Analysis of the negative temperature coefficient of reactivity of the kartini reactor

TRIGA Reactors are a type of Research reactor developed by General Atomics for Training, Research, and Isotope Production. The Kartini Reactor is a TRIGA-type Reactor located in Yogyakarta, licensed to operate at 100 kW. TRIGA reactors are inherently safe due to the prompt negative temperature coefficient associated with the Fuel and Core design. The prompt negative temperature causes a decrease in power level due to the increase in fuel temperature. The phenomena allow the Kartini Reactor to operate without the primary cooling system. During reactor operations at 100 kW, the typical fuel temperature at Ring-B is around 130 °C during normal operations and around 170 °C when operated without the cooling system. This study compares and analyzes literature studies, computational calculations, and experimental results. Literature Review on the topic obtains values ranging from -9.2923×10−5 Δk/°C to -9.7419×10−5 Δk/°C for 135 °C and 180 °C, respectively. Computational calculations using MCNP obtained the value of -7.9620×10−5 Δk/°C for temperatures between 20.45 °C and 226 °C and - 1.1416×10−4Δk/°C for temperatures between 126 °C and 226 °C, which is similar to the value stated in the Safety Analysis Report for the Kartini Reactor of -1.20×10−4 Δk/°C. Experiments conducted on April 25-26th and June 20th, 2022, obtained an average result of 5.4902×10−5 Δk/°C. Hopefully, the results of this study ensure the safety of the Kartini Reactor operations.