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Ito, Chikara; Maeda, Shigetaka; Inoue, Toshihiko; Tomita, Hideki*; Iguchi, Tetsuo*
Radiation Protection, 40(6), p.491 - 495, 2020/11
A highly accurate and precise technique for measurement of the Nb(n,n')Nb reaction rate was established for the material surveillance tests, etc. in fast reactors. The self-absorption effect on the measurement of the characteristic X-rays emitted by Nb was decreased by the solution and evaporation to dryness of niobium dosimeter. A highly precise count of the number of Nb atoms was obtained by measuring the niobium solution concentration using inductively coupled plasma mass spectrometry. X-rays of Nb were measured accurately by means of comparing the X-ray intensity of irradiated niobium solution with that of the solution in which stable Nb was added. The difference between both intensities indicates the effect of Ta, which is generated from an impurity tantalum, and the intensity of X-rays from Nb was evaluated. Measurement error of the Nb(n,n')Nb reaction rate was reduced to be less than 4%, which was equivalent to the other reaction rate errors of dosimeters used for Joyo dosimetry. In addition, an advanced technique using Resonance Ionization Mass Spectrometry was proposed for the precise measurement of Nb yield, and Nb will be resonance-ionized selectively by discriminating the hyperfine splitting of the atomic energy levels between Nb and Nb at high resolution.
Sonnenschein, V.*; Tsuji, Yoshiyuki*; Kokuryu, Shoma*; Kubo, Wataru*; Suzuki, So*; Tomita, Hideki*; Kiyanagi, Yoshiaki*; Iguchi, Tetsuo*; Matsushita, Taku*; Wada, Nobuo*; et al.
Review of Scientific Instruments, 91(3), p.033318_1 - 033318_12, 2020/03
Times Cited Count:0 Percentile:0(Instruments & Instrumentation)Matsushita, Taku*; Sonnenschein, V.*; Guo, W.*; Hayashida, Hirotoshi*; Hiroi, Kosuke; Hirota, Katsuya*; Iguchi, Tetsuo*; Ito, Daisuke*; Kitaguchi, Masaaki*; Kiyanagi, Yoshiaki*; et al.
Journal of Low Temperature Physics, 196(1-2), p.275 - 282, 2019/07
Times Cited Count:1 Percentile:4.76(Physics, Applied)Sakamoto, Tetsuo*; Morita, Masato*; Kanenari, Keita*; Tomita, Hideki*; Sonnenschein, V.*; Saito, Kosuke*; Ohashi, Masaya*; Kato, Kotaro*; Iguchi, Tetsuo*; Kawai, Toshihide*; et al.
Analytical Sciences, 34(11), p.1265 - 1270, 2018/11
Times Cited Count:8 Percentile:31.98(Chemistry, Analytical)Iguchi, Tetsuo*; Hasegawa, Makoto; Takahashi, Kuniaki; Enokido, Yuji*
Dekomisshoningu Giho, (52), p.12 - 19, 2015/09
no abstracts in English
Uchida, 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:9 Percentile:40.01(Instruments & Instrumentation)Iwata, Yoshihiro; Ito, Chikara; Harano, Hideki*; Iguchi, Tetsuo*
Journal of Nuclear Science and Technology, 51(4), p.465 - 475, 2014/04
Times Cited Count:5 Percentile:36.96(Nuclear Science & Technology)To prevent a fuel failure event from becoming a serious radiation accident, sodium-cooled fast reactors are equipped with a system for failed fuel detection and location (FFDL). The FFDL instrument employed in the prototype fast breeder reactor Monju is based on the gas tagging method, in which precise and accurate measurements of krypton and xenon isotope ratios (Kr/Kr, Kr/Kr and Xe/Xe) must be performed in a short time. Burnup measurements also contribute to accurate determination of Kr/Kr. We have developed a highly sensitive resonance ionization mass spectrometer for the isotopic analyses, which uses resonance ionization of Kr and Xe atoms by a pulsed laser at wavelengths of 216.7 nm and 249.6 nm, respectively. In evaluating the performance of our spectrometer, we find that systematic errors caused by isotope shifts can be reduced to negligible levels, and that statistical errors of 3% at a nuclide concentration of 7 ppt can be achieved with a single measurement time of about 40 minutes for each Kr and Xe isotope ratio. This means that, within one hour, about 200 fuel assemblies can be individually identified with a probability of 99%, verifying the applicability of our spectrometer to the FFDL system of fast reactors.
Ishihara, 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:1 Percentile:10.69(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.
