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JAEA Reports

Annual report on the environmental radiation monitoring around the Tokai Reprocessing Plant FY2022

Kokubun, Yuji; Nakada, Akira; Seya, Natsumi; Koike, Yuko; Nemoto, Masashi; Tobita, Keiji; Yamada, Ryohei*; Uchiyama, Rei; Yamashita, Daichi; Nagai, Shinji; et al.

JAEA-Review 2023-046, 164 Pages, 2024/03

JAEA-Review-2023-046.pdf:4.2MB

The Nuclear Fuel Cycle Engineering Laboratories conducts environmental radiation monitoring around the reprocessing plant in accordance with the "Safety Regulations for Reprocessing Plant of JAEA, Part IV: Environmental Monitoring". This report summarizes the results of environmental radiation monitoring conducted during the period from April 2022 to March 2023 and the results of dose calculations for the surrounding public due to the release of radioactive materials into the atmosphere and ocean. In the results of the above environmental radiation monitoring, many items were affected by radioactive materials emitted from the accident at the Fukushima Daiichi Nuclear Power Plant of Tokyo Electric Power Company, Incorporated (changed to Tokyo Electric Power Company Holdings, Inc. on April 1, 2016), which occurred in March 2011. Also included as appendices are an overview of the environmental monitoring plan, an overview of measurement methods, measurement results and their changes over time, meteorological statistics results, radioactive waste release status, and an evaluation of the data which deviated of the normal range.

Journal Articles

Chemical composition of sediments from marine shallow-water hydrothermal mounds in Wakamiko submarine crater revealed by multiple prompt $$gamma$$-ray analysis

Shozugawa, Katsumi*; Matsuo, Motoyuki*; Sano, Yuji*; Toh, Yosuke; Murakami, Yukihiro*; Furutaka, Kazuyoshi; Koizumi, Mitsuo; Kimura, Atsushi; Hara, Kaoru; Kin, Tadahiro; et al.

Journal of Radioanalytical and Nuclear Chemistry, 291(2), p.341 - 346, 2012/02

https://doi.org/10.1007/s10967-011-1347-9
 Times Cited Count：3 Percentile：24.98(Chemistry, Analytical)

Multiple prompt $$gamma$$-ray analysis (MPGA), a new quantification method with high energy resolution, was applied to sediments from a marine shallow-water hydrothermal mound. Surface sediments around mounds were collected from the Wakamiko submarine crater located in Kagoshima Bay, southwest Japan, where the hydrothermal system was different from those at other marine shallow-water hydrothermal mounds. All samples were desalted and MPGA measurements were performed for 4,500 s (real time). Event data were obtained using eight CLOVER Ge detectors. We could obtain concentrations of $$^{32}$$S, $$^{55}$$Mn, $$^{75}$$As, $$^{157}$$Gd, $$^{39}$$K, $$^{149}$$Sm, $$^{56}$$Fe, and $$^{85}$$Rb with high sensitivity by MPGA. Furthermore, $$^{32}$$S, $$^{85}$$Rb, and $$^{55}$$Mn have characteristic concentrations only at a mound, suggesting that sediments were sulfated by magmatic fluids at this mound.

Journal Articles

Effects of oxygen annealing on dielectric properties of LuFeCuO$$_{4}$$

Matsuo, Yoji*; Suzuki, Muneyasu*; Noguchi, Yuji*; Yoshimura, Takeshi*; Fujimura, Norifumi*; Yoshii, Kenji; Ikeda, Naoshi*; Mori, Shigeo*

Japanese Journal of Applied Physics, 47(11), p.8464 - 8467, 2008/11

https://doi.org/10.1143/JJAP.47.8464
 Times Cited Count：11 Percentile：42.15(Physics, Applied)

We have investigated the physical properties of LuFeCuO$$_{4}$$, which is a derivative material of the electronic ferroelectric LuFe$$_{2}$$O$$_{4}$$. From electron diffraction measurements at room temperature, ionic ordering of Fe$$^{3+}$$ and Cu$$^{2+}$$ in the a-b plane was observed. This ordering is similar to that in LuFe$$_{2}$$O$$_{4}$$ and has an electric dipole. The observation of small domains (5-10 nm) indicates the presence of polar regions. Dielectric measurements showed that a peak of dielectric constant appeared at around 500 K, and the peak value was about 1000, indicating that LuFeCuO$$_{4}$$ is a dielectric material. We will present the experimental data on the samples prepared under high-pressure oxygen.

