Pressure Drop Calculation and Analysis of Domestic New Zirconium Alloy Fuel Assembly

The pressure drop calculation of domestic new zirconium alloy fuel assembly (4×3) for pressurized water reactor was conducted. The calculation result was compared with hydraulic test’s result and the hydraulic characteristic parameters of fuel assembly were acquired. Reasonable pressure loss coefficient of grid spacer was obtained by the revision of the ratio of cross-section area of the grid spacer in the flow path to the unobstructed coolant flow area. The analysis results show that the pressure loss coefficient of grid spacer ranges from 0.660 to 1.060 under heating condition (28.0-310.0 ℃) and equals to 0.663 under high pressure and high temperature (15.3 MPa, 309.9 ℃) conditions. The pressure drop due to the four grid spacers occupies 38.9%-45.6% of the total pressure loss of the simulation fuel assembly.