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Wakui, Takashi; Yamasaki, Kazuhiko*; Futakawa, Masatoshi
Advanced Experimental Mechanics, 7, p.103 - 109, 2022/08
As part of the development of technique to cut and reduce the volume of highly radioactive components in the closed space, pulsed Nd:YAG laser was irradiated to radiation shielding glasses with the different lead content in the different irradiation condition; power and number of irradiation. The large black irradiated area with concave shape and cracks around it occurred with an increase of the lead content, power and number of irradiation. General mechanical properties in unirradiated and irradiated area were investigated to investigate the influence of mechanical properties on the irradiation damage. The thermal impact fracture toughness calculated based on the estimated mechanical properties decreased with increasing the lead content. The micro hardness in black irradiated area was 10% smaller than that in the unirradiated area. The change of the mechanical property due to the laser irradiation was confirmed.
Wakui, Takashi; Yamasaki, Kazuhiko*; Futakawa, Masatoshi
Jikken Rikigaku, 22(2), p.96 - 104, 2022/06
Pulsed laser irradiation and indentation tests on radiation shielding glasses and a lead-free glass were carried out. The size of irradiation damage of the glass with high lead content was larger than that with low content. The micro plastic behavior of glasses was quantitatively determined using the inverse analyses based on indentation results. Flow stress decreased with an increase of lead content and that in irradiated area was lower than that in unirradiated area. On the other hand, plastic flow resistance increased with an increase of the lead content and that in irradiated area was higher than that in unirradiated area. Fracture energy and critical size of plastic zone around tip of crack in unirradiated and irradiated areas were calculated based on experimental results including constants evaluated using the inverse analysis. These values decreased with an increase of the lead content and these values in irradiated area were lower than that in unirradiated area.
Yamasaki, Kazuhiko*; Kato, Hironori*; Futakawa, Masatoshi; Teshigawara, Makoto
Jikken Rikigaku, 21(4), p.308 - 313, 2021/12
In this study, coloration and damage of radiation-resistant lead glasses by nanosecond pulse laser with visible wavelength are evaluated. Three kinds of radiation resistance glasses with different lead content: PbO-55 wt%, 71 wt% and PbO free glass are used. As a result, the transitional coloration and damage formation with phase differences had observed by nanosecond pulsed laser irradiation at peak power of 1 kW. Although high-lead concentration glass has lower thresholds for coloration in laser intensity, damage-formation thresholds for both PbO glasses were almost the same. On the other hand, no change was observed after laser-irradiation to PbO-free glass. In addition, photochemical and thermal reaction of PbO by nanosecond pulsed laser irradiation is considered from the result of intensity change at wave numbers 200-500
and 1000 cm in Raman spectrums.
Naoe, Takashi; Teshigawara, Makoto; Futakawa, Masatoshi; Mizutani, Haruki; Muramatsu, Toshiharu; Yamada, Tomonori; Ushitsuka, Yuji*; Tanaka, Nobuatsu*; Yamasaki, Kazuhiko*
Proceedings of 8th International Congress on Laser Advanced Materials Processing (LAMP 2019) (Internet), 5 Pages, 2019/05
Laser cutting is one of the options in the disposal of radio-active waste, such as spallation neutron target vessel in J-PARC, etc. Due to unique characteristic of laser, such as non-contact system, it is more easily to provide remote-controlled system in comparison with conventional one, such as mechanical cutting machine, etc. However, a demerit of laser cutting is the sputter and fume caused by laser cutting, resulting in contamination with radio-active materials its surroundings. Recently it was developed that the spatter suppression technique by controlling laser beam profile in laser welding process. In order to apply this suppression technique to laser cutting, first of all, we attempted to observe the phenomenon at melting area during laser cutting using a high-speed video camera in order to make the physical model. The result showed that the appearance of fume and sputter were independently confirmed in the time evolution.
