An accident at a nuclear power plant causes the main valves to close and stop th

Question

An accident at a nuclear power plant causes the main valves to close and stop the main

water flow that cools the reactor. The control rods shut-down of the reactor, but the

radioactive fuel rods continues to release energy. The internal pressure and temperature

slowly rise to the safety limit of 100 bar causing the pressure relief valve to open and

saturated steam vapor begins to vent out of the valve.

The exit flow vented is sufficient to keep the pressure constant as long as the reactor core

remains completely flooded with saturated liquid. The liquid reserve volume above the core is

initially 120 m3

. The temperature of the core, reactor vessel and saturated liquid and

saturated vapor remain constant at the saturation temperature at 100 bar 311.1 oC while

steam is vented. The exit mass flowrate during this condition is constant at 20 kg/s. Also

assume that the heat transfer rate from the radioactive core to the liquid remains constant.

Find the mass of steam vented out from when the relief valve first opens to the point

when the water level drops below the top of the core = _________ kg and find the

change in total energy of the water/steam contained in the vessel = _________ kJ

Estimate the heat transfer rate from the core into the surrounding liquid = _________ kJ/s

NOTE: THE EXIT CONDITIONS HERE HAVE

An accident at a nuclear power plant causes the main valves to close and stop the main water flow that cools the reactor. The control rods shut-down of the reactor, but the radioactive fuel rods continues to release energy. The internal pressure and temperature slowly rise to the safety limit of 100 bar causing the pressure relief valve to open and saturated steam vapor begins to vent out of the valve. The exit flow vented is sufficient to keep the pressure constant as long as the reactor core remains completely flooded with saturated liquid. The liquid reserve volume above the core is initially 120 m3. The temperature of the core, reactor vessel and saturated liquid and saturated vapor remain constant at the saturation temperature at 100 bar 311.1 degree C while steam is vented. The exit mass flow rate during this condition is constant at 20 kg/s. Also assume that the heat transfer rate from the radioactive core to the liquid remains constant. Find the mass of steam vented out from when the relief valve first opens to the point when the water level drops below the top of the core =_____kg and find the change in total energy of the water/steam contained in the vessel=____kJ Estimate the heat transfer rate from the core into the surrounding liquid =_____kJ/s NOTE: THE EXIT CONDITIONS HERE HAVE "UNIFORM FLOW" & "UNIFORM STATE" (USUF) ANS: Delta t

Explanation / Answer

density of water is around 686 kg /m3
hence mass is 120*686=82320

exit flow rate constant at 20 kg/s

hence devide the above quantity b 20=4116 seconds=68.6 minutes

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