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Journal Articles

Termination of electron acceleration in thundercloud by intracloud/intercloud discharge

Wada, Yuki*; Bowers, G. S.*; Enoto, Teruaki*; Kamogawa, Masashi*; Nakamura, Yoshitaka*; Morimoto, Takeshi*; Smith, D.*; Furuta, Yoshihiro*; Nakazawa, Kazuhiro*; Yuasa, Takayuki*; et al.

Geophysical Research Letters, 45(11), p.5700 - 5707, 2018/06

 Times Cited Count:16 Percentile:79.35(Geosciences, Multidisciplinary)

Journal Articles

Feasibility study of advanced measurement technology for solution monitoring at reprocessing plant; Dose rate measurement for the solution including Pu with FP

Matsuki, Takuya; Yamanaka, Atsushi; Sekine, Megumi; Suzuki, Satoshi*; Yasuda, Takeshi; Tsutagi, Koichi; Tomikawa, Hirofumi; Nakamura, Hironobu; LaFleur, A. M.*; Browne, M. C.*

Proceedings of INMM 58th Annual Meeting (Internet), 8 Pages, 2017/07

The Tokai Reprocessing Plant (TRP) has been developing a new detector from 2015 to 2017 for purpose to monitor Pu amount in High Active Liquid Waste (HALW) containing FP. It can make a contribution to an advanced approach to effectively and efficiently conduct safeguards for reprocessing facilities because it becomes available to monitor and verify nuclear material movement continuously by a new detector, which has proposed by IAEA. For the second step of this project, we conducted dose rate measurement on the guide rail installing in the cell storing the HALW tank and comparison between measured dose rate distribution and calculation result by MCNP simulation in order to investigate the dose rate distribution which is needed for shielding design of a new detector that is used for radiation (neutron/$$gamma$$ spectrum) measurement in the cell and inquest on the monitoring position of the detector for Pu monitoring. In this paper, we report the result of the dose rate measurement in the cell, improvement of the simulation model which is cleared by comparison between measurement result and calculation result and our future plan.

Journal Articles

Feasibility study of advanced technology for Pu with FP solution monitoring; Overview of research plan and modelling for simulation

Sekine, Megumi; Matsuki, Takuya; Suzuki, Satoshi; Tanigawa, Masafumi; Yasuda, Takeshi; Yamanaka, Atsushi; Tsutagi, Koichi; Nakamura, Hironobu; Tomikawa, Hirofumi; LaFleur, A. M.*; et al.

EUR-28795-EN (Internet), p.788 - 796, 2017/00

The IAEA has proposed in its long-term R&D plan, the development of technology to enable real-time flow measurement of nuclear material as a part of an advanced approach to effective and efficient safeguards for reprocessing facilities. To address this, JAEA has designed and developed a neutron coincidence based nondestructive assay system to monitor Pu directly in solutions which is after purification process and contains very little fission products (FPs). A new detector to enable monitoring of Pu in solutions with numerous FPs is being developed as a joint research program with U.S. DOE at the High Active Liquid Waste (HALW) Storage Facility in Tokai Reprocessing Plant. As the first step, the design information of HALW tank was investigated and samples of HALW was taken and analyzed for Pu concentration and isotope composition, density, content of dominant nuclides emitting $$gamma$$ ray or neutron, etc. in order to develop a Monte Carlo N-Particle Transport Code (MCNP) of the HALW tank. In addition, $$gamma$$ ray source spectra simulated by Particle and Heavy Ion Transport code System (PHITS) was developed by extracting peaks from the analysis data with germanium detector. These outputs are used for the fundamental data in the MCNP model which is then used to evaluate the type of detector, shielding design and measurement positions. In order to evaluate available radiations to measure outside the cell wall, continuous $$gamma$$ ray and neutron measurement were carried out and the results were compared to the simulation results. The measurement results showed that there are no FP peaks above 3 MeV. This paper presents an overview of the research plan, characteristics of HALW, development of source term for MCNP, simulation of radiation dose from the HALW tank and radiation measurement results at outside of cell wall.

