[ RadSafe ] Reactor safety for passive

[sfisher373 at aol.com]

>From wikipedia"Passive nuclear safety is a design approach for safety features, implemented in a nuclear reactor, that does not require any active intervention on the part of the operator or electrical/electronic feedback in order to bring the reactor to a safe shutdown state, in the event of a particular type of emergency (usually overheating resulting from a loss of coolant or loss of coolant flow)."

This has nothing to do with plugs at the bottom of the reactor.
Re Candu. "To illustrate this point the answer included a diagram of a CANDU reactorbut I did not see the supposed meltable plugs in the floor or the sumps."
You are correct that there are no meltable plugs in the floor.  Re sumps, the original CANDU at Pickering A were built with a dump system into dump tanks.  This was an error in safety, as the moderator acts as a coolant in the case of a Loss of Cooling accident.  
All Candu's are built with three fast shutdown systems, Liquid Zone Control, Shut off rods, and moderator poison.  However, Candu's as built are not passive.  
Spencer FisherOPG retired, Nuclear Theory and Reactor Physics, Authorized Training.