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Journal Articles

Establishment of reasonable 2-D model to investigate heat transfer and flow characteristics by using scale model of vessel cooling system for HTTR

Takada, Shoji; Ngarayana, I. W.*; Nakatsuru, Yukihiro*; Terada, Atsuhiko; Murakami, Kenta*; Sawa, Kazuhiro*

Mechanical Engineering Journal (Internet), 7(3), p.19-00536_1 - 19-00536_12, 2020/06

https://doi.org/10.1299/mej.19-00536

In this study reasonable 2D model was established by using FLUENT for start-up of analysis and evaluation of heat transfer flow characteristics in 1/6 scale model of VCS for HTTR. By setting up pressure vessel temperature around 200$$^{circ}$$C about relatively high ratio of heat transfer via natural convection in total heat removal around 20-30%, which is useful for code to experiment benchmark in the aspect to confirm accuracy to predict temperature distribution of components which is heated up by natural convection flow. The numerical results of upper head of pressure vessel by the $$kappa$$-$$omega$$-SST intermittency transition model, which can adequately reproduce the separation, re-adhesion and transition, reproduced the test results including temperature distribution well in contrast to those by the $$kappa$$-$$varepsilon$$ model in both cases that helium gas is evacuated or filled in the pressure vessel. It was emerged that any local hot spot did not appear on the top of upper head of pressure vessel where natural convection flow of air is separated in both cases. In addition, the plume of high temperature helium gas generated by the heating of heater was well mixed in the upper head and uniformly heated the inner surface of upper head without generating hot spots.

Journal Articles

Establishment of numerical model to investigate heat transfer and flow characteristics by using scale model of vessel cooling system for HTTR

Takada, Shoji; Ngarayana, I. W.*; Nakatsuru, Yukihiro*; Terada, Atsuhiko; Murakami, Kenta*; Sawa, Kazuhiko*

Proceedings of 27th International Conference on Nuclear Engineering (ICONE-27) (Internet), 13 Pages, 2019/05

In the loss of core cooling test using HTTR, a technical issue is to improve prediction accuracy of temperature distribution of components in vessel cooling system (VCS). An establishment of reasonable 2D model was started by using numerical code FLUENT, which was validated using the test data by 1/6 scale model of VCS for HTTR. The pressure vessel (PV) temperature was set around 200$$^{circ}$$C attributed to relatively high ratio of natural convection heat transfer around 20% in total heat removal, which is useful for code to experiment benchmark to improve prediction accuracy. It is necessary to confirm heat transfer flow characteristics around the top of PV which is heated up by natural convection flow which was considered to be affected by separation, re-adhesion and transition flow. The k-$$omega$$-SST model was selected for turbulent calculation attributed to predict the effects mentioned above adequately. The numerical results using the k-$$omega$$-SST model reproduced the temperature distribution of PV especially the top region which is considered to be affected by separation, re-adhesion and transition flow in contract to that using k-$$varepsilon$$ model which does not account the effects.

Journal Articles

Characterization of Multiple Prompt Gamma-ray Analysis (MPGA) system at JAEA for elemental analysis of geological and cosmochemical samples

Islam, M. A.*; Ebihara, Mitsuru*; Toh, Yosuke; Murakami, Yukihiro*; Harada, Hideo

Applied Radiation and Isotopes, 70(8), p.1531 - 1535, 2012/08

https://doi.org/10.1016/j.apradiso.2012.04.003
 Times Cited Count：1 Percentile：8.93(Chemistry, Inorganic & Nuclear)

In this study, the MPGA system was characterized for nondestructive multi-element analysis of geological and cosmochemical samples. Among the three offline sorting modes of coincidence data in MPGA, the add-back mode resulted in relatively high analytical sensitivity and the lowest detection limit. The system is highly sensitive to Sm, Gd and Cd. When MPGA detection limits of the studied elements were compared with other cold neutron facilities, MPGA detection limits for Mg, K, S and Cl were improved around one order of magnitude than other facilities under the present experimental conditions, which consists of 8 Clover and BGO detectors. Analysis of the meteorite Orgueil by both MPGA and PGA imply that MPGA can be used for elemental analysis with sufficient accuracy. For some elements (such as Sm, K and Mg) which can Gnot be determined by conventional PGA, due to the spectral interference or lower sensitivity, it was observed that they could be determined accurately (3%) by MPGA.

