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Journal Articles

Welding joint design of ITER toroidal field coil structure under cryogenic environment

Iguchi, Masahide; Sakurai, Takeru; Nakahira, Masataka; Koizumi, Norikiyo; Nakajima, Hideo

Proceedings of 23rd International Conference on Nuclear Engineering (ICONE-23) (DVD-ROM), 6 Pages, 2015/05

Application of partial penetration welding (PPW) to ITER Toroidal Field Coil structure has been proposed because of limited accessability for weld due to complex geometry and low stress and low importance components. In order to obtain fatigue crack growth (FCG) behavior of PPW joint in cryogenic environment, Japan Atomic Energy Agency performed FCG test at 4K by using Compact Tension (CT) specimens having as-weld notch of PPW. These CT specimens were made from mockups having one of actual joint shape of PPW, double J-groove. As the result of this test, it was observed that crack propagated in weld metal having inclination from as-weld notch. Moreover it was shown that FCG rate of as-weld CT specimens had high FCG rate region in early stage of crack propagation due to residual stress distribution. In addition, application method of this FCG rate to designing of PPW joint was proposed and verified in this study.

Journal Articles

Electromagnetic gyrokinetic simulation of turbulence in torus plasmas

Ishizawa, Akihiro*; Maeyama, Shinya; Watanabe, Tomohiko*; Sugama, Hideo*; Nakajima, Noriyoshi*

Journal of Plasma Physics, 81(2), p.435810203_1 - 435810203_41, 2015/04

 Times Cited Count:15 Percentile:20.3(Physics, Fluids & Plasmas)

Journal Articles

JAEA's contribution to development of J-MOX safeguards system

Nagatani, Taketeru; Nakajima, Shinji; Kawakubo, Yoko; Shiromo, Hideo; Asano, Takashi; Marlow, J.*; Swinhoe, M. T.*; Menlove, H.*; Rael, C.*; Kawasue, Akane*; et al.

Book of Abstracts, Presentations and Papers of Symposium on International Safeguards; Linking Strategy, Implementation and People (Internet), 8 Pages, 2015/03

Journal Articles

Manufacturing technology and material properties of high nitrogen austenitic stainless steel forgings for ITER TF coil cases

Oshikawa, Takumi*; Funakoshi, Yoshihiko*; Imaoka, Hiroshi*; Yoshikawa, Kohei*; Maari, Yasutaka*; Iguchi, Masahide; Sakurai, Takeru; Nakahira, Masataka; Koizumi, Norikiyo; Nakajima, Hideo

Proceedings of 19th International Forgemasters Meeting (IFM 2014), p.254 - 259, 2014/09

ITER is a large-scale experiment that aims to demonstrate that it is possible to produce commercial energy from fusion. ITER Toroidal Field Coil Case (hereinafter referred to as "ITER TFCC") is one of the important components of ITER. The ITER TFCC materials are made of high nitrogen austenitic stainless steel and having various configurations. The ITER TFCC material which manufactured by JCFC has a complex configuration with heaver thickness than other materials. It is difficult to form near net shape to delivery configuration by ordinary open die forging method such as upset and stretching, because the ITER TFCC materials manufactured by JCFC have a complex configuration. Therefore ingot weight and lead time of machining increase when ITER TFCC materials are forged by ordinary open die forging method. Moreover, in order to get good attenuation at Ultrasonic examination, it is necessarily to make fine and uniform grain of the material. However, it is impossible to control grain size of austenitic stainless steel by heat treatment. The grain becomes fine and uniform by only forging process with suitable condition. Therefore, JCFC has studied suitable forging method to become near net shape to delivery configuration and also to get fine grain of center of the material. Based on these result, ITER TFCC materials were manufactured. This innovative forging process led to reduce the weight of ingot compared with general forging. And it had good Ultrasonic attenuation. It was confirmed that the results of material test and nondestructive examination satisfied the requirements of Japan domestic agency (hereinafter referred to as "JADA"). Moreover, the test coupons were taken from center of thick part of product and used for various tests. As the result of tests, it was confirmed that results of material test satisfied the requirements of JADA. It is clear that this innovative forging method is very suitable process for manufacturing of ITER TFCC materials.

Journal Articles

Monte Carlo N-Particle eXtended (MCNPX) simulation for passive neutron measurement of fuel debris at Fukushima Daiichi Nuclear Power Plants

Nagatani, Taketeru; Nakajima, Shinji; Kosuge, Yoshihiro*; Shiromo, Hideo; Asano, Takashi

Proceedings of INMM 55th Annual Meeting (Internet), 10 Pages, 2014/07

Meltdown of the reactor cores of Units 1-3 occurred at Fukushima Daiichi Nuclear Power Plants (1F). Fuel debris at 1F contains minor actinides and fission products and neutron absorber. These materials make it difficult to quantify fertile nuclear materials in fuel debris by the conventional passive neutron technique. We consider that DDSI and PNAR which focused on fissile material are promising techniques to quantify the nuclear materials in the fuel debris. A concept of application of these techniques to fuel debris measurement was investigated and presented at the last INMM annual meeting. In order to evaluate the applicability of these techniques to fuel debris measurement, we investigated the neutron behavior in the fuel debris by using MCNPX simulation code. Because property of fuel debris is not clear, source term data used were prepared by referring TMI data. This paper provides results of MCNPX simulation for fuel debris measurement at 1F with passive neutron techniques.

Journal Articles

Performance test results for the Advanced Fuel Assembly Assay System (AFAS) on the active length verification of LWR MOX fuel assembly by neutron detectors

Nakajima, Shinji; Nagatani, Taketeru; Shiromo, Hideo; Asano, Takashi; Marlow, J. B.*; Swinhoe, M. T.*; Menlove, H. O.*; Rael, C. D.*; Kawasue, Akane*; Iso, Shoko*; et al.

Proceedings of INMM 55th Annual Meeting (Internet), 10 Pages, 2014/07

The Advanced Fuel Assembly Assay System (AFAS) is an unattended non-destructive assay (NDA) system by neutron measurement to verify the plutonium amount in an LWR plutonium and uranium mixed oxide (MOX) fuel assembly. The assembly will be fabricated in the MOX fuel fabrication plant under construction by the Japan Nuclear Fuel Limited. The AFAS has been developed by Los Alamos National Laboratory under the auspices of the Secretariat of Nuclear Regulation Authority in Japan. The AFAS is the first NDA system which will verify the active length of the assembly without inspector attendance. Japan Atomic Energy Agency (JAEA) has conducted the performance test for the AFAS under the contract with Nuclear Material Control Center to demonstrate this active length verification technology by using MOX fuel assemblies owned by JAEA. As the results, it was confirmed that measurement error of the active length for the MOX fuel assembly was less than 0.1% and it was satisfied with requirement by IAEA. This paper provides the performance test results for the active length verification of the AFAS.

Journal Articles

Progress of manufacturing trials for the ITER toroidal field coil structures

Iguchi, Masahide; Morimoto, Masaaki; Chida, Yutaka*; Hemmi, Tsutomu; Nakajima, Hideo; Nakahira, Masataka; Koizumi, Norikiyo; Yamamoto, Akio*; Miyake, Takashi*; Sawa, Naoki*

IEEE Transactions on Applied Superconductivity, 24(3), p.3801004_1 - 3801004_4, 2014/06

 Times Cited Count:6 Percentile:54.12(Engineering, Electrical & Electronic)

no abstracts in English

Journal Articles

Electromagnetic gyrokinetic turbulence in finite-beta helical plasmas

Ishizawa, Akihiro*; Watanabe, Tomohiko*; Sugama, Hideo*; Maeyama, Shinya; Nakajima, Noriyoshi*

Physics of Plasmas, 21(5), p.055905_1 - 055905_10, 2014/05

 Times Cited Count:11 Percentile:35.79(Physics, Fluids & Plasmas)

Journal Articles

Mechanical properties of full austenitic welding joint at cryogenic temperature for the ITER toroidal field coil structure

Iguchi, Masahide; Saito, Toru; Kawano, Katsumi; Chida, Yutaka; Nakajima, Hideo; Ogawa, Tsuyoshi*; Katayama, Yoshinori*; Ogata, Hiroshige*; Minemura, Toshiyuki*; Tokai, Daisuke*; et al.

