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Criticality characteristics of fuel debris mixed by fuels with different burnups based on fuel loading pattern

渡邉 友章; 大久保 清志*; 荒木 祥平; 外池 幸太郎

Proceedings of 11th International Conference on Nuclear Criticality Safety (ICNC 2019) (Internet), 8 Pages, 2019/09

The fuel debris produced by the accident of the Fukushima Daiichi Nuclear Power Station (1F) is probably in a state of mixture of burned fuels with different burnups each other. In such a case, the mixing ratio of burned fuels in fuel debris would affect its criticality. This report shows computation results of criticality characteristics of fuel-debris compositions prepared by mixing nuclide compositions of burned fuels in various patterns based on a fuel loading pattern. The results indicate that fuel debris is potentially subcritical when 1-cycle fuels, whose average burnup is several GWd/t, are included homogeneously in fuel debris because remaining $$^{155}$$Gd and $$^{157}$$Gd in 1-cycle fuels works to reduce neutron multiplication. The results also indicate that $$^{155,157}$$Gd/$$^{235}$$U ratio well characterize criticality of fuel debris.


Structure of nitride layer formed on titanium alloy surface by N$$_{2}$$-gas exposure at high temperatures

武田 裕介; 飯田 清*; 佐東 信司*; 松尾 忠利*; 長嶋 泰之*; 大久保 成彰; 近藤 啓悦; 平出 哲也

JPS Conference Proceedings (Internet), 25, p.011023_1 - 011023_3, 2019/03



Structure of nitride layer formed on titanium alloy surface by N$$_{2}$$-gas exposure at high temperatures

武田 裕介; 飯田 清*; 佐東 信司*; 松尾 忠利*; 長嶋 泰之*; 大久保 成彰; 近藤 啓悦; 平出 哲也

Journal of Physics; Conference Series, 791(1), p.012022_1 - 012022_4, 2017/02

 被引用回数:1 パーセンタイル:44.02

ゴルフクラブや、航空機用構造材料等に広く用いられているチタン合金は、表面を窒化処理することで硬さを飛躍的に増すことが知られているが、熱処理温度または時間によっては表面に形成された窒化層が負荷により簡単に剥離してしまい、実用性に欠く場合がある。そこでわれわれは2つの窒化条件、(1)810$$^{circ}$$C 600minと(2) 850$$^{circ}$$C 720minで処理した試料を準備し、その表面に形成された窒化層を、陽電子消滅$$gamma$$線ドップラー広がり(DB)測定で評価した。窒素の拡散のみ考慮して評価すると0.05-0.1$$mu$$mまで窒化されると予想されるが、DBによる評価では窒化によって導入される欠陥層は0.5$$mu$$mを超える領域まで達していることがわかった。


Criticality characteristics of MCCI products possibly produced in reactors of Fukushima Daiichi Nuclear Power Station

外池 幸太郎; 大久保 清志; 高田 友幸*

Proceedings of International Conference on Nuclear Criticality Safety (ICNC 2015) (DVD-ROM), p.292 - 300, 2015/09




深谷 洋行; 須山 賢也; 薗田 暁; 大久保 清志; 梅田 幹; 内山 軍蔵

JAEA-Research 2013-020, 81 Pages, 2013/10




Mach-Zehnder polymer waveguides fabricated using proton beam writing

三浦 健太*; 佐藤 隆博; 石井 保行; 江夏 昌志; 桐生 弘武*; 小澤 優介*; 高野 勝昌*; 大久保 猛; 山崎 明義; 加田 渉; et al.

