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Journal Articles

Neutron capture cross-section measurements at TC-Pn in KUR for nuclides of concern in decommissioning

Nakamura, Shoji; Endo, Shunsuke; Rovira Leveroni, G.; Kimura, Atsushi; Shibahara, Yuji*

KURNS Progress Report 2023, P. 46, 2024/07

The present work is an attempt to measure the thermal-neutron capture cross-sections for some nuclides which are of importance in decommissioning to evaluate produced radioactivity. This work selected some of objective nuclides for decommissioning, such as $$^{58}$$Fe, $$^{170}$$Er and $$^{180}$$Hf, and measured thermal-neutron capture cross-sections for these nuclides by a neutron activation method at Kyoto University Research Reactor. The present results were obtained as follows:1.23$$pm$$0.03 barn for $$^{58}$$Fe(n,$$gamma$$)$$^{59}$$Fe reaction, 8.19$$pm$$0.35 barn for $$^{170}$$Er(n,$$gamma$$)$$^{171}$$Er reaction and 13.57$$pm$$0.14 barn for $$^{180}$$Hf(n,$$gamma$$)$$^{181}$$Hf reaction. As a by-product, the measurement of Hf sample also presented 0.427$$pm$$0.006 barn for $$^{179}$$Hf(n,$$gamma$$)$$^{180}$$mHf reaction. It has been revealed that the data adopted in an evaluated data library differ from the present results by more than experimental uncertainties.

Journal Articles

Measurements of neutron capture cross-sections for nuclides of interest in decommissioning; $$^{45}$$Sc, $$^{63}$$Cu, $$^{64}$$Zn, $$^{109}$$Ag, and $$^{113}$$In

Nakamura, Shoji; Shibahara, Yuji*; Endo, Shunsuke; Rovira Leveroni, G.; Kimura, Atsushi

Journal of Nuclear Science and Technology, 16 Pages, 2024/00

Neutron capture cross-sections of nuclides targeted for decommissioning are necessary to contribute to the evaluation of radioactivity produced. The present study, $$^{45}$$Sc, $$^{63}$$Cu, $$^{65}$$Zn, $$^{109}$$Ag and $$^{113}$$In nuclides were selected as target ones, and their thermal-neutron capture cross-sections were measured by an activation method at Kyoto University Research Reactor. The thermal-neutron capture cross-sections were obtained as follows: 27.18$$pm$$0.28 barn for $$^{45}$$Sc(n, $$gamma$$)$$^{46}$$Sc, 4.34$$pm$$0.06 barn for $$^{63}$$Cu(n, $$gamma$$)$$^{64}$$Cu, 0.719$$pm$$0.011 barn for $$^{64}$$Zn(n, $$gamma$$)$$^{65}$$Zn, 4.05$$pm$$0.05 barn for $$^{109}$$Ag(n, $$gamma$$)$$^{rm 110m}$$Ag and 8.53$$pm$$0.27 barn for $$^{113}$$In(n, $$gamma$$) $$^{114}$$In$$^{m1+m2}$$. The results for $$^{45}$$Sc and $$^{64}$$Zn nuclides supported evaluated values within the limits of uncertainties, while those for the other nuclides were slightly different from evaluated ones. The obtained results are useful not only for the evaluation of production amount, but also for the monitor selection other than Au and Co by considering those nuclides as flux monitors.

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

 Times Cited Count:1 Percentile:63.33(Nuclear Science & Technology)

The thermal-neutron capture cross section ($$sigma$$$$_{0}$$) 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-$$mu$$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 $$gamma$$-ray spectroscopy. In analysis based on Westcott's convention, the $$sigma$$$$_{0}$$ and I$$_{0}$$ values were derived as 1.11$$pm$$0.04 barn and 10.5$$pm$$0.6 barn, respectively. After the $$gamma$$-ray measurements, mass analysis was applied to the Nb sample to obtain the reaction rate. By combining data obtained by both $$gamma$$-ray spectroscopy and mass analysis, the half-life of $$^{94}$$Nb was derived as (2.00$$pm$$0.15)$$times$$10$$^{4}$$ years.

