Evaluation of neutronic safety parameters of the BAEC TRIGA Research Reactor with Wet Central Tube

Highlights: • The control rod worth, core excess reactivity and shutdown margin have been measured. • Reactivity change is low with each control rod movement when the CT is filled with water. • The core excess reactivity decreases with increasing water height in the central tube. • BTRR reactivity worth with WCT is large enough to make the reactor shutdown at any condition. - Abstract: Nuclear safety and controlling system is a prime issue for the operation of a nuclear reactor. Control rod worth is one of the important neutronic safety parameters to ensure the safe operation of a nuclear reactor and experimental research. Control rod reactivity depends on neutron flux of the core and core configuration of a reactor. In this study, the control rod reactivity, core excess reactivity and shutdown margin with Wet Central Tube (WCT) of the BAEC TRIGA Research Reactor (BTRR) have been measured. The change of reactivity with the change of water height in the central tube has also been investigated in this study. The measured control rod reactivity, core excess reactivity and shutdown margin with WCT are then compared to those with the Dry Central Tube (DCT). The total worth of control rod of BTRR with DCT and WCT have been found to be 16.96 $ and 15.99 $ respectively at 775 MWds burn up. The values of the core excess reactivity and shutdown margin are found as 6.62 $ and 6.29 $ respectively for WCT, and 7.34 $ and 6.12 $ for DCT at 100 W reactor power level. It has been observed that the core excess reactivity decreases with increasing water height in the central tube of the reactor core. On the other hand, the shutdown margin increases with increasing water level. The values of the control rod worth, core excess reactivity and shutdown margin have been found to be within the safety limit as recommended in the General Atomic (GA) Safety Analysis Report (SAR) of BTRR.