JAEA-Review 2012-046, JAEA Takasaki Annual Report 2011, P. 126, 2013/01

In this study, a PMMA-based MZ waveguide was fabricated utilizing PBW to develop a thermo-optic switch. A 10-$$mu$$m-thick PMMA film was firstly spin-coated onto the 15 $$mu$$m SiO$$_2$$ film as the under cladding. Cores of a MZ waveguide with 8 $$mu$$m width were secondary drawn at the dose of 100 nC/mm$$^2$$ in the PMMA film using PBW with H$$^+$$ beam of the size of $$sim$$1.1 $$mu$$m and beam current of $$sim$$50 pA at 1.7 MeV. The MZ waveguide was drawn by symmetrically coupling two Y junctions and its branching angle was set to 2$$^circ$$ to reduce optical branching loss. Finally a 10-$$mu$$m-thick PMMA film was deposited again on the sample as an upper cladding by spin-coating. The mode-field diameter of near field patterns with about 10 $$mu$$m width was observed at $$lambda$$= 1.55 $$mu$$m on the basis of a fundamental mode without no higher-order modes which required to develop our objective MZ type thermo-optic switch for optical-fiber telecommunication. The result of the observation showed that the PMMA-based single-mode MZ waveguide for $$lambda$$= 1.55 $$mu$$m was successfully fabricated using PBW. As the next step to develop the optical switch, we will form a Ti thin-film heater and A$$ell$$ electrodes on the MZ waveguide using photolithography and wet-etching processes.


Fabrication of Mach-Zehnder polimer waveguides by a direct-drawing technique using a focused proton beam

三浦 健太*; 佐藤 隆博; 石井 保行; 桐生 弘武*; 小澤 優介*; 江夏 昌志; 高野 勝昌*; 大久保 猛; 山崎 明義; 加田 渉; et al.

Key Engineering Materials, 534, p.158 - 161, 2013/00

 被引用回数:5 パーセンタイル:90.74

We develop a thermo-optic switch of the Mach-Zehnder type polymer waveguide using proton beam writing (PBW). In this study, we succeeded in near field pattern Mach-Zehnder type single mode polymer waveguides at a wavelength of 1550 nm. The samples for the waveguides were composed with a 15-$$mu$$-thick under-cladding layer of SiO$$_2$$ deposited on a Si substrate using radio-frequency sputtering and a 10-$$mu$$m-thick PMMA film spin-coated onto the SiO$$_2$$ layer as a core layer. We wrote Mach-Zehnder type waveguides having a width of 8 $$mu$$m on the PMMA layer by PBW with a beam size of $$sim$$1 $$mu$$m and a beam current of 50 pA. After this writing, the 10-$$mu$$m-thick-PMMA layer was deposited again as an upper-cladding layer by spin-coating. In the observation of these waveguides, the light of laser of 1550-nm wavelength was injected into one side of the waveguide through a single-mode fiber. From the observation of the light emitted from the opposite side of the waveguides, near field patterns was observed using a vidicon camera with an optical microscope. The observation result demonstrated that the light traveled by single mode in the Mach-Zehnder type polymer waveguide. In the conference, we will report the development of the Mach-Zehnder type polymer waveguide in detail. In addition, the thermo-optic switch at the wavelength of 1550 nm by the Mach-Zehnder type polymer waveguide will also be briefly reported.


Infinite multiplication factor of low-enriched UO$$_2$$-concrete system

井澤 一彦; 内田 有里子; 大久保 清志; 戸塚 真義; 曽野 浩樹; 外池 幸太郎

Journal of Nuclear Science and Technology, 49(11), p.1043 - 1047, 2012/11


 被引用回数:12 パーセンタイル:68.15(Nuclear Science & Technology)



Fabrication of Y-junction waveguides using proton beam writing

三浦 健太*; 佐藤 隆博; 石井 保行; 江夏 昌志; 上原 政人*; 桐生 弘武*; 高野 勝昌*; 大久保 猛; 山崎 明義; 加田 渉; et al.

