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-wave direct capture and interference effect observed in the 
O
O reactionNagai, Yasuki*; Kinoshita, Mitsutaka*; Igashira, Masayuki*; Nobuhara, Yuriko*; Makii, Hiroyuki; Mishima, Kenji*; Shima, Tatsushi*; Mengoni, A.*
Physical Review C, 102(4), p.044616_1 - 044616_8, 2020/10
Times Cited Count：2 Percentile：32.51(Physics, Nuclear)Mishima, Ria; Inaba, Yusuke*; Tachioka, Sotaro*; Harigai, Miki*; Watanabe, Shinta*; Onoe, Jun*; Nakase, Masahiko*; Matsumura, Tatsuro; Takeshita, Kenji*
Chemistry Letters, 49(1), p.83 - 86, 2020/01
Times Cited Count：2 Percentile：13.92(Chemistry, Multidisciplinary)Separation of platinum group metals (PGMs) from high-level liquid waste generated from the reprocessing of spent nuclear fuels is important to produce good quality vitrified glass for final disposal. A new sorbent, Aluminum hexacyanoferrate (AlHCF), was synthesized and the general sorption behavior of PGMs from concentrated nitric acid was examined. Nitric acid caused substantial elution of AlHCF but the sorption of Pd stabilized the structure. Consequently, Rh was sorbed in the presence of Pd, whereas single Rh sorption caused complete dissolution of AlHCF. Relation between sorbed mount of Pd vs eluted Al and Fe revealed that the elution ratio of Al and Fe was not the same as molar ratio of synthesized AlHCF, indicating the re-sorption of Fe resulted in formation of new structure. The sorption mechanism of PGMs by this new sorbent, AlHCF, not only the simple ion exchange, but also oxidation reduction reaction as well as kinetics play important rule. Understanding the general sorption and dissolution behavior will help improve the sorption performance of PGMs by AlHCF.
Teshigawara, Makoto; Tsuchikawa, Yusuke*; Ichikawa, Go*; Takata, Shinichi; Mishima, Kenji*; Harada, Masahide; Oi, Motoki; Kawamura, Yukihiko*; Kai, Tetsuya; Kawamura, Seiko; et al.
Nuclear Instruments and Methods in Physics Research A, 929, p.113 - 120, 2019/06
Times Cited Count：14 Percentile：87.68(Instruments & Instrumentation)A nano-diamond is an attractive neutron reflection material below cold neutron energy. The total neutron cross section of a nano-diamond was derived from a neutron transmission measurement over the neutron energy range of 0.2 meV to 100 meV because total neutron cross section data were not available. The total cross section of a nano-diamond with particle size of approximately 5 nm increased with a decrease in neutron energy to 0.2 meV. It was approximately two orders of magnitude larger than that of graphite at 0.2 meV. The contribution of inelastic scattering to the total cross section was to be shown negligible small at neutron energies of 1.2, 1.5, 1.9, 2.6, and 5.9 meV in the inelastic neutron scattering measurement. Moreover, small-angle neutron scattering measurements of the nano-diamond showed a large scattering cross section in the forward direction for low neutron energies.
Nakajima, Kenji; Kawakita, Yukinobu; Ito, Shinichi*; Abe, Jun*; Aizawa, Kazuya; Aoki, Hiroyuki; Endo, Hitoshi*; Fujita, Masaki*; Funakoshi, Kenichi*; Gong, W.*; et al.
