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Geoscience Frontiers 2013年第1期4卷 105-111页

作者： Tetsuya Tokiwa kimikazu tsusaka Makoto Matsubara Taiki Ishikawa Daisuke Ogawa Horonobe Underground Research Unit Japan Atomic Energy AgencyHokkaido 098-3224Japan Geoscience Research Laboratory Kanagawa 242-0014Japan Mitsubishi Materials Techno Corporation Tokyo 102-8205Japan

This paper focuses on the formation mechanism of fractures induced by excavation of a gallery in soft sedimentary rocks in the Horonobe area of Japan. Detailed fracture mapping of the gallery indicates that the fractures consist of both pre-existing shear fractures and excavation damaged zone （EDZ） fractures. EDZ fractures correspond to weak planes associated with bedding planes or transgranular cracks. The EDZ fractures terminate against pre-existing shear fractures. Therefore, even for excavations in soft sedimentary rocks, formation of the EDZ fractures are controlled by pre-existing fractures and earlier weak planes.

关键词： Fracture Excavation damaged zone (EDZ)Weak plane Soft rock Excavation

Simulating hydraulic fracturing processes in laboratory-scale geological media using three-dimensional TOUGH-RBSN

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Journal of Rock Mechanics and Geotechnical Engineering 2018年第6期10卷 1102-1111页

作者： Daisuke Asahina Pengzhi Pan kimikazu tsusaka Mikio Takeda John E.Bolander Geological Survey of Japan IbarakiJapan State Key Laboratory of Geomechanics and Geotechnical Engineering Institute of Rock and Soil MechanicsChinese Academy of SciencesWuhan430071China INPEX Corporation TokyoJapan University of California DavisUSA

In this context, recent developments in the coupled three-dimensional(3 D) hydro-mechanical(HM)simulation tool TOUGH-RBSN are presented. This tool is used to model hydraulic fracture in geological media, as observed in laboratory-scale tests. The TOUGH-RBSN simulator is based on the effective linking of two numerical methods: TOUGH2, a finite volume method for simulating mass transport within a permeable medium; and a lattice model based on the rigid-body-spring network(RBSN) concept. The method relies on a Voronoi-based discretization technique that can represent fracture development within a permeable rock matrix. The simulator provides two-way coupling of HM processes, including fluid pressure-induced fracture and fracture-assisted flow. We first present the basic capabilities of the modeling approach using two example applications, i.e. permeability evolution under compression deformation, and analyses of a static fracturing simulation. Thereafter, the model is used to simulate laboratory tests of hydraulic fracturing in granite. In most respects, the simulation results meet expectations with respect to permeability evolution and fracturing patterns. It can be seen that the evolution of injection pressure associated with the simulated fracture developments is strongly affected by fluid viscosity.

关键词： Hydraulic fracture Crack opening TOUGH Rigid-body-spring network(RBSN) Permeability Injection pressure Fluid viscosity Hydro-mechanical(HM) processes

Nondestructive high-sensitivity measurement method for activation estimation in accelerator room concrete

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辐射防护 2020年第6期40卷 677-682页

作者： Hiroshi Matsumura Go Yoshida Akihiro Toyoda Kazuyoshi Masumoto Hajime Nakamura Taichi Miura Koichi Nishikawa Kotaro Bessho kimikazu Sasa Tetsuaki Moriguchi Fumiyoshi Nobuhara Yoko Nagashima High Energy Accelerator Research Organization(KEK) Oho 1-1Tsukuba Ibaraki 305-0801Japan University of Tsukuba 1-1-1 TennodaiTsukubaIbaraki 305-8577Japan Tokyo Nuclear Services Co. Ltd.1-3-5.TaitoTaito-kuTokyo 110-0016Japan

This study established a method for easily and quickly estimating the specific activity produced in the concrete walls and floors of accelerator rooms during long-term operation of accelerator,for advanced zoning of activated/nonactivated areas in planning the decommissioning of an *** propose a new,highly sensitive method for nondestructively estimating the specific activity in concrete that can be applied to activation *** this method,instead of direct determination of the specific activities of important long-half-life radionuclides for decommissioning,such as 152 Eu and 60 Co,we determine the specific activities of short-half-life radionuclides,24 Na and 56 Mn,in situ to obtain neutron *** obtained neutron flux and accelerator operation history yield the specific activities of 152 Eu and 60 Co for the advance zoning of activated/non-activated *** method is a powerful long-term prediction tool for concrete activation.

