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Journal Articles

Voltage drop analysis and leakage suppression design for mineral-insulated cables

Hirota, Noriaki; Shibata, Hiroshi; Takeuchi, Tomoaki; Otsuka, Noriaki; Tsuchiya, Kunihiko

Journal of Nuclear Science and Technology, 57(12), p.1276 - 1286, 2020/12

 Times Cited Count:0 Percentile:0.01(Nuclear Science & Technology)

The influence of materials of mineral-insulated (MI) cables on their electrical characteristics upon exposure to high-temperature conditions was examined via a transmission test, in the objective of achieving the stability of the potential distribution along the cable length. Occurrence of a voltage drop along the cable was confirmed for aluminum oxide (Al$$_{2}$$O$$_{3}$$) and magnesium oxide (MgO), as insulating materials of the MI cable. A finite-element method (FEM)-based analysis was performed to evaluate the leakage in the potentials, which was found at the terminal end. Voltage drop yields by the transmission test and the analysis were in good agreement for the MI cable of Al$$_{2}$$O$$_{3}$$ and MgO materials, which suggests the reproducibility of the magnitude relationship of the experimental results via the FEM analysis. To suppress the voltage drop, the same FEM analysis was conducted, the diameter of the core wires ($$d$$) and the distance between them ($$l$$) were varied. Considering the variation of $$d$$, the potential distribution in the MI cable produced a minimum voltage drop corresponding to a ratio $$d/D$$ of 0.35, obtained by dividing $$d$$ with that of the insulating material ($$D$$). In case of varying $$l$$, a minimum voltage drop was l/$$D$$ of 0.5.

Journal Articles

Pressure resistance thickness of disposal containers for spent fuel direct disposal

Sugita, Yutaka; Taniguchi, Naoki; Makino, Hitoshi; Kanamaru, Shinichiro*; Okumura, Taisei*

Nihon Genshiryoku Gakkai Wabun Rombunshi, 19(3), p.121 - 135, 2020/09

A series of structural analysis of disposal containers for direct disposal of spent fuel was carried out to provide preliminary estimates of the required pressure resistance thickness of the disposal container. Disposal containers were designed to contain either 2, 3 or 4 spent fuel assemblies in linear, triangular or square arrangements, respectively. The required pressure resistance thickness was evaluated using separation distance of the housing space for each spent fuel assembly as a key model parameter to obtain the required thickness of the body and then the lid of the disposal container. This work also provides additional analytical technical knowledge, such as the validity of the setting of the stress evaluation line and the effect of the model length on the analysis. These can then be referred to and used again in the future as a basis for conducting similar evaluations under different conditions or proceeding with more detailed evaluations.

Journal Articles

Visualization in response analyses for a nuclear power plant

Nakajima, Norihiro; Nishida, Akemi; Miyamura, Hiroko; Iigaki, Kazuhiko; Sawa, Kazuhiro

Kashika Joho Gakkai-Shi (USB Flash Drive), 36(Suppl.2), 4 Pages, 2016/10

Since nuclear power plants have dimensions approximately 100m$$^{3}$$ and their structures are an assembly made up of over 10 million components, it is not convenient to experimentally analyze its behavior under strong loads of earthquakes, due to the complexity and hugeness of plants. The proposed system performs numerical simulations to evaluate the behaviors of an assembly like a nuclear facility. The paper discusses how to carry out visual analysis for assembly such as nuclear power plants. In a result discussion, a numerical experiment was carried out with a numerical model of High Temperature engineering Test Reactor of Japan Atomic Energy Agency and its result was compared with observed data. A good corresponding among them was obtained as a structural analysis of an assembly by using visualization. As a conclusion, a visual analytics methodology for assembly is discussed.

Journal Articles

Numerical modeling assistance system in finite element analysis for the structure of an assembly

Nakajima, Norihiro; Nishida, Akemi; Kawakami, Yoshiaki; Suzuki, Yoshio; Sawa, Kazuhiro; Iigaki, Kazuhiko

Proceedings of 23rd International Conference on Nuclear Engineering (ICONE-23) (DVD-ROM), 5 Pages, 2015/05

A numerical analysis controlling and managing system is implemented on K, which controls the modelling process and data treating, although the manager only controls a structural analysis by finite element method. The modeling process is described by the list of function ID and its procedures in a data base. The manager executes the process by order in the list for simulation procedures. The manager controls the intention of an analysis by changing the analytical process one to another. Experiments were carried out with static and dynamic analyses.

