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Collaborative Laboratories for Advanced Decommissioning Science; Okayama University*
JAEA-Review 2021-028, 57 Pages, 2021/11
JAEA-Review-2021-028.pdf:1.94MB
The Collaborative Laboratories for Advanced Decommissioning Science (CLADS), Japan Atomic Energy Agency (JAEA), had been conducting the Nuclear Energy Science & Technology and Human Resource Development Project (hereafter referred to "the Project") in FY2020. The Project aims to contribute to solving problems in the nuclear energy field represented by the decommissioning of the Fukushima Daiichi Nuclear Power Station, Tokyo Electric Power Company Holdings, Inc. (TEPCO). For this purpose, intelligence was collected from all over the world, and basic research and human resource development were promoted by closely integrating/collaborating knowledge and experiences in various fields beyond the barrier of conventional organizations and research fields. The sponsor of the Project was moved from the Ministry of Education, Culture, Sports, Science and Technology to JAEA since the newly adopted proposals in FY2018. On this occasion, JAEA constructed a new research system where JAEA-academia collaboration is reinforced and medium-to-long term research/development and human resource development contributing to the decommissioning are stably and consecutively implemented. Among the adopted proposals in FY2018, this report summarizes the research results of the "Interdisciplinary evaluation of biological effect of internal exposure by inhaling alpha-ray emitting nuclides represented by radon" conducted from FY2018 to FY2020. Since the final year of this proposal was FY2020, the results for three fiscal years were summarized. The present study aims to evaluate the influence of radiation exposure to alpha-ray emitting dusts generated in decommissioning of the nuclear reactors. Radon is used here as a surrogate nuclide because it is an alpha-ray emitter and there have been extensive studies on it so far.
Collaborative Laboratories for Advanced Decommissioning Science; Okayama University*
JAEA-Review 2020-029, 55 Pages, 2020/12
JAEA-Review-2020-029.pdf:2.08MB
JAEA/CLADS had been conducting the Nuclear Energy Science & Technology and Human Resource Development Project in FY2019. Among the adopted proposals in FY2018, this report summarizes the research results of the "Interdisciplinary Evaluation of Biological Effect of Internal Exposure by Inhaling Alpha-ray Emitting Nuclides Represented by Radon" conducted in FY2019.
Collaborative Laboratories for Advanced Decommissioning Science; Okayama University*
JAEA-Review 2019-024, 61 Pages, 2020/01
JAEA-Review-2019-024.pdf:2.22MB
CLADS, JAEA, had been conducting the Center of World Intelligence Project for Nuclear Science/Technology and Human Resource Development (hereafter referred to "the Project") in FY2018. The Project aims to contribute to solving problems in nuclear energy field represented by the decommissioning of the Fukushima Daiichi Nuclear Power Station, Tokyo Electric Power Company Holdings, Inc. For this purpose, intelligence was collected from all over the world, and basic research and human resource development were promoted by closely integrating/collaborating knowledge and experiences in various fields beyond the barrier of conventional organizations and research fields. The sponsor of the Project was moved from the Ministry of Education, Culture, Sports, Science and Technology to JAEA since the newly adopted proposals in FY2018. On this occasion, JAEA constructed a new research system where JAEA-academia collaboration is reinforced and medium-to-long term research/development and human resource development contributing to the decommissioning are stably and consecutively implemented. Among the adopted proposals in FY2018, this report summarizes the research results of the "Interdisciplinary Evaluation of Biological Effect of Internal Exposure by Inhaling Alpha-ray Emitting Nuclides Represented by Radon". In the present study, the effect of alpha-ray emission in human body on the surrounding cells is estimated, and biological response to alpha-ray exposure is investigated at the whole organism level, by the evaluation method for radiation effects using radon that is an alpha-ray emitting nuclide, because there have been extensive studies on radon so far. From the obtained results, a model to evaluate the effect of internal exposure by alpha-ray emitting nuclides on health is constructed. Through these studies, we aim to form a research base by the interdisciplinary organic collaboration among research organizations.
