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Np using graphite thermal columnNakamura, Shoji; Endo, Shunsuke; Kimura, Atsushi; Shibahara, Yuji*
KURNS Progress Report 2020, P. 94, 2021/08
The present study selected Np among radioactive nuclides and aimed to converge a contradiction between reported thermal-neutron capture cross sections. Neutron irradiation was carried out using the graphite thermal column equipped with the Kyoto University Research Reactor. A solution equivalent to 950 Bq order of radioactivity was pipetted out of a Np standard solution and dropped onto a fiber filter, which was then dried with an infrared lamp to prepare a Np sample. The Np sample was quantified using 312-keV gamma ray emitted from 
Pa in a radiation equilibrium with Np. To monitor a thermal-neutron flux component at an irradiation position, the Np sample was irradiated together with several stable nuclides as neutron flux monitors: 
Sc, 
Co, 
Mo, 
Ta and 
Au. The reaction rate of Np was obtained from gamma-ray yields given by 
Np and Pa, and then the thermal-neutron capture cross section of Np was derived.
Np and 
Am fission reaction rates in lead region at A-core of KUCAOizumi, Akito; Katano, Ryota; Kojima, Ryohei; Fukushima, Masahiro; Tsujimoto, Kazufumi; Pyeon, C. H.*
KURNS Progress Report 2020, P. 104, 2021/08
In the nuclear transmutation system such as ADS, the nuclear data validation of MA is required to reduce the uncertainty caused by the nuclear data of MA. This study aims to measure the fission reaction rate ratios (FRRRs) of Neptunium-237 (Np) or Americium-243 (Am) to Uranium-235 (
U) by using a single fission chambers in the KUCA. The results showed that the measured FRRRs of Np/U and Am/U were 0.048
0.003 and 0.0420.004, respectively. The measured values will be used for verification of evaluated nuclear data by conducting detailed analyses.
Mo/
Tc generator by (n, 
) method, 3Fujita, Yoshitaka; Seki, Misaki; Namekawa, Yoji*; Nishikata, Kaori; Daigo, Fumihisa; Ide, Hiroshi; Tsuchiya, Kunihiko; Sano, Tadafumi*; Fujihara, Yasuyuki*; Hori, Junichi*; et al.
KURNS Progress Report 2020, P. 136, 2021/08
no abstracts in English
Ito, Fumiaki*; Lee, J.; Hironaka, Kota; Takahashi, Tone; Suzuki, Satoshi*; Hori, Junichi*; Terada, Kazushi*; Koizumi, Mitsuo
KURNS Progress Report 2020, P. 98, 2021/08
A compact Nuclear Resonance Transmission Analysis (NRTA) system using a Laser Driven Neutron Source (LDNS) has been developed as a part of the development of nuclear non-proliferation technology supported by the MEXT. In NRTA, the neutron energy emitted from a pulsed neutron source is measured using the time-of-flight (TOF) method. LDNS is of interest because of its short pulse width, which is necessary for accurate TOF measurements over short flight distances. In the short-distance TOF measurement, there will be a large gamma-ray background event due to the coincidence of the timing of the arrival of 2.2 MeV gamma-rays due to neutron capture on hydrogen in the moderator and the timing of the arrival of neutrons around the resonance energy. Since the LDNS is still under development, the neutron flux is not sufficient and it is desirable to use a detector with high detection efficiency. For these reasons, we have developed a detector with low efficiency to gamma-rays and high efficiency to neutrons (multilayer neutron detector). As one of the results of this year's experiments, we confirmed that the multilayer neutron detector have low sensitivity to gamma-rays.
Katano, Ryota; Oizumi, Akito; Fukushima, Masahiro; Pyeon, C. H.*
KURNS Progress Report 2020, P. 102, 2021/07
For the design study of ADS, integral experimental data of LBE is necessary to validate cross sections of lead (Pb) and bismuth (Bi). In this study, we conducted Pb and Bi void reactivity measurements using aluminum (Al) void space in Kyoto University Critical Assembly (KUCA). We found that the calculations overestimate the void reactivities of Pb and Bi by about 20 pcm.
