Engineered Safety Features Actuation Function

The engineered safety features include the ECCS (HPCS system, LPCS system, LPCl function of the RHR system, and the automatic depressurization function of the nuclear boiler system) and the RCIC systems. 

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Identify the problem. Remember that actuation of a protective system constitutes the occurrence but is not the real problem the unwanted, unplanned condition or action that resulted in actuation is the problem to be solved. An example of this would be when dust in the air actuates a false fire alarm. In this case, the occurrence is the actuation of an engineered safety feature. The smoke detector and alarm functioned as intended the problem to be solved is the dust in the air, not the false fire alarm. 

Nuclear power plants include engineered safety features (ESF) that initiate automatically to perform required safety functions. These safety systems allow also for operator intervention and control during operating events. Once the operator intervenes and takes manual control, many ESFs will not automatically re-initiate until the ESF is restored to a standby configuration with the actuation logic reset or rearmed. 

The DAS provides an alternate means of initiating a reactor trip and actuating specific engineered safety features in the event of a common mode iailine within the Protection and Safety Monitoring System that is, it provides diverse backup to the main protection system. The DAS has three functions diverse automatic actuation, diverse manual actuation and diverse indication of the plant information needed by the operator for a manual actuation of critical safety measures. 

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