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論文

Decommissioning robot manipulator for fuel debris retrieval

中島 慎介*; Moro, A.*; 小松 廉*; Faragasso, A.*; 松日楽 信人*; Woo, H.*; 川端 邦明; 山下 淳*; 淺間 一*

Proceedings of International Topical Workshop on Fukushima-Daiichi Decommissioning Research 2024 (FDR2024) (Internet), 4 Pages, 2024/10

Fuel debris retrieval at the bottom of the primary containment vessel (PCV) is one of the significant tasks for the decommissioning of the nuclear power plant and in particular for 1F. It is challenging for conventional manipulators to perform the retrieval process due to the presence of radiation, water leakage, and poor lighting conditions. We tackle those problems with the design and fabrication of a novel mechanical manipulator and its control and navigation algorithm. Continuous Variable Transmission (CVT)-based actuation improves the robot's shock resistance. AI-based navigation algorithm enables semiautonomous navigation and grasping in the cluttered environment inside the PCV.

論文

In-situ neutron diffraction study of serration-involved ultra-cryogenic deformation behavior at 15 K

Kim, Y. S.*; Chae, H.*; Lee, D.-Y.*; Han, J. H. *; Hong, S.-K.*; Na, Y. S.*; Harjo, S.; 川崎 卓郎; Woo, W.*; Lee, S.-Y.*

Materials Science & Engineering A, 899, p.146453_1 - 146453_7, 2024/05

 被引用回数:1 パーセンタイル:0.00(Nanoscience & Nanotechnology)

This work focused on the mechanical properties and serration-involved deformation behavior of advanced alloys at 15 K. Evolution of stacking faults and $$varepsilon$$-martensite improved the mechanical performance of CoCrNi alloys, and significant strain-induced martensite transformation of DED-SS316L led to superior strength and strain hardening. A magnitude in stress drop was governed by dislocation density, phase type, and lattice defects, irrespective of processing method. FCC {200} notably was influenced recovery behavior after stress drop, and the contribution of strain energy density by serration on tensile toughness was the greatest for HR-CoCrNi.

論文

Competitive strengthening between dislocation slip and twinning in cast-wrought and additively manufactured CrCoNi medium entropy alloys

Woo, W.*; Kim, Y. S.*; Chae, H. B.*; Lee, S. Y.*; Jeong, J. S.*; Lee, C. M.*; Won, J. W.*; Na, Y. S.*; 川崎 卓郎; Harjo, S.; et al.

Acta Materialia, 246, p.118699_1 - 118699_13, 2023/03

 被引用回数:36 パーセンタイル:99.47(Materials Science, Multidisciplinary)

In situ neutron diffraction experiments have been performed under loading in cast-wrought (CW) and additively manufactured (AM) equiatomic CoCrNi medium-entropy alloys. The diffraction line profile analysis correlated the faulting-embedded crystal structure to the dislocation density, stacking/twin fault probability, and stacking fault energy as a function of strain. The results showed the initial dislocation density of 1.8$$times$$10$$^{13}$$ m$$^{-2}$$ in CW and 1.3$$times$$10$$^{14}$$ m$$^{-2}$$ in AM. It significantly increased up to 1.3$$times$$10$$^{15}$$ m-$$^{-2}$$ in CW and 1.7$$times$$10$$^{15}$$ m$$^{-2}$$ in AM near fracture. The dislocation density contributed to the flow stress of 470 MPa in CW and 600 MPa in AM, respectively. Meanwhile, the twin fault probability of CW (2.7%) was about two times higher than AM (1.3%) and the stacking fault probability showed the similar tendency. The twinning provided strengthening of 360 MPa in CW and 180 MPa in AM. Such a favorable strengthening via deformation twinning in CW and dislocation slip in AM was attributed to the stacking fault energy. It was estimated as 18.6 mJ/m$$^{2}$$ in CW and 37.5 mJ/m$$^{2}$$ in AM by the strain field of dislocations incorporated model. Dense dislocations, deformation twinning, and atomic-scale stacking structure were examined by using electron backscatter diffraction (EBSD) and transmission electron microscopy (TEM).

