Thermal-Neutron capture cross-section measurements of Neptunium-237 with graphite thermal column in KUR. Issue 11 (2nd November 2022)

• Record Type: Journal Article
• Authors: Nakamura, Shoji; Shibahara, Yuji; Endo, Shunsuke; Kimura, Atsushi
• Is Part Of: Journal of nuclear science and technology. Volume 59:Issue 11(2022)
• Page Start: 1388
• Page End: 1398
• Publication Date: 2022-11-02
• Subjects: Neptunium-237 -- protactinium-233 -- radiation equilibrium -- nuclear transmutation -- thermal-neuron capture cross-section -- neutron activation method -- graphite thermal column -- kyoto university research reactor; Nuclear engineering -- Periodicals; Nuclear physics -- Periodicals; Nuclear energy -- Periodicals; 621.4805
• DOI: 10.1080/00223131.2022.2058639
• Languages: English
• ISSNs: 0022-3131

Abstract

ABSTRACT: 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 ± 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. Abstract : uf0001