The Experts below are selected from a list of 6702 Experts worldwide ranked by ideXlab platform
Atsushi Sakon - One of the best experts on this subject based on the ideXlab platform.
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first Nuclear Transmutation of 237np and 241am by accelerator driven system at kyoto university critical assembly
Journal of Nuclear Science and Technology, 2019Co-Authors: Cheol Ho Pyeon, Masao Yamanaka, Akito Oizumi, Masahiro Fukushima, Go Chiba, Kenichi Watanabe, Tomohiro Endo, Wilfred Van Rooijen, Kengo Hashimoto, Atsushi SakonAbstract:This study demonstrates, for the first time, the principle of Nuclear Transmutation of minor actinide (MA) by the accelerator-driven system (ADS) through the injection of high-energy neutrons into ...
Cheol Ho Pyeon - One of the best experts on this subject based on the ideXlab platform.
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Nuclear Transmutation of minor actinide
2021Co-Authors: Cheol Ho PyeonAbstract:Integral experiments on critical irradiation of neuptium-237 (237Np) and americium-241 (241Am) foils are carried out in a hard spectrum core at KUCA with the use of the back-to-back fission chamber, and Monte Carlo calculations together with a reference Nuclear data library are conducted for confirming the precision of numerical simulations. Subcritical irradiation of minor actinide (MA) by ADS is a very important step, before operating actual ADS facilities, in a critical assembly at zero power, such as KUCA, which is an exclusive facility for ADS that comprises a uranium-235 (235U) fueled core and a 100 MeV proton accelerator. The first significant attempt is made to demonstrate the principle of Nuclear Transmutation of MA by ADS through the injection of high-energy neutrons into the KUCA core at a subcritical state. Here, the main targets of Nuclear Transmutation of MA by the ADS experiments are fission reactions of 237Np and 241Am, and capture reactions of 237Np.
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first Nuclear Transmutation of 237np and 241am by accelerator driven system at kyoto university critical assembly
Journal of Nuclear Science and Technology, 2019Co-Authors: Cheol Ho Pyeon, Masao Yamanaka, Akito Oizumi, Masahiro Fukushima, Go Chiba, Kenichi Watanabe, Tomohiro Endo, Wilfred Van Rooijen, Kengo Hashimoto, Atsushi SakonAbstract:This study demonstrates, for the first time, the principle of Nuclear Transmutation of minor actinide (MA) by the accelerator-driven system (ADS) through the injection of high-energy neutrons into ...
Paul Erhart - One of the best experts on this subject based on the ideXlab platform.
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the role of interstitial binding in radiation induced segregation in w re alloys
Journal of Applied Physics, 2016Co-Authors: Leili Gharaee, Jaime Marian, Paul ErhartAbstract:Due to their high strength and advantageous high-temperature properties, tungsten-based alloys are being considered as plasma-facing candidate materials in fusion devices. Under neutron irradiation, rhenium, which is produced by Nuclear Transmutation, has been found to precipitate in elongated precipitates forming thermodynamic intermetallic phases at concentrations well below the solubility limit. Recent measurements have shown that Re precipitation can lead to substantial hardening, which may have a detrimental effect on the fracture toughness of W alloys. This puzzle of sub-solubility precipitation points to the role played by irradiation induced defects, specifically mixed solute-W interstitials. Here, using first-principles calculations based on density functional theory, we study the energetics of mixed interstitial defects in W-Re, W-V, and W-Ti alloys, as well as the heat of mixing for each substitutional solute. We find that mixed interstitials in all systems are strongly attracted to each other with binding energies of −2.4 to −3.2 eV and form interstitial pairs that are aligned along parallel first-neighbor 〈111〉 strings. Low barriers for defect translation and rotation enable defect agglomeration and alignment even at moderate temperatures. We propose that these elongated agglomerates of mixed-interstitials may act as precursors for the formation of needle-shaped intermetallic precipitates. This interstitial-based mechanism is not limited to radiation induced segregation and precipitation in W–Re alloys but is also applicable to other body-centered cubic alloys.
Eun Je Lee - One of the best experts on this subject based on the ideXlab platform.
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hydrophilicity improvement of polymer surfaces induced by simultaneous Nuclear Transmutation and oxidation effects using high energy and low fluence helium ion beam irradiation
Polymers, 2020Co-Authors: Jung Woo Kim, Seung Hwa Yoo, Young Bae Kong, Sung Oh Cho, Eun Je LeeAbstract:Two commodity polymers, polystyrene (PS) and high-density polyethylene (HDPE), were irradiated by high-energy He ion beams at low fluence to examine the wettability changes at different fluences. The water contact angles of the PS and HDPE surfaces were reduced from 78.3° to 46.7° and 81.5° to 58.5°, respectively, upon increasing the fluence from 0 to 1 × 1013 He2+/cm2 for irradiation durations ≤4 min. Surface analyses were performed to investigate these wettability changes. Surface texture evaluations via scanning electron and atomic force microscopies indicated non-remarkable changes by irradiation. However, the chemical structures of the irradiated polymer surfaces were notable. The high-energy He ions induced Nuclear Transmutation of C to N, leading to C–N bond formation in the polymer chains. Further, C–O and C=O bonds were formed during irradiation in air because of polymer oxidation. Finally, amide and ester groups were generated by irradiation. These polar groups improved hydrophilicity by increasing surface energies. Experiments with other polymers can further elucidate the correlation between polymer structure and surface wettability changes due to high-energy low-fluence He ion irradiation. This method can realize simple and effective utilization of commercial cyclotrons to tailor polymer surfaces without compromising surface texture and mechanical integrity.
Leili Gharaee - One of the best experts on this subject based on the ideXlab platform.
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the role of interstitial binding in radiation induced segregation in w re alloys
Journal of Applied Physics, 2016Co-Authors: Leili Gharaee, Jaime Marian, Paul ErhartAbstract:Due to their high strength and advantageous high-temperature properties, tungsten-based alloys are being considered as plasma-facing candidate materials in fusion devices. Under neutron irradiation, rhenium, which is produced by Nuclear Transmutation, has been found to precipitate in elongated precipitates forming thermodynamic intermetallic phases at concentrations well below the solubility limit. Recent measurements have shown that Re precipitation can lead to substantial hardening, which may have a detrimental effect on the fracture toughness of W alloys. This puzzle of sub-solubility precipitation points to the role played by irradiation induced defects, specifically mixed solute-W interstitials. Here, using first-principles calculations based on density functional theory, we study the energetics of mixed interstitial defects in W-Re, W-V, and W-Ti alloys, as well as the heat of mixing for each substitutional solute. We find that mixed interstitials in all systems are strongly attracted to each other with binding energies of −2.4 to −3.2 eV and form interstitial pairs that are aligned along parallel first-neighbor 〈111〉 strings. Low barriers for defect translation and rotation enable defect agglomeration and alignment even at moderate temperatures. We propose that these elongated agglomerates of mixed-interstitials may act as precursors for the formation of needle-shaped intermetallic precipitates. This interstitial-based mechanism is not limited to radiation induced segregation and precipitation in W–Re alloys but is also applicable to other body-centered cubic alloys.
