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Hirose, Yoshiyasu; Kukita, Yutaka; Shibamoto, Yasuteru; Sagawa, Jun*
Proceedings of 19th International Topical Meeting on Nuclear Reactor Thermal Hydraulics (NURETH-19) (Internet), 12 Pages, 2022/03
Hirose, Yoshiyasu; Sagawa, Jun*; Shibamoto, Yasuteru; Kukita, Yutaka
Flow Measurement and Instrumentation, 81, p.102006_1 - 102006_9, 2021/10
Times Cited Count：2 Percentile：19.84(Engineering, Mechanical)Wada, Yuki; Satou, Akira; Shibamoto, Yasuteru; Yonomoto, Taisuke; Sagawa, Jun*
Proceedings of 18th International Topical Meeting on Nuclear Reactor Thermal Hydraulics (NURETH-18) (USB Flash Drive), p.4518 - 4531, 2019/08
Liquid film detection under boiling transition (BT) condition is one of the important issues to develop models on dry out and rewet including physical characteristics of liquid film behavior. Although a heater surface temperature has been often used in previous studies to detect the position of liquid film front, it is difficult to accurately identify the position from the temperature measurement. Therefore, we are developing a nonintrusive measurement technique for detecting thin liquid film thickness under BT and rewet condition using ultrasound. In this study, we focus on high accuracy measurement for liquid film thinner than 0.1 mm by using high frequency ultrasound of 15 MHz and developing a signal processing method. Liquid film measurement results were found to agree with liquid film thickness correlations. Based on a comparison with constant current method, it is concluded that the present technique gives more reasonable liquid film thickness than constant current method.
Takeda, Masayasu; Suzuki, Junichi; Yamaguchi, Daisuke; Akiya, Takahiro*; Kato, Hiroaki*; Une, Yasuhiro*; Sagawa, Masato*
Proceedings of 21st International Workshop on Rare-Earth Permanent Magnets and their Applications (REPM 2010), p.161 - 164, 2010/08
We performed small-angle neutron scattering (SANS) measurements of Nd-Fe-B sintered magnets to get information on the averaged internal microstructure of Nd-Fe-B sintered magnets including the interfacial structure which is a key parameter to achieve a high-coercivity Dy-free Nd-Fe-B sintered magnet. SANS patterns from the Nd-Fe-B sintered magnets measured with a two-dimensional detector of a small-angle neutron scattering spectrometer SANS-J-II in the research reactor JRR-3 were sensitive to the sintering and annealing condition of the samples. These results indicate that the SANS measurement is a promising tool to investigate the correlation between the coercivity and the internal microstructure of Nd-Fe-B sintered magnets.
Sagawa, Jun; Shibamoto, Yasuteru
JAEA-Technology 2008-087, 34 Pages, 2009/03
JAEA-Technology-2008-087.pdf:4.03MB
In experimental facilities to investigate a system integral-response and/or to verify fuel rod integrity of nuclear reactors, the electrical heater specially manufactured to simulate the real nuclear fuel rod with the same scale have been used in the core of the experimental facility. This type of the electrical heater, so-called "simulated fuel rod", is a kind of a sheath heater which involves Nichrome coiled wire as a heat generation element in the metal cladding tube. An alternating current power is supplied for heat generation source in this heater and thin thermocouples were embedded on the cladding surface to measure the fuel surface temperature. It means that a switching regulator by silicon-controlled rectifier is used to control the AC electrical power and undesirable electrical noises are superimposed on the thermocouples' signals by the time variation of the heater current. Although a low-pass-filter with a low cut-off frequency was commonly applied to remove the noises in the previous steady-state experiment, the problem have arisen that a fast temperature transient could not be followed due to a time-delay accompanied by the filter in the transient experiment.
