Search

Your search keyword '"Rei Kimura"' showing total 19 results
Start Over Author "Rei Kimura"
19 results on '"Rei Kimura"'

1. Fade-out time shortening on radiotoxicity and decay heat using TRU generation reduction fuel

Author

Kouji HIRAIWA, Rei KIMURA, Satoshi WADA, Tsukasa SUGITA, Kenichi YOSHIOKA, Satoshi TAKEDA, and Takanori KITADA

Subjects
trans uranium (tru), radiotoxicity, high level waste (hlw), spent nuclear fuel (snf), decay heat, high assay low enriched uranium (haleu), advanced boiling water reactor (abwr), partitioning and transmutation (p&t), fission product (fp), Mechanical engineering and machinery, TJ1-1570
Abstract

We analyzed the possibility of TRU generation reduction fuel using HALEU as the initial enrichment to reduce the radiotoxicity and decay heat of TRU when using the LWR fuels that can suppress radiotoxicity and decay heat in HLW. Fade-out time was defined as the period required to decay to the level of natural uranium ore, focusing on the radiotoxicity, and decay heat up to one million years, which is generated from the reduced TRU generation type fuel (FORSETI) consisting of uranium fuel of HALEU enrichment. The decay characteristics of TRU nuclides in HLW after plutonium removal by reprocessing and the effect of shortening the fade-out time were mainly discussed. The level of 241Am on both radiotoxicity and decay heat is significant. However, the effect of 239Pu and 240Pu, which are produced as daughter nuclides of 243Am and 244Cm after reprocessing, significantly lengthens the fade-out time to 100,000 years for radiotoxicity and to 40,000 years for decay heat, compared to several thousand years for 241Am alone. When TRU generation reduction fuel is adopted, the production rate of 243Am and 244Cm is reduced by more than 90% when the enrichment is increased from 3.8 wt% to 20 wt%, and the generation of 239Pu and 240Pu as daughter nuclides are also reduced almost correspondingly. As a result, increasing the initial 235U enrichment from 3.8 wt% to 20 wt% reduces the fade-out time of radiotoxicity from 100,000 to 3,000 years and the fade-out time of decay heat from 40,000 to 2,000 years for HLW, respectively by FORSETI-type TRU generation reduction fuel. As described above, it is shown that using TRU generation reduction fuel can significantly accelerate the decay of TRU radiotoxicity and decay heat in HLW without transmutation of TRU.

Published
2023
Full Text
View/download PDF

2. Relationship between a history of disabled throwing shoulder/elbow and the ability to perform the deep squat test among youth baseball players

Author

Hideaki Nagamoto, Takayuki Muraki, Shimpei Takahashi, Rei Kimura, Hiroaki Ishikawa, Kiyotsugu Shinagawa, Shunsuke Matsuoka, Yoshiyasu Yamada, Haruki Yaguchi, Daisuke Kurokawa, Hiroyuki Takahashi, and Tsukasa Kumai

Subjects
Disabled throwing shoulder, Disabled throwing elbow, Deep squat test, Lower extremity function, Kinetic chain, Orthopedic surgery, RD701-811
Abstract

Aim: The deep squat test (DST) is a screening test to assess the function of the lower extremity and the flexibility of ankle dorsiflexion. Previous study reported that approximately 70% of players with disabled throwing shoulder and/or elbows were unable to perform DST. The aim of this study was to reveal the relationship between performance of DST and history of disabled throwing shoulder/elbow. Methods: A total of 1,439 youth baseball players (10.9 years; range 6–16 years), who participated in pre-season medical examination were included in the study. Players who experienced shoulder or elbow pain of the throwing side during or after playing baseball in the past were defined as players with a history of disabled throwing shoulder/elbow. The DST was evaluated by having the players perform a full squat with while having their arms crossed in front of their chest and their feet apart without lifting the heel off the floor or falling backwards. The relationship between a history of disabled throwing shoulder/elbow and the ability to perform DST was analyzed. Results: Among the study participants, 499 (34.7%) had a history of disabled throwing shoulder/elbow, and 532 players (37.0%) were unable to perform DST. Of the players with disabled throwing shoulder/elbow history, 227 players (45.5%) were unable to perform DST, as were 305 players out of 940 players (32.5%) without a disability; this difference was statistically significant (P

Published
2023
Full Text
View/download PDF

3. Study on the flow and heat transport characteristics of concentric-tube two-phase thermosyphon

Author

Takuya HONGO, Yuki MIYACHI, Rei KIMURA, Hideki HORIE, Tomonao TAKAMATSU, and Chikako IWAKI

