17 research outputs found

    核融合科学研究所 核融合工学研究プロジェクト 全体報告書

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    On the basis of the outstanding progress in high-density and high-temperature plasma experiments in the Large Helical Device (LHD) at National Institute for Fusion Science (NIFS), the conceptual design studies on the LHD-type helical fusion reactor, the FFHR series, have been conducted since 1993. In order to strongly promote this research activity in parallel with the acceleration of the related technological R&D for reactor components, the Fusion Engineering Research Project (FERP) was launched at NIFS in FY2010. The FERP consists of 13 tasks and 44 sub-tasks, each strongly assisted by domestic and international collaborations. The reactor design studies have focused on FFHR-d1, the demo-class reactor having a major radius of 15.6 m, which is four times larger than that of LHD. The similar heliotron magnetic configuration is employed to ensure steady-state operation with 3 GW self-ignited fusion power generation. The design activity has proceeded with the staged program, named “round,” that defines iterative working. The first round is to determine the basic core plasma parameters, the second is to compose all of the three-dimensional designs, the third focuses on construction and maintenance schemes, and the fourth is dedicated to passive safety. Since 2015, a multi-path strategy has been taken to include various options in the design, with FFHR-d1A as the base option. As a remarkable achievement of the reactor design, the Direct Profile Extrapolation (DPE) method is included in the helical systems code, HELIOSCOPE, in order to predict the confinement capability. The radial-build was successfully fixed and the neutronics calculation was carried out for the determined three-dimensional structure. The cost evaluation is also being conducted using these outcomes. The related R&D works in FERP are categorized into five key subjects: (1) large-scale superconducting (SC) magnet, (2) long-life liquid blanket, (3) low-activation structural materials, (4) high heat & particle-flux control, and (5) tritium and safety. Using the remarkable achievements of the related R&D works, the engineering design of FFHR-d1 defines the basic option and challenging option. While the basic option is an extension of the ITER technology, the challenging option includes innovative ideas from the following three purposes: (1) to overcome the difficulties related with the construction and maintenance of three-dimensionally complicated large structures, (2) to enhance the passive safety, and (3) to improve plant efficiency. For the superconducting magnet, the high-temperature superconductor (HTS) using ReBCO tapes is considered as an alternative (challenging) option to the cable-in-conduit conductor using low-temperature superconducting Nb3Sn strands. One of the purposes for selecting the HTS is to facilitate the three-dimensional winding of the helical coils by connecting prefabricated segmented conductors. A mechanical lap joint technique with low joint resistance has been developed and a 3 m-long short-sample conductor has successfully achieved 100 kA- current at a magnetic field of 5 T and temperature of 20 K. Further tests will be carried out in the world-largest 13 T, 700-mm bore superconducting magnet facility. For the tritium breeding blanket, we have chosen, as a challenging option, the liquid blanket with molten salt FLiNaBe from the viewpoint of passive safety. To increase the hydrogen solubility, an innovative idea to include powders of titanium was also proposed. An increase of hydrogen solubility over five orders of magnitude has been confirmed in an experiment, which makes the tritium permeation barrier less necessary for the coating on the walls of cooling pipes. The “Oroshhi-2” testing facility was constructed as a platform for international collaborations, having a twin-loop for testing both molten-salt (FLiNaK) and liquid metal (LiPb) under the perpendicular magnetic field of 3 T, the world’s largest for this purpose. For the structural material of blankets, a dissimilar bonding technique has been developed to join the vanadium alloy, NIFS-HEAT2, and a nickel alloy. For the helical built-in divertor, the diverter tiles could be placed at the backside of the blankets where the incident neutron flux is sufficiently reduced by an order of magnitude. It is thus expected that a copper-alloy could be used for cooling pipes under the bonded tungsten tile, since the maximum neutron fluence is limited to be lower than the allowable limit of ~1 dpa for copper within the operation period. We note that the peak heat flux on the helical divertor is expected to reach or exceed ~20 MW/m² because of the non-uniform strike point distributions, and effective removal of this heat flux is a concern. The maintenance scheme for the full-helical divertor is also a critical issue. To solve these problems, a new concept of liquid divertor has been proposed as a unique idea. Ten units of molten-tin shower jets (falls) are proposed to be installed on the inboard side of the torus to intersect the ergodic layer. It is considered that the vertical flow of tin jets could be stabilized using an internal flow resistance such as wires, chains, and tapes imbedded. In case the liquid divertor actually works, the full-helical divertor would become less necessary, though it should still be situated at the rear. Neutral particles are expected to be efficiently evacuated through the gaps between liquid metal showers. The mission of the NIFS FERP is to establish the scientific and technological basis that demonstrates the engineering feasibility of the helical fusion reactor and to promote the entire fusion engineering research toward the realization of fusion reactors in the mid-21st century. The progress of the NIFS FERP during the second six-year mid-term period in Japan for FY2010-2015 is overviewed in this full report. The numerical targets for the major components, which are the SC magnet, the in-vessel components, and the blanket, were compiled in FY2016,and its summary is also added in this report.research repor

