water Cl concentration decreased due to the heat generation in the adsorption tower, which was confirmed by the mock-up test specimen. It was expected as a mitigation measure.
