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Tanaka, Takuro*; Fukuoka, Masafumi*; Toda, Kanako*; Nakanishi, Takahiro; Terashima, Motoki; Fujiwara, Kenso; Niwano, Yuma*; Kato, Hiroaki*; Kobayashi, Natsuko*; Tanoi, Keitaro*; et al.
ACS ES&T Water (Internet), 4(8), p.3579 - 3586, 2024/08
Saito, Takumi*; Nishi, Shusaku*; Amano, Yuki; Beppu, Hikari*; Miyakawa, Kazuya
ACS ES&T Water (Internet), 3(12), p.4103 - 4112, 2023/12
Hata, Kuniki; Uchida, Shunsuke; Hanawa, Satoshi; Chimi, Yasuhiro; Sato, Tomonori
Proceedings of 21st International Conference on Environmental Degradation of Materials in Nuclear Power Systems - Water Reactors (Internet), 14 Pages, 2023/08
Cs supply from rivers to coastal waters off Fukushima considering human activitiesIkenoue, Tsubasa; Shimadera, Hikari*; Nakanishi, Takahiro; Kondo, Akira*
Water (Internet), 15(15), p.2734_1 - 2734_18, 2023/08
Times Cited Count：0 Percentile：0.00(Environmental Sciences)The Fukushima Daiichi Nuclear Power Plant accident caused an accumulation of Cs in coastal sediment. The Cs supply from rivers to the ocean can affect the long-term fate of Cs in coastal sediment. Since the Fukushima coastal river basins include large decontaminated and evacuation order areas, considering the decontamination work and resumption of agriculture is important for predicting the Cs supply. We conducted a 30-year prediction of the Cs supply from the Fukushima coastal rivers to the ocean using a distributed radiocesium prediction model, considering the effects of human activities. In river basins with decontaminated and evacuation order areas, human activities reduced the total Cs outflow from agricultural lands, urban lands, and forest areas to the rivers and the Cs supply to the ocean by 5.0% and 6.0%, respectively. These results indicated that human activities slightly impacted the Cs outflow and supply. The Cs supply from rivers impacted by the accident to the coastal sediment was estimated to correspond to 11-36% of the total Cs in the coastal sediment in the early phase of the accident. Therefore, the Cs supply from rivers to the ocean is important for the long-term behavior of Cs in coastal sediment.
Idham, M. F.*; Falyouna, O.*; Eljamal, R.*; Maamoun, I.; Eljamal, O.*
Journal of Water Process Engineering (Internet), 50, p.103289_1 - 103289_16, 2022/12
Times Cited Count：32 Percentile：94.76(Engineering, Environmental)Eljamal, O.*; Maamoun, I.; Alkhudhayri, S.*; Eljamal, R.*; Falyouna, O.*; Tanaka, Kazuya; Kozai, Naofumi; Sugihara, Yuji*
Journal of Water Process Engineering (Internet), 46, p.102608_1 - 102608_13, 2022/04
Times Cited Count：44 Percentile：97.82(Engineering, Environmental)Hanawa, Satoshi; Hata, Kuniki; Chimi, Yasuhiro; Kasahara, Shigeki
Proceedings of 21st International Conference on Water Chemistry in Nuclear Reactor Systems (Internet), 12 Pages, 2019/09
Fukuya, Koji*; Fujii, Katsuhiko*; Chimi, Yasuhiro; Hata, Kuniki
Proceedings of 19th International Conference on Environmental Degradation of Materials in Nuclear Power Systems - Water Reactors (Internet), p.523 - 531, 2019/08
For structural integrity assessment on reactor internals of light water reactors, empirical equations of tensile properties as a function of neutron dose, and trend curves of stress-strain relations of neutron-irradiated austenitic stainless steels was proposed by fitting to recently developed database. The data in the database were obtained from reports of national projects in Japan and open literature, which was summarized in the form of data sheets. The empirical equations for tensile properties were formulated by using a saturation-type formulae. The equations were for CW 316 and SA 304/316 stainless steels in the temperature range of 280-350
C and the dose range up to 80 dpa. Stress-strain relation curves were reproduced based on the Swift model. Obtained calculated results by the empirical equations and stress-strain relations were reasonably well fitted to experimental data. The effects of composition and cold-working, etc. on tensile properties were discussed.
Kasahara, Shigeki; Chimi, Yasuhiro; Hata, Kuniki; Fukuya, Koji*; Fujii, Katsuhiko*
Proceedings of 19th International Conference on Environmental Degradation of Materials in Nuclear Power Systems - Water Reactors (Internet), p.1345 - 1355, 2019/08
This paper describes empirical equation development of crack growth rates (CGR) in consideration of IASCC of neutron irradiated stainless steel to contribute to structural integrity assessment of BWR reactor internals. Empirical equations of CGR (da/dt) were developed based on a formula of da/dt = M
K
, assuming that "M" and "n" tend to be saturated with increasing neutron fluence. To obtain the empirical equations for normal water chemistry (NWC) and hydrogen water chemistry (HWC) of BWR, a data fitting with least square method was applied to the datasets consisting of F, K and CGR from post irradiation examinations of neutron irradiated stainless steel under simulated NWC and HWC conditions from open literature. As a result, calculated results by the equation for NWC showed good agreement with measured CGR data, meanwhile those for HWC did not. The above difference was seemed to be attributed that CGR data obtained under HWC conditions were scattered extensively.
