Refine your search:     
Report No.
 - 
Search Results: Records 1-20 displayed on this page of 677

Presentation/Publication Type

Initialising ...

Refine

Journal/Book Title

Initialising ...

Meeting title

Initialising ...

First Author

Initialising ...

Keyword

Initialising ...

Language

Initialising ...

Publication Year

Initialising ...

Held year of conference

Initialising ...

Save select records

Journal Articles

System of radiological protection; Towards a consistent framework on earth and in space

R$"u$hm, W.*; Ban, Nobuhiko*; Chen, J.*; Li, C.*; Dobynde, M.*; Durante, M.*; El-Jaby, S.*; Komiyama, Tatsuto*; Ozasa, Kotaro*; Sato, Tatsuhiko; et al.

Journal of Medical Physics - Zeitschrift f$"u$r medizinische Physik -, 10 Pages, 2024/00

The International Commission on Radiological Protection (ICRP) provides independent recommendations on radiological protection for the public benefit. For more than 90 years, the ICRP System of Radiological Protection has been guiding the development and implementation of national and international standards and regulations on radiological protection. In 2019, ICRP established Task Group (TG) 115 to address a broader range of topics related to dose and risk assessment for radiological protection of astronauts. This paper gives an overview of the System of Radiological Protection and a brief summary of ICRP's work on radiological protection of astronauts.

Journal Articles

Initial verification and validation of a new CASMO5 JENDL-5 nuclear data library for typical LWR applications

Watanabe, Tomoaki; Suyama, Kenya; Tada, Kenichi; Ferrer, R. M.*; Hykes, J.*; Wemple, C. A.*

Nuclear Science and Engineering, 10 Pages, 2024/00

A new nuclear data library for the advanced lattice physics code CASMO5 has been prepared based on JENDL-5. In JENDL-5, many essential nuclides for conventional LWR analysis have also been modified based on state-of-the-art evaluations. The new JENDL-5-based CASMO5 library was prepared by replacing as much of the nuclear data of the current CASMO5 ENDF/B-VII.1-based library as possible with JENDL-5. This study verified and validated the new library. Verifications were performed based on the OECD/NEA burnup credit criticality safety benchmark phase III-C, and the calculated k$$_{inf}$$ and fuel compositions of the BWR fuel assembly were compared with reported benchmark results. Comparison with the MCNP6.2 result was also performed using the same benchmark model. In addition, the TCA critical experiment and Takahama-3 post-irradiation experiment were used for validation. The results indicate that the new library performs well and is comparable to the ENDF/B-VII.1-based library in predictions of reactivity and fuel compositions for LWR systems.

Journal Articles

Void reactivity in lead and bismuth sample reactivity experiments at Kyoto University Critical Assembly

Pyeon, C. H.*; Katano, Ryota; Oizumi, Akito; Fukushima, Masahiro

Nuclear Science and Engineering, 197(11), p.2902 - 2919, 2023/11

 Times Cited Count:0 Percentile:75.85(Nuclear Science & Technology)

Sample reactivity and void reactivity experiments are carried out in the solid-moderated and solid-reflected cores at the Kyoto University Critical Assembly (KUCA) with the combined use of aluminum (Al), lead (Pb) and bismuth (Bi) samples, and Al spacers simulating the void. MCNP6.2 eigenvalue calculations together with JENDL-4.0 provide good accuracy of sample reactivity with the comparison of experimental results; also experimental void reactivity is attained by using MCNP6.2 together with JENDL-4.0 and ENDF/B-VII.1 with a marked accuracy of relative difference between experiments and calculations. Uncertainty quantification of sample reactivity and void reactivity is acquired by using the sensitivity coefficients based on MCNP6.2/ksen and covariance library data of SCALE6.2 together with ENDF/B-VII.1, arising from the impact of uncertainty induced by Al, Pb and Bi cross sections. A series of reactivity analyses with the Al spacer simulating the void demonstrates the means of analyzing the void in the solid-moderated and solid-reflected cores at KUCA