JAEA Reports

Reliability improvement of hydro-geochemical and hydrogeological model on geological environment in Horonobe Underground Research Laboratory project; Report on the 2005 FY research (Joint research)

Hama, Katsuhiro; Kunimaru, Takanori; Kurikami, Hiroshi; Sasamoto, Hiroshi; Takahashi, Yasuhiro*; Haginuma, Masashi*; Ishii, Tomoko*; Matsuo, Yuji*

JAEA-Research 2006-070, 93 Pages, 2006/09

JAEA-Research-2006-070.pdf:23.48MB
JAEA-Research-2006-070(errata).pdf:0.08MB

Japan Atomic Energy Agency and Institute of Research and Innovation have started collaborative study in order to enhance the reliability of technology for the geological disposal of High-level Radioactive Waste (HLW) since 2005 fiscal year. In this collaborative study, the analysis has carried out to estimate long-term evolution of groundwater chemistry and groundwater flow. The study items and results are summarized in this report. (1) Groundwater Chemistry. The following items have been carried out: 1. Multivariate analysis. 2. Estimation of distribution of groundwater chemistry. 3. Construction of geochemical model. (2) Groundwater Flow: 1. Construction of geological model. 2. Construction of hydrogeological model. 3. Groundwater flow analysis. The modeling work will be continued in 2006 fiscal year. The applicability of the modeling methodology will also be evaluated.

Oral presentation

Applied-electric-field dependence of charge ordered phase in the trianglular-lattice system LuFe$$_{2}$$O$$_{4}$$

Hayakawa, Hironori*; Kubota, Masato*; Oishi, Daisuke*; Akahama, Yuji*; Matsuo, Yoji*; Ikeda, Naoshi*; Kambe, Takashi*; Kimizuka, Noboru*; Yoshii, Kenji

no journal, , 

We have investigated the change of charge-ordered state in LuFe$$_{2}$$O$$_{4}$$ caused by an applied electric field. The application of the field above a threshold led to a drastic decrease in resistivity; this behavior corresponds to the change of charge-ordered structure observed using synchrotron radiation. More details will be shown at the conference.

Oral presentation

Multiferroic behavior and magnetic phase diagram of LuFe$$_{2}$$O$$_{4}$$

Oishi, Daisuke*; Hayakawa, Hironori*; Akahama, Yuji*; Funae, Takeshi*; Matsuo, Yoji*; Ikeda, Naoshi*; Kambe, Takashi*; Kimizuka, Noboru*; Yoshii, Kenji

no journal, , 

We have investigated the multiferroic behavior and the magnetic phase diagram of single-crystalline electronic ferroelectric LuFe$$_{2}$$O$$_{4}$$. Dielectric measurements under an applied magnetic field showed large magneto-capacitance at around room temperature. A complex magnetic phase diagram was obtained from detailed magnetic measurements below about room temperature. More details will be shown at the conference.

Oral presentation

Charge-order structure and physical properties of YbFe$$_{2-x}$$Mn$$_{x}$$O$$_{4}$$

Matsumoto, Keisuke*; Matsuo, Yoji*; Oishi, Daisuke*; Akahama, Yuji*; Yoshii, Kenji; Hanasaki, Noriaki*; Kambe, Takashi*; Ikeda, Naoshi*; Kimizuka, Noboru*; Mori, Shigeo*

no journal, , 

We have investigated the charge-ordered structure and physical properties of YbFe$$_{2-x}$$Mn$$_{x}$$O$$_{4}$$. Electron diffraction measurements showed a disappearance of charge-ordered structure of Fe ions by the Mn substitution. The Mn substitution also led to a monotonic decrease in magnetic transition temperature, low-temperature magnetization and dielectric constants. The results are explained in connection with several factors such as short-range ionic order.

Oral presentation

Tritium removal test for decommissioning of FUGEN

Matsushima, Akira; Ishiyama, Masahiro; Matsuo, Hidehiko; Sato, Yuji

no journal, , 

no abstracts in English

Oral presentation

Heat capacity measurements of cement materials

Sasada, Yuto*; Miyazaki, Yuji*; Nakano, Motohiro*; Matsuo, Yusuke*; Walker, C.*; Sasamoto, Hiroshi; Mihara, Morihiro

no journal, , 

Cementitous materials are to be used in large quantities in the geological disposal of highly radioactive TRU waste. Thermodynamic data on cement hydrate minerals are important to model the long-term dissolution behavior of cement materials during the reaction of these materials with groundwater. Portlandite (Ca(OH)$$_{2}$$) is a major component (20 to 25 wt%) of hydrated Portland cement. Low temperature heat capacity measurements of three types of portlandite (low purity, high purity, and large crystal) showed purity dependence. The large crystal sample followed Debye's T$$^{3}$$ rule at low temperatures, while the high and low purity samples showed upturn of heat capacity, possibly due to difference in absorbed water vapor and/or calcite (CaCO$$_{3}$$) contamination. Heat capacities of the cement hydrates (ettringite:Ca$$_{6}$$(Al(OH)$$_{6}$$)$$_{2}$$(SO$$_{4}$$)$$_{3}$$(H$$_{2}$$O)$$_{n}$$ and monosulfate:Ca$$_{4}$$Al$$_{2}$$(OH)$$_{12}$$(SO$$_{4}$$)(H$$_{2}$$O)$$_{n}$$) exhibited phase transitions associated with the hydration water.

