Development of the ghost fluid method satisfying conservation laws for liquid-gas flow with shock wave

Kamiya, Tomohiro; Yoshida, Hiroyuki

Proceedings of the Symposium on Shock Waves in Japan (Internet), 7 Pages, 2024/03

We developed a ghost fluid method satisfying conservation laws to simulate steam explosions that can occur at the accident of a nuclear power plant. In the developed method, a first-order approximation is applied to interface effect regions, and a high-order approximation is applied to bulk regions. In other words, the algorithm of the developed method is not consistent. Therefore, we modify the way of getting ghost fluids and propose a comprehensive algorithm that applies a high-order approximation to interface effect regions. In the presentation, we will report the outlines and results of the numerical tests of it.

Numerical interpretation of thermal desorption spectra of hydrogen from high-carbon ferrite-austenite dual-phase steel

Ebihara, Kenichi; Sekine, Daiki*; Sakiyama, Yuji*; Takahashi, Jun*; Takai, Kenichi*; Omura, Tomohiko*

International Journal of Hydrogen Energy, 48(79), p.30949 - 30962, 2023/09

https://doi.org/10.1016/j.ijhydene.2023.04.205

To understand hydrogen embrittlement (HE), which is one of the stress corrosion cracking of steel materials, it is necessary to know the H distribution in steel, which can be effectively interpreted by numerical simulation of thermal desorption spectra. In weld metals and TRIP steels, residual austenite significantly influences the spectra, but a clear H distribution is not well known. In this study, an originally coded two-dimensional model was used to numerically simulate the previously reported spectra of high-carbon ferritic-austenitic duplex stainless steels, and it was found that H is mainly trapped at the carbide surface when the amount of H in the steel is low and at the duplex interface when the amount of H is high. It was also found that the thickness dependence of the H desorption peak for the interface trap site is caused by a different reason than the conventional one.

Experiment and numerical simulation of pulsation flow in single channel for Li-7 enrichment technology development by MCCCE method

Horiguchi, Naoki; Yoshida, Hiroyuki; Kitatsuji, Yoshihiro; Hasegawa, Makoto*; Kishimoto, Tadafumi*

Proceedings of 30th International Conference on Nuclear Engineering (ICONE30) (Internet), 7 Pages, 2023/05

From the viewpoint of energy security in Japan and reduction of the environmental load, continuous operation of light water reactors is essential. Since a pH adjuster with enriched Li-7 ions is required for water quality control on PWR, the development of Li-7 enrichment technology is one of the key issues. The multi-channel counter-current electrophoresis (MCCCE) method has been developed as the technology with a low environmental load. To put this method into practical use, it is necessary to understand Li-7 ion behavior in the channel flow and optimize the experimental condition to separate Li-7 and its isotope. In this paper, to understand Li-7 ion behavior in a single channel of the experimental apparatus, a numerical simulation method based on a computational fluid dynamics (CFD) code with a particle tracking method, TPFIT-LPT, was developed. In the method, the motion of multiple ions under the electric field was simulated as a particle with an added velocity by the electric field. The difference in the isotopes was represented by changing of the magnitude of the added velocity. We also considered that although it is impossible to measure the behavior of each ion, it is important to measure the flow velocity of the bulk fluid for the validation of the numerical simulation. We developed a lab-scale experimental apparatus in which the single channel of the actual apparatus was simplified to measure the flow velocity by Particle Image Velocimetry (PIV). We set a pulsation flow condition on the lab-scale experiment, which is one of difficult conditions for the numerical simulation, and measured the velocity. As the result, we confirmed that the pulsation flow was reproduced. We set the measured data as the inlet boundary condition of the numerical simulation and conducted it. As the numerical result, we confirmed the ions affected by the electric field moved upstream with pulsation. We also confirmed the effect of the electric field on the motion of the isotope.

ARKADIA; For the innovation of advanced nuclear reactor design

Ohshima, Hiroyuki; Asayama, Tai; Furukawa, Tomohiro; Tanaka, Masaaki; Uchibori, Akihiro; Takata, Takashi; Seki, Akiyuki; Enuma, Yasuhiro

Journal of Nuclear Engineering and Radiation Science, 9(2), p.025001_1 - 025001_12, 2023/04

https://doi.org/10.1115/1.4054726

This paper describes the outline and development plan for ARKADIA to transform advanced nuclear reactor design to meet expectations of a safe, economic, and sustainable carbon-free energy source. ARKADIA will realize Artificial Intelligence (AI)-aided integrated numerical analysis to offer the best possible solutions for the design and operation of a nuclear plant, including optimization of safety equipment. State-of-the-art numerical simulation technologies and a knowledge base that stores data and insights from past nuclear reactor development projects and R&D are integrated with AI. In the first phase of development, ARKADIA-Design and ARKADIA-Safety will be constructed individually, with the first target of sodium-cooled reactor. In a subsequent phase, everything will be integrated into a single entity applicable not only to advanced rectors with a variety of concepts, coolants, configurations, and output levels but also to existing light-water reactors.