Quantum Beam Science (Internet), 1(3), p.9_1 - 9_59, 2017/12
The neutron instruments suite, installed at the spallation neutron source of the Materials and Life Science Experimental Facility (MLF) at the Japan Proton Accelerator Research Complex (J-PARC), is reviewed. MLF has 23 neutron beam ports and 21 instruments are in operation for user programs or are under commissioning. A unique and challenging instrumental suite in MLF has been realized via combination of a high-performance neutron source, optimized for neutron scattering, and unique instruments using cutting-edge technologies. All instruments are/will serve in world-leading investigations in a broad range of fields, from fundamental physics to industrial applications. In this review, overviews, characteristic features, and typical applications of the individual instruments are mentioned.
and 
cross sections of the 
C(
,
)O reaction at 
1.2 MeV using pulsed beamsMakii, Hiroyuki; Ueda, Hitoshi*; Temma, Yasuyuki*; Nagai, Yasuki*; Shima, Tatsushi*; Fujimoto, Shinya*; Segawa, Mariko; Mishima, Kenji*; Nishiyama, Jun*; Igashira, Masayuki*
AIP Conference Proceedings 1269, p.283 - 288, 2010/10
Times Cited Count：0 Percentile：0.02The C(,)O reaction cross section plays an important role in stellar evolution at the stage of helium-burning. However, the cross section at low energy still has a large uncertainty mainly due to the poor determination of the ratio of cross section to one. Hence, we have installed new system to make a precise measurement of the cross section. In this experiment, we used the high efficiency anti-Compton NaI(Tl) spectrometers with a large S/N ratio, an intense pulsed beams, and the monitoring system of target thickness. With use of the system we succeeded in removing a background due to neutron and could clearly detect the -ray from the C(,)O reaction with high statistics. We determined the and cross section down to 
1.2 MeV, and thus obtained results are compared to recent theoretical calculations.
and cross sections of the C
O reaction using pulsed beamsMakii, Hiroyuki; Nagai, Yasuki*; Shima, Tatsushi*; Segawa, Mariko; Mishima, Kenji*; Ueda, Hitoshi*; Igashira, Masayuki*; Osaki, Toshiro*
Physical Review C, 80(6), p.065802_1 - 065802_16, 2009/10
Times Cited Count：30 Percentile：84.07(Physics, Nuclear)We measured the -ray angular distribution from CO to the ground state of O using a pulsed beam at 
and 1.4 MeV. True events of CO were discriminated from background events due to neutrons from 
C(
)O with a time-of-flight method. The obtained -ray spectrum with anti-Compton NaI(Tl) spectrometers showed a characteristic line shape from CO: the Doppler broadening and energy loss of particles in C targets. The astrophysical S factors for and , 
and 
, derived from the present cross sections are in excellent agreement with the values derived by 
-matrix calculation of the 
-delayed spectrum of N, and by using the asymptotic normalization constant in the -matrix fit.
Mishima, Kenji*; Ino, Takashi*; Sakai, Kenji; Shinohara, Takenao; Hirota, Katsuya*; Ikeda, Kazuaki*; Sato, Hiromi*; Otake, Yoshie*; Omori, Hitoshi*; Muto, Suguru*; et al.
Nuclear Instruments and Methods in Physics Research A, 600, p.342 - 345, 2009/02
Times Cited Count：27 Percentile：85.31(Instruments & Instrumentation)A new beamline for a fundamental physics experiment is under construction at BL05 port in the Materials and Life Science Facility (MLF) at Japan Proton Accelerator Research Complex (J-PARC), this beamline is designed using novel techniques of neutron optics and it is termed "Neutron Optics and Physics". The beam from the moderator is deflected by multi-channel supermirrors and split into three branches for individual experiments. In this study, we have optimized the design of the beam optics and shields using the Monte Carlo simulation package PHITS. The neutron fluxes of beams are expected to be 
cm
str
sMW, 
cm
sMW, 
cmsMW, with polarization of 99.8%.
