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Journal Articles

Uncertainty quantification for severe-accident reactor modelling; Results and conclusions of the MUSA reactor applications work package

Brumm, S.*; Gabrielli, F.*; Sanchez Espinoza, V.*; Stakhanova, A.*; Groudev, P.*; Petrova, P.*; Vryashkova, P.*; Ou, P.*; Zhang, W.*; Malkhasyan, A.*; et al.

Annals of Nuclear Energy, 211, p.110962_1 - 110962_16, 2025/02

 Times Cited Count:1 Percentile:75.38(Nuclear Science & Technology)

Journal Articles

In-situ measurement of radiation driven back-conversion from para to ortho liquid hydrogen state in cold moderators at J-PARC

Teshigawara, Makoto; Lee, Y.*; Tatsumoto, Hideki*; Hartl, M.*; Aso, Tomokazu; Iverson, E. B.*; Ariyoshi, Gen; Ikeda, Yujiro*; Hasegawa, Takumi*

Nuclear Instruments and Methods in Physics Research B, 557, p.165534_1 - 165534_10, 2024/12

 Times Cited Count:0 Percentile:0.00(Instruments & Instrumentation)

At Japanese Spallation Neutron Source in J-PARC, the para-hydrogen fraction was measured by using Raman spectroscopy in-situ for an integrated beam power of 9.4 MW$$cdot$$h at 1 MW operation, to evaluate the functionality of the ferric oxyhydroxide catalyst. This result showed that full functionality of the catalyst was retained up to the 1 MW operation. We attempted to study the effect of neutron scattering driven para to ortho-hydrogen back-conversion rate in the absence of the catalyst effect with a bypass line without catalyst. The measured increase of ortho-hydrogen fraction was 0.44% for an integrated beam power of 2.4 MW$$cdot$$h at 500 kW operation, however, which was considered to be due to not only to neutron collisions in cold moderators but also to the high ortho-hydrogen fraction of initially static liquid hydrogen in the bypass line and passive exudation of quasi-static hydrogen in the catalyst vessel to the main loop.

Journal Articles

Status of the uncertainty quantification for severe accident sequences of different NPP-designs in the frame of the H-2020 project MUSA

Brumm, S.*; Gabrielli, F.*; Sanchez-Espinoza, V.*; Groudev, P.*; Ou, P.*; Zhang, W.*; Malkhasyan, A.*; Bocanegra, R.*; Herranz, L. E.*; Berda$"i$, M.*; et al.

Proceedings of 10th European Review Meeting on Severe Accident Research (ERMSAR 2022) (Internet), 13 Pages, 2022/05

Journal Articles

Programmable synthesis of silver wheels

Kwon, H.*; Pietrasiak, E.*; Ohara, Takashi; Nakao, Akiko*; Chae, B.*; Hwang, C.-C.*; Jung, D.*; Hwang, I.-C.*; Ko, Y. H.*; Kim, K.*; et al.

Inorganic Chemistry, 60(9), p.6403 - 6409, 2021/05

 Times Cited Count:0 Percentile:0.00(Chemistry, Inorganic & Nuclear)

Journal Articles

Laboratory examination of greenhouse gaseous and microbial dynamics during thawing of frozen soil core collected from a black spruce forest in Interior Alaska

Nagano, Hirohiko; Kim, Y.*; Lee, B.-Y.*; Shigeta, Haruka*; Inubushi, Kazuyuki*

Soil Science and Plant Nutrition, 64(6), p.793 - 802, 2018/12

 Times Cited Count:5 Percentile:23.80(Plant Sciences)

In this study, we conducted an incubation experiment on a frozen soil core collected from a black spruce forest in Interior Alaska, in order to investigate potential changes in greenhouse gaseous (GHG) and microbial dynamics during thawing of frozen soil. The soil thawing is an important environmental process determining the annual GHG balance in the northern high-latitude ecosystem. A core spanning the ground surface to upper permafrost with a depth of 90 cm was vertically grouped into three layers (top, middle, and bottom layers). Then, 12 soil samples from 3 layers (i.e., 4 soil samples per layer) were incubated for 3 weeks, and net carbon dioxide (Co$$_{2}$$) and methane (CH$$_{4}$$) release/uptake rates were estimated. During the incubation, temperature was changed weekly from 0 to 5, then 10$$^{circ}$$C. The net amounts of CO$$_{2}$$ released by six of the eight soil samples from the top and middle layers were 1.5 to 19.2-fold greater at 5$$^{circ}$$C than at 0$$^{circ}$$C, while the release at 10$$^{circ}$$C was reduced in the cases of three of these six soil samples. Net CH$$_{4}$$ release was the greatest in bottom-layer soil samples incubated at 0$$^{circ}$$C. Then, low but apparent CH$$_{4}$$ release was observed in top and middle-layer soil samples incubated at 0$$^{circ}$$C. At 5 and 10$$^{circ}$$C, net CH$$_{4}$$ release from bottom-layer soil samples was decreased. Then, net CH$$_{4}$$ uptake was observed in the top and the middle-layer soil samples. Both net uptake and release of CH$$_{4}$$ were reduced upon the addition of a chemical inhibitor (i.e., 2-bromoethane sulfonate) of anaerobic methanotrophic and methanogenic activity. The bacterial and archaeal community structures based on 16S rRNA amplicon analysis were changed along the depth, while they were less changed during thawing. Thus, it was found that soil GHG dynamics responded sensitively and variously to thawing, while there was less change in 16S rRNA-based microbial community structures during the thawing prog