JAEA-Review 2011-043, JAEA Takasaki Annual Report 2010, P. 126, 2012/01

We develop optical waveguides using Proton Beam Writing (PBW). In this study, Y-junction PMMA film waveguides at 1.55 $$mu$$m were fabricated using PBW. First, an SiO$$_2$$ film was deposited as an under-cladding on an Si substrate using radio-frequency sputtering. After a PMMA film was spin-coated on the SiO$$_2$$ film, the sample was baked at 120 $$^{circ}$$C. The thickness of PMMA film became 10 $$mu$$m by repeating these processes twice. Next, a Y-junction waveguides with the width of 8 $$mu$$m and branching angle of 2 $$^circ$$ were drawn in the PMMA film on the condition of the dose of 100 nC/mm$$^2$$ using PBW having a 1.7 MeV proton beam with the current of 10 pA and the size of about 1 $$mu$$m. Finally, a 10-$$mu$$m thick PMMA film was deposited again on the sample as an upper-cladding layer by spin-coating. The observation of an optical microscope showed that an objective Y-junction was successfully drawn using PBW. To observe near field patterns (NFPs), the laser light of wavelength at 1.55 $$mu$$n was injected through a single-mode fiber (SMF) from one side of the edge of the waveguide cleaved both sides of the sample. The two independent NFPs were observed form each branching waveguide using a vidicon camera at the opposite side of the waveguide. The observation result of the two NFPs with an optical power intensity ratio of 1:0.98 demonstrated that the light of 1.55 $$mu$$m was divided at almost equal ratio by this Y-junction.


Improvement of spatial resolution of PIXE-CT using ML-EM algorithm in TIARA

佐藤 隆博; 江夏 昌志; 加田 渉; 横山 彰人; 大久保 猛; 山崎 明義; 石井 保行; 神谷 富裕

JAEA-Review 2011-043, JAEA Takasaki Annual Report 2010, P. 83, 2012/01

In order to get better spatial resolution of PIXE-CT, ML-EM (maximum likelihood expectation maximization) iterative algorithm) was used instead of FBP. The ML-EM algorithm had been developed for emission computed tomography such as SPECT (single photon emission computed tomography). It is relatively easy to apply the ML-EM to micro-PIXE because both SPECT and micro-PIXE originated from photon emission phenomena. Moreover, unlike FBP, the ML-EM algorithm has highly resistance against the errors of projection images and is suitable for rare event analyses such as micro-PIXE. As a result, the estimated FWHM is 4.4 $$pm$$ 0.6 $$mu$$m, which is the best performance of PIXE-CT in our study.


The Analysis of boron micro-distribution in 9L gliosarmoma cells and HUVEC cells using PIXE and PIGE

遠藤 聖*; 柴田 靖*; 山本 哲哉*; 中井 啓*; 松村 明*; 佐藤 隆博; 横山 彰人; 江夏 昌志; 大久保 猛; 山崎 明義; et al.

JAEA-Review 2011-043, JAEA Takasaki Annual Report 2010, P. 86, 2012/01

Micro particle-induced X-ray emission (micro-PIXE) was applied to determine the inter- and intracellular distribution of boron-10 ($$^{10}$$B) in tumor cells. The peak $$^{10}$$B atom measurement was large on the measurement spectrum in comparison to the circumference background. It was possible to confirm that $$^{10}$$B atoms were measured. But, the intracellular micro-distribution of boron could not be clearly detected in this analysis. Improvements are therefore necessary in the technical methods of cell fixation, while the micro-PIXE and PIGE analyzing system also needs to be further upgraded.


Fabrication of polymer optical waveguides for the 1.5-$$mu$$m band using focused proton beam

三浦 健太*; 町田 裕貴*; 上原 政人*; 桐生 弘武*; 小澤 優介*; 佐々木 友之*; 花泉 修*; 佐藤 隆博; 石井 保行; 江夏 昌志; et al.

