3. Calculate hydraulic (D) or hydraulic-equivalent diameter (Dhy) (see Chapter 6) for the following flow geometries: Rod of OD 10 mm is installed inside square cross-section channel with inside dimension of 20 mm; Flow is in the area between square channel and rod. 012- Flow channel - blue color Inside rod OD 5.2 mm Pressure tube ID 8.4 mm Rod equipped with 4 fins: height 0.6 mm and width 1 mm 08.4 18- Dh or Dhy = Page < 3 > of 6 C ZOOM + Pressurized Water Reactor has vertical cylindrical pressure vessel with inside diameter of 2.88 m in which 349 bundle strings or fuel assemblies are installed vertically. Each bundle string consists of 126 fuel rods of outside diameter 9.1 mm. 33 Dh or Dhy = Page < 4 > of 6 C ZOOM +