The Isfahan Miniature Neutron Source Reactor (MNSR), as a small low-power research reactor, plays an important role in education, nuclear research, an‎d radioisotope production. Since the operational stability an‎d safety assurance of the reactor under various operating conditions are critical, accurate identification an‎d estimation of the temperature reactivity coefficient as one of the most important safety parameters are essential in the design an‎d operation of reactor. The temperature reactivity coefficient represents the amount of change in reactor reactivity due to temperature variations in different components such as fuel, coolant, an‎d structural materials. Its value is generally negative in safe reactors, an‎d precise eva‎luation of it is necessary for safety an‎d dynamical system analyses. In this study, using experimental data an‎d reactor simulation via the Monte Carlo method, the temperature reactivity coefficient of the coolant in the Isfahan Miniature Neutron Source Reactor was investigated. In the experimental method, the average reactor temperature was estimated, an‎d using changes in the control rod position, which correlate to it, the reactivity changes an‎d then the coolant temperature reactivity coefficient were estimated experimentally. In the simulation method, a complete geometric an‎d structural material modeling of the reactor was performed using the MCNP code. Then, by simulating the reactor at different coolant temperatures, the effect of temperature variation on the effective multiplication factor of the reactor was examined. Subsequently, the coolant temperature reactivity coefficients were calculated. The results show that the coolant temperature reactivity coefficient of the MNSR is effectively negative. This characteristic leads to self-stability an‎d inherent safety of the reactor under temperature an‎d power increases. The values obtained from both the experimental an‎d simulation methods show good agreement. Additionally, the calculated values correspond well with those reported in the reactor safety analysis report.

ظفراله كلانتري , جواد مختاري

ياسر عباسي دزكي , محمد حسين چوپان دستجردي

مريم حسنوند , سجاد مري