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JAEA Reports

Survey of radiation protection creiteria following the accident at the Fukushima Dai-ichi Nuclear Power Plant

Yamada, Katsunori; Fujii, Katsutoshi; Kanda, Hiroshi; Higashi, Daisuke; Kobayashi, Toshiaki; Nakagawa, Masahiro; Fukami, Tomoyo; Yoshida, Keisuke; Ueno, Yumi; Nakajima, Junya; et al.

JAEA-Review 2013-033, 51 Pages, 2013/12

JAEA-Review-2013-033.pdf:2.73MB

After the accident at Fukushima Dai-ichi Nuclear Power Plant, various numerical criteria relevant to radiation protection were defined. We surveyed these criteria through internet. As a result of survey, the following 13 items were identified: (1) criteria for taking stable iodine tablets, (2) criteria for the screening of surface contamination, (3) evacuation area, sheltering area, etc., (4) activity concentrations in food, drinking water, etc., (5) dose limit for radiation workers engaged in emergency work, (6) guideline levels of radioactive substances in bathing areas, (7) criteria for use of school buildings and schoolyards, (8) restriction on planting rice, (9) acceptable activity concentrations in feedstuff, (10) acceptable activity concentrations in compost, (11) criteria for export containers and ships, (12) criteria for contaminated waste, (13) standards for radiation workers engaged in decontamination work. In this report, the basis of and issues on these criteria are summarized.

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

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

 Times Cited Count:2 Percentile:63.75

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

Development of structures for ITER toroidal field coil in Japan

Iguchi, Masahide; Chida, Yutaka; Takano, Katsutoshi; Kawano, Katsumi; Saito, Toru; Nakajima, Hideo; Koizumi, Norikiyo; Minemura, Toshiyuki*; Ogata, Hiroshige*; Ogawa, Tsuyoshi*; et al.

IEEE Transactions on Applied Superconductivity, 22(3), p.4203305_1 - 4203305_5, 2012/06

 Times Cited Count:9 Percentile:47.66(Engineering, Electrical & Electronic)

Japan Atomic Energy Agency (JAEA) has responsibility to procure 19 structures for ITER toroidal field (TF) coils as in-kind components. JAEA plans to use 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) in 2008. Large forged products were produced and their mechanical properties at 4K were evaluated. In addition, the following activities have been performed; (1) to optimize the design of each weld type identified in the manufacturing sequence, (2) to qualify typical welding procedure including repair, (3) to establish welding techniques other than narrow gap TIG welding with FMYJJ1, (4) to demonstrate the manufacturing procedures through manufacture of 1-m mockups and full-scale segments of TFC structure. This paper describes the results of material qualification and industrialization activities of manufacturing processes of ITER TFC structure.

Journal Articles

Trial fabrication of one-third scale double pancake of ITER toroidal field coil

Matsui, Kunihiro; Koizumi, Norikiyo; Hemmi, Tsutomu; Takano, Katsutoshi; Nakajima, Hideo; Kimura, Satoshi*; Iijima, Ami*; Sakai, Masahiro*; Osemochi, Koichi*; Shimada, Mamoru*

IEEE Transactions on Applied Superconductivity, 22(3), p.4203005_1 - 4203005_5, 2012/06

 Times Cited Count:6 Percentile:37.87(Engineering, Electrical & Electronic)

JAEA is responsible for the procurement of 9 toroidal field (TF) coils as Japanese Domestic Agency. JAEA had started several trials to successfully develop technologies for the TF coil manufacture since March 2009, and performed one-third scale trials aiming at qualifying and optimizing the procedures of the TF coil fabrication. The fabricated double pancakes (DPs) were successfully put into the profile with tolerances from zero to 1.5 mm. These tolerances correspond to 0.06% accuracy in the conductor length. The geometry of the DP was changed after heat treatment. Heat treatment procedure to avoid such deformation should be developed or the change of winding geometry should be taken into account in the fabrication of the TF coils. The one-third scale DP was successfully impregnated. Although exothermal reaction is given to take place during curing in the blended resin, we successfully cured the one-third scale DP.