Journal Articles

Numerical investigation into the linear dependence problem of partition of unity based generalized finite element methods

Tian, R.; Nakajima, Norihiro; Yagawa, Genki

Keisan Kogaku Koenkai Rombunshu, 10(1), p.393 - 396, 2005/05

A known problem of partition of unity-based generalized finite element methods (referred to as GFEM) is the linear dependence problem, which leads to singular global (stiffness) matrices. Thus far, attempts to eliminate the linear dependence problem have been unsuccessful. Numerical experiments are carried out among several GFEMs to investigate the problem. Based on the numerical experiments, simple but effective approaches to eliminating the linear dependence problem are suggested.

Journal Articles

Improved direct bonding method of Nd:YVO$$_{4}$$ and YVO$$_{4}$$ laser crystals

Sugiyama, Akira; Nara, Yasunaga

Ceramics International, 31(8), p.1085 - 1090, 2005/00

 Times Cited Count:16 Percentile:78.37(Materials Science, Ceramics)

We succeeded in the fabrication of bonded laser crystals composed of a neodymium-doped YVO$$_{4}$$ laser crystal (Nd:YVO$$_{4}$$) and its host crystals YVO$$_{4}$$ by a newly developed dry etching technique using an argon ion beam. The optical distortion caused by the bonded interface of size 5 mm $$times$$ 6 mm was estimated to be 0.05-wave at 633 nm. From the comparison of laser performance pumped by a laser diode, the bonded crystals could increase the laser output power by nearly twice that of the non-bonded crystals with the same degree of polarization of 99.2 %. To analyze the mechanism of the enhanced reduction of the thermal load in the bonded crystals, numerical simulations with a finite-element method were also performed.

JAEA Reports

Development of capsule design support subprograms for 3-dimensional temperature calculation using FEM code NISA

Tobita, Masahiro*; Matsui, Yoshinori

JAERI-Tech 2003-042, 132 Pages, 2003/03

JAERI-Tech-2003-042.pdf:7.19MB

Prediction of irradiation temperature is one of the important issues in the design of the capsule for irradiation test. Many kinds of capsules with complex structure have been designed for recent irradiation requests, and three-dimensional (3D) temperature calculation becomes inevitable for the evaluation of irradiation temperature. For such 3D calculation, however, many works are usually needed for input data preparation, and a lot of time and resources are necessary for parametric studies in the design. To improve such situation, JAERI introduced 3D-FEM (finite element method) code NISA (Numerically Integrated elements for System Analysis) and developed several subprograms, which enabled to support input preparation works in the capsule design. The 3D temperature calculation of the capsule are able to carried out in much easier way by the help of the subprograms, and specific features in the irradiation tests such as non-uniform gamma heating in the capsule, becomes to be considered.

Journal Articles

Highly thermal conductive sintered SiC fiber-reinforced 3D SiC/SiC composites; Experiments and finite-element analysis of the thermal diffusivity/conductivity

Yamada, Reiji; Igawa, Naoki; Taguchi, Tomitsugu; Jitsukawa, Shiro

Journal of Nuclear Materials, 307-311(Part2), p.1215 - 1220, 2002/12

 Times Cited Count:20 Percentile:77.82(Materials Science, Multidisciplinary)

SiC fiber-reinforced SiC composites (SiC/SiC) are considered an advanced structural material for blanket modules of a fusion reactor, which requires high thermal conductivity in order to keep thermal stresses in the material lower than the allowable design stress. The sintered SiC fiber recently developed has obtained high thermal conductivity, so it is highly expected that sintered SiC fiber-reinforced SiC/SiC composites would also show high thermal conductivity. In this study several types of 3D SiC/SiC composites were fabricated by either CVI or PIP method. The results of the thermal conductivity measurements show that the maximum thermal conductivity at room temperature was about 60 W/mK for CVI composites or 25W/mK for PIP ones. These values are considerably higher than those of non-sintered SiC fiber reinforced SiC/SiC composites, which indicates a possibility that the developed materials would be promising. The FEM thremal analysis shows the good agreement between the caluculated and experimental results.

