Modernization of Digital Instrumentation and Control Systems of Ghana Research Reactor-1

Ghana Research Reactor-1 (GHARR-1) is a 30 kW tank-in-pool type reactor, which is cooled and moderated by light water and reflected by metallic beryllium blocks. It uses 90.2% enriched uranium aluminium alloy as fuel. Control of the reactor is by means of a centrally located cadmium rod cladded with stainless steel. The control of the nuclear reactor is carried out using two systems, the Control Console and the Microcomputer Closed-loop Control System (MCCS). These systems enable the control and monitoring of important parameters such as temperature and water levels to ensure the safe operation of the reactor. A new MCCS has been installed and been in operation since March 2008, through IAEA Project GHA-4-012-001N. Some modifications in the new MCCS system include the change to Microsoft Windows XP/2000 Operating System environment from DOS environment, improvement on the reliability of the electronic circuitry and the addition of other relevant monitoring parameters like reactor and pool water conductivity. The fission chamber now has an in-built power supply unit. The control rod drive mechanism and the control rod have been recently replaced. Other modifications include the creation of a large sample irradiation site and addition of beryllium shim plates. These modifications made it necessary for a recalibration of the control systems. (author)