Journal Articles

Development of ITER TF coil in Japan

Koizumi, Norikiyo; Matsui, Kunihiro; Hemmi, Tsutomu; Takano, Katsutoshi; Chida, Yutaka; Iguchi, Masahide; Nakajima, Hideo; Shimada, Mamoru*; Osemochi, Koichi*; Makino, Yoshinobu*; et al.

IEEE Transactions on Applied Superconductivity, 22(3), p.4200404_1 - 4200404_4, 2012/06

 Times Cited Count:9 Percentile:47.66(Engineering, Electrical & Electronic)

JAEA started sub- and full-scale trials to qualify and optimize manufacturing procedure of ITER TF coil from March, 2009. As major outcome of these trials, automatic winding system with accuracy in conductor length measurement of 0.01% has been established and the elongation of the conductor length due to heat treatment was measured to be 0.06%. To confirm validity of these outcomes, the authors carried out winding of a one-third scale dummy double pancake (DP), followed by its insulation and impregnation trial, and, in addition, heat treatment of one-third scale DP with real a TF conductor. The details about these trials are described in the other paper. The authors also performed trial manufacture of full scale RP and CPs for dummy double pancake, which will be made in near future. The full scale RP is manufactured by machining 10 segments in parallel to shorten machining duration and joining each segment by welding. In our trial manufacture of the full scale RP, hot-rolled SS316LN plates are machined to a final dimension, namely without additional material, and these segments are laser-welded. From these trials, manufacturing procedure of a thick hot-roll SS316LN plate is qualified and machining procedure is established, while more optimization may be necessary to achieve the required schedule and cost.

Journal Articles

Trial manufacture of ITER toroidal field coil radial plate

Takano, Katsutoshi; Koizumi, Norikiyo; Shimizu, Tatsuya; Nakajima, Hideo; Esaki, Koichi*; Nagamoto, Yoshifumi*; Makino, Yoshinobu*

Teion Kogaku, 47(3), p.178 - 185, 2012/03

In the ITER TF coil, the tight tolerances of 1 mm in flatness and a few mm in profile are required in manufacturing a radial plate (RP), although the height and width of an RP are 13 m and 9 m, respectively. In addition, since cover plates (CP) should be fitted to a groove of an RP with tolerance of 0.5 mm, the tight tolerances are also required to a CP. Thus, we can conclude that the manufacturing procedure of the RP and CP has been demonstrated.

Journal Articles

Validation of welding technology for ITER TF coil structures

Chida, Yutaka; Iguchi, Masahide; Takano, Katsutoshi; Nakajima, Hideo; Osemochi, Koichi*; Niimi, Kenichiro*; Tokai, Daisuke*; Gallix, R.*

Fusion Engineering and Design, 86(12), p.2900 - 2903, 2011/12

 Times Cited Count:10 Percentile:61.04(Nuclear Science & Technology)

TF coil structures, which support large electromagnetic force generated in TF coils under the cryogenic temperature (about 4K), are the mega welding structures composed of coil case and support structures made of high strength and high toughness stainless steel. JAEA started the study on welding trials for heavy thickness materials since 2008 and is planning of full scale mock-up model fabrication for main sub-components (1 set of inboard side and 1set of outboard side) in 2010 in order to investigate the technical issues for manufacturing of TF coil structures. This paper introduces the results on welding trials and status of full scale mock-up model fabrication to confirm the validity of welding technology and manufacturing design before fabricating actual products.

Journal Articles

Progress of mock-up trials for ITER TF coil procurement in Japan

Matsui, Kunihiro; Koizumi, Norikiyo; Hemmi, Tsutomu; Takano, Katsutoshi; Nakajima, Hideo; Osemochi, Koichi*; Savary, F.*

Fusion Engineering and Design, 86(6-8), p.1531 - 1536, 2011/10

 Times Cited Count:2 Percentile:18.37(Nuclear Science & Technology)

