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Shirafuji, Masaya; Hasegawa, Rie; Akutsu, Narumi*; Maruyama, Hajime; Miyaji, Noriko
Dai-44-Kai Nihon Kaku Busshitsu Kanri Gakkai Nenji Taikai Kaigi Rombunshu (Internet), 4 Pages, 2023/11
To maintain transparency in the use of nuclear materials in Japan, it is important for operators to appropriately respond to safeguards activities conducted by the IAEA/Japan. Failure to appropriately respond to these activities could have significant impacts, such as raising suspicion from the international community about the misuse of nuclear materials by not only the operators but also Japan. To appropriately respond to safeguards activities, JAEA has conducted some activities such as education on safeguards for all employees and case study activities for the employees engaged in responding to safeguards activities. This paper focused on case study activities that started in FY2022. In FY2022, we created documents based on scenarios with problems in safeguards responses in order to promote understanding among participants. We also conducted a questionnaire survey for participants, and we evaluated the result of the questionnaire. The evaluation results showed that the case study activities contributed to raising awareness of safeguards responses, although there were improvements. After making improvements, we are conducting these activities again in FY2023. Since case study activities are expected to be effective if carried out continuously, we plan to continue them in combination with other activities.
Xia, C.-J.*; Maruyama, Toshiki; Yasutake, Nobutoshi*; Tatsumi, Toshitaka*; Shen, H.*; Togashi, Hajime*
Physical Review D, 102(2), p.023031_1 - 023031_18, 2020/07
Times Cited Count：16 Percentile：74.34(Astronomy & Astrophysics)no abstracts in English
O
ceramic thin diskMaruyama, Momoko; Okada, Hajime; Ochi, Yoshihiro; Nagashima, Keisuke
Optics Express (Internet), 24(2), p.1685 - 1692, 2016/01
Times Cited Count：5 Percentile：30.58(Optics)We have developed a 1 kHz regenerative amplifier using an Yb:YO ceramic thin disk as the gain medium. Furthermore, the thermal conductivity and heat generation property of Yb: YO ceramic were investigated. In the developed regenerative amplifier, a laser beam is bounced off the thin disk six times in each round trip. The output energy is over 2 mJ, spectral bandwidth is 1.8 nm at FWHM, and pulse duration after pulse compression is 0.9 ps.
Okada, Hajime; Maruyama, Momoko; Ochi, Yoshihiro; Nagashima, Keisuke
JAEA-Technology 2015-029, 29 Pages, 2015/11
JAEA-Technology-2015-029.pdf:11.21MB
We develop high repetitive and short pulse laser system using Yb doped laser ceramics for future laser application of generating high power tera-hertz wave for experimental proof of isotope separation and generating a Laser-Compton Scattering 
-ray source for precise specific isotopes analysis. As these future laser applications needs very stable and high average power laser system, we develop thin disk laser system using Yb:YAG ceramics because of its large stored energy property and large thermal conductivity, which could avoid thermal induced effects and thermal fracture limitation due to large pumping power. A few hundred 
m thickness of thin disk laser material in laser amplifier needs multi pass optical components for enough absorption of pump power, the pumping profile and spot size on laser disk should be variable for required laser performance. We design multi pass pumping module for thin disk laser material which consists of commercial optical components and precise stages and also design doublet and triplet for various pumping profile and spot size, the laser oscillation power is evaluated with this pumping module.
Sotani, Hajime*; Maruyama, Toshiki; Tatsumi, Toshitaka*
Nuclear Physics A, 906, p.37 - 49, 2013/05
Times Cited Count：15 Percentile：68.29(Physics, Nuclear)Inside neutron stars, the hadron-quark mixed phase is expected during the first order phase transition from the hadron phase to the quark phase. The geometrical structure of the mixed phase strongly depends on the surface tension at the hadron-quark interface. We evaluate the shear modulus which is one of the specific properties of the hadron-quark mixed phase. As an application, we study shear oscillations due to the hadron-quark mixed phase in neutron stars. We find that the frequencies of shear oscillations depend strongly on the surface tension; with a fixed stellar mass, the fundamental frequencies are almost proportional to the surface tension. Thus, one can estimate the value of surface tension via the observation of stellar oscillations with the help of the information on the stellar mass.