論文

Multiple deformation scheme in direct energy deposited CoCrNi medium entropy alloy at 210K

Kim, Y. S.*; Chae, H.*; Woo, W.*; Kim, D.-K.*; Lee, D.-H.*; Harjo, S.; 川崎 卓郎; Lee, S. Y.*

Materials Science & Engineering A, 828, p.142059_1 - 142059_10, 2021/11

 被引用回数:28 パーセンタイル:89.58(Nanoscience & Nanotechnology)

CoCrNi medium entropy alloy (MEA) and stainless steel 316L (SS316L) were manufactured by direct energy deposition of additive manufacturing (DED-AM). Exceptional mechanical properties of DED CoCrNi at 210K were achieved by the activities of a multiple deformation scheme that changed from dislocation slip to twinning-induced plasticity followed by transformation-induced plasticity. While SS316L at room temperature has micro-twins, CoCrNi at 210K exhibited nano-twins, resulting from lower stacking fault energy. Moreover, transformed hexagonal close-packed (HCP) phases were found near the face-centered cubic (FCC) {111} grain boundaries, where remarkable stacking faults and severe lattice distortion were measured.

論文

Effect of the difference in strength of hard and soft components on the synergetic strengthening of layered materials

Kim, J. G.*; Bae, J. W.*; Park, J. M.*; Woo, W.*; Harjo, S.; Lee, S.*; Kim, H. S.*

Metals and Materials International, 27(2), p.376 - 383, 2021/02

 被引用回数:10 パーセンタイル:49.25(Materials Science, Multidisciplinary)

Heterogeneous structured materials achieve a combination of high strength and extreme ductility due to synergetic strengthening driven by conditions in the interfacial region. Although the origin of synergetic strengthening has been revealed to be strain incompatibility in the interfacial region, the effect of the strength difference between hard and soft phases on strengthening has not been investigated well. In the work reported in the present paper, the effect of the difference in strength of the hard and soft phases on synergetic strengthening was investigated by conducting in situ neutron diffraction tensile tests. As a result, it was determined that the dislocation density in a layered sheet of high Mn (HMn) steel/interstitial free (IF) steel is higher than that in a layered sheet of HMn/low carbon steel. The big difference in mechanical properties between HMn steel and IF steel induces a high stress gradient and results in additional dislocations.

論文

Comparison of dislocation density, twin fault probability, and stacking fault energy between CrCoNi and CrCoNiFe medium entropy alloys deformed at 293 and 140K

Woo, W.*; Naeem, M.*; Jeong, J.-S.*; Lee, C.-M.*; Harjo, S.; 川崎 卓郎; He, H.*; Wang, X.-L.*

Materials Science & Engineering A, 781, p.139224_1 - 139224_7, 2020/04

 被引用回数:52 パーセンタイル:95.04(Nanoscience & Nanotechnology)

To elucidate deformation behavior behind the exceptional mechanical properties of CrCoNi based medium entropy alloys, the deformation related microstructural parameters were determined by using in situ neutron diffraction and peaks profile analysis methods. Superior tensile strength and elongation of the CrCoNi alloy is relevant to higher twin fault probability ($$P_{tw}$$, up to 3.8%) and dislocation density ($$rho$$, up to 9.7 $$times$$ 10$$^{15}$$ m$$^{-2}$$) compared to those (1.3% and 3.4 $$times$$ 10$$^{15}$$ m$$^{-2}$$, respectively) of the CrCoNiFe at 293K. Meanwhile, at 140K, the $$P_{tw}$$ of the CrCoNiFe significantly increased up to 4.4% with the stable $$rho$$ of $$sim$$5.0 $$times$$ 10$$^{15}$$ m$$^{-2}$$ and its mechanical properties overwhelm those of the CrCoNi at 273K. Such twinning dominant deformation mechanism at low temperature is also assured by lower stacking fault energy (SFE) of the CrCoNiFe at 140K compared to those of the CrCoNi and CrCoNiFe alloys at 293K.

論文

On the phase transformation and dynamic stress-strain partitioning of ferrous medium-entropy alloy using experimentation and finite element method

Bae, J. W.*; Jung, J.*; Kim, J. G.*; Park, J. M.*; Harjo, S.; 川崎 卓郎; Woo, W.*; Kim, H. S.*

Materialia, 9, p.100619_1 - 100619_15, 2020/03

In the present study, an integrated experimental-numerical analysis on ferrous medium-entropy alloy (FMEA) was conducted to understand the micromechanical response of the constituent phases in the FMEA at -137$$^{circ}$$C. The initial face-centered cubic (FCC) single phase microstructure of the FMEA was transformed to body-centered cubic (BCC) martensite during tensile deformation at -137$$^{circ}$$C, resulting in improved low-temperature mechanical properties. The microstructure evolution due to deformation-induced phase transformation mechanism and strain partitioning behavior was analyzed using ${it ex situ}$ electron backscatter diffraction. The mechanical responses related to the stress partitioning between constituent phases and deformation-induced transformation rate were measured using ${it in situ}$ neutron diffraction in combination with the nanoindentation analysis.