    Electron Beam Irradiation Test Facility for Research and Development of PlasmaFacing Components

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    To develop a reliable divertor plate for large helical device(LHD), a test facility called ACT(Active Cooling Teststand) has been constructed in Toki site. The facility can generate 100 kW electron beams with beam energy of 30keV as a heat source, which can irradiate with a heat flux of up to 100 MW/m^2 to a test sample piece steadily. The beam irradiation area on the sample can be changed from 1 to 400 cm^2 with a 64 step controller electrically By using the ACT, the thermal fatigue tests of various kinds of carbon-copper brazed components are being performed under the heat loads of 2.5-14 MW/m^2. The test results show that several brazed components are applicable as the divertor plates for the first stage of LHD operation, namely with maximum heat load of 10 MW/m^2 for 5 seconds discharge durations.research repor

    Double-stranded RNA-activated protein kinase PKR of fishes and amphibians: Varying the number of double-stranded RNA binding domains and lineage-specific duplications-6

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    Xes denote exons of ORFs. Exonic parts encoding dsRBDs (dark blue), Z-DNA binding domains (Zα; light blue), kinase domains (red) and KIs (yellow) are colored. Exons are drawn to scale. Lengths (in bp) of exonic parts contributing to the ORFs are shown below the exons. Lengths (in bp) of introns are shown in between exons. Question marks indicate intron sizes of unknown length.<p><b>Copyright information:</b></p><p>Taken from "Double-stranded RNA-activated protein kinase PKR of fishes and amphibians: Varying the number of double-stranded RNA binding domains and lineage-specific duplications"</p><p>http://www.biomedcentral.com/1741-7007/6/12</p><p>BMC Biology 2008;6():12-12.</p><p>Published online 3 Mar 2008</p><p>PMCID:PMC2291453.</p><p></p

    Double-stranded RNA-activated protein kinase PKR of fishes and amphibians: Varying the number of double-stranded RNA binding domains and lineage-specific duplications-4

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    Ches. Both analyses resulted in the same tree topology. Significant bootstrap values above 70 (for maximum likelihood analysis) and significant posterior probabilities converted to percentages above 95 (for Bayesian analysis) are shown above and below the branches, respectively. Asterisks denote evident duplication events. Human and zebrafish PERK were used as outgroups for rooting the phylogenetic tree. The following abbreviations were used: Bt, (cattle); Ss, (pig); Cf, (dog); Oc, (European rabbit); Ec, (horse); Mam, (Rhesus macaque); Cae, (African green monkey); Pt, (chimpanzee); Hs, (human); Mm, (house mouse); Rn, (Norway rat); Ma, (golden hamster); Oa, (platypus); Md, (gray short-tailed opossum); Gg, (chicken); Xt, (western clawed frog); Xl, (African clawed frog); Tn, (green spotted pufferfish); Tr, (torafugu); Ga, (three spined stickleback); Ol, (Japanese medaka); Dr, (zebrafish); Pp, (fathead minnow); Ca, (goldfish); Ssa, (Atlantic salmon).<p><b>Copyright information:</b></p><p>Taken from "Double-stranded RNA-activated protein kinase PKR of fishes and amphibians: Varying the number of double-stranded RNA binding domains and lineage-specific duplications"</p><p>http://www.biomedcentral.com/1741-7007/6/12</p><p>BMC Biology 2008;6():12-12.</p><p>Published online 3 Mar 2008</p><p>PMCID:PMC2291453.</p><p></p

