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Journal Articles

Sorption of Cs$$^{+}$$ and Eu$$^{3+}$$ ions onto sedimentary rock in the presence of gamma-irradiated humic acid

Zhao, Q.*; Saito, Takeshi*; Miyakawa, Kazuya; Sasamoto, Hiroshi; Kobayashi, Taishi*; Sasaki, Takayuki*

Journal of Hazardous Materials, 428, p.128211_1 - 128211_10, 2022/04

 Times Cited Count:0 Percentile:0.01(Engineering, Environmental)

The influence of humic acid and its radiological degradation on the sorption of Cs$$^{+}$$ and Eu$$^{3+}$$ by sedimentary rock was investigated to understand the sorption process of metal ions and humic substances. Aldrich humic acid (HA) solution was irradiated with different doses of gamma irradiation using a Co-60 gamma-ray source prior to the contact between the metal ions and the solid sorbent. The HA molecule decomposed to smaller molecules with a lower complexation affinity. Batch sorption experiments were performed to evaluate the effect of gamma-irradiated HA on the sorption of Cs$$^{+}$$ and Eu$$^{3+}$$ ions. The addition of non-irradiated HA weakened the sorption of Eu because of the lower sorption of the neutral or negatively charged Eu-HA complexes compared with free Eu ions. The sorption of monovalent Cs ions was barely affected by the presence of HA and its gamma irradiation. The concentration ratio of HA complexed species and non-complexed species in the solid and liquid phases was evaluated by sequential filtration and chemical equilibrium calculations. The ratios supported the minimal contribution of HA to Cs sorption. However, the concentration ratio for Eu$$^{3+}$$ in the liquid phase was high, indicating that the complexing ability of HA to Eu$$^{3+}$$ was higher than that of HA to Cs$$^{+}$$ ions. Therefore, the sorption of free Eu$$^{3+}$$ would predominate with the gamma irradiation dose applied to the HA solution under a radiation field near the HLW package.

JAEA Reports

Status of study of long-term assessment of transport of radioactive contaminants in the environment of Fukushima (FY2018) (Translated document)

Nagao, Fumiya; Niizato, Tadafumi; Sasaki, Yoshito; Ito, Satomi; Watanabe, Takayoshi; Dohi, Terumi; Nakanishi, Takahiro; Sakuma, Kazuyuki; Hagiwara, Hiroki; Funaki, Hironori; et al.

JAEA-Research 2020-007, 249 Pages, 2020/10

JAEA-Research-2020-007.pdf:15.83MB

The accident of the Fukushima Daiichi Nuclear Power Station, Tokyo Electric Power Company Holdings, Inc. occurred due to the Great East Japan Earthquake, Sanriku offshore earthquake, of 9.0 magnitude and the accompanying tsunami. As a result, large amount of radioactive materials was released into the environment. Under these circumstances, Japan Atomic Energy Agency (JAEA) has been conducting "Long-term Assessment of Transport of Radioactive Contaminants in the Environment of Fukushima" concerning radioactive materials released in environment, especially migration behavior of radioactive cesium since November 2012. This report is a summary of the research results that have been obtained in environmental dynamics research conducted by JAEA in Fukushima Prefecture.

Journal Articles

Numerical study of transport pathways of $$^{137}$$Cs from forests to freshwater fish living in mountain streams in Fukushima, Japan

Kurikami, Hiroshi; Sakuma, Kazuyuki; Malins, A.; Sasaki, Yoshito; Niizato, Tadafumi

Journal of Environmental Radioactivity, 208-209, p.106005_1 - 106005_11, 2019/11

AA2018-0485.pdf:1.87MB

 Times Cited Count:10 Percentile:53.44(Environmental Sciences)

To assess the uptake of Cs-137 ($$^{137}$$Cs) by freshwater fish, we developed a compartment model for the migration of $$^{137}$$Cs on the catchment scale from forests to river water. We modelled a generic forest catchment with Fukushima-like parameters to ascertain the importance of export pathways of $$^{137}$$Cs from forests to river water for the uptake of $$^{137}$$Cs by freshwater fish. The results suggest that the decreasing trend of $$^{137}$$Cs in river water and freshwater fish was due to combination of the decreasing trend in the forest leaves/needles and litter compartments, and the increasing trend in soil. The $$^{137}$$Cs concentrations within these forest compartments plateau at around ten years after the fallout due to $$^{137}$$Cs circulation in forests reaching an equilibrium state.

