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Ono, Ayako; Yamashita, Susumu; Sakashita, Hiroto*; Suzuki, Takayuki*; Yoshida, Hiroyuki
Proceedings of 13th International Topical Meeting on Nuclear Reactor Thermal-Hydraulics, Operation and Safety (NUTHOS-13) (Internet), 12 Pages, 2022/09
Japan Atomic Energy Agency is developing the computational fluid dynamics code, JUPITER, based on the volume of fluid (VOF) method to analyze detailed thermal-hydraulics in a reactor. The detailed numerical simulation of boiling from a heating surface needs a substantial computational cost to resolve the microscale thermal-hydraulic phenomena such as the bubble generation from a cavity and evaporation of a micro-layer. This study developed the simplified boiling model from the heating surface to reduce the computational cost, which will apply to the detailed simulation code based on the surface tracking method such as JUPITER. We applied the simplified boiling model to JUPITER, and compared the simulation results with the experimental data of the vertical heating surface in the forced convection. We confirmed the degree of their reproducibility, and the issues to be modified were extracted.
Ono, Ayako; Yamashita, Susumu; Sakashita, Hiroto*; Suzuki, Takayuki*; Yoshida, Hiroyuki
Dai-26-Kai Doryoku, Enerugi Gijutsu Shimpojiumu Koen Rombunshu (Internet), 4 Pages, 2022/07
JAEA is implementing a simulation of a two-phase flow in the reactor core by TPFIT and JUPITER which are developed by JAEA based on the surface tracking method. However, it is impossible to simulate a boiling on the heating surface in the large-scale domain by this type of simulation method since the simulation of boiling based on the surface tracking method needs the fine mesh which sufficiently resolves the initiation of boiling. Therefore, JAEA started to develop the simplified boiling model applied for the two-phase flow in the fuel assemblies. In this study, the simulation results of the convection boiling on a vertical heating surface and the comparison between the simulation results and experimental results are shown.
Senzaki, Tatsuya; Arai, Yoichi; Yano, Kimihiko; Sato, Daisuke; Tada, Kohei; Ogi, Hiromichi*; Kawanobe, Takayuki*; Ono, Shimpei; Nakamura, Masahiro; Kitawaki, Shinichi; et al.
JAEA-Testing 2022-001, 28 Pages, 2022/05
JAEA-Testing-2022-001.pdf:2.33MB
In preparation for the decommissioning of Laboratory B of the Nuclear Fuel Cycle Engineering Laboratory, the nuclear fuel material that had been stored in the glove box for a long time was moved to the Chemical Processing Facility (CPF). This nuclear fuel material was stored with sealed by a polyvinyl chloride (PVC) bag in the storage. Since it was confirmed that the PVC bag swelled during storage, it seems that any gas was generated by radiolysis of the some components contained in the nuclear fuel material. In order to avoid breakage of the PVC bag and keep it safety for long time, we began the study on the stabilization treatment of the nuclear fuel material. First, in order to clarify the properties of nuclear fuel material, radioactivity analysis, component analysis, and thermal analysis were carried out. From the results of thermal analysis, the existence of organic matter was clarified. Then, ion exchange resin with similar thermal characteristics was selected and the thermal decomposition conditions were investigated. From the results of these analyzes and examinations, the conditions for thermal decomposition of the nuclear fuel material contained with organic matter was established. Performing a heat treatment of a small amount of nuclear fuel material in order to confirm the safety, after which the treatment amount was scaled up. It was confirmed by the weight change after the heat treatment that the nuclear fuel material contained with organic matter was completely decomposed.
Ono, Ayako; Yamashita, Susumu; Suzuki, Takayuki*; Yoshida, Hiroyuki
Proceedings of 19th International Topical Meeting on Nuclear Reactor Thermal Hydraulics (NURETH-19) (Internet), 16 Pages, 2022/03
JAEA is developing the methodology to predict the critical heat flux based on a mechanism in order to reduce the cost for full mock-up test. The evaluation method based on a mechanism is expected to be able to predict in the wide range of parameter under the unexpected conditions including the severe accident. In this study, the JUPITER code developed by JAEA is examined to apply for the two-phase flow simulation of LWR fuel assembly with the spacer grid. The benchmark data of single-phase flow in the bundle with the spacers by KAERI were used to validate the simulation result by JUPITER. Moreover, the single-phase flow simulation was conducted by another simulation method, STAR-CCM+, as a supplemental analysis to consider the effect of the different simulation methods. Finally, the two-phase flow simulation for the bundle with the spacer was conducted by JUPITER. The effect of the spacer with a vane on the bubble behavior is discussed.