Journal Articles

Spectroscopic study of $$^{63}$$Ni via cold neutron capture reaction, 1; Nuclear structure of $$^{63}$$Ni

Oshima, Masumi; Kin, Tadahiro*; Nakamura, Shoji; Homma, Michio*; Minato, Futoshi; Hayakawa, Takehito; Hara, Kaoru; Kimura, Atsushi; Koizumi, Mitsuo; Harada, Hideo; et al.

Journal of the Physical Society of Japan, 81(8), p.084201_1 - 084201_15, 2012/08

https://doi.org/10.1143/JPSJ.81.084201
 Times Cited Count：2 Percentile：17.96(Physics, Multidisciplinary)

The $$gamma$$-radiation has been investigated produced by cold neutron capture in an enriched $$^{62}$$Ni sample. The 315 $$gamma$$-rays have been placed in the $$^{63}$$Ni level scheme of which 272 placements are new. We have determined excitation energies with 0.2-0.8 keV error and branching ratios of 62 bound levels in $$^{63}$$Ni, including 30 new levels. The Q-value of the $$^{62}$$Ni (n,$$gamma$$) $$^{63}$$Ni reaction amounts to 6837.75 (18) keV. A large-scale shell-model calculation has been performed and the energies of the low-lying $$^{63}$$Ni states are successfully reproduced. A mean-field statistical model calculation has been also made by using a self-consistent interaction between the Hartree-Fock + BCS method and the statistical calculation. The calculation result is consistent with the experimental level density of $$^{63}$$Ni.

Journal Articles

Feasibility study for the quantification of total protein content by multiple prompt $$gamma$$-ray analysis

Toh, Yosuke; Murakami, Yukihiro*; Furutaka, Kazuyoshi; Kimura, Atsushi; Koizumi, Mitsuo; Hara, Kaoru; Kin, Tadahiro; Nakamura, Shoji; Harada, Hideo

Applied Radiation and Isotopes, 70(6), p.984 - 987, 2012/06

https://doi.org/10.1016/j.apradiso.2012.02.116
 Times Cited Count：4 Percentile：28.65(Chemistry, Inorganic & Nuclear)

By applying the multiple $$gamma$$-ray detection method to prompt $$gamma$$-ray analysis, called MPGA (multiple prompt $$gamma$$-ray analysis), the interference from hydrogen contained in a sample can be reduced. Therefore, this method can improve the signal-to-noise ratio, and provide a rapid screening method of toxic elements. We developed a neutron beam line and a detector system for MPGA, which consists of eight Clover Ge detectors, was constructed at the cold neutron guide C2-3-2 of JRR-3. Protein is an important nutrient in foods. The classical total protein analysis method is the Kjeldahl technique, which is time-consuming and inconvenient. As a convenient method to quantify total protein content in biological samples, the feasibility of application of MPGA to the quantification was studied. The results obtained with reference materials are in good agreement with the certified value. MPGA provides a tool for the rapid and non-destructive quantification of total protein content.

Journal Articles

Chemical composition of sediments from marine shallow-water hydrothermal mounds in Wakamiko submarine crater revealed by multiple prompt $$gamma$$-ray analysis

Shozugawa, Katsumi*; Matsuo, Motoyuki*; Sano, Yuji*; Toh, Yosuke; Murakami, Yukihiro*; Furutaka, Kazuyoshi; Koizumi, Mitsuo; Kimura, Atsushi; Hara, Kaoru; Kin, Tadahiro; et al.

