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Onodera, Naoyuki; Idomura, Yasuhiro; Hasegawa, Yuta; Shimokawabe, Takashi*; Aoki, Takayuki*
Keisan Kogaku Koenkai Rombunshu (CD-ROM), 27, 4 Pages, 2022/06
We have developed a wind simulation code named CityLBM to realize wind digital twins. Mesoscale wind conditions are given as boundary conditions in CityLBM by using a nudging data assimilation method. It is found that conventional approaches with constant nudging coefficients fail to reproduce turbulent intensity in long time simulations, where atmospheric stability conditions change significantly. We propose a dynamic parameter optimization method for the nudging coefficient based on a particle filter. CityLBM was validated against plume dispersion experiments in the complex urban environment of Oklahoma City. The nudging coefficient was updated to reduce the error of the turbulent intensity between the simulation and the observation, and the atmospheric boundary layer was reproduced throughout the day.
Yomogida, Takumi; Saeki, Morihisa*; Morii, Shiori; Oba, Hironori*; Kitatsuji, Yoshihiro
Analytical Sciences, 37(12), p.1843 - 1846, 2021/12
Times Cited Count：0 Percentile：0(Chemistry, Analytical)In this study, we developed a simple and one-step Pd separation technique based on photoreduction with Xe lamp irradiation for the determination of 
Pd in highly radioactive samples. A simulated high-level radioactive liquid wastes (HLLW) solution, which consists of 14 major elements (Rb, Sr, Zr, Mo, Ru, Rh, Pd, Cs, Ba, La, Ce, Pr, Nd, Sm) in a 3 mol L
HNO
solution, was used to evaluate the separation performance. The Pd precipitate were formed by Xe lamp irradiation and recovered by centrifugation. The results showed that the recovery of Pd from a simulated HLLW solution depend on the irradiation time and concentration of ethanol. By optimizing the conditions at photo irradiation, the Pd recovery from the simulated HLLW solution reached up to 50 %, while 99.5 % of the other 13 elements were separated. The Pd precipitate could be separated from the elements that are the main source of radioactivity (Sr, Cs, and Ba) and the source of spectral interference for the determination of Pd (Zr, and Ru). These results indicate that selective separation of Pd is achieved with the proposed method, showing the applicability of the proposed separation technique to HLLW samples.
Takahashi, Tomoyuki*; Uchida, Shigeo*; Takeda, Seiji; Nakai, Kunihiro*
KURNS-EKR-11, p.97 - 102, 2021/03
This paper outlines the status of IAEA database compilation for migration parameters depending elements in a biosphere such as soil-to-plant transfer factor and bioconcentration factor of marine products, and the status of utilization of the database in dose evaluation of radioactive waste disposal in Japan. Additionally, in the case of applying a new database to the dose evaluation for future radioactive waste disposal in a specific area. We summarized the opinions of specialists and result of general discussion about future strategies to make a new database for their parameters, perspectives to be considered in it, issues, etc.
Suzudo, Tomoaki; Takamizawa, Hisashi; Nishiyama, Yutaka; Caro, A.*; Toyama, Takeshi*; Nagai, Yasuyoshi*
Journal of Nuclear Materials, 540, p.152306_1 - 152306_10, 2020/11
Times Cited Count：9 Percentile：75.12(Materials Science, Multidisciplinary)Spinodal decomposition in thermally aged Fe-Cr alloys leads to significant hardening, which is the direct cause of the so-called 475C-embrittlement. To illustrate how spinodal decomposition induces hardening by atomistic interactions, we conducted a series of numerical simulations as well as reference experiments. The numerical results indicated that the hardness scales linearly with the short-range order (SRO) parameter, while the experimental result reproduced this relationship within statistical error. Both seemingly suggest that neighboring Cr-Cr atomic pairs essentially cause hardening, because SRO is by definition uniquely dependent on the appearance probability of such pairs. A further numerical investigation supported this notion, as it suggests that the dominant cause of hardening is the pinning effect of dislocations passing over such Cr-Cr pairs.
