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Torikawa, Tomoaki*; Odaira, Naoya*; Ito, Daisuke*; Ito, Kei*; Saito, Yasushi*; Matsushita, Kentaro; Ezure, Toshiki; Tanaka, Masaaki
Konsoryu, 36(1), p.63 - 69, 2022/03
On free surface of a sodium cooled fast reactor, gas entrainment can be caused by free surface vortices, which may result in disturbance in core power. It is important to develop an evaluation model to predict accurately entrained gas flow rate. In this study, entrained gas flow rate a simple gas entrainment experiment is conducted with focusing on effect of pressure difference between upper and lower tanks. Pressure difference between upper and lower tanks are controlled by changing gas pressure in lower tank. As a result, it is confirmed that the entrained gas flow rate increases with increasing pressure difference between upper and lower tanks. By visualization of swirling annular flow in suction pipe, it is also observed that pressure drop in suction pipe increases with increase in entrained gas flow rate, which implies that entrained gas flow rate can be predicted by evaluation model based on pressure drop in swirling annular flow region.
Tanaka, Sota; Kinouchi, Tadatoshi*; Fujii, Tsuguru*; Imanaka, Tetsuji*; Takahashi, Tomoyuki*; Fukutani, Satoshi*; Maki, Daisuke*; Notomi, Akihiro*; Takahashi, Sentaro*
Scientific Reports (Internet), 10, p.16055_1 - 16055_7, 2020/09
Times Cited Count:7 Percentile:49.75(Multidisciplinary Sciences)Since the Fukushima Dai-ichi Nuclear Power Plant (FDNPP) accident, morphological abnormalities of the lepidopteran insects have been reported. However, it is unclear whether the abnormalities were caused directly by radiation because they did not study on absorbed dose and dose-effect relationship. In this study, we conducted an internal exposure experiment on silkworm using CsCl-supplemented artificial diet and estimated the absorbed dose to evaluate the morphological abnormalities in silkworm. The ratio of wing to whole body of pupae was compared between the CsCl-exposured and control groups and no significant differences were observed between the groups. This result suggest that morphological abnormalities in lepidopterans are unlikely due to direct radiation effects from Cs contamination after the FDNPP accident.
Ito, Kei*; Ito, Daisuke*; Saito, Yasushi*; Ezure, Toshiki; Matsushita, Kentaro; Tanaka, Masaaki; Imai, Yasutomo*
Proceedings of 18th International Topical Meeting on Nuclear Reactor Thermal Hydraulics (NURETH-18) (USB Flash Drive), p.6632 - 6642, 2019/08
In this paper, a mechanistic model is proposed to calculate the entrained gas flow rate by a free surface vortex. The model contains the theoretical equation of transient gas core elongation and the empirical equation of critical gas core length for gas bubble detachment. Based on those two equations, the entrained gas flow rate is calculated as the portion of the gas core elongated beyond the critical gas core length per unit time. Then, the mechanistic model was applied to the calculation of the entrained gas flow rate in a simple water experiment. As a result, it is confirmed that the entrained gas flow rate grows rapidly when the liquid (water) flow rate, which determine the strength of a free surface vortex, exceeds a certain threshold value.
Strasser, P.*; Abe, Mitsushi*; Aoki, Masaharu*; Choi, S.*; Fukao, Yoshinori*; Higashi, Yoshitaka*; Higuchi, Takashi*; Iinuma, Hiromi*; Ikedo, Yutaka*; Ishida, Katsuhiko*; et al.
EPJ Web of Conferences, 198, p.00003_1 - 00003_8, 2019/01
Times Cited Count:13 Percentile:99.06(Quantum Science & Technology)Strasser, P.*; Aoki, Masaharu*; Fukao, Yoshinori*; Higashi, Yoshitaka*; Higuchi, Takashi*; Iinuma, Hiromi*; Ikedo, Yutaka*; Ishida, Katsuhiko*; Ito, Takashi; Iwasaki, Masahiko*; et al.
Hyperfine Interactions, 237(1), p.124_1 - 124_9, 2016/12
Times Cited Count:7 Percentile:90.97(Physics, Atomic, Molecular & Chemical)Nakayama, Masashi; Amano, Kenji; Tokiwa, Tetsuya; Yamamoto, Yoichi; Oyama, Takuya; Amano, Yuki; Murakami, Hiroaki; Inagaki, Daisuke; Tsusaka, Kimikazu; Kondo, Keiji; et al.
JAEA-Review 2012-035, 63 Pages, 2012/09
The Horonobe Underground Research Laboratory Project is planned to extend over a period 20 years. The investigations will be conducted in three phases, namely "Phase 1: Surface-based investigations", "Phase 2: Construction Phase" (investigations during construction of the underground facilities) and "Phase 3: Operation phase"(research in the underground facilities). This report summarizes the results of the investigations for the 2011 fiscal year (2011/2012). The investigations, which are composed of "Geoscientific research" and "R&D on geological disposal technology", were carried out according to "Horonobe Underground Research Laboratory Project Investigation Program for the 2011 Fiscal year". The results of these investigations, along with the results which were obtained in other departments of Japan Atomic Energy Agency (JAEA), are properly offered to the implementations and the safety regulations. For the sake of this, JAEA has proceeded with the project in collaboration with experts from domestic and overseas research organisations.