Journal Articles

Neutron capture cross-section measurement by mass spectrometry for Pb-204 irradiated in JRR-3

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

Journal of Nuclear Science and Technology, 60(9), p.1133 - 1142, 2023/09

 Times Cited Count:0 Percentile:0.01(Nuclear Science & Technology)

In recent years, research has been advanced on lead-cooled fast reactors and accelerator drive systems, and it is required to improve the accuracy of the neutron capture cross section of Pb isotopes. Although $$^{204}$$Pb has a small natural abundance, it is of importance because it produces the long-lived radionuclide $$^{205}$$Pb (17.3 million years) by neutron capture reaction. However, it is difficult to measure its cross section by a conventional activation method using a nuclear reactor because the induced radioactivity of $$^{205}$$Pb is weak. Hence, the cross-section measurement was performed by applying mass spectrometry. This presentation gives the details of the experiment and the results obtained in the neutron capture cross-section measurement of $$^{204}$$Pb using mass spectroscopy.

Journal Articles

Neutron capture cross-section measurements with TC-Pn in KUR for some nuclides targeted for decommissioning

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

KURNS Progress Report 2022, P. 73, 2023/07

The present study is concerned with the neutron capture cross-sections that contribute to the evaluation of the amount of radionuclides possessing problems in decommissioning. In this study, $$^{45}$$Sc, $$^{63}$$Cu, $$^{64}$$Zn, $$^{109}$$Ag, $$^{113}$$In and $$^{186}$$W were selected among the objective nuclides, and their thermal-neutron capture cross-sections were measured using TC-Pn equipment of the KUR of the Institute for Integrated Radiation and Nuclear Science, Kyoto University. High purity metal samples were prepared. A gold-aluminum ally wire, cobalt and molybdenum foils were used to monitor the neutron flux at the irradiation position of TC-Pn. The flux monitors and metal samples were irradiated for 1 hour at 1-MW operation of the KUR. After irradiation, the irradiation capsule was opened, samples and flux monitors were enclosed in a vinyl bag one by one, and then $$gamma$$ rays emitted from the samples and monitors were measured with a high-purity Ge detector. The thermal-neutron flux component was derived with the reaction rates of flux monitors ($$^{197}$$Au, $$^{59}$$Co and $$^{98}$$Mo) on the basis of Westcott's convention, and found to be (5.92$$pm$$0.10)$$times$$10$$^{10}$$ n/cm$$^{2}$$/sec at the irradiation position. The measured reaction rate for each metal sample divided by the evaluated thermal-neutron capture cross-section should give the same value of the thermal-neutron flux component if the cross section is suitable. This time, we found that the cross sections of $$^{45}$$Sc and $$^{94}$$Zn were consistent with the evaluated one, but those of other nuclides were inconsistent with their evaluated ones; that is, it turned out that their thermal-neutron capture cross-sections should be modified.

Journal Articles

Neutron total and capture cross-section measurements of $$^{155}$$Gd and $$^{157}$$Gd in the thermal energy region with the Li-glass detectors and NaI(Tl) spectrometer installed in J-PARC$$cdot$$MLF$$cdot$$ANNRI

Kimura, Atsushi; Nakamura, Shoji; Endo, Shunsuke; Rovira Leveroni, G.; Iwamoto, Osamu; Iwamoto, Nobuyuki; Harada, Hideo; Katabuchi, Tatsuya*; Terada, Kazushi*; Hori, Junichi*; et al.

Journal of Nuclear Science and Technology, 60(6), p.678 - 696, 2023/06

 Times Cited Count:2 Percentile:48.47(Nuclear Science & Technology)

Journal Articles

Fast-neutron capture cross section data measurement of minor actinides for development of nuclear transmutation systems

Katabuchi, Tatsuya*; Iwamoto, Osamu; Hori, Junichi*; Kimura, Atsushi; Iwamoto, Nobuyuki; Nakamura, Shoji; Rovira Leveroni, G.; Endo, Shunsuke; Shibahara, Yuji*; Terada, Kazushi*; et al.