MnGa thin films underneath a protection layerKono, Takashi*; Kakoki, Masaaki*; Yoshikawa, Tomoki*; Wang, X.*; Sumida, Kazuki; Muro, Takayuki*; Goto, Kazuki*; Sakuraba, Yuya*; Umetsu, Rie*; Kimura, Akio*
Physical Review B, 104(19), p.195112_1 - 195112_8, 2021/11
Times Cited Count：0 Percentile：9.64(Materials Science, Multidisciplinary)Angle-resolved photoelectron spectroscopy utilizing soft X-ray synchrotron radiation was applied to Heusler-type CoMnGa thin films that have a 1-nm Al capping layer. The bulk Fermi surfaces and band structures varied along the out-of-plane momentum, stemming from the three-dimensional crystal structure, in the absence of any in situ surface treatment. In addition, there were characteristic intersecting bands (Weyl cones), with crossing points near the Fermi level, which were consistent with computed results. The Weyl cones are of bulk origin and are responsible for the high anomalous Nernst and the anomalous Hall coefficients. A close comparison of the experimental band structures in CoMnGe and CoMnGa indicated that the rigid band picture is valid in both alloys and that fine carrier tuning is possible by replacing Ga with Ge to improve the anomalous conductivity.
Yamashita, Takayuki*; Koga, Norimitsu*; Kawasaki, Takuro; Morooka, Satoshi; Tomono, Shohei*; Umezawa, Osamu*; Harjo, S.
Materials Science & Engineering A, 819, p.141509_1 - 141509_10, 2021/07
Times Cited Count：11 Percentile：80.8(Nanoscience & Nanotechnology)Shobu, Takahisa; Shiro, Ayumi*; Kono, Fumiaki*; Muramatsu, Toshiharu; Yamada, Tomonori; Naganuma, Masayuki; Ozawa, Takayuki
Quantum Beam Science (Internet), 5(2), p.17_1 - 17_9, 2021/06
The automotive industries employ laser beam welding because it realizes a high energy density without generating irradiation marks on the opposite side of the irradiated surface. Typical measurement techniques such as strain gauges and tube X-rays cannot assess the localized strain at a joint weld. Herein high-energy synchrotron radiation X-ray diffraction was used to study the internal strain distribution of laser lap joint PNC-FMS steels (2- and 5-mm thick) under loading at a high temperature. As the tensile load increased, the local tensile and compressive strains increased near the interface. These changes agreed well with the finite element analysis results. However, it is essential to complementarily utilize internal defect observations by X-ray transmission imaging because the results depend on the defects generated by laser processing.
Yamashita, Takayuki; Tomono, Shohei*; Morooka, Satoshi; Harjo, S.; Kawasaki, Takuro; Nameki, Tatsuya*; Koga, Norimitsu*; Umezawa, Osamu*
JPS Conference Proceedings (Internet), 33, p.011064_1 - 011064_6, 2021/03
4 simulated bundleOno, Ayako; Yamashita, Susumu; Suzuki, Takayuki*; Yoshida, Hiroyuki
Mechanical Engineering Journal (Internet), 7(3), p.19-00583_1 - 19-00583_12, 2020/06
JAEA is implementing the 3D detailed nuclear-thermal-coupled analysis code to analyze the transition state of the core and to reduce the likelihood of the design. In the development plan, the computational fluid dynamics code based on the VOF method, JUPITER, is applied for TH part of the 3D detailed nuclear-thermal-coupled analysis code.
Kumada, Takayuki; Oba, Yojiro; Motokawa, Ryuhei; Morooka, Satoshi; Tominaga, Aki; Tanida, Hajime; Shobu, Takahisa; Konno, Azusa; Owada, Kenji*; Ono, Naoko*; et al.
