Measurement of control rod reactivity and shut down margin of 3 MW TRIGA Mark-II research reactor using analogue and digital I&C system

• Measurement of reactor safety parameters is essential for operational safety.
• Control rod reactivity, shut down margin and core excess reactivity were measured.
• Measured values were found within the safety limit of BAEC research reactor.
• Results are in good agreement with the digital and analogue I&C system.

Measurement of reactor safety parameters is essential for reactor safety, operation and experimental research. Reactor control rod reactivity has been measured by the positive period method using analogue and digital instrumentation & control (I&C) system of the 3 MW TRIGA Mark-II research reactor of Bangladesh Atomic Energy Commission (BAEC). The BAEC research reactor had been operating with the analogue I&C system since September 1986–July 2011. The analogue I&C system has been replaced by a new digital I&C system on June 2012 and the reactor is now operating with the PC based digital I&C system. In the newly installed digital I&C system several modifications, upgradations and replacement tasks were carried out including control rod drive systems. After the installation of the digital I&C system, some nuclear safety parameters (e.g., control rod worth, core excess reactivity and shut down margin) were measured to ensure the safe operation of the reactor. In this study, the measured control rod reactivity, core excess reactivity and shut down margin were also compared with the previous measured (analogue system) values for the validation of the digital I&C system of the reactor. The measured safety parameters were found within the safety limit as mentioned in the safety analysis report (SAR) of the BAEC research reactor.