Determination of Epithermal Neutron Fluxes in the Cadmium-Lined Irradiation Channels of a Nuclear Reactor for Mineral Exploration

Authors

Keywords:

Reactor, Neutron flux, Highly-enriched Uranium, Low-enriched Uranium, Epithermal

Abstract

mineral deposits in soil or rock samples using method such as neutron activation analysis (NAA). Neutron flux is an important requirement for this method. Epithermal neutrons induced nuclear reactions more efficiently than with thermal neutrons when analyzing elements with high resonance integrals, it is also useful in analyzing element such as Uranium, Thorium and certain transition metals. In this study, epithermal neutron fluxes in channels of Nigeria Research Reactor-1 (NIRR-1) installed with Cadmium (Cd) were determined for use in NAA procedures. The measurements were performed after Low Enriched Uranium (LEU) fuel substituted the High enriched Uranium (HEU) fuel in the reactor. The epithermal neutron fluxes were experimentally determined using Al-0.1%Au monitor foil via 197Au(n,γ)198Au reaction. The epithermal neutron fluxes determined in the inner and outer Cd-lined irradiation channels A1 and A2 were found to be 2.539×1010 n/cm2s and 4.459×109 n/cm2s respectively at half operating power (15 kW) which corresponds to a thermal neutron flux of 5×1011 n/cm2s on the control console of NIRR-1. The values obtained before fuel conversion by previous authors in the A1-inner irradiation channel and in the A2-Outer Cd-lined irradiation channel were 2.72×1010 n/cm2s and 4.459×109 n/cm2s respectively. These values were both in agreement with the values of this study. This shows that the Cd installation and the fuel conversion from the (HEU LEU does not affect the epithermal neutron fluxes. It also implies that the stability of the neutrons in NIRR-1 were not altered. Thus, the facility is good for Epithermal NAA. The use of additional flux monitors, implementation of ENAA in geochemical analysis and evaluation of epithermal neutron shaping factor (α) were recommended.

Dimensions

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Published

2025-09-14

How to Cite

Determination of Epithermal Neutron Fluxes in the Cadmium-Lined Irradiation Channels of a Nuclear Reactor for Mineral Exploration. (2025). Nigerian Journal of Applied Physics, 1(1), 48-56. https://doi.org/10.62292/njap-v1i1-2025-20

Issue

Vol. 1 No. 1 (2025): Nigerian Journal of Applied Physics - Vol. 1 No. 1

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Articles
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How to Cite

Determination of Epithermal Neutron Fluxes in the Cadmium-Lined Irradiation Channels of a Nuclear Reactor for Mineral Exploration. (2025). Nigerian Journal of Applied Physics, 1(1), 48-56. https://doi.org/10.62292/njap-v1i1-2025-20