Miwa, Shuhei; Miyahara, Naoya; Nakajima, Kunihisa; Nishioka, Shunichiro; Suzuki, Eriko; Horiguchi, Naoki; Liu, J.; Miradji, F.; Imoto, Jumpei; Mohamad, B. A.; et al.
Proceedings of 27th International Conference on Nuclear Engineering (ICONE-27) (Internet), 8 Pages, 2019/05
We constructed the first version of fission product (FP) chemistry database named ECUME for LWR severe accident. The first version of ECUME is equipped with dataset of the chemical reactions and their kinetics constants for the reactions of cesium(Cs)-iodine(I)-boron(B)-molybdenum(Mo)-oxygen(O)-hydrogen(H) system in gas phase, the elemental model for the high temperature chemical reaction of Cs with stainless steel, and thermodynamic data for CsBO vapor species and solids of CsSiO and CsFeSiO. The ECUME will provide more accurate estimation of Cs distribution due to the evaluation of effects of interaction with BWR control material B and stainless steel on Cs behavior in the Fukushima Daiichi Nuclear Power Station.
Watanabe, Kosuke*; Matsuda, Shohei; Cuevas, C. A.*; Saiz-Lopez, A.*; Yabushita, Akihiro*; Nakano, Yukio*
ACS Earth and Space Chemistry (Internet), 3(4), p.669 - 679, 2019/04
The photooxidation of aqueous iodide ions (I) at sea surface results in the emission of gaseous iodine molecules (I) into the atmosphere. It plays a certain role in the transport of iodine from ocean to the atmosphere in the natural cycle of iodine. In this study, we determined the photooxidation parameters, the molar absorption coefficient (()) and the photooxidative quantum yields (()) of I, in the range of 290-500 nm. Through the investigation of the influence of pH and dissolved oxygen (DO) on (), the subsequent emission rates of I following the photooxidation of I in deionized water solution (pH 5.6, DO 7.8 mg L) and artificial seawater solution (pH 8.0, DO 7.0 mg L) were estimated. A global chemistry-climate model employed herein to assess the I ocean emission on a global scale indicated that the photooxidation of I by solar light can enhance the atmospheric iodine budget by up to 8% over some oceanic regions.
Fukuda, Kenji; Watanabe, Yusuke; Murakami, Hiroaki; Amano, Yuki; Hayashida, Kazuki*; Aosai, Daisuke*; Kumamoto, Yoshiharu*; Iwatsuki, Teruki
JAEA-Data/Code 2018-021, 76 Pages, 2019/03
Japan Atomic Energy Agency has been investigating groundwater chemistry to understand the influence of excavation and maintenance of underground facilities as part of the Mizunami Underground Research Laboratory (MIU) Project in Mizunami, Gifu, Japan. In this report, we compiled data of groundwater chemistry and microbiology obtained at the MIU in the fiscal year 2017. In terms of ensuring traceability of data, basic information (e.g. sampling location, sampling time, sampling method and analytical method) and methodology for quality control are described.
Ishikawa, Jun; Zheng, X.; Shiotsu, Hiroyuki; Sugiyama, Tomoyuki; Maruyama, Yu
Proceedings of Asian Symposium on Risk Assessment and Management 2018 (ASRAM 2018) (USB Flash Drive), 6 Pages, 2018/10
Uchida, Shunsuke*; Hanawa, Satoshi; Naito, Masanori*; Okada, Hidetoshi*; Lister, D. H.*
Corrosion Engineering, Science and Technology, 52(8), p.587 - 595, 2017/10
Based on the relationship among ECP, metal surface conditions, exposure time and other environmental conditions, a model to evaluate the ECP and corrosion rate of steel was developed by coupling a static electrochemical analysis and a dynamic oxide layer growth analysis. Major conclusion obtained on the model are as follows. The effect of HO and O concentrations on ECP were successfully explained as the effects of oxide layer growth. Hysteresis of ECP under changes in water chemistry conditions were successfully explained with the model. Decreases in ECP due to neutron exposure were explained well by radiation-induced diffusion in the oxide layers.
