Measurement and calculation of the void reactivity coefficient of the Jordan research and training reactor (JRTR)

• Core Design Characteristics of the JRTR. • Evaluation Method of the Void Reactivity Coefficient. • Measurement and Calculation Results. The void reactivity coefficient for the JRTR was evaluated experimentally, and the voids in the reactor core were simulated using the specially designed tools of aluminium. These simulators were inserted vertically into the coolant channel between the fuel plates, in the central area of the fuel assembly. The experiments were performed for the scenarios with 4.74 %, 2.37 %, 0 % of void fractions within the reactor core, and a series of calculations for these experiments were performed by using McCARD code with the ENDF/B-VII nuclear library. The results of the calculations for the CARs critical position show good agreement with the corresponding measurement results within 1.8 mm. Also, the void reactivity coefficient in all experiments had negative values, and the coefficient for the JRTR was experimentally evaluated to be −0.237 $/% void.