Investigative studies on effect of reflector thickness on the performance of low enriched uranium-fueled miniature neutron source reactors

• Published in: Nuclear engineering and design 2011-08, Vol.241 (8), p.2909-2915
• Main Authors: Odoi, H.C., Akaho, E.H.K., Anim-Sampong, S., Jonah, S.A., Nyarko, B.J.B., Abrefah, R.G., Ampomah-Amoako, E., Sogbadji, R.B.M., Lawson, I., Birinkorang, S.A., Ibrahim, Y.V., Boffie, J.
• Format: Article
• Language: English
• Subjects: Applied sciences; Channels; Computer simulation; Controled nuclear fusion plants; Energy; Energy. Thermal use of fuels; Enrichment; Exact sciences and technology; Fission nuclear power plants; Fluxes; Fuels; Installations for energy generation and conversion: thermal and electrical energy; Monte Carlo methods; Nuclear engineering; Nuclear fuels; Nuclear reactor components; Reflectors
• ISSN: 0029-5493; 1872-759X
• DOI: 10.1016/j.nucengdes.2011.05.019

► Evaluation of reflector thickness required to compensate for the decrease in neutron flux due to conversion of reactor core from HEU to LEU. ► Determination of neutron flux distribution along MNSR with increased reflector thickness. ► Maintain the licensed reactivity of the Ghana Research Reactor-1, MNSR core. Neutronics analyses were performed on the 30 kW(th) GHARR-1 facility to investigate the effects on increased beryllium annular reflector thickness on nuclear criticality safety and on the neutron flux levels in the experimental channels. The investigative study was carried out using the Monte Carlo code MCNP on a hypothetical LEU UO 2 core theoretically enriched to 12.6% and having the same core configuration as the present 90.2% enriched HEU U-Al core. The analyses were performed on four models consisting of a reference model with 10.2 cm annular reflector thickness and three new design modification models with increased reflector thickness of 10.3, 10.4 and 10.5 cm respectively. The simulations indicated average thermal neutron fluxes of (9.80 ± 0.0017)E+11 n/cm 2 s in the inner irradiation channels for the reference model, indicating a 2% decrease with respect to the nominal flux of 1.00E+12 n/cm 2 s. Relatively lower neutron fluxes were obtained for the modification models with an average of (9.79 ± 0.0017)E+11 n/cm 2 s, representing losses of 2.01% and 0.01% with respect to the HEU core and reference LEU model.