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JAEA Reports

Development of measurement system of radioactive plume using unmanned airplane in the fiscal year 2017 (Contract research)

Sanada, Yukihisa; Nishizawa, Yukiyasu*; Ochi, Kotaro; Yuki, Yoichi*; Ishizaki, Azusa; Osada, Naoyuki*

JAEA-Research 2018-009, 48 Pages, 2019/01


At the accident of nuclear facilities, a prediction of the behavior of released radioactive plume is indispensable to make a decision on a refuge plan of inhabitants. Currently, prediction system which is based on atmospheric dispersion simulation has been implemented as a tool of the atomic energy disaster prevention. However, the direct measurement method of the radioactive plume has not existed. In this study, some component technologies were developed for the establishment of direct measurement methods of radioactive plume using unmanned aerial vehicle whose technological innovation is remarkable. In addition, the spray test using mock aerosol was conducted to obtaining the deposition rate to the airplane body. The algorism of making a flight plan was developed based on a prediction model of the radioactive plume. This report summarized the outcome of the second year of the three-year plan.

JAEA Reports

Radiation monitoring using manned helicopter around the Fukushima Daiichi Nuclear Power Station in the fiscal year 2014 (Contract research)

Sanada, Yukihisa; Mori, Airi; Ishizaki, Azusa; Munakata, Masahiro; Nakayama, Shinichi; Nishizawa, Yukiyasu; Urabe, Yoshimi; Nakanishi, Chika; Yamada, Tsutomu; Ishida, Mutsushi; et al.

JAEA-Research 2015-006, 81 Pages, 2015/07


By the nuclear disaster of Fukushima Daiichi Nuclear Power Station (NPS), Tokyo Electric Power Company (TEPCO), caused by the East Japan earthquake and the following tsunami occurred on March 11, 2011, a large amount of radioactive materials was released from the NPP. These results of the aerial radiation monitoring using the manned helicopter in the fiscal 2014 were summarized in the report.

Journal Articles

Probabilistic properties of measurement for thickness of pipe with metal loss

Kaida, Takuyo*; Ishizaki, Yoichi*; Okajima, Satoshi

Atsuryoku Gijutsu, 52(2), p.53 - 63, 2014/04

Probabilistic approach for Fitness-For-Service (FFS) assessment of pressure equipment in petroleum and petrochemical plant helps to quantify the safety margin and rationalize the assessment. As for local metal loss assessment, several studies have been made on reliability analysis of the damaged equipment by use of limit state function, denoted by deterministic FFS model in published standard. Stochastic properties of random variables are needed in the reliability analysis. Remaining thickness of the pressure equipment is one of the important variables in limit state function for metal loss assessment. The thickness readings on a prescribed grid, which characterize the remaining thickness and size of the region of metal loss, might be varied by each inspector. There has been, however, no studies on stochastic properties of thickness readings for the local metal loss assessment. In this study, the stochastic properties of thickness readings were investigated by analyzing of the results of Round-Robin test. The cause of variation of thickness readings was clarified for the purpose of either protection of failure by pressure or that of leakage. The results of investigation indicated that standard deviation of thickness readings in the region of metal loss was more than that of thickness away from metal loss. Finally, the reliability of pressure equipment with local metal loss was analyzed using stochastic properties.

JAEA Reports

Operation and management data for the JRR-3 CNS Facility

Suzuki, Masatoshi; Hazawa, Tomoya; Ishizaki, Yoichi*; Obara, Michio*; Inada, Katsutoshi*; Yonekawa, Mitsunori*; Wakita, Hiroshi*

JAERI-Tech 2004-060, 153 Pages, 2004/09


The cold neutron source (CNS) at JRR-3 was constructed for the purpose of improving the utilization performance of the reactor along the lines of upgrade program. There are two methods for extracting cold neutrons from a reactor, one is to filter a small fraction of cold neutrons in the Maxwellian spectrum of reactor neutrons while the other is to increase the fraction of cold neutron by inserting a cryogenic moderator. The latter is adopted as CNS facilities at almost all cases, and liquid hydrogen and its cooling system are equipped with a cold neutron source at many neutron facilities just like JRR-3. Cold neutrons generated in a cold source are extracted through a neutron guide tube, and are utilized for the purpose of neutron beam experiments such as neutron scattering which study the structures of atoms and molecules in the materials and life science fields. This report summarizes the operation data and the main technical issues which were recorded in the whole operation period from commencement date in 1989 to March 2004.

Oral presentation

Estimation of aerosol attachment to airplane flying in plume from nuclear power plant

Osada, Naoyuki*; Ishizaki, Azusa; Nishizawa, Yukiyasu*; Yuki, Yoichi*; Sanada, Yukihisa

no journal, , 

no abstracts in English

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