JAEA Reports

Status of study of long-term assessment of transport of radioactive contaminants in the environment of Fukushima (FY2018)

Nagao, Fumiya; Niizato, Tadafumi; Sasaki, Yoshito; Ito, Satomi; Watanabe, Takayoshi; Dohi, Terumi; Nakanishi, Takahiro; Sakuma, Kazuyuki; Hagiwara, Hiroki; Funaki, Hironori; et al.

JAEA-Research 2019-002, 235 Pages, 2019/08

JAEA-Research-2019-002.pdf:21.04MB

The accident of the Fukushima Daiichi Nuclear Power Station (hereinafter referred to 1F), Tokyo Electric Power Company Holdings, Inc. occurred due to the Great East Japan Earthquake, Sanriku offshore earthquake, of 9.0 magnitude and the accompanying tsunami. As a result, large amount of radioactive materials was released into the environment. Under these circumstances, JAEA has been conducting Long-term Environmental Dynamics Research concerning radioactive materials released in environment, especially migration behavior of radioactive cesium since November 2012. This report is a summary of the research results that have been obtained in environmental dynamics research conducted by JAEA in Fukushima Prefecture.

Journal Articles

Determination of dissolved natural thorium and uranium in Horonobe and Mizunami Underground Research Laboratory groundwater and its thermodynamic analysis

Sasaki, Takayuki*; Kokami, Takayuki*; Kobayashi, Taishi*; Kirishima, Akira*; Murakami, Hiroaki; Amano, Yuki; Mizuno, Takashi; Iwatsuki, Teruki; Sasamoto, Hiroshi; Miyakawa, Kazuya

Journal of Nuclear Science and Technology, 54(3), p.373 - 381, 2017/03

Trace amounts of natural thorium and uranium in deep groundwater were investigated at two underground research laboratories situated at Horonobe and Mizunami, Japan. The groundwater was sampled from underground boreholes, and the colloid contribution was checked by in situ two size-fractionated ultrafiltration systems. A decrease in the concentration after in situ filtration suggested the presence of natural colloids and suspended matter that were carriers of a portion of the elements. The result of the Th and U concentrations in groundwater after 10 kDa filtration was analyzed thermodynamically using existing hydrogeological and geochemical data such as the mineral components in the groundwater at a given pH, ionic strength, concentration of co-existing ions, redox potential, and solid phase assumed. A crystalline solid phase made the solubility very low compared with that of the amorphous phase, and the solubility agreed well with the concentrations measured.

Journal Articles

Nanoscopic structural investigation of physically cross-linked nanogels formed from self-associating polymers

Sekine, Yurina; Endo, Hitoshi*; Iwase, Hiroki*; Takeda, Shigeo*; Mukai, Sadaatsu*; Fukazawa, Hiroshi; Littrell, K. C.*; Sasaki, Yoshihiro*; Akiyoshi, Kazunari*

Journal of Physical Chemistry B, 120(46), p.11996 - 12002, 2016/11

 Times Cited Count:9 Percentile:29.02(Chemistry, Physical)

The detailed structure of a nanogel formed by self-association of cholesterol-bearing pullulans (CHP) was determined by contrast variation small-angle neutron scattering. The decomposition of scattering intensities into partial scattering functions of each CHP nanogel component, i.e., pullulan, cholesterol, and the cross-term between the pullulan and the cholesterol allows us to investigate the internal structure of the nanogel. The effective spherical radius of the skeleton formed by pullulan chains was found to be about 8.1 nm. In the CHP nanogel, there are about 19 cross-linking points where a cross-linking point is formed by aggregation of trimer cholesterol molecules with the spatially inhomogeneous distribution of the mass fractal dimension of 2.6. The average radius of the partial chains can also be determined to be 1.7 nm. As the result, the complex structure of the nanogels is coherently revealed at the nanoscopical level.

