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Journal Articles

Nanosecond laser-induced coloration of radiation resistant lead glasses

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$$^{-1}$$ and 1000 cm$$^{-1}$$ in Raman spectrums.

Journal Articles

Development on laser cutting technique to suppress spatter particles aiming at disposal of radio-active waste

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.

Journal Articles

Three-dimensional microstructure and high temperature strength in ODS 9Cr ferritic heat resistant steels

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

Journal Articles

Development of a simple reprocessing process using selective precipitant for uranyl ions; Engineering studies on systems for precipitating and separating

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:25.79(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$$_{2}$$$$^{2+}$$-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.

Oral presentation

Development of a simple reprocessing process by selective precipitation for uranyl ions

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

Oral presentation

A Method of fabrication meso-nozzle for bubbling

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.

Oral presentation

Feasibility study on material creation and new-type fuel utilization by using HTTR, 1; Outline of feasibility study

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.

Oral presentation

Feasibility Study on material creation and new-type fuel utilization by using HTTR, 5; Study on thorium fuel utilization

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).

Oral presentation

Feasibility Study on material development and new-type fuel utilization by using HTTR, 4; Feasibility study on development of irradiation capsule and irradiation method

Shinohara, Masanori; Shibata, Taiju; Katayama, Masaharu*; Takagi, Naoyuki*; Ooka, Yasunori*; Yamasaki, Masatoshi*

no journal, , 

no abstracts in English

Oral presentation

Feasibility study on a wide-variety of fuel utilization by using HTTR, 3; Nuclear characteristics of thorium loaded core

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).

Oral presentation

Feasibility study on a wide-variety of fuel utilization by using HTTR, 1; Outline of feasibility study

Katayama, Masaharu*; Takamatsu, Kuniyoshi; Sawa, Kazuhiro; Takagi, Naoyuki*; Ooka, Yasunori*; Yamasaki, Masatoshi*

no journal, , 

no abstracts in English

Oral presentation

Feasibility study on a wide-variety of fuel utilization by using HTTR, 4; Study on thorium fuel utilization

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.

Oral presentation

Material properties degradation of radiation shielding lead glasses by laser irradiation

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.

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