Subjects
heat transfer, flow observation, thermosyphon, two-phase, concentric-tube, Mechanical engineering and machinery, TJ1-1570
Abstract

Two-phase thermosyphons, which use sodium at 960 K as a refrigerant for heat transportation in small nuclear reactors, are promising for manned exploration to Mars. This is because the concentric-tube type thermosyphon may not have a flooding limit, and so the heat transfer performance per unit volume is comparatively large. Moreover, since its external form is a single tube by inserting a pipe through which the liquid flows into a pipe through which the gas flows, the reactor core can be made smaller. Experimental investigations of heat transport characteristics using water, R113, ethanol, and nitrogen as refrigerants and development of prediction formulas are progressing for establishing the design of the concentric-tube two-phase thermosyphon. However, it is necessary to use sodium at 960 K for application to heat transportation of a reactor, and further elucidation of the flow phenomenon is necessary to establish its performance prediction model. We have proposed a model based on bubble pump theory in order to take into consideration the rise of liquid level of the heating section. We conducted an experimental study on the flow inside a thermosyphon made of transparent material, and evaluated the maximum heat transfer rate using a low boiling point refrigerant, HFE-7100. As a result, even when the heat transfer rate was close to the maximum, it was shown that the flow regime in the outer tube of the adiabatic section of the concentric tube is two-phase flow. However, the experimental value of the maximum heat transfer rate was found to be about 17 % smaller than the calculated value. We therefore investigated the cause of this difference by making pressure measurements and flow observations, and found that bubble entrainment in the inner tube of the concentric tube of the adiabatic section greatly influences the pressure distribution. It is thought that taking mixing into consideration would help improve the model.

Published
2020
Full Text
View/download PDF

7. Reactor Core Power Distribution Reconstruction Method by Ex-Core Detectors Based on the Correlation Effect Between Fuel Regions

Author

Satoshi Wada, Yuki Nakai, and Rei Kimura

Subjects
Core (optical fiber), Distribution (mathematics), Materials science, Nuclear Energy and Engineering, Nuclear reactor core, Nuclear engineering, Detector, ComputerApplications_COMPUTERSINOTHERSYSTEMS, Physics::Chemical Physics, Microreactor, Reconstruction method, Power (physics)
Abstract

A novel ex-core-detector–based core power reconstruction method is presented. The method uses power correlations between fuel regions and can be applied to a real-time small reactor core monitoring...

Published
2021
Full Text
View/download PDF

8. Passive Reactivity Control Device with Thermal Expansion of Liquid In-Gd Alloy

Author

Shohei Kanamura, Takahashi Yuya, Kazuhito Asano, and Rei Kimura

Subjects
Nuclear and High Energy Physics, Liquid metal, Materials science, 020209 energy, Nuclear engineering, Alloy, Thermal power station, 02 engineering and technology, engineering.material, Condensed Matter Physics, Thermal expansion, Small modular reactor, 020303 mechanical engineering & transports, 0203 mechanical engineering, Nuclear Energy and Engineering, 0202 electrical engineering, electronic engineering, information engineering, engineering, Reactivity (chemistry), Energy source, Realization (systems)
Abstract

The small modular reactor (SMR) is considered one of the important energy sources for the realization of the de-carbonated society, especially SMR types that have 10 MW or less thermal power, calle...

Published
2021
Full Text
View/download PDF

9. Disabled throwing shoulder/elbow players have high rates of impaired foot function

Author

Hideaki Nagamoto, Rei Kimura, Eri Hata, and Tsukasa Kumai

Subjects
Physical Therapy, Sports Therapy and Rehabilitation, Orthopedics and Sports Medicine
Abstract

The prevalence of impaired foot function and floating toes of 91 baseball players with disabled throwing shoulder or elbow were retrospectively investigated. Foot function was evaluated by foot "rock paper scissors" and floating toes were confirmed if none of the toes made contact with the mat in standing posture. The prevalence of impaired foot function and floating toes and the relationship between between them were determined. Abnormal foot function was observed in 83 players (91%); of those, 73 players (88%) also had floating toes, and the prevalence was statistically significant compared to those without it (12%) (

Published
2022

10. Rotation-related sports players demonstrate rotation-type lumbar spondylolysis fracture angle and decreased hip internal rotation range of motion