The magnet system for ITER comprises 18 Toroidal Field (TF) Coils using Nb$$_{3}$$Sn cable-in-conduit superconductor, which operate at 4.5 K in supercritical helium. Japan Atomic Energy Agency (JAEA) is responsible for the procurement of 9 TF coils as Japanese Domestic Agency (JADA). Before launching the procurement of these coils, reduced and full-scale trials will be performed to determine and optimize the manufacturing process of a TF coil. During the manufacture of the TF coil, heat-treated superconducting cable-in-conduit conductor, whose length may vary during heat treatment, shall be inserted in the grooves of the radial plate (RP), which is part of the mechanical structure supporting the large electromagnetic forces that are of the order of 800 kN/m. The RP also enhance reliability of the electrical insulation that will be tested up to 19 kV DC and 2.5 kV AC for the winding pack to ground. Very accurate tolerances, of the order of 0.01% on the length of the RP grooves and of the wound conductor, are required to enable the insertion of the conductor. Therefore, the development of suitable manufacturing techniques for the RP and for the winding operation is essential to achieve this requirement. JAEA has contracted companies for fabrication trials of a full-scale RP and winding trials of a one-third scale double pancake to verify feasibility of the required tolerances from an industrial view point. Prior to these trials, JAEA developed a preliminary manufacturing plan and then, industry will carry out small-scale trials to demonstrate applicability of the preliminary manufacturing plan before making the reduced and full-scale trials. The small scale trials will include the cover plate welding with the laser welding, the impregnation using the acryl and metal models, and, the mechanical test and the trail bending of the TF conductor. The results of the small-scale trials and progress on the reduced and full-scale trials are presented in this paper.

Journal Articles

Procurement of Nb$$_3$$Sn superconducting conductors in ITER

Nabara, Yoshihiro; Isono, Takaaki; Nunoya, Yoshihiko; Koizumi, Norikiyo; Hamada, Kazuya; Matsui, Kunihiro; Hemmi, Tsutomu; Kawano, Katsumi; Uno, Yasuhiro*; Seki, Shuichi*; et al.

Journal of Plasma and Fusion Research SERIES, Vol.9, p.270 - 275, 2010/08

Journal Articles

Development of the ITER toroidal field coil winding pack in Japan

Koizumi, Norikiyo; Nakajima, Hideo; Matsui, Kunihiro; Hemmi, Tsutomu; Takano, Katsutoshi; Okuno, Kiyoshi; Hasegawa, Mitsuru*; Kakui, Hideo*; Senda, Ikuo*

IEEE Transactions on Applied Superconductivity, 20(3), p.385 - 388, 2010/06

 Times Cited Count:6 Percentile:39.02(Engineering, Electrical & Electronic)

JAEA, as the JADA, signed PA for 9 ITER TF coil in 2008. The WP of the TF coil consists of seven DPs and each of DPs has a RP. The conductor is inserted in a groove of a RP and CP is welded to fix the conductor. Since flatness of 2 mm is required for a RP after welding of CPs, laser welding will be used. The tight tolerance of the CP, such as 0.3 mm, is necessary. Machining of a CP from a plate is technically promising method to satisfy the required tight tolerance. However, the machining is time consuming, resulting in penalty of high cost. Therefore, the authors study the feasibility of manufacture of a CP by new method to reduce the cost. A straight CP can be fabricated by hot-rolling and cold-drawing with sufficiently high accuracy, such as $$pm$$0.1 mm. In addition, the curved CP can be obtained by bending this straight CP with the accuracy of 0.3 mm. Thus, it is concluded that the feasibility of manufacture of the straight and curved CPs with high accuracy can be demonstrated. From these results, JAEA begins trial manufacture of the proto RP and CPs from 2009.

Journal Articles

Qualification of cryogenic structural materials for the ITER toroidal field coils

Nakajima, Hideo; Takano, Katsutoshi; Tsutsumi, Fumiaki; Kawano, Katsumi; Hamada, Kazuya; Okuno, Kiyoshi

Proceedings of 2009 ASME Pressure Vessels and Piping Division Conference (PVP 2009) (CD-ROM), 9 Pages, 2009/07