Osaka, Masahiko; Miwa, Shuhei; Nakajima, Kunihisa; Di Lemma, F. G.*; Suzuki, Chikashi; Miyahara, Naoya; Kobata, Masaaki; Okane, Tetsuo; Suzuki, Eriko
JAEA-Review 2016-026, 32 Pages, 2016/12
A fundamental research program on fission product (FP) chemistry has started since 2012 for the purpose of establishment of a FP chemistry database in each region of LWR under severe accident and improvement of FP chemical models based on the database. Research outputs are reflected as fundamental knowledge to both the research and development of decommissioning of Fukushima Daiichi Nuclear Power Station (1F) and enhancement of LWR safety. Four research items have thus been established considering the specific issues of 1F and the priority in the source term research area, as follows: effects of boron (B) release kinetics and thermal-hydraulic conditions on FP behavior, cesium (Cs) chemisorption and reactions with structural materials, enlargement of a thermodynamic and thermophysical properties database for FP compounds and development of experimental and analytical techniques for the reproduction of FP behavior and for direct measurement methods of chemical form of FP compounds. In this report, the research results and progress for the year 2015 are described. The main accomplishment was the installation of a reproductive test facility for FP release and transport behavior. Moreover, basic knowledge about the Cs chemisorption behavior was also obtained. In addition to the four research items, a further research item is being considered for deeper interpretation of FP behavior by the analysis of samples outside of the 1F units.
Kido, Kentaro; Hata, Kuniki; Maruyama, Yu; Nishiyama, Yutaka; Hoshi, Harutaka*
NEA/CSNI/R(2016)5 (Internet), p.204 - 212, 2016/05
Steinegger, P.*; Asai, Masato; Dressler, R.*; Eichler, R.*; Kaneya, Yusuke*; Mitsukai, Akina*; Nagame, Yuichiro; Piguet, D.*; Sato, Tetsuya; Schdel, M.; et al.
Journal of Physical Chemistry C, 120(13), p.7122 - 7132, 2016/04
A new experimental method "vacuum chromatography" has been developed to measure adsorption enthalpy of superheavy elements, and its feasibility has been examined using short-lived thallium isotopes. The short-lived thallium isotopes were produced at the JAEA tandem accelerator. The thallium ion beam prepared with an on-line isotope separator which ionized and mass-separated the thallium isotopes was injected into an isothermal vacuum chromatography apparatus. A temperature-dependent adsorption property of thallium atom on SiO surface were measured. The adsorption enthalpy of thallium was determined to be 158 kJ/mol. The thallium is a homolog of element 113. Thus, the vacuum chromatography developed in this study enables us to perform chemical experiments for short-lived superheavy elements with half-lives of a order of one second.
Secretariat of Symposium on Advanced Photon Research
JAEA-Conf 2016-001, 53 Pages, 2016/03
The 16th Symposium on Advanced Photon Research was held at Kansai Photon Science Institute, Japan Atomic Energy Agency (JAEA-KPSI) in Kizugawa city, Kyoto on October 15 - 16, 2015. This report consists of invited and contributed papers presented at the oral and poster sessions in the Symposium.
Uchida, Shunsuke; Hanawa, Satoshi; Kysela, J.*; Lister, D. H.*
Power Plant Chemistry, 18(1), p.6 - 17, 2016/01
In order to establish reliable NPP operation, each plant requires its own unique optimal water chemistry control based on careful consideration of its system, materials and operational history. Electrochemistry is one of key issues that determine corrosion related problems, e.g., FAC. Based on the relationships among ECP, metal surface conditions and exposure time, a model to evaluate ECP and corrosion rate of steel was developed by coupling an electrochemical model and an oxide layer growth model. Major conclusions are as follows. (1) The effects of water chemistry improvement and mass transfer coefficients due to local flow velocity on FAC wall thinning rate and ECP could be evaluated with the proposed model. (2) The effects of HO and O concentrations on ECP were evaluated with the model. Exposure time dependent ECPs were also explained as the effects of oxide film growth on the specimens. (3) Decreases in ECP due to neutron exposure were explained by radiation-induced diffusion in the oxide layers.
Sasamoto, Hiroshi; Yamamoto, Nobuyuki; Miyakawa, Kazuya; Mizuno, Takashi
JAEA-Data/Code 2014-033, 43 Pages, 2015/03
Development of technologies to investigate properties (conditions) of deep geological environment and models development of geological environment have been pursued in "Geoscientific Research" in the Horonobe underground research laboratory (Horonobe URL) project. A geochemical model of groundwater evolution which is a part of geological environment model requires the data of groundwater chemistry around the Horonobe URL for the development. This report summarizes the data obtained for 3 years (i.e., from the fiscal year 2011 to 2013), especially for the results for measurement of physico-chemical parameters and analysis of groundwater chemistry, in the Horonobe URL project.