Journal Articles

Development of inspection and repair techniques for reactor vessel of experimental fast reactor "Joyo"; Replacement of upper core structure

Takamatsu, Misao; Kawahara, Hirotaka; Ito, Hiromichi; Ushiki, Hiroshi; Suzuki, Nobuhiro; Sasaki, Jun; Ota, Katsu; Okuda, Eiji; Kobayashi, Tetsuhiko; Nagai, Akinori; et al.

Nihon Genshiryoku Gakkai Wabun Rombunshi, 15(1), p.32 - 42, 2016/03

In the experimental fast reactor Joyo, it was confirmed that the top of the irradiation test sub-assembly of "MARICO-2" (material testing rig with temperature control) had been broken and bent onto the in-vessel storage rack as an obstacle and had damaged the upper core structure (UCS). This paper describes the results of the in-vessel repair techniques for UCS replacement, which are developed in Joyo. UCS replacement was successfully completed in 2014. In-vessel repair techniques for sodium cooled fast reactors (SFRs) are important in confirming its safety and integrity. In order to secure the reliability of these techniques, it was necessary to demonstrate the performance under the actual reactor environment with high temperature, high radiation dose and remained sodium. The experience and knowledge gained in UCS replacement provides valuable insights into further improvements for In-vessel repair techniques in SFRs.

Journal Articles

Model magnet development of D1 beam separation dipole for the HL-LHC upgrade

Nakamoto, Tatsushi*; Sugano, Michinaka*; Xu, Q.*; Kawamata, Hiroshi*; Enomoto, Shun*; Higashi, Norio*; Idesaki, Akira; Iio, Masami*; Ikemoto, Yukio*; Iwasaki, Ruri*; et al.

IEEE Transactions on Applied Superconductivity, 25(3), p.4000505_1 - 4000505_5, 2015/06

 Times Cited Count:0 Percentile:0(Engineering, Electrical & Electronic)

Recently, development of superconducting magnet system with high radiation resistance has been demanded for application in accelerator facilities such as CERN LHC. In order to realize superconducting magnet system with high radiation resistance, it is necessary to develop electrical insulator with high radiation resistance because the electrical insulator is made of organic materials whose radiation resistance is inferior to that of inorganic materials. We developed a glass fiber reinforced plastic with bismaleimide-triazine resin. The developed material showed excellent radiation resistance; the material evolved gases of 5$$times$$10 $$^{-5}$$mol/g and maintained flexural strength of 640MPa (90% of initial value).

Journal Articles

Shielding study at the Fukui Prefectural Hospital Proton Therapy Center

Satoh, Daiki; Maeda, Yoshikazu*; Tameshige, Yuji*; Nakashima, Hiroshi; Shibata, Tokushi*; Endo, Akira; Tsuda, Shuichi; Sasaki, Makoto*; Maekawa, Motokazu*; Shimizu, Yasuhiro*; et al.

Journal of Nuclear Science and Technology, 49(11), p.1097 - 1109, 2012/11

 Times Cited Count:10 Percentile:63.97(Nuclear Science & Technology)

At the Fukui Prefectural Hospital Proton Therapy Center, neutron doses behind concrete shields and at maze have been measured by using radiation monitors, DARWIN, Wendi-2, a rem meter, and solid state nuclear track detectors. The measured data were compared with the estimations by analytical models and Monte Carlo code PHITS. The analytical model with the parameters employed in shielding design of the facility gave considerably larger estimates than the measured data. This means that the facility was designed with an enough safety margin. The calculation results of PHITS were less than those of the analytical model, and were about 3 times larger than the measured data. From the view point of a safety policy with conservative estimation for shielding design, Monte Carlo simulation is a better tool for estimating radiation safety at accelerator-based proton treatment facilities.