Journal of Radioanalytical and Nuclear Chemistry, 291(2), p.341 - 346, 2012/02

https://doi.org/10.1007/s10967-011-1347-9
 Times Cited Count：3 Percentile：22.50(Chemistry, Analytical)

Multiple prompt $$gamma$$-ray analysis (MPGA), a new quantification method with high energy resolution, was applied to sediments from a marine shallow-water hydrothermal mound. Surface sediments around mounds were collected from the Wakamiko submarine crater located in Kagoshima Bay, southwest Japan, where the hydrothermal system was different from those at other marine shallow-water hydrothermal mounds. All samples were desalted and MPGA measurements were performed for 4,500 s (real time). Event data were obtained using eight CLOVER Ge detectors. We could obtain concentrations of $$^{32}$$S, $$^{55}$$Mn, $$^{75}$$As, $$^{157}$$Gd, $$^{39}$$K, $$^{149}$$Sm, $$^{56}$$Fe, and $$^{85}$$Rb with high sensitivity by MPGA. Furthermore, $$^{32}$$S, $$^{85}$$Rb, and $$^{55}$$Mn have characteristic concentrations only at a mound, suggesting that sediments were sulfated by magmatic fluids at this mound.

Journal Articles

Application of multiple prompt $$gamma$$-ray analysis (MPGA) to geochemical and cosmochemical samples

Oura, Yasuji*; Watanabe, Ryo*; Ebihara, Mitsuru*; Murakami, Yukihiro*; Toh, Yosuke; Kimura, Atsushi; Koizumi, Mitsuo; Furutaka, Kazuyoshi; Oshima, Masumi; Hara, Kaoru; et al.

Journal of Radioanalytical and Nuclear Chemistry, 291(2), p.335 - 339, 2012/02

https://doi.org/10.1007/s10967-011-1292-7
 Times Cited Count：4 Percentile：28.65(Chemistry, Analytical)

We applied multiple prompt $$gamma$$-ray analysis (MPGA) method to geochemical and cosmochemical samples to evaluate its analytical performance on signal to noise (S/N) ratio, sensitivity, and detection limit. The S/N ratio measured by MPGA system was larger than that by normal prompt $$gamma$$ ray activation analysis (PGAA) at JRR3. For some elements, the S/N ratio was improved more than ten times. Several elements that are not detected by PGAA were detected by MPGA. In the present experiment, concentrations of major elements and trace elements with high neutron capture cross section in geochemical and cosmochemical samples were determined accurately by the MPGA system. It is expected that it will determine a lot of trace elements after appropriate adjustments and modifications.

Journal Articles

Development of a trace element quantification method based on neutron activation analysis coupled with multiple $$gamma$$-ray detection

Oshima, Masumi; Toh, Yosuke; Murakami, Yukihiro*

Bunseki, 2009(7), p.362 - 368, 2009/07

https://ci.nii.ac.jp/naid/10025216809

We have developed the multiple $$gamma$$-ray detection method which provide a tool for high-resolution and high-sensitivity elemental quantification. By applying this method to neutron activation analysis (NAA) and prompt $$gamma$$-ray analysis (PGA) we have succeeded in the improvement of these analysis methods. We will review the principle of the multiple $$gamma$$-ray detection method, experimental apparatuses for NAA and MPGA and expected performances in those analyses.

Journal Articles

Cu K$$alpha$$ pulse generation in an X-ray tube with a plasma cathode induced by a femtosecond laser pulse

Yamada, Hidetaka; Murakami, Hiroshi; Shimada, Yukihiro

Radiation Physics and Chemistry, 78(6), p.375 - 379, 2009/06

https://doi.org/10.1016/j.radphyschem.2009.03.069
 Times Cited Count：1 Percentile：9.62(Chemistry, Physical)

no abstracts in English

Journal Articles

An Automatic liquid-nitrogen filling system for multiple Ge detectors

Koizumi, Mitsuo; Oshima, Masumi; Toh, Yosuke; Kimura, Atsushi; Kin, Tadahiro; Furutaka, Kazuyoshi; Murakami, Yukihiro*; Osa, Akihiko; Ando, Shingo*

Review of Scientific Instruments, 80(1), p.016102_1 - 016102_3, 2009/01

https://doi.org/10.1063/1.3059684
 Times Cited Count：2 Percentile：11.83(Instruments & Instrumentation)

In order to reduce time and effort of the daily task of refilling Dewar vessels of Ge detectors with LN$$_2$$, we have developed an automatic LN$$_2$$ filling system equipped with an LN$$_2$$ plant. With the system, our multiple Ge detector system became almost maintenance free. Such an LN$$_2$$ filling system is useful for moderate-scale Ge detector arrays consisting of less than 20 Ge detectors.