Kondo, Masaaki; Kimishima, Satoru*; Emori, Koichi; Sekita, Kenji; Furusawa, Takayuki; Hayakawa, Masato; Kozawa, Takayuki; Aono, Tetsuya; Kuroha, Misao; Ouchi, Hiroshi
JAEA-Technology 2008-062, 46 Pages, 2008/10
JAEA-Technology-2008-062.pdf:11.62MB
The reactor containment of HTTR is tested to confirm leak-tight integrity of itself. "Type A test" has been conducted in accordance with the standard testing method in JEAC4203 since the preoperational verification of the containment was made. Type A tests are identified as basic one for measuring containment leakage rate, it costs much, however. Therefore, the test program for HTTR was revised to adopt an efficient and economical alternatives including "Type B and Type C tests". In JEAC4203-2004, following requirements are specified for adopting alternatives: upward trend of leakage rate by Type A test due to aging should not be recognized; criterion of combined leakage rate with Type B and Type C tests should be established; the criteria for Type A test and combined leakage rate test should be satisfied; correlation between the leakage rates by Type A test and combined leakage rate test should be recognized. Considering the performances of the tests, the policies of corresponding to the requirements were developed, which were accepted by the regulatory agency. This report presents an outline of the tests, identifies issues on the conventional test and summarizes the policies of corresponding to the requirements and of implementing the tests based on the revised program.
and cross sections of the C(
O reaction at 
1.4 MeV using pulsed beamsMakii, Hiroyuki; Nagai, Yasuki; Mishima, Kenji*; Segawa, Mariko; Shima, Tatsushi*; Ueda, Hitoshi; Igashira, Masayuki*
AIP Conference Proceedings 1016, p.215 - 220, 2008/05
The C(O reaction plays an important role in stellar evolution at the stage of helium-burning. However, the cross section at low energy still has a large uncertainty mainly due to the poor determination of the 
ratio. We have installed a new system to measure the -ray angular distribution of the C(O reaction to accurately determine the 
and 
. In this experiment, we used high efficiency anti-Compton NaI(Tl) spectrometers to detect a -ray from the reaction with a large S/N ratio, intense pulsed beams to discriminate true events from neutron induced background with a time-of-flight method, and the monitoring system of target thickness. We succeeded in removing a background due to neutrons and could clearly detect the -ray from the C(O reaction with high statics.
Os, 
Os, and 
Os and the Re-Os chronologySegawa, Mariko; Nagai, Yasuki*; Masaki, Tomohiro*; Temma, Yasuyuki*; Shima, Tatsushi*; Mishima, Kenji*; Igashira, Masayuki*; Goriely, S.*; Koning, A.*; Hilaire, S.*
AIP Conference Proceedings 1016, p.448 - 450, 2008/05
Re-Os pair is known as the most promising nuclear cosmochronometer with considerable potential. However, there remains non-trivial problems related to an excited neutron capture reaction of Os at a stellar temperature. Firstly, Os is produced and depleted by the slow process nucleosynthesis. Hence, it is necessary to obtain both the production and depletion rates of Os. Secondly, Os is depleted not only by its ground state neutron capture reaction but also by an excited state neutron capture reaction of Os in a stellar temperature. In the present study, we have measured the neutron capture reaction cross sections for Os, Os and Os accurately and neutron inelastic scattering reaction cross section for Os off the ground state of Os to its 9.75 keV first excited state in the neutron energy range from 10 to 100 keV.
-ray detector in a C(
)O reaction studyMakii, Hiroyuki; Nagai, Yasuki*; Mishima, Kenji*; Segawa, Mariko; Shima, Tatsushi*; Igashira, Masayuki*
Physical Review C, 76(2), p.022801_1 - 022801_5, 2007/08
Times Cited Count：14 Percentile：68.36(Physics, Nuclear)Neutron-induced background events occurring within a -ray detector in the C(,)O reaction study are discussed by comparing a spectrum taken by a NaI(Tl) detector with a pulsed -beam with that taken previously by a Ge detector using a continuous -beam. Both spectra contain such background events induced by neutrons from the 
reaction on C and/or 
Be contained in enriched C targets. These observations together with a calculated -ray spectrum of the neutron-induced reaction by Ge isotopes indicate the thus-produced background events, which would be hardly reduced by using shield materials, become significant background in the C(,)O reaction study at low -beam energy.