Key Engineering Materials, 497, p.147 - 150, 2012/00

 被引用回数:7 パーセンタイル:95.62

Proton beam writing (PBW) is an attractive technique for next-generation micro-fabrication. We study the fabrication of optical waveguides of polymer materials using PBW. In this study, the optical waveguides of photorefractive polysilane "GLASSIA" was fabricated. The samples for the waveguides were prepared as follows; (1) An under-cladding layer of SiO$$_2$$ having a thickness of $$sim$$15 $$mu$$m was deposited on a Si substrate using radio-frequency sputtering. (2) A polysilane layer having a thickness of $$sim$$10 $$mu$$m was spin-coated onto the SiO$$_2$$ layer as a core layer. Optical waveguides were drawn by scanning a 1.7 MeV focused proton beam with $$sim$$1 $$mu$$m size and beam current of 50 pA which was produced by a submicron focused ion beam system connected with the 3 MV single-ended accelerator at JAEA. The drawing was carried out on the dose of 100, 200, 300 nC/mm$$^2$$ each. After the drawing, the sample surfaces were observed using an optical microscope and AFM. The observation result showed that the refractive index was changed and the cores of the waveguides were formed. We will report the details of above observation results in the conference. The change ratio of the refraction index will also be reported on the basis of the obtained result by inserting light ($$lambda$$ = 1.55 $$mu$$m) into the waveguide structure through a single-mode fiber.


Fabrication of polymer optical waveguides for the 1.5-$$mu$$m band using focused proton beam

三浦 健太*; 町田 裕貴*; 上原 政人*; 桐生 弘武*; 小澤 優介*; 佐々木 友之*; 花泉 修*; 佐藤 隆博; 石井 保行; 江夏 昌志; et al.

Key Engineering Materials, 497, p.147 - 150, 2011/12

 被引用回数:6 パーセンタイル:2.48

Single mode straight waveguides for a wavelength of 1.55-$$mu$$m were, so far, fabricated using a proton beam writing (PBW) technique. We report the fabrication of Y-junction polymer waveguides with a polymethyl methacralate (PMMA) layers as the expansion of these straight waveguides using PBW in the conference. The PMMA layers consisted of an under-cladding layer of SiO$$_2$$ having a thickness of $$sim$$ 15-$$mu$$m deposited on an Si substrate, a PMMA layer having a thickness of $$sim$$ 10-$$mu$$m spin-coated onto the SiO$$_2$$ layer and a Y-junction waveguide with a width of 8-$$mu$$m in a PMMA core layer. The Y-junction waveguides with the angle of 2$$^{circ}$$ were drawn using the 1.7 MeV proton beam with 1-$$mu$$m in diameter and a beam current of 10 pA for a dose of 100 nC/mm$$^2$$. After spin-coating the PMMA layer with $$sim$$ 10-$$mu$$m thickness as an upper cladding on the irradiated PMMA layer, the near field pattern (NFP) of an 8-$$mu$$m-width Y-junction waveguide was observed using a tunable-wavelength laser. The observation showed that the fabrication of waveguide was succeeded because its waveguide was single mode and the intensity ratio between the two outputted lights was the almost same; 1:0.96. We also briefly report the next plans of the measurement of the refractive indices of proton-irradiated PMMA and SiO$$_2$$ films and the fabrication of a thermo-optic polymer switch based on a Mach-Zehnder interferometer waveguide.


Study on reactivity effect of fission products for introducing burnup credit into the criticality safety evaluation of spent nuclear fuel

大久保 清志*; 須山 賢也; 内山 軍蔵

Proceedings of International Conference on Toward and Over the Fukushima Daiichi Accident (GLOBAL 2011) (CD-ROM), 6 Pages, 2011/12



Re-evaluation of assay data of spent nuclear fuel obtained at Japan Atomic Energy Research Institute for validation of burnup calculation code systems

須山 賢也; 村崎 穣*; 大久保 清志; 中原 嘉則*; 内山 軍蔵

Annals of Nuclear Energy, 38(5), p.930 - 941, 2011/05

 被引用回数:13 パーセンタイル:71.09(Nuclear Science & Technology)



連続エネルギモンテカルロコードMVP及びMCNPを使用する統合化燃焼計算コードシステム; SWAT3.1

須山 賢也; 望月 弘樹*; 高田 友幸*; 龍福 進*; 奥野 浩; 村崎 穣; 大久保 清志

JAEA-Data/Code 2009-002, 124 Pages, 2009/05


統合化燃焼計算コードシステムSWATは 我が国で広く利用される核計算コードSRACと、一点炉燃焼計算コードORIGEN2を組合せたシステムであり、使用済燃料中のウラン,プルトニウム,マイナーアクチニド,核分裂生成物の組成を評価するために利用されてきた。任意の幾何形状の燃料の燃焼を取り扱うことができ、実効断面積の作成にさまざまな近似を行う必要がない連続エネルギモンテカルロコードを燃焼計算に使用することには大きな利点がある。従来のSWATシステムの基本構想に基づいて、一点炉燃焼計算コードORIGEN2と我が国で広く利用されている連続エネルギモンテカルロコードMVPとMCNPを組合せた統合化燃焼計算コードシステムSWAT3.1を開発した。本レポートはSWAT3.1の概要と入力データの説明及び利用例を示す。



