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Oka, Hiroshi*; Tanno, Takashi; Yano, Yasuhide; Otsuka, Satoshi; Kaito, Takeji; Hashimoto, Naoyuki*
Journal of Nuclear Materials, 572, p.154032_1 - 154032_8, 2022/12
Times Cited Count：3 Percentile：68.71(Materials Science, Multidisciplinary)9Cr oxide dispersion strengthened steels with slightly different nitrogen concentrations (0.0034 - 0.029 wt%) were prepared and their creep property at 973 K was investigated with microstructural characterization before and after the creep test. The creep strength decreased significantly as the nitrogen concentration increased. Microstructural observation revealed that, in the higher nitrogen concentration specimen, coarse Y-rich inclusions were found along the boundary between transformed ferrite region and residual ferrite region. The solubility difference of nitrogen in 
and 
phase would induce the localized increment of nitrogen concentration in the boundary region during the austenitizing process, resulting in the thermodynamic destabilization and subsequent coarsening of the dispersed oxide particles. The rows of creep voids were found near the rupture part of the crept specimen, suggesting that the coarse inclusions were the starting point of creep void formation and the subsequent premature fracture.
ambient on threshold voltage stability in 4H-SiC metal-oxide-semiconductor field-effect transistorsHosoi, Takuji*; Osako, Momoe*; Moges, K.*; Ito, Koji*; Kimoto, Tsunenobu*; Sometani, Mitsuru*; Okamoto, Mitsuo*; Yoshigoe, Akitaka; Shimura, Takayoshi*; Watanabe, Heiji*
Applied Physics Express, 15(6), p.061003_1 - 061003_5, 2022/06
Times Cited Count：2 Percentile：34.67(Physics, Applied)The combination of NO annealing and subsequent post-nitridation annealing (PNA) in CO ambient for SiO/SiC structures has been demonstrated to be effective in obtaining both high channel mobility and superior threshold voltage stability in SiC-based metal-oxide-semiconductor field-effect transistors (MOSFETs). N atoms on the SiO side of the SiO/SiC interface incorporated by NO annealing, which are plausible cause of charge trapping sites, could be selectively removed by CO-PNA at 1300
C without oxidizing the SiC. CO-PNA was also effective in compensating oxygen vacancies in SiO, resulting high immunity against both positive and negative bias-temperature stresses.
Iwasa, Toma; Takano, Masahide
JAEA-Technology 2020-024, 29 Pages, 2021/03
JAEA-Technology-2020-024.pdf:2.33MB
Partitioning and transmutation of minor actinides (MA) is an important issue to reduce volume and radio-toxicity of high-level radioactive wastes. In Nuclear Science Research Institute, we have been carrying out R&D on MA-bearing nitride fuel for accelerator driven system. In the actual nitride fuel fabrication process, a special nitrogen gas highly enriched with 
N is required to avoid 
C production from N by (n,p) reaction in the fuel. For the economical use of such expensive gas, we need a nitrogen circulation refining system that can remove carbon monoxide (CO) evolved by carbothermic nitridation of oxides and can use the nitrogen gas in the closed system without loss. To develop the system, at first we listed up the performance requirements, and then designed and assembled a prototype system for laboratory-scale demonstration. The system consists of CO removal unit and circulation unit that can automatically keep the system pressure and the gas flow rate constant. As a result of demonstration on the nitridation of oxide, both units completely satisfy the requirements. We confirmed that the concept can be applied to the actual fuel fabrication with further additional function such as automatic hydrogen feed for the control of decarburization.
N isotopic enrichment plant and its cost for nitride fuel fabrication (Contract research)Takano, Masahide
JAEA-Review 2020-080, 24 Pages, 2021/03
JAEA-Review-2020-080.pdf:1.71MB
Nitride is one of the potential fuel forms for minor actinide transmutation by the accelerator driven system. However, to avoid the C production from N by (n, p) reaction in the fuel, the special N gas highly enriched with N is needed for the fuel fabrication. To realize the availability of such gas has been an important issue. In this report, the degree of N enrichment and gas amount required for the fuel fabrication are shown first, and then among the existing isotopic enrichment methods, N cryogenic distillation is found to be a promising method from the viewpoint of constructing a huge scale plant because of its non-hazardous feature. Some commercial plants for 
O enrichment based on the similar method have already been operated in Japan. Its technology and components can be applied to the N enrichment plant. Assuming the supply of N gas from a cryogenic distillation plant, a series of enrichment simulation is performed to evaluate the plant size as functions of targeted degree of enrichment and annual production. By using the simulation results, the basic specifications for plant components and equipment are designed. As a result, a huge plant for annual production of 1000 kg N gas with 99% enrichment is found to be technically feasible. The N gas production cost is also evaluated to be approximately 1/30 of the current distribution price. This survey shows the availability of N gas required for the nitride fuel fabrication in both technical and economic aspects.