, an iodine source for the immobilisation of radioiodineJohnstone, E. V.*; Bailey, D. J.*; Lawson, S.*; Stennett, M. C.*; Corkhill, C. L.*; Kim, M.*; Heo, J.*; Matsumura, Daiju; Hyatt, N. C.*
RSC Advances (Internet), 10(42), p.25116 - 25124, 2020/07
Times Cited Count：3 Percentile：15.14(Chemistry, Multidisciplinary)Kato, Tomoko; Fukaya, Yukiko*; Sugiyama, Takeshi*; Nakai, Kunihiro*; Oda, Chie; Oi, Takao
JAEA-Data/Code 2019-002, 162 Pages, 2019/03
JAEA-Data-Code-2019-002.pdf:2.78MB
The radioactive waste generated from Fukushima Daiichi nuclear power station (FDNPS) accident have features such as wide range of radioactivity level (from low to high) and huge amount etc. It would be necessary for the waste from the FDNPS accident to develop suitable disposal concept and to be disposed safely and reasonably. When considering such appropriate disposal concepts in site-generic phase, it is necessary to appropriately develop models and parameters depending on the disposal concepts, such as disposal depth and specification of engineered barrier. In addition, it is desirable to evaluate the safety of repository with common models and parameters independent on the disposal concepts. In the safety assessment of disposal, it is useful to show the difference in performance of repository with "dose" as an indicator of safety assessment. Biosphere model and parameter set and flux-to-dose conversion factors calculated using them are originally dependent on the disposal concepts. However, the biosphere models and the parameter set in safety assessment of near-surface disposal, sub-surface disposal and geological disposal are prepared in each case, and are different according to the age and purpose of the discussion. In this study, an example of biosphere model and parameter-set of groundwater sceinario commonly applicable to various disposal concepts were shown, to calculate flux-to-dose conversion factors, as common indicators independent to disposal concept. And, a set of flux-to-dose conversion factors was also calculated by using the commonly available biosphere model and parameter set. By applying the flux-to-dose conversion factors, it is possible to compare the performance of disposal concepts to the waste generated from FDNPS accident, focusing on the parts depending on the disposal concepts.
Saeki, Morihisa*; Matsumura, Daiju; Yomogida, Takumi; Taguchi, Tomitsugu*; Tsuji, Takuya; Saito, Hiroyuki*; Oba, Hironori*
Journal of Physical Chemistry C, 123(1), p.817 - 824, 2019/01
Times Cited Count：14 Percentile：53.24(Chemistry, Physical)Reaction kinetics of laser-induced particle formation in an aqueous solution of PdCl
was investigated by transmission electron microscope (TEM) and dispersive X-ray absorption fine structure (DXAFS). The Pd particle was generated by irradiation of nanosecond pulsed 266-nm laser. The TEM observation showed dependence of the particle size on the laser fluence and promotion of the particle growth by irradiation of high-fluence laser. The DXAFS data give us the Pd
concentration. Temporal changes of the Pd concentration analyzed based on Finke-Watzky two step mechanism. The analysis elucidates that the laser photon contributes to the reduction of the PdCl ion by the one-photon process and to the autocatalytic growth of the Pd particles by the multi-photon process.
Saeki, Morihisa*; Asai, Shiho; Oba, Hironori*
Bunseki, 2018(4), p.138 - 143, 2018/04
Platinum group metal (PGM) has attracted much attention in light of increasing demands in the industrial sector. A wide variety of techniques specialized for PGM separation, such as, solvent extraction, solid phase extraction, and molten salt electrolysis have been developed so far. Among such techniques, a newly developed separation technique based on laser-induced particulate formation can be a promising alternative to conventional ones. It enables non-contact and highly-selective separation with a simple operation. In this review, the research history and the basic mechanism of laser-induced particulate formation were outlined. Several applications were also mentioned, focusing on our latest research progress which achieved a world first quantitation of radioactive palladium in a spent nuclear fuel sample.
