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JAEA Reports

Detailed computational models for nuclear criticality analyses on the first startup cores of NSRR: A TRIGA annular core pulse reactor

Yanagisawa, Hiroshi; Motome, Yuiko

JAEA-Research 2025-001, 99 Pages, 2025/06

JAEA-Research-2025-001.pdf:1.98MB

The detailed computational models for nuclear criticality analyses on the first startup cores of NSRR (Nuclear Safety Research Reactor), which is categorized as a TRIGA-ACPR (Annular Core Pulse Reactor), were created for the purposes of deeper understandings of safety inspection data on the neutron absorber rod worths of reactivity and improvement of determination technique of the reactivity worths. The uncertainties in effective neutron multiplication factor (k$$_{rm eff}$$) propagated from errors in the geometry, material, and operation data for the present models were evaluated in detail by using the MVP version 3 code with the latest Japanese nuclear data library, JENDL-5, and the previous versions of JENDL libraries. As a result, the overall uncertainties in k$$_{rm eff}$$ for the present models were evaluated to be in the range of 0.0027 to 0.0029 $$Delta$$k$$_{rm eff}$$. It is expected that the present models will be utilized as the benchmark on k$$_{rm eff}$$ for TRIGA-ACPR. Moreover, it is confirmed that the overall uncertainties were sufficiently smaller than the values of absorber rod worths determined in NSRR. Thus, it is also considered that the present models are applicable to further analyses on the absorber rod worths in NSRR.

Journal Articles

Investigation on multi-dimensional short-term behaviour through benchmark analysis of a large-volume sodium combustion experiment

Sonehara, Masateru; Okano, Yasushi; Uchibori, Akihiro; Oki, Hiroshi*

Journal of Nuclear Science and Technology, 62(5), p.403 - 414, 2025/05

 Times Cited Count:0 Percentile:0.00(Nuclear Science & Technology)

For sodium-cooled fast reactors, understanding sodium combustion behaviour is crucial for managing sodium leakage accidents. In this study, we perform benchmark analyses of the Sandia National Laboratories (SNL) T3 experiment using the multi-dimensional thermal hydraulic code AQUA-SF. Conducted in an enclosed space with a large vessel volume of 100 m$$^3$$ and a sodium mass flow rate of 1 kg/s, the experiment highlighted the multi-dimensional effects of local temperature increase shortly after sodium injection. This study aims to extend the capabilities of AQUA-SF by focusing on the simulation of these multi-dimensional temperature variations, in particular the formation of high temperature regions at the bottom of the vessel. The proposed models include the temporary stopping of sodium droplet ignition and spray combustion of sodium splash on the floor. Furthermore, it has been shown that additional heat source near the floor is essential to enhance the reproduction of the high temperature region at the bottom. Therefore, case studies including sensitivity analyses of spray cone angle and prolonged combustion of droplets on the floor are conducted. This comprehensive approach provides valuable insights into the dynamics of sodium combustion and safety measures in sodium-cooled fast reactors.

Journal Articles

Comparison of analysis results based on flight methods using a CZT detector system on an unmanned aerial vehicle near the Fukushima nuclear power plant

Joung, S.*; Ji, Y.-Y.*; Choi, Y.*; Lee, E.*; Ji, W.*; Sasaki, Miyuki; Ochi, Kotaro; Sanada, Yukihisa

Journal of Instrumentation (Internet), 20(4), p.P04027_1 - P04027_10, 2025/04

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

Journal Articles

JENDL-5 benchmarking for advanced test reactor for preparing burnup analysis using isotopic data from HTGR type fuel irradiation tests

Okita, Shoichiro; Aoki, Takeshi; Fukaya, Yuji; Tachibana, Yukio

Proceedings of 31st International Conference on Nuclear Engineering (ICONE31) (Internet), 5 Pages, 2024/11

Journal Articles

The Development of Petri Net-based continuous Markov Chain Monte Carlo methodology applying to dynamic probability risk assessment for multi-state resilience systems with repairable multi-component interdependency under longtermly thereat

Li, C.-Y.; Watanabe, Akira*; Uchibori, Akihiro; Okano, Yasushi

Journal of Nuclear Science and Technology, 61(7), p.935 - 957, 2024/07

 Times Cited Count:2 Percentile:43.92(Nuclear Science & Technology)

Journal Articles

A Preliminary uncertainty analysis of PWR depletion numerical test problem on OECD/NEA/NSC LWR-UAM benchmark phase II based on JENDL-5

Fujita, Tatsuya

Proceedings of Best Estimate Plus Uncertainty International Conference (BEPU 2024) (Internet), 14 Pages, 2024/05