Oral presentation

Preparation and characterization of bismuth-based ferri-dielectric ceramics

Noguchi, Suzunosuke*; Yoneda, Yasuhiro; Matsuo, Hiroki*; Noguchi, Yuji*

no journal, , 

The solid solution Bi$$_{(1-x)/2}$$Na$$_{(1-x)/2}$$Ba$$_x$$TiO$$_3$$ (BNT-BT) of the lead-free perovskite ferroelectrics Bi$$_{0.5}$$Na$$_{0.5}$$TiO$$_3$$ (BNT, space group: R3c) and BaTiO$$_3$$ (BT, space group: P4mm) is morphotropic phase boundary (MPB) and has attracted much attention because of its excellent piezoelectricity at MPB. In this study, we aim to control the electric field-induced phase transition and to complete the two-dimensional phase diagram of BNT-BT ceramics before and after the application of an electric field. The dielectric P4bm phase was found to be stabilized at a composition near MPB and with large A-site vacancies in BNT-BT solid solution ceramics.

Oral presentation

Creation of novel ferri-dielectrics and control of their electric-field-induced phase transitions

Fukushima, Kento*; Yoneda, Yasuhiro; Matsuo, Hiroki*; Noguchi, Yuji*

no journal, , 

A lead-free perovskite ferroelectric, (Bi,Na)TiO$$_3$$ (rhombohedral R3c), has attracted much attention because it forms a morphotropic phase boundary (MPB) with a tetragonal P4mm ferroelectric [BaTiO$$_3$$, (Bi,K)TiO$$_3$$] and shows excellent piezoelectricity in the MPB. P4bm phase, which exhibits ferri-dielectricity in the vicinity of the MPB, has been found to exist. In this study, we aim to clarify the compositional phase diagram of (Bi,Na)TiO$$_3$$-based solid solution ceramics with strict composition control and to elucidate the whole picture of their polarization properties. bm and the phase boundary between P4bm and P4mm were identified.

Oral presentation

Ferri-electricity in (Bi$$_{1/2}$$K$$_{1/2}$$)TiO$$_3$$-(Bi$$_{1/2}$$Li$$_{1/2}$$)TiO$$_3$$ solid solution

Saito, Kotaro*; Yoneda, Yasuhiro; Matsuo, Hiroki*; Noguchi, Yuji*

no journal, , 

In addition to excellent piezoelectricity and dielectric properties, ferri-dielectric phases exhibit giant electric-field-induced strain due to the electric-field-induced phase transition. The presence of ferri-dielectric phase and its properties were investigated for (Bi$$_{1/2}$$K$$_{1/2}$$)TiO$$_3$$-(Bi$$_{1/2}$$Li$$_{1/2}$$)TiO$$_3$$ (BKT-BLT) solid solution ceramics by searching for compositional phase boundaries and evaluating the composition dependence of polarization properties through crystal structure analysis. This study revealed that a ferri-dielectric phase exists around $$x$$ = 8% in the BKT-BLT solid solution system, and that a specifically high relative permittivity can be obtained at this composition.

Oral presentation

Effect of chemical pressure on phase stability of antiferroelectric NaNbO$$_3$$

Aso, Seiyu*; Yoneda, Yasuhiro; Matsuo, Hiroki*; Noguchi, Yuji*

no journal, , 

We have attempted to introduce positive chemical pressure into NaNbO$$_3$$ by replacing Na$$^+$$ with a small Ca$$^{2+}$$. The superlattice reflections originating from the antiferroelectric P phase appeared both before and after the application of an electric field, which confirmed that a reversible electric-field-induced phase transition was achieved.

Oral presentation

Ferroelectric properties of donor-acceptor co-doped BaTiO$$_3$$ ceramics

Kuwata, Kenta*; Matsuo, Hiroki*; Noguchi, Yuji*; Yoneda, Yasuhiro

no journal, , 

Barium titanate (BaTiO$$_3$$) is doped with transition metal (TM) ions such as Ni, which act as acceptors to trap electronic carriers (electrons or holes) generated by reductive calcination. In this study, we fabricated BaTiO$$_3$$ ceramics co-doped with Dy and La and evaluated their ferroelectric and photovoltaic properties. It was found that the Ni valence can be controlled by Dy/Ni co-doping and that the visible photovoltaic effect can be enhanced by introducing impurity levels derived from Ni-3d.

Oral presentation

Crystal structure analysis of NaNbO$$_3$$ in high-temperature phase

Aso, Seiyu*; Matsuo, Hiroki*; Noguchi, Yuji*; Yoneda, Yasuhiro; Morikawa, Daisuke*; Tsuda, Kenji*

no journal, , 

Recently, higher energy storage density than that of typical ferroelectric BaTiO$$_3$$ has been achieved in NaNbO$$_3$$-based antiferroelectrics by utilizing the electric-field-induced phase transition between the antiferroelectric (AFE) and ferroelectric (FE) phases. In this study, we attempted to identify the space group using synchrotron X-ray diffraction and convergent electron diffraction in order to elucidate the full picture of the phase transition behavior in NaNbO$$_3$$ and Ca-doped NaNbO$$_3$$. On the other hand, the Ca-doped sample showed that the space group is Pnma, which is consistent with the results obtained by convergent electron diffraction measurements.

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