Journal Articles

Extraction of $$^{99}$$Mo hot atoms made by a neutron capture method from $$alpha$$-MoO$$_{3}$$ to water

Quach, N. M.*; Ngo, M. C.*; Yang, Y.*; Nguyen, T. B.*; Nguyen, V. T.*; Fujita, Yoshitaka; Do, T. M. D.*; Nakayama, Tadachika*; Suzuki, Tatsuya*; Suematsu, Hisayuki*

Journal of Radioanalytical and Nuclear Chemistry, 332(10), p.4057 - 4064, 2023/10

Technetium-99m ($$^{99m}$$Tc) is the most widely used medical radioisotope in the world and is produced from molybdenum-99 ($$^{99}$$Mo). Production of $$^{99}$$Mo via the neutron capture method draws attention as an alternative to fission-derived $$^{99}$$Mo due to non-proliferation issues, but the specific radioactivity of $$^{99}$$Mo is extremely low. In this work, a porous $$alpha$$-MoO$$_{3}$$ wire was prepared as an irradiation target in order to improve the specific activity by extracting $$^{99}$$Mo. Porous $$alpha$$-MoO$$_{3}$$ wire is synthesized from Mo metal wire by a two-step heating procedure. The hot atom effect of $$^{99}$$Mo was confirmed by activity and isotope measurements of the porous $$alpha$$-MoO$$_{3}$$ wire after neutron irradiation and the water used for extraction. In term of the extraction effectiveness, the effectiveness of $$^{99}$$Mo extraction in the porous $$alpha$$-MoO$$_{3}$$ wire was comparable to that of commercial $$alpha$$-MoO$$_{3}$$ powder.

Journal Articles

$$beta$$-MoO$$_{3}$$ whiskers in $$^{99}$$Mo/$$^{rm 99m}$$Tc radioisotope production and $$^{99}$$Mo/$$^{rm 99m}$$Tc extraction using hot atoms

Ngo, M. C.*; Fujita, Yoshitaka; Suzuki, Tatsuya*; Do, T. M. D.*; Seki, Misaki; Nakayama, Tadachika*; Niihara, Koichi*; Suematsu, Hisayuki*

Inorganic Chemistry, 62(32), p.13140 - 13147, 2023/08

 Times Cited Count:0 Percentile:0.01

Technetium-99m ($$^{rm 99m}$$Tc) is one of the most important radioisotopes for diagnostic radio-imaging applications. $$^{rm 99m}$$Tc is a daughter product of the $$^{99}$$Mo isotope. There are two methods used to produce $$^{99}$$Mo/$$^{rm 99m}$$Tc: the nuclear fission (n,f) and the neutron capture (n,$$gamma$$) methods. Between them, the (n,f) method is the main route, used for approximately 90% of the world's production. However, the (n,f) method faces numerous problems, including the use of highly enriched uranium, the release of highly radioactive waste, and nonproliferation problems. Therefore, the (n,$$gamma$$) method is being developed as a future replacement for the (n,f) method. In this work, $$beta$$-MoO$$_{3}$$ whiskers prepared by the thermal evaporation method and $$alpha$$-MoO$$_{3}$$ particles were irradiated in a nuclear reactor to produce $$^{99}$$Mo/$$^{rm 99m}$$Tc via neutron capture. The irradiated targets were dispersed into water to extract the $$^{99}$$Mo/$$^{rm 99m}$$Tc. As a result, $$beta$$-MoO$$_{3}$$ whisker yielded higher $$^{99}$$Mo extraction rate than that from $$alpha$$-MoO$$_{3}$$. In addition, by comparing the dissolved $$^{98}$$Mo concentrations in water, we clarified a prominent hot-atom of $$beta$$-MoO$$_{3}$$ whiskers. This research is the first demonstration of $$beta$$-MoO$$_{3}$$ being used as an irradiation target in the neutron capture method. On the basis of the results, $$beta$$-MoO$$_{3}$$ is considered a promising irradiation target for producing $$^{99}$$Mo/$$^{rm 99m}$$Tc by neutron capture and using water for the radioisotope extraction process in the future.

