Evaluation of mechanical properties of oxide layers of fuel cladding material Zircaloy-4 and M5 oxidized under PWR condition using Nano indentation with spherical indenter

Shibata, Akira; Wakui, Takashi; Nakamura, Natsuki; Futakawa, Masatoshi; Maekawa, Katsuhiro*; Naka, Michihiro

Zairyo Shiken Gijutsu, 62(1), p.41 - 47, 2017/01

Nuclear reactor fuel cladding material has been gradually replaced from Zircaloy-4 to Zr-Nb alloys such as M5. To reveal the origin of good corrosion resistance of Zr-Nb alloys, evaluation on oxide layer of fuel cladding tube Zircaloy-4 and M5 was performed. Nano-indentation with spherical indenter was performed on oxide layer of those materials. Test results of the indentation were evaluated by the inverse analysis using Kalman filter and Finite Element Method. The results analysis shows that the oxide layer of M5 has more ductility compare from that of Zircaloy 4. Thus, oxide layer of Zircaloy4 could be injured by smaller strain compare from that of M5.

Unconventional scaling and significant enhancement of the spin Seebeck effect in multilayers

Ramos, R.*; Kikkawa, Takashi*; Aguirre, M.*; Lucas, I.*; Anadn, A.*; Oyake, Takafumi*; Uchida, Kenichi*; Adachi, Hiroto; Shiomi, Junichiro*; Algarabel, P. A.*; et al.

Physical Review B, 92(22), p.220407_1 - 220407_5, 2015/12

https://doi.org/10.1103/PhysRevB.92.220407

Mechanical property change in the region of very high-cycle fatigue

Xiong, Z.; Naoe, Takashi; Wan, T.; Futakawa, Masatoshi; Maekawa, Katsuhiro*

Procedia Engineering, 101, p.552 - 560, 2015/03

BB2014-3103.pdf:0.47MB

https://doi.org/10.1016/j.proeng.2015.02.066

Very high-cycle fatigue behaviour of SUS316L, which is used as the structural material of the spallation neutron sources, was investigated through the ultrasonic fatigue test with the strain rate of 10 s. Cross-sectional hardness distributions of the fatigue-failed specimens for solution annealed (SA) and cold worked (CW) 316L were measured to understand the cyclic hardening or softening. In addition, the tensile tests of the fatigue-failed specimens were performed at room temperature. Furthermore, the nonlinear ultrasonic system was used for evaluating the dislocation density variation. The results showed the cyclic hardening in the region of very high-cycle fatigue in the case of SA. In contrast, in the case of 10%CW, cyclic softening occurred when the number of cycles below 10 and followed by cyclic hardening. In the case of 20%CW, cyclic softening was observed when the number of cycles below 10, while cyclic hardening occurred subsequently.

First-principles study of electronic and magnetic structures of CoFeB|Ta and CoFe|TaB heterostructures

Hamada, Tomoyuki*; Ono, Takashisa*; Maekawa, Sadamichi

Molecular Physics, 113(3-4), p.314 - 318, 2014/07

https://doi.org/10.1080/00268976.2014.939114

Very high cycle fatigue in pulsed high power spallation neutron source

Xiong, Z.*; Futakawa, Masatoshi; Naoe, Takashi; Maekawa, Katsuhiro*

Advanced Materials Research, 891-892, p.536 - 541, 2014/03

https://doi.org/10.4028/www.scientific.net/AMR.891-892.536

Very high cycle fatigue degradation of type 316L austenitic stainless steel, which is used as the structural material of neutron spallation sources under intensive neutron irradiation environment, is investigated by using an ultrasonic fatigue testing machine. The strain rate imposed on the structure of neutron spallation source is almost equivalent to that produced in the testing machine. The temperature on the surface was controlled by the air-cooling. The effect of strain rate on the fatigue strength is recognized to increase the fatigue limit.

A Novel ultrasonic evaluation process for cavitation damage by combination of attenuation and higher harmonics

Wan, T.; Wakui, Takashi; Naoe, Takashi; Futakawa, Masatoshi; Maekawa, Katsuhiro*; Wan, T.*

Jikken Rikigaku, 13(4), p.387 - 394, 2013/12

http://ci.nii.ac.jp/naid/40019937781

The mercury target system is used for MW-scale neutron sources in the Japan Spallation Neutron Source. During this operation, cavitation damage is imposed on the mercury target vessel. It is very important to nondestructively evaluate the cavitation damage from the viewpoints of the structural integrity evaluation and lifetime estimation of the mercury target vessel. In this study, the cavitation damage was evaluated using a nonlinear ultrasonic method. First, the cavitation damage was imposed on plate specimens using an electro-Magnetic IMpact Testing Machine with 108 impact cycles. Nonlinear ultrasonic imaging was used to evaluate the damage. We found that the damping factor and higher harmonics of reflected waveforms from the damaged area can be used to evaluate the damage. An effective cavitation damage evaluation process has been developed based on our results. The evaluation process successfully detected minimal cavitation damage with peak-to-peak roughness of about 25 m.

