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JAEA Reports

Annual report on the environmental radiation monitoring around the Tokai Reprocessing Plant FY 2018

Nakano, Masanao; Fujii, Tomoko; Nemoto, Masashi; Tobita, Keiji; Kono, Takahiko; Hosomi, Kenji; Nishimura, Shusaku; Matsubara, Natsumi; Maehara, Yushi; Narita, Ryosuke; et al.

JAEA-Review 2019-048, 165 Pages, 2020/03

JAEA-Review-2019-048.pdf:2.69MB

Environmental radiation monitoring around the Tokai Reprocessing Plant has been performed by the Nuclear Fuel Cycle Engineering Laboratories, based on "Safety Regulations for the Reprocessing Plant of Japan Atomic Energy Agency, Chapter IV - Environmental Monitoring". This annual report presents the results of the environmental monitoring and the dose estimation to the hypothetical inhabitant due to the radioactivity discharged from the plant to the atmosphere and the sea during April 2018 to March 2019. In this report, some data include the influence of the accidental release from the Fukushima Daiichi Nuclear Power Station of Tokyo Electric Power Co., Inc. (the trade name was changed to Tokyo Electric Power Company Holdings, Inc. on April 1, 2016) in March 2011. Appendices present comprehensive information, such as monitoring programs, monitoring methods, monitoring results and their trends, meteorological data and discharged radioactive wastes. In addition, the data which were influenced by the accidental release and exceeded the normal range of fluctuation in the monitoring, were evaluated.

Journal Articles

Ion beam induced luminescence of complexes formed in adsorbent for MA recovery process

Watanabe, So; Katai, Yuya*; Matsuura, Haruaki*; Kada, Wataru*; Koka, Masashi*; Sato, Takahiro*; Arai, Tsuyoshi*

Nuclear Instruments and Methods in Physics Research B, 450, p.61 - 65, 2019/07

 Times Cited Count:0 Percentile:100(Instruments & Instrumentation)

JAEA Reports

Annual report on the environmental radiation monitoring around the Tokai Reprocessing Plant FY 2017

Nakano, Masanao; Fujita, Hiroki; Mizutani, Tomoko; Nemoto, Masashi; Tobita, Keiji; Kono, Takahiko; Hosomi, Kenji; Hokama, Tomonori; Nishimura, Tomohiro; Matsubara, Natsumi; et al.

JAEA-Review 2018-025, 171 Pages, 2019/02

JAEA-Review-2018-025.pdf:3.81MB

Environmental radiation monitoring around the Tokai Reprocessing Plant has been performed by the Nuclear Fuel Cycle Engineering Laboratories, based on "Safety Regulations for the Reprocessing Plant of Japan Atomic Energy Agency, Chapter IV - Environmental Monitoring". This annual report presents the results of the environmental monitoring and the dose estimation to the hypothetical inhabitant due to the radioactivity discharged from the plant to the atmosphere and the sea during April 2016 to March 2017. In this report, some data include the influence of the accidental release from the Fukushima Daiichi Nuclear Power Station of Electric Power Company Holdings, Inc. in March 2011. Appendices present comprehensive information, such as monitoring programs, monitoring methods, monitoring results and their trends, meteorological data and discharged radioactive wastes. In addition, the data which were influenced by the accidental release and were exceeded the normal range of fluctuation in the monitoring, were evaluated.

Journal Articles

Benchmark study of DFT with Eu and Np M$"o$ssbauer isomer shifts using second-order Douglas-Kroll-Hess Hamiltonian

Kaneko, Masashi; Watanabe, Masayuki; Miyashita, Sunao*; Nakashima, Satoru*

Hyperfine Interactions, 239(1), p.20_1 - 20_10, 2018/12

 Times Cited Count:0 Percentile:100

We optimized a mixing ratio of exchange energy between pure DFT and exact Hartree-Fock using TPSS exchange-correlation functional to estimate the accurate coordination bonds in f-block complexes by numerically benchmarking with the experimental data of M$"o$ssbauer isomer shifts for $$^{151}$$Eu and $$^{237}$$Np nuclides. Second-order Douglas-Kroll-Hess Hamiltonian with segmented all-electron relativistically contracted basis set was employed to calculate the electron densities at Eu and Np nuclei, i.e. contact densities, for each five complexes for Eu(III) and Np(IV) systems. We compared the root mean square deviation values of their isomer shifts between experiment and calculation by changing the mixing ratio of Hartree-Fock exchange parameter from 0 to 100 % at intervals of 10 %. As the result, it was indicated that the mixing ratio of 30 and 60 % for Eu and Np benchmark systems, respectively, gives the smallest deviation values. Mulliken's spin population analysis indicated that the covalency in the metal-ligand bonds for both Eu and Np complexes decreases with increasing the Hartree-Fock exchange admixture.

