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Iwamoto, Osamu; Iwamoto, Nobuyuki; Kunieda, Satoshi; Minato, Futoshi; Nakayama, Shinsuke; Kimura, Atsushi; Nakamura, Shoji; Endo, Shunsuke; Nagaya, Yasunobu; Tada, Kenichi; et al.
EPJ Web of Conferences, 284, p.14001_1 - 14001_7, 2023/05
Tada, Kenichi; Nagaya, Yasunobu; Taninaka, Hiroshi; Yokoyama, Kenji; Okita, Shoichiro; Oizumi, Akito; Fukushima, Masahiro; Nakayama, Shinsuke
Journal of Nuclear Science and Technology, p.1 - 21, 2023/04
Times Cited Count：0 Percentile：0.02(Nuclear Science & Technology)The new version of the Japanese evaluated nuclear data library, JENDL-5, was released in December 2021. This paper demonstrates the validation of JENDL-5 for fission reactor applications. Benchmark calculations are performed with the continuous-energy Monte Carlo codes MVP and MCNP and the deterministic code system MARBLE. The benchmark calculation results indicate that the performance of JENDL-5 for fission reactor applications is better than that of the former library JENDL-4.0.
Tada, Kenichi; Yamamoto, Akio*; Kunieda, Satoshi; Nagaya, Yasunobu
JAEA-Data/Code 2022-009, 208 Pages, 2023/02
JAEA-Data-Code-2022-009.pdf:3.87MB
The nuclear data processing code has an important role to connect evaluated nuclear data libraries and neutronics calculation codes. Japan Atomic Energy Agency (JAEA) has developed the nuclear data processing code FRENDY since 2013 to generate cross section files from evaluated nuclear data libraries, such as JENDL, ENDF/B, JEFF, and TENDL. The first version of FRENDY was released in 2019. FRENDY version 1 generates ACE files which are used for continuous energy Monte Carlo codes such as PHITS, Serpent, and MCNP. FRENDY version 2 generates multi-group neutron cross-section files from ACE files. The other major improvements are as follows: (1) uncertainty quantification for the probability tables of the unresolved resonance cross-section; (2) perturbation of the ACE file for the uncertainty quantification using a continuous Monte Carlo code; (3) modification of the ENDF-6 formatted nuclear data file. This report describes an overview of the nuclear data processing methods and input instructions for FRENDY.
Iwamoto, Osamu; Iwamoto, Nobuyuki; Kunieda, Satoshi; Minato, Futoshi; Nakayama, Shinsuke; Abe, Yutaka*; Tsubakihara, Kosuke*; Okumura, Shin*; Ishizuka, Chikako*; Yoshida, Tadashi*; et al.
Journal of Nuclear Science and Technology, 60(1), p.1 - 60, 2023/01
Times Cited Count：17 Percentile：99.95(Nuclear Science & Technology)Kamiya, Tomohiro; Ono, Ayako; Tada, Kenichi; Akie, Hiroshi; Nagaya, Yasunobu; Yoshida, Hiroyuki; Kawanishi, Tomohiro
Proceedings of 29th International Conference on Nuclear Engineering (ICONE 29) (Internet), 8 Pages, 2022/11
JAEA started to develop the advanced reactor analysis code JAMPAN (JAEA advanced multi-physics analysis platform for nuclear systems). The current version of JAMPAN handles the continuous energy Monte Carlo code MVP and the detailed thermal-hydraulics analysis code for multiphase and multicomponent JUPITER. JAMPAN is designed to consider the extensibility and it does not depend on the analysis codes. All calculations in JAMAPAN are not directly connected. JAMPAN has data containers, and all input and output data of each analysis code are set in these data containers. JAMPAN will easily exchange the calculation codes and add the other calculations, e.g., structure calculation and irradiation calculation since the input and the output format of each code has no impact on the other calculation codes. The 4 by 4 pin-cell geometry was used as the demonstration calculation of JAMPAN and the physically reasonable calculation results were obtained.