Journal Articles

First observation of $$^{28}$$O

Kondo, Yosuke*; Achouri, N. L.*; Al Falou, H.*; Atar, L.*; Aumann, T.*; Baba, Hidetada*; Boretzky, K.*; Caesar, C.*; Calvet, D.*; Chae, H.*; et al.

Nature, 620(7976), p.965 - 970, 2023/08

no abstracts in English

Journal Articles

Intruder configurations in $$^{29}$$Ne at the transition into the island of inversion; Detailed structure study of $$^{28}$$Ne

Wang, H.*; Yasuda, Masahiro*; Kondo, Yosuke*; Nakamura, Takashi*; Tostevin, J. A.*; Ogata, Kazuyuki*; Otsuka, Takaharu*; Poves, A.*; Shimizu, Noritaka*; Yoshida, Kazuki; et al.

Physics Letters B, 843, p.138038_1 - 138038_9, 2023/08

Detailed $$gamma$$-ray spectroscopy of the exotic neon isotope $$^{28}$$Ne has been performed using the one-neutron removal reaction from $$^{29}$$Ne. Based on an analysis of parallel momentum distributions, a level scheme with spin-parity assignments has been constructed for $$^{28}$$Ne and the negative-parity states are identified for the first time. The measured partial cross sections and momentum distributions reveal a significant intruder p-wave strength providing evidence of the breakdown of the N = 20 and N = 28 shell gaps. Only a weak, possible f-wave strength was observed to bound final states. Large-scale shell-model calculations with different effective interactions do not reproduce the large p-wave and small f-wave strength observed experimentally, indicating an ongoing challenge for a complete theoretical description of the transition into the island of inversion along the Ne isotopic chain.

Journal Articles

OECD/NEA ARC-F Project; Summary of fission product transport

Lind, T.*; Kalilainen, J.*; Marchetto, C.*; Beck, S.*; Nakamura, Koichi*; Kino, Chiaki*; Maruyama, Yu; Kido, Kentaro; Kim, S. I.*; Lee, Y.*; et al.

Proceedings of 20th International Topical Meeting on Nuclear Reactor Thermal Hydraulics (NURETH-20) (Internet), p.4796 - 4809, 2023/08

Journal Articles

Pressure-modulated magnetism and negative thermal expansion in the Ho$$_2$$Fe$$_{17}$$ intermetallic compound

Cao, Y.*; Zhou, H.*; Khmelevskyi, S.*; Lin, K.*; Avdeev, M.*; Wang, C.-W.*; Wang, B.*; Hu, F.*; Kato, Kenichi*; Hattori, Takanori; et al.

Chemistry of Materials, 35(8), p.3249 - 3255, 2023/04

 Times Cited Count:0 Percentile:0(Chemistry, Physical)

Hydrostatic and chemical pressure are efficient stimuli to alter the crystal structure and are commonly used for tuning electronic and magnetic properties in materials science. However, chemical pressure is difficult to quantify and a clear correspondence between these two types of pressure is still lacking. Here, we study intermetallic candidates for a permanent magnet with a negative thermal expansion (NTE). Based on in situ synchrotron X-ray diffraction, negative chemical pressure is revealed in Ho$$_2$$Fe$$_{17}$$ on Al doping and quantitatively evaluated by using temperature and pressure dependence of unit cell volume. A combination of magnetization and neutron diffraction measurements also allowed one to compare the effect of chemical pressure on magnetic ordering with that of hydrostatic pressure. Intriguingly, pressure can be used to control suppression and enhancement of NTE. Electronic structure calculations indicate that pressure affected the top of the majority band with respect to the Fermi level, which has implications for the magnetic stability, which in turn plays a critical role in modulating magnetism and NTE. This work presents a good example of understanding the effect of pressure and utilizing it to control properties of functional materials.