Journal Articles

Computational chemical analysis of Eu(III) and Am(III) complexes with pnictogen-donor ligands using DFT calculations

Kimura, Taiki*; Kaneko, Masashi; Watanabe, Masayuki; Miyashita, Sunao*; Nakashima, Satoru*

Dalton Transactions (Internet), 47(42), p.14924 - 14931, 2018/11

 Times Cited Count:1 Percentile:81.9(Chemistry, Inorganic & Nuclear)

We demonstrated density functional calculations of Eu(III) and Am(III) complexes with pnictogen-donor (X) ligands, CH$$_{3}$$)$$_{2}$$X-CH$$_{2}$$-CH$$_{2}$$-X(CH$$_{3}$$)$$_{2}$$ (X = N, P, As and Sb). We investigated the optimized structures of the cmoplexes and the Gibbs energy differences in the complex formation reactions. Those results indicated that the N- and P-donor ligands have Am(III) ion selectivity over Eu(III) ion, especially, the P-donor ligand showed the highest selectivity. The tendency of the Am(III)/Eu(III) selectivity by the pnictogen-dono ligands was found to be comparable to that of soft acid classification in hard and soft acids and bases rule. Mulliken's spin population analysis indicated that the bonding property between the metal ion and the pnictogen atoms correlated with the Am(III)/Eu(III) selectivity. In particular, the participation of f-orbital electrons of the metal ion in the covalency was indicated to have an important role for the selectivity.

Journal Articles

Variation of half-life and internal-conversion electron energy spectrum between $$^{235m}$$U oxide and fluoride

Shigekawa, Yudai*; Kasamatsu, Yoshitaka*; Yasuda, Yuki*; Kaneko, Masashi; Watanabe, Masayuki; Shinohara, Atsushi*

Physical Review C, 98(1), p.014306_1 - 014306_5, 2018/07

 Times Cited Count:1 Percentile:73.02(Physics, Nuclear)

The nuclear half-life of $$^{235m}$$U has been reported to vary depending on the chemical environment. In this study, both the half-life and the internal-conversion (IC) electron energy spectrum were measured for $$^{235m}$$U with identical chemical environments for the first time. $$^{235m}$$U oxide and fluoride samples were subjected to these measurements, and clear differences in the half-life and the energy spectrum between these samples were observed. The peaks in the energy spectra were identified with the relativistic density functional theory calculation, and the molecular orbital states of the $$^{235m}$$U oxide and fluoride estimated from the energy spectra and the calculation qualitatively explained the difference in the half-lives between the samples.

Journal Articles

Correlation between Am(III)/Eu(III) selectivity and covalency in metal-chalcogen bonds using density functional calculations

Kaneko, Masashi; Watanabe, Masayuki

Journal of Radioanalytical and Nuclear Chemistry, 316(3), p.1129 - 1137, 2018/06

 Times Cited Count:5 Percentile:13.57(Chemistry, Analytical)

We applied density functional theory calculations to Am(III) and Eu(III) complexes with chalcogen-donor ligands of the formula N(EPMe$$_{2}$$)$$_{2}$$$$^{-}$$ (E = O, S, Se, Te). We calculated the equilibrium structures and relative stabilities of the complexes in the complexation reaction. The results indicated that the tendency of the relative stability is O $$ll$$ S $$sim$$ Se $$sim$$ Te, which is consistent with the trend of soft acid classification. Molecular orbital overlap population analysis suggested that this tendency can be correlated with the bonding type in the covalent interaction between the f-orbitals of the metal atom and the chalcogen-donor atoms.