Horikawa, Daiki*; Yamaguchi, Ayami*; Sakashita, Tetsuya; Tanaka, Daisuke*; Hamada, Nobuyuki*; Yukuhiro, Fumiko*; Kuwahara, Hirokazu*; Kunieda, Takekazu*; Watanabe, Masahiko*; Nakahara, Yuichi*; et al.
Astrobiology, 12(4), p.283 - 289, 2012/04
Times Cited Count:23 Percentile:68.76(Astronomy & Astrophysics)We examined the hatchability of hydrated and anhydrobiotic eggs of the tardigrade to hatch after ionizing irradiation (helium ions), extremely low and high temperatures, and high vacuum. Anhydrobiotic eggs (50% lethal dose; 1690 Gy) were substantially more radioresistant than hydrated ones (50% lethal dose; 509 Gy). Anhydrobiotic eggs also have a broader temperature resistance compared with hydrated ones. Over 70% of the anhydrobiotic eggs treated at high and low temperatures, but all of the hydrated eggs failed to hatch. After exposure to high vacuum conditions, the hatchability of the anhydrobiotic eggs was comparable to that of untreated control eggs.
Kiriyama, Hiromitsu; Mori, Michiaki; Nakai, Yoshiki*; Shimomura, Takuya; Sasao, Hajime*; Tanaka, Momoko; Ochi, Yoshihiro; Tanoue, Manabu*; Kondo, Shuji; Kanazawa, Shuhei; et al.
Reza Kenkyu, 38(9), p.669 - 675, 2010/09
This paper reviews the temporal contrast and spatial beam quality improvement techniques in a high intensity Ti:sapphire laser system that is based on chirped-pulse amplification (CPA). We describe a low gain optical parametric chirped-pulse amplification (OPCPA) preamplifier that uses high energy, clean pulse seeding and is shown to significantly improve the contrast to better than 10-10 relative to the peak of the main femtosecond pulse. We also report the use of a diffractive optical element for beam homogenization of a 100 J level Nd:glass green pump laser, achieving a flat-topped spatial profile with a filling factor near 80 %.
Kiriyama, Hiromitsu; Mori, Michiaki; Nakai, Yoshiki; Shimomura, Takuya; Sasao, Hajime; Tanaka, Momoko; Ochi, Yoshihiro; Tanoue, Manabu*; Okada, Hajime; Kondo, Shuji; et al.
JAEA-Conf 2010-002, p.18 - 21, 2010/06
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 (without pumping the booster amplifier) we found that the temporal contrast in this system exceeds 10 on the sub-nanosecond timescale, and is near 10 on the 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.
Kiriyama, Hiromitsu; Mori, Michiaki; Nakai, Yoshiki; Shimomura, Takuya; Sasao, Hajime; Tanaka, Momoko; Ochi, Yoshihiro; Tanoue, Manabu*; Okada, Hajime; Kondo, Shuji; et al.
Applied Optics, 49(11), p.2105 - 2115, 2010/04
Times Cited Count:39 Percentile:83.7(Optics)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 compressed pulse without pumping the final amplifier we found that the temporal contrast in this system exceeds 10 on the sub-nanosecond timescales, and is near 10 on the nanosecond timescale prior to the peak of 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 a near-perfect top-hat-like intensity distribution.
Kiriyama, Hiromitsu; Mori, Michiaki; Nakai, Yoshiki; Shimomura, Takuya*; Tanoue, Manabu*; Okada, Hajime; Sasao, Hajime; Wakai, Daisuke*; Kondo, Shuji; Kanazawa, Shuhei; et al.
JAEA-Conf 2009-007, p.97 - 100, 2010/03
no abstracts in English
Kiriyama, Hiromitsu; Mori, Michiaki; Nakai, Yoshiki; Shimomura, Takuya; Tanoue, Manabu*; Okada, Hajime; Kondo, Shuji; Kanazawa, Shuhei; Sagisaka, Akito; Daito, Izuru; et al.
AIP Conference Proceedings 1153, p.3 - 6, 2009/07
We demonstrate a high-contrast, high-intensity double chirped-pulse amplification (CPA) Ti:sapphire laser system using an optical parametric chirped-pulse amplifier (OPCPA) as a preamplifier. By injecting cleaned microjoule seed pulses into the OPCPA, a temporal contrast greater than 10 within picosecond times before the main femtosecond pulse is demonstrated with the output pulse energy of 1.7 J and pulse duration of 30 fs, corresponding to a peak power of 60 TW at a 10 Hz repetition rate. This system uses a cryogenically-cooled Ti:sapphire final amplifier and generates focused peak intensities in excess of 10 W/cm.