Journal Articles

Systematic measurement of lineal energy distributions for proton, He and Si ion beams over a wide energy range using a wall-less tissue equivalent proportional counter

Tsuda, Shuichi; Sato, Tatsuhiko; Takahashi, Fumiaki; Satoh, Daiki; Sasaki, Shinichi*; Namito, Yoshihito*; Iwase, Hiroshi*; Ban, Shuichi*; Takada, Masashi*

Journal of Radiation Research, 53(2), p.264 - 271, 2012/04

 Times Cited Count:12 Percentile:54.92(Biology)

Deposit energy distribution in microscopic site is basic information for understanding of biological effects of energetic heavy ion beams. To estimate RBE, lineal energy, $$y$$, can be an appropriate physical index. In this work, a wall-less tissue equivalent proportional counter has been designed and used for the measurement of $$y$$ distributions, $$y$$$$f$$($$y$$), for 160 MeV H, 150 MeV/u He, 290 MeV/u C, 490 MeV/u Si and 500 MeV/u Ar. Data of $$y$$$$f$$($$y$$) were also obtained in the wide range of LET. The dose-means of $$y$$, $$overline{y}$$$$_{D}$$, were compared with those calculated by the microdosimetric function of PHITS. It is found that the calculated $$y$$$$f$$($$y$$) and $$overline{y}$$$$_{D}$$ agree fairly well with those measured. The values of $$overline{y}$$$$_{D}$$ are larger than those of LET less than $$sim$$10 keV/$$mu$$m because of the discrete energy deposition by delta rays, while the relation is reversed above 10 keV/$$mu$$m. The results indicate that care should be taken in the difference between $$overline{y}$$$$_{D}$$ and LET when the values of RBE of energetic heavy ions are estimated.

JAEA Reports

Conceptual design of multipurpose compact research reactor; Annual report FY2010 (Joint research)

Imaizumi, Tomomi; Miyauchi, Masaru; Ito, Masayasu; Watahiki, Shunsuke; Nagata, Hiroshi; Hanakawa, Hiroki; Naka, Michihiro; Kawamata, Kazuo; Yamaura, Takayuki; Ide, Hiroshi; et al.

JAEA-Technology 2011-031, 123 Pages, 2012/01

JAEA-Technology-2011-031.pdf:16.08MB

The number of research reactors in the world is decreasing because of their aging. However, the planning to introduce the nuclear power plants is increasing in Asian countries. In these Asian countries, the key issue is the human resource development for operation and management of nuclear power plants after constructed them, and also the necessity of research reactor, which is used for lifetime extension of LWRs, progress of the science and technology, expansion of industry use, human resources training and so on, is increasing. From above backgrounds, the Neutron Irradiation and Testing Reactor Center began to discuss basic concept of a multipurpose low-power research reactor for education and training, etc. This design study is expected to contribute not only to design tool improvement and human resources development in the Neutron Irradiation and Testing Reactor Center but also to maintain and upgrade the technology on research reactors in nuclear power-related companies. This report treats the activities of the working group from July 2010 to June 2011 on the multipurpose low-power research reactor in the Neutron Irradiation and Testing Reactor Center and nuclear power-related companies.

Journal Articles

Measurement of lineal energy distribution of heavy ion using wall-less tissue equivalent proportional counter

Tsuda, Shuichi; Sato, Tatsuhiko; Takahashi, Fumiaki; Satoh, Daiki; Sasaki, Shinichi*; Namito, Yoshihito*; Iwase, Hiroshi*; Ban, Shuichi*; Takada, Masashi*

KEK Proceedings 2011-8, p.100 - 108, 2011/12

Deposit energy distribution in microscopic site is basic information for understanding of biological effects of energetic heavy ion beams. To estimate RBE, lineal energy, y, can be an appropriate physical index. In this work, a wall-less tissue equivalent proportional counter has been designed and used for the measurement of y distributions, $$yf(y)$$, for 160 MeV H, 150 MeV/u He and 490 MeV/u Si ion beams. Data of $$yf(y)$$ and the dose-means of $$y$$, $$overline{y}_D$$, were compared with those calculated by the microdosimetric function of PHITS. It is found that the calculated $$yf(y)$$ and $$overline{y}_D$$ agree fairly well with those measured, as well as the already reported result of 290 MeV/u carbon beam.