-eigenvalue perturbation in Monte Carlo calculationTuya, D.; Nagaya, Yasunobu
Annals of Nuclear Energy, 169, p.108919_1 - 108919_9, 2022/05
Times Cited Count：1 Percentile：49.42(Nuclear Science & Technology)Estimating an effect of a perturbation in a fissile system on its -eigenvalue requires special technique called perturbation theory when the considered perturbation is small. In this study, we develop an adjoint-weighted correlated sampling (AWCS) method based on the exact perturbation theory without any approximation by combining the correlated sampling (CS) method with iterated-fission probability (IFP) based adjoint-weighting method. With the advantages of the CS method being good at providing very small uncertainty for small perturbations and the IFP-based adjoint-weighting method being suitable for continuous-energy Monte Carlo calculation, the developed AWCS method based on the exact perturbation theory offers a new rigorous approach for perturbation calculations. The obtained results by the developed AWCS method for verification problems involving Godiva and simplified STACY density perturbations showed good agreement with the reference calculations.
Okita, Shoichiro; Nagaya, Yasunobu; Fukaya, Yuji
Journal of Nuclear Science and Technology, 58(9), p.992 - 998, 2021/09
Times Cited Count：2 Percentile：41.01(Nuclear Science & Technology)Nagaya, Yasunobu; Ueki, Taro; Tonoike, Kotaro
Proceedings of 11th International Conference on Nuclear Criticality Safety (ICNC 2019) (Internet), 9 Pages, 2019/09
A new Monte Carlo solver Solomon has been developed for the application to fuel-debris systems. It is designed not only for usual criticality safety analysis but also for criticality calculations of damaged reactor core including fuel debris. This paper describes the current status of Solomon and demonstrates the applications of the randomized Weierstrass function (RWF) model and the RWF model superimposed voxel geometry.
Tonoike, Kotaro; Watanabe, Tomoaki; Gunji, Satoshi; Yamane, Yuichi; Nagaya, Yasunobu; Umeda, Miki; Izawa, Kazuhiko; Ogawa, Kazuhiko
Proceedings of 11th International Conference on Nuclear Criticality Safety (ICNC 2019) (Internet), 9 Pages, 2019/09
Criticality control of the fuel debris in the Fukushima Daiichi Nuclear Power Station would be a risk-informed control to mitigate consequences of criticality events, instead of a deterministic control to prevent such events. The Nuclear Regulation Authority of Japan has administrated a research and development program to tackle this challenge since 2014. The Nuclear Safety Research Center of Japan Atomic Energy Agency, commissioned by the authority, is conducting activities such as computations of criticality characteristics of the fuel debris, development of a criticality analysis code, preparation of criticality experiments, and development of a criticality risk analysis method.
Yokoyama, Kenji; Sugino, Kazuteru; Ishikawa, Makoto; Maruyama, Shuhei; Nagaya, Yasunobu; Numata, Kazuyuki*; Jin, Tomoyuki*
JAEA-Research 2018-011, 556 Pages, 2019/03
JAEA-Research-2018-011.pdf:19.53MB
JAEA-Research-2018-011-appendix1(DVD-ROM).zip:433.07MBJAEA-Research-2018-011-appendix2(DVD-ROM).zip:580.12MBJAEA-Research-2018-011-appendix3(DVD-ROM).zip:9.17MB
We have developed a new unified cross-section set ADJ2017, which is an improved version of the unified cross-section set ADJ2010 for fast reactors. The unified cross-section set is used for reflecting information of C/E values (analysis / experiment values) obtained by integral experiment analyses; the values are stored in the standard database for FBR core design via the cross-section adjustment methodology, which integrates with the information such as uncertainty (covariance) of nuclear data, uncertainty of integral experiment / analysis, sensitivity of integral experiment with respect to nuclear data. The ADJ2017 is based on Japan's latest nuclear data library JENDL-4.0 as in the previous version of ADJ2010, and it incorporates more information on integral experimental data sets related to minor actinides (MAs) and degraded plutonium (Pu). In the creation of ADJ2010, a total of 643 integral experimental data sets were analyzed and evaluated, and 488 of the integral experimental data sets were finally selected to be used for the cross-section adjustment. In contrast, we have evaluated a total of 719 data sets, and eventually adopted 620 integral experimental data sets to create ADJ2017. ADJ2017 shows almost the same performance as ADJ2010 for the main neutronic characteristics of conventional sodium-cooled MOX-fuel fast reactors. In addition, for the neutronic characteristics related to MA and degraded Pu, ADJ2017 improves the C/E values of the integral experimental data sets, and reduces the uncertainty induced by the nuclear data. ADJ2017 is expected to be widely used in the analysis and design research of fast reactors. Moreover, it is expected that the integral experimental data sets used for ADJ2017 can be utilized as a standard database of FBR core design.
