Safety analysis emergency electrical systems

The effects of flooding on a nuclear power plant site may have a major bearing on the safety of the plant and may lead to a postulated initiating event (PIE) that is to be included in the plant safety analysis. The presence of water in many areas of the plant may be a common cause of failure for safety related systems, such as the emergency power supply systems or the electric switchyard, with the associated possibility of losing the external connection to the electrical power grid, the decay heat removal system and other vital systems. Details are provided in Ref [6]. 

The necessity for engineered safety features shall be determined from the safety analysis. The accidents with which these systems must be able to cope shall be specified and analyses shall be provided to demonstrate that the systems fulfil the requirements. Those systems and subsystems that are essential for the proper operation of the engineered safety features shall be provided (e.g. the emergency electrical power supply for the emergency core cooling system). 

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