Journal Articles

Investigation of the electronic structure and lattice dynamics of the thermoelectric material Na-doped SnSe

Wu, P.*; Zhang, B.*; Peng, K. L.*; Hagiwara, Masayuki*; Ishikawa, Yoshihisa*; Kofu, Maiko; Lee, S. H.*; Kumigashira, Hiroshi*; Hu, C. S.*; Qi, Z. M.*; et al.

Physical Review B, 98(9), p.094305_1 - 094305_7, 2018/09

 Times Cited Count:13 Percentile:50.83(Materials Science, Multidisciplinary)

Using angle-resolved photoemission spectroscopy and inelastic neutron scattering, we have studied how electronic structures and lattice dynamics evolve with temperature in Na-doped SnSe.

Journal Articles

Multi-threading performance of Geant4, MCNP6, and PHITS Monte Carlo codes for tetrahedral-mesh geometry

Han, M. C.*; Yeom, Y. S.*; Lee, H. S.*; Shin, B.*; Kim, C. H.*; Furuta, Takuya

Physics in Medicine & Biology, 63(9), p.09NT02_1 - 09NT02_9, 2018/05

 Times Cited Count:9 Percentile:43.82(Engineering, Biomedical)

The multi-threading computation performances of the Geant4, MCNP6, and PHITS codes were evaluated using three tetrahedral-mesh phantoms with different complexity. Photon and neutron transport simulations were conducted and the initialization time, calculation time, and memory usage were measured as a function of the number of threads N used in the simulation. The initialization time significantly increases with the complexity of the phantom, but not much with the number of the threads. For the calculation time, Geant4 showed good parallelization efficiency with multi-thread computation (30 times speed-up factor for N = 40) adopting the private tallies while saturation of the speed-up factor were observed in MCNP6 and PHITS (10 and a few times for N = 40) due to the time delay for the sharing tallies. On the other hand, Geant4 requires larger memory specification and the memory usage rapidly increases with the number of threads compared to MCNP6 or PHITS. It is notable that when compared to the other codes, the memory usage of PHITS is much smaller, regardless of both the complexity of the phantom and the number of the threads.

Journal Articles

Information sharing framework among experts for facilitating development of fast reactors and fuel cycles

Kawakubo, Yoko; Hoffheins, B.; Inoue, Naoko; Mongiello, R.*; Baldwin, G.*; Lee, N. Y.*

Proceedings of International Conference on Fast Reactors and Related Fuel Cycles; Safe Technologies and Sustainable Scenarios (FR-13) (USB Flash Drive), 8 Pages, 2013/03

Transparency in the peaceful use of nuclear energy is important as a measure to complement and reinforce International Atomic Energy Agency (IAEA) safeguards and promote international/ regional confidence building. Moreover, information sharing, a key component of confidence building, is essential for promoting the development of fast reactors and associated fuel cycles by enhancing transparency and encouraging understanding among non-proliferation experts. Currently, Japan Atomic Energy Agency (JAEA) is carrying out a joint project to design and establish an Information-Sharing Framework (ISF) for supporting and promoting nuclear transparency in the Asia Pacific region, in cooperation with Sandia National Laboratories (SNL), the Korean Institute for Nonproliferation and Control (KINAC), and Korea Atomic Energy Research Institute (KAERI). At present, requirements for planning and implementing ISF are under discussion to address inherent challenges that are recognized among project partners. This paper describes the current status of the development of requirements for ISF. The effort of the development is still underway, however; the requirements will be determined and demonstrated in the near future by project partners.

Journal Articles

Sediment trap record of alkenones from the East Sea (Japan Sea)

Lee, K. E.*; Khim, B.-K.*; Otosaka, Shigeyoshi; Noriki, Shinichiro*

Organic Geochemistry, 42(3), p.255 - 261, 2011/03

 Times Cited Count:16 Percentile:42.32(Geochemistry & Geophysics)

Long chain (C$$_{37}$$) alkenones in sinking particles obtained from the northeastern and the southern regions of the Japan Sea were examined to investigate the characteristics of production, export, and degradation of organic materials in the water column. A comparison of alkenone temperatures with satellite sea surface temperatures (SST) revealed that the alkenone temperatures were higher (6-13 $$^{circ}$$C) than SST during winter time, and lower (2-5 $$^{circ}$$C) during summer time. It indicated that there was a time lag between the SST and the trap records (about 3 months in winter and 1 month in summer). But, the annual average alkenone temperatures are close to annual average SST in the Yamato Basin. The reasons for this time lag can be (1) subsurface production of alkenones in summer and (2) slow settling velocity and long residence time of alkenones in the upper water column especially during winter time.