Tada, Kenichi; Kunieda, Satoshi; Nagaya, Yasunobu
JAEA-Data/Code 2018-014, 106 Pages, 2019/01
JAEA-Data-Code-2018-014.pdf:1.76MBJAEA-Data-Code-2018-014-appendix(DVD-ROM).zip:6.99MB
A new nuclear data processing code FRENDY has been developed in order to process the evaluated nuclear data library JENDL. Development of FRENDY helps to disseminate JENDL and various nuclear calculation codes. FRENDY is developed not only to process the evaluated nuclear data file but also to implement the FRENDY functions to other calculation codes. Users can easily use many functions e.g., read, write, and process the evaluated nuclear data file, in their own codes when they implement the classes of FRENDY to their codes. FRENDY is coded with considering maintainability, modularity, portability and flexibility. The processing method of FRENDY is similar to that of NJOY. The current version of FRENDY treats the ENDF-6 format and generates the ACE file which is used for the continuous energy Monte Carlo codes such as PHITS and MCNP. This report describes the nuclear data processing methods and input instructions for FRENDY.
Tada, Kenichi; Nagaya, Yasunobu; Kunieda, Satoshi; Suyama, Kenya; Fukahori, Tokio
EPJ Web of Conferences, 146, p.02028_1 - 02028_5, 2017/09
Times Cited Count：3 Percentile：87.62JAEA has started to develop new nuclear data processing system FRENDY (FRom Evaluated Nuclear Data libralY to any application). In this presentation, the outline of the development of FRENDY is presented. And functions and performances of FRENDY are demonstrated by generation and validation of the continuous energy cross section data libraries for MVP, PHITS and MCNP codes.
Tada, Kenichi; Nagaya, Yasunobu; Kunieda, Satoshi; Suyama, Kenya; Fukahori, Tokio
Journal of Nuclear Science and Technology, 54(7), p.806 - 817, 2017/07
Times Cited Count：41 Percentile：97.99(Nuclear Science & Technology)JAEA has developed an evaluated nuclear data library JENDL and several nuclear analysis codes such as MARBLE2, SRAC, MVP and PHITS. Though JENDL and these computer codes have been widely used in many countries, the nuclear data processing system to generate the data library for application programs had not been developed in Japan and foreign nuclear data processing systems, e.g., NJOY and PREPRO are used. To process the new library for JAEA's computer codes immediately and independently, JAEA started to develop the new nuclear data processing system FRENDY in 2013. In this paper, outline, function, and verification of FRENDY are described.
Nagaya, Yasunobu
Hoshasen, 43(2), p.49 - 54, 2017/05
no abstracts in English
Ohgama, Kazuya; Ikeda, Kazumi*; Ishikawa, Makoto; Kan, Taro*; Maruyama, Shuhei; Yokoyama, Kenji; Sugino, Kazuteru; Nagaya, Yasunobu; Oki, Shigeo
Proceedings of 2017 International Congress on Advances in Nuclear Power Plants (ICAPP 2017) (CD-ROM), 10 Pages, 2017/04
Nagaya, Yasunobu; Adachi, Masaaki*
Proceedings of International Conference on Mathematics & Computational Methods Applied to Nuclear Science & Engineering (M&C 2017) (USB Flash Drive), 6 Pages, 2017/04
MVP is a general-purpose Monte Carlo code for neutron and photon transport calculations based on the continuous-energy method. To speed up the MVP code, hybrid parallelization is applied with a message passing interface library MPI and a shared-memory multiprocessing library OpenMP. The performance test has been done for an eigenvalue calculation of a fast reactor subassembly, a fixed-source calculation of a neutron/photon coupled problem and a PWR full core model. Comparisons has been made for MPI only with 4 processes and hybrid parallelism with 4 processes 
3 threads. As a result, the hybrid parallelism yields the reduction of elapsed time by 16% to 34% and the used memories are almost the same.
