Initialising ...
Initialising ...
Initialising ...
Initialising ...
Initialising ...
Initialising ...
Initialising ...
-ray for improvement neutron emission profile measurementUchida, Yuki*; Takada, Eiji*; Fujisaki, Akihiro*; Isobe, Mitsutaka*; Ogawa, Kunihiro*; Shinohara, Koji; Tomita, Hideki*; Kawarabayashi, Jun*; Iguchi, Tetsuo*
Review of Scientific Instruments, 85(11), p.11E118_1 - 11E118_4, 2014/11
Times Cited Count：14 Percentile：49.21(Instruments & Instrumentation)Maeda, Shigetaka; Ito, Chikara; Ishihara, Kohei*; Takagi, Keisuke*; Minato, Haruna*; Sakai, Yosuke*; Kawarabayashi, Jun*; Tomita, Hideki*; Iguchi, Tetsuo*
Progress in Nuclear Science and Technology (Internet), 4, p.665 - 669, 2014/04
In order to realize neutron spectroscopy in high-intensity ray fields, an advanced nuclear emulsion based on a non-sensitized OPERA film with AgBr grain sizes of 60 nm has been developed together with a neutron spectrum unfolding method. The response functions were evaluated in the neutron energy range between 0.1 and 4.5 MeV by Monte Carlo calculations. To realize a highly reliable unfolding method that does not require an initial guess spectrum, an algorithm was formulized based on the maximum entropy principle and the maximum likelihood method, and the new unfolding code MEALU was developed. Through analyses of mock-up data, its performance was checked. The neutron spectrum from fresh fuel from the experimental fast reactor Joyo was estimated and track lengths were simulated using the calculated response function and the estimated spectrum. Comparison between the assumed neutron spectrum and the unfolded one confirmed the effectiveness of the proposed technique.
Ishihara, Kohei*; Kawarabayashi, Jun*; Tomita, Hideki*; Naka, Tatsuhiro*; Asada, Takashi*; Morishima, Kunihiro*; Nakamura, Mitsuhiro*; Maeda, Shigetaka; Iguchi, Tetsuo*
Progress in Nuclear Science and Technology (Internet), 4, p.661 - 664, 2014/04
Spent fuel emits not only neutrons but also lots of -rays by its included fission products (for example, neutron/ ratio is in the order of 10
). For its safety handling, it is important to investigate the neutron characteristics such as an emission rate, emission profile and energy spectrum. But it is difficult to measure the neutron characteristics with high precision because of lots of -rays. So the neutron characteristics are estimated by an evaluation based on its burning history. It is necessary to measure them for estimate of adequacy of the simulated result. Also, a direct measurement of the neutron characteristics is essential in the case that each spent fuel has different burning history and is mixed (for example the accident of the Fukushima Dai-ichi Nuclear Power Plant). Therefore, we develop a new nuclear emulsion in order to measure neutrons under high -rays field in our study.
-ray fields with novel nuclear emulsion techniqueIshihara, Kohei*; Takagi, Keisuke*; Minato, Haruna*; Kawarabayashi, Jun*; Tomita, Hideki*; Maeda, Shigetaka; Naka, Tatsuhiro*; Morishima, Kunihiro*; Nakano, Toshiyuki*; Nakamura, Mitsuhiro*; et al.
Radiation Measurements, 55, p.79 - 82, 2013/08
Times Cited Count：2 Percentile：16.78(Nuclear Science & Technology)In order to measure the neutron under a condition of high intensity of -ray background, we made new nuclear emulsion based on non-sensitized OPERA emulsion which had small AgBr grain size (AgBr grain size of 60, 90 and 160 nm). The sensitivity of this new emulsion, which was a correlation between stopping power and grain density, was estimated experimentally by irradiating neutrons with several energies. We also simulated the response to -ray induced electrons and compared with some experimental results by using 
Co source. The results showed that there might be a threshold energy deposited in one AgBr grain under which it was impossible to develop. We estimated efficiency to the -ray and the neutron with this obtained response of the new emulsion.