Journal Articles

Management of cosmic radiation exposure for aircraft crew in Japan

Yasuda, Hiroshi*; Sato, Tatsuhiko; Yonehara, Hidenori*; Kosako, Toshiso*; Fujitaka, Kazunobu*; Sasaki, Yasuhito*

Radiation Protection Dosimetry, 146(1-3), p.123 - 125, 2011/07

 Times Cited Count:13 Percentile:72.72(Environmental Sciences)

The National Institute of Radiological Sciences (NIRS) has helped the airlines companies to follow the guideline, particularly for the calculation of aviation route doses. The presentation will show the annual individual doses of aircraft crew calculated for the 2007 fiscal year.

Journal Articles

Analysis of the effect of structural materials in a wall-less tissue-equivalent proportional counter irradiated by 290 MeV u$$^{-1}$$ carbon beam

Tsuda, Shuichi; Sato, Tatsuhiko; Takahashi, Fumiaki; Satoh, Daiki; Endo, Akira; Sasaki, Shinichi*; Namito, Yoshihito*; Iwase, Hiroshi*; Ban, Shuichi*; Takada, Masashi*

Radiation Protection Dosimetry, 143(2-4), p.450 - 454, 2011/02

 Times Cited Count:5 Percentile:41.32(Environmental Sciences)

A wall-less tissue equivalent proportional counter, wall-less TEPC, has been designed and used for the measurement of the y distributions for energetic heavy ions in order to verify a biological dose calculation model incorporated in the PHITS code. It is found that the dose-mean value of y obtained by the wall-less TEPC is 50 - 60% of the LET of the argon ions in water, since the delta-rays with relatively low y can be measured.

Journal Articles

Measurement of microdosimetric spectra with a wall-less tissue-equivalent proportional counter for 290 MeV/u $$^{12}$$C beam

Tsuda, Shuichi; Sato, Tatsuhiko; Takahashi, Fumiaki; Satoh, Daiki; Endo, Akira; Sasaki, Shinichi*; Namito, Yoshihito*; Iwase, Hiroshi*; Ban, Shuichi*; Takada, Masashi*

Physics in Medicine & Biology, 55(17), p.5089 - 5101, 2010/09

 Times Cited Count:21 Percentile:59.14(Engineering, Biomedical)

The frequency distribution of the lineal energy of 290 MeV/u carbon beam was measured using a wall-less tissue equivalent proportional counter (wall-less TEPC) in a cylindrical volume with simulated diameter 0.72 $$mu$$m in verifying the accuracy of a dose calculation model. The measured lineal energy distribution as well as its dose-mean value agreed fairly well with the corresponding data from microdosimetric calculations using the PHITS code within the experimental uncertainty. It is found that a wall-less TEPC is needed to measure the precise energy deposition spectra of the delta rays produced secondarily by energetic heavy ion beams. The measured data also indicate that more than 11% of the energy escaped from the path of the trajectory of the carbon beam.

Journal Articles

Recent progress in the energy recovery linac project in Japan

Sakanaka, Shogo*; Akemoto, Mitsuo*; Aoto, Tomohiro*; Arakawa, Dai*; Asaoka, Seiji*; Enomoto, Atsushi*; Fukuda, Shigeki*; Furukawa, Kazuro*; Furuya, Takaaki*; Haga, Kaiichi*; et al.

Proceedings of 1st International Particle Accelerator Conference (IPAC '10) (Internet), p.2338 - 2340, 2010/05

Future synchrotron light source using a 5-GeV energy recovery linac (ERL) is under proposal by our Japanese collaboration team, and we are conducting R&D efforts for that. We are developing high-brightness DC photocathode guns, two types of cryomodules for both injector and main superconducting (SC) linacs, and 1.3 GHz high CW-power RF sources. We are also constructing the Compact ERL (cERL) for demonstrating the recirculation of low-emittance, high-current beams using above-mentioned critical technologies.