Sasaki, Ichiro; Hanaoka, Hirofumi*; Yamada, Keiichi*; Watanabe, Shigeki; Sugo, Yumi; Ohshima, Yasuhiro; Suzuki, Hiroyuki; Ishioka, Noriko
Peptide Science 2014, p.257 - 260, 2015/03
Kim, S.-Y.; Asakura, Toshihide; Morita, Yasuji; Ikeda, Yasuhisa*
Journal of Alloys and Compounds, 408-412, p.1291 - 1295, 2006/02
The electrochemical reactions of UO(-diketonato)DMF, UO(trop)DMF and UO(sap)(DMF), (DMF = N,N-dimethylformamide, -diketonate = thenoyltrifluoroacetonate (ttfa), benzoyltrifluoroacetonate (btfa), and dibenzoylmethanate(dbm), trop = tropolonate, and sap = 2-salicylidenaminophenolate) complexes in DMF solution containing tetrabutyl ammonium perchlorate as a supporting electrolyte have been studied with cyclic voltammetry. These uranyl(VI) complexes were found to be quasi-reversibly reduced to U(V) species. The formal redox potentials (E, . ferrocene/ferrocenium) for U(VI)/U(V) couples were determined to be -1.18 V for UO(ttfa)DMF, -1.18 V for UO(btfa)DMF, -1.46 V for UO (dbm)DMF, -1.46 V for UO(trop)DMF, and -1.59 V for UO(sap)(DMF).
Kim, S.-Y.; Asakura, Toshihide; Morita, Yasuji
Radiochimica Acta, 93(12), p.767 - 770, 2005/12
Electrochemical and spectroelectrochemical has been used to investigate the behaviour of Neptunium (VI) in concentration 1-8 M HNO solutions. The electrochemical reactions of Np(VI) ions were found to occur quasi-reversibly. The formal redox potentials (E) for Np(VI)/Np(V) couples were determined to be +0.906, +0.908, +0.909, +0.902, +0.896, +0.895, +0.888, and +0.884 V (vs. Ag/AgCl) for Np(VI) ions in 1, 2, 3, 4, 5, 6, 7, 8 M HNO solutions, respectively. The reduction processes of Np(VI) ions were followed spectroelectrochemically by using an optical transparent thin layer electrode cell. It was found that the absorption spectra measured at the applied potentials from +1.10 to +0.60 V versus Ag/AgCl reference electrode redox couple for Np(VI) in HNO solution have clear isosbestic points. These results indicate that the reduction product of Np(VI) is Np(V), which is considerably stable in HNO solution.
Sakaba, Nariaki; Hirayama, Yoshiaki*
Proceedings of International Conference on Nuclear Energy System for Future Generation and Global Sustainability (GLOBAL 2005) (CD-ROM), 6 Pages, 2005/10
The high-temperature gas-cooled reactor (HTGR) is capable of producing a massive quantity of hydrogen with no carbon dioxide emission during its production by a thermo chemical IS (Iodine-Sulphur) process. The HTTR (High Temperature Engineering Test Reactor), which is the first high-temperature gas-cooled reactor in Japan, will be connected to some heat utilization system in the near future. The thermo chemical IS process is one of the progressive candidates. The metallic material of the heat transfer tube of the intermediate heat exchanger (IHX) and liner in the concentric hot gas duct in the HTTR-IS system, which allows usage in high-temperature conditions, is the nickel-based high-temperature alloy Hastelloy XR. Since the coolant helium contains small amounts of impurities, it is necessary to control the chemical composition in order to minimize corrosion of the Hastelloy XR. Major corrosion phenomena of the Hastelloy XR are carburization, decarburization, oxidation, and carbon deposition depending upon the particular gas composition and its temperature. The carburization and decarburization phenomena can be restricted by controlling the carbon activity and oxygen partial pressure. This paper describes the effect of each coolant impurity for the carburization and decarburization. Also a chemical composition limit was evaluated to avoid the Hastelloy XR corrosion.