Yasutake, Nobutoshi*; Noda, Tsuneo*; Sotani, Hajime*; Maruyama, Toshiki; Tatsumi, Toshitaka*
Recent Advances in Quarks Research, p.63 - 111, 2013/01
Nomi, Takayoshi; Nagatani, Taketeru; Ninagawa, Junichi; Nakajima, Shinji; Maruyama, Hajime; Asano, Takashi; Fujiwara, Shigeo
Kaku Busshitsu Kanri Gakkai (INMM) Nihon Shibu Dai-32-Kai Nenji Taikai Rombunshu (Internet), 8 Pages, 2011/11
The IS approach for the JNC-1 site was implemented in August 2008, and this was the first experience in the world. This IS approach aimed not only to improve efficiency and effectiveness of safeguards but also to reduce burden of the plant operation by improvement of efficiency of the inspection activity. It was planned to review effectiveness of this new approach after three years from implementation. And JAEA also evaluated effects by application of the IS approach for two MOX fuel facilities in the JNC-1 site based on the three years experiences from the operator's view point. As the result of evaluation, it was confirmed that there were some difference of benefits by application of the IS approach depending on features of the facility, automation level of equipment and advance level of safeguards systems.
Sotani, Hajime*; Yasutake, Nobutoshi*; Maruyama, Toshiki; Tatsumi, Toshitaka*
Physical Review D, 83(2), p.024014_1 - 024014_8, 2011/01
Times Cited Count：82 Percentile：93.39(Astronomy & Astrophysics)We calculate stellar oscillations including the hadron-quark mixed phase considering the finite size effects. We find that it is possible to distinguish whether the mixed phase exists or not in stars, even if one will observe the gravitational waves of the fundamental mode. Additionally, the normalized eigenfrequencies of pressure modes depend strongly on the stellar mass and on the adopted equation of state. Especially, in spite of the fact that the radius of the neutron star with 1.4 times the solar mass, which is standard mass, is almost independent from the equation of state with quark matter, the frequencies of pressure modes depend on the adopted equation of state. Thus, via observing the many kinds of gravitational waves, it will be possible to make a restriction on the equation of state.
Moriyama, Kiyofumi; Maruyama, Yu; Nakamura, Hideo; Hashimoto, Kazuichiro; Kamo, Hideki*; Onuki, Akira; Akimoto, Hajime
Dai-7-Kai Doryoku Enerugi Gijutsu Shimpojiumu Koen Rombunshu (00-11), p.451 - 456, 2000/11
no abstracts in English
Ninagawa, Junichi; Takahashi, Saburo; Asano, Takashi; Maruyama, Hajime; Kobayashi, Shigeru*
P.149, (105), p.21 - 25, 1998/03
None
Sotani, Hajime*; Yasutake, Nobutoshi*; Maruyama, Toshiki; Tatsumi, Toshitaka*
no journal, ,
no abstracts in English
Ochi, Yoshihiro; Nagashima, Keisuke; Maruyama, Momoko; Okada, Hajime; Sugiyama, Akira; Tateno, Ryo*; Furukawa, Yasuyuki*
no journal, ,
We designed and fabricated high resistant AR and HR coatings using AlO layer for Yb:YAG tin-disk amplifier. The damage threshold fluences for 520 ps pulse (AR, HR) and 1.2 ps pulse (HR only) were measured by uncompressed and compressed pulses, respectively, from the regenerative amplifier in QUADRA-T. As results, the damage threshold fluence of the AR coating of AlO/SiO multilayer was 75 J/cm
for 520 ps pulse. This is satisfied out target value 40 J/cm to use in the amplifiers. For the HR coating, the highest damage threshold fluences, 2.4 J/cm for 1.2 ps pulse and 123.6 J/cm for 520 ps pulse, respectively, were obtained by manipulating AlO/SiO layer thickness to set a point of the maximum electric field in the SiO layer.
Maruyama, Momoko; Okada, Hajime; Ochi, Yoshihiro; Nagashima, Keisuke; Sugiyama, Akira
no journal, ,
We used Yb:YO for a gain medium of regenerative amplifier of QUADRA-T laser system. The band width of 1.2 nm and pulse width of 1.3 ps are improved to be 1.8 nm and 0.9 ps.
Suzuki, Ryuta; Watanabe, Naoki; Minouchi, Hiroyuki; Maruyama, Hajime; Watahiki, Masatoshi
no journal, ,
Radioactive solid waste must be safely stored and managed for a long period of time until it is incinerated or otherwise processed at a treatment facility. To check the integrity of radioactive solid waste containers, visual inspection is periodically performed. However, since this inspection is conventionally performed by human eye, the information that can be obtained is limited. Therefore, we focused on a non-destructive inspection method using an infrared camera to detect corrosion on the inner surface of the containers that cannot be seen from the outer surface. To confirm the applicability of this new method, measurement tests using corroded mock-up containers were conducted, and the measurement results were summarized and evaluated.