Onozawa, Atsushi; Harada, Akio; Honda, Junichi; Nakata, Masahito; Kanazawa, Hiroyuki; Sagawa, Tamio
JAEA-Conf 2008-010, p.325 - 332, 2008/12
The measurement technique for hydrogen concentration using Backscattered Electron Image analysis (BEI method) had been developed by Studsvik Nuclear AB. The hydride in claddings is identified using BEIs with SEM and the hydrogen concentration is calculated from the area fractions of the hydride in those BEIs. In the RFEF, the sample polishing techniques and image processing procedure for BEI method were improved to measure the hydrogen concentration in the irradiated fuel claddings more precisely. In the previous tests using the un-irradiated fuel claddings, it is confirmed improved BEI method has high reliability. The radial and axial hydrogen concentration profiles of the irradiated fuel claddings were measured with improved BEI method. As the results of these measurements, the local hydrogen concentration could be indicated more precisely with the improved BEI method compared to the other methods for the hydrogen concentration measurement and observation.
Sagawa, Jun; Moriyama, Kiyofumi; Nishikizawa, Tomotoshi; Nakamura, Hideo
JAEA-Technology 2008-059, 43 Pages, 2008/09
JAEA-Technology-2008-059.pdf:8.45MB
Electro-chemical electrodes including pH probes, ion-selective electrodes (ISEs) etc. generally have very high output impedances. In order to measure their outputs with generic measurement devices like data recorders, we need impedance conversion amplifiers that convert the ultra-high impedance signals of the probes into low-impedance input signals for ordinary measurement devices. Although specially designed measurement devices for the electro-chemical probes are commercially available, there are very few products that can be applied for multi-channel time series data acquisition. Thus, we designed and fabricated an ultra-high impedance low-offset amplifier fit for this purpose. The primary specification of the amplifier is, input impedance 
10G
, input range 
1V, gain 1
20, response time about 1s, output range 10V, output impedance 50, and it has 5 independent channels. This report describes the originally developed design, selection of the element devices, test on the circuit characteristics, and instruction for fabrication.
Takeishi, Minoru; Miyagawa, Naoto; Uezu, Yasuhiro; Nakano, Masanao; Koarashi, Jun; Mizutani, Tomoko; Kono, Takahiko; Hiyama, Yoshinori*; Fujii, Yoshiyuki*; Kikuchi, Masaaki*; et al.
JAEA-Review 2006-024, 133 Pages, 2006/09
JAEA-Review-2006-024.pdf:6.69MB
Based on the regulations (the safety regulation of Tokai reprocessing plant, the safety regulation of nuclear fuel usage facilities, radiation safety rule, the regulation about prevention from radiation hazards due to radioisotopes, which are related with the nuclear reguratory acts, and the local agreement concerning with security and environment conservation around nuclear facilities, the water pollution control law, and byelaw of Ibaraki prefecture), this report describes the effluent control results of low level liquid waste discharged from the JAEA's Nuclear Fuel Cycle Engineering Laboratories in the fiscal year 2005, from 1st April 2005 to 31th March 2006. In this period, the concentrations and the quantities of the discharged radioactive materials from the reprocessing plant, the plutonium fuel fabrication facilities, and the other facilities were much lower than the authorized limits of the above regulations.
Saito, Junichi; Sagawa, Norihiko; Ohno, Shuji; Hamada, Hirotsugu; Miyahara, Shinya
JNC TN9400 2004-059, 133 Pages, 2004/09
JNC-TN9400-2004-059.pdf:6.05MB
The simplified secondary sodium cooling system, in which utilized lead-bismuth eutectic is utilized as an intermediate coolant has been selected as one of candidate system for the "Feasibility Studies on Commercialized Fast Reactor System (Phase I)". The purpose of this study for the "FS (PhaseII)" is to understand transfer behavior of lead-bismuth in liquid sodium by experiment. The experiments which trickles liquid lead-bismuth into liquid sodium are carried out of under various test temperature and amount of lead-bismuth. The effects of test temperature and amount of lead-bismuth on reaction behavior of sodium and lead-bismuth are clarified from the experimental results. The obtained results from experiments are as follows. (1) The experiment under lower test temperature takes longer time for reaction between sodium and lead-bismuth than that under higher test temperature. It means that test temperature affects the reaction behavior between sodium and lead-bismuth. (2) The amount of dropping lead-bismuth affects an amount and kind of reaction products which are formed by reaction between sodium and lead-bismuth. (3) Reaction heat obtained from the experiments is similar to estimated reaction heat using formation enthalpy of BiNa3 which is one of dominant reaction products.
