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Journal Articles

Measurements of capture cross-section of $^{93}$ Nb by activation method and half-life of $^{94}$ Nb by mass analysis

Nakamura, Shoji; Shibahara, Yuji*; Endo, Shunsuke; Kimura, Atsushi

Journal of Nuclear Science and Technology, 60(11), p.1361 - 1371, 2023/11

https://doi.org/10.1080/00223131.2023.2198526

Times Cited Count：1 Percentile：72.91(Nuclear Science & Technology)

The thermal-neutron capture cross section ( $_{0}$ ) and resonance integral (I $_{0}$ ) for $^{93}$ Nb among nuclides for decommissioning were measured by an activation method and the half-life of $^{94}$ Nb by mass analysis. Niobium-93 samples were irradiated with a hydraulic conveyer installed in the research reactor in Institute for Integral Radiation and Nuclear Science, Kyoto University. Gold-aluminum, cobalt-aluminum alloy wires were used to monitor thermal-neutron fluxes and epi-thermal Westcott's indexes at an irradiation position. A 25-m-thick gadolinium foil was used to sort out reactions ascribe to thermal-and epi-thermal neutrons. Its thickness provided a cut-off energy of 0.133 eV. In order to attenuate radioactivity of $^{182}$ Ta due to impurities, the Nb samples were cooled for nearly 2 years. The induced radio activity in the monitors and Nb samples were measured by -ray spectroscopy. In analysis based on Westcott's convention, the $_{0}$ and I $_{0}$ values were derived as 1.110.04 barn and 10.50.6 barn, respectively. After the -ray measurements, mass analysis was applied to the Nb sample to obtain the reaction rate. By combining data obtained by both -ray spectroscopy and mass analysis, the half-life of $^{94}$ Nb was derived as (2.000.15)10 $^{4}$ years.

Journal Articles

Development of correction method for sample density effect on PGA

Maeda, Makoto; Segawa, Mariko; Toh, Yosuke; Endo, Shunsuke; Nakamura, Shoji; Kimura, Atsushi

Journal of Radioanalytical and Nuclear Chemistry, 332(8), p.2995 - 2999, 2023/08

https://doi.org/10.1007/s10967-023-08961-x

Times Cited Count：0 Percentile：0.01(Chemistry, Analytical)

Journal Articles

Improved experimental evaluation and model validation of a $^{252}$ Cf irradiator for delayed gamma-ray spectroscopy applications

Tohamy, M.*; Abbas, K.*; Nonneman, S.*; Rodriguez, D.; Rossi, F.

Applied Radiation and Isotopes, 173, p.109694_1 - 109694_7, 2021/07

https://doi.org/10.1016/j.apradiso.2021.109694

Times Cited Count：5 Percentile：65.59(Chemistry, Inorganic & Nuclear)

Journal Articles

Bias effects on g- and s-factors in Westcott convention

Harada, Hideo

Applied Sciences (Internet), 11(14), p.6558_1 - 6558_20, 2021/07

https://doi.org/10.3390/app11146558

Times Cited Count：0 Percentile：0(Chemistry, Multidisciplinary)

For accuracy improvement of neutron activation analysis and neutron capture cross section, bias effects are investigated on g- and s-factors in the Westcott convention. As origins of biases, a joining function shape, neutron temperature and sample temperature, have been investigated. Biases are quantitatively deduced for two 1/v isotopes ( $^{197}$ Au, $^{59}$ Co) and six non-1/v isotopes ( $^{241}$ Am, $^{151}$ Eu, $^{103}$ Rh, $^{115}$ In, $^{177}$ Hf, $^{226}$ Ra). The s-factor calculated with a joining function deduced recently by a detailed Monte Carlo simulation is compared to s-factors calculated with traditional joining functions by Westcott. The results show the bias induced by sample temperature is small as the order of 0.1% for g-factor and the order of 1% for s-factor. On the other hand, biases induced by a joining function shape for s-factor depend significantly on both isotopes and neutron temperature. As the result, reaction rates are also affected significantly as well. The bias size on reaction rate is given in the case of epithermal neutron index r = 0.1, for the eight isotopes.

Journal Articles

A New convention for the epithermal neutron spectrum for improving accuracy of resonance integrals

Harada, Hideo; Takayama, Naoki; Komeda, Masao

Journal of Physics Communications (Internet), 4(8), p.085004_1 - 085004_17, 2020/08

https://doi.org/10.1088/2399-6528/aba735

A new convention of epithermal neutron spectrum is formulated for improving accuracy of resonance integrals. The new type function is proposed as an approximating function of epithermal neutron spectrum based on calculations by the state-of-art Monte Carlo code MVP-3. Bias effects on determination of resonance integrals due to utilizing approximating functions of the traditional types and the new type are compared. The other bias effect is also investigated, which is caused by neglecting position dependence of a neutron spectrum inside an irradiation capsule. For demonstrating the bias effects due to these assumptions on neutron spectrum quantitatively in a practical case, the thermal neutron-capture cross section and resonance integral of $^{135}$ Cs measured at a research reactor JRR-3 are re-evaluated. A superior property of the proposed new convention is discussed. The experimental method is proposed to determine the new shape factor introduced in the convention by a combinational use of triple flux monitors ( $^{197}$ Au, $^{59}$ Co and $^{94}$ Zr), and its analytical methodology is formulated.