The uncertainty analysis of PWR depletion test problem on the OECD/NEA/NSC LWR-UAM benchmark Phase II based on JENDL-5 was performed as a preliminary investigation. The random sampling was used to quantify the uncertainty of k-infinity and nuclide inventories, the cross section (XS), the fission product yield (FPY), the decay constant, and the decay branch ratio were randomly perturbed, and several times of SERPENT 2.2.1 calculations were performed. XSs in the ACE file were perturbed by the ACE file perturbation tool using FRENDY with the 56-group covariance matrix generated by NJOY2016.72. The perturbation quantity of independent FPY was evaluated using the FPY covariance matrix prepared in JENDL-5, and the perturbed cumulative FPY was reconstructed based on the relationship between the independent and cumulative FPYs. The decay constant was independently perturbed for each nuclide. To perturb the decay branch ratios, the covariance matrix was generated by applying the generalized least square method and randomly perturbed based on this covariance matrix in the same manner as the independent FPY. In general, the influence due to decay data was an order of magnitude smaller than the influences due to XS and FPY uncertainties. For the uncertainty of k-infinity and transuranic nuclide inventories, the influence due to XS uncertainty was dominant, and that due to FPY and decay data uncertainties was one or a few orders of magnitude smaller. On the other hand, for the uncertainty of FP nuclide inventories, the influence due to FPY uncertainty was almost the same or larger than that due to XS uncertainty. It was also confirmed that the influence due to either XS or FPY uncertainty became different for each FP nuclide. In future studies, the influence due to XS uncertainty on FP nuclides will be discussed because it was not prepared in JENDL-5 and not considered in the present paper.

Journal Articles

Benchmark analyses on control rod worths of TRIGA reactor modeled in the ICSBEP handbook using continuous-energy Monte Carlo code MVP version 3

Yanagisawa, Hiroshi; Umeda, Miki; Motome, Yuiko; Murao, Hiroyuki

Proceedings of 12th International Conference on Nuclear Criticality Safety (ICNC2023) (Internet), 10 Pages, 2023/10

The benchmark analyses on the TRIGA reactor of the IEU-COMP-THERM-013 (ICT-013) in the ICSBEP handbook using the MVP version 3 code were carried out with the Japanese, US and European nuclear data libraries, including JENDL-5. The analyses on effective neutron multiplication factors (k$$_{eff}$$'s) were also performed for another TRIGA reactor defined in the ICT-003 as well as the ICT-013. As a result, it is confirmed that the calculated k$$_{eff}$$'s vary in the range of 0.8% with the libraries. The results also suggest that there might be unknown bias in the ICT-013 for the calculated k$$_{eff}$$'s. For the analyses on the control rod worths of the ICT-013, it is confirmed that differences in the worths among the libraries become smaller than those in k$$_{eff}$$'s. Most of the errors involved in k$$_{eff}$$'s are considered to be cancelled in the calculation of the worths since the worths are obtained by subtraction of the reciprocals of two sorts of k$$_{eff}$$'s. The differences in the worths by between the benchmark and alternative methods defined in the ICT-013 were tried to be examined from the aspect of the differences in horizontal flux distributions by between those methods. It is confirmed that the differences in the worths for two shim control rods, which are fully withdrawn at a delayed critical state, are well understood by that attempt, but on the other hand the differences are not sufficiently explained for a regulating control rod, which is partially inserted to attain delayed criticality.

Journal Articles

Journal Articles

Large-eddy simulation on two-liquid mixing in the horizontal leg and downcomer (the TAMU-CFD Benchmark), with respect to fluctuation behavior of liquid concentration

Abe, Satoshi; Okagaki, Yuria

Nuclear Engineering and Design, 404, p.112165_1 - 112165_14, 2023/04

 Times Cited Count:3 Percentile:43.92(Nuclear Science & Technology)

Journal Articles

Development of adjusted nuclear data library for fast reactor application

Yokoyama, Kenji

EPJ Web of Conferences, 281, p.00004_1 - 00004_10, 2023/03

In Japan, development of adjusted nuclear data library for fast rector application based on the cross-section adjustment method has been conducted since the early 1990s. The adjusted library is called the unified cross-section set. The first version was developed in 1991 and is called ADJ91. Recently, the integral experimental data were further expanded to improve the design prediction accuracy of the core loaded with minor actinoids and/or degraded Pu. Using the additional integral experimental data, development of ADJ2017 was started in 2017. In 2022, the latest unified cross-section set AJD2017R was developed based on JENDL-4.0 by using 619 integral experimental data. An overview of the latest version with a review of previous ones will be shown. On the other hand, JENDL-5 was released in 2021. In the development of JENDL-5, some of the integral experimental data used in ADJ2017R were explicitly utilized in the nuclear data evaluation. However, this is not reflected in the covariance data. This situation needs to be considered when developing a unified cross-section set based on JENDL-5. Preliminary adjustment calculation based on JENDL-5 is performed using C/E (calculation/experiment) values simply evaluated by a sensitivity analysis. The preliminary results will be also discussed.

