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X-ray synchrotron diffractionLi, H.*; Liu, Y.*; Zhao, W.*; Liu, B.*; Tominaga, Aki; Shobu, Takahisa; Wei, D.*
International Journal of Plasticity, 165, p.103612_1 - 103612_20, 2023/06
Times Cited Count：2 Percentile：78.7(Engineering, Mechanical)In order to clarify the strength properties of Co-free maraging steel, tensile experiment using high energy synchrotron X-ray diffraction was performed. Diffraction profiles from the martensitic and austenitic phases were obtained, and their strength and width were observed to vary as loading. Analysis of the diffraction profiles showed that the content of martensite in the as-aged material decreased slowly at low stress levels and decreased rapidly at high stress levels. On the other hand, the austenite phase in the as-solution materials was significantly transformed the martensite phase as the stress increased. It was clarified to be responsible for their respective strength properties.
Tamura, Koji; Oba, Hironori; Saeki, Morihisa; Taguchi, Tomitsugu*; Lim, H. H.*; Taira, Takunori*; Wakaida, Ikuo
Journal of Nuclear Science and Technology, 58(4), p.405 - 415, 2021/04
Times Cited Count：12 Percentile：84.32(Nuclear Science & Technology)Radiation dose rate effects on the properties of a compact fiber-optic laser-induced breakdown spectroscopy (LIBS) system with a monolithic Nd:YAG/Cr:YAG composite ceramics were investigated for remote analysis in hazardous environment. To investigate radiation effects on the LIBS signal, properties related to the Nd:YAG laser operation such as oscillation threshold, output energy, oscillation timing, temporal pulse shape, and beam profile were measured as a function of the radiation dose rate from 0 to 10 kGy/hr in view of their influences to the signal. LIBS spectra of zirconium metal were measured under irradiation. Although signal intensity decreased considerably by irradiation, informative spectra were well obtained even at the maximum radiation dose rate. From the comparison of the LIBS-related parameters among the laser properties, signal reduction was mainly ascribed to the pulse energy reduction. Scintillation emission spectra were also measured from the ceramics during the irradiation, where the signal intensity increased linearly with the dose rate. The results show that the developed system.
Kuwabara, Kazumichi; Sato, Toshinori; Sanada, Hiroyuki; Takayama, Yusuke
JAEA-Research 2015-005, 378 Pages, 2015/07
JAEA-Research-2015-005.pdf:125.5MB
JAEA-Research-2015-005.zip:0.53MB
This report presents the results of following rock mechanical investigations conducted at the -500m Stage. (1) Laboratory tests using cores and block samples obtained at the -500m Stage. (2) In-situ stress measurement using Compact Conical-ended Borehole Overcoring (CCBO) method at the -500m Stage. (3) In-situ stress measurements using Differential Strain Curve Analysis(DSCA) method at the -500m Stage. (4) Development of rock mechanical model.
Okuno, Kenji; *; Ohira, Shigeru; Naruse, Yuji
Journal of Nuclear Science and Technology, 28(6), p.509 - 516, 1991/06
no abstracts in English
Wakaida, Ikuo; Akaoka, Katsuaki; Miyabe, Masabumi; Oba, Hironori; Saeki, Morihisa; Ito, Chikara; Oba, Masaki; Kato, Masaaki
no journal, ,
In the decommissioning of "Fukushima Daiichi Atomic Power Plant", it will be difficult work by the extremely high radioactivity from fission products and meltdown nuclear fuel debris. Technical innovations and some breakthrough will be indispensable for a safety accomplishment of this work. For the basic R&D on the decommissioning, Japan Atomic Energy Agency has opened the new research center "Collaborative Laboratories for Advanced Decommissioning Science". The development of onsite and in-situ analysis of fuel debris is one of the most important for the planning and working of the decommissioning. Quick, easy, non-contact, no-preparation, direct and remote analysis technique by Laser Induced Breakdown Spectroscopy (LIBS) based on radiation resistant optical fiber will be now under developing. Pulsed Nd:YAG laser will be propagated though an optical fiber and focused on the sample. Plasma emission produced by the laser on the surface of the sample is collected by the same focusing lens, propagated through the same optical fiber and put into the spectrometer. Elemental identification and the composition are evaluated by specific atomic emission line and its intensity. Under strong irradiation condition; dose rate of 10 kGy/h and after total dose of 2 MGy, radiation resistant optical fiber had good transmission, no damage by laser light propagation, and had good performance for plasma emission spectroscopy. In addition, we have successfully observed and identified the specific spectra of Zr and U from the simulated sample of molten debris made by sintered oxide of Zr and U which is the raw materials of the fuel assembly. Quantitative analysis of the composition ratio of Zr/U has been also evaluated from the intensity ratio of specific emission lines.
Wakaida, Ikuo; Akaoka, Katsuaki; Miyabe, Masabumi; Oba, Hironori; Saeki, Morihisa; Ito, Chikara; Oba, Masaki; Kato, Masaaki
no journal, ,
For the decommissioning of "Fukushima Daiichi Nuclear Power Plant", development of onsite and in-situ remote diagnostic/analysis techniques under high radioactive environments will be strongly required. For the basic R&D on the decommissioning, Japan Atomic Energy Agency has opened the new research center "Collaborative Laboratories for Advanced Decommissioning Science". The concept of probing by light and diagnostic by light will be one of the powerful choices to accomplish these requirements. So, we are now developing the remote diagnostic technique for onsite, in-situ monitoring of nuclear debris. Optical Fiber based LIBS probe made by radiation resistant optical fiber was constructed, and we have successfully observed some specific spectra from the simulated sample of molten debris made by sintered oxide of Zr and U under the severe environment such as radioactive condition of 10 kGy/h and after total dose of 2 MGy.