Abe, Toru*; Hirano, Fumio; Mihara, Morihiro; Honda, Akira
Genshiryoku Bakkuendo Kenkyu (CD-ROM), 27(1), p.3 - 11, 2020/06
Degradation of TRU waste in a geological disposal facility may cause the formation of a nitrate plume. A Nitrate Evolution model due to mineral reactions, microbial activity, and metal corrosiON (NEON) has therefore been developed to evaluate the safety case for geological disposal of TRU waste. Small scale laboratory experiments can be reproduced satisfactorily, however, it is necessary to demonstrate the applicability of the NEON model on scales relevant to the geological disposal of TRU waste. In the current study, an industrial analogue of a nitrate plume from the pollution of groundwater from nitrate fertilizers used on Ikuchi Island, Japan was selected to test the applicability of the NEON model. Concentration profiles of nitrate ions in the groundwater were successfully reproduced over the hundreds of meters scale demonstrating the applicability of the NEON model in evaluating the chemical behavior of a nitrate plume derived from the geological disposal of TRU waste.
C and 
N values of sediment-trap particles in the Japan and Yamato Basins and comparison with the core-top values in the East/Japan SeaKhim, B.-K.*; Otosaka, Shigeyoshi; Park, K.-A.*; Noriki, Shinichiro*
Ocean Science Journal, 53(1), p.17 - 29, 2018/03
Times Cited Count：5 Percentile：27.02(Marine & Freshwater Biology)Distribution of carbon and nitrogen stable isotope ratios (
C, N) in sinking particles collected in four stations in the Japan Sea was summarized. The C and N values in the sinking particles showed a clear seasonal variation, which agreed well with the variation in the chlorophyll a concentration in the surface seawater and in the sinking flux of biogenic particles. In particular, during the highly productive season of phytoplankton, a remarkable isotopic fractionation of N was found in the sinking particles, and it was inferred that the fractionation indicates the degree of nitrogen uptake by diatoms in the surface layer. These results are helpful information for linking the phenomenon in the ocean surface and the isotopic information recorded in the seafloor.
Ichikawa, Shoichi; Chiba, Yusuke; Ono, Fumiyasu; Hatori, Masakazu; Kobayashi, Takanori; Uekura, Ryoichi; Hashiri, Nobuo*; Inuzuka, Taisuke*; Kitano, Hiroshi*; Abe, Hisashi*
JAEA-Research 2016-021, 32 Pages, 2017/02
JAEA-Research-2016-021.pdf:5.0MB
In order to reduce the influence on a plant schedule of the MONJU by the maintenance of dew point hygrometers, The JAEA examined a capacitance type dew point hygrometer as an alternative dew point hygrometer for a lithium-chloride type dew point hygrometer which had been used at the CV-LRT in the MONJU. As a result of comparing a capacitance type dew point hygrometer with a lithium-chloride type dew point hygrometer at the CV-LRT (Atmosphere: nitrogen, Testing time: 24 hours), there weren't significant difference between a capacitance type dew point hygrometer and a lithium-chloride type dew point hygrometer. As a result of comparing a capacitance dew point hygrometer with a high-mirror-surface type dew point hygrometer for long term verification (Atmosphere: air, Testing time: 24 months), the JAEA confirmed that a capacitance type dew point hygrometer satisfied the instrument specification (
2.04C) required by the JEAC4203-2008.
Takeuchi, Tomoaki; Nakano, Hiroko; Uehara, Toshiaki; Tsuchiya, Kunihiko
Nuclear Materials and Energy (Internet), 9, p.451 - 454, 2016/12
Times Cited Count：1 Percentile：10.71(Nuclear Science & Technology)no abstracts in English
Wakai, Eiichi; Watanabe, Kazuyoshi*; Ito, Yuzuru*; Suzuki, Akihiro*; Terai, Takayuki*; Yagi, Juro*; Kondo, Hiroo; Kanemura, Takuji; Furukawa, Tomohiro; Hirakawa, Yasushi; et al.