Otsuka, Ichiro; Taki, Hiroshi*; Yamaguchi, Tetsuji; Iida, Yoshihisa; Yamada, Fumika; Inada, Daisuke*; Tanaka, Tadao
JAEA-Research 2008-043, 101 Pages, 2008/03
The influence of carbon steel overpack corrosion on redox potential (h) of bentonite pore water under geological disposal environment was investigated. The thermodynamics data of corrosion products, the corrosion rate of carbon steel, and the information on cathode reactions were acquired by experiments and literature survey. We conducted preliminary analysis of h, ascertained the validity of Phreeq C and identified important points on the analysis. Results were summarized as follows. (1) Thermodynamic data of Fe, FeOH, Fe(OH)(aq), Fe(OH), Fe(OH), Fe, FeS(pyrite), FeCO(siderite),Fe(OH)(s), FeO(magnetite), Fe(cr) were determined by literature survey. The solubility product of FeCO(OH) was determined experimentally, and thermodynamic data were estimated. (2) The corrosion rate of carbon steel was obtained as a function of pH and sulfide ion concentration. (3) After corrosion tests of carbon steel, no CH, HS and HS, the reduction product of CO and SO,were not detected in liquid and gas phases. (4) Preliminary analysis showed that the redox couple changed as HS(aq)/SO, CH(aq)/CO, H(aq)/HO during the evaluation period. After 1000 years, h attained about -500 to -600 mV (vs. NHE) or -750 mV controlled by CH(aq)/CO,or H(aq)/HO, respectively.
Iida, Yoshihisa; Yamaguchi, Tetsuji; Inada, Daisuke; Tanaka, Tadao; Otsuka, Ichiro*
no journal, ,
no abstracts in English
Kiriyama, Hiromitsu; Mori, Michiaki; Nakai, Yoshiki; Shimomura, Takuya; Tanoue, Manabu*; Okada, Hajime; Kondo, Shuji; Kanazawa, Shuhei; Sagisaka, Akito; Daito, Izuru; et al.
no journal, ,
We demonstrated laser peak intensity above 10W/cm and temporal contrast exceeding 10 at a 10 Hz repetition rate with a 60 TW, 30 fs laser (J-KAREN laser). Here we report the upgrade of the J-KAREN laser to the petawatt peak power level. This is accomplished by adding a Ti:sapphire booster amplifier downstream of the final amplifier chain of the 60 TW J-KAREN laser system. Stretched pulses of energy 3 J from the previous J-KAREN laser are up-collimated and introduced into the final booster amplifier. The booster amplifier consists of a large-aperture Ti:sapphire crystal pumped by a frequency-doubled Nd:silicate glass laser with pulse energy 60 J. Diffractive optical elements are used for pump beam homogenization to maintain a uniform spatial profile and reliable, damage-free operation. The system produces an uncompressed output pulse energy exceeding 30 J with a near homogeneous flat-top spatial distribution, indicating potential peak power of 500 TW.
Kiriyama, Hiromitsu; Mori, Michiaki; Nakai, Yoshiki; Shimomura, Takuya; Tanoue, Manabu*; Okada, Hajime; Kondo, Shuji; Kanazawa, Shuhei; Sagisaka, Akito; Daito, Izuru; et al.
no journal, ,
We have demonstrated over 30 J broadband output energy based on optical parametric chirped-pulse amplification (OPCPA) and Ti:sapphire chirped-pulse amplification (CPA), indicating potential for peak power of 500 TW with extremely high temporal contrast.
Kiriyama, Hiromitsu; Mori, Michiaki; Nakai, Yoshiki; Shimomura, Takuya; Sasao, Hajime; Tanaka, Momoko; Ochi, Yoshihiro; Tanoue, Manabu*; Okada, Hajime; Kondo, Shuji; 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.
Kiriyama, Hiromitsu; Mori, Michiaki; Nakai, Yoshiki; Shimomura, Takuya; Sasao, Hajime; Tanaka, Momoko; Ochi, Yoshihiro; Tanoue, Manabu*; Okada, Hajime; Kondo, Shuji; 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.
Kiriyama, Hiromitsu; Mori, Michiaki; Nakai, Yoshiki*; Shimomura, Takuya; Sasao, Hajime; Tanaka, Momoko; Ochi, Yoshihiro; Tanoue, Manabu*; Okada, Hajime; Kanazawa, Shuhei; et al.
no journal, ,
We report the demonstration of over 30-J of uncompressed broadband energy, indicating the potential peak power in excess of 500-TW with high temporal-contrast around 10 and a flat-toped spatial-profile with an 80 percent filling factor.
Kiriyama, Hiromitsu; Mori, Michiaki; Nakai, Yoshiki*; Shimomura, Takuya; Sasao, Hajime*; Tanaka, Momoko; Ochi, Yoshihiro; Tanoue, Manabu*; Okada, Hajime; Kanazawa, Shuhei; et al.
no journal, ,
OPCPA (Optical parametric chirped-pulse amplification) operation with low gain by seeding with high energy, clean pulses is shown to significantly improve the contrast to better than 10-10 in a high intensity Ti:sapphire laser system that is based on chirped pulse amplification. In addition to the high contrast broadband high energy output from the final amplifier is achieved with a flat-topped spatial profile of filling factor near 77 %. This is the result of pump beam spatial profile homogenization with diffractive optical elements. Final pulse energies exceed 30 Joules indicating capability for reaching peak powers in excess of 500-TW.