Journal Articles

Elastic properties of nuclear pasta in a fully three-dimensional geometry

Xia, C.-J.*; Maruyama, Toshiki; Yasutake, Nobutoshi*; Tatsumi, Toshitaka*; Zhang, Y.-X.*

Physics Letters B, 839, p.137769_1 - 137769_5, 2023/04

 Times Cited Count:1 Percentile:70.47(Astronomy & Astrophysics)

Journal Articles

Hybridized propagation of spin waves and surface acoustic waves in a multiferroic-ferromagnetic heterostructure

Chen, J.*; Yamamoto, Kei; Zhang, J.*; Ma, J.*; Wang, H.*; Sun, Y.*; Chen, M.*; Ma, J.*; Liu, S.*; Gao, P.*; et al.

Physical Review Applied (Internet), 19(2), p.024046_1 - 024046_9, 2023/02

 Times Cited Count:1 Percentile:92.2(Physics, Applied)

Journal Articles

Comparison of dose and risk estimates between ISS Partner Agencies for a 30-day Lunar Mission

Shavers, M. R.*; Semones, E. J.*; Shurshakov, V.*; Dobynde, M.*; Sato, Tatsuhiko; Komiyama, Tatsuto*; Tomi, L.*; Chen, J.*; El-Jaby, S.*; Straube, U.*; et al.

Journal of Medical Physics - Zeitschrift f$"u$r medizinische Physik -, 13 Pages, 2023/00

The Partner Agencies of the International Space Station (ISS) present an intracomparison of the ionizing radiation absorbed dose and risk quantities used to characterize example mission lunar space. The results and the work itself provide insights to the level of agreement with which space agencies can perform organ dosimetry and calculate effective dose. This work was performed in collaboration with the advisory and guidance efforts of the International Commission on Radiological Protection (ICRP) Task Group 115 and will be presented in an ICRP Report

Journal Articles

Impact of uncertainty reduction on lead-bismuth coolant in accelerator-driven system using sample reactivity experiments

Katano, Ryota; Oizumi, Akito; Fukushima, Masahiro; Pyeon, C. H.*; Yamamoto, Akio*; Endo, Tomohiro*

Nuclear Science and Engineering, 20 Pages, 2023/00

In this study, we have demonstrated that data assimilation using lead and bismuth sample reactivities measured in the Kyoto University Critical Assembly A-core can successfully reduce the uncertainty of the coolant void reactivity in accelerator-driven systems derived from inelastic-scattering cross-sections of lead and bismuth. We re-evaluated and highlighted the experimental uncertainties and correlations of the sample reactivities for the data assimilation formula. We used the MCNP6.2 code to evaluate the sample reactivities and their uncertainties, and performed data assimilation using the reactor analysis code system MARBLE. The high-sensitivity coefficients of the sample reactivities to lead and bismuth allowed us to reduce the cross-section-induced uncertainty of the void reactivity of the accelerator-driven system from 6.3% to 4.8%, achieving a provisional target accuracy of 5% in this study. Furthermore, we demonstrated that the uncertainties arising from other dominant factors, such as minor actinides and steel, can be effectively reduced by using integral experimental data sets for the unified cross-section dataset ADJ2017.

Journal Articles

Core and safety design for France-Japan common concept on sodium-cooled fast reactor

Takano, Kazuya; Oki, Shigeo; Ozawa, Takayuki; Yamano, Hidemasa; Kubo, Shigenobu; Ogura, Masashi*; Yamada, Yumi*; Koyama, Kazuya*; Kurita, Koichi*; Costes, L.*; et al.

EPJ Nuclear Sciences & Technologies (Internet), 8, p.35_1 - 35_9, 2022/12

The France and Japan teams have carried out collaborative works to have common technical views regarding a sodium-cooled fast reactor concept. Japan has studied the feasibility of an enhanced high burnup low-void effect (CFV) core and fuel using oxide dispersion-strengthened steel cladding in ASTRID 600. Regarding passive shutdown capabilities, Japan team has performed a preliminary numerical analysis for ASTRID 600 using a complementary safety device, called a self-actuated shutdown system (SASS), one of the safety approaches of Japan. The mitigation measures of ASTRID 600 against a severe accident, such as a core catcher, molten corium discharge assembly, and the sodium void reactivity features of the CFV core, are promising to achieve in-vessel retention for both countries. The common design concept based on ASTRID 600 is feasible to demonstrate the SFR core and safety technologies for both countries.