Chimi, Yasuhiro; Sato, Kenji*; Kasahara, Shigeki; Umehara, Ryuji*; Hanawa, Satoshi
Proceedings of Contribution of Materials Investigations and Operating Experience to Light Water NPPs' Safety, Performance and Reliability (FONTEVRAUD-9) (Internet), 10 Pages, 2018/09
To investigate the influence of Zinc (Zn) injection on primary water stress corrosion cracking (PWSCC) growth behavior, crack growth tests of 10% cold-worked Alloy 600 were performed in simulated primary water environment of pressurized water reactor (PWR) at 320C with a low-concentration (5-10 ppb) Zn injection under dissolved hydrogen (DH) conditions of 5, 30, and 50 cc/kgH
O. As a result of the crack growth tests, DH-dependence of crack growth rate (CGR) showed a similar tendency to the predicted CGR based on the CGR data without Zn injection, indicating almost no effect of a low-concentration Zn injection on the crack growth behavior. Moreover, the microstructural analyses of oxide films formed inside the crack and on the specimen surface were conducted, and the intake of Zn in the oxides was detected on the specimen surface, but not detected inside the crack. This result was considered to be the cause of no Zn injection effect on the crack growth behavior.
Sato, Yuhi; Otosaka, Shigeyoshi; Suzuki, Takashi
Journal of Water and Environment Technology (Internet), 12(2), p.201 - 210, 2014/04
An easy and fast method for determination of total iodine in environmental samples by cathodic stripping voltammetry combined with NaClO oxidation has been developed. Adequate conditions for NaClO oxidation of 40-50C over 2 h were determined, using three representative environmental samples (reference soil, seabed sediment, seaweed). By analyzing a mixture of thyroxin and a reference soil material, we obtained an overall recovery of more than 97% for total iodine in the concentration range of 1-7 
mol g
. This method was compared with alkaline extraction and combustion methods for solid and aqueous environmental samples. Alkaline extraction exhibited lower recovery of iodine compared with the NaClO oxidation method, indicating insufficient extraction and/or interference on determination. Combustion method also showed lower iodine recovery for some samples, probably due to a trapping efficiency and incomplete combustion of organic matter.
Oba, Ryoji*; Bushnak, A.*; Kojiri, Toshiharu*; Matsuura, Tomonori*; Nagai, Haruyasu
Proceedings of the 3rd International Conference on Water Resources and Arid Environments 2008 and the 1st Arab Water Forum (Internet), 12 Pages, 2008/11
no abstracts in English
OSato, Tomonori; Tsukada, Takashi; Uchida, Shunsuke
Proceedings of 15th International Conference on the Properties of Water and Steam (15th ICPWS) (Internet), 10 Pages, 2008/09
In this study, in order to determine the effects of HO on corrosion of stainless steel, the analyses of the oxide film at the surface of specimens after exposure to the high temperature water containing HO. And the modified double oxide layer model was developed based on the obtained results. The major results are listed in follows; (1) The double oxide layer with a tight inner oxide layer which was formed by direct oxidation and a porous outer oxide layer which consisted of the oxide particles formed by the oxidation of dissolved ferrous ions released from inner oxide layer was confirmed. (2) The Fe
O
particles were formed by the oxidation of dissolved ferrous ions and precipitated. In higher HO concentration condition, the particles consisted of the mixture of FeO and 
-FeO particles due to the oxidation of FeO to -FeO. (3) Modified double oxide layer model was developed. Calculated results were qualitatively agreed with measured data.
Matsunaga, Takeshi; Yanase, Nobuyuki; Hanzawa, Yukiko; Tsuzuki, Katsunori; Naganawa, Hirochika
Journal of Water and Environment Technology (Internet), 3(2), p.243 - 252, 2005/00
In a tributary watershed of the Kuji River of Japan, the hydrological components of runoff associated with a rain storm event were investigated using isotope tracers of hydrogen (
H) and oxygen (
O) in precipitations and stream water. The runoff was separated into either "old water" (pre-existing in the ground before the storm) and "new water"(from the storm precipitation). It was found that the discharge of several hazardous trace elements (Sb, Cu, Cr) was largely (24-54%) attributable to that of the new water in spite of its small contribution to the total water discharge. These investigations suggest that the new water may play an important role in the migration of atmospherically derived, hazardous trace elements to streams during rain storms.
