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Takano, Kazuya; Oki, Shigeo; Ozawa, Takayuki; Yamano, Hidemasa; Kubo, Shigenobu; Ogura, Masashi*; Yamada, Yumi*; Koyama, Kazuya*; Kurita, Koichi*; Costes, L.*; et al.
EPJ Nuclear Sciences & Technologies (Internet), 8, p.35_1 - 35_9, 2022/12
The France and Japan teams have carried out collaborative works to have common technical views regarding a sodium-cooled fast reactor concept. Japan has studied the feasibility of an enhanced high burnup low-void effect (CFV) core and fuel using oxide dispersion-strengthened steel cladding in ASTRID 600. Regarding passive shutdown capabilities, Japan team has performed a preliminary numerical analysis for ASTRID 600 using a complementary safety device, called a self-actuated shutdown system (SASS), one of the safety approaches of Japan. The mitigation measures of ASTRID 600 against a severe accident, such as a core catcher, molten corium discharge assembly, and the sodium void reactivity features of the CFV core, are promising to achieve in-vessel retention for both countries. The common design concept based on ASTRID 600 is feasible to demonstrate the SFR core and safety technologies for both countries.
Ogura, Koya*; Hosoda, Masahiro*; Tamakuma, Yuki*; Suzuki, Takahito*; Yamada, Ryohei; Negemi, Ryoju*; Tsujiguchi, Takakiyo*; Yamaguchi, Masaru*; Shiroma, Yoshitaka*; Iwaoka, Kazuki*; et al.
International Journal of Environmental Research and Public Health, 18(3), p.978_1 - 978_16, 2021/02
Times Cited Count：8 Percentile：57.43(Environmental Sciences)Heged
s, M.*; Shiroma, Yoshitaka*; Iwaoka, Kazuki*; Hosoda, Masahiro*; Suzuki, Takahito*; Tamakuma, Yuki*; Yamada, Ryohei; Tsujiguchi, Takakiyo*; Yamaguchi, Masaru*; Ogura, Koya*; et al.
Journal of Radioanalytical and Nuclear Chemistry, 323(1), p.197 - 204, 2020/01
Times Cited Count：3 Percentile：27.87(Chemistry, Analytical)The radioactivity of cesium in the water and sediments of two major rivers was measured along with airborne radioactivity in Namie Town, after the recent partial lift on the evacuation order in 2017. The observed concentrations were up to 384 
11 mBq/L for 
Cs in unfiltered water and 1.28 0.09 mBq/m
for Cs in air, while the sediment had a maximum of 44900 23.4 Bq/kg for Cs. The 
Cs/Cs ratios indicate the main origin of the cesium in the sediment to be Unit 1 in good agreement with previous reports on the accident.
Kiriyama, Hiromitsu; Mori, Michiaki; Suzuki, Masayuki*; Daito, Izuru*; Okada, Hajime; Ochi, Yoshihiro; Tanaka, Momoko; Sato, Masatoshi*; Tamaoki, Yoshinori*; Yoshii, Takehiro*; et al.
Reza Kenkyu, 42(6), p.441 - 447, 2014/06
We describe three specific high power laser systems that are being developed in our laboratory for many applications in high field science, nonlinear optics and material processing. We report on a femtosecond petawatt-class Ti:sapphire chirped-pulse amplification laser system that can produce a pulse energy of 20 J of 40 fs pulse duration, a picosecond high intensity Yb:YAG chirped-pulse amplification laser system that can generate a pulse energy of 100 mJ of 0.5 ps pulse duration, and a nanosecond high repetition rate Nd:YAG laser system that can provide an average power of 360 W with a pulse duration of 30 ns delivered at a 1 kHz repetition rate. We discuss the basic design aspects and present the results from our experimental investigations of these laser systems.
Yogo, Akifumi; Sato, Katsutoshi; Nishikino, Masaharu; Maeda, Takuya; Nishiuchi, Mamiko; Sakaki, Hironao; Hori, Toshihiko; Mori, Michiaki; Ogura, Koichi; Orimo, Satoshi; et al.
no journal, ,
no abstracts in English
Mori, Michiaki; Kotaki, Hideyuki; Kawase, Keigo; Hayashi, Yukio; Kando, Masaki; Ogura, Koichi; Kondo, Kiminori; Bulanov, S. V.; Nishimura, Hiroaki*; Yokoyama, Atsushi
no journal, ,
no abstracts in English
Koga, Yasuhiko*; Kaira, Kyoichi*; Yamada, Masanobu*; Dobashi, Kunio*; Matsuzaki, Shinichi*; Hisada, Takeshi*; Koka, Masashi; Yamada, Naoto; Sato, Takahiro; Yokoyama, Akihito; et al.
no journal, ,
Kiriyama, Hiromitsu; Mori, Michiaki; Shimomura, Takuya; Nakai, Yoshiki*; Tanoue, Manabu*; Sasao, Hajime*; Kondo, Shuji; Kanazawa, Shuhei; Ochi, Yoshihiro; Tanaka, Momoko; et al.
no journal, ,
We report on a femtosecond high-intensity OPCPA/Ti:sapphire hybrid laser system that produces more than 30 J broadband output energy, indicating the potential for achieving petawatt-class peak powers. High temporal-contrast of 10
to 10
has been obtained with a near-perfect flat-topped spatial-profile of filling factor 
80%. We also present a compact, high-intensity OPCPA/Yb:YAG hybrid laser system that generates 100 mJ output energy with a temporal contrast of better than 10
and good spatial beam quality.
Mori, Michiaki; Ogura, Koichi; Yogo, Akifumi; Nishiuchi, Mamiko; Kiriyama, Hiromitsu; Pirozhkov, A. S.; Sagisaka, Akito; Orimo, Satoshi; Tampo, Motonobu; Daito, Izuru; et al.
no journal, ,
no abstracts in English
Yogo, Akifumi; Nishiuchi, Mamiko; Sakaki, Hironao; Hori, Toshihiko; Sato, Katsutoshi; Nishikino, Masaharu; Maeda, Takuya; Mori, Michiaki; Ogura, Koichi; Orimo, Satoshi; et al.
no journal, ,
no abstracts in English
Kiriyama, Hiromitsu; Nagashima, Keisuke; Ochi, Yoshihiro; Mori, Michiaki; Tanaka, Momoko; Sasao, Fumitaka; Kosuge, Atsushi; Okada, Hajime; Kondo, Kiminori; Sagisaka, Akito; et al.
no journal, ,
We have developed a femtosecond high intensity laser system, which combines both Ti:sapphire chirped-pulse amplification (CPA) and optical parametric chirped-pulse amplification (OPCPA) techniques, that produces more than 30 J broadband output energy, indicating the potential for achieving peak powers in excess of 500 TW. With a cleaned high-energy seeded OPCPA preamplifier as a front-end in the system, for the final compressed pulse we found that the temporal contrast in this system exceeds 10
on the sub-nanosecond timescale before the main femtosecond pulse. Using diffractive optical elements for beam homogenization of 100-J level high-energy Nd:glass green pump laser in a Ti:sapphire final amplifier, we have successfully generated broadband high-energy output with near-perfect top-hat intensity distributions.