Mitsuhara, Masatoshi*; Harada, Erika*; Yamasaki, Shigeto*; Ikeda, Kenichi*; Hata, Satoshi*; Nakashima, Hideharu*; Otsuka, Satoshi; Kaito, Takeji
Kashika Joho Gakkai-Shi, 31(122), p.98 - 103, 2011/07
no abstracts in English
Yamasaki, Kazuhiko*; Chikazawa, Takahiro*; Tamaki, Yoshihisa*; Kikuchi, Toshiaki*; Hanzawa, Masatoshi*; Morita, Yasuji; Ikeda, Yasuhisa*
Progress in Nuclear Energy, 47(1-4), p.414 - 419, 2005/00
Times Cited Count：3 Percentile：24.22(Nuclear Science & Technology)The simple reprocessing method based on precipitation using N-cyclohexyl-2-pyrrolidone (NCP) as a selective precipitant for U and Pu ions from dissolved solutions of spent FBR fuels has been developed. On the basis of fundamental studies on precipitation behaviors, we designed and built up the scaled-up laboratory equipments (1/20-scale of future plant capacity of 200 tHM/y) to evaluate technological and economical feasibility. This system, which mainly consists of a precipitator and a precipitate separator, should be operated continuously from economical reasons. From the experimental results, it was confirmed that the precipitator is capable of producing UO
-NCP precipitate stably with stipulated residence time (approximately 30 min), and the precipitate separator has the highly efficient separation of precipitate from the slurry. Furthermore, the parametric experiments indicated that the rinsing operation increased the efficiency in decontamination of FP elements.
Kikuchi, Toshiaki*; Yamasaki, Kazuhiko*; Kusama, Makoto*; Chikazawa, Takahiro*; Tamaki, Yoshihisa*; Hanzawa, Masatoshi*; Koshino, Nobuyoshi*; Asanuma, Noriko*; Harada, Masayuki*; Kawata, Yoshihisa*; et al.
no journal, ,
no abstracts in English
Osone, Ryuji; Bucheeri, A.; Kurishita, Hiroaki*; Kato, Masahiro*; Yamasaki, Kazuhiko*; Maekawa, Katsuhiro*; Naoe, Takashi; Futakawa, Masatoshi
no journal, ,
Liquid mercury target system for high power spallation neutron sources is being developed. When high intensity proton beams are injected into the target, pressure waves are generated by the thermal shock in mercury and pitting damage will be imposed on the target vessel. Bubble injection into mercury is effective to mitigate the pressure waves. In this work, we propose a method of fabricating meso-nozzle for bubble injection. The method is based on powder metallurgy by inserting thin glass fibers into a metal powder matrix to create a green compact, followed by sintering at a temperature between the melting points of the powder and the fiber. SUS316L and molybdenum powders were used as the nozzle matrix materials. In order to investigate optimum sintering condition, experiments were performed at different combination of pressing load and sintering temperature. We found that in molybdenum high relative density and straight hole with circlar cross section were obtained.
Katayama, Masaharu*; Takamatsu, Kuniyoshi; Sawa, Kazuhiro; Takagi, Naoyuki*; Ooka, Yasunori*; Yamasaki, Masatoshi*
no journal, ,
As collaborative research project by Japan Atomic Energy Agency, Toyota Tsusho Corporation and Nuclear Fuel Industries, Ltd., new utilizations of HTGR and new R&D of a cooperative relationship between car industries and HTGR are presented. Specifically, we showed the results of feasibility study on material creation and new-type fuel utilization by using HTTR.
Ooka, Yasunori*; Tanaka, Hideki*; Yamasaki, Masatoshi*; Goto, Minoru; Ueta, Shohei; Takagi, Naoyuki*; Katayama, Masaharu*
no journal, ,
The usage of thorium as nuclear fuel has been focused, which is produced with mining rare metal. The study on thorium fuel utilization is conducted for high temperature gas-cooled reactor (HTGR). We reported about the evaluations on the nuclear characteristics and on manufacturing of the thorium fuel for irradiation test using the High Temperature engineering Test Reactor (HTTR).