Wakaida, Ikuo; Oba, Hironori; Akaoka, Katsuaki; Miyabe, Masabumi; Saeki, Morihisa; Oba, Masaki; Ito, Chikara; Kato, Masaaki
no journal, ,
Wakaida, Ikuo; Oba, Hironori; Akaoka, Katsuaki; Oba, Masaki; Matsumoto, Ayumu; Miyabe, Masabumi; Ikeda, Yuji*; Sakka, Tetsuo*; Taira, Takunori*
no journal, ,
For the decommissioning of "Fukushima Daiichi Nuclear Power Station (F1NPS)", widely basic R&D and matting for actual application for decommissioning technology will be strongly required. CLADS/JAEA is one of the key institute for strategic promotion of Decommissioning Science on F1NPS. As for the development of rapid, easy, onsite and in-situ remote diagnostic/analysis techniques under extremely high radioactive condition, the concept of probing by light and diagnostic by light with radiation resistant optical fiber will be one of the simple, powerful and applicable choices as the innovative development based on laser induced breakdown spectroscopy (LIBS) technology. Optical fiber based LIBS is developed for in-core and in-situ elemental analysis of debris and its activity is performed under severe environmental conditions such as high radiation field of about 10kGy/h and under water. Long pulse laser, microwave assisted LIBS and microchip laser are also introduced for more high sensitivity.
Wakaida, Ikuo; Oba, Hironori; Akaoka, Katsuaki; Oba, Masaki; Miyabe, Masabumi; Matsumoto, Ayumu
no journal, ,
Radiation resistant optical fiber based laser induced breakdown spectroscopy (Fiber LIBS) is developed for in-core and in-situ elemental analysis of debris and its activity is performed under severe environmental conditions such as high radiation field of about 10 kGy/h and under water. Long pulse laser, microwave assisted LIBS for more high sensitivity and liquid sample application are also introduced. Long-pulse laser with the pulse duration about 100 ns will be introduced to compensate the delivery power loss and/or to enhance the emission signal. microwave assisted LIBS technique coupled with simple antenna for the combination use with fiber LIBS will be under developing, and about ten times enhancement was observed under the atmosphere condition. For the application to the liquid phase sample, especially for the analysis of the polluted cooling water, the thin-sheet liquid jets will be also introduced as the convenience and high sensitive monitoring for dissolved elements of nuclear fuel debris.
Wakaida, Ikuo; Oba, Hironori; Akaoka, Katsuaki; Miyabe, Masabumi; Oba, Masaki; Taira, Takunori*
no journal, ,
Wakaida, Ikuo; Oba, Hironori; Akaoka, Katsuaki; Miyabe, Masabumi; Oba, Masaki; Matsumoto, Ayumu*; Sakka, Tetsuo*; Taira, Takunori*; Ikeda, Yuji*
no journal, ,
and GdO
Tsuchimochi, Ryota; Sugata, Hiromasa*; Sunaoshi, Takeo*
no journal, ,
Solid solution reaction of MOX pellet procceds at sintering process, but at what temperature and how fast the reaction proceeds have not been understood. CeO and GdO were used as simulating materials of UO and PuO, respectively. A shrinkage rate measurement on CeO and GdO mixed compact was carried out in the temperature range of 300K to 1923K. The shringage curve has two positive peaks at around 1213K and 1600K. High temperature X-ray diffraction measurements on CeO and GdO mixed powder were carried out at 1213K and 1600K for 240 minutes. The solid solution formation was observed at 1600K, but not at 1213K. It is considered that the first shrinkage region at 1213K was caused by initial sintering and the second region at 1600K was caused by mid-final sintering.
Wakaida, Ikuo; Oba, Hironori; Oba, Hironori*; Akaoka, Katsuaki; Karino, Takahiro; Nakanishi, Ryuzo*; Sakamoto, Kan*; Ikeda, Yuji*; Taira, Takunori*
no journal, ,
Wakaida, Ikuo; Oba, Hironori; Akaoka, Katsuaki; Karino, Takahiro; Nakanishi, Ryuzo*; Sakamoto, Kan*; Ikeda, Yuji*; Taira, Takunori*
no journal, ,
Wakaida, Ikuo; Oba, Hironori; Akaoka, Katsuaki; Karino, Takahiro; Sakamoto, Kan*; Nakanishi, Ryuzo*; Kashiwakura, Shunsuke*; Taira, Takunori*; Ikeda, Yuji*; Deguchi, Yoshihiro*
no journal, ,
We are developing remote in-situ analysis by laser induced breakdown spectroscopy (LIBS) for simple in-situ screening analysis of fuel debris in the decommissioning of the Fukushima Daiichi Nuclear Power Station. For various application scenarios, microchip laser based LIBS for ultra-long distance analysis, microwave assisted LIBS for signal enhancement, and long/short double pulse laser LIBS for water-containing samples are developing as the fiber-optic LIBS system. To have the reliability, valuation with nuclear fuel materials and spent fuel, and radiation resistance test by 
Co irradiation will be planed. As a challenging trial, a development of Machine learning technique has introduced for automatically analysis of LIBS spectra.
