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JAEA Reports

Applicability evaluation of Type A transport container for off-site transportation of small-amount of fuel debris

Sakamoto, Masahiro; Okumura, Keisuke; Kanno, Ikuo; Matsumura, Taichi; Terashima, Kenichi; Riyana, E. S.; Mizokami, Masato*; Mizokami, Shinya*

JAEA-Research 2024-017, 14 Pages, 2025/03

JAEA-Research-2024-017.pdf:1.34MB

In the TEPCO's Fukushima Daiichi Nuclear Power Station (1F), a trial retrieval of fuel debris with small-amount from Unit 2 is planned. The retrieved fuel debris will be transported out of 1F to Institutes in Ibaraki prefecture for analysis. The analyzed results will be utilized for the improvement of the processes (retrieval, transportation and storage) in the fuel debris management as feedback, and also for the development of technologies necessary in the future. The weight of fuel debris in the trial retrieval is planned to be a few grams. After the trial, the scale of retrieval will be expanded step by step. In the trial retrieval, a rational transportation container should be considered beforehand, according to the laws and regulations associated with the off-site transportation. The transportation container has a classification and the classification is decided according to the radioactivity of the material in the container. In this report, we evaluated the applicability of the Type A transport container to contribute to the safety assessment of retrieved fuel debris.

Journal Articles

Characterization of neutrons emitted by an expected small amount of fuel debris in a trial retrieval from Fukushima Daiichi Nuclear Power Station

Matsumura, Taichi; Okumura, Keisuke; Sakamoto, Masahiro; Terashima, Kenichi; Riyana, E. S.; Kondo, Kazuhiro*

Nuclear Engineering and Design, 432, p.113791_1 - 113791_9, 2025/02

 Times Cited Count:0 Percentile:0.00(Nuclear Science & Technology)

Journal Articles

Development of a theoretical scaling factor method for the inventory estimation of difficult-to-measure nuclide Cs-135 in fuel debris and radioactive wastes

Sakamoto, Masahiro; Okumura, Keisuke; Kanno, Ikuo; Matsumura, Taichi; Terashima, Kenichi; Riyana, E. S.; Kaneko, Junichi*; Mizokami, Masato*; Mizokami, Shinya*

Journal of Nuclear Science and Technology, 10 Pages, 2025/00

 Times Cited Count:0 Percentile:0.00(Nuclear Science & Technology)

Journal Articles

Activation level of the concrete building and pressure vessel in JAEA-Tokai tandem accelerator

Yoshida, Go*; Matsumura, Hiroshi*; Nakamura, Hajime*; Miura, Taichi*; Toyoda, Akihiro*; Masumoto, Kazuyoshi*; Nakabayashi, Takayuki*; Matsuda, Makoto

Journal of Nuclear Science and Technology, 61(10), p.1298 - 1307, 2024/10

 Times Cited Count:0 Percentile:0.00(Nuclear Science & Technology)

Journal Articles

Preliminary study of the criticality monitoring method based on the simulation for the activity ratio of short half-life noble-gas fission products from fuel debris

Riyana, E. S.; Okumura, Keisuke; Sakamoto, Masahiro; Matsumura, Taichi; Terashima, Kenichi; Kanno, Ikuo

Journal of Nuclear Science and Technology, 61(2), p.269 - 276, 2024/02

 Times Cited Count:0 Percentile:0.00(Nuclear Science & Technology)

Journal Articles

Characterization of bremsstrahlung and $$gamma$$-rays of fuel debris

Matsumura, Taichi; Okumura, Keisuke; Fujita, Manabu*; Sakamoto, Masahiro; Terashima, Kenichi; Riyana, E. S.