Journal Articles

Development of time-resolved X-ray fluorescence spectroscopy system using an X-ray tube driven by ultrafast pulsed laser

Yamada, Hidetaka; Murakami, Hiroshi; Shimada, Yukihiro

Hyomen Kagaku, 29(7), p.413 - 417, 2008/07

https://doi.org/10.1380/jsssj.29.413

A femtosecond-laser-driven X-ray source and an X-ray focusing system have been developed for the time-resolved X-ray fluorescence spectroscopy. The X-ray source, in which a plasma cathode induced by a 10$$^{13}$$-W/cm$$^2$$ laser pulse serves as an electron source of an X-ray tube, provides 10$$^9$$ Cu K$$_alpha$$ photons in 4$$pi$$sr per pulse. The X-ray pulse duration is measured to be about two hundred nanoseconds. Emission analysis of the plasma cathode indicates that the temporal characteristics of the X-ray pulse are determined by the dynamics of the plasma particles under the electrostatic shielding against the applied voltage in the X-ray tube. As for the X-ray focusing system, a focal spot size by a polycapillary lens is measured and the enhancement of X-ray fluorescence intensity due to the lens is demonstrated.

Journal Articles

Application of $$gamma$$-$$gamma$$ coincidence method to instrumental neutron activation analysis and prompt $$gamma$$-ray analysis

Oshima, Masumi; Toh, Yosuke; Koizumi, Mitsuo; Furutaka, Kazuyoshi; Kin, Tadahiro; Kimura, Atsushi; Murakami, Yukihiro*; Goto, Jun*

Proceedings of 9th International Conference on Applications of Nuclear Techniques (CD-ROM), 8 Pages, 2008/06

The $$gamma$$-$$gamma$$ coincidence techniques developed for nuclear structure study has proved to be useful for nuclear quantification. The applications to Neutron Activation Analysis and Prompt $$gamma$$-ray Analysis are presented.

Journal Articles

Transient-Grating FROG for measurement of sub-10-fs to few-ps amplified pulses

Pirozhkov, A. S.; Mori, Michiaki; Ogura, Koichi; Nishimura, Akihiko; Murakami, Hiroshi; Shimada, Yukihiro; Sagisaka, Akito; Orimo, Satoshi; Kimura, Toyoaki; Daido, Hiroyuki

Advanced Solid-State Photonics; OSA Technical Digest Series (CD-ROM), p.MC8_1 - MC8_3, 2008/01

https://doi.org/10.1364/ASSP.2008.MC8

Oral presentation

Application of triple $$gamma$$ coincidence in prompt $$gamma$$-ray analysis and neutron activation analysis

Oshima, Masumi; Toh, Yosuke; Murakami, Yukihiro*; Hatsukawa, Yuichi; Kin, Tadahiro; Kimura, Atsushi; Nakamura, Shoji; Koizumi, Mitsuo; Furutaka, Kazuyoshi

no journal, , 

Prompt $$gamma$$-ray analysis (PGA) is a versatile element quantification method with non-destructive, rapid, high-precision and multi-element determination. In actual application, however, the energy resolution of commercial Ge detectors is not sufficient and it is impossible to resolve all the $$gamma$$-rays, since the number of $$gamma$$-rays from the sample with multiple elements often exceeds one thousand. In a similar situation in Neutron Activation Analysis (NAA), we have applied a $$gamma$$-ray coincidence method (multiple $$gamma$$-ray detection method), and developed a new method of NAA coupled with Multiple $$gamma$$-ray detection (NAAMG). Its high sensitivity is demonstrated in nuclide quantification. We apply the multiple $$gamma$$-ray detection method to prompt $$gamma$$-ray analysis (Multiple Prompt $$gamma$$-ray Analysis, MPGA) by using a new $$gamma$$-ray detector array at a cold neutron beam line in Japan Research Reactor, JRR-3, at Japan Atomic Energy Agency (JAEA). In MPGA analysis we have used so far the $$gamma$$-ray double coincidence measurement. We firstly try to apply a triple coincidence measurement. The present detector system can afford the double and triple coincidence measurement as well as the singles measurement in PGA and NAA. In the presentation we compare the detection limits for those measurements. Based on the results we demonstrated that the triple $$gamma$$ coincidence is effective in some applications such as Ir concentration in rock samples. We also discuss results of applications to environmental samples.