Fusion Engineering and Design, 88(9-10), p.2520 - 2524, 2013/10

 Times Cited Count:8 Percentile:33.89(Nuclear Science & Technology)

ITER TFC structures are large welding structures made of heavy thick stainless steels. JAEA plans to apply narrow gap TIG welding with FMYJJ1 which is full austenitic stainless filler material to manufacture TFC structure. FMYJJ1 is specified in "Codes for Fusion Facilities -Rules on Superconducting Magnet Structure (2008)". In order to evaluate effect of base material combinations and thickness of welded joint on tensile properties at 4 K, tensile tests were conducted at 4 K by using tensile specimens taken from 40 mm thickness weld joints of four combinations and 200 mm thickness ones of two combinations of base materials. These weld joints were manufactured by one side narrow gap TIG welding with FMYJJ1. As the results, it was confirmed that yield and tensile strengths of welded joint at 4K were decreased with decreasing of nitrogen of base material, and there were no large distribution of strengths at 4 K along the thickness of welded joints of 200 mm thickness.

Journal Articles

Cryogenic structures of superconducting coils for fusion experimental reactor "ITER"

Nakajima, Hideo; Shimamoto, Susumu*; Iguchi, Masahide; Hamada, Kazuya; Okuno, Kiyoshi; Takahashi, Yoshikazu

Teion Kogaku, 48(10), p.508 - 516, 2013/10

JAEA is procuring both structural materials and structural design of Toroidal Field (TF) coil and Central Solenoid (CS) for ITER. Although 316LN is used in the most parts of the superconducting magnets system, the cryogenic stainless steels, JJ1 and JK2LB, which were newly developed by JAEA and Japanese steel companies, are used in the highest stress area of TF coil case and whole CS conductor jackets, respectively. These two materials became commercially available based on demonstration of productivity and weldability of materials, and evaluations of 4 K mechanical properties of trial products including welded parts. In order to simplify quality control in mass production, JAEA has used materials specified in the material section of "Codes for Fusion Facilities - Rules on Superconducting Magnet Structure (2008)" issued by the Japan Society of Mechanical Engineers (JSME). The design of structural materials, production technology and quality control are described in this paper.

Journal Articles

Cable twist pitch variation in Nb$$_{3}$$Sn conductors for ITER toroidal field coils in Japan

Takahashi, Yoshikazu; Nabara, Yoshihiro; Hemmi, Tsutomu; Nunoya, Yoshihiko; Isono, Takaaki; Hamada, Kazuya; Matsui, Kunihiro; Kawano, Katsumi; Koizumi, Norikiyo; Oshikiri, Masayuki; et al.

IEEE Transactions on Applied Superconductivity, 23(3), p.4801504_1 - 4801504_4, 2013/06

 Times Cited Count:11 Percentile:39.67(Engineering, Electrical & Electronic)

Japan Atomic Energy Agency (JAEA) is the first to start the mass production of the TF conductors in March 2010 among the 6 parties who are procuring TF conductors in the ITER project. The height and width of the TF coils are 14 m and 9 m, respectively. The conductor is cable-in-conduit conductor (CICC) with a central spiral. A circular multistage superconducting cable is inserted into a circular stainless steel jacket with a thickness of 2 mm. A total of 900 Nb$$_{3}$$Sn strands and 522 copper strands are cabled around the central spiral and the cable is inserted into a round-in-round stainless steel jacket. It was observed that the cabling pitch of the destructive sample is longer than the original pitch at cabling. The JAEA carried out the tensile tests of the cable and the measurement of the cable rotation during the insertion to investigate the cause of the elongation. The cause of elongation was clarified and the results will be described in this paper.