Kuwagaki, Kazuki*; Nagaya, Yasunobu
JAEA-Data/Code 2017-007, 27 Pages, 2017/03
JAEA-Data-Code-2017-007.pdf:4.77MBJAEA-Data-Code-2017-007-appendix(CD-ROM).zip:0.37MB
The integral benchmark test of JENDL-4.0 for U-233 systems using the continuous-energy Monte Carlo code MVP was conducted. The previous benchmark test was performed only for U-233 thermal solution and fast metallic systems in the ICSBEP handbook. In this study, MVP input files were prepared for uninvestigated benchmark problems in the handbook including compound thermal systems (mainly lattice systems) and integral benchmark test was performed. The prediction accuracy of JENDL-4.0 was evaluated for effective multiplication factors (
's) of the U-233 systems. As a result, a trend of underestimation was observed for all the categories of U-233 systems. In the benchmark test of ENDF/B-VII.1 for U-233 systems with the ICSBEP handbook, it is reported that a decreasing trend of calculated values in association with a parameter ATFF (Above-Thermal Fission Fraction) is observed. The ATFF values were also calculated in this benchmark test of JENDL-4.0 and the same trend as ENDF/B-VII.1 was observed.
Nagaya, Yasunobu; Okumura, Keisuke; Sakurai, Takeshi; Mori, Takamasa
JAEA-Data/Code 2016-019, 450 Pages, 2017/03
JAEA-Data-Code-2016-019.pdf:4.43MBJAEA-Data-Code-2016-019-hyperlink.zip:2.36MB
In order to realize fast and accurate Monte Carlo simulation of neutron and photon transport problems, two Monte Carlo codes MVP (continuous-energy method) and GMVP (multigroup method) have been developed at Japan Atomic Energy Agency. The codes have adopted a vectorized algorithm and have been developed for vector-type supercomputers. They also support parallel processing with a standard parallelization library MPI and thus a speed-up of Monte Carlo calculations can be achieved on general computing platforms. The first and second versions of the codes were released in 1994 and 2005, respectively. They have been extensively improved and new capabilities have been implemented. The major improvements and new capabilities are as follows: (1) perturbation calculation for effective multiplication factor, (2) exact resonant elastic scattering model, (3) calculation of reactor kinetics parameters, (4) photo-nuclear model, (5) simulation of delayed neutrons, (6) generation of group constants, etc. This report describes the physical model, geometry description method used in the codes, new capabilities and input instructions.
Nagaya, Yasunobu; Okumura, Keisuke; Sakurai, Takeshi; Mori, Takamasa
JAEA-Data/Code 2016-018, 421 Pages, 2017/03
JAEA-Data-Code-2016-018.pdf:3.89MBJAEA-Data-Code-2016-018-appendix(CD-ROM).zip:4.02MBJAEA-Data-Code-2016-018-hyperlink.zip:1.94MB
In order to realize fast and accurate Monte Carlo simulation of neutron and photon transport problems, two Monte Carlo codes MVP (continuous-energy method) and GMVP (multigroup method) have been developed at Japan Atomic Energy Agency. The codes have adopted a vectorized algorithm and have been developed for vector-type supercomputers. They also support parallel processing with a standard parallelization library MPI and thus a speed-up of Monte Carlo calculations can be achieved on general computing platforms. The first and second versions of the codes were released in 1994 and 2005, respectively. They have been extensively improved and new capabilities have been implemented. The major improvements and new capabilities are as follows: (1) perturbation calculation for effective multiplication factor, (2) exact resonant elastic scattering model, (3) calculation of reactor kinetics parameters, (4) photo-nuclear model, (5) simulation of delayed neutrons, (6) generation of group constants, etc. This report describes the physical model, geometry description method used in the codes, new capabilities and input instructions.
U for CIELO project using integral experiments of uranium-fueled FCA assembliesFukushima, Masahiro; Kitamura, Yasunori*; Yokoyama, Kenji; Iwamoto, Osamu; Nagaya, Yasunobu; Leal, L. C.*
Proceedings of International Conference on the Physics of Reactors; Unifying Theory and Experiments in the 21st Century (PHYSOR 2016) (USB Flash Drive), p.605 - 619, 2016/05
A nuclear data of U has been recently evaluated for the CIELO (Collaborative International Evaluated Library Organization) project. We tested the newly-evaluated data of U using integral experiments of the Fast Critical Assembly (FCA) performed at JAEA. We selected two integral data of uranium-fueled FCA assemblies; one is the sodium-void reactivity worth of FCA XXVII-1 assembly and the other is the criticalities of the seven assemblies of FCA IX. The benchmark tests support the evaluation done in the resonance regions. However, the U capture cross section above the unresolved resonance range needs further investigation.
