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Journal Articles

Validation practices of multi-physics core performance analysis in an advanced reactor design study

Doda, Norihiro; Kato, Shinya; Hamase, Erina; Kuwagaki, Kazuki; Kikuchi, Norihiro; Ohgama, Kazuya; Yoshimura, Kazuo; Yoshikawa, Ryuji; Yokoyama, Kenji; Uwaba, Tomoyuki; et al.

Proceedings of 20th International Topical Meeting on Nuclear Reactor Thermal Hydraulics (NURETH-20) (Internet), p.946 - 959, 2023/08

An innovative design system named ARKADIA is being developed to realize the design of advanced nuclear reactors as safe, economical, and sustainable carbon-free energy sources. This paper focuses on ARKADIA-Design for design studies as a part of ARKADIA and introduces representative verification methods for numerical analysis methods of the core design. ARKADIA-Design performs core performance analysis of sodium-cooled fast reactors using a multiphysics approach that combines neutronics, thermal-hydraulics, core mechanics, and fuel pin behavior analysis codes. To confirm the validity of these analysis codes, validation matrices are identified with reference to experimental data and reliable numerical analysis results. The analysis models in these codes and the representative practices for the validation matrices are described.

Journal Articles

Investigation of optimization process for core design with integrated analysis between neutronics and plant dynamics

Hamase, Erina; Kuwagaki, Kazuki; Doda, Norihiro; Yokoyama, Kenji; Tanaka, Masaaki

Proceedings of 30th International Conference on Nuclear Engineering (ICONE30) (Internet), 10 Pages, 2023/05

To innovate a core design process, an optimization process for the core design has been developed as a part of the design optimization support tool named ARKADIA-Design. The core design optimization process is integrated by the core design analysis of neutronics, thermal-hydraulics, and fuel integrity and plant dynamics analysis with the Bayesian optimization (BO) algorithm. The optimization problem for design parameters with high core performance and inherent safety in ULOF event was solved by the integrated analysis between the neutronics and plant dynamics with the BO in a primary loop system including a core consisting of two-dimensional RZ cylindrical geometry. It was indicated that the optimization process could obtain an optimal solution.

Journal Articles

Development of ARKADIA-Design for design optimization support; Application of coupling method using multi-level simulation technique for plant thermal-hydraulics analysis

Doda, Norihiro; Yoshimura, Kazuo; Hamase, Erina; Yokoyama, Kenji; Uwaba, Tomoyuki; Tanaka, Masaaki

Proceedings of Technical Meeting on State-of-the-art Thermal Hydraulics of Fast Reactors (Internet), 3 Pages, 2022/09

ARKADIA-Design is being developed to support the optimization of sodium-cooled fast reactors in the conceptual design stage. Design optimization requires various types of numerical analysis: 1-D plant dynamics analysis for efficient evaluation of various design options and multi-dimensional analysis for a detailed evaluation of local phenomena, including multi-physics. For those analyses, ARKADIA-Design performs whole plant analyses based on the multi-level simulation (MLS) technique in which the analysis codes are coupled to simulate the phenomena in an intended degree of resolution. This paper describes an outline of the coupling analysis methods in the MLS of the ARKADIA-Design and the numerical simulations of the experimental fast breeder reactor EBR-II tests by the coupled analysis.

Journal Articles

Sodium-cooled Fast Reactors

Ohshima, Hiroyuki; Morishita, Masaki*; Aizawa, Kosuke; Ando, Masanori; Ashida, Takashi; Chikazawa, Yoshitaka; Doda, Norihiro; Enuma, Yasuhiro; Ezure, Toshiki; Fukano, Yoshitaka; et al.

Sodium-cooled Fast Reactors; JSME Series in Thermal and Nuclear Power Generation, Vol.3, 631 Pages, 2022/07

This book is a collection of the past experience of design, construction, and operation of two reactors, the latest knowledge and technology for SFR designs, and the future prospects of SFR development in Japan. It is intended to provide the perspective and the relevant knowledge to enable readers to become more familiar with SFR technology.

Journal Articles

Developing accelerator mass spectrometry capabilities for anthropogenic radionuclide analysis to extend the set of oceanographic tracers

Hain, K.*; Martschini, M.*; G$"u$lce, F.*; Honda, Maki; Lachner, J.*; Kern, M.*; Pitters, J.*; Quinto, F.*; Sakaguchi, Aya*; Steier, P.*; et al.