Journal of Nuclear Materials, 528, p.151890_1 - 151890_7, 2020/01
Times Cited Count：1 Percentile：13.39(Materials Science, Multidisciplinary)We have developed an anomalous small-angle X-ray scattering (ASAXS) diffractometer in SPring-8 to investigate irradiation-induced nanostructural change in ion-beam irradiated stainless steel. A thermally-aged MA956 stainless steel sample displays power-law scattering that follows the Porod law at the magnitude of scattering vector, Q, below 0.5 nm
and an overlapped shoulder around 0.7 nm. After the ion-beam irradiation, the intensity of the shoulder remained unchanged, whereas that of the power-law scattering nearly doubled. This result indicates that none of the structural parameters of the Cr-rich nanoprecipitates, such as the number density, size, and interface roughness, were changed by the irradiation.
MnGe revealed by resonant photoelectron spectroscopyKono, Takashi*; Kakoki, Masaaki*; Yoshikawa, Tomoki*; Wang, X.*; Sumida, Kazuki*; Miyamoto, Koji*; Muro, Takayuki*; Takeda, Yukiharu; Saito, Yuji; Goto, Kazuki*; et al.
Physical Review B, 100(16), p.165120_1 - 165120_6, 2019/10
Times Cited Count：4 Percentile：23.45(Materials Science, Multidisciplinary)Ono, Masato; Kozawa, Takayuki; Fujimoto, Nozomu*
JAEA-Technology 2019-012, 15 Pages, 2019/09
JAEA-Technology-2019-012.pdf:2.83MB
The High Temperature Engineering Test Reactor has a neutron source of 
Cf to start up the reactor and to confirm count rates of wide range monitors. The half-life of Cf is short, about 2.6 years, so it is necessary to replace at an appropriate time. In order to estimate the period to replace, it is necessary to consider not only the half-life but also the fluctuation of the count rate of the wide range monitor to prevent alarm. For that reason, the method has been derived to predict a minimum count rate from relationship between the count rate and the standard deviation of the count rate of the wide range monitors. As a result of predicting the count rate using this method, it was found that the minimum count rate reaches to 3.0cps in 2022 and 1.5 cps in 2024. Therefore, it is necessary to exchange Cf by 2024.
Ono, Ayako; Yamashita, Susumu; Suzuki, Takayuki*; Yoshida, Hiroyuki
Proceedings of 18th International Topical Meeting on Nuclear Reactor Thermal Hydraulics (NURETH-18) (USB Flash Drive), p.666 - 677, 2019/08
An evaluation methodology of critical heat fluxes (CHFs) based on a mechanism for fuel assemblies in light water reactors (LWRs) is needed in order to design and evaluate the safety for the fuel assemblies in LWRs. In our study, the numerical simulation with surface-tracking will be applied for the two-phase flow in fuel assemblies in order to obtain the detail data relating to the size and velocity of bubbles in the subchannel, which is needed to predict the CHF based on the mechanism. In this study, the numerical simulation of two-phase flow in 44 bundle was implemented by using JUPITER in order to establish the evaluation method of the size and velocity of bubbles by the numerical simulation, which is the multi-physics simulation code and enable to track the gas-liquid surface. The simulation results are validated by the curve of flow regime for air-water under the adiabatic condition. The bubble and velocity of bubbles obtained by simulation results are analyzed.
Strasser, P.*; Abe, Mitsushi*; Aoki, Masaharu*; Choi, S.*; Fukao, Yoshinori*; Higashi, Yoshitaka*; Higuchi, Takashi*; Iinuma, Hiromi*; Ikedo, Yutaka*; Ishida, Katsuhiko*; et al.
EPJ Web of Conferences, 198, p.00003_1 - 00003_8, 2019/01
Times Cited Count：13 Percentile：99.33Nagai, Takayuki; Okamoto, Yoshihiro; Shiwaku, Hideaki; Inose, Takehiko*; Sato, Seiichi*; Hatakeyama, Kiyoshi*; Hirono, Kazuya*; Homma, Masanobu*; Kobayashi, Hiromi*; Takahashi, Tomoe*; et al.
JAEA-Research 2018-007, 87 Pages, 2018/11
JAEA-Research-2018-007.pdf:61.21MB
To select the chemical composition of a glass frit which can increase the waste content, the simulated waste glass samples prepared from a borosilicate glass frit including vanadium (V) were investigated by using Laser Ablation (LA) ICP-AES analysis, Raman spectrometry, and synchrotron XAFS measurement in this study on foundation business of the Agency for Natural Resources and Energy.