Kato, Chiaki; Sato, Tomonori; Ueno, Fumiyoshi; Yamagishi, Isao
Proceedings of 17th International Conference on Environmental Degradation of Materials in Nuclear Power Systems - Water Reactors, Vol.2, p.1357 - 1374, 2016/05
With respect to the long-term storage of the zeolite-containing spent Cs adsorption vessels used at the Fukushima Daiichi Nuclear Power Station, the corrosion of the vessel material is one of the most important issues. In this study, we performed electrochemical tests on stainless steel specimens in zeolite-containing artificial seawater under gamma-ray irradiation. The spontaneous potential ESP and critical pitting potential VC of the type 316L steel in systems in contact with various zeolites were measured in order to evaluate the corrosion resistance of the steel. In addition, the water sample was analyzed after being irradiated, in order to determine the concentrations of various dissolved oxidants such as oxygen and hydrogen peroxide, which can accelerate the corrosion process. The steady-state rest potential increased with an increase in the dose rate; however, the increase was suppressed in contact with the zeolites. The VC value of the steel when in contact with the zeolites was slightly smaller than the VC value in bulk water; however, the choice of the zeolite used as herschelite, IE96 and IE911 hardly affect the VC value. The concentration of H
O in the bulk water under irradiation also increased with the increase in the dose rate. This increase was suppressed in the systems in contact with the zeolites, owing to the decomposition of the HO by the zeolites. A clear relationship was observed between ESP and the HO concentration. As contact with the zeolites caused the increase in ESP under irradiation to be suppressed, it can be concluded that the presence of zeolites in the spent Cs adsorption vessels can reduce the probability of the localized corrosion of the stainless steel in the vessels.
radiolysis of sodium chloride solutions containing a small amount of bromide ionHata, Kuniki; Inoue, Hiroyuki*; Kojima, Takao*; Iwase, Akihiro*; Kasahara, Shigeki; Hanawa, Satoshi; Ueno, Fumiyoshi; Tsukada, Takashi
Nuclear Technology, 193(3), p.434 - 443, 2016/03
Times Cited Count：13 Percentile：77.16(Nuclear Science & Technology)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.
Hayashi, Takumi; Ito, Takeshi*; Kobayashi, Kazuhiro; Isobe, Kanetsugu; Nishi, Masataka
Fusion Engineering and Design, 81(8-14), p.1365 - 1369, 2006/03
Times Cited Count：19 Percentile：77.5(Nuclear Science & Technology)In a fusion reactor, high-level tritiated water of more than GBq/ml will be generated and stored temporally in the various areas. High level tritiated water decomposes by itself and generates hydrogen and oxygen, and becomes to tritiated hydrogen peroxide water, however, effective G-values from tritiated water are different from those obtained -ray experiments in our previous report. Furthermore, tritiated water of about 250GBq/ml has been stored for several years safely and checked its characteristics. Using the above experiences, this paper summarizes safety requirements for storage of high-level tritiated water and discusses design issues of the safety storage system. Concerning gaseous species, storage tank should be maintained at negative pressure and purged periodically or constantly to dedicated tritium removal system. Specially, it is important that the G-value of high-level tritiated water is increasing with decreasing the tritium concentration. The pH and ORP (Oxidation Reduction Potential) of tritiated water have been also changed depending on the tritium concentration and maintained for more than several years in glass vessel. High-level tritiated water of more than GBq/ml was acid and became to be corrosive depending on the dissolved species. Large amount of tritiated water will be stored in the various tanks of stainless steel, therefore, it should be monitored so that the liquid situation is maintained not to be corrosive.