Author

Akira Oizumi, Yu Konashi, Masaya Abe, Hideaki Nagamoto, Mitsuhiro Takahashi, and Rei Kimura

Subjects
Orthodontics, business.industry, Internal rotation, food and beverages, Level iv, Spondylolysis, medicine.disease, Rotation, Trunk, Article, Lumbar, Fracture (geology), Medicine, Orthopedics and Sports Medicine, Range of motion, business, human activities
Abstract

Relationship between sports and spondylolysis fracture angle (SFA), and hip internal rotation range of motion (IR ROM) between the sports groups among athletes with spondylolysis were investigated. Sports requiring repeated rotation of the trunk and hips during most aspects of the activity was defined as rotation-related sports (RRS). The SFA was defined as rotation-type or horizontal-type by using the axial view of the CT scan. Percentage of rotation type and SFA of the non-dominant side for RRS group was significantly greater than those of non-RRS group. Hip IR ROM of RRS group was significantly smaller than that of non-RRS group. Level of evidence Level IV.

Published
2021

11. Ensuring Criticality Safety of vSMR Core During Transport Based on Its Temperature Reactivity

Author

Rei Kimura and Kazuhito Asano

Subjects
Fukushima daiichi, Nuclear Energy and Engineering, Criticality, Nuclear engineering, Environmental science, Sustainable energy
Abstract

Nuclear energy has been one of the sustainable energy sources, but after the Fukushima Daiichi nuclear accident, large-scale light water reactors are losing price competitiveness due to the...

Published
2019
Full Text
View/download PDF

12. Temperature Reactivity Control of Calcium Hydride–Moderated Small Reactor Core with Poison Nuclides

Author

Satoshi Wada and Rei Kimura

Subjects
Materials science, Calcium hydride, 010308 nuclear & particles physics, Nuclear engineering, 0211 other engineering and technologies, 02 engineering and technology, 01 natural sciences, Small modular reactor, chemistry.chemical_compound, Nuclear Energy and Engineering, chemistry, Nuclear reactor core, 0103 physical sciences, Reactivity (chemistry), 021108 energy, Power output, Nuclide
Abstract

A small modular reactor (SMR) is a promising candidate for future nuclear energy; therefore, many organizations are developing SMRs. Some SMRs have a power output higher than 100 MW(electri...

Published
2019
Full Text
View/download PDF

14. Principle validation of nuclear fuel material isotopic composition measurement method based on photofission reactions

Author

Hiroshi Sagara, Rei Kimura, and Satoshi Chiba

Subjects
Nuclear and High Energy Physics, Measurement method, Photon, Nuclear fuel, Chemistry, 020209 energy, Photofission, 02 engineering and technology, Isotopic composition, Nuclear physics, Cross section (physics), Nuclear Energy and Engineering, Mathematical process, 0202 electrical engineering, electronic engineering, information engineering, Neutron
Abstract

We have developed a new nondestructive assay technique based on the photonuclear reaction, which is aimed at measuring the isotopic composition of nuclear fuel materials without relying on their self-generated neutron information. This methodology enables measurement of the number of neutrons produced by the photofission reactions at different specific photon energies, and only information on the relative counts and not the absolute values or energies, which are considerably affected by backgrounds, are required for the enrichment induction according to a mathematical process. The present methodology estimated the 235U enrichment value with 8% accuracy when the cross section uncertainty is 5%.

Published
2016

15. Design study of molten-salt-type reactor for powering space probes and its automated start-up

Author

Rei Kimura and Tadashi Yoshida

Subjects
Nuclear and High Energy Physics, Molten salt reactor, business.industry, Nuclear engineering, Energy conversion efficiency, NASA Deep Space Network, Nuclear reactor, law.invention, Solar battery, Nuclear Energy and Engineering, law, Environmental science, Electricity, Radioisotope thermoelectric generator, business, Nuclear power in space
Abstract

Space probes exploring the deep space need a noticeable amount of electricity for powering their instrumentation (5–8 kWe). The solar battery, however, is not able to afford this because of the extended distance between the probe and the sun. Furthermore, the radioisotope thermoelectric generator (RTG) may be extraordinarily sizable for this purpose. On the contrary, installation of nuclear reactor on the probes seems to be promising for the reasons such as its small mass, stability, and its high power density. Especially, the deep-space sample return mission has an essential demand for a nuclear reactor typically with the following specifications: 10-year reactor employment time, total system mass less than 500 kg, and electricity output more than 8 kWe. High power density is the key to realize these requirements. The thermal electricity conversion efficiency of a space reactor increases in accordance with the rise of the core temperature. Thus, in the present study, we propose a use of the molten-salt f...