A Preliminary validation study for removal performance of iodine gas in sodium pool with a simplified approach

Kam, D. H.*; Grabaskas, D.*; Starkus, T.*; Bucknor, M.*; Uchibori, Akihiro

Transactions of the American Nuclear Society, 126(1), p.536 - 539, 2022/06

https://doi.org/10.13182/T126-38052

Removal of gaseous radionuclides from the bubbles released into the sodium pool is an important consideration of fuel pin failure accident in sodium-cooled fast reactors. To support modeling of this phenomenon as a part of development of the SRT (Simplified Radionuclide Transport) code in Argonne National Laboratory, numerical analysis of experiment on Iodine gas transport to sodium pool was performed. A proposed evaluation method can be regarded to be reasonably predicting the measured decontamination factors.

Evaluation and analysis method of hydrogen embrittlement, 3; Interpretation of thermal desorption profiles of hydrogen based on numerical simulations

Ebihara, Kenichi

Zairyo, 71(5), p.481 - 487, 2022/05

https://doi.org/10.2472/jsms.71.481

no abstracts in English

Calculation code of output current for self-powered radiation detector; Algorithm construction and comparison of calculation results

Shibata, Hiroshi; Takeuchi, Tomoaki; Seki, Misaki; Shibata, Akira; Nakamura, Jinichi; Ide, Hiroshi

JAEA-Data/Code 2021-018, 42 Pages, 2022/03

JAEA-Data-Code-2021-018.pdf:2.78MB
JAEA-Data-Code-2021-018-appendix(CD-ROM).zip:0.15MB

Japan Materials Testing Reactor (JMTR) in Oarai Research and Development Institute of the Japan Atomic Energy Agency has been developing various reactor materials, irradiation techniques and instruments for more than 30 years. Among them, the development of self-powered neutron detectors (SPNDs) and gamma detectors (SPGDs) has been carried out, and several research results have been reported. However, most of the results are based on the design study of the detector development and the results of in-core irradiation tests and gamma irradiation tests using Cobalt-60. In this report, a numerical code is developed based on the paper "Neutron and Gamma-Ray Effects on Self-Powered In-Core Radiation Detectors" written by H.D. Warren and N.H. Shah in 1974, in order to theoretically evaluate the self-powered radiation detectors.

Evaluation on laser quenching heat transfer mechanism using numerical method and improvement of quenching depth

Kitagawa, Yoshihiro; Shirahama, Takuma*; Kisohara, Naoyuki; Tsuboi, Akihiko

Dai-96-Kai Reza Kako Gakkai Koen Rombunshu (Internet), p.91 - 96, 2022/01

Laser scanning quenching is a locally and rapidly heat-treated process and has an advantage of no coolant required. Compared with conventional technique such as induction quenching, the region of laser quenching is about 0.50.7mm in depth and it needs to be expanded for more applications or durability. For this purpose, the temperature distributions and transitions in materials during laser irradiation have been revealed by using a 3D heat transfer computer code, micro-structural observation and hardness transitions in depth direction. The results indicate the laser irradiation with low power and low scan speed condition allows deeper quenching area, but it also suggests the hardness of the deepest quenching area is degraded due to slow temperature decreasing rate after laser heat scanning. Multiple times continuous irradiation have been proposed and studied to resolve this hardness degradation, and maximum quenching depth of 1.4mm is obtained under three times irradiation and controlling its power and scan speed properly.

Estimation of the core degradation and relocation at the Fukushima Daiichi Nuclear Power Station Unit 2 based on RELAP/SCDAPSIM analysis

Madokoro, Hiroshi; Sato, Ikken

Nuclear Engineering and Design, 376, p.111123_1 - 111123_15, 2021/05

https://doi.org/10.1016/j.nucengdes.2021.111123

Evaluation of the characteristics of metal nitrate aqueous solutions by microwave heating and the morphologies of synthesized metal oxide powders

Segawa, Tomoomi; Kawaguchi, Koichi; Ishii, Katsunori; Suzuki, Masahiro; Fukasawa, Tomonori*; Fukui, Kunihiro*

Funtai Kogakkai-Shi, 57(9), p.485 - 494, 2020/09

In the spent fuel reprocessing process, a mixed solution of uranyl nitrate and plutonium nitrate is converted into mixed oxide powder by the microwave heating. To evaluate the applicability to the industrial-scale and acquire the characteristics data of the microwave heating denitration of various metal nitrate aqueous solutions based on the knowledge studied in the development of laboratory-scale basic experiments, the microwave heating characteristics and metal oxide powder properties were investigated using cerium nitrate, cobalt nitrate and copper nitrate aqueous solutions. The progress rate of the denitration reaction was depended on the position, and the denitration reaction proceeded faster at the periphery than at the center. The morphologies of the synthesized products were porous and hard dry solid with cerium nitrate aqueous solution, foamed dry solid with cobalt nitrate aqueous solution, and powdery particles with copper nitrate aqueous solution. The denitration ratio and average particle size of the synthesized products increased in the order of the cerium nitrate aqueous solution, the cobalt nitrate aqueous solution, and the copper nitrate aqueous solution. The numerical simulations revealed that the periphery of the bottom surface of the metal nitrate aqueous solution was heated by microwaves. This results consistent with the experimental results in which the denitration reaction started from the periphery of the metal nitrate aqueous solution.