Oral presentation

Carbon-14 measurements of PM$$_{2.5}$$ from Noto peninsular in Kanazawa, Japan

Yamada, Reina*; Ikemori, Fumikazu*; Nakamura, Toshio*; Minami, Masayo*; Watanabe, Takahiro; Kinouchi, Kento*; Matsuki, Atsushi*

no journal, , 

PM$$_{2.5}$$ is becoming the focus of international attention, particularly in eastern Asia, because of air pollution and the health risks. Carbon is one of the major components in aerosol. Therefore, sources of the carbon compound should be known for the understanding material cycles and mechanism of the rise. Radiocarbon analysis is unique and useful techniques for estimation of carbon sources in environmental samples including aerosol. Hence half-life of radiocarbon is 5730 years, percent modern carbon (pMC) value based on radiocarbon concentration of fossil fuels are negligible. Therefore, pMC value can reveal the components of carbon in aerosol (biomass carbon versus fossil fuel). In this study, aerosol samples were taken at Noto Peninsula in Ishikawa pref., Japan, in order to estimate contribution rate of biomass carbon and/or fossil fuel in PM$$_{2.5}$$. The pMC values of PM$$_{2.5}$$ at Noto were more than 70 in the summer of 2014. These results show that biomass contribution is relative high in the area.

Oral presentation

Source apportionment of carbonaceous matter in PM$$_{2.5}$$ at NOTO peninsula using $$^{14}$$C analysis

Yamada, Reina*; Ikemori, Fumikazu*; Nakamura, Toshio*; Minami, Masayo*; Watanabe, Takahiro; Kinouchi, Kento*; Matsuki, Atsushi*

no journal, , 

Aerosols and clouds seeded by them both affect the heat budget of the Earth, but their RF (radiative forcing) still involves large uncertainty (IPCC 2013). One of the least understood properties of aerosols is the source and contribution of the organics. Our recent observation revealed that submicron aerosol particles in Noto peninsula also have a relatively high concentration (approximately more than 50%) of carbonaceous matter throughout the year. It is difficult to presume its sources specifying its chemical species in many scenes because of its great variety. However, we can presume its source by using carbon isotope ratio. We conducted sampling in NOTOGRO (NOTO ground-based research observatory), lying at the edge of Noto peninsula, from 26th Jun to 23rd July, 2014. We corrected PM$$_{2.5}$$ using high volume air sampler for every week. Flow rate was 700L/min, and quartz fiber filter was used for sampling. $$^{14}$$C was analyzed using AMS $$^{14}$$C system (High Voltage Engineering Europe, Model 4130-AMS) and $$^{13}$$C using IRMS (isotope ratio mass spectrometer) in Nagoya University. As a result, it was found that 4 samples collected from 26th Jun to 23rd July had approximately 70 percent modern carbon (pMC). This result shows that modern plant (and/or biomass burning) activities mainly contribute to the submicron organic particle concentration in Noto peninsula.

Oral presentation

Feasibility study of Pu monitoring technology for Pu solution with FP; Optimization of $$gamma$$ rays measurement at the inside of the concrete cell

Suzuki, Satoshi; Sekine, Megumi; Matsuki, Takuya; Yamanaka, Atsushi; Nakamura, Hironobu; Tomikawa, Hirofumi

no journal, , 

From a viewpoint of effective and efficient safeguards, JAEA has started to develop a new technology using non-destructive assay to measure and monitor Pu solution with fission products stored at reprocessing facility since JFY 2015. In JFY 2016, we are planning to measure $$gamma$$ rays and neutron emitted from high radioactive liquid waste (HALW) tank at the inside of the concrete cell and consider whether it has a relationship with Pu amount. In this poster presentation, the detector selection to measure high dose rate at the inside of the concrete cell, optimization of detector system by shielding material and measurement place to prevent high dead time, and the thruster optimization to insert using penetration pipe through the 1.7 m thickness concrete wall are presented as an evaluation of radiation from HALW at Tokai Reprocessing Facility. This project has been carried out under the support of the Ministry of Education, Culture, Sports, Science and Technology (MEXT) of the Japanese government.

Oral presentation

Feasibility study of Pu monitoring technology for Pu solution with FP; Evaluation of $$gamma$$ rays spectrum by simulation at the concrete cell

Sekine, Megumi; Matsuki, Takuya; Yamanaka, Atsushi; Nakamura, Hironobu; Tomikawa, Hirofumi

no journal, , 

Plutonium (Pu) solution and solid waste containing fission products (FP) are stored in a reprocessing plant as inventory or retained waste. It is difficult to access the Pu solution with FP since it has an extremely high radiation dose rate, and there is no direct Pu solution continuous monitoring /verification technology. From a viewpoint of ensuring nuclear transparency, Japan Atomic Energy Agency (JAEA) has started to develop a new technology using non-destructive assay to measure and monitor Pu solution with FP since JFY 2015. In this poster presentation, model of storage tank/concrete cell for high radioactive liquid waste (HALW), and evaluation of $$gamma$$ ray spectra and the distribution of radiation dose rate based on actual HALW analysis results are presented. This project has been carried out under the support of the Ministry of Education, Culture, Sports, Science and Technology (MEXT) of the Japanese government.

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