Os, Os, and Os for the Re-Os chronologySegawa, Mariko; Masaki, Tomohiro*; Nagai, Yasuki*; Temma, Yasuyuki*; Shima, Tatsushi*; Mishima, Kenji*; Igashira, Masayuki*; Goriely, S.*; Koning, A.*; Hilaire, S.*
Physical Review C, 76(2), p.022802_1 - 022802_5, 2007/08
Times Cited Count：17 Percentile：73.26(Physics, Nuclear)Discrete as well as continuum -ray energy spectra from the neutron capture by Os, Os, and Os have been taken for the first time at 5 
En 90 keV by an anti-Compton NaI(Tl) spectrometer. The detection of a weak discrete -ray, about 0.5% of total -ray strength, demonstrates the high sensitivity of the present measurement. The energy spectra enabled us to accurately determine the reaction cross sections with a small systematic uncertainty. Based on the new cross sections, we re-estimate on the basis of a careful reaction cross section calculation the correction factor F
for the neutron capture on the 9.75-keV first excited state in Os as a function of stellar temperature, as required to derive the age of the Galaxy within the Re-Os chronology.
Oku, Takayuki; Yamada, Satoru; Shinohara, Takenao; Suzuki, Junichi; Mishima, Kenji*; Hirota, Katsuya*; Sato, Hiromi*; Shimizu, Hirohiko
Physica B; Condensed Matter, 397(1-2), p.188 - 191, 2007/07
Times Cited Count：5 Percentile：27.67(Physics, Condensed Matter)We have studied a neutron polarization method by means of a quadrupole magnet. By passing through the aperture of the quadrupole magnet (QM), positive and negative polarity neutrons are accelerated in opposite directions and spatially separated due to the magnetic field gradient. Then, by extracting one spin component, we can obtain a highly polarized neutron beam. Since polarized neutrons do not interact with any substances in this method, we can obtain the polarized neutron beam free from neutron attenuation. As a result of a cold neutron beam polarization experiment by using the QM, we obtained extremely high neutron polarization degree P0.999. In this paper, we show some experimental results of the neutron polarization experiment and discuss the application of the QM-based polarizing device to neutron scattering experiments.
Kondo, Masaaki; Sekita, Kenji; Emori, Koichi; Sakaba, Nariaki; Kimishima, Satoru; Kuroha, Misao; Noji, Kiyoshi; Aono, Tetsuya; Hayakawa, Masato
JAEA-Testing 2006-002, 55 Pages, 2006/07
JAEA-Testing-2006-002.pdf:6.36MB
The leakage rate test for the reactor containment vessel of HTTR is conducted in accordance with the absolute pressure method provided in Japan Electric Association Code(JEAC4203). Although leakage test of a reactor containment vessel is, in general, performed in condition of reactor coolant pressure boundary to be opened in order to simulate an accident, the peculiar test method to HTTR which use the helium gas as reactor coolant has been established, in which the pressure boundary is closed to avoid the release of fission products into the environment of the reactor containment vessel. The system for measuring and calculating the data for evaluating the leakage rate for containment vessel of HTTR was developed followed by any modifications. Recently, the system has been improved for more accurate and reliable one with any useful functions including real time monitoring any conditions related to the test. In addition, the configuration of containment vessel boundary for the test and the calibration method for the detectors for measuring temperature in containment vessel have been modified by reflecting the revision of the Code mentioned above. This report describes the method, system configuration, and procedures for the leakage rate test for reactor containment vessel of HTTR.
Sekita, Kenji; Emori, Koichi; Kuroha, Misao; Kimishima, Satoru; Wakabayashi, Hiroshi
JAEA-Testing 2006-001, 49 Pages, 2006/06
JAEA-Testing-2006-001.pdf:6.24MB
no abstracts in English
Hamamoto, Shimpei; Iigaki, Kazuhiko; Shimizu, Atsushi; Sawahata, Hiroaki; Kondo, Makoto; Oyama, Sunao; Kawano, Shuichi; Kobayashi, Shoichi; Kawamoto, Taiki; Suzuki, Hisashi; et al.
