Thermal-hydraulic modeling of reactivity accident in MTR reactors

This paper describes the development of a dynamic model for the thermal-hydraulic analysis of MTR research reactor during a reactivity insertion accident (RIA). The model is formulated for coupling reactor kinetics with feedback reactivity and the reactor core thermal-hydraulics. Two channels are considered: the average and the hot channels to represent the reactor core. The developed computer program is compiled and executed on a personal computer using the FORTRAN language. The model is validated by safety-related benchmark calculation for MTR-Type reactors of IAEA 10 MW generic reactor for both slow and fast reactivity insertion transients [IAEA-TECDOC, 1980. Research Reactor Core Conversion from the use of Highly Enriched Uranium to the use of Low Enriched Uranium Fuels, Guidebook. Tecdoc, 233, Tecdoc, 643]. A good agreement is shown between the present model and the benchmark calculations. Then, the model is used for simulating uncontrolled withdrawal of a control plate of ETRR-2 for both transients: transient with over power scram trip and self-limited transient. The model results for ETRR-2 were analyzed and discussed.