关键词： accelerator activation concrete specific activity decommissioning

AMS-(14)C样品制备系统的研制及其性能研究

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同位素 2021年第3期34卷 273-281页

作者：亓明丽李昭梅唐俊森魏思雨刘明吉赵振池石书林 kimikazu Sasa 沈洪涛广西师范大学物理科学与技术学院广西桂林541004 日本筑波大学应用加速器中心日本茨城305-8577 广西核物理与核技术重点实验室广西桂林541004

为了开展加速器质谱仪(accelerator mass spectrometry, AMS)在(14)C测量方面的研究,研制了可采用锌法、氢法、氢化钛法制备(14)C样品的装置,该制样系统以石英玻璃为主要结构材料,分为以下三个单元:系统真空维护单元、CO_(2)纯化单元和C... 详细信息

为了开展加速器质谱仪(accelerator mass spectrometry, AMS)在(14)C测量方面的研究,研制了可采用锌法、氢法、氢化钛法制备(14)C样品的装置,该制样系统以石英玻璃为主要结构材料,分为以下三个单元:系统真空维护单元、CO_(2)纯化单元和CO_(2)还原单元。为验证此装置的可靠性,进行了系列(14)C样品的制备实验,得到的石墨产率基本达到80%,同时对商业碳粉、树木的含碳量与实验过程中测量区域对应的CO_(2)量进行了线性拟合,结果呈现明显的线性关系。对一批标准样品和本底样品进行AMS测试,结果显示每个样品(12)C-的引出束流均大于20μA,系列空白样品的测量结果表明,^(14)C/^(12)C丰度比平均值为1.061×10^(-15),样品制备系统稳定且在制样过程中引入的碳污染较小,符合制样要求,现代木头样品的AMS绝对测量值为(9.13±0.05)×10^(-13),与预期值~9.0×10^(-13)相符合。上述结果表明,该系统结构紧凑,能避免相互污染,高效且便于操作,满足AMS对(14)C样品的测试要求。

关键词： ^(14)C样品制备 ^(14)C 加速器质谱

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加速器质谱测量^(129)Ⅰ方法的改进

核电子学与探测技术 2007年第4期27卷 740-744页

作者：周本胡長島泰夫姜山吴伟明管永精武绍勇何明袁坚阮向东関李紀笹公和高橋努崎裕貴松四雄騎玉理美智子末木啓介广西大学物理科学与工程技术学院筑波大学应用加速器部中国原子能科学研究院北京102413

在筑波大学的12UD串列加速器上开发了一套改进的129Ⅰ加速器质谱(AMS)测量方法,包括在120°磁铁后安装了一副自行设计制作有静电偏转板,有效改善了对127Ⅰ束流和129Ⅰ计数的测量;采用97MoO2分子导航束稳定加速器端电压,加速器的端电压... 详细信息

在筑波大学的12UD串列加速器上开发了一套改进的129Ⅰ加速器质谱(AMS)测量方法,包括在120°磁铁后安装了一副自行设计制作有静电偏转板,有效改善了对127Ⅰ束流和129Ⅰ计数的测量;采用97MoO2分子导航束稳定加速器端电压,加速器的端电压能稳定在几天内不超过0.1%,结合二次剥离,取得了满意的测量效果。用该方法测得AgI试剂样品的本底水平为7.83×10-13。对129Ⅰ/127Ⅰ比值范围为(4.92~0.28)×10-10的一系列样品的测量不确定度在7%以下,准确度较前有所提高。

关键词：加速器质谱 129I测量静电偏转板二次剥离