JAEA Reports

Nuclear criticality benchmark analyses on TRIGA-type reactor systems by using continuous-energy Monte Carlo code MVP with JENDL-5

Yanagisawa, Hiroshi; Umeda, Miki; Motome, Yuiko; Murao, Hiroyuki

JAEA-Technology 2022-030, 80 Pages, 2023/02

JAEA-Technology-2022-030.pdf:2.57MB
JAEA-Technology-2022-030(errata).pdf:0.11MB

Nuclear criticality benchmark analyses were carried out for TRIGA-type reactor systems in which uranium-zirconium hydride fuel rods are loaded by using the continuous-energy Monte Carlo code MVP with the evaluated nuclear data library JENDL-5. The analyses cover two sorts of benchmark data, the IEU-COMP-THERM-003 and IEU-COMP-THERM-013 in the International Criticality Safety Benchmark Evaluation Project (ICSBEP) Handbook, and effective neutron multiplication factors, reactivity worths for control rods etc. were calculated by JENDL-5 in comparison with those by the previous version of JENDL. As the results, it was confirmed that the effective neutron multiplication factors obtained by JENDL-5 were 0.4 to 0.6% greater than those by JENDL-4.0, and that there were no significant differences in the calculated reactivity worths by between JENDL-5 and JENDL-4.0. Those results are considered to be helpful for the confirmation of calculation accuracy in the analyses on NSRR control rod worths, which are planned in the future.

Journal Articles

Development of dynamic PRA methodology for external hazards (Application of CMMC method to severe accident analysis code)

Li, C.-Y.; Watanabe, Akira*; Uchibori, Akihiro; Okano, Yasushi

Dai-26-Kai Doryoku, Enerugi Gijutsu Shimpojiumu Koen Rombunshu (Internet), 4 Pages, 2022/07

Identifying accident scenarios that could lead to severe accidents and evaluating their frequency of occurrence are essential issues. This study aims to establish the methodology of the dynamic Probabilistic Risk Assessment (PRA) for sodium-cooled fast reactors that can consider the time dependency and the interdependence of each event. Specifically, the Continuous Markov chain Monte Carlo (CMMC) method is newly applied to the SPECTRA code, which analyzes the severe accident conditions of nuclear reactors, to develop an evaluation methodology for typical external hazards. Currently, a fault-tree model of air coolers of decay heat removal system is implemented as the CMMC method, and a series of preliminary analysis of the plant's transient characteristics under the scenario of volcanic ashfall has been conducted.

Journal Articles

OECD/NEA benchmark on pellet-clad mechanical interaction modelling with fuel performance codes; Influence of pellet geometry and gap size

Soba, A.*; Prudil, A.*; Zhang, J.*; Dethioux, A.*; Han, Z.*; Dostal, M.*; Matocha, V.*; Marelle, V.*; Lasnel-Payan, J.*; Kulacsy, K.*; et al.

Proceedings of TopFuel 2021 (Internet), 10 Pages, 2021/10

Journal Articles

Nuclear data processing code FRENDY; A Verification with HTTR criticality benchmark experiments

Fujimoto, Nozomu*; Tada, Kenichi; Ho, H. Q.; Hamamoto, Shimpei; Nagasumi, Satoru; Ishitsuka, Etsuo

Annals of Nuclear Energy, 158, p.108270_1 - 108270_8, 2021/08

 Times Cited Count:3 Percentile:30.71(Nuclear Science & Technology)

JAEA Reports

Proceedings of the 2019 Symposium on Nuclear Data; November 28-30, 2019, Kyushu University, Chikushi Campus, Fukuoka, Japan

