Stability Analysis of the MSBR

Abstract

The molten salt reactor is one of the six advanced reactor concepts identified by the Generation IV International Forum as a candidate for cooperative development, which is characterized by remarkable advantages in inherent safety, fuel cycle, miniaturization, effective utilization of nuclear resources and proliferation resistance. In 1971, Oak Ridge National Laboratory (ORNL) finished the conceptual design of the single fluid Molten Salt Breeder Reactor (MSBR) based on the design, building and operation of Molten Salt Reactor Experiment (MSRE). According to the conceptual design of the MSBR, a model of stability analysis using point kinetics with the motion of the precursors and coupled with the simplified heat transfer mechanism is presented. The model is validated by MSRE benchmarks and applied to simulate the power and temperature transient phenomena of the MSBR initiated by an abnormal step reactivity insertion, an abnormal ramp reactivity insertion and a period reactivity insertion at full-power equilibrium condition without external control action. The results of stability analysis for the identified three occurrences in normal operation condition show that the power is self-regulating due to the effect on fuel and graphite temperatures while the temperatures tend to new stable value. So, the negative temperature coefficients of reactivity in the MSBR make the reactor capable of stable self-regulation and the MSBR can self-stabilize to a small reactivity perturbation without any external control action.