EPJ Web of Conferences, 281, p.00014_1 - 00014_4, 2023/03

Journal Articles

Thermal-neutron capture cross-section measurements of neptunium-237 with graphite thermal column in KUR

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

Journal of Nuclear Science and Technology, 59(11), p.1388 - 1398, 2022/11

 Times Cited Count:0 Percentile:0.01(Nuclear Science & Technology)

The present study selected $$^{237}$$Np among radioactive nuclides and aimed to measure the thermal-neutron capture cross-section for $$^{237}$$Np in a well-thermalized neutron field by an activation method. A $$^{237}$$Np standard solution was used for irradiation samples. A thermal-neutron flux at an irradiation position was measured with neutron flux monitors: $$^{45}$$Sc, $$^{59}$$Co, $$^{98}$$Mo, $$^{181}$$Ta and $$^{197}$$Au. The $$^{237}$$Np sample and flux monitors were irradiated together for 30 minutes in the graphite thermal column equipped with the Kyoto University Research Reactor. The similar irradiation was carried out twice. After the irradiations, the $$^{237}$$Np samples were quantified using 312-keV gamma ray emitted from $$^{233}$$Pa in a radiation equilibrium with $$^{237}$$Np. The reaction rates of $$^{237}$$Np were obtained from gamma-ray peak net counts given by $$^{238}$$Np, and then the thermal-neutron capture cross-section of $$^{237}$$Np was found to be 173.8$$pm$$4.4 barn by averaging the results obtained by the two irradiations. The present result was in agreement with the reported data given by a time-of-flight method within the limit of uncertainty.

Journal Articles

Measurements of thermal-neutron capture cross-section of the $$^{237}$$Np(n, $$gamma$$) reaction with TC-Pn in KUR

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

KURNS Progress Report 2021, P. 93, 2022/07

In terms of nuclear transmutation studies of minor actinides in nuclear wastes, the present work selected $$^{237}$$Np among them and aimed to measure the thermal-neutron capture cross-section of $$^{237}$$Np using a well-thermalized neutron field by a neutron activation method because there have been discrepancies among reported cross-section data. A $$^{237}$$Np standard solution was used for irradiation samples. The thermal-neutron flux at an irradiation position was measured with flux monitors: $$^{45}$$Sc, $$^{59}$$Co, $$^{98}$$Mo, $$^{181}$$Ta and $$^{197}$$Au. The $$^{237}$$Np sample was irradiated together with the flux monitors for 30 minutes in the graphite thermal column equipped in the Kyoto University Research Reactor. The similar irradiation was repeated once more to confirm the reproducibility of the results. After irradiation, the $$^{237}$$Np samples were quantified using 312-keV gamma-ray emitted from $$^{233}$$Pa in radiation equilibrium with $$^{237}$$Np. The reaction rates of $$^{237}$$Np were obtained from the peak net counts of gamma-rays emitted from generated $$^{238}$$Np, and then the thermal-neutron capture cross-section of $$^{237}$$Np was found to be 173.8$$pm$$4.7 barn by averaging the results obtained by the two irradiations. The present result was in agreement with the reported data given by a time-of-flight method within a limit of uncertainty.

Journal Articles

KeV-neutron capture cross-section measurement of $$^{197}$$Au with a Cr-filtered neutron beam at the ANNRI beamline of MLF/J-PARC

Rovira Leveroni, G.; Kimura, Atsushi; Nakamura, Shoji; Endo, Shunsuke; Iwamoto, Osamu; Iwamoto, Nobuyuki; Katabuchi, Tatsuya*; Kodama, Yu*; Nakano, Hideto*; Sato, Yaoki*; et al.