field using new type of nuclear emulsionKawarabayashi, Jun*; Ishihara, Kohei*; Takagi, Keisuke*; Tomita, Hideki*; Iguchi, Tetsuo*; Naka, Tatsuhiro*; Morishima, Kunihiro*; Maeda, Shigetaka
Journal of ASTM International (Internet), 9(3), 5 Pages, 2012/03
In order to measure the neutron from a spent fuel assembly in fast breeder reactor precisely, we made new nuclear emulsion based on non-sensitized OPERA film with AgBr grain size of 60, 90 and 160 nm. The efficiency for 
Cf neutron of the new emulsion was calculated to be 0.7
10
which energy ranged from 0.3 to 2 MeV that agrees with preliminary estimated value from experimental results. The sensitivity of the new emulsion was also estimated experimentally by irradiating 565 KeV and 14 MeV neutrons and found that the emulsion with the AgBr grain size of 60 nm showed the lowest sensitivity among these three emulsions but still had enough sensitivity for proton. Also, there was a suggestion from the experimental data that there was a threshold LET of 15 KeV/
m for our new emulsion below which no silver cluster was developed. Further development of the response of nuclear emulsion with a few tens of nano-meter AgBr size is next step of this study.
Asai, Keisuke*; Yukawa, Kyohei*; Iguchi, Tetsuo*; Naoi, Norihiro*; Watanabe, Kenichi*; Kawarabayashi, Jun*; Yamauchi, Michinori*; Konno, Chikara
Fusion Engineering and Design, 83(10-12), p.1818 - 1821, 2008/12
Times Cited Count：0 Percentile：0.00(Nuclear Science & Technology)The fuel ratio in a DT burning plasma can be derived from the intensity ratio of DD/DT neutrons, and detecting a trace of DD neutrons in the DT burning plasma is a key issue. A new type of neutron spectrometer is proposed to monitor the fuel ratio in the core of the ITER plasma. The system based on a conventional time-of-flight method consists of a water cell as a neutron scattering material and tens of scintillator pairs arranged around the first scintillator in a corn shape. We call it a multi-scattering time-of-flight neutron spectrometer (MS-TOF). A trial experiment was conducted for the prototype MS-TOF system with a DT neutron beam (20-mm diameter) at the Fusion Neutronics Source (FNS), Japan Atomic Energy Agency. The experimental results show that the DD and DT neutron peaks are clearly observed, and the experiment has successfully demonstrated the feasibility of the MS-TOF concept for detecting trace-DD neutrons within a DT neutron beam extracted from a DT burn plasma.
Naoi, Norihiro*; Asai, Keisuke*; Iguchi, Tetsuo*; Watanabe, Kenichi*; Kawarabayashi, Jun*; Nishitani, Takeo
Review of Scientific Instruments, 77(10), p.10E704_1 - 10E704_3, 2006/10
Times Cited Count：5 Percentile：28.70(Instruments & Instrumentation)The high-energy-resolution neutron spectrometry is a useful method to obtain the ion temperature and velocity distribution in nuclear fusion and/or burn plasmas. For ion temperature measurement in the ITER, we propose a promising neutron spectrometer with high-energy-resolution based on the associated particle detection using a proton recoil telescope (PRT) and a time-of-flight spectrometer (TOF). In a general PRT or TOF spectrometer, uncertainty of incident angles of recoiled protons or scattered neutrons incoming to rear detector, respectively, is a cause of deterioration of their energy resolution. In this system, no angular information is required to obtain the incident neutron energy. It is possible to enlarge the solid angles of the rear detectors subtended by the radiator to increase the detection efficiency without deterioration of the energy resolution. To verify the operational principle and the basic performance of this system, we have constructed a prototype system through Monte Carlo simulations and carried out a preliminary experiment with a deuterium-tritium neutron beam at the Fusion Neutronics Source (FNS), JAEA to obtain the energy resolution around 3.3% (in FWHM) for DT neutrons. As a result of the study for the experiment, it is expected that this system can be applied to ITER at the power within 1 order of magnitude of the maximum with measurement accuracy better than 10%.