Mezawa, Tetsuya; Mochizuki, Akihito; Miyakawa, Kazuya; Sasamoto, Hiroshi
JAEA-Data/Code 2018-001, 55 Pages, 2018/03
JAEA-Data-Code-2018-001.pdf:10.63MB
JAEA-Data-Code-2018-001-appendix(CD-ROM).zip:8.57MB
Japan Atomic Energy Agency has been conducting "geoscientific study" and "research and development on geological disposal" in the Horonobe Underground Research Laboratory (URL) for safe geological disposal of high-level radioactive waste. Geochemical parameters of groundwater pressure, pH, and oxidation-reduction potential in the deep groundwater has been continuously monitored with monitoring systems which were developed in the Horonobe URL Project. This report presents the physico-chemical parameters of groundwater which have been obtained by the monitoring systems installed at the 140 m, 250 m and 350 m gallery. The data obtained until March 31, 2017 was summarized along with related information such as the specifications of boreholes and the excavation of the URL.
Takada, Hiroshi
JAEA-Conf 2017-001, p.51 - 56, 2018/01
A pulsed spallation neutron source of Japan Proton Accelerator Research Complex (J-PARC) is aimed at promoting a variety of cutting-edge materials researches at state-of-the-art neutron instruments with neutrons generated by a 3-GeV proton beam with a power of 1-MW at a repetition rate of 25 Hz. In 2015, for the first time it received 1-MW equivalent proton beam pulse, and the beam power for user program was ramped up to 500 kW. The moderator system of the neutron source was optimized to use (1) 100% para-hydrogen for increasing pulse peak intensity with decreasing pulse tail, (2) cylindrical shape with 14 cm diam. 
12 cm long for providing high intensity neutrons to wide neutron extraction angles of 50.8 degrees, (3) neutron absorber made from Ag-In-Cd alloy to make pulse widths narrower and pulse tails lower. As a result, it gives highest intensity pulsed neutrons per incident proton in the world. Towards the goal to achieve the target operation at 1-MW for 5000 h in a year, efforts to mitigate cavitation damages at the target vessel front with injecting gas micro-bubbles into the mercury target are under way. Also, improvement of structural target vessel design is an urgent issue since there was failure twice at the water shroud of the mercury target due to the thermal stress during operating periods at 500 kW in 2015.
Narita, Hirokazu*; Maeda, Motoki*; Tokoro, Chiharu*; Suzuki, Tomoya*; Tanaka, Mikiya*; Motokawa, Ryuhei; Shiwaku, Hideaki; Yaita, Tsuyoshi
Analytical Sciences, 33(11), p.1305 - 1309, 2017/11
Times Cited Count：11 Percentile：40.32(Chemistry, Analytical)Saeki, Morihisa*; Taguchi, Tomitsugu*; Oba, Hironori*; Matsumura, Daiju; Tsuji, Takuya; Yomogida, Takumi
Denki Gakkai Kenkyukai Shiryo, Denshi Zairyo Kenkyukai (EFM-17-010
021), p.15 - 18, 2017/09
Irradiation of nanosecond pulsed UV laser into a solution of palladium ion leads to formation of palladium particles with sub-micron size particles by time-resolved X-ray absorption spectroscopy.
Morita, Yasuji; Yamagishi, Isao
JAEA-Research 2017-006, 27 Pages, 2017/06
JAEA-Research-2017-006.pdf:1.83MB
Separation of Pd by extraction with 5,8-diethyl-7-hydroxy-6-dodecanone oxime (DEHDO) was examined by batch and continuous tests for the purpose of developing Pd separation process. Batch extraction tests using n-dodecane solution of DEHDO revealed that Pd, Zr and Mo were extracted from simulated high-level radioactive liquid wastes (HLLW) and other elements were not, and also showed that the extraction rate was a little slow and a white precipitate appeared in the aqueous phase but its formation could be avoided by raising temperature. The extracted Pd was found to be back-extracted with sodium nitrite. In the continuous extraction tests with simulated HLLW without Zr and Mo, about 98% of Pd were extracted with DEHDO-n-dodecane and 95% of the extracted Pd were back-extracted with sodium nitrite and nitric acid. Continuous extraction test with simulated HLLW with Zr and Mo showed the possibility of the simultaneous separation of Pd and Mo by DEHDO extraction.