Maeda, Shigetaka; Iguchi, Tetsuo*
Journal of Nuclear Science and Technology, 50(4), p.381 - 386, 2013/03
Times Cited Count:2 Percentile:18.63(Nuclear Science & Technology)We present a new spectrum unfolding code, the Maximum Entropy and Maximum Likelihood Unfolding Code (MEALU), based on the maximum likelihood method combined with the maximum entropy method, which can determine a neutron spectrum without requiring an initial guess spectrum. The Normal or Poisson distributions can be used for the statistical distribution. MEALU can treat full covariance data for a measured detector response and response function. The algorithm was verified through an analysis of mock-up data and its performance was checked by applying it to measured data. The results for measured data from the experimental fast reactor Joyo also were compared with those obtained by the conventional J-log method for neutron spectrum adjustment. It was found that MEALU has potential advantages over conventional methods with regard to preparation of a priori information and error estimation.
Kawarabayashi, 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 0.710 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.
Maeda, Shigetaka; Iguchi, Tetsuo*
Nihon Genshiryoku Gakkai Wabun Rombunshi, 10(2), p.63 - 75, 2011/06
Neutron spectrum unfolding is a widely applied technique to characterize neutron fields for various types of reactor dosimetry, where the neutron spectrum is derived from integral measured data such as multiple-foil activation rates, moderated neutron detector counts, etc. A lot of spectrum unfolding codes have been developed so far and their performances compared to each other. However, standardized metrology for neutron spectrum unfolding is not satisfactorily established yet from the viewpoint of adequate selection and usage of unfolding codes, response function database and input data set preparation. This article reviews the present status on the neutron spectrum unfolding techniques mainly related to the reactor dosimetry with activation foils and discusses the validity of the solution spectra obtained from different kinds of unfolding codes under a typical fast reactor neutron field. The results show that the solution spectrum strongly depends on a guess spectrum required to the input data as well as the theoretical assumption in each unfolding code. The issues to improve the accuracy of reactor dosimetry are summarized on the input spectrum, nuclear database and the standardization of unfolding procedure, respectively.
Ito, Chikara; Iwata, Yoshihiro; Harano, Hideki*; Iguchi, Tetsuo*; Aoyama, Takafumi
Transactions of the American Nuclear Society, 102(1), p.416 - 417, 2010/06
no abstracts in English
Aoyama, Takafumi; Ito, Chikara; Okazaki, Koki*; Harano, Hideki*; Watanabe, Kenichi*; Iguchi, Tetsuo*
Nihon Kikai Gakkai Rombunshu, B, 75(751), p.468 - 470, 2009/03
no abstracts in English
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:0.01(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.
Aoyama, Takafumi; Ito, Chikara; Okazaki, Koki; Harano, Hideki; Watanabe, Kenichi*; Iguchi, Tetsuo*
Journal of Nuclear Science and Technology, 45(Suppl.6), p.43 - 50, 2008/09
Times Cited Count:2 Percentile:16.99(Nuclear Science & Technology)no abstracts in English
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:20.25(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.
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:29.76(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%.
Iguchi, Tetsuo*; Watanabe, Kenichi*; Kawarabayashi, Jun*; Uritani, Akira*; Enokida, Yoichi*; Watanabe, Kazuo
JAERI-Tech 2004-010, 62 Pages, 2004/03
no abstracts in English
Nishitani, Takeo; Iguchi, Tetsuo*; Ebisawa, Katsuyuki*; Yamauchi, Michinori*; Walker, C.*; Kasai, Satoshi
JAERI-Tech 2002-062, 39 Pages, 2002/07
no abstracts in English
Kobayashi, Katsuhei*; Iguchi, Tetsuo*; Iwasaki, Shin*; Aoyama, Takafumi*; Shimakawa, Satoshi; Ikeda, Yujiro; Odano, Naoteru; Sakurai, Kiyoshi; Shibata, Keiichi; Nakagawa, Tsuneo; et al.
JAERI 1344, 133 Pages, 2002/01
The JENDL Dosimetry File 99 (JENDL/D-99) has been prepared for determinations of neutron flux/fluence and energy spectrum at specific neutron fields. This file contains data for 67 reactions with 47 nuclides. Cross sections for 33 major dosimetry reactions and their covariance data were simultaneously generated and the other 34 reaction data were mainly adopted from the first version, JENDL/D-91. The GMA code was mainly used for most of the evaluation procedures by referring the basic experimental data in EXFOR. The resultant data are given in the neutron energy region below 20 MeV in both of point-wise and group-wise files in the ENDF-6 format. In order to confirm reliability of the data, several integral tests have been carried out: comparison with the data in IRDF-90V2 and average cross sections measured in fission neutron fields, fast/thermal reactor spectra, DT neutron fields and Li(d,n) neutron fields. The contents of JENDL/D-99 and the results of the integral tests are described in this report. All of the dosimetry cross sections are shown in a graphical form in the Appendix.