Journal Articles

Measurement of lineal energy distribution by a wall-less tissue equivalent proportional counter for heavy ion beams

Tsuda, Shuichi; Sato, Tatsuhiko; Takahashi, Fumiaki; Satoh, Daiki; Endo, Akira; Sasaki, Shinichi*; Namito, Yoshihito*; Iwase, Hiroshi*; Ban, Shuichi*; Takada, Masashi*

KEK Proceedings 2009-12, p.36 - 44, 2010/01

Knowledge of energy deposition at micrometer dimensions along heavy ion tracks is essential to understand the biological effects of radiation. Wall-less tissue equivalent proportional counter (wall-less TEPC) was produced for the purpose of measurement of lineal energy distribution including secondary-produced high-energy electrons, delta-rays. The measurement using the wall-less TEPC was performed at Heavy Ion Medical Accelerator at NIRS, Japan. It is found that lineal energy distributions could be measured for primary carbon beam with energy of 400MeV per nucleon and delta-rays. Detail of the experiment, energy calibration and estimation of delta-rays production will be presented.

Journal Articles

Evaluation of delta-rays production in a wall-less tissue equivalent proportional counter irradiated by energetic heavy ion beams

Tsuda, Shuichi; Sato, Tatsuhiko; Iwase, Hiroshi*; Namito, Yoshihito*; Sasaki, Shinichi*

KEK Proceedings 2009-6, p.90 - 95, 2009/11

Deposit energy distributions of secondary high-energy electrons, delta-rays, have been calculated in a wall/wall-less tissue equivalent proportional counter, TEPC, using Monte Carlo simulation code EGS5. It is found that wall-less TEPCs are indispensable for lineal energy distribution in tissue equivalent gas irradiated by energetic heavy ion beams.

Journal Articles

High-precision measurement of the spectral width of the nickel-like molybdenum X-ray laser

Hasegawa, Noboru; Kawachi, Tetsuya; Sasaki, Akira; Yamatani, Hiroshi; Kishimoto, Maki; Ochi, Yoshihiro; Tanaka, Momoko; Nishikino, Masaharu; Kunieda, Yuichi; Nagashima, Keisuke; et al.

Journal of Physics; Conference Series, 163(1), p.012062_1 - 012062_4, 2009/06

 Times Cited Count:2 Percentile:67.98

The precise knowledge about the wavelength and the spectral width of the lasing line is important for the applications of X-ray lasers, and especially for the spectral width, it is good benchmark of the atomic code because it depends on the electron collisional excitation and de-excitation rate coefficient. Only a few measurements of the spectral width of the laser line have been reported, because the spectral width of the X-ray laser is so narrow that the required spectral resolution is quite high. In this study, we took the nickel-like molybdenum X-ray laser as an example, and measure the spectral width by use of the high resolution spectrometer in order to compare it with a theoretical one.

JAEA Reports

Evaluation method of pH elevation due to reaction between hydrates of ordinary Portland cement and saline groundwater

Masuda, Kenta; Oda, Chie; Nakanishi, Hiroshi*; Sasaki, Ryoichi*; Takase, Toshio*; Akagi, Yosuke*; Fujita, Hideki*; Negishi, Kumi*; Honda, Akira

JAEA-Research 2008-104, 194 Pages, 2009/03

JAEA-Research-2008-104.pdf:9.43MB

Saline groundwater contains high concentrations of chloride ions, which possibly elevate the pH of cement pore water by reacting with hydrogarnet and producing Friedel's salt. Calcium aluminate hydrates and portlandite, which can be found in hydrated ordinary Portland cement (OPC), were immersed in a sodium chloride solution, which had concentrations similar to those found in seawater.

103 (Records 1-20 displayed on this page)