Journal Articles

Final results of an analytical round robin exercise to support constraint effects

Scibetta, M.*; Altstadt, E.*; Callejas, R.*; Lee, B.*; Miura, Naoki*; Onizawa, Kunio; Paffumi, E.*; Serrano, M.*; Tatar, L.*; Yin, S.*

Proceedings of 2009 ASME Pressure Vessels and Piping Division Conference (PVP 2009) (CD-ROM), 11 Pages, 2009/07

IAEA has developed a coordinated research project (CRP) to evaluate various issues associated with the fracture toughness Master Curve for application to light-water RPVs. Topic Area 1 of the CRP is focused on the issue of test specimen geometry effects, with emphasis on determination of reference temperature T0 with the pre-cracked Charpy specimen and the bias effect. Within the analytical part, elastic plastic finite element methods are used in order to access local stress and strain information. This analytical round robin exercise has been performed by ten laboratories from nine different countries focusing on the modeling of realistic three dimensional geometries containing shallow and deep crack. Independently of the used code and of relatively small user effect differences, it is found that shallow crack specimens are more sensitive to loss of constraint than deep crack specimens for a given specimen size. The difference in terms of reference temperature between the two geometries is evaluated to be about 40$$^{circ}$$C.

Journal Articles

IAEA coordinated research project on master curve approach to monitor fracture toughness of RPV steels; Final results of the experimental exercise to support constraint effects

Nanstad, R.*; Brumovsky, M.*; Callejas, R.*; Gillemot, F.*; Korshunov, M.*; Lee, B.*; Lucon, E.*; Scibetta, M.*; Minnebo, P.*; Nilsson, K.-F.*; et al.

Proceedings of 2009 ASME Pressure Vessels and Piping Division Conference (PVP 2009) (CD-ROM), 13 Pages, 2009/07

IAEA has developed a coordinated research project (CRP) to evaluate various issues associated with the fracture toughness Master Curve for application to light-water RPVs. Topic Area 1 of the CRP is focused on the issue of test specimen geometry effects, with emphasis on determination of reference temperature T$$_{0}$$ with the pre-cracked Charpy (PCC) specimen and the bias effect on T$$_{0}$$. Participating organizations for the experimental part of the CRP performed fracture toughness testing of various steels with various types of specimens under various conditions. Results from fracture toughness tests are compared with regard to effects of specimen size and type on the T$$_{0}$$. It is apparent from the results that the bias observed between the PCC specimen and larger specimens for Plate JRQ is not nearly as large as that obtained for other steels (-11$$^{circ}$$C to -45$$^{circ}$$C). This observation is consistent with observations in the literature that show significant variations in the bias that are dependent on the specific materials being tested.

Journal Articles

An Inter-comparison of the neutron calibration fields by D$$_{2}$$O moderated $$^{252}$$Cf source at JAEA and KAERI

Kowatari, Munehiko; Fujii, Katsutoshi; Tsutsumi, Masahiro; Kim, B.-H.*; Lee, K.-C.*; Yoshizawa, Michio; Yamaguchi, Yasuhiro

Journal of Nuclear Science and Technology, 45(Suppl.5), p.217 - 220, 2008/06

 Times Cited Count:1 Percentile:9.79(Nuclear Science & Technology)

no abstracts in English

Oral presentation

Long-pulse production of positive ion beams from JT-60U for JT-60 Super Advanced

Hanada, Masaya; Kojima, Atsushi; Akino, Noboru; Komata, Masao; Mogaki, Kazuhiko; Oh, B. H.*; Jeong, S. H.*; Chang, D. H.*; Lee, K. W.*; Bae, Y. S.*

no journal, , 

no abstracts in English

Oral presentation

Observation of the signal increase for electrochemical devices placed near PWR and intense tritium source

Suda, Shoya*; Ishibashi, Kenji*; Lee, E.*; Shigyo, Nobuhiro*; Ikeda, Nobuo*; Sun, G. M.*; Han, B.-Y.*; Takada, Hiroshi; Harada, Masahide

no journal, , 

Our group has experience to carry out the experiment with small electrochemical devices at heavy-water-moderated Advanced Thermal Reactor (ATR, FUGEN), and observed a clear signal increase near the reactor core. The present study is aiming at demonstrating the response of the electrochemical device to tritium amount. The experiments were performed at (1) Pressurized right Water Reactor (PWR, tritium amount of 30 g and a great quantity of beta emitters) at a distance of 26 m from the core, and (2) Tritium Process Laboratory of Japan Atomic Energy Agency (TPL, tritium amount ~10 g) at a position of 8.6 m from the source. Signal increase was observed in both measurements. Analysis made clear that the detector signal is ascribed to the amount of low-energy beta emitters of plutonium 241 and tritium in the PWR experiment while it is attributed to the quantity of tritium in the TPL measurement.

14 (Records 1-14 displayed on this page)
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