Shinohara, Masanori; Shibata, Taiju; Katayama, Masaharu*; Takagi, Naoyuki*; Ooka, Yasunori*; Yamasaki, Masatoshi*
no journal, ,
no abstracts in English
Goto, Minoru; Ueta, Shohei; Katayama, Masaharu*; Takagi, Naoyuki*; Ooka, Yasunori*; Yamasaki, Masatoshi*
no journal, ,
To utilize thorium in a high temperature gas-cooled reactor (HTGR), calculation of its nuclear characteristics with high accuracy is important subject. Criticality, which is one of the important nuclear characteristics, was measured for thorium loaded core by using critical assemblies, and comparisons between the measurements and calculations were reported. While measurement of criticality of thorium loaded core using actual reactor is almost not published. This paper described about measurement of nuclear characteristics of thorium loaded core using a High Temperature Engineering Test Reactor (HTTR).
Katayama, Masaharu*; Takamatsu, Kuniyoshi; Sawa, Kazuhiro; Takagi, Naoyuki*; Ooka, Yasunori*; Yamasaki, Masatoshi*
no journal, ,
no abstracts in English
Ueta, Shohei; Goto, Minoru; Katayama, Masaharu*; Takagi, Naoyuki*; Ooka, Yasunori*; Yamasaki, Masatoshi*
no journal, ,
For the feasibility study on a wide-variety of fuel utilization of the high temperature gas-cooled reactor (HTGR) in order to confirm the integrity and the irradiation performance of thorium as the fuel, the irradiation test with thorium-uranium mixed dioxide fuel (denoted as thorium fuel) by the High temperature engineering test reactor (HTTR) of Japan Atomic Energy Agency (JAEA) has been reviewed, and its neutronic characteristics has been evaluated. With regard to the license, the HTTR and the fuel fabrication plant of Nuclear Fuel Industries, Ltd. have been permitted to treat thorium as the fuel. During the irradiation, the integrity of the fuel specimen can be monitored continuously by the fuel failure detection (FFD) system installed in the HTTR. After the irradiation, the fuel sample is dismantled from the core and post-irradiation examinations are carried out to confirm the integrity and to evaluate the irradiance of the test fuel. The irradiance of the thorium fuel sample have been estimated in case of the irradiation test with three block of the thorium fuel in 4 of thorium to uranium mixed ratio and in 20% of enrichment of uranium-235. As the result, the burnup of the thorium fuel specimens will be approximately 21 GWd/t with 30 MW of reactor power in 660 days of the irradiation duration.
Wakui, Takashi; Yamasaki, Kazuhiko*; Futakawa, Masatoshi
no journal, ,
Pulsed Nd:YAG laser was irradiated to two radiation shielding glasses with the different lead content and a lead-free glass. Although no irradiation damage of the lead-free glass was visually confirmed in the laser irradiation condition of this study, the irradiation damage in the lead glasses could be recognized and the lead glass with the high lead content tends to cause the higher irradiation damage. Vickers hardness, elastic modulus and fracture toughness were evaluated by indentation technique with a Vickers indenter were 82-75%, 90-80% and 71-65% of the lead-free glass, respectively. The yield stresses evaluated by the inverse analysis using Kalman's filter based on load-depth curve obtained by the indentation technique with a spherical indenter were 87-67% of the lead-free glass. The yield stress of the irradiation damage area of the lead glass with the low lead content decreased to 74% of unirradiated area.
Wakui, Takashi; Saito, Shigeru; Yamasaki, Kazuhiko*; Sakai, Tomoki*; Mori, Kotaro*; Futakawa, Masatoshi
no journal, ,
Irradiation damage due to protons and neutrons reduces ductility in the mercury target vessel of J-PARC. The radiation damage is one of the factors that determine the lifetime. The evaluation of the irradiation damage is extremely important for long-term operation at high beam power. A simple and rapid indentation technique is investigated in order to evaluate mechanical properties. Ion irradiation is a technique for simulating radiation damage, but the damage area is limited to the very surface layer. Therefore, we propose a mechanical property evaluation technique using an inverse analysis combining a Kalman filter and numerical experiments to the load-depth curve. As a result, changes in the mechanical properties due to ion irradiation were detected and it was confirmed that this evaluation technique was very effectiveness. In addition, the technique was applied to lead glass, and it was clarified that the microplastic behavior of glasses can be evaluated quantitatively.