Hanawa, Satoshi; Hata, Kuniki; Uchida, Shunsuke; Nishiyama, Yutaka
no journal, ,
Water in the primary circuit of Nuclear Power Plants (NPPs) decomposes by radiolysis, then oxidants such as hydrogen peroxide and oxygen are generated as a result. Hydrogen peroxide is one of the major factor for initiation and propagation of stress corrosion cracking (SCC) in structural materials, hence in-situ monitoring of hydrogen peroxide at the point of interest in irradiation field is quite important to assure the integrity of NPPs. Concentration of hydrogen peroxide in irradiation field is governed by energy deposition by neutron and -ray in which the degree of energy is different in locations, while concentration in un-irradiation area decreases due to thermal decomposition. Quantitative evaluation of hydrogen peroxide is, however, available only by analyzing sampled water at present, and therefore in-situ monitoring of hydrogen peroxide at the point of interest becomes quite important. Frequency dependent complex impedance (FDCI) analysis gives characteristics of oxide film on the materials, and it becames clear by recent activities that the low frequency semicircles in Cole-Cole plots shows linear correlation to the concentration of hydrogen peroxide. JAEA is now developing a sensor for in-situ monitoring of hydrogen peroxide applicable to irradiation environment by applying FDCI. The outline and overall schedule of the sensor development will be reported in the presentation.
-irradiation of A-, X-, Y- and mordenite type zeolites in aqueous solutionKumagai, Yuta; Kimura, Atsushi; Taguchi, Mitsumasa
no journal, ,
Zeolite minerals are suitable adsorbents for removal of radioactive cesium in water, because of their high radiation resistances. However, irradiation of zeolites results in decomposition of water adsorbed on the zeolites. Water decomposition produces hydrogen (H) and hydrogen peroxide (HO). H production has a risk of making an explosive gas mixture. HO causes corrosion of metals and alloys. Therefore, the radiation effects are required to be assessed and controlled. In this study, H and HO production by irradiation of zeolites in aqueous solution are comparatively studied among different types of zeolites, A-, X-, Y- and mordenite-types. The mixtures of the zeolites and aqueous solution were irradiated by 
Co -rays. The A-type and the X-type zeolites produced more H than the Y-type and the mordenite-type. In contrast, the HO production was inhibited by the addition of zeolites. The A-type and the X-type zeolites showed remarkable inhibition. The A-type and the X-type contains more aluminum in their frameworks than the others do. Therefore, the results suggest that aluminum sites have an important role in the reactions induced by irradiation.
Kataoka, Takahiro*; Kanzaki, Norie; Sakoda, Akihiro; Ishida, Tsuyoshi; Shuto, Hina*; Yano, Junki*; Tanaka, Hiroshi; Hanamoto, Katsumi*; Terato, Hiroaki*; Mitsunobu, Fumihiro*; et al.
no journal, ,
We have reported that radon inhalation activates antioxidative functions in mouse organs. These activation inhibits reactive oxygen species (ROS) induced oxidative stresses. Activation of antioxidative functions induced by radon inhalation probably due to the production of a small quantity of ROS. However, there were no reports on this mechanism. In this study, we evaluated hydrogen peroxide induced oxidative stress by radon inhalation in mouse organs. That is, mice inhaled radon at a concentration of 1 kBq/m
or 10 kBq/m for 24 hours. Results showed that radon inhalation increased hydrogen peroxide in liver and lung by 20%. On the other hand, hydrogen peroxide in heart decreased by 20%. This is probably due to total glutathione reacts with hydrogen peroxide. These findings suggest that radon inhalation produces a small quantity of hydrogen peroxide, which is ROS, in mouse organs. However, antioxidative related substances, which are catalase and total glutathione, play an important role to reduce oxidative stress.
in the presence of adsorbed phthalic acidKumagai, Yuta; Jonsson, M.*
no journal, ,
Contact of water with spent nuclear fuel is anticipated in scenarios of failure of the repository system for the direct disposal of spent fuel. Upon the direct contact of water, the UO matrix of the fuel is expected to gradually dissolve due to oxidation of uranium by the action of ionizing radiation. In this study, we examined effects of organic acid on the UO dissolution by using phthalic acid as a model compound. We investigated oxidation of UO by exposure to HO in aqueous solution containing phthalic acid. Significant adsorption of phthalic acid on UO was observed. The coverage of the surface was estimated to reach 80 %. The HO-exposure experiments revealed that adsorbed phthalic acid has no significant effect on the redox reaction by HO on the UO surface, despite the high surface density. HO oxidation of UO with adsorbed phthalic acid resulted in U dissolution to similar extents with the U dissolution measured in aqueous bicarbonate solutions.