Kim, S.-Y.; Asakura, Toshihide; Morita, Yasuji
JAERI-Conf 2005-007, p.341 - 344, 2005/08
Electrochemistry has been used to investigate the behavior of plutonium(IV) in 1-7 M HNO solutions. These Pu(IV) complexes were found to be reduced quasi-reversibly to Pu(III) species. The formal redox potentials (E) for Pu(IV)/Pu(III) couples were determined to be +0.721, +0.712, +0.706, +0.705, +0.704, 0.694, and +0.696 V (vs. Ag/AgCl(SSE)) for Pu(IV) complexes in 1, 2, 3, 4, 5, 6, 7 M HNO solutions, respectively. These results indicate that the reduction product of Pu(IV) is Pu(III), which is considerably stable in HNO solution.
Sakaba, Nariaki; Tachibana, Yukio; Nakagawa, Shigeaki; Hamamoto, Shimpei
Transactions of 18th International Conference on Structural Mechanics in Reactor Technology (SMiRT-18), p.4499 - 4511, 2005/08
Safety demonstration tests using the HTTR are now underway in order to verify the inherent safety features and to improve the safety design and evaluation technologies for HTGRs, as well as to contribute to research and development for the VHTR, which is one of the Generation IV reactor candidates. The coolant flow reduction test by running down gas circulators, which is one of the safety demonstration tests, is a simulation test of anticipated transients without scram. During the coolant flow reduction test, temperature of the high-temperature helium components and chemistry in the primary circuit are changed rapidly. This paper describes the structural integrity assessments of helium components, e.g. helium pipes, heat exchangers, during the coolant flow reduction test. From the result of this evaluation, it was found that the helium components were kept their structural integrity during temperature and chemistry transient condition in the coolant flow reduction test from the reactor power at 30%. It was also confirmed by this assessment that the coolant flow reduction test will be able to perform with its enough safety margins from the reactor power at 100%.
Ishii, Tetsuro; Asai, Masato; Chimi, Yasuhiro
JAERI-Conf 2005-006, 144 Pages, 2005/07
The facility of the JAERI-Tokai tandem accelerator and its booster has been contributing to advancing heavy-ion sciences in the fields of nuclear physics, nuclear chemistry, atomic and solid-state physics and materials science, taking advantage of its prominent performance of heavy-ion acceleration. This facility was recently upgraded by changing the acceleration tubes and installing an ECR ion-source at the terminal. The radioactive nuclear beam facility (TRIAC) was also installed by the JAERI-KEK joint project. On this occasion, this meeting was held in order to provide a new step for the advancement of heavy-ion science, and to exchange information on recent activities and future plans using the tandem facility as well as on promising new experimental techniques. This meeting was held at Tokai site of JAERI on January 6th and 7th in 2005, having 24 oral presentations, and was successfully carried out with as many as 90 participants and lively discussions among scientists from all the fields of heavy-ion science.
Sakaba, Nariaki; Tachibana, Yukio; Onuki, Kaoru; Komori, Yoshihiro; Ogawa, Masuro
Nuclear Engineering International, 50(612), p.20 - 22, 2005/07
The HTTR (High Temperature Engineering Test Reactor) at Japan Atomic Energy Research Institute's Oarai Research Establishment attained its maximum reactor-outlet coolant temperature of 950C in April 2004 and ready to connect nuclear heat for industrial applications. The hydrogen production system by thermochemical water-splitting Iodine Sulphur cycle is also developing and succeeded to produce 30 normal L/h hydrogen in a closed cycle in June 2004.
Kuznetsov, S. A.*; Hayashi, Hirokazu; Minato, Kazuo; Gaune-Escard, M.*
Journal of the Electrochemical Society, 152(4), p.C203 - C212, 2005/04
The electrochemical behavior of UCl and UCl dissolved in LiCl-KCl eutectic melt was studied at 723-823 K. Electroreduction of U(IV) in LiCl-KCl melt occurs via two successive steps involving transfer of one and three electrons. The diffusion coefficients of U(IV) and U(III) ions were determined by linear sweep voltammetry, chronopotentiometry, and chronoamperometry. The formal standard potential of EU(IV)/U(III), EU(IV)/U, and EU(III)/U were determined and some thermodynamic properties of UCl and UCl dissolved in LiCl-KCl eutectic melt were calculated. Influence of oxide ions on electrochemical behavior was also studied.