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Nakamura, Shoji; Shibahara, Yuji*; Endo, Shunsuke; Kimura, Atsushi
Journal of Nuclear Science and Technology, 11 Pages, 2023/00
Times Cited Count:1 Percentile:82.84(Nuclear Science & Technology)The thermal-neutron capture cross section () and resonance integral (I
) for
Nb among nuclides for decommissioning were measured by an activation method and the half-life of
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
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
and I
values were derived as 1.11
0.04 barn and 10.5
0.6 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
Nb was derived as (2.00
0.15)
10
years.
Nakamura, Shoji; Shibahara, Yuji*; Endo, Shunsuke; Kimura, Atsushi
Journal of Nuclear Science and Technology, 58(10), p.1061 - 1070, 2021/10
Times Cited Count:3 Percentile:51.72(Nuclear Science & Technology)In a well-thermalized neutron field, it is principally possible to drive a thermal-neutron capture cross-section without considering an epithermal neutron component. This was demonstrated by a neutron activation method using the graphite thermal column (TC-Pn) of the Kyoto University Research Reactor. First, in order to confirm that the graphite thermal column was a well-thermalized neutron field, neutron irradiation was performed with neutron flux monitors: Au,
Co,
Sc,
Cu, and
Mo. The TC-Pn was confirmed to be extremely thermalized on the basis of Westcott's convention, because the thermal-neutron flux component took a constant value regardless of the sensitivity of each flux monitor to epithermal neutrons. Next, as a demonstration, the thermal-neutron capture cross section of
Ta(n,
)
Ta reaction was measured using the graphite thermal column, and then derived to be 20.5
0.4 barn, which supported the evaluated value of 20.4
0.3 barn. The
Ta nuclide could be useful as a flux monitor that complements the sensitivity between
Au and
Mo monitors.
Shibahara, Yuji*; Uehara, Akihiro*; Fujii, Toshiyuki*; Nakamura, Shoji; Kimura, Atsushi; Hales, B. P.; Iwamoto, Osamu
JAEA-Conf 2018-001, p.205 - 210, 2018/12
In the ImPACT project, high-precision mass analysis was performed on a Cs standard solution for using
Cs included in the standard solution as an impurity to measure the
Cs cross-sections. A
Cs standard solution of only 10Bq (pg order) was analyzed, and the isotope ratio of
Cs and
Cs was obtained with an accuracy of 0.5%.
Nakamura, Shoji; Shibahara, Yuji*; Uehara, Akihiro*; Fujii, Toshiyuki*; Kimura, Atsushi; Hales, B. P.; Iwamoto, Osamu
KURRI Progress Report 2016, P. 66, 2017/07
In the ImPACT project, high-precision mass analysis was performed on a Cs standard solution for using
Cs included in the standard solution as an impurity to measure the
Cs cross-sections. A
Cs standard solution of only 10Bq (pg order) was analyzed, and the isotope ratio of
Cs and
Cs was obtained with an accuracy of 0.5%.