Nuclear power plants provide the most economically efficient, safe, and sustainable source of power generation available to our generation; however it comes with it’s own set of issues that must be dealt with to mitigate any potential harm to the environment or population. One of the larger issues is that once the reactor has attained initial criticality, it is never truly “off”. The reactor will still produce heat due to decay of non-stable isotopes within it caused by fission.

Because decay heat will be forever present within a shutdown reactor, it is imperative that the ESWBR design incorporates a system to combat this heat in the event of a long shutdown period or following a SCRAM due to an adverse reactor condition. The
ADS and GDCS receive LOCA signals from Safety System Logic and Control Engineered Safety Feature (SSL/CESF). This signal is transmitted to all logic divisions and trains once the signal has been received by ECCS, the process cannot be aborted by operators.

ADS is within the NBS and serves the purpose of depressurizing the RPV so that water from the GDCS pools fan flow into it. The system contains ten Safety Relief Valves, all ten of which are Nitrogen operated solenoid actuated relief valves and eight Depressurization Valves which are electrically operated squib valves. The ADS shares a wide range transmitter with GDCS and uses a similar logic structure to accomplish it. Four logic divisions of two trains comprise the ADS. Under normal conditions two of four trains per division and two of four must give a positive vote for the system to start. A single train or division may be bypassed for maintenance and allow the system to continue operation utilizing two of three logic. This ensures a single fault will not start or prevent operation of the system. The four transmitters send initiation signals to ADS when RPV level is level 1. When the sequence first starts, 5 of the SPVs open to lower RPV pressure by emitting steam into a suppression pool, condensing the steam back into water. The other 5 open after a 10 second delay time followed by the DPVs which have a similar grouping and time delay structure. DPVs open to transfer steam