Radiation Physics and Chemistry, 199, p.110298_1 - 110298_8, 2022/10

 Times Cited Count:3 Percentile:41.50(Chemistry, Physical)

Journal Articles

Depletion calculation of subcritical system with consideration of spontaneous fission reaction

Riyana, E. S.; Okumura, Keisuke; Sakamoto, Masahiro; Matsumura, Taichi; Terashima, Kenichi

Journal of Nuclear Science and Technology, 59(4), p.424 - 430, 2022/04

 Times Cited Count:1 Percentile:9.64(Nuclear Science & Technology)

Journal Articles

Comparison of photon spectra emitted from fuel debris using different decay data libraries

Matsumura, Taichi; Okumura, Keisuke; Fujita, Manabu*

JAEA-Conf 2021-001, p.144 - 149, 2022/03

We require reliable nuclear data that can appropriately evaluate the radiation characteristics of fuel debris for the purpose such as development of new sensors, non-destructive assay technologies and optimization of radiation shielding. In the past, even if different results were obtained depending on calculation codes, it was difficult to clarify what caused the differences. To overcome it, we have developed a new reliable code to calculate radiation decay and radioactive source spectra that can accurately treat with large amounts of nuclides and all decay modes in the decay data file. As the first step, we compared the photon spectra of fuel debris by using the recent decay data files: JENDL/DDF-2015, decay sub-libraries of ENDF/B-VIII.0 and JEFF-3.3. In the presentation, we will report requests for the modifications on the decay scheme and branching ratio of decay mode for the next JENDL decay data file.

Journal Articles

Gamma detector response simulation inside the pedestal of Fukushima Daiichi Nuclear Power Station

Riyana, E. S.; Okumura, Keisuke; Terashima, Kenichi; Matsumura, Taichi; Sakamoto, Masahiro

Mechanical Engineering Journal (Internet), 7(3), p.19-00543_1 - 19-00543_8, 2020/06

Journal Articles

Evaluation of energy spectrum around structural materials in radiation environments

Matsumura, Taichi; Nagaishi, Ryuji; Katakura, Junichi*; Suzuki, Masahide*

Radiation Physics and Chemistry, 166, p.108493_1 - 108493_9, 2020/01

 Times Cited Count:2 Percentile:17.49(Chemistry, Physical)

In this work, when radiation sources of $$^{137}$$Cs, $$^{90}$$Sr and $$^{90}$$Y were assumed to be put in the front of a plain SUS304 plate as a typical material submerged in water, energy spectra of secondary photons and electrons at the front and back sides of plate were simulated with changing the thickness of plate, and spacing between the source and plate by using a Monte Carlo calculation code of PHITS. In the case of $$^{137}$$Cs gamma-ray (monochromatic 662 keV), the energy spectra at the front side was smaller than those at the back side due to the existence of plate. Then the dependence of spectra on the plate thickness was observed more clearly at the back side than at the front side. It was clearly shown how the energy spectra of photons and electrons varied with the incident radiation type, the spacing, and the thickness.

Journal Articles

Analytical studies of three-dimensional evaluation of radionuclide distribution in zeolite wastes through gamma scanning of adsorption vessels

Matsumura, Taichi; Nagaishi, Ryuji; Katakura, Junichi*; Suzuki, Masahide*

Nuclear Science and Engineering, 192(1), p.70 - 79, 2018/10

 Times Cited Count:1 Percentile:9.77(Nuclear Science & Technology)

The gamma-scanning of SDS (submerged demineralizer system) vessel used as a typical vessel for decontamination of radioactive water at Three Mile Island Unit 2 (TMI-2) accident was simulated in the axial and radial directions of real and cylindrical-shaped vessels by using a Monte Carlo calculation code (PHITS) on the basis of the geometrical and compositional information of vessel and gamma-scanning available in the previous reports at the accident. In the axial simulation, the true distribution of radioactive $$^{137}$$Cs in the zeolite packed bed of vessel was successfully evaluated when a correction function derived from a virtual constant distribution of $$^{137}$$Cs was applied to the reported gamma-scanning profile. In the radial simulation, the virtual disk-formed and shell-formed sources of $$^{137}$$Cs displaced in the packed bed were clearly observed from the top and bottom views of vessel. This new radial gamma-scanning indicates that the radial localization of $$^{137}$$Cs could be well observed by measuring gamma-ray from the top view of vessel during storage. We further examined the radial gamma-scanning from the side view whether the radial localization of $$^{137}$$Cs can be confirmed in the normally existing gamma-scanning room or not.

