Geometrical View Factors for Radiative Heat Transfer Within Boiling Water Reactor Fuel Bundles

To calculate the radiative heat transfer between fuel bundle surfaces and from the surfaces to the vapor and droplets in a boiling water reactor, it is necessary to calculate the geometrical fuel factors. These view factors, which are the fraction of energy leaving one surface that reaches a second surface when no fluid exists, must be calculated for every pair of fuel rods, from every rod to every channel segment, and from one channel segment to a second channel segment. The crossed-string method was used to obtain algebraic equations for the view factors between rods of the same diameter, from rods-to-channel segments, and from one channel segment to a second channel segment. These equations can be easily incorporated into computer codes. Conservation of energy was used to verify the view factor equations.