Core performance requirements and design conditions for next-generation sodium-cooled fast reactor in Japan

Oki, Shigeo; Maruyama, Shuhei; Chikazawa, Yoshitaka; Ohtaki, Akira; Kubo, Shigenobu; Hibi, Koki*; Kan, Taro*

Proceedings of 2017 International Congress on Advances in Nuclear Power Plants (ICAPP 2017) (CD-ROM), 9 Pages, 2017/04

Yb:YAG thin-disk chirped pulse amplification laser system for intense terahertz pulse generation

Ochi, Yoshihiro; Nagashima, Keisuke; Maruyama, Momoko; Tsubouchi, Masaaki; Yoshida, Fumiko; Kono, Nanase; Mori, Michiaki; Sugiyama, Akira

Optics Express (Internet), 23(11), p.15057 - 15064, 2015/06

https://doi.org/10.1364/OE.23.015057

We have developed a 1 kHz repetition picosecond laser system dedicated for intense terahertz (THz) pulse generation. The system comprises a chirped pulse amplification laser equipped with a Yb:YAG thin-disk amplifier. At room temperature, the Yb:YAG thin-disk regenerative amplifier provides pulses having energy of over 10 mJ and spectral bandwidth of 1.2 nm. The pulse duration achieved after passage through a diffraction grating pair compressor was 1.3 ps. By employing this picosecond laser as a pump source, THz pulses having a peak frequency of 0.3 THz and 4 J of energy were generated by means of optical rectification in an Mg-doped LiNbO crystal.

Neutron-coupled thermal hydraulic calculation of BWR under seismic acceleration

Satou, Akira; Watanabe, Tadashi; Maruyama, Yu; Nakamura, Hideo

Proceedings of Joint International Conference of 7th Supercomputing in Nuclear Application and 3rd Monte Carlo (SNA + MC 2010) (USB Flash Drive), 5 Pages, 2010/10

In the BWR subjected to an earthquake, the oscillating acceleration attribute to the seismic wave may cause the variation of the coolant flow rate and void fraction in the core, which might result in the core instability due to the void-reactivity feedback. Therefore, it is important to properly evaluate the effect of the seismic acceleration on the core stability from a viewpoint of plant integrity estimation. In the present study the numerical code analyzing the behavior of nuclear power plant under the seismic acceleration is developed based on the 3-D neutron-coupled thermal hydraulic code, TRAC/SKETCH. The coolant flow is simulated with introducing the acceleration attributed to the earthquake into the motion equation of the flow as external force terms. The analyses are performed on a real BWR4-type nuclear power plant with the sinusoidal acceleration and the acceleration obtained from the response analysis to an actual earthquake. The behaviors of the core and coolant are calculated in the various parameters of acceleration. The effects of the frequency, amplitude and direction of the oscillating acceleration are discussed.

Study on transient void behavior during reactivity initiated accidents under low pressure condition; Development and application of measurement technique for void fraction in bundle geometry

Satou, Akira; Maruyama, Yu; Asaka, Hideaki; Nakamura, Hideo

Proceedings of 14th International Conference on Nuclear Engineering (ICONE-14) (CD-ROM), 8 Pages, 2006/07

Series of out-of-pile experiments to obtain the knowledge on the transient void behavior during reactivity initiated accidents are in progress at JAEA. In the present series of experiments, the transient void behavior in a test section of 22 bundle geometry under atmospheric pressure condition was measured using an impedance technique. The measuring areas and the arrangement of electrodes for the impedance technique were defined on the basis of numerical analyses and scaled model experiments. The comparison was made between the impedance and differential pressure techniques for steady boiling experiments to estimate the accuracy of the impedance technique. The impedance technique showed a good agreement with the void fraction estimated from the differential pressure. The transient void behavior in the bundle geometry was measured using the impedance technique. It was clarified that the transient void behavior depends on both the subcooling of inlet water and the heat generation rate of simulated fuel rod. Local void fraction was influenced by the ratio of flow area to heat transfer area of the simulated fuel rod.

Sideward peak of intermediate mass fragments in high energy proton induced reactions

Hirata, Yuichi*; Onishi, Akira*; Nara, Yasushi*; Kido, Toshihiko; Maruyama, Toshiki; Otsuka, Naohiko*; Niita, Koji*; Takada, Hiroshi; Chiba, Satoshi

Nuclear Physics A, 707(1-2), p.193 - 212, 2002/08

https://doi.org/10.1016/S0375-9474(02)00747-9

no abstracts in English

Quantum molecular dynamics simulation of expanding nuclear matter and nuclear multifragmentation

Chikazumi, Shimpei*; Maruyama, Toshiki; Chiba, Satoshi; Niita, Koji*; Iwamoto, Akira

Physical Review C, 63(2), p.024602_1 - 024602_10, 2001/02

https://doi.org/10.1103/PhysRevC.63.024602

no abstracts in English

Development of fuel-coolant interaction analysis code

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

Efficient discharge pumping of a copper vapor laser using a cylindrical grid electrode

Ozu, Akira; Kato, Masaaki; Maruyama, Yoichiro

Review of Scientific Instruments, 71(6), p.2288 - 2291, 2000/06

https://doi.org/10.1063/1.1150443

no abstracts in English

Enhancement of ion extraction from a cold plasma with radio-frequency plasma heating

Ozu, Akira; Suzuki, Yoji; Maruyama, Yoichiro; Arisawa, Takashi

Applied Physics Letters, 76(14), p.1822 - 1824, 2000/04

https://doi.org/10.1063/1.126177

no abstracts in English

Growth of dendrites in a large bore HyBrID copper vapor laser

Ozu, Akira; Kato, Masaaki; Maruyama, Yoichiro

Optics & Laser Technology, 32(2), p.101 - 105, 2000/03

no abstracts in English