Saito, Junichi; Takai, Toshihide; Sagawa, Norihiko; Ohno, Shuji; Hamada, Hirotsugu; Miyahara, Shinya
JNC TN9400 2003-057, 87 Pages, 2003/06
JNC-TN9400-2003-057.PDF:24.73MB
The simplified secondary sodium cooling system utilized lead-bismuth eutectic as an intermediate coolant has been selected one of candidate system for the "Feasibility Studies on Commercialized Fast Reactor System (Phase I)". The purpose of this study for the "FS (Phase II)" is to understand transfer behavior of lead-bismuth in liquid sodium by experiment. From the experimental results the fundamental data are obtained for the feasibility evaluation of the simplified secondary sodium cooling system. Twice experiments which trickles liquid lead-bismuth into liquid sodium are carried out at 400 degress centigrade are obtained. (1) From the ICP analyses of L1-1 and L1-2 test, the lead concentration of sodium is higher than the bismuth concentration. This shows that the amount of dissolution of lead into liquid sodium was larger than that of bismuth. This result agrees with data of the previous solubility data in Pb-Na and Bi-Na binary system in sodium. The solid black particles observed in sodium contain a large amount of bismuth. (2) Temperature of liquid sodium rises when the drops of liquid lead-bismuth are added into liquid sodium. The total heating value calculated using temperature rises observed at several parts in equipment is 137 kJ/mol-LBE on L1-2 test. This heat of reaction is promising for leak detection of lead-bismuth into sodium. (3) Many black solid products are observed in sodium taken from L1-1 and L1-2 test apparatus. The reaction products taken from upper location in a sampling finger are very fine and the size was 5 ~ 10
10
Those from lower location increase in size and the size was 50 ~10010-6m.
Shibamoto, Yasuteru; Sagawa, Jun*; Iguchi, Tadashi; Nakamura, Hideo
JAERI-Tech 2003-056, 29 Pages, 2003/06
JAERI-Tech-2003-056.pdf:3.24MB
no abstracts in English
Shibamoto, Yasuteru; Sagawa, Jun*; Kukita, Yutaka*; Nakamura, Hideo
Konsoryu, 17(2), p.171 - 179, 2003/06
A bifunctional probe was developed for simultaneous, high-speed measurement of local temperature and phase of fluid at the same place. It was designed for application to water/melt multi-phase experiments involving transient boiling of water on the surface of molten metal. An unsheathed thermocouple (TC) of a small wire diameter was used for phase detection, that is distinction of melt/water/vapor phase, as well as for temperature measurement of each phase. The phase was detected by measuring the electric impedance between the TC and the ground. A 100-kHz AC signal was imposed on the TC wire for this purpose. The AC signal was filtered out from the temperature signal before it was amplified. With the first design of low-pass filter (LPF), however, a large noise was induced in the temperature signal every time the TC was grounded electrically by contact with molten metal. This problem was overcome by redesigning the LPF. The final design succeeded in measuring the quick movements of interface and the temperature changes in the individual phases in a water-melt-vapor multiphase flow.
TiO
pebblesTsuchiya, Kunihiko; Nakamichi, Masaru; Nagao, Yoshiharu; Fujita, J.*; Sagawa, Hisashi; Tanaka, Satoru*; Kawamura, Hiroshi
Fusion Engineering and Design, 51-52, p.887 - 892, 2000/11
Times Cited Count：16 Percentile：70.34(Nuclear Science & Technology)no abstracts in English
Kawamura, Hiroshi; Tsuchiya, Kunihiko; Nakamichi, Masaru; Fujita, J.*; Sagawa, Hisashi; Nagao, Yoshiharu; Y.Gohar*; ; Saito, Takashi; ; et al.