    Double-stranded RNA-activated protein kinase PKR of fishes and amphibians: Varying the number of double-stranded RNA binding domains and lineage-specific duplications-8

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    Shows the results of 3' RACE PCR using four different forward primers used in primary and nested PCRs for PKR1 (lanes 1–4) and three different forward primers combinations for PKR2 and PKR3 (lanes 5–7). The smaller fragment represents PKR2 and the larger one represents PKR3. (C) PCR products are shown using primers covering the complete open reading frames of PKR1 (lane 1), PKR2 (lane 2) and PKR3 (lane 3). (D) PCR reactions of overlapping regions were performed with genomic DNA to elucidate the genomic organization of PKR1. Lanes 1 and 2 show the PCR products obtained with primers spanning the region between the 5' untranslated region of PKR1 and exon 15 and exon 14 and the 3' untranslated region of exon 19, respectively. PCR product shown in lane 3 was obtained with primers covering exon 17 of PKR1 and exon 7 of PKR2. PCR products were cloned and completely sequenced.<p><b>Copyright information:</b></p><p>Taken from "Double-stranded RNA-activated protein kinase PKR of fishes and amphibians: Varying the number of double-stranded RNA binding domains and lineage-specific duplications"</p><p>http://www.biomedcentral.com/1741-7007/6/12</p><p>BMC Biology 2008;6():12-12.</p><p>Published online 3 Mar 2008</p><p>PMCID:PMC2291453.</p><p></p

    Double-stranded RNA-activated protein kinase PKR of fishes and amphibians: Varying the number of double-stranded RNA binding domains and lineage-specific duplications-3

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    approximate sizes of intergenic regions are indicated.<p><b>Copyright information:</b></p><p>Taken from "Double-stranded RNA-activated protein kinase PKR of fishes and amphibians: Varying the number of double-stranded RNA binding domains and lineage-specific duplications"</p><p>http://www.biomedcentral.com/1741-7007/6/12</p><p>BMC Biology 2008;6():12-12.</p><p>Published online 3 Mar 2008</p><p>PMCID:PMC2291453.</p><p></p

    Double-stranded RNA-activated protein kinase PKR of fishes and amphibians: Varying the number of double-stranded RNA binding domains and lineage-specific duplications-1

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    (dsR), dark blue; Z-DNA binding domains (Zα), light blue; kinase domains (KD), red; kinase inserts (KI), yellow. Total length of deduced open reading frames in amino acids (aa) is indicated above the schematics.<p><b>Copyright information:</b></p><p>Taken from "Double-stranded RNA-activated protein kinase PKR of fishes and amphibians: Varying the number of double-stranded RNA binding domains and lineage-specific duplications"</p><p>http://www.biomedcentral.com/1741-7007/6/12</p><p>BMC Biology 2008;6():12-12.</p><p>Published online 3 Mar 2008</p><p>PMCID:PMC2291453.</p><p></p

    Double-stranded RNA-activated protein kinase PKR of fishes and amphibians: Varying the number of double-stranded RNA binding domains and lineage-specific duplications-2

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    The latter of which is constitutively expressed and served as control (lower panel). Zebrafish were either treated with poly(I:C) (indicated by plus) or with PBS (minus).<p><b>Copyright information:</b></p><p>Taken from "Double-stranded RNA-activated protein kinase PKR of fishes and amphibians: Varying the number of double-stranded RNA binding domains and lineage-specific duplications"</p><p>http://www.biomedcentral.com/1741-7007/6/12</p><p>BMC Biology 2008;6():12-12.</p><p>Published online 3 Mar 2008</p><p>PMCID:PMC2291453.</p><p></p
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