Purposes and designs of reactor protection systems

Whenever failures or faults occur which cannot be controlled by operational or limiting measures, the reactor protection system is to maintain the plant in a safe condition by initiating safety systems. In German nuclear power plants, faults are indicated by the occurrence of at least two physically different initiation criteria. They are recognized by a process variable exceeding set limits in the reactor protection systems. Protective measures are largely automated and relieve the plant personnel of the need to take fast action. The safety installations of the reactor protection system have priority over the reactor safety system, unless this would cause damage detracting from the safety of the plant. Even under the assumption of worst conditions, the design of the reactor protection system safely controls fault conditions in line with the stringent standards laid down in German rules and regulations.