The Japan Atomic Energy Agency (JAEA) has been evaluating mechanical properties of structural materials for the ITER toroidal field (TF) coils. Newly developed JJ1 forging having thickness of 400 mm, 316LN forging having thickness of 410 mm, and 316LN hot rolled plate having thickness of 200 mm were produced in mass production process to qualify the materials. The distributions of tensile properties at liquid helium temperature (4K) in products have been evaluated to qualify the materials and it has been demonstrated that these materials have good quality and uniform properties, which satisfy the ITER requirements. It is also demonstrated from the results that temperature dependence of strengths are expressed by quadratic curves developed by JAEA, which are expressed as a function of carbon and nitrogen contents and strengths at room temperature. This equation enables to perform quality control of materials at only room temperature. The results obtained from these activities also serve the basis to develop the material material section of "Codes for Fusion Facilities - Rules on Superconducting Magnet Structure (2008)" issued by the Japan Society of Mechanical Engineers (JSME) in October 2008.

Journal Articles

Installation and test programme of the ITER poloidal field conductor insert (PFCI) in the ITER test facility at JAEA Naka

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

IEEE Transactions on Applied Superconductivity, 19(3), p.1492 - 1495, 2009/06

 Times Cited Count:1 Percentile:12.12(Engineering, Electrical & Electronic)

The ITER Poloidal Field Conductor Insert (PFCI) was constructed to characterize the performance of selected cable-in-conduit NbTi conductors for the ITER Poloidal Field (PF) under relevant operating conditions. The PFCI was installed and tested inside the bore of the ITER CS model coil, which provides the background magnetic field. The PFCI is a single-layer solenoid, wound from about 50 m of a full-size ITER cable-in-conduit conductor. The winding diameter and height are about 1.5 m and 1 m, respectively. The nominal design current of the conductor is 45 kA at 6 T and 5 K. The main items in the PFCI test programme are current sharing temperature (Tcs) measurements, critical current (Ic) measurements and AC loss measurement. The key technology of the installation, the test methods and procedures, and some preliminary results of the testing campaigns are described and discussed in this paper.

Journal Articles

Development of conduits for the ITER central solenoid conductor

Hamada, Kazuya; Nakajima, Hideo; Kawano, Katsumi; Takano, Katsutoshi; Tsutsumi, Fumiaki; Okuno, Kiyoshi; Fujitsuna, Nobuyuki*; Teshima, Osamu*

Teion Kogaku, 43(6), p.244 - 251, 2008/06

Japan Atomic Energy Agency has developed JK2LB conduit for the Nb$$_{3}$$Sn conductor of the ITER Central Solenoid. Mechanical requirements for the CS conductor conduit are 0.2% yield strength of more than 900 MPa and fracture toughness K $$_{IC}$$(J) of more than 130 MPa$$sqrt{m}$$ after a compaction and aging heat treatment (650 $$^{circ}$$C, 240 hours). In the previous work, aged JK2LB conduit has shown high strength and fracture toughness enough to satisfy the requirements. As a next step, work was performed to determine specification of the JK2LB conduit taking account of cold work including compaction and winding, and to simplify its fabrication process. To simulate the cold work effect and aging, mechanical tests were performed at 4.2 K on laboratory scale (20-30kg) ingot samples. It was found that the sum of carbon and nitrogen content should be in a range from 0.11% to 0.18% to achieve the ITER mechanical requirements. To obtain a grain size of conduit as well as that of small ingot sample, applicable solution heat treatment temperature and holding time were studied. In order to simplify the billet production process, we confirmed internal metallurgical qualities of JK2LB cast ingot. Since significant segregation was not observed, we could exclude an electroslag remelting process. Based on above achievements, full size JK2LB conduits were fabricated and satisfied the ITER mechanical requirements.

Journal Articles

Development of jacketing technologies for ITER CS and TF conductor

Hamada, Kazuya; Nakajima, Hideo; Matsui, Kunihiro; Kawano, Katsumi; Takano, Katsutoshi; Tsutsumi, Fumiaki; Okuno, Kiyoshi; Teshima, Osamu*; Soejima, Koji*