Oral presentation

Development of swift, non-destructive, highly sensitive trace element analysis utilizing multiple $$gamma$$-ray detection method

Oshima, Masumi; Toh, Yosuke; Koizumi, Mitsuo; Kin, Tadahiro; Hara, Kaoru; Kimura, Atsushi; Furutaka, Kazuyoshi; Nakamura, Shoji; Murakami, Yukihiro*; Sushida, Kazuyoshi*; et al.

no journal, , 

A new trace element analysis method is proposed on the basis of multiple $$gamma$$-ray detection, which is two or higher fold $$gamma$$-ray coincidence method. We apply this method for prompt $$gamma$$-ray activation analysis (PGAA) and instrumental neutron activation analysis (INAA). The advantage of the methods consists of high energy resolution and high sensitivity. The principle of the multiple $$gamma$$-ray detection method and actual applications to cosmological chemistry, earth chemistry, environmental chemistry, etc, will be presented.

Oral presentation

Developments of MPGA in JRR-3 and J-PARC

Toh, Yosuke; Furutaka, Kazuyoshi; Hara, Kaoru; Harada, Hideo; Kimura, Atsushi; Kin, Tadahiro; Kitatani, Fumito; Koizumi, Mitsuo; Nakamura, Shoji; Oshima, Masumi; et al.

no journal, , 

no abstracts in English

Oral presentation

Application of multiple prompt $$gamma$$ ray analysis (MPGA) to geochemical and cosmochemical samples

Watanabe, Ryo*; Oura, Yasuji*; Ebihara, Mitsuru*; Oshima, Masumi; Toh, Yosuke; Kimura, Atsushi; Koizumi, Mitsuo; Furutaka, Kazuyoshi; Murakami, Yukihiro*

no journal, , 

no abstracts in English

Oral presentation

Completion of multiple prompt $$gamma$$-ray apparatus

Oshima, Masumi; Toh, Yosuke; Furutaka, Kazuyoshi; Murakami, Yukihiro*; Kimura, Atsushi; Koizumi, Mitsuo

no journal, , 

To achieve the new trace element analysis method of Multiple Prompt $$gamma$$-ray Analysis (MPGA) we have completed the construction of the MPGA apparatus, STELLA, at C2-3-2 beam line at the neutron guide hall in JAEA Research Reactor, JRR-3. The MPGA system made of twelve Ge detectors has been completed. A fast data acquisition system for this system has been developed. An automatic liquid nitrogen supply system for Ge detectors and an automatic sample changer enable the automatic measurement. Furthermore, rapid $$gamma$$-ray energy calibration and on-line quantification software is developed as well as necessary $$gamma$$-ray database for them. In July 2008, we have started the application of STELLA to MPGA based on the Interorganization Atomic Energy Research program by University of Tokyo, Toray Research Center and JAEA. In the talk we present the performance and status of STELLA as well as those of the apparatus at the new facility of J-PARC MLF.

Oral presentation

Generation of hard X-ray pulse in a femtosecondlaser-driven X-ray tube and its application to time-resolved spectral measurements

Yamada, Hidetaka; Murakami, Hiroshi; Shimada, Yukihiro

no journal, , 

no abstracts in English

Oral presentation

Nuclear structure study of Ni-63 using multiple prompt $$gamma$$-ray spectrometer: STELLA

Oshima, Masumi; Kin, Tadahiro; Hara, Kaoru; Nakamura, Shoji; Kimura, Atsushi; Koizumi, Mitsuo; Minato, Futoshi; Harada, Hideo; Homma, Michio*; Goto, Jun*; et al.

no journal, , 

Prompt $$gamma$$-rays from the neutron capture reaction of Ni-62 have been measured by using the multiple prompt $$gamma$$-ray spectrometer, STELLA, installed at the Research Reactor, JRR-3, of Japan Atomic Energy Agency. A highly-excited level structure below the neutron separation energy of 6838 keV in Ni-63 has been reported, including 35 new levels and 272 new $$gamma$$-ray transitions. The experimentally observed level structure is compared and discussed with a shell model calculation and a Mean-field statistical model calculation.

29 (Records 1-20 displayed on this page)