Plasma and Fusion Research (Internet), 11, p.2405112_1 - 2405112_4, 2016/11
Yokota, Yuichiro; Funayama, Tomoo; Ikeda, Hiroko; Sakashita, Tetsuya; Suzuki, Michiyo; Kobayashi, Yasuhiko
JAEA-Review 2015-022, JAEA Takasaki Annual Report 2014, P. 67, 2016/02
The role of nitric oxide (NO) in bystander effect was investigated. Human fibroblasts were irradiated with -rays (LET: 0.2 keV/
m) or carbon-ion beam (108 keV/m), and then, co-cultured with the non-irradiated cells. After 24 h culture, the survival rates of non-irradiated cells and the concentrations of nitrate, an oxide of NO, in the medium were measured. The survival rates of non-irradiated cells decreased in dose-dependent and radiation quality-independent manners. Negative relationships between survival rates and nitrite concentrations existed, indicating the amounts of produced NO are an important determinant of bystander effects. Next, a reagent producing two molecules of NO in a half-life of 100 min was added in the culture medium. After incubation of 24 h the survival rates of treated cells did not decrease, suggesting NO produced intracellularly has an important role to lead the bystander effect but is not the signal molecule for intercellular communication.
Yokota, Yuichiro; Funayama, Tomoo; Ikeda, Hiroko; Kobayashi, Yasuhiko
Isotope News, (741), p.21 - 25, 2016/01
Our article published on the International Journal of Radiation Biology (2015) was reviewed. We investigated the dependence of the bystander cell-killing effect on radiation dose and quality, and related molecular mechanisms. Human fibroblasts were irradiated with -rays or carbon ions and co-cultured with non-irradiated cells. Survival rates of non-irradiated cells decreased and nitrite concentrations in co-culture medium increased with dose. Their dose responses were similar between -rays and carbon ions. Treatment of the specific nitric oxide (NO) radical scavenger prevented reductions in survival rates of non-irradiated cells. Negative relationships were observed between survival rates and nitrite concentrations. From these results, it was concluded that the bystander cell-killing effect mediated by NO radicals depends on irradiation doses, but not on radiation quality. NO radical production appears to be an important determinant of bystander effects.
Yokota, Yuichiro; Funayama, Tomoo; Muto, Yasuko*; Ikeda, Hiroko; Kobayashi, Yasuhiko
International Journal of Radiation Biology, 91(5), p.383 - 388, 2015/05
Times Cited Count：10 Percentile：64.63(Biology)We investigated the dependence of the bystander cell-killing effect on radiation dose and quality, and related molecular mechanisms. Human fibroblasts were irradiated with -rays or carbon ions and co-cultured with non-irradiated cells. Survival rates of non-irradiated cells decreased and nitrite concentrations in culture medium increased with increasing doses. Their dose responses were similar between -rays and carbon ions. Treatment of the specific nitric oxide (NO) radical scavenger prevented reductions in survival rates of non-irradiated cells. Negative relationships were observed between survival rates and nitrite concentrations. From these results, it was concluded that the bystander cell-killing effect mediated by NO radicals in human fibroblasts depends on irradiation doses, but not on radiation quality. NO radical production appears to be an important determinant of -ray- and carbon-ion-induced bystander effects.
Mannan, M. A.*; Baba, Yuji; Kida, Tetsuya*; Nagano, Masamitsu*; Noguchi, Hideyuki*
Materials Sciences and Applications, 6(5), p.353 - 359, 2015/05
The synthesis and structure of hexagonal boron carbonitride (h-BCN) film on polycrystalline diamond surface were reported. Polycrystalline diamond and/or diamond-like carbon were first fabricated on Si (100) and then it was used as substrate. The deposition was performed by radio frequency plasma enhanced chemical vapor deposition. In order to reduce the content of nitrogen void defects, the deposition was performed at the high temperature of 950C under the working pressure of 2.6 Pa. The typical sample with atomic composition of B
C
N
O
in the h-BCN lattice was characterized by X-ray photoelectron spectroscopy. The fine structure of the film was studied by near-edge X-ray absorption fine structure (NEXAFS) measurements. The B K-edge and N K-edge of NEXAFS spectra revealed that the synthesized h-BCN film has the ideal honeycomb-like BN
configuration without nitrogen void defects.
