after a reactor shutdown using MATLAB. When all ECCS fail in a
station blackout accident, a steam generator can remove the immediate
decay heat from the fuel for a moment by evaporation of
the remaining coolant in the primary circuit. Therefore, the target
time of the hybrid heat pipe is after heat sink is no longer available.
At the target time, the amount of decay heat is about 45MW. In the
reactor transient calculation, the time considered was 3000 s after
reactor shutdown, when the hybrid heat pipe is the only way of
cooling the reactor after shutdown. Decay heat generated after
shutdown can be expressed as: