Applicability evaluation of candidate technologies for nuclear material quantification in fuel debris at Fukushima Daiichi Nuclear Power Station; Passive neutron technique (Interim report)

Nagatani, Taketeru; Kosuge, Yoshihiro*; Shirato, Atsuhiko*; Sato, Takashi*; Shiromo, Hideo; Asano, Takashi

Proceedings of INMM 57th Annual Meeting (Internet), 10 Pages, 2016/07

Monte Carlo N-Particle eXtended (MCNPX) simulation for passive neutron measurement of fuel debris at Fukushima Daiichi Nuclear Power Plants

Nagatani, Taketeru; Nakajima, Shinji; Kosuge, Yoshihiro*; Shiromo, Hideo; Asano, Takashi

Proceedings of INMM 55th Annual Meeting (Internet), 10 Pages, 2014/07

Meltdown of the reactor cores of Units 1-3 occurred at Fukushima Daiichi Nuclear Power Plants (1F). Fuel debris at 1F contains minor actinides and fission products and neutron absorber. These materials make it difficult to quantify fertile nuclear materials in fuel debris by the conventional passive neutron technique. We consider that DDSI and PNAR which focused on fissile material are promising techniques to quantify the nuclear materials in the fuel debris. A concept of application of these techniques to fuel debris measurement was investigated and presented at the last INMM annual meeting. In order to evaluate the applicability of these techniques to fuel debris measurement, we investigated the neutron behavior in the fuel debris by using MCNPX simulation code. Because property of fuel debris is not clear, source term data used were prepared by referring TMI data. This paper provides results of MCNPX simulation for fuel debris measurement at 1F with passive neutron techniques.

Beam-line improvement and new experiment stations of KEK-IMSS slow-positron facility

Wada, Ken*; Mochizuki, Izumi*; Hyodo, Toshio*; Kosuge, Takashi*; Saito, Yuki*; Shidara, Tetsuo*; Osawa, Satoshi*; Ikeda, Mitsuo*; Shirakawa, Akihiro*; Furukawa, Kazuro*; et al.

no journal, , 

no abstracts in English

Development of nanosecond pulsed laser decontamination method, 2; In-situ time- and space-resolved detection of micro/nano dusts

Kosuge, Atsushi; Ando, Kota*; Nakajima, Takashi*

no journal, , 

Decommissioning generates a large amount of radioactive waste. Laser decontamination has been attracting attention in recent years as an efficient and safe method of decontamination. Since the micro- and nano-dust generated by laser decontamination is radioactive, it is also important to collect the scattered micro- and nano-dust. In this presentation, we report spatially resolved measurements of micro/nano dust particles by irradiating uncontaminated metal samples with highly repetitive nanosecond laser pulses. First, the shape and distribution of particles attached to several cover glasses placed in a hemispherical shape near the laser irradiation point were observed using a laser microscope. Next, laser scattering measurements of particles were performed using a collimated beam and a horizontally spread laser sheet.

Nanosecond pulsed laser decontamination of stainless steel; Spatial and temporal resolution measurement of dust particles

Kosuge, Atsushi; Yamamoto, Keisuke*; Ando, Kota*; Nakajima, Takashi*

no journal, , 

Decommissioning of nuclear reactors generates a large amount of radioactive waste. Laser decontamination methods have recently attracted attention as an efficient and safe method for decontaminating these wastes. Since the micro/nano dust generated during laser decontamination is radioactive, it is important to establish an efficient method for collecting the dust. In this study, an uncontaminated metal sample was irradiated with a nanosecond pulsed laser pulse, and the dependence of dust shape and particle velocity on pulse duration at a distance from the target was measured.

Recent developments and results of the KEK slow positron facility

Wada, Ken*; Mochizuki, Izumi*; Hyodo, Toshio*; Kosuge, Takashi*; Saito, Yuki*; Nigorikawa, Kazuyuki*; Shidara, Tetsuo*; Osawa, Satoshi*; Ikeda, Mitsuo*; Shirakawa, Akihiro*; et al.

no journal, , 

no abstracts in English

Characterization study of four candidate technologies for nuclear material quantification in fuel debris at Fukushima Daiichi Nuclear Power Station, 2; Numerical simulations for passive neutron technique

Nomi, Takayoshi; Nagatani, Taketeru; Kosuge, Yoshihiro*; Shiromo, Hideo; Asano, Takashi

no journal, , 

Characterization study of candidate technologies for nuclear material quantification in fuel debris at Fukushima Daiichi Nuclear Power Station, 2-2; Passive neutron technique

Nomi, Takayoshi; Nagatani, Taketeru; Kosuge, Yoshihiro*; Shiromo, Hideo; Asano, Takashi

no journal, , 

no abstracts in English

Development of nanosecond pulsed laser decontamination method, 2; Comparison of target removal rates using 100 W nanosecond/CW lasers

Kosuge, Atsushi; Yamamoto, Keisuke*; Nakajima, Takashi*

no journal, , 

A large amount of radioactive waste is generated when a nuclear reactor is decommissioned after its operating period has ended. Efficient decontamination of radioactive waste reduces the amount of waste and significantly lowers storage costs. Decontamination methods using pulsed lasers, which are capable of ablation removal with reduced thermal effects, have been attracting attention. We report on the results of irradiating metal samples with a 100 W MOPA-type nanosecond fiber laser, whose parameters can be freely changed, and measuring the amount of removal. The laser with the same power density was applied to the target, and the change in removal amount due to pulse duration and repetition frequency was measured and compared with a continuous wave laser.