JAEA-Technology 2006-030, 58 Pages, 2006/03
JAEA-Technology-2006-030.pdf:10.69MB
During normal operation of High Temperature engineering Test Reactor (HTTR) in Japan Atomic Energy Agency (JAEA), the reactivity is controlled by the Control Rods (CRs) system which consists of 32 CRs (16 pairs) and 16 Control Rod Drive Mechanisms (CRDMs). The CR system is located in stand-pipes accompanied by the Reserved Shutdown System (RSS). In the unlikely event that the CRs fail to be inserted, the RSS is provided to insert B
C/C pellets into the core. The RSS shall be designed so that the reactor should be held subcriticality from any operation condition by dropping in the pellets. The RSS consists of BC/C pellets, hoppers which contain the pellets, electric plug, driving mechanisms, guide tubes and so on. In accidents when the CRs cannot be inserted, an electric plug is pulled out by a motor and the absorber pellets fall into the core by gravity. A trouble, malfunction of one RSS out of sixteen, occurred during a series of the pre-start up checks of HTTR on February 21, 2005. We investigated the cause of the RSS trouble and took countermeasures to prevent the issue. As the result of investigation, the cause of the trouble was attributed to the following reason: In the motor inside, The Oil of grease of the multiplying gear flowed down from a gap of the oil seal which has been deformed and was mixed with abrasion powder of brake disk. Therefore the adhesive mixture prevented a motor from rotating.
Kitamura, Seiji; Okamura, Shigeki; Takahashi, Kenji; Kamishima, Yoshio*; Somaki, Takahiro*; Morishita, Masaki
Proceedings of 9th World Seminar on Seismic Isolation, Energy Dissipation and Active Vibration Control of Structures (CD-ROM), p.209 - 216, 2005/00
A structural concept of a vertical component isolation system for fast reactors, assuming a building adopting a horizontal base isolation system, has been studied. In this concept, a reactor vessel and major primary components are suspended from a large common deck supported by vertical isolation devices consisting of large coned disk springs. We designed the isolation device, which could be achieved vertical isolation frequency of 1 Hz and damping ratio of 20 %. Full scale coned disk spring and damper performance tests were carried out to verify the validity of design equations. And a series of shaking table test using a 1/8 scale model was performed. The test results fit well the simulation analysis results, so the validity of the design methods was able to be verified. The prospect that the vertical component isolation system applied to the FBR plant could technically realize was obtained.
Mishima, Kenji*; Tani, Norio
Dai-14-Kai Kasokuki Kagaku Kenkyu Happyokai Hokokushu, 3 Pages, 2003/11
no abstracts in English
Kawai, Masayoshi*; Furusaka, Michihiro*; Kikuchi, Kenji; Kurishita, Hiroaki*; Watanabe, Ryuzo*; Li, J.*; Sugimoto, Katsuhisa*; Yamamura, Tsutomu*; Hiraoka, Yutaka*; Abe, Katsunori*; et al.
Journal of Nuclear Materials, 318, p.35 - 55, 2003/05
R&D works for MW class solid target composed of tungsten to produce pulsed intense neutron source has been made in order to construct a future scattering facility. Three methods were investigated to prevent corrosion of tungsten from water; those are hipping, brazing and electric coating in molten salt bath. Hipping condition was optimized to be 1500 degree C in the previous work: here small punch test shows highest load for crack initiation of hipped materials at the boundary of W/Ta. The basic techniques for the other two methods were developed. Erosion test showed that uncovered W is susceptible of flowing water velocity. At high velocity w is easy to be eroded. For solid target design slab type and rod type targets were studied. As long as the optimized neutron performance is concerned, 1MW solid target is better than mercury target.
Mishima, Kaichiro*; Hibiki, Takashi*; Fujine, Shigenori*; Yoneda, Kenji*; Kanda, Keiji*; Nishihara, Hideaki*; Matsubayashi, Masahito; Tsuruno, Akira
Fifth World Conf. on Neutron Radiography, 0, p.140 - 147, 1996/00
no abstracts in English
