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Li, Y., Peng, D., Lu, J., Wu, X., Hong, J., Hao, Q., Wang, M., Odoi, H.C., Aboh, I.J.K., Amponsah-Abu, E.O., Aboh, I.J.K., Ofosu, F.G., Gyamfi, K., Osei-Mensah, W., Shitsi, E., Ampong, A.G., Quagraine, R.E., Obeng, H.K., Gasu, P.D. and Osei, B. (2017) Report for GHARR-1 Loading of LEU Core and Commissioning, National Nuclear Research Institute, Ghana Atomic Energy Commission, Kwabenya, Accra-Ghana.

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• TITLE: Validation of Neutronic and Thermal Hydraulic Parameters Displayed by the Ghana Research Reactor-1 Control System

  AUTHORS: Charlotte Anima Nketia, Edward Oscar Amponsah-Abu, Henry Cecil Odoi, Kwame Gyamfi, Isaac Kwasi Baidoo, Edward Shitsi

  KEYWORDS: Neutron Activation Analysis, Low Enriched Uranium, Neutron Flux, Temperature, Reactor Power

  JOURNAL NAME: World Journal of Engineering and Technology, Vol.13 No.3, August 8, 2025

  ABSTRACT: The accuracy of neutronic and thermal hydraulic measurement values displayed by the Ghana Research Reactor-1 (GHARR-1) control system was investigated. The reactor core underwent a conversion from High Enriched Uranium (HEU) to low Enriched Uranium (LEU). After five (5) years of operation with the new LEU core, it is necessary to validate the core parameters of the reactor to ascertain its safety for continuous operation. The conversion of GHARR-1 core from HEU to LEU caused changes in the fuel composition, which could affect reactor core parameters during operation. Hence, the neutronic and thermal-hydraulic parameters displayed by the micro-computer control system need to be validated to ascertain their reliability for experiments after 5 years of operation. The validation of the authenticity of measurements made by the GHARR-1 control system was done using the Micro Computer Closed Loop System (MCCLS). The findings demonstrated that the pre-set neutron fluxes at the control systems are 1.08 times higher than the neutron fluxes obtained using a flux monitor (cobalt) at the inner irradiation site of the reactor when the reactor is operated at different power levels of 0.17 W - 34 kW using one micro-fission chamber. The obtained fluxes’ average percentage deviations from the pre-set range (5.0 × 109 to 1.0 × 1012 ncm−2s−1) were 5.3%. When operating the reactor at the critical neutron flux of 5.0 × 109 ncm−2s−1, the core excess reactivity decreased by 7% of its nominal value of 3.87 mk. The inlet temperatures and the temperature difference across the reactor core were used to predict power levels. Results obtained show a variation in the experimental power levels as compared with the pre-set power levels giving a mean variation of 5.8%. Thus, there is agreement between the values of the neutronic parameters (pre-set power levels) displayed by the Ghana Research Reactor-1 control system and that of the experimental values determined using flux monitor and thermal-hydraulic parameters (inlet temperature and the temperature difference across the reactor core). Otherwise, appropriate reactor calibration activities and/or addition of beryllium shim to maintain the neutron flux economy for detection have to be carried out to ensure the safety of the research reactor operation.