Thus, if the operator actions are not appropriate, it is possible a transition from a design accident to a severe accident and after some time the NPP will be without any emergency water.
The purpose of the analysis is to demonstrate the ability to terminate primary to secondary leakage and indicate an effective strategy of operator actions for preventing secondary leakage to the environment and this way to prevent radiological release to the environment.
A double-ended single pipe break and double-ended break of two pipes in SG #6 have been chosen as representative. The reason for investigation of both cases is to understand influence of increasing of break flow rate from primary to secondary side on progression of accident scenario. In addition, it has been performed to simulate two different strategies to operator emergency procedure to stability the plant without any uncover of the core.
The used model () has been developed at the Institute for Nuclear Research and Nuclear Energy, Bulgarian Academy of Sciences (INRNE-BAS), Sofia, for analyses of operational occurrences, abnormal events, and design bases scenarios. The model provides a significant analytical capability for specialists working in the field of NPP safety.