A PWR is operating at a steady state condition. We now shutdown the plant and want to estimate the natural circulation flow rate. Although the reactor power decays after shutdown, we assume the core power remains steady for the duration of interest. Find the natural circulation flow rate 48 hours after shutdown. Data: Nominal reactor power: 3000 MWth, reactor pressure: 2265 psia, T_c = 550 F, TH = 610 F, ΣR = 0.28 ft^-4.