Journal Articles

Modeling and simulation of redistribution of oxygen-to-metal ratio in MOX

Hirooka, Shun; Kato, Masato; Watanabe, Masashi

Transactions of the American Nuclear Society, 118, p.1624 - 1626, 2018/06

This study suggested the time development of oxygen-to-metal ratio (O/M) redistribution model with oxygen-related properties in MOX. Irradiation simulation including the suggested O/M redistribution and pore migration with vaporization-condensation model which bares density redistribution was demonstrated. The simulation results showed that O/M redistribution proceeded at lower temperature than density redistribution, which indicated that oxygen diffusion got influential at lower temperature than vaporization-condensation of MOX. Another find was that O/M redistribution was very slow at the surface because temperature kept low. However, near the surface (inside from the surface) where the temperature exceeded 1000 K, O/M redistribution was rather recognizable with oxygen flown from inner region to the near-surface. The results will be evaluated by comparison with post-irradiation examination data.

JAEA Reports

Annual report on the environmental radiation monitoring around the Tokai Reprocessing Plant FY 2016

Nakano, Masanao; Fujita, Hiroki; Mizutani, Tomoko; Nemoto, Masashi; Tobita, Keiji; Hosomi, Kenji; Nagaoka, Mika; Hokama, Tomonori; Nishimura, Tomohiro; Koike, Yuko; et al.

JAEA-Review 2017-028, 177 Pages, 2018/01

JAEA-Review-2017-028.pdf:3.61MB

Environmental radiation monitoring around the Tokai Reprocessing Plant has been performed by the Nuclear Fuel Cycle Engineering Laboratories, based on "Safety Regulations for the Reprocessing Plant of Japan Atomic Energy Agency, Chapter IV - Environmental Monitoring". This annual report presents the results of the environmental monitoring and the dose estimation to the hypothetical inhabitant due to the radioactivity discharged from the plant to the atmosphere and the sea during April 2016 to March 2017. In this report, some data include the influence of the accidental release from the Fukushima Daiichi Nuclear Power Station of Electric Power Company Holdings, Inc. in March 2011. Appendices present comprehensive information, such as monitoring programs, monitoring methods, monitoring results and their trends, meteorological data and discharged radioactive wastes. In addition, the data which were influenced by the accidental release and were exceeded the normal range of fluctuation in the monitoring, were evaluated.

Journal Articles

Dose-reduction effects of vehicles against gamma radiation in the case of a nuclear accident

Takahara, Shogo; Watanabe, Masatoshi*; Hirouchi, Jun; Iijima, Masashi*; Munakata, Masahiro

Health Physics, 114(1), p.64 - 72, 2018/01

AA2017-0033.pdf:0.55MB

 Times Cited Count:1 Percentile:67.8(Environmental Sciences)

Journal Articles

Determination of fusion barrier distributions from quasielastic scattering cross sections towards superheavy nuclei synthesis

Tanaka, Taiki*; Narikiyo, Yoshihiro*; Morita, Kosuke*; Fujita, Kunihiro*; Kaji, Daiya*; Morimoto, Koji*; Yamaki, Sayaka*; Wakabayashi, Yasuo*; Tanaka, Kengo*; Takeyama, Mirei*; et al.

Journal of the Physical Society of Japan, 87(1), p.014201_1 - 014201_9, 2018/01

 Times Cited Count:5 Percentile:27.92(Physics, Multidisciplinary)

Excitation functions of quasielastic scattering cross sections for the $$^{48}$$Ca + $$^{208}$$Pb, $$^{50}$$Ti + $$^{208}$$Pb, and $$^{48}$$Ca + $$^{248}$$Cm reactions were successfully measured by using the gas-filled recoil-ion separator GARIS. Fusion barrier distributions were extracted from these data, and compared with the coupled-channels calculations. It was found that the peak energies of the barrier distributions for the $$^{48}$$Ca + $$^{208}$$Pb and $$^{50}$$Ti + $$^{208}$$Pb systems coincide with those of the 2n evaporation channel cross sections for the systems, while that of the $$^{48}$$Ca + $$^{248}$$Cm is located slightly below the 4n evaporation ones. This results provide us helpful information to predict the optimum beam energy to synthesize superheavy nuclei.

