Dynamic Simulation of LMFBR Plant under Natural Circulation

Dynamic simulation of the entire LMFBR plant is needed to determine after-heat dissipation capability of the plant via natural circulation. Models required to accomplish this task are briefly described. The resulting computer code, Super System Code-Loop (SSC-L), is then applied to a loop-type fast reactor design to illustrate the system response for a loss-of-electric-power event. Where possible, the Clinch River Breeder Reactor Plant (CRBRP) specifications are used. Entire simulation is performed for up to 1800 seconds of the transient time. Even with rather detailed modeling of essential components, the computing time required on the CDC-7600 machine was slightly less than the real time. For the assumed plant conditions, it is found that the decay heat is adequately removed via natural circulation. The effect of advanced modeling on system performance is also demonstrated. Finally, a scenario of an event that could impose more stringent testing of the plant’s capability for adequate dissipation of decay heat is described.