Journal Articles

Examination of Nb$$_{3}$$Sn conductors for ITER central solenoids

Nabara, Yoshihiro; Hemmi, Tsutomu; Kajitani, Hideki; Ozeki, Hidemasa; Iguchi, Masahide; Nunoya, Yoshihiko; Isono, Takaaki; Takahashi, Yoshikazu; Matsui, Kunihiro; Koizumi, Norikiyo; et al.

IEEE Transactions on Applied Superconductivity, 23(3), p.4801604_1 - 4801604_4, 2013/06

 Times Cited Count:7 Percentile:52.9(Engineering, Electrical & Electronic)

no abstracts in English

Journal Articles

Gyrokinetic turbulence simulations of high-beta tokamak and helical plasmas with full-kinetic and hybrid models

Ishizawa, Akihiro*; Maeyama, Shinya; Watanabe, Tomohiko*; Sugama, Hideo*; Nakajima, Noriyoshi*

Nuclear Fusion, 53(5), p.053007_1 - 053007_13, 2013/05

 Times Cited Count:17 Percentile:25.81(Physics, Fluids & Plasmas)

Journal Articles

ITER magnet systems; From qualification to full scale construction

Nakajima, Hideo; Hemmi, Tsutomu; Iguchi, Masahide; Nabara, Yoshihiro; Matsui, Kunihiro; Chida, Yutaka; Kajitani, Hideki; Takano, Katsutoshi; Isono, Takaaki; Koizumi, Norikiyo; et al.

Proceedings of 24th IAEA Fusion Energy Conference (FEC 2012) (CD-ROM), 8 Pages, 2013/03

The ITER organization and 6 Domestic Agencies (DA) have been implementing the construction of ITER superconducting magnet systems. Four DAs have already started full scale construction of Toroidal Field (TF) coil conductors. The qualification of the radial plate manufacture has been completed, and JA and EU are ready for full scale construction. JA has qualified full manufacturing processes of the winding pack with a 1/3 prototype and made 2 full scale mock-ups of the basic segments of TF coil structure to optimize and industrialize the manufacturing process. Preparation and qualification of the full scale construction of the TF coil winding is underway by EU. Procurement of the manufacturing equipment is near completion and qualification of manufacturing processes has already started. The constructions of other components of the ITER magnet systems are also going well towards the main goal of the first plasma in 2020.

Journal Articles

Evolution of cryogenic structural material development for superconducting coils in fusion reactor

Shimamoto, Susumu*; Nakajima, Hideo; Takahashi, Yoshikazu

Teion Kogaku, 48(2), p.60 - 67, 2013/03

JAEA started development of cryogenic structural material for Tokomak fusion reactor 30 years ago. Because, there was no specialized steel and mechanical data at 4K, JAEA settled target of mechanical characteristics which should satisfy requirements for coil structure at 4K and equipped evaluation facilities at 4K such as tensile test, fatigue test and so on. On the other hand JAEA initiated collaboration with steel industries in order to realize new cryogenic structural material and carried out mechanical evaluation at 4K on numerous samples which were supplied from industries. JAEA contributed standardization of these testing methods at 4K specified in the Japanese industrial standards (JIS). JAEA also supported to establish a construction code for structure of superconducting coil for fusion facility at the Japan Society of Mechanical Engineer (JSME), which is used in manufacture of the ITER toroidal field coil. This paper describes history over 30 years on the material development.

Journal Articles

Turbulent transport due to kinetic ballooning modes in high-beta toroidal plasmas

Ishizawa, Akihiro*; Maeyama, Shinya; Watanabe, Tomohiko*; Sugama, Hideo*; Nakajima, Noriyoshi*

Proceedings of 24th IAEA Fusion Energy Conference (FEC 2012) (CD-ROM), 8 Pages, 2012/10

Journal Articles

Effect of specimen shape on the elongation of 316LN jacket used in the ITER toroidal field coil

Hamada, Kazuya; Kawano, Katsumi; Saito, Toru; Iguchi, Masahide; Nakajima, Hideo; Teshima, Osamu*; Matsuda, Hidemitsu*