宇野 定則; 千葉 敦也; 山田 圭介; 横山 彰人; 上松 敬; 水橋 清; 北野 敏彦*; 高山 輝充*; 織茂 貴雄*; 江夏 昌志*; et al.

JAEA-Conf 2008-012, p.44 - 47, 2009/03




石島 暖大; 井岡 郁夫; 木内 清; 金子 哲治*; 大久保 努; 山本 正弘

圧力技術, 47(1), p.12 - 17, 2009/01



Development of beam generation and irradiation technology for electrostatic accelerator

山田 圭介; 宇野 定則; 千葉 敦也; 横山 彰人; 齋藤 勇一; 石井 保行; 佐藤 隆博; 大久保 猛; 上松 敬; 水橋 清

JAEA-Review 2008-055, JAEA Takasaki Annual Report 2007, P. 185, 2008/11

TIARA静電加速器において平成19年度に行ったビーム発生及び照射技術の開発の結果を報告する。タンデム加速器では、ペレットチェーンの高速回転による高電圧ターミナルの機械的振動が、加速電圧の安定度に与える影響を調べるため、ペレットチェーンの回転速度とエネルギー安定度の関係を測定した。その結果、加速電圧の安定度はチェーンの回転速度に大きく依存し、振動を抑制することで加速電圧の安定度を改善できることがわかった。また、高強度のクラスターイオンビームを得るために適した荷電変換ガスを探索するために、ヘリウムガスとタンデム加速器で通常用いられている窒素ガスを使用したときの2.5MeV-C$$_{8}$$イオンの損失割合を測定した。その結果、前者が後者より20%低く、クラスターイオン用の荷電変換ガスに適していることがわかった。シングルエンド加速器では、RFイオン源の高輝度化を目的として、1.7MeV-H$$^{+}$$ビームのエミッタンスを測定した。その結果、x方向エミッタンスはエミッタンスモニタの測定限界である6$$pi$$ mm mrad(MeV)$$^{1/2}$$以下であり、正確なエミッタンスの測定にはモニタの角度分解能の向上が必要であるということがわかった。イオン注入装置では、広範囲のイオン種,ビームエネルギー及びビーム強度で使用可能な強度分布モニタの開発のために、21個の小型ファラデーカップを2次元的に配置したマルチファラデーカップを試作し、性能評価を行った。


Operation of the electrostatic accelerators

上松 敬; 宇野 定則; 千葉 敦也; 山田 圭介; 横山 彰人; 齋藤 勇一; 石井 保行; 佐藤 隆博; 大久保 猛; 水橋 清; et al.

JAEA-Review 2008-055, JAEA Takasaki Annual Report 2007, P. 191, 2008/11

平成19年度のTIARA施設3台の静電加速器は順調に稼動し、計画されたイオン照射実験はユーザーの都合で中止したものを除いてすべて実施した。年間運転時間は、タンデム加速器,シングルエンド加速器,イオン注入装置についてそれぞれ1949, 2437, 1900時間と例年並であった。整備では、タンデム加速器のSF$$_{6}$$ガス回収装置からの微少のガス漏れの改善を行った。ガス回収装置に残留するガスが高圧であることが漏れの要因であるため、複数のパッキンを交換するとともに、残留高圧ガスをストレージタンクへ逃がす配管を増設し圧力を下げることで改善し、新ビーム開発では、イオン注入装置においてPbイオンを高温オーブン方式で生成し、1.5$$mu$$A程度の生成が可能となった。

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