Asai, Keisuke*; Naoi, Norihiro*; Iguchi, Tetsuo*; Watanabe, Kenichi*; Kawarabayashi, Jun*; Nishitani, Takeo
Review of Scientific Instruments, 77(10), p.10E721_1 - 10E721_3, 2006/10
Times Cited Count：3 Percentile：19.40(Instruments & Instrumentation)A time-of-flight (TOF) neutron spectrometer is one of the candidates of the measurement of the D/T burning ratio in ITER. In the ITER high power experiments, the TOF system would suffer from high event rate or accidental counts due to high radiation intensities, which can be one of background sources for DD neutron measurement. We propose a new neutron spectrometer to apply to the measurement of the D/T burning ratio in the ITER high power operation region. This system is based on the conventional double crystal TOF method and consists of a water cell and several pairs of scintillators. A water cell is inserted before the first scintillator of the TOF system and acts as a radiator or neutron scattering material. Because DD neutrons have a larger cross section of elastic scattering with hydrogen than DT neutrons, the elastic scattering in the radiator enhances the relative ratio of DD/DT intensity by about 3 times before entering the TOF system. The enhancement of the relative intensity of DD neutrons makes the detection of DD neutrons easier. The feasibility of this method as a neutron spectrometer and the basic performances of this system have been verified through a preliminary experiment using a DT neutron beam (20 mm
) at the Fusion Neutronics Source, Japan Atomic Energy Agency.
Iguchi, Tetsuo*; Watanabe, Kenichi*; Kawarabayashi, Jun*; Uritani, Akira*; Enokida, Yoichi*; Watanabe, Kazuo
JAERI-Tech 2004-010, 62 Pages, 2004/03
no abstracts in English
Tsujimura, Norio; Yoshida, T.; Kawarabayashi, Jun*; Mizuno, Ryoji*; Naka, Ryotaro*; Uritani, Akira*; Watanabe, Kenichi*
JNC TY8400 2003-010, 46 Pages, 2003/03
JNC-TY8400-2003-010.pdf:1.36MB
The authors developed a radiation distribution monitor using a normal optical fiber. This monitor has long operation length (10m - 100m) and can obtain continuous radiation distribution.
Chikamatsu, Yuma*; Hagura, Naoto*; Kawarabayashi, Jun*; Watanabe, So
no journal, ,
no abstracts in English
Chikamatsu, Yuma*; Hagura, Naoto*; Kawarabayashi, Jun*; Watanabe, So
no journal, ,
no abstracts in English
field using new nuclear emulsion, 1; OverviewKawarabayashi, Jun*; Maeda, Shigetaka; Takagi, Keisuke*; Ishihara, Kohei*; Tomita, Hideki*; Morishima, Kunihiro*; Iguchi, Tetsuo*
no journal, ,
The nuclear plate has an advantage which is a feeling of an owner as outstanding spatial resolution or a multi-radiation species, though measurement is simple at power supply needlessness. By controlling the diameter of AgBr crystalline particles in a film plate by this research, the film plate composition to which ray sensitivity was reduced was tried, and it developed aiming at the neutron precision measurement under the high ray background represented on the spent-nuclear-fuel surface etc.
field using new nuclear emulsion, 2; Recognition algorithm for recoiled proton track based on three dimensional analysis of the novel nuclear emulsionTakagi, Keisuke*; Ishihara, Kohei*; Tomita, Hideki*; Kawarabayashi, Jun*; Iguchi, Tetsuo*; Morishima, Kunihiro*; Maeda, Shigetaka; Matsumoto, Tetsuro*
no journal, ,
In the novel nuclear emulsion development to measurement a neutron spectrum in high -ray field, in order to control -ray sensitivity, the ArBr grains of about 100 nm of particle diameter is used. The recoil proton track induced by neutron is recorded on nuclear emulsion. The track constituted by a silver grains child standing in a row discretely is recorded. The track extraction algorithm suitable for extraction of recoil proton was developed, and the characteristic was evaluated.
field using new nuclear emulsion, 3; Neutron spectrum evaluation using unfolding methodMaeda, Shigetaka; Takagi, Keisuke*; Ishihara, Kohei*; Tomita, Hideki*; Kawarabayashi, Jun*; Iguchi, Tetsuo*
no journal, ,
The new style nuclear plate which controlled ray sensitivity is created, and the neutron-spectrum measurement technique under a high ray background is developed. The track length of the recoil proton of the neutron reason recorded on a nuclear plate checked that the response function was evaluated and a neutron spectrum could be evaluated by unfolding from track length since it is dependent on the energy of a neutron.