Watanabe, Yukinobu*; Shigyo, Nobuhiro*; Kin, Tadahiro*; Iwamoto, Osamu

JAEA-Conf 2020-001, 236 Pages, 2020/12

JAEA-Conf-2020-001.pdf:13.75MB

The 2019 Symposium on Nuclear Data was held at Chikushi Campus Cooperation Building (C-Cube), Kyushu University, on November 28 to 30, 2019. The symposium was organized by the Nuclear Data Division of the Atomic Energy Society of Japan (AESJ) in cooperation with Sigma Investigative Advisory Committee of AESJ, Nuclear Science and Engineering Center of Japan Atomic Energy Agency, Kyushu Branch of AESJ, and Center for Accelerator and Beam Applied Science of Kyushu University. In the symposium, there were one tutorial, "From the resonance theory to statistical model", and five sessions, "Study on Nuclear Data and related topics", "Reactor physics", "International Cooperation", "Nuclear Physics", and "High Energy Nuclear Data and their Application". In addition, recent research progress on experiments, nuclear theory, evaluation, benchmark and applications was presented in the poster session. Among 85 participants, all presentations and following discussions were very active and fruitful. This report consists of total 42 papers including 13 oral and 29 poster presentations.

Journal Articles

Special issue on accelerator-driven system benchmarks at Kyoto University Critical Assembly

Pyeon, C. H.*; Talamo, A.*; Fukushima, Masahiro

Journal of Nuclear Science and Technology, 57(2), p.133 - 135, 2020/02

 Times Cited Count:4 Percentile:96.32(Nuclear Science & Technology)

JAEA Reports

Proceedings of the 2018 Symposium on Nuclear Data; November 29-30, 2018, Tokyo Institute of Technology, Ookayama Campus, Tokyo, Japan

Chiba, Satoshi*; Ishizuka, Chikako*; Tsubakihara, Kosuke*; Iwamoto, Osamu

JAEA-Conf 2019-001, 203 Pages, 2019/11

JAEA-Conf-2019-001.pdf:18.86MB

The 2018 Symposium on Nuclear Data was held at Multi-Purpose Digital Hall and Collaboration Room of Tokyo Institute of Technology, on November 29 and 30, 2018. The symposium was organized by the Nuclear Data Division of the Atomic Energy Society of Japan (AESJ) in cooperation with Sigma Special Committee of AESJ, Nuclear Science and Engineering Center of Japan Atomic Energy Agency, and Laboratory for Advanced Nuclear Energy of Institute of Innovative Research, Tokyo Institute of Technology. In the symposium, there were one tutorial, "Development of nuclear data processing code FRENDY", one special lecture "What the future holds for Nuclear Energy" and seven oral sessions, "Nuclear Data and Future Perspectives", "Current Status and Future Perspectives of Reactor Physics", "Topics", "Nuclear Data Applications", "International Session", "Nuclear Data Measurements and New Technology for Nuclear Reactor Diagnosis", and "Data Needs from New Fields". In addition, recent research progress on experiments, evaluation, benchmark and application was presented in the poster session. Among 82 participants, all presentations and following discussions were very active and fruitful. This report consists of total 35 papers including 13 oral and 22 poster presentations.

Journal Articles

Benchmark of fuel performance codes for FeCrAl cladding behavior analysis

Pastore, G.*; Gamble, K. A.*; Cherubini, M.*; Giovedi, C.*; Marino, A.*; Yamaji, Akifumi*; Kaji, Yoshiyuki; Van Uffelen, P.*; Veshchunov, M.*

Proceedings of International Nuclear Fuel Cycle Conference / Light Water Reactor Fuel Performance Conference (Global/Top Fuel 2019) (USB Flash Drive), p.1038 - 1047, 2019/09

Oxidation-resistant iron-chromium-aluminum (FeCrAl) steels have been proposed for application as cladding materials in light water reactor fuel rods with improved accident tolerance. Within the Coordinated Research Project ACTOF of the International Atomic Energy Agency (IAEA), a fuel performance modeling benchmark for FeCrAl cladding behavior was conducted. During this effort, calculations were performed with various fuel performance codes for a set of fuel rod problems with FeCrAl steel as cladding material, and results were compared to each other.

Journal Articles

ACE library of JENDL-4.0/HE

Matsuda, Norihiro; Kunieda, Satoshi; Okamoto, Tsutomu*; Tada, Kenichi; Konno, Chikara

Progress in Nuclear Science and Technology (Internet), 6, p.225 - 229, 2019/01

Journal Articles

Stratification break-up by a diffuse buoyant jet; A CFD benchmark exercise

Studer, E.*; Abe, Satoshi; Andreani, M.*; Bharj, J. S.*; Gera, B.*; Ishay, L.*; Kelm, S.*; Kim, J.*; Lu, Y.*; Paliwal, P.*; et al.

Proceedings of 12th International Topical Meeting on Nuclear Reactor Thermal-Hydraulics, Operation and Safety (NUTHOS-12) (USB Flash Drive), 16 Pages, 2018/10

232 (Records 1-20 displayed on this page)