Frontiers in Marine Science (Internet), 9, p.837515_1 - 837515_17, 2022/03

 Times Cited Count:9 Percentile:96.71(Environmental Sciences)

Recent major advances in accelerator mass spectrometry (AMS) at the Vienna Environmental Research Accelerator (VERA) regarding detection efficiency and isobar suppression have opened possibilities for the analysis of additional long-lived radionuclides at ultra-low environmental concentrations. These radionuclides, including $$^{233}$$U, $$^{135}$$Cs, $$^{99}$$Tc and $$^{90}$$Sr, will become important for oceanographic tracer application due to their generally conservative behavior in ocean water. In particular, the isotope ratios $$^{233}$$U/$$^{236}$$U and $$^{137}$$Cs/$$^{135}$$Cs have proven to be powerful fingerprints for emission source identification as they are not affected by elemental fractionation. Improved detection efficiencies allowed us to analyze all major long-lived actinides, i.e. $$^{236}$$U, $$^{237}$$Np, $$^{239, 240}$$Pu, $$^{241}$$Am as well as the very rare $$^{233}$$U, in the same 10 L water samples of an exemplary depth profile from the northwest Pacific Ocean. Especially for $$^{90}$$Sr analysis, our new approach has already been validated for selected reference materials (e.g. IAEA-A-12) and is ready for application in oceanographic studies. We estimate that a sample volume of only (1-3) L ocean water is sufficient for $$^{90}$$Sr as well as $$^{135}$$Cs analysis, respectively.

Journal Articles

High-spin states in $$^{35}$$S

Go, Shintaro*; Ideguchi, Eiji*; Yokoyama, Rin*; Aoi, Nori*; Azaiez, F.*; Furutaka, Kazuyoshi; Hatsukawa, Yuichi; Kimura, Atsushi; Kisamori, Keiichi*; Kobayashi, Motoki*; et al.

Physical Review C, 103(3), p.034327_1 - 034327_8, 2021/03

 Times Cited Count:4 Percentile:58.42(Physics, Nuclear)

Journal Articles

Development of neutronics and thermal-hydraulics coupled analysis method on platform for design optimization in fast reactor

Doda, Norihiro; Hamase, Erina; Yokoyama, Kenji; Tanaka, Masaaki

Keisan Kogaku Koenkai Rombunshu (CD-ROM), 25, 4 Pages, 2020/06

With the aim of advancing the design optimization in fast reactors, neutronics and thermal-hydraulics coupled analysis method which can consider the temporal change of neutron flux distribution in the core has been developed. A three-dimensional neutronics analysis code and a plant dynamics analysis code are coupled on a platform using Python programing. In this report, outlines of the coupling method of analysis codes, the results of its application to the actual plant under a virtual accidental condition, and the future development is described.

Journal Articles

How different is the core of $$^{25}$$F from $$^{24}$$O$$_{g.s.}$$ ?

Tang, T. L.*; Uesaka, Tomohiro*; Kawase, Shoichiro; Beaumel, D.*; Dozono, Masanori*; Fujii, Toshihiko*; Fukuda, Naoki*; Fukunaga, Taku*; Galindo-Uribarri, A.*; Hwang, S. H.*; et al.

Physical Review Letters, 124(21), p.212502_1 - 212502_6, 2020/05

 Times Cited Count:14 Percentile:74.77(Physics, Multidisciplinary)

The structure of a neutron-rich $$^{25}$$F nucleus is investigated by a quasifree ($$p,2p$$) knockout reaction. The sum of spectroscopic factors of $$pi 0d_{5/2}$$ orbital is found to be 1.0 $$pm$$ 0.3. The result shows that the $$^{24}$$O core of $$^{25}$$F nucleus significantly differs from a free $$^{24}$$O nucleus, and the core consists of $$sim$$35% $$^{24}$$O$$_{rm g.s.}$$, and $$sim$$65% excited $$^{24}$$O. The result shows that the $$^{24}$$O core of $$^{25}$$F nucleus significantly differs from a free $$^{24}$$O nucleus. The result may infer that the addition of the $$0d_{5/2}$$ proton considerably changes the neutron structure in $$^{25}$$F from that in $$^{24}$$O, which could be a possible mechanism responsible for the oxygen dripline anomaly.