Journal of Nuclear Science and Technology, 59(5), p.647 - 655, 2022/05

 Times Cited Count:1 Percentile:15.09(Nuclear Science & Technology)

Journal Articles

Neutron filtering system for fast neutron cross-section measurement at ANNRI

Rovira Leveroni, G.; Iwamoto, Osamu; Kimura, Atsushi; Nakamura, Shoji; Iwamoto, Nobuyuki; Endo, Shunsuke; Katabuchi, Tatsuya*; Terada, Kazushi*; Kodama, Yu*; Nakano, Hideto*; et al.

JAEA-Conf 2021-001, p.156 - 161, 2022/03

Journal Articles

Measurements of the neutron capture cross section of $$^{243}$$Am around 23.5 keV

Kodama, Yu*; Katabuchi, Tatsuya*; Rovira Leveroni, G.; Kimura, Atsushi; Nakamura, Shoji; Endo, Shunsuke; Iwamoto, Nobuyuki; Iwamoto, Osamu; Hori, Junichi*; Shibahara, Yuji*; et al.

Journal of Nuclear Science and Technology, 58(11), p.1159 - 1164, 2021/11

 Times Cited Count:4 Percentile:54.16(Nuclear Science & Technology)

Journal Articles

Thermal-neutron capture cross-section measurement of tantalum-181 using graphite thermal column at KUR

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

Journal of Nuclear Science and Technology, 58(10), p.1061 - 1070, 2021/10

 Times Cited Count:5 Percentile:63.04(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: $$^{197}$$Au, $$^{59}$$Co, $$^{45}$$Sc, $$^{63}$$Cu, and $$^{98}$$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 $$^{181}$$Ta(n,$$gamma$$)$$^{182m+g}$$Ta reaction was measured using the graphite thermal column, and then derived to be 20.5$$pm$$0.4 barn, which supported the evaluated value of 20.4$$pm$$0.3 barn. The $$^{181}$$Ta nuclide could be useful as a flux monitor that complements the sensitivity between $$^{197}$$Au and $$^{98}$$Mo monitors.

Journal Articles

Thermal-neutron capture cross-section measurement of $$^{237}$$Np using graphite thermal column

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

KURNS Progress Report 2020, P. 94, 2021/08

The present study selected $$^{237}$$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 $$^{237}$$Np standard solution and dropped onto a fiber filter, which was then dried with an infrared lamp to prepare a $$^{237}$$Np sample. The $$^{237}$$Np sample was quantified using 312-keV gamma ray emitted from $$^{233}$$Pa in a radiation equilibrium with $$^{237}$$Np. To monitor a thermal-neutron flux component at an irradiation position, the $$^{237}$$Np sample was irradiated together with several stable nuclides as neutron flux monitors: $$^{45}$$Sc, $$^{59}$$Co, $$^{98}$$Mo, $$^{181}$$Ta and $$^{197}$$Au. The reaction rate of $$^{237}$$Np was obtained from gamma-ray yields given by $$^{238}$$Np and $$^{233}$$Pa, and then the thermal-neutron capture cross section of $$^{237}$$Np was derived.

Journal Articles

Neutron beam filter system for fast neutron cross-section measurement at the ANNRI beamline of MLF/J-PARC

Rovira Leveroni, G.; Kimura, Atsushi; Nakamura, Shoji; Endo, Shunsuke; Iwamoto, Osamu; Iwamoto, Nobuyuki; Katabuchi, Tatsuya*; Terada, Kazushi*; Kodama, Yu*; Nakano, Hideto*; et al.

Nuclear Instruments and Methods in Physics Research A, 1003, p.165318_1 - 165318_10, 2021/07

 Times Cited Count:4 Percentile:54.40(Instruments & Instrumentation)

Journal Articles

Thermal-neutron capture cross sections and resonance integrals of the $$^{243}$$Am(n,$$gamma$$)$$^{rm 244g}$$Am and $$^{243}$$Am(n,$$gamma$$)$$^{rm 244m+g}$$Am reactions

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

Journal of Nuclear Science and Technology, 58(3), p.259 - 277, 2021/03

 Times Cited Count:5 Percentile:52.06(Nuclear Science & Technology)

