Consider a new design of a thermal reactor that requires square arrays of fuel rods. Heat is being generated uniformly along the fuel rods. Water and helium are being considered as single-phase coolants. Relevant coolant properties are given in the Table. The design condition is that the maximum cladding surface temperature should remain below 316C. 1. Find the minimum mass flow rate of water to meet the design requirement. 2. Would the required mass flow rate of helium be higher or lower than that of water? Coolant Properties for Problem 5.3 Coolant p(kg/m) Water 735.3 Helium 0.865 Geometry of square array P = pitch = 1.5cm D = fuel rod diameter = 1.15cm H = fuel height = 3.5 m Operating conditions cp(kJ/(kg*K)) 5.317 5.225 2 Heat flux = 80 W/cm Coolant inlet temperature = 260C (kg/(m*s)) 0.955*10-4 0.298*10-4 k(W/(m*K)) 0.564 0.230