A BWR fuel assembly has a 5*5 square lattice with rod diameter of 10.2 mm and channel box inner width of 67.7 mm. Most of the fuel rods have full length of 3.7 m. Two rods have length of 1.6 and another two rods have length of 2.72 m. All the fuel rods have the same inlet level at the bottom of the fuel assembly. The reactor operates at pressure of 7 MPa with uniform rod surface heat flux, and the mass flux at the lower part of the fuel assembly is 1,260 kg/m2s. The inlet subcooling is 10.8 C and the exit quality is 0.34. There are 7 uniformly distributed spacers with interval of 0.5 m and the first spacer is located at 0.5 m from the inlet. The wet wall has roughness of 0.0023 mm and the spacer loss coefficient is 1.95 Re-0.08. Calculate the total pressure drop from inlet to outlet of the fuel assembly. Justify the methods and models you used in each step (for example, you can use HEM and WAM models).