<p>The conceptual design of Indonesia’s Research Reactor (RRI-50) core has reached the design optimization phase. RRI-50 is designed to produce the maximum neutron flux of 1.0×10<sup>15</sup> n/cm<sup>2</sup>s and thermal neutron flux of 5,0×10<sup>14</sup> n/cm<sup>2</sup>s. The analysis of design basis accident should have anticipated any possible accidents, one of which is loss of flow event that should be met according to the IAEA safety standard. There are many conditions that cause loss of flow accident, such as pump failure. This series of event may trigger an accident due to loss of coolant. Therefore, the event should be deeply analyzed. Loss of flow event analysis has been carried out using PARET-ANL code. The margin toward flow instability and two-phase flow becomes a design limit. The analysis was performed during initial period of event. The reactor scram occurred at 2.1 second because flow rate trip reaches 85% from its nominal value. Based on loss of flow event of the design basis accident of RRI-50 core, it can be concluded that the margin toward flow instability at the early transient, which is the worst condition, has not generated two-phase flow at a constant pressure.</p>
Conceptual design and initial evaluation of a neutron flux gradient detector