Journal Articles

Summary of study on environmental radioactivity effected from the accident at the TEPCO Fukushima Daiichi Nuclear Power Plant in 5 years after the accident

Iimoto, Takeshi*; Kinoshita, Norikazu*; Sakaguchi, Aya*; Sugihara, Shinji*; Takamiya, Koichi*; Tagami, Keiko*; Nagao, Seiya*; Bessho, Kotaro*; Matsumura, Hiroshi*; Miura, Taichi*; et al.

KEK Report 2016-3, 134 Pages, 2017/03

This report is summary of study on environmental radioactivity effected from the accident at the TEPCO Fukushima Daiichi Nuclear Power Plant in 5 years after the accident. It was compiled efforts related to the accident reported from the 13th to the 17th "Workshop on Environmental Radioactivity" which was held at the High Energy Accelerator Research and Development Organization.

Oral presentation

Development of theoretical scaling factor method for $$^{135}$$Cs caused by the Fukushima Daiichi NPP accident

Terashima, Kenichi; Sakamoto, Masahiro; Matsumura, Taichi; Okumura, Keisuke; Fujita, Manabu*

no journal, , 

no abstracts in English

Oral presentation

Development of nuclear fuel material evaluation method using integral dosimeter; Basic data acquisition of babble detector

Terashima, Kenichi; Kaburagi, Masaaki; Sakamoto, Masahiro; Matsumura, Taichi; Fujita, Manabu*; Okumura, Keisuke

no journal, , 

Bubble detector (BD) is neutron integral dosimeter with advantages of insensitivity to gamma ray, no power supply, visual confirmation and controllability of irradiation time according to neutron flux. Therefore, application of detection and nondestructive measurement for fuel debris is expected at Fukushima Daiichi Nuclear Power Station. Then, basic data of babble detector obtained by neutron irradiation experiment for applicability evaluation of BD.

Oral presentation

Dose evaluation of adsorption vessels for contaminated water treatment by using radiation transport and shielding calculation codes

Matsumura, Taichi; Nagaishi, Ryuji; Katakura, Junichi*; Suzuki, Masahide*

no journal, , 

no abstracts in English

Oral presentation

Oral presentation

Studies on water radiolysis under irradiation of X-ray simulating bremsstrahlung, 2; Evaluation of effect of radiation quality on molecular formation

Nagaishi, Ryuji; Kuwano, Ryo*; Matsumura, Taichi

no journal, , 

Different from monochromatic photons such as Co-60 $$gamma$$-rays, Bremsstrahlung and X-rays with continuous energies provide photons with different radiation quality (RQ) into water, dependent on the width of water layer. Since the photons with different RQ further give different primary yields (G-value) of water radiolysis, the effect of RQ (LET) on G-values would be important in experiments with photons with continuous energies. In this study, the experiments using X-rays simulating Bremsstrahlung from $$beta$$-ray and secondary electrons were conducted with changing the tube voltage and water width to clarify the LET effect on the X-ray radiolysis of water.

Oral presentation

Consideration of water radiolysis in void volumes of porous zeolite bed loaded in adsorption vessels for decontamination of radioactive water

Nagaishi, Ryuji; Inoue, Masao; Matsumura, Taichi; Yamagishi, Isao; Hino, Ryutaro; Ogawa, Toru

no journal, , 

Hydrogen gas generation in radiolysis of pure water or seawater coexisting with zeolite adsorbents has been investigated by using Co-60 $$gamma$$-ray for hydrogen safety in decontamination of radioactive water after Fukushima Daiichi NPS accident. In this work, two types of void volumes present in the zeolite bed were paid attention microscopically, and the difference in water radiolysis between the volumes was considered. The oxygen generated by decomposition of hydrogen peroxide, as the counterpart of hydrogen molecule, contacting with the zeolites were also discussed.

Oral presentation

Irradiation experiments of simulated carbonate slurry in HIC, 3; Studies on radiolysis behavior of simulated carbonate slurry

Nagaishi, Ryuji; Motooka, Takafumi; Yamagishi, Isao; Inoue, Masao; Matsumura, Taichi

no journal, , 

no abstracts in English

Oral presentation

Estimation of thermal decomposition rates of hydrogen peroxide in aqueous solution systems of coexisting solid materials

Nagaishi, Ryuji; Kuwano, Ryo*; Inoue, Masao*; Matsumura, Taichi

no journal, , 

no abstracts in English

49 (Records 1-20 displayed on this page)