Published
2013
Full Text
View/download PDF

16. Applicability Study of the Photofission Based Nuclear Material Isotopic Composition Measurement Method on the Thorium Uranium System

Author

Hiroshi Sagara, Rei Kimura, and Satoshi Chiba

Subjects
Reproducibility, Materials science, Nuclear fuel, 020209 energy, Radiochemistry, Photofission, chemistry.chemical_element, Thorium, 02 engineering and technology, Nuclear material, Uranium, Isotopic composition, chemistry, 0202 electrical engineering, electronic engineering, information engineering, Neutron
Abstract

A principle of new nondestructive assay (NDA) technique based on the photofission reaction ratio (PFRR) has been developed, which is aimed at measuring the isotopic composition of nuclear fuel materials without relying on their self-generated neutron information. The feasibility of the PFRR method was validated in the 235U-238U system previously. However, applicability of the PFRR method in the other material is not yet validated. In this study, applicability of PFRR method to the 232Th-233U system was confirmed, PFRR method showed good reproducibility of predicted value of 232Th and 233U isotopic composition.

Published
2016

17. Precision requirement of the photofission cross section for the nondestructive assay

Author

Hiroshi Sagara, Rei Kimura, and Satoshi Chiba

Subjects
Physics, Photon, 010308 nuclear & particles physics, QC1-999, 020209 energy, Photofission, 02 engineering and technology, Enriched uranium, 01 natural sciences, Nuclear physics, Cross section (physics), 0103 physical sciences, 0202 electrical engineering, electronic engineering, information engineering, Neutron, Nondestructive assay
Abstract

Principle of the new NDA technique based on the photofission reaction rate ratio (PFRR) has been developed by Kimura et al for measurement of uranium enrichment by using the only relative measured counts of neutron produced by photofission reactions of 235 U and 238 U at different specific incident photon energies. In the past analysis, no attentions have been paid for relatively large uncertainty of photonuclear cross section of special nuclear materials around 10%. In the present paper, quantitative analysis was performed to reveal the impact of photonuclear cross section uncertainty to predicted value of the uranium enrichment by the PFRR methodology. And also, the requirement of photofission cross section precision was evaluated as less than 3%, to satisfy the uncertainty of PFRR methodology to within 5%.

Published
2017
Full Text
View/download PDF

18. Precision requirement of the photofission cross section for the nondestructive assay.

Author

Rei Kimura, Hiroshi Sagara, and Satoshi Chiba

Subjects
*PHOTOFISSION, *NUCLEAR cross sections, *URANIUM, *PHOTONS, *PHOTONUCLEAR reactions
Abstract

Principle of the new NDA technique based on the photofission reaction rate ratio (PFRR) has been developed by Kimura et al for measurement of uranium enrichment by using the only relative measured counts of neutron produced by photofission reactions of 235U and 238U at different specific incident photon energies. In the past analysis, no attentions have been paid for relatively large uncertainty of photonuclear cross section of special nuclear materials around 10%. In the present paper, quantitative analysis was performed to reveal the impact of photonuclear cross section uncertainty to predicted value of the uranium enrichment by the PFRR methodology. And also, the requirement of photofission cross section precision was evaluated as less than 3%, to satisfy the uncertainty of PFRR methodology to within 5%. [ABSTRACT FROM AUTHOR]

Published
2017
Full Text
View/download PDF

19. Rosa de Japon

Author

Rei Kimura, Rei Kimura, Rei Kimura, and Rei Kimura

Abstract

Sayuri Miyamoto deja atrAs su adolescencia en una aldea japonesa para adentrarse en el Tokio de la Segunda Guerra Mundial. El duro trabajo como enfermera llena su corazOn de rabia y de patriotismo. Y ni los remordimientos que acompaNan sus noches ni el hecho de ser mujer le impiden tomar la identidad de su hermano e ingresar en el cuerpo de pilotos kamikazes. SerA allI donde conozca dos sentimientos que, en esos tiempos, van de la mano: el amor y la muerte. Medio siglo despuEs, la historiadora Mayumi Onodera recibe el encargo de averiguar si realmente existiO esta mujer y, en tal caso, investigar la forma en que logrO burlar los estrictos cOdigos japoneses.

Catalog

Books, media, physical & digital resources
See catalog results