Journal Articles

Identification of penetration path and deposition distribution of radionuclides in houses by experiments and numerical model

Hirouchi, Jun; Takahara, Shogo; Iijima, Masashi; Watanabe, Masatoshi; Munakata, Masahiro

Radiation Physics and Chemistry, 140, p.127 - 131, 2017/11

 Times Cited Count:0 Percentile:100(Chemistry, Physical)

Journal Articles

Local structure and distribution of remaining elements inside extraction chromatography adsorbents

Watanabe, So; Sano, Yuichi; Shiwaku, Hideaki; Yaita, Tsuyoshi; Ono, Shimpei*; Arai, Tsuyoshi*; Matsuura, Haruaki*; Koka, Masashi*; Sato, Takahiro*

Nuclear Instruments and Methods in Physics Research B, 404, p.202 - 206, 2017/08

 Times Cited Count:2 Percentile:58.53(Instruments & Instrumentation)

Journal Articles

Microscopic analyses of complexes formed in adsorbent for Mo and Zr separation chromatography

Abe, Ryoji*; Nagoshi, Kohei*; Arai, Tsuyoshi*; Watanabe, So; Sano, Yuichi; Matsuura, Haruaki*; Takagi, Hideaki*; Shimizu, Nobutaka*; Koka, Masashi*; Sato, Takahiro*

Nuclear Instruments and Methods in Physics Research B, 404, p.173 - 178, 2017/08

 Times Cited Count:0 Percentile:100(Instruments & Instrumentation)

Journal Articles

Bonding study on trivalent europium complexes by combining M$"o$ssbauer isomer shifts with density functional calculations

Kaneko, Masashi; Watanabe, Masayuki; Miyashita, Sunao*; Nakashima, Satoru*

Radioisotopes, 66(8), p.289 - 300, 2017/08

Scalar-relativistic density functional calculations applied to some trivalent europium complexes. Five Eu(III) complexes whose $$^{151}$$Eu M$"o$ssbauer isomer shifts vary from -1.8 to 0.5 mm/s are referred by previously reported results. Geometrical optimizations of their complexes reproduces the experimental coordination structures. Single-point calculations are applied to their optimized geometries at three density functionals, namely, BP86, B3LYP, and B2PLYP, to obtain their electron densities at Eu nucleus. A comparison of the linearity between the electron densities and the corresponding $$^{151}$$Eu M$"o$ssbauer isomer shifts reveals that B2PLYP functional shows the best linearity. Electron population and bond analyses indicate that d- and f-orbital electrons of Eu ion in the complexes are found to be correlated to the experimental $$^{151}$$Eu M$"o$ssbauer isomer shifts. This indicates that the d- and f-orbital electrons are involved in the covalent interaction of the coordination bond between the Eu ion and the ligands.

Journal Articles

Oxygen chemical diffusion coefficients of (U, Pu)O$$_{2-x}$$

Watanabe, Masashi; Sunaoshi, Takeo*; Kato, Masato

Defect and Diffusion Forum, 375, p.84 - 90, 2017/05

The oxygen chemical diffusion coefficient in (U, Pu)O$$_{2-x}$$ was determined by thermo-gravimetry as functions of the Pu content, oxygen-to-metal ratio and temperature. The surface reaction was considered in the diffusion coefficient determination. The activation energy for the chemical diffusion coefficient was 60 kJ/mol and 65 kJ/mol, respectively, in (U$$_{0.8}$$Pu$$_{0.2}$$)O$$_{2-x}$$ and (U$$_{0.7}$$Pu$$_{0.3}$$)O$$_{2-x}$$.

Journal Articles

Defect chemistry and basic properties of non-stoichiometric PuO$$_{2}$$

Kato, Masato; Nakamura, Hiroki; Watanabe, Masashi; Matsumoto, Taku; Machida, Masahiko

Defect and Diffusion Forum, 375, p.57 - 70, 2017/05

The basic properties of PuO$$_{2-x}$$ were reviewed, and the equilibrium defects in PuO$$_{2-x}$$ were evaluated from the experimental data of the oxygen potential and electrical conductivity as well as the Ab-initio calculation results. Consistency among various properties was confirmed, and the mechanistic models for thermal property representations were derived.