論文

Stacking fault energy analyses of additively manufactured stainless steel 316L and CrCoNi medium entropy alloy using in situ neutron diffraction

Woo, W.*; Jeong, J.-S.*; Kim, D.-K.*; Lee, C. M.*; Choi, S.-H.*; Suh, J.-Y.*; Lee, S. Y.*; Harjo, S.; 川崎 卓郎

Scientific Reports (Internet), 10(1), p.1350_1 - 1350_15, 2020/01

 被引用回数:77 パーセンタイル:94.68(Multidisciplinary Sciences)

Stacking fault energies (SFE) were determined in additively manufactured (AM) stainless steel (SS 316 L) and equiatomic CrCoNi medium-entropy alloys. In situ neutron diffraction was performed to obtain a number of faulting-embedded diffraction peaks simultaneously from a set of (hkl) grains during deformation. The peak profiles diffracted from imperfect crystal structures were analyzed to correlate stacking fault probabilities and mean-square lattice strains to the SFE. The result shows that averaged SFEs are 32.8 mJ/m$$^2$$ for the AM SS 316 L and 15.1 mJ/m$$^2$$ for the AM CrCoNi alloys. Meanwhile, during deformation, the SFE varies from 46 to 21 mJ/m$$^2$$ (AM SS 316 L) and 24 to 11 mJ/m$$^2$$ (AM CrCoNi) from initial to stabilized stages, respectively. The transient SFEs are attributed to the deformation activity changes from dislocation slip to twinning as straining.

論文

Plastic anisotropy and deformation-induced phase transformation of additive manufactured stainless steel

Chae, H.*; Huang, E.-W.*; Jain, J.*; Wang, H.*; Woo, W.*; Chen, S.-W.*; Harjo, S.; 川崎 卓郎; Lee, S. Y.*

Materials Science & Engineering A, 762, p.138065_1 - 138065_10, 2019/08

 被引用回数:47 パーセンタイル:91.59(Nanoscience & Nanotechnology)

Plastic anisotropy and deformation-induced phase transformation of additively manufactured (AM) stainless steels were investigated via in-situ neutron diffraction, electron backscatter diffraction, metallography, and fractography. Two types of tensile specimens were manufactured: (1) One sample was vertically fabricated with its tensile axis parallel to the z-direction (AM-V), (2) The other sample was horizontally fabricated with its tensile axis perpendicular to the z-direction (AM-H). A commercial 15-5PH stainless steel (CA) was used for comparison. AM steel revealed enhanced yield strength, tensile strength, and uniform elongation over CA, which was mainly due to grain refinement and transformation induced plasticity (TRIP). Different onsets of strain nonlinearity between AM-V and AM-H were closely related to martensitic phase transformation.

論文

Synergetic strengthening of layered steel sheet investigated using an ${it in situ}$ neutron diffraction tensile test

Kim, J. G.*; Bae, J. W.*; Park, J. M.*; Woo, W.*; Harjo, S.; Chin, K.-G.*; Lee, S.*; Kim, H. S.*

Scientific Reports (Internet), 9, p.6829_1 - 6829_7, 2019/05

 被引用回数:15 パーセンタイル:52.14(Multidisciplinary Sciences)

Synergetic strengthening induced by plastic strain incompatibility at the interface, and the resulting extra geometrically necessary dislocations (GNDs) generated during plastic deformation, were investigated to understand the origin of extra strength in heterogeneous structured (Hs) materials. The mechanism of extra GND generation in twinning-induced plasticity (TWIP)-interstitial free (IF) steel layered sheet was quantitatively analyzed by conducting ${it in situ}$ neutron scattering tensile test. The extra GNDs can be correlated with the back-stress evolution of the HS materials, which contributes to the strength of layered materials. Because of the back-stress evolution caused by load partitioning, the strength of TWIP-IF layered steel is higher than the strength estimated by the rule-of-mixtures.

論文

${it In situ}$ neutron diffraction study of phase stress evolution in a ferrous medium-entropy alloy under low-temperature tensile loading

Bae, J. W.*; Kim, J. G.*; Park, J. M.*; Woo, W.*; Harjo, S.; Kim, H. S.*

Scripta Materialia, 165, p.60 - 63, 2019/05

 被引用回数:33 パーセンタイル:84.68(Nanoscience & Nanotechnology)

Phase stress evolution of face-centered cubic (FCC) and deformation-induced body-centered cubic (BCC) phases was measured in recently developed ferrous medium-entropy alloy. This was done during tensile deformation at -137$$^{circ}$$C using ${it in situ}$ neutron diffraction measurement for the quantitative interpretation of the role of martensitic transformation on the improved low-temperature tensile properties. The strain-hardening rate curve exhibits two-stage hardening behavior, and the phase stress and stress contribution from the BCC phase increases significantly while that from FCC phase decreases during plastic deformation. This is a direct demonstration that BCC phase contributes significantly to the increase in strength and strain hardening.