Journal Articles

Third international challenge to model the medium- to long-range transport of radioxenon to four Comprehensive Nuclear-Test-Ban Treaty monitoring stations

Maurer, C.*; Galmarini, S.*; Solazzo, E.*; Ku$'s$mierczyk-Michulec, J.*; Bar$'e$, J.*; Kalinowski, M.*; Schoeppner, M.*; Bourgouin, P.*; Crawford, A.*; Stein, A.*; et al.

Journal of Environmental Radioactivity, 255, p.106968_1 - 106968_27, 2022/12

 Times Cited Count:0 Percentile:16.29(Environmental Sciences)

After performing multi-model exercises in 2015 and 2016, a comprehensive Xe-133 atmospheric transport modeling challenge was organized in 2019. For evaluation measured samples for the same time frame were gathered from four International Monitoring System stations located in Europe and North America with overall considerable influence of IRE and/or CNL emissions. As a lesion learnt from the 2nd ATM-Challenge participants were prompted to work with controlled and harmonized model set ups to make runs more comparable, but also to increase diversity. Effects of transport errors, not properly characterized remaining emitters and long IMS sampling times (12 to 24 hours) undoubtedly interfere with the effect of high-quality IRE and CNL stack data. An ensemble based on a few arbitrary submissions is good enough to forecast the Xe-133 background at the stations investigated. The effective ensemble size is below five.

Journal Articles

Rediscovery of Hall-Petch strengthening in bulk ultrafine grained pure Mg at cryogenic temperature; A Combined ${it in situ}$ neutron diffraction and electron microscopy study

Zheng, R.*; Gong, W.; Du, J.-P.*; Gao, S.*; Liu, M.*; Li, G.*; Kawasaki, Takuro; Harjo, S.; Ma, C.*; Ogata, Shigenobu*; et al.

Acta Materialia, 238, p.118243_1 - 118243_15, 2022/10

 Times Cited Count:9 Percentile:93.63(Materials Science, Multidisciplinary)

Journal Articles

Micro- to nano-scale areal heterogeneity in pore structure and mineral compositions of a sub-decimeter-sized Eagle Ford Shale

Wang, Q.*; Hu, Q.*; Zhao, C.*; Yang, X.*; Zhang, T.*; Ilavsky, J.*; Kuzmenko, I.*; Ma, B.*; Tachi, Yukio

International Journal of Coal Geology, 261, p.104093_1 - 104093_15, 2022/09

 Times Cited Count:3 Percentile:72.03(Energy & Fuels)

Journal Articles

Nuclear pasta structures at high temperatures

Xia, C.-J.*; Maruyama, Toshiki; Yasutake, Nobutoshi*; Tatsumi, Toshitaka*

Physical Review D, 106(6), p.063020_1 - 063020_14, 2022/09

 Times Cited Count:3 Percentile:52.13(Astronomy & Astrophysics)

Journal Articles

Two-step Mott transition in Ni(S,Se)$$_2$$; $$mu$$SR studies and charge-spin percolation model

Sheng, Q.*; Kaneko, Tatsuya*; Yamakawa, Kohtaro*; Guguchia, Z.*; Gong, Z.*; Zhao, G.*; Dai, G.*; Jin, C.*; Guo, S.*; Fu, L.*; et al.

Physical Review Research (Internet), 4(3), p.033172_1 - 033172_14, 2022/09

Journal Articles

Performance evaluation of commercial scintillation cocktails for low-level tritium counting by high-capacity liquid scintillation counter

Kuwata, Haruka*; Tazoe, Hirofumi*; Kranrod, C.*; Fujiwara, Kenso; Terashima, Motoki; Matsueda, Makoto; Hirao, Shigekazu*; Akata, Naofumi*

Radiation Protection Dosimetry, 198(13-15), p.1014 - 1018, 2022/09

 Times Cited Count:0 Percentile:0.01(Environmental Sciences)

677 (Records 1-20 displayed on this page)