Journal Articles

Oxygen potentials, oxygen diffusion coefficients and defect equilibria of nonstoichiometric (U,Pu)O$$_{2pm x}$$

Kato, Masato; Watanabe, Masashi; Matsumoto, Taku; Hirooka, Shun; Akashi, Masatoshi

Journal of Nuclear Materials, 487, p.424 - 432, 2017/04

 Times Cited Count:1 Percentile:76.68(Materials Science, Multidisciplinary)

Oxygen potential of (U,Pu)O$$_{2pm x}$$ was evaluated based on defect chemistry using an updated experimental data set. The relationship between oxygen partial pressure and deviation $$x$$ in (U,Pu)O$$_{2pm x}$$ was analyzed, and equilibrium constants of defect formation were determined as functions of Pu content and temperature. Brouwer's diagrams were constructed using the determined equilibrium constants, and a relational equation to determine O/M ratio was derived as functions of O/M ratio, Pu content and temperature. In addition, relationship between oxygen potential and oxygen diffusion coefficients were described.

JAEA Reports

Annual report on the environmental radiation monitoring around the Tokai Reprocessing Plant FY 2015

Nakano, Masanao; Fujita, Hiroki; Mizutani, Tomoko; Hosomi, Kenji; Nagaoka, Mika; Hokama, Tomonori; Yokoyama, Hiroya; Nishimura, Tomohiro; Matsubara, Natsumi; Maehara, Yushi; et al.

JAEA-Review 2016-035, 179 Pages, 2017/03

JAEA-Review-2016-035.pdf:4.2MB

Environmental radiation monitoring around the Tokai Reprocessing Plant has been performed by the Nuclear Fuel Cycle Engineering Laboratories, based on "Safety Regulations for the Reprocessing Plant of Japan Atomic Energy Agency, Chapter IV - Environmental Monitoring". This annual report presents the results of the environmental monitoring and the dose estimation to the hypothetical inhabitant due to the radioactivity discharged from the plant to the atmosphere and the sea during April 2015 to March 2016. In this report, some data include the influence of the accidental release from the Fukushima Daiichi Nuclear Power Station of Electric Power Company Holdings, Inc. in March 2011. Appendices present comprehensive information, such as monitoring programs, monitoring methods, monitoring results and their trends, meteorological data and discharged radioactive wastes. In addition, the data which were influenced by the accidental release and were exceeded the normal range of fluctuation in the monitoring, were evaluated.

Journal Articles

Roles of d- and f-orbital electrons in the complexation of Eu(III) and Am(III) ions with alkyldithiophosphinic acid and alkylphosphinic acid using scalar-relativistic DFT calculations

Kaneko, Masashi; Watanabe, Masayuki; Miyashita, Sunao*; Nakashima, Satoru*

Journal of Nuclear and Radiochemical Sciences (Internet), 17, p.9 - 15, 2017/03

Density functional calculations were applied to the complexation of Eu(III) and Am(III) ions with phosphinic acid (O-donor) and dihiophosphinic acid (S-donor) from the viewpoint of the bonding nature of valence orbitals in metal ion. Two and four conformers for S-donor and O-donor complexes, respectively were optimized. Their stabilization energies by complex formation toward [M(H$$_{2}$$O)$$_{9}$$]$$^{3+}$$ were estimated. As the result, the energies reproduced the experimental Am(III)/Eu(III) selectivity that O-donor ligand preferably coordinates to Eu(III) ion, whereas S-donor ligand selectively coordinates to Am(III) ion. Focused on the bonding natures of d and f-orbital electrons, it was indicated that the d-orbital electrons in both Eu and Am complexes participate in the covalency as bonding-type nature and have the almost same contribution. Meanwhile, the contribution of the f-orbital electrons was different between Eu and Am complexes and indicated that in the case of S-donor complex, non-bonding type and bonding type contributions were observed for Eu and Am complexes, respectively and in the case of O-donor complex, bonding type and anti-bonding type contributions were observed for Eu and Am complexes, respectively. This result suggested that the bonding natures of d-orbital electrons contribute to the geometrical similarity of molecular structures for Eu and Am complexes and the bonding natures of f-orbital electrons contribute to the difference in the selectivity of Eu and Am ions.

141 (Records 1-20 displayed on this page)