論文

Spontaneous decays of magneto-elastic excitations in non-collinear antiferromagnet (Y,Lu)MnO$$_{3}$$

Oh, J.*; Le, M. D.*; Nahm, H.-H.*; Sim, H.*; Jeong, J.*; Perring, T. G.*; Woo, H.*; 中島 健次; 河村 聖子; Yamani, Z.*; et al.

Nature Communications (Internet), 7, p.13146_1 - 13146_6, 2016/10

 被引用回数:60 パーセンタイル:86.42(Multidisciplinary Sciences)

(Y,Lu)MnO$$_{3}$$において、磁気励起とフォノンが結合する磁気弾性励起を中性子散乱により観測し、その量子的振る舞いを調べた。

口頭

Navigation and control of a novel shock-resistant mechanical manipulator for fuel debris retrieval

中島 慎介*; Moro, A.*; 小松 廉*; Faragasso, A.*; 松日楽 信人*; Woo, H.*; 川端 邦明; 山下 淳*; 淺間 一*

no journal, , 

The aim of this research is to develop a novel manipulator for retrieving fuel debris on the Fukushima Daiichi Nuclear Power Plant (1F) as shown in Figure 1. We designed a shock-resistant CVT (Continuously Variable Transmission) robot in collaboration with the University of Sussex.

口頭

Navigation and control of a novel shock-resistant mechanical manipulator for fuel debris retrieval

中島 慎介*; 小松 廉*; Moro, A.*; Fraggasso, A.*; Woo, H.*; 松日楽 信人*; 川端 邦明; 淺間 一*

no journal, , 

The aim of this research is to develop a novel manipulator for retrieving fuel debris on the Fukushima Daiichi Nuclear Power Plant (1F) as shown in Figure 1. We designed a shock-resistant CVT (Continuously Variable Transmission) robot in collaboration with the University of Sussex.

口頭

Remote control technology for monitoring inside RPV pedestal during retrieval of fuel debris

松日楽 信人*; 小松 廉*; 中島 慎介*; 山下 淳*; 福井 類*; 高橋 浩之*; 島添 健次*; Woo, H.*; 田村 雄介*; 高橋 隆行*; et al.

no journal, , 

This research aims to develop human resources in the field of remote technology for the decommissioning of the Fukushima Daiichi Nuclear Power Plant (1F). We conduct research on a monitoring platform for fuel debris removal. We expect to develop research personnel through participation in projects, lectures, and facility tours.

口頭

Navigation and control of a novel shock-resistant mechanical manipulator for fuel debris retrieval

中島 慎介*; 小松 廉*; Moro, A.*; Faragasso, A.*; Woo, H.*; 川端 邦明; 淺間 一*

no journal, , 

This research aims at developing a novel manipulator for retrieving fuel debris on the Fukushima Daiichi Nuclear Power Plant (1F) as shown in Figure 1. We conduct research on designing shock-resistant CVT (Continuously Variable Transmission) robot in collaboration with the University of Sussex. Our main focus is on navigation and control.

口頭

Remote control technology for monitoring inside RPV pedestal during retrieval of fuel debris; Prototype experiments

松日楽 信人*; 小松 廉*; 中島 慎介*; 山下 淳*; 福井 類*; 高橋 浩之*; 島添 健次*; Woo, H.*; 田村 雄介*; 高橋 隆行*; et al.

no journal, , 

本プロジェクトでは、福島第一原子力発電所の廃炉に向けた遠隔技術分野の人材育成を目的として、燃料デブリ取り出しのためのモニタリングプラットフォームの研究を行っている。本発表では、開発したモニタリングプラットフォームのプロトタイプを用いた実験と各要素技術について説明する。また、本プロジェクトへの参加、講演会での発表、関連施設の見学などを通して、研究人材の育成を期待している。

口頭

Remote control technology for monitoring inside RPV pedestal during retrieval of fuel debris; Integrated experiments

松日楽 信人*; 小松 廉*; 中島 慎介*; 山下 淳*; 福井 類*; 高橋 浩之*; 島添 健次*; Woo, H.*; 田村 雄介*; 高橋 隆行*; et al.

no journal, , 

This research aims to develop human resources in the field of remote technology for the decommissioning of the Fukushima Daiichi Nuclear Power Plant. We conduct research on a monitoring platform for fuel debris removal. Here, the developments on prototype experiments were described. We expect to develop research personnel through participation in projects, lectures, and facility tours.

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