Measurements and Calculations of Neutron Migration and its Anisotropy in Lattices of Fuel Rods and Liquid Coolant

In the design of power reactors containing lattices of fuel rods in liquid coolant, it would be useful to employ cell-averaged transport parameters reflecting anisotropic neutron migration when this is significant. Measurements and Monte Carlo calculations of anisotropic neutron migration are described for rod lattices. The well-known flux peaking near thin sources is found to be accompanied by thin source effects on migration areas. Situations of substantial migration anisotropy