Annual report on the effluent control of low level liquid waste in Nuclear Fuel Cycle Engineering Laboratories FY2021

Nakada, Akira; Kanai, Katsuta; Kokubun, Yuji; Nagaoka, Mika; Koike, Yuko; Yamada, Ryohei*; Kubota, Tomohiro; Hirao, Moe; Yoshii, Hideki*; Otani, Kazunori*; et al.

JAEA-Review 2022-079, 116 Pages, 2023/03

JAEA-Review-2022-079.pdf:2.77MB

Based on the regulations (the safety regulation of Tokai Reprocessing Plant, the safety regulation of nuclear fuel material usage facilities, the radiation safety rule, the regulation about prevention from radiation hazards due to radioisotopes, which are related with the nuclear regulatory acts, the local agreement concerning with safety and environment conservation around nuclear facilities, the water pollution control law, and by law of Ibaraki Prefecture), the effluent control of liquid waste discharged from the Nuclear Fuel Cycle Engineering Laboratories of Japan Atomic Energy Agency has been performed. This report describes the effluent control results of the liquid waste in the fiscal year 2021. In this period, the concentrations and the quantities of the radioactivity in liquid waste discharged from the reprocessing plant, the plutonium fuel fabrication facilities, and the other nuclear fuel material usage facilities were much lower than the limits authorized by the above regulations.

Development of measurement system of radioactive plume using unmanned airplane in the fiscal year 2018 (Contract research)

Sanada, Yukihisa; Ochi, Kotaro; Ishizaki, Azusa

JAEA-Research 2020-006, 60 Pages, 2020/07

JAEA-Research-2020-006.pdf:4.84MB

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 last year of the three-year plan.

Formation of silicon oxynitride film using 5eV O atom and hyperthermal N beam exposures

Tagawa, Masahito*; Yokota, Kumiko*; Nishizaki, Noriaki*; Miyagai, Suguru*; Yoshigoe, Akitaka; Teraoka, Yuden

no journal, , 

Fast nitrogen molecular beams with 2 keV kinetic energy were irradiated at an Si(001) surface with an ultra-thin oxide overlayer. Photoemission peaks of bulk Si atoms became to be not clear. This fact indicates that nitrogen molecules transmitted from the oxide film react with bulk Si atoms. On the other hand, slow nitrogen molecular beams with 1.6 eV to 6.9 eV incident energy were irradiated at the oxide film. The surfaces were observed by photoemission spectroscopy with synchrotron radiation. With increasing the incident energy, SiN-related part in the Si2p photoemission peak increased in the bulk-sensitive measurements rather than surface-sensitive measurements. This fact reveals that nitrogen molecules are impinged into the oxide film even in such low energy and chemical bonds with Si atoms are formed near the interface.