Engineering safety feature actuation systems ESFAS

ESF Engineered Safety Feature Actuation System ESFAS... 

The next point which makes the digital solution more vulnerable from common causes is eventual aggregation of different safety systems automation into one actuation system - e.g. Reactor Trip System (RTS) and Engineered Safety Features Actuation System (ESFAS), RTS + Reactor Limitation System C S). 

The Plant Protection System (PPS) consists of the Reactor Protection System (RPS) and the Engineered Safety Features Actuation System (ESFAS) (see CESSAR-DC Section 7.1.1.1). 

The System 80+ Standard Design has a Main Feedwater Isolation System (see CESSAR-DC Section 10.4.7.2.2) to protect the SGs from overfill. The system includes redundant remotely operated isolation valves in each main feedwater line to each SG. The valve actuation system (see CESSAR-DC Section 7.3.1.1.10.3) is composed of redundant trains A and B, and each train s instrumentation and controls are physically and electrically separate from and independent of those of the other train. A failure of one train will not impair the action of the other. The main feedwater isolation valves are automatically actuated by a Main Steam Isolation Signal (MSIS) from the Engineered Safety Features Actuation System (ESFAS, see CESSAR-DC Section 7.3.1). High SG water level, in a 2-out-of-4 logic, is one of the initiators for the MSIS. The main feedwater isolation valves can be in-service tested in accordance with ASME Code Section XI, Subsection IWV. A Technical Specification (CESSAR-DC Chapter 16) will establish testing requirements for the valve actuation system. These requirements will also be incorporated into the plant maintenance procedures. 

Engineering safety feature actuation systems (ESFAS)... 

The characteristics in this group identify the systems used to maintain reactor core cooling if there is a loss of the normal reactor coolant. These systems usually include both active and passive systems (safety injection pumps and core flooding hydroaccumulators). Safety injection pumps should be considered as such pumps if they can be automatically started by an Engineered Safeguard Feature Actuation System (ESFAS) or a similar safety signal. 

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