Surface segregation effect for prevention of oxidation in Ni-X (X=Sn, Sb) alloy by in situ photoelectron spectroscopy

Doi, Takashi*; Yoshigoe, Akitaka

Surface and Interface Analysis, 52(12), p.1117 - 1121, 2020/12

https://doi.org/10.1002/sia.6802

Ni-base alloys has been widely used for chemical plants because of their high strength and excellent oxidation resistance. In particular, the addition of Sn and Sb in Ni-base alloys significantly improves the metal dusting resistance. It is indicated that Sn and Sb are segregated on the alloy surface in the metal dusting environment; however, the details have not been clarified yet. The behavior of the Ni-Sn and Ni-Sb alloys under a high-temperature oxidation environment was investigated by in situ X-ray photoelectron spectroscopy. It was confirmed that Sn and Sb have been segregated at the surface of their alloys during oxidation in low oxygen potential environment. These results indicate that Sn and Sb segregation improves the metal dusting resistance.

Investigation of segregation during oxidation of Ni-Cu alloy by photoelectron spectroscopy

Doi, Takashi*; Nishiyama, Yoshitaka*; Yoshigoe, Akitaka; Teraoka, Yuden

Surface and Interface Analysis, 48(7), p.685 - 688, 2016/07

https://doi.org/10.1002/sia.6001

Ni-based alloys has been widely used for plant application because of their high strength and excellent oxidation resistance. In particular, the addition of Cu in Ni-based alloys significantly improves the metal dusting resistance. It is indicated that Cu is segregated on the alloy surface in the metal dusting environment; however, the details have not been clarified yet. The behavior of Ni-2Cu alloy under a high temperature oxidation environment was investigated using X-ray photoelectron spectroscopy. It was confirmed that Cu have been segregated at the surface of Ni-2Cu alloy during oxidation. These results propose that the Cu segregation improves the metal dusting resistance.

Development of Advanced Methodology for Defect Assessment in FBR Power Plants (Phase II)

Meshii, Toshiyuki*; Watashi, Katsumi; Doi, Motoo; Hashimoto, Takashi

JNC TY4400 2004-001, 90 Pages, 2004/03

JNC-TY4400-2004-001.pdf:10.67MB

Based on the results of the Phase I of the titled research, we started Phase II scheduled to reach conclusion (develop basic methods necessary for FBR post-construction code) in three years. The following results were obtained. (1) Development of assessment procedure for multiple defects due to creep damage: We first confirmed that multiple surface cracks in axial and circumferential direction inside a cylinder can be evaluated independently by investigating multiple flaws found in a cylinder due to cyclic thermal shock. Then we developed a method to evaluate the stress intensity factors (SIFs) of the multiple circumferential cracks in a finite legth cylinder under axisymmetric loads. (2) Improving creep-fatigue crack grown (C-FCG) assessment pfodedure: We reviewed the French code A16 for flaw assessment and compared it with the JNC proposal. Since the fundamenfal philosophy for both was to evaluate the C-FCG by estimating elastic-plastic fracture mechanics parameter from the SIF, we developed a "3D crack finite element analysis system that can specify the target error in SIF." (3) Crack propagation assessment under thermal stresses (fatigue crack grown (FCG) resistace for small load): To improve accuracy of FCG assesment for components in FBR power plants (designed to minimize thermal stresses) under thermal cycles, we obtained near threshold FCG data for S55C, SUS304, HT60, SS400, 2.25Cr-1Mo, SUS316, SUS321, T91, Inconel718 by Kmax = constant test method. The results showed that FCG curves in the JSME post construction code (which is an extrapolation of the curves in ASME PVP code sec. XI) are valid in general. However, precise review of S55C, HT60's data suggested that the JSME FCG, evaluation curve may not have enough safety margin. In addition, we proposed a method to predict the decrease in the threshold SIF range DeltaKth due to high Kmax and showed its validity.

Vibration and deformation monitoring for high temperature structures by heat-resistant FBG

Shimada, Yukihiro; Masuzumi, Takashi; Nishimura, Akihiko; Doi, Motoo*; Tsukimori, Kazuyuki

no journal, , 

We performed irreversible lattice processing into the quartz board using the technique of non-heat processing which used femtosecond laser. The heat-resistant evaluation was performed for the purpose of development of heat-resistant FBG for always supervising heat transfer system vibration and modification of a high temperature structure. As a result, the intensity ratio of diffraction light did not change but after rising temperature up to 950 C showed that the system of heat-resistant FBG was effective as a local vibration of high temperature piping, and the distorted detection technique.

Influence of additive elements on initial oxidation of Ni base alloys, 1

Doi, Takashi*; Nishiyama, Yoshitaka*; Teraoka, Yuden; Yoshigoe, Akitaka

no journal, , 

no abstracts in English

Development of exposure reduction technologies by digitalization of environment and radioactive source distribution, 10; Understanding and 3D modeling of working environmental data by using deep learning

Doi, Akio*; Yamashita, Meguru*; Takahashi, Hiroki*; Kato, Toru*; Imabuchi, Takashi; Hanari, Toshihide; Tanifuji, Yuta; Ito, Rintaro

no journal, , 

no abstracts in English

Toward faster 3D environment modeling based on feature extraction results from movies; Research overview and initiatives

Nakamura, Keita*; Hanari, Toshihide; Madokoro, Hirokazu*; Imabuchi, Takashi; Kawabata, Kuniaki; Nix, S.*; Doi, Akio*

no journal, , 

This paper introduces a research effort for faster 3D environment modeling of the workspace for decommissioning activities at the Fukushima Daiichi Nuclear Power Plant, applying as input video images shot during an investigation of the reactor containment vessel and reactor building. Especially, we construct a system that allows the selection of a 3D reconstruction method with as much information as possible within a specified time limit. We challenge this study with three methods: photogrammetry, simulation, and AI technology. Finally, we aim to integrate the results of each research to build a prototype system that automatically generates a more informative 3D reconstruction result within a specified time and according to the extracted feature values.