AIP Conference Proceedings 986, p.76 - 83, 2008/03

The ITER Toroidal Field (TF) coil and Central Solenoid (CS) use Nb$$_{3}$$Sn cable-in-conduit conductor. Conductor fabrication process are as follows; (1) Fabrication of jacket. (2) Butt welding of jacket to make a long tube (CS: 880 m, TF: 760 m) and insertion of superconducting cable into jacket. (3) Compaction of jacket. (4) Winding for transportation. JAEA has developed jacketing technologies in the cooperation with industries. Major achievements are as follows; (1) Full scale TF and CS jackets were fabricated using low carbon SUS316LN and boron added and high manganese stainless steel (JK2LB), respectively. The jackets satisfied ITER mechanical and dimensional requirement. (2) Butt welding condition was studied to obtain good internal surface condition of welded joint. (3) Compaction machine was constructed. As results of compaction test of TF and CS jacket, compacted jacket dimensions satisfied ITER requirement. Therefore, JAEA demonstrated jacketing technologies for ITER conductor.

Journal Articles

Demonstration of full scale JJ1 and 316LN fabrication for ITER TF coil structure

Hamada, Kazuya; Nakajima, Hideo; Kawano, Katsumi; Takano, Katsutoshi; Tsutsumi, Fumiaki; Okuno, Kiyoshi

Fusion Engineering and Design, 82(5-14), p.1481 - 1486, 2007/10

 Times Cited Count:14 Percentile:72.08(Nuclear Science & Technology)

no abstracts in English

Journal Articles

Technology development for the construction of the ITER superconducting magnet system

Okuno, Kiyoshi; Nakajima, Hideo; Sugimoto, Makoto; Isono, Takaaki; Kawano, Katsumi; Koizumi, Norikiyo; Hamada, Kazuya; Nunoya, Yoshihiko; Matsui, Kunihiro; Nabara, Yoshihiro; et al.

Nuclear Fusion, 47(5), p.456 - 462, 2007/05

 Times Cited Count:8 Percentile:29.46(Physics, Fluids & Plasmas)

no abstracts in English

Journal Articles

Optimization of JK2LB chemical composition for ITER central solenoid conduit material

Hamada, Kazuya; Nakajima, Hideo; Kawano, Katsumi; Takano, Katsutoshi; Tsutsumi, Fumiaki; Okuno, Kiyoshi; Suzuki, Tomio; Fujitsuna, Nobuyuki*

Cryogenics, 47(3), p.174 - 182, 2007/03

 Times Cited Count:30 Percentile:71.89(Thermodynamics)

no abstracts in English

Journal Articles

Technology development for the construction of ITER superconducting magnet system

Okuno, Kiyoshi; Nakajima, Hideo; Sugimoto, Makoto; Isono, Takaaki; Kawano, Katsumi; Koizumi, Norikiyo; Hamada, Kazuya; Nunoya, Yoshihiko; Nabara, Yoshihiro; Kitamura, Kazunori; et al.

Proceedings of 21st IAEA Fusion Energy Conference (FEC 2006) (CD-ROM), 8 Pages, 2007/03

The ITER superconducting magnet system consists of 18 TF coils, one CS and six Poloidal Field (PF) coils. Among six PTs, Japan, EU and US will be responsible for major part of the superconducting magnets, and Japanese contribution will be the largest, including the following four areas: part of TF conductors, about half (9 out of 19) of TF coil winding packs, most of TF coil structures and part of CS conductor. Since 2004, Japan Atomic Energy Agency (JAEA) started preparation activities for procurement, including manufacturing studies to identify detailed fabrication processes and tools for critical components, such as TF coil winding and case, and manufacturing demonstrations at full scale level on Nb$$_{3}$$Sn strands and conductors and cryogenic structural materials, such as coil case segments and radial plates. Details are described in the following sections.

Journal Articles

Demonstration of JK2LB jacket fabrication for ITER central solenoid

Hamada, Kazuya; Nakajima, Hideo; Kawano, Katsumi; Takano, Katsutoshi*; Tsutsumi, Fumiaki*; Seki, Shuichi*; Okuno, Kiyoshi; Fujitsuna, Nobuyuki*; Mizoguchi, Mitsuru*

IEEE Transactions on Applied Superconductivity, 16(2), p.787 - 790, 2006/06

 Times Cited Count:6 Percentile:37.36(Engineering, Electrical & Electronic)

no abstracts in English

97 (Records 1-20 displayed on this page)