Journal Articles

R&D of active neutron NDA techniques for nuclear nonproliferation and nuclear security, 3; Validation of neutron transport code for design of NDA system

Maeda, Makoto; Komeda, Masao; Tobita, Hiroshi; Ozu, Akira; Kureta, Masatoshi; Bogucarska, T.*; Crochemore, J. M.*; Varasano, G.*; Pedersen, B.*

Dai-37-Kai Kaku Busshitsu Kanri Gakkai Nihon Shibu Nenji Taikai Rombunshu (CD-ROM), 7 Pages, 2017/02

JAEA and EC/JRC are carrying out collaborative research to develop NDA techniques that can be utilized for quantification of high radioactive special nuclear materials such as spent fuel and next generation minor actinide fuels. In the research, reliability of neutron transport codes is important because it is utilized for design and development of a demonstration system of next-generation Differential Die-away (DDA) technique in JAEA. In order to evaluate the reliability, actual neutron flux distribution in a sample cavity was examined in PUNITA device using JRC type DDA technique and JAWAS-T device using JAEA type DDA technique, and then the measurement results were compared with the simulation results obtained by the neutron transport codes. The neutron flux distribution in the target matrix was also examined in the PUNITA and compared with the simulation results. We report on the measurement and simulation results of the neutron flux distribution and evaluation results of the reliability of the neutron transport codes.

Journal Articles

Evaluation of neutron flux distribution in the JAEA type and JRC type DDA systems

Maeda, Makoto; Komeda, Masao; Tobita, Hiroshi; Ozu, Akira; Kureta, Masatoshi; Bogucarska, T.*; Crochemore, J. M.*; Varasano, G.*; Pedersen, B.*

Proceedings of INMM 57th Annual Meeting (Internet), 9 Pages, 2016/07

The JAEA and EC/JRC have started collaborative research to develop a technique that can be utilized for quantification of high radioactive special nuclear materials such as next generation minor actinide fuels. In the study of a Differential Die-Away (DDA) technique, which is one of the techniques to be improved in the collaborative research, JRC type and JAEA type DDA techniques are compared. In the JRC type DDA technique, large amount of thermal neutron is generated using D-T neutron generator and graphite moderator to accomplish high detection sensitivity for small amount of fissile material. On the other hand, in JAEA type, relatively hard neutron spectrum and moderation of neutron in the target matrix are utilized to minimize position dependence of detection efficiency. Estimation of the neutron field is important to evaluate the performance of the system in DDA technique. The purpose of this study is to validate simulation results by experimental results and evaluate neutron flux distribution in the system by the simulation and the experiment. In this paper, we present the evaluation results of the neutron flux distributions in PUNITA which utilizes JRC type DDA technique and JAWAS-T which utilizes JAEA type DDA technique obtained by Monte Carlo simulation and activation method.

Journal Articles

Analysis of sequential charged particle reaction experiments for fusion reactors

Yamauchi, Michinori*; Hori, Junichi*; Ochiai, Kentaro; Sato, Satoshi; Nishitani, Takeo; Kawasaki, Hiromitsu*

Fusion Engineering and Design, 81(8-14), p.1577 - 1582, 2006/02

https://doi.org/10.1016/j.fusengdes.2005.09.066

Times Cited Count：1 Percentile：9.98(Nuclear Science & Technology)

no abstracts in English

Journal Articles

Irradiation effects on precipitation in reduced-activation ferritic/martensitic steels

Tanigawa, Hiroyasu; Sakasegawa, Hideo*; Klueh, R. L.*

Materials Transactions, 46(3), p.469 - 474, 2005/03

https://doi.org/10.2320/matertrans.46.469

Times Cited Count：20 Percentile：73.88(Materials Science, Multidisciplinary)

The effects of irradiation on precipitation of reduced-activation ferritic/martensitic steels (RAFs) were investigated, and its impacts on the Charpy impact properties and tensile properties were discussed. It was previously reported that RAFs (F82H-IEA and its heat treatment variant, ORNL9Cr-2WVTa, JLF-1 and 2%Ni doped F82H) shows variety of changes on its ductile-brittle transition temperature (DBTT) and yield stress after irradiation at 573K up to 5dpa. These differences could not be interpreted as an effect of irradiation hardening caused by dislocation loop formation. The precipitation behavior of the irradiated steels was examined by weight analysis, X-ray diffraction analysis and chemical analysis on extraction residues. These analyses suggested that irradiation caused (1) the increase of the amount of precipitates (mainly M $_{23}$ C $_{6}$ ), (2) increase of Cr and decrease of W contained in precipitates, (3) disappearance of MX (TaC) in ORNL9Cr and JLF-1.

Journal Articles

Determination of traces of arsenic and antimony in certified reference steel samples by neutron activation analysis with multiple -ray detections

Kimura, Atsushi; Oshima, Masumi

Tetsu To Hagane, 90(12), p.1004 - 1009, 2004/12

http://joi.jlc.jst.go.jp/JST.Journalarchive/tetsutohagane1955/90.1004

no abstracts in English

JAEA Reports

Proceedings of the FNCA 2002 Workshop on the Utilization of Research Reactors; January 13-17, 2003, Jakarta & Serpong, Indonesia (Contract research)

Nuclear Technology and Education Center

JAERI-Conf 2004-010, 236 Pages, 2004/06

JAERI-Conf-2004-010.pdf:14.82MB

The FNCA 2002 Workshop on the Utilization of Research Reactors, which is the eleventh workshop on the theme of research reactor utilization, was held in Jakarta and Serpong, Indonesia from January 13 to 17. This workshop was executed based on the agreement in the third Coordinator's Meeting of Forum for Nuclear Cooperation in Asia (FNCA) held in Tokyo, March 2002. The workshop consists of two groups under the theme of the following fields; 1) Tc-99m Generator Technology, 2) Neutron Activation Analysis. The total number of participants for the workshop was 88 people from 8 countries; China, Indonesia, Korea, Malaysia, the Philippines, Thailand, Vietnam and Japan. This report consists of 8 papers from the plenary session, 10 papers for Tc-99m Generator, 10 papers for Neutron Activation Analysis and a summary report.

Journal Articles