AIP Conference Proceedings 1435, p.55 - 62, 2012/06

 Times Cited Count:3 Percentile:19.62

The TF coil conductor was composed of 900 Nb$$_{3}$$Sn superconducting strands and 522 Cu strands protected by circular sheath tube (jacket) with the outer diameter of 43.7 mm. The jacket section is a seamless tube made of modified 316LN. JAEA tested different types of tensile specimen (Japanese Industrial Standards (JIS) type and ASTM type) cut from jacket. ASTM type specimen has longer and wider reduced section than those of JIS type specimen. Elongation of as received condition is not dependent on specimen shape. But after cold work and aging, the elongation is deteriorated due to a sensitization and scattering of elongation is larger than that of as received condition. Fracture mode of aged jacket is "cup and cone fracture", which have a mixture of inter granular at center area and trans-granular factures in circumference area. It is considered that initiation of fracture is more sensitive on test specimen shape with low ductility.

Journal Articles

Estimation of tensile strengths at 4K of 316LN forging and hot rolled plate for the ITER toroidal field coils

Iguchi, Masahide; Saito, Toru; Kawano, Katsumi; Takano, Katsutoshi; Tsutsumi, Fumiaki; Chida, Yutaka; Nakajima, Hideo

AIP Conference Proceedings 1435, p.70 - 77, 2012/06

A prediction method for tensile strengths at liquid helium temperature (4K) has been developed in order to rationalize qualification tests of cryogenic structural materials used in large superconducting magnet for a fusion device. This method is to use quadratic curves which are expressed as a function of carbon and nitrogen contents and strengths at room temperature. This study shows results of tensile tests at 4K and confirmation of accuracy of prediction method for tensile strengths at 4K for large forgings and thick hot rolled plates of austenitic stainless steels, which can be used in the actual coil case and radial plates of the ITER toroidal field coils. These products are 316LN having high nitrogen from 0.09 to 0.24% and maximum thickness is 600mm. As the results, it was confirmed that the tensile strengths of these products at 4K can be predicted by using appropriate quadratic curves. And distribution of strengths for each product was estimated.

Journal Articles

Method to evaluate CIC conductor performance by voltage taps using CSMC facility

Nunoya, Yoshihiko; Nabara, Yoshihiro; Matsui, Kunihiro; Hemmi, Tsutomu; Takahashi, Yoshikazu; Isono, Takaaki; Hamada, Kazuya; Koizumi, Norikiyo; Nakajima, Hideo

IEEE Transactions on Applied Superconductivity, 22(3), p.4803804_1 - 4803804_4, 2012/06

 Times Cited Count:0 Percentile:100(Engineering, Electrical & Electronic)

no abstracts in English

Journal Articles

Mass production of Nb$$_{3}$$Sn conductors for ITER toroidal field coils in Japan

Takahashi, Yoshikazu; Isono, Takaaki; Hamada, Kazuya; Nunoya, Yoshihiko; Nabara, Yoshihiro; Matsui, Kunihiro; Hemmi, Tsutomu; Kawano, Katsumi; Koizumi, Norikiyo; Oshikiri, Masayuki; et al.

IEEE Transactions on Applied Superconductivity, 22(3), p.4801904_1 - 4801904_4, 2012/06

 Times Cited Count:7 Percentile:51.86(Engineering, Electrical & Electronic)

Japan Atomic Energy Agency is the first to start the mass production of the TF conductors in Phase IV in March 2010 among the 6 parties who are procuring TF conductors in the ITER project. The conductor is cable-in-conduit conductor with a central spiral. A total of 900 Nb$$_{3}$$Sn strands and 522 copper strands are cabled around the central spiral and then wrapped with stainless steel tape whose thickness is 0.1 mm. Approximately 60 tons of Nb$$_{3}$$Sn strands were manufactured by the two suppliers in December 2010. This amount corresponds to approximately 55% of the total contribution from Japan. Approximately 30% of the total contribution from Japan was completed as of February 2011. JAEA is manufacturing one conductor per month under a contract with two Japanese companies for strands, one company for cabling and one company for jacketing. This paper summarizes the technical developments including a high-level quality assurance. This progress is a significant step in the construction of the ITER machine.

280 (Records 1-20 displayed on this page)