X-ray absorption spectroscopy study on water formation reaction of palladium metal nanoparticle catalystsMatsumura, Daiju; Taniguchi, Masashi*; Tanaka, Hirohisa*; Nishihata, Yasuo
International Journal of Hydrogen Energy, 42(11), p.7749 - 7754, 2017/03
Times Cited Count：5 Percentile：13.92(Chemistry, Physical)O studied by time-resolved XAFS using dispersive opticsMatsumura, Daiju; Okajima, Yuka*; Nishihata, Yasuo
Journal of Physics; Conference Series, 712(1), p.012042_1 - 012042_4, 2016/06
Times Cited Count：0 Percentile：0.03(Physics, Applied)Choi, B.; Nishida, Akemi; Nakajima, Norihiro
Proceedings of 24th International Conference on Nuclear Engineering (ICONE-24) (DVD-ROM), 7 Pages, 2016/06
Research and development of three-dimensional vibration simulation technologies for nuclear facilities have been promoted in the Center for Computational Science and e-Systems of the Japan Atomic Energy Agency (JAEA). A seismic intensity of upper 5 was observed in the area of High-Temperature Engineering Test Reactor (HTTR) at the Oarai Research and Development Center of the JAEA during the 2011 Tohoku earthquake. In this paper, we report a parametric study of seismic response analyses of this earthquake using three-dimensional finite element models of the HTTR building with various uncertainty parameters (e.g. soil-structure interaction effects, soil properties). By examining the variation of the response result against the uncertainty parameters, we obtained a knowledge, which is essential for constructing a valid three-dimensional finite element model.
Tsuchiya, Harufumi; Harada, Hideo; Koizumi, Mitsuo; Kitatani, Fumito; Takamine, Jun; Kureta, Masatoshi; Iimura, Hideki; Kimura, Atsushi; Becker, B.*; Kopecky, S.*; et al.
Nuclear Instruments and Methods in Physics Research A, 767, p.364 - 371, 2014/12
Times Cited Count：10 Percentile：60.73(Instruments & Instrumentation)The impact of systematic effects on the areal density derived from a neutron resonance transmission analysis (NRTA) is investigated by measurements at the time-of-flight facility GELINA. The experiments were carried out at a 25 m station using metallic natural Cu discs with different thicknesses. To derive the areal density from a fit to the experimental transmission, the resonance shape analysis code REFIT was used. Large bias effects were observed using recommended resonance parameters. Therefore, neutron resonance parameters, in particular resonance energies and neutron widths, were derived from the transmission data obtained with a 0.25 mm thick Cu metallic sample. These parameters were used to study the impact of the resonance strength and sample thickness, on the accuracy of the areal density derived by NRTA.
Matsukawa, Makoto; Tamai, Hiroshi; Fujita, Takaaki; Kizu, Kaname; Sakurai, Shinji; Tsuchiya, Katsuhiko; Kurita, Genichi; Morioka, Atsuhiko; Ando, Toshinari; Miura, Yushi
IEEE Transactions on Applied Superconductivity, 16(2), p.914 - 917, 2006/06
Times Cited Count：4 Percentile：29.22(Engineering, Electrical & Electronic)no abstracts in English
Abe, Hiroshi; Morimoto, Ryo*; Sato, Fumiatsu*; Azuma, Yorito*; Uchida, Hirohisa*
Journal of Alloys and Compounds, 404-406, p.288 - 292, 2005/12
Times Cited Count：7 Percentile：51.6(Chemistry, Physical)The effect of ion irradiation on the rate of electrochemical hydriding rate of palladium (Pd) was investigated. In this study, ion irradiation onto the Pd surface was made with H
, He, Ar and N in the acceleration energy range from 30 to 350 keV, and in the ion dose up to 1 10
cm
. As the ion dose was increased, the initial rate of hydriding of Pd was increased. The ion irradiatiion treatment of the surface of a metal induces high concentrations of vacancy. The increased hydriding rate may be caused by the induction of high concentration of vacancy whichi traps hydrogen atoms, and this seems to accelerate the rates of hydride nucleation and growth in the surface. The ion irradiation was found as an effective way to enhance the rate of the initial activation of Pd in the electrochemical hydriding process.
Yamaguchi, Tetsuji; Minase, Naofumi; Iida, Yoshihisa; Tanaka, Tadao; Nakayama, Shinichi
JAERI-Conf 2005-007, p.150 - 155, 2005/08
no abstracts in English
