AN OVERVIEW OF THERMAL HYDRAULIC BEHAVIOUR OF THE FIRST NIGERIA NUCLEAR RESEARCH REACTOR (NIRR-1) MANIFESTING TO ITS INHERENT SAFETY
Publication Date : 01/08/2012
Measurements were performed to verify the thermal hydraulic behaviour of NIRR-1 under normal and transient conditions. The reactor thermal power and neutron flux parameters that result from changes in the core coolant temperatures were measured and the analysis of the data recorded showed inverse relation of the reactor power to coolant temperature. During normal operation at 31 kW (neutron flux of 1.0×1012 n cm-2s-1), the control rod gradually pulled out of the core as the inlet temperature rose from 24.8oC to 37.7oC with the corresponding outlet temperature rising from 45.1oC to 57.2oC respectively. When operated at self restraint (with control rod fully withdrawn from the core), the reactor power rose to a maximum of 75.8 kW (neutron flux of 2.59×1012 n cm-2s-1) with the corresponding inlet and outlet temperatures of 27.3oC to 62.9oC respectively and then began to drop. In both cases rise in coolant temperature results in power suppression and subsequent self shutdown which ascertained that NIRR-1 thermal hydraulic design agrees with its designed safety.
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