JAEA Reports

Temperature evaluation of irradiation specimens in the HTTR for innovative basic research

Ishihara, Masahiro; Baba, Shinichi; Takahashi, Tsuneo*; Aihara, Jun; Shibata, Taiju; Hoshiya, Taiji

JAERI-Tech 2002-054, 169 Pages, 2002/07

JAERI-Tech-2002-054.pdf:5.93MB

no abstracts in English

Journal Articles

Identification of material constants in constitutive equation by indentation test with different indenters

Wakui, Takashi*; Futakawa, Masatoshi; Tanabe, Yuji*; Ioka, Ikuo

Zairyo, 51(6), p.681 - 687, 2002/06

This paper describes the novel technique for determining constants in constitutive equaution of elastic-palstic materials by the indentation test with indenters having different tip angles. FEM analyses were carried out to evaluate the effect of material constants and the indenter tip angle on the load-depth curve. The constitutive equation was determeined from the characterized curves associated with the effects on the slope. Simiulation analyses were performed for some material models to exammine accuracy of the presented technique. It is confirmed that this technique is useful to determine the constitutive equation of sub-surface of materials or coatings.

Journal Articles

Development of 3-dimensional capsule temperature calculation program using FEM (NISA Code)

Tobita, Masahiro*; Matsui, Yoshinori

KAERI/GP-195/2002, p.87 - 95, 2002/00

In the Japan Materials Testing Reactor (JMTR) of Japan Atomic Energy Research Institute (JAERI), the temperature distribution inside of irradiation specimens and capsules structure material are evaluated in the design of irradiation capsules. For the evaluation of detailed temperature distribution, NISA (Numerically Integrated elements for System Analysis) code has been introduced, and subprograms are developed to simplify the input data of the capsules structure and the analysis conditions using the three-dimensional finite element method. By the development of subprograms, prediction of the temperature distribution inside of irradiation specimens and capsules structure material became detailed and more accurate than calculation by one-dimensional code. Also estimation of detail temperature distribution during irradiation became possible based on the indication of thermocouple.

Journal Articles

Study on spallation thermal shock for mercury target vessel

Kikuchi, Kenji; Futakawa, Masatoshi; Ishikura, Shuichi*; Kogawa, Hiroyuki

Nihon Kikai Gakkai Zairyo Rikigaku Bumon Koenkai (M&M'99) Koen Rombunshu, p.467 - 468, 1999/10

no abstracts in English

Journal Articles

Radiation damage on ceramics composites as structural materials

Ishihara, Masahiro; Baba, Shinichi; Aihara, Jun; Hayashi, Kimio; Arai, Taketoshi; Ishino, Shiori*

Proceedings of 1st Information Exchange Meeting on Basic Studies on High-Temperature Engineering, p.299 - 308, 1999/09

no abstracts in English

Journal Articles

A New eigenvalue problem associated with the two-dimensional Newcomb equation without continuous spectra

Tokuda, Shinji; *

Physics of Plasmas, 6(8), p.3012 - 3026, 1999/08

 Times Cited Count:55 Percentile:84.33(Physics, Fluids & Plasmas)

no abstracts in English

Journal Articles

Performance evaluation of JAERI parallel numerical subroutine libraries using large scale structural analysis calculation

*; Kaji, Yoshiyuki; *; ; *; Kaburaki, Hideo

Keisan Kogaku Koenkai Rombunshu, 3(1), p.59 - 62, 1998/05

no abstracts in English

Journal Articles

Eigenvalue method for the outer-region matching data in resistive MHD stability analysis

Tokuda, Shinji; *

Purazuma, Kaku Yugo Gakkai-Shi, 73(10), p.1141 - 1154, 1997/10

no abstracts in English

JAEA Reports

Journal Articles

A double finite element method with accurate reflective boundary condition treatment for three-dimensional transport

Fujimura, Toichiro

Computer Physics Communications, 82, p.111 - 119, 1994/00

 Times Cited Count:1 Percentile:22.12(Computer Science, Interdisciplinary Applications)

no abstracts in English

JAEA Reports

Numerical experiment on finite element method for matching data

Tokuda, Shinji; *; *

JAERI-M 93-075, 32 Pages, 1993/03

JAERI-M-93-075.pdf:0.91MB

no abstracts in English

JAEA Reports

EDDYMULT; A Computer system for solving eddy current problems in a multi-torus system

Nakamura, Yukiharu; Ozeki, Takahisa

JAERI 1317, 310 Pages, 1989/03

JAERI-1317.pdf:7.94MB

no abstracts in English

45 (Records 1-20 displayed on this page)