Research and development were made for accuracy improvement of neutron capture cross section data on $$^{243}$$Am among minor actinides. First, the emission probabilities of decay $$gamma$$ rays were obtained with high accuracy, and the amount of the ground state of $$^{244}$$Am produced by reactor neutron irradiation of $$^{243}$$Am was examined by $$gamma$$-ray measurement. Next, the total amount of isomer and ground states was examined by $$alpha$$-ray measurement. Thermal-neutron capture cross sections and resonance integrals were derived both for the $$^{243}$$Am(n,$$gamma$$)$$^{rm 244g}$$Am and for $$^{243}$$Am(n,$$gamma$$)$$^{rm 244m+g}$$Am reactions.

Journal Articles

Neutron capture cross section measurement of minor actinides in fast neutron energy region for study on nuclear transmutation system

Katabuchi, Tatsuya*; Hori, Junichi*; Iwamoto, Nobuyuki; Iwamoto, Osamu; Kimura, Atsushi; Nakamura, Shoji; Shibahara, Yuji*; Terada, Kazushi*; Tosaka, Kenichi*; Endo, Shunsuke; et al.

JAEA-Conf 2020-001, p.5 - 9, 2020/12

Journal Articles

Fast neutron capture reaction data measurement of minor actinides for development of nuclear transmutation systems

Katabuchi, Tatsuya*; Iwamoto, Osamu; Hori, Junichi*; Kimura, Atsushi; Iwamoto, Nobuyuki; Nakamura, Shoji; Shibahara, Yuji*; Terada, Kazushi*; Rovira, G.*; Matsuura, Shota*

EPJ Web of Conferences, 239, p.01044_1 - 01044_4, 2020/09

 Times Cited Count:2 Percentile:86.21(Nuclear Science & Technology)

Journal Articles

Measurement for thermal neutron capture cross sections and resonance integrals of the $$^{243}$$Am(n,$$gamma$$)$$^{rm 244g}$$Am, $$^{rm 244m+g}$$Am reactions

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

KURNS Progress Report 2019, P. 132, 2020/08

Research and development were made for accuracy improvement of neutron capture cross section data on $$^{243}$$Am among minor actinides. First, the emission probabilities of decay $$gamma$$ rays were obtained with high accuracy, and the amount of the ground state of $$^{244}$$Am produced by reactor neutron irradiation of $$^{243}$$Am was examinded by $$gamma$$-ray measurement. Next, the total amount of isomer and ground states was examoned by $$alpha$$-ray measurement.

Journal Articles

Measurement of cesium isotopic ratio by thermal ionization mass spectrometry for neutron capture reaction studies on $$^{135}$$Cs

Shibahara, Yuji*; Nakamura, Shoji; Uehara, Akihiro*; Fujii, Toshiyuki*; Fukutani, Satoshi*; Kimura, Atsushi; Iwamoto, Osamu

Journal of Radioanalytical and Nuclear Chemistry, 325(1), p.155 - 165, 2020/07

 Times Cited Count:8 Percentile:69.90(Chemistry, Analytical)

The measurements of isotopic ratios of Cs samples by thermal ionization mass spectrometry were performed for the analysis of their samples used to evaluate nuclear data obtained for $$^{135}$$Cs. To obtain a high intensity and stable ion beam, the effects of additive agents on the ionization of Cs were examined. The effect of silicotungstic acid on the ionization of Cs was the largest among the additive agents studied in the present study, while the silicotungstic acid also showed the largest isobaric interference of polyatomic ions. It was demonstrated that as small as 2$$times$$10$$^{-13}$$ g of a Cs sample was sufficient to achieve the analytical precision required to measure the $$^{135}$$Cs/$$^{137}$$Cs ratio in the case where an additive agent of TaO/glucose was employed. After examining of the analytical conditions, such as the interference effect due to Ba, the measurements of the isotopic ratios of two Cs samples used in our study using TIMS were conducted, and it was discussed how much the ratios contributed to evaluation of the neutron capture cross-section of $$^{135}$$Cs.

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