Polymerization mechanism for radiation-induced grafting of styrene into Alicyclic polyimide films for preparation of polymer electrolyte membranes

Park, J.; Enomoto, Kazuyuki; Yamashita, Takashi*; Takagi, Yasuyuki*; Todaka, Katsunori*; Maekawa, Yasunari

Journal of Membrane Science, 438, p.1 - 7, 2013/07

https://doi.org/10.1016/j.memsci.2013.03.007

Alicyclic polyimides (APIs) were successfully applied to radiation-induced graft polymerization for developing polymer electrolyte membranes for fuel cells. The grafting into fully aromatized polyimide barely proceeded (grafting degrees (GDs) of less than 5%), whereas that of styrene into the API films proceeded with styrene GDs of up to 70%. In combination of electron spin resonance measurements and ultraviolet-visible (UV-VIS) spectroscopy, the radical species was identified as a long-lived intermediate and 10% of the radicals were consumed as grafting initiators. The moderate reaction conditions allowed for selective sulfonation on the polystyrene grafts, and not on the API substrates, to give API-based polymer electrolyte membranes (PEMs) with ion exchange capacities (IEC) of 1.7-2.8 mmol/g. The PEMs exhibited appropriate proton conductivity and low water uptake, together with excellent mechanical properties, compared with conventional PEMs such as Nafion.

Neutron resonance imaging of a Au-In-Cd alloy for the JSNS

Oi, Motoki; Teshigawara, Makoto; Kai, Tetsuya; Harada, Masahide; Maekawa, Fujio; Futakawa, Masatoshi; Hashimoto, Eiko*; Segawa, Mariko; Kureta, Masatoshi; Tremsin, A.*; et al.

Physics Procedia, 43, p.337 - 342, 2013/04

https://doi.org/10.1016/j.phpro.2013.03.040

The Japan Spallation Neutron Source (JSNS) at the Japan Proton Accelerator Research Complex (J-PARC) had been developed as a 1-MW spallation neutron source. A Au-In-Cd alloy has been proposed as a new decoupler material. Recently, we successfully produced the ternary Au-In-Cd alloy. The alloy composition is 74.9 at% Au, 0.5 at% In, and 24.6 at% Cd. We used the pulsed neutron imaging techniques to measure the elements in the Au-In-Cd alloy. Both a time gated camera system and a multi-channel plate (MCP) detector were used as detectors. Measurement was performed at BL10 in the JSNS. A Au-In-Cd specimen, In foil and two Au foils are used as a sample. As a results, we could obtain distribution of Au, In and Cd in the Au-In-Cd specimens distinctly.

Visibility estimation for neutron resonance absorption radiography using a pulsed neutron source

Kai, Tetsuya; Maekawa, Fujio; Oshita, Hidetoshi*; Sato, Hirotaka; Shinohara, Takenao; Oi, Motoki; Harada, Masahide; Uno, Shoji*; Otomo, Toshiya*; Kamiyama, Takashi*; et al.

Physics Procedia, 43, p.111 - 120, 2013/00

https://doi.org/10.1016/j.phpro.2013.03.014

A neutron imaging instrument is in construction at the pulsed neutron source of J-PARC. Some demonstration experiments in NOBORU/J-PARC have carried. To explore widespread applications of the newly built instruments it is indispensable to indicate the range of coverage of this technique. In the presentation, the authors describe the results of some of demonstration measurements, and then compare all elements with the values obtained by multiplying peak cross section and peak widths of neutron resonances in evaluated nuclear data libraries. This value is expected to be a good measure to exhibit visibility of each element in this technique.

Maintenance of used components in spallation neutron source; Moderator reflector and proton beam window

Teshigawara, Makoto; Kinoshita, Hidetaka; Wakui, Takashi; Meigo, Shinichiro; Seki, Masakazu; Harada, Masahide; Ito, Manabu; Suzuki, Toru; Ikezaki, Kiyomi; Maekawa, Fujio; et al.

JAEA-Technology 2012-024, 303 Pages, 2012/07

JAEA-Technology-2012-024.pdf:46.04MB

3 GeV Protons with 1 MW beam power are irradiated to mercury target of spallation neutron source in Materials and Life science Facility (MLF), which is one of facilities of J-PARC. Irradiated components, such as target container, moderator, reflector and proton beam window, are needed to replace periodically due to irradiation damage of high energy protons and neutrons. These used components are replaced remotely because of highly activated. Maintenance scenario was settled so as to handle these components. Required remote handling machines were designed and installed in hot cell and other room of the MLF. We performed remote handling tests by using actual components to confirm the design. We report results, such as replacement procedure, trouble and its solution, etc., for moderator, reflector and proton beam window in order to provide the handling of actual used components.