Hayashi, Shota*; Takada, Eiji*; Isobe, Mitsutaka*; Ogawa, Kunihiro*; Kawarabayashi, Jun*; Tomita, Hideki*; Iguchi, Tetsuo*; Sato, Satoshi
no journal, ,
no abstracts in English
Naoi, Norihiro*; Asai, Keisuke*; Iguchi, Tetsuo*; Watanabe, Kenichi*; Kawarabayashi, Jun*; Konno, Chikara
no journal, ,
Neutron spectrometry in a fusion reactor is a useful method to obtain the fuel ratio in the plasma core. The fuel ratio is derived from the intensity ratio of DD and DT neutron that are generated from DD and DT fusion reactions, respectively. Since the typical generation of DD neutrons is appropriately 0.5% of total neutrons, high energy resolution is important as well as detection efficiency to obtain enough SNR (Signal-to-Noise Ratio) for DD neutron detection. The design of the Associated Particle Coincident Counting Neutron Spectrometer (APCC-NS) developed to measure the ion temperature in the burning plasma was revised so that the system has an enough efficiency for DD neutrons, and the performance of the system was tested with the DD neutron beam at Fusion Neutronic Source (FNS), JAEA. As a result, a time resolution to satisfy 20% accuracy of fuel ratio measurement was obtained, but further improvement turned out to be necessary for the control of the fuel injection system.
-ray and neutron sensitivities of nuclear emulsion with AgBr nano-grainsIshihara, Kohei*; Kawarabayashi, Jun*; Tomita, Hideki*; Naka, Tatsuhiro*; Asada, Takashi*; Morishima, Kunihiro*; Nakamura, Mitsuhiro*; Maeda, Shigetaka; Iguchi, Tetsuo*
no journal, ,
In order to establish a neutron spectrum measurement in high field such as spent nuclear fuel storage, advanced nuclear emulsion based on non-sensitized OPERA film with AgBr grain size of 60 nm has been developed. A nuclear emulsion has the feature of being easy to cause latent image degradation in the high temperature condition. In this study, the experiment estimated the temperature dependency of the sensitivity to the ray and neutron of a new nuclear emulsion. It is confirmed that the detection efficiency for a neutron and fell in more than 30 
C environment.
Sakai, Yosuke*; Minato, Haruna*; Ishihara, Kohei*; Tomita, Hideki*; Kawarabayashi, Jun*; Iguchi, Tetsuo*; Naka, Tatsuhiro*; Asada, Takashi*; Morishima, Kunihiro*; Nakano, Toshiyuki*; et al.
no journal, ,
In order to measure a neutron-spectrum under high ray environment, a new nuclear emulsion and its data-processing method are developed. In fast neutron measurement using the nuclear emulsion which can record the three-dimensional track of a charged particle, incidence neutron energy spectrum can be obtained by analyzing the track of the recoil proton generated by the elastic scattering of a neutron. The high-speed automatic analytic method of the recoil proton track in a nuclear plate is developed. It checked that the recoil proton track length distribution obtained by viewing and automatic analysis was in agreement with a model calculation result about by the basic experiment using 14 MeV neutron.
Sakai, Yosuke*; Minato, Haruna*; Ishihara, Kohei*; Tomita, Hideki*; Kawarabayashi, Jun*; Iguchi, Tetsuo*; Naka, Tatsuhiro*; Asada, Takashi*; Morishima, Kunihiro*; Nakano, Toshiyuki*; et al.
no journal, ,
In order to measure a neutron-spectrum under high ray environment, a new nuclear emulsion and its data-processing method are developed. In fast neutron measurement using the nuclear emulsion which can record the three-dimensional track of a charged particle, incidence neutron energy spectrum can be obtained by analyzing the track of the recoil proton generated by the elastic scattering of a neutron. The high-speed automatic analytic method of the recoil proton track in a nuclear plate is developed. It checked that the recoil proton track length distribution obtained by viewing and automatic analysis was in agreement with a model calculation result about by the basic experiment using 14 MeV neutron.