Ono, Ayako; Suzuki, Takayuki*; Yoshida, Hiroyuki
Proceedings of 12th International Topical Meeting on Nuclear Reactor Thermal-Hydraulics, Operation and Safety (NUTHOS-12) (USB Flash Drive), 9 Pages, 2018/10
The mechanism of Critical Heat Flux (CHF) remains to be clarified, even though it is important to evaluate the CHF for super high heat flux components such as light water reactors (LWRs). Some theoretical models to predict the CHF is proposed so far. A macrolayer formation model which is proposed in order to predict the CHF based on the macrolayer dryout model. In this model, it is assumed that the liquid is captured inside vapor mass at coalescence. In this study, the verification of the assumption of a macrolayer formation model by the numerical simulation of CMFD code, TPFIT, from the view point of hydrodynamics.
symmetry in CeCuGe; Soft X-ray absorption and hard X-ray photoemission spectroscopyAratani, Hidekazu*; Nakatani, Yasuhiro*; Fujiwara, Hidenori*; Kawada, Moeki*; Kanai, Yuina*; Yamagami, Kohei*; Fujioka, Shuhei*; Hamamoto, Satoru*; Kuga, Kentaro*; Kiss, Takayuki*; et al.
Physical Review B, 98(12), p.121113_1 - 121113_6, 2018/09
Times Cited Count：4 Percentile：21.7(Materials Science, Multidisciplinary)Ono, Ayako; Suzuki, Takayuki*; Yoshida, Hiroyuki
Proceedings of 26th International Conference on Nuclear Engineering (ICONE-26) (Internet), 6 Pages, 2018/07
The mechanism of critical heat flux (CHF) for higher system pressure remains to be clarified, even though it is important to evaluate the CHF for the light water reactor (LWR) which is operated under the high pressure condition. In this study, the process of bubble coalescence was simulated by using a computational multi-fluid dynamics (CMFD) simulation code TPFIT under various system pressure in order to investigate the behavior of bubbles as a basic study. The growth of bubbles was simulated by blowing of vapor from a tiny orifice simulating bubble bottom. One or four orifices were located on the bottom surface in this simulation study. The numerical simulations were conducted by varying the pressure and temperature.
Ono, Takayuki; Kawasaki, Satoru; Ishimori, Yuu; Ando, Masaki
JAEA-Review 2017-044, 13 Pages, 2018/03
JAEA-Review-2017-044.pdf:1.17MB
The Ningyo-toge Environmental Engineering Center of the Japan Atomic Energy Agency performs the environmental monitoring around the Ningyo-toge and the waste rock sites according to the agreements with local governments, Okayama and Tottori prefectures. Each prefectural committee on the environmental monitoring evaluates the monitoring data annually. This report summarized the results of the environmental monitoring in Tottori prefecture in the fiscal year 2016. The results show that the levels of the radiation doses and the radioactive concentrations in the environment were within natural variations, and the waste rock sites have been well maintained. The committee concluded that the environmental impacts from the sites were negligible.
Ono, Takayuki; Kawasaki, Satoru; Ishimori, Yuu; Ando, Masaki
JAEA-Review 2017-043, 39 Pages, 2018/03
JAEA-Review-2017-043.pdf:1.92MB
The Ningyo-toge Environmental Engineering Center of the Japan Atomic Energy Agency (JAEA Ningyo-toge) performs the environmental monitoring around the Ningyo-toge and the waste rock sites according to the agreements with local governments, Okayama and Tottori prefectures. Environmental monitoring of plutonium has been also performed around the Ningyo-toge regarding the practical application study on the reprocessed uranium conversion, which was carried out from 1994 to 1999 at the Ningyo-toge. Each prefectural committee on the environmental monitoring evaluates the monitoring data annually. This report summarized the results of the environmental monitoring in Okayama prefecture in the fiscal year 2016. The results show that the levels of the radiation doses and the radioactive concentrations in the environment were within natural variations, and the committee concluded that the environmental impacts from the sites were negligible. Therefore, the site of the JAEA Ningyo-toge has been well operated, and the waste rock sites have been well maintained.