Fusion Technology 1998, 2, p.1289 - 1292, 1998/00
no abstracts in English
Akiya, Takahiro*; Kato, Hiroaki*; Takeda, Masayasu; Suzuki, Junichi; Yamaguchi, Daisuke; Koizumi, Satoshi; Sagawa, Masato*; Koyama, Keiichi*; Miyazaki, Terunobu*
no journal, ,
Sintered Nd-Fe-B magnets consist of NdFe
B main phase with about 5
m diameter and Nd-rich grain boundary phase. It is well known that the coercivity of sintered Nd-Fe-B magnets is highly dominated by this Nd-rich phase, which is reported to change from discontinuous to continuous arrangement by a low temperature annealing around 500600
C. We have shown that the coercivity of sintered Nd-Fe-B magnets can be further increased by applying a high magnetic field during the annealing. We found that such a coercivity enhancement phenomenon occurred only when a small amount of Cu is added, and when the annealing temperature is around 500C or 550C. In this paper, we report on the results of interface nanostructure analysis by DSC and Small Angle Neutron Scattering experiments to investigate the reason magnetic field effect occurs only in Cu-containing samples at specific annealing temperatures.
Akiya, Takahiro*; Kato, Hiroaki*; Takeda, Masayasu; Suzuki, Junichi; Yamaguchi, Daisuke; Koizumi, Satoshi; Sagawa, Masato*; Koyama, Keiichi*
no journal, ,
Sintered Nd-Fe-B magnets are the most promising materials for a driving motor of the hybrid electric vehicles(HV). In this application, a large value of coecivity 
is required because of the high operating temperature beyond 450 K. As a symptomatic treatment, Nd has been replaced partly by Dy to enhance . But the problem is an estimated short supply of Dy in the HV mass-production stage due to its low natural abundance. We have recently shown that of Nd-Fe-B magnets can be enhanced by applying a high magnetic field during the annealing. In order to elucidate the reason for the increase, we performed a small angle neutron scattering (SANS) study using SANS-J and PNO at JRR-3 of JAEA. We observed a marked deviation from the simple relation above for 
in the sample with Al and Cu additives. SANS results suggest that an existence of the Cu-containing liquid phases is strongly correlated with the enhancement by the high field annealing.
Takeda, Masayasu; Suzuki, Junichi; Yamaguchi, Daisuke; Koizumi, Satoshi; Akiya, Takahiro*; Kato, Hiroaki*; Sagawa, Masato*
no journal, ,
no abstracts in English
Akiya, Takahiro*; Kato, Hiroaki*; Takeda, Masayasu; Suzuki, Junichi; Yamaguchi, Daisuke; Koizumi, Satoshi; Sagawa, Masato*; Koyama, Keiichi*
no journal, ,
no abstracts in English
B sintered magnetsTakeda, Masayasu; Suzuki, Junichi; Yamaguchi, Daisuke; Akiya, Takahiro*; Kato, Hiroaki*; Sagawa, Masato*; Koyama, Keiichi*
no journal, ,
Nd-Fe-B magnets are now widely used because of the highest BH
of them in the commercially available magnets. At the present, Dy, which is one of the rare metals, has to be added to maintain the coercivity especially in the operational temperatures higher than the room temperature. The key to achieve the Dy-free Nd-Fe-B magnets is how to control the grain size and the structure near the grain boundary. We have performed the small-angle neutron scattering (SANS) measurements of the sintered Nd-Fe-B magnets using unpolarized and polarized neutrons to obtain the averaged internal structures of samples with the different coercivity introduced by applying different high magnetic fields during the annealing. We found that inhomogeneity was induced by the magnetic fields applied parallel to 
. The relation between the inhomogeneity and the coercivity force is unclear at the moment, but we will present possible interpretation.
Takeda, Masayasu; Suzuki, Junichi; Yamaguchi, Daisuke; Akiya, Takahiro*; Kato, Hiroaki*; Une, Yasuhiro*; Sagawa, Masato*
no journal, ,
We have been investing the correlation between the coercive force and the averaged internal structure of Neodymium-Iron-Boron (Nd-Fe-B) sintered magnets using the small-angle neutron scattering (SANS) spectrometer, SANS-J-II installed at the beam hall of the research reactor JRR-3 in Tokai. The correlation is a clue to achieve the less or Dysprosium (Dy)-free Nd-Fe-B sintered magnets with high coercivity for high-temperature application. In this talk, we report that the coercivity is very sensitive to the averaged diameter of powder and the temperature in sintering process, and that the SANS patterns on 2-dimensional position-sensitive detector (2D-PSD) are also sensitively changed following the sintering condition.