Journal Articles

Superdeformation in $$^{35}$$S

Go, Shintaro*; Ideguchi, Eiji*; Yokoyama, Rin*; Kobayashi, Motoki*; Kisamori, Keiichi*; Takaki, Motonobu*; Miya, Hiroyuki*; Ota, Shinsuke*; Michimasa, Shinichiro*; Shimoura, Susumu*; et al.

JPS Conference Proceedings (Internet), 6, p.030005_1 - 030005_4, 2015/06

Oral presentation

Quantitative tracing of water-rock interactions by IR spectoroscopy; An Example of alkaline alteration of granitic rocks

Nakashima, Satoru*; Kirino, Yusuke*; Nishiyama, Naoki*; Tonoue, Ryota*; Yokoyama, Tadashi*; Nagasawa, Makoto*; Harui, Rika*; Walker, C.; Sasamoto, Hiroshi

no journal, , 

Cementitious grout material will be used to reduce groundwater inflow into the repository of high level radioactive waste. High pH solution derived from cementitious grout material may cause alteration of rock mass by grout-rock interactions. With regard to evaluation of radionuclide migration, it is important to evaluate the long-term behavior of rock mass affected by grout-rock interactions since such altered rock mass potentially affects on migration behavior (e.g., diffusion and sorption) of radionuclide. This study presents the results of identification for trace secondary minerals (alteration products) by (micro)infrared spectroscopy and determination of reaction rate constants of formation for secondary minerals.

Oral presentation

Reactive-transport evaluation for alteration of granite under alkaline conditions

Kirino, Yusuke*; Nakashima, Satoru*; Yokoyama, Tadashi*; Sasamoto, Hiroshi

no journal, , 

Cementitious grout materials will be used to reduce groundwater inflow during excavation and construction of drifts for deep geological disposal of high lever radioactive waste. High alkaline solution derived from cementitious materials could alter the host rock surrounding the engineered barriers. In the present study, the experiments of interactions between the alkaline solution and the granitic rock (10 $$times$$ 10 $$times$$ 5 mm block sample) were conducted to understand the evolution of rock properties. The surface of granitic block sample is assumed the fresh fracture surface and the inside of block sample is regarded as rock matrix. Evolution and distribution of alteration products were estimated by both the accelerated laboratory experiments and the computer simulations considering reactive-transport processes.

Oral presentation

Development of core design optimization process towards design efficiency and reduction of excessive conservativeness; Setting of representative problem and investigation of core design optimization process

Hamase, Erina; Kuwagaki, Kazuki; Doda, Norihiro; Yokoyama, Kenji; Tanaka, Masaaki

no journal, , 

To improve efficiency and innovate the core design process by decreasing the excessive conservativeness using a function of the design optimization support tool named ARKADIA-Design, firstly, the optimization process that provides the core design specifications with high core performance and inherent safety in ULOF event has been developed. The objective function in the optimization problem is set with the indexes of core performance and thermal transient loads for the simplified loop model. The problem is solved by the coupled analysis between the core design analysis and plant dynamics analysis with Bayesian optimization (BO). It was indicated that the optimization process using the neutronics and plant dynamics analysis with BO in a single objective function could obtain the optimal solution.

Oral presentation

Development of advanced reactor knowledge- and AI-aided design integration approach through the whole plant life cycle, ARKADIA, 9; Development of Linkage Functions between KMS and VLS in ARKADIA-Design

Tanaka, Masaaki; Doda, Norihiro; Hamase, Erina; Yoshimura, Kazuo; Ezure, Toshiki; Seki, Akiyuki; Yokoyama, Kenji; Miyazaki, Masashi; Oki, Shigeo

no journal, , 

Design optimization support tool named ARKADIA-Design for diverse nuclear power plant is being developed in Japan Atomic Energy Agency. In the implementation of the numerical evaluation of the plant performance and the design optimization process in ARKADIA-Design, the outline and development status of linkage functions of collecting the necessary information from and storing the results as new knowledge to the databases in the Knowledge Management System are presented.

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