Yokota, Yuichiro; Funayama, Tomoo; Ikeda, Hiroko; Sakashita, Tetsuya; Suzuki, Michiyo; Kobayashi, Yasuhiko
JAEA-Review 2014-050, JAEA Takasaki Annual Report 2013, P. 75, 2015/03
We investigated the bystander effect induced by -rays or carbon ions and analyzed the role of nitric oxide (NO) in the effect. Normal human fibroblasts were used. Cells inoculated on a porous membrane were irradiated with varying doses of -rays or carbon ions. Irradiated cells were then non-contact co-cultured with non-irradiated cells for 24 h. After co-culture, the survival rates of non-irradiated bystander cells co-cultured with irradiated cells decreased with increasing dose and bottomed out at 0.5 Gy or higher doses. This indicates that the bystander effect is dependent on irradiation dose but independent of radiation quality. Next, a specific NO scavenger c-PTIO was added to the culture medium during irradiation and co-culture. This treatment prevented the reduction in survival rates of bystander cells, clearly indicating that NO has an important role in the bystander effect.
Saeki, Masakatsu; Nakada, Masami; Kawasaki, Takeshi*; Nishimura, Tatsuru*; Kitazawa, Takafumi*; Takeda, Masuo*
Journal of Radioanalytical and Nuclear Chemistry, 270(2), p.379 - 384, 2006/11
Times Cited Count：3 Percentile：24.11(Chemistry, Analytical)no abstracts in English
Kiriyama, Koji*; Shiwaku, Hideaki; Mochizuki, Tetsuro*; Shobu, Takahisa*; Tozawa, Kazukiyo*
JAERI-Tech 2005-003, 36 Pages, 2005/03
JAERI-Tech-2005-003.pdf:4.19MB
Multi-stabilizing methods for vibrations on the cryogenically cooled monochromator have been tried on BL11XU at SPring-8. Observed vibrations on crystals were mainly 1-10 Hz, 30 Hz, and 50 Hz. The results suggested that sources of the vibrations were liquid nitrogen flow and propagation from vibrations of vacuum pumps equipped with beam line. We took countermeasures of the vibrations to liquid nitrogen tubes, and set parameters (temperature, pressure and flow-late) of the cryogenic cooling system for 1-10 Hz vibration. Vibration absorber was set not to propagate the vibrations from the vacuum pumps and their fans for 30 and 50 Hz vibrations. These methods successfully removed the mechanical vibrations. Then, intensity vibration of X-ray was decreased from 4.47 % to 0.85 %, in the end. The stabilizing methods on BL11XU are expected to apply to the similar system at the other beam-lines.
" observation of guanine radicals induced by ultrasoft X-ray irradiation around the K-edge regions of nitrogen and oxygenYokoya, Akinari; Akamatsu, Ken; Fujii, Kentaro; Ukai, Masatoshi*
International Journal of Radiation Biology, 80(11-12), p.833 - 839, 2004/12
Times Cited Count：8 Percentile：48.81(Biology)no abstracts in English
ssbauer Isomer shifts and Structures of Neptunium compoundsSaeki, Masakatsu; Nakada, Masami; Kitazawa, Takafumi*
KURRI-KR-106, p.38 - 42, 2004/03
no abstracts in English
Tozawa, Kazukiyo*; Kiriyama, Koji*; Mitsui, Takaya; Shiwaku, Hideaki; Harami, Taikan
AIP Conference Proceedings 705, p.671 - 674, 2004/00
Liquid-N-cooled Si crystals replaced water-cooled diamond crystals for the double-crystal monochromator on BL11XU at SPring-8. To use the whole energy from 6keV to 70keV, we adopted the system of alternative dual symmetric Si geometry, Si(111)/Si(311), which can be switched by a horizontal translation (X) stage perpendicular to the beam axis. Before the experiment on BL11XU, the off-line evaluation was performed to estimate the degree of the crystal strain, which may arise from the way of assembling. With MoK
, rocking curves from the crystals were measured for the second crystal of the double-crystal diffractometer of parallel setting. Each of the observed FWHM was almost constant and identical to the calculated value wherever X-rays hit on the crystal surface. By the use of synchrotron radiation from the undulator the crystals were tested and then the characterization was performed. The observed intensities and rocking curves resulted in that each crystal was good for BL11XU and that the performance of X-ray reflection was improved.
Matsuhashi, Shimpei
Gamma Field Symposia, (43), p.71 - 79, 2004/00
We visualized the uptake and transportation of nutrition in a living plant using positron-emitting tracers and mathematical analysis of the data. We have been developing a positron-imaging technique to visualize the uptake and transportation of nutrients in a plant by a positron-emitting tracer-imaging system (PETIS) using positron-emitting nuclide-labeled compounds. The PETIS data is analyzed mathematically to understand the physiological meaning of the physical parameters. In this study, the results on the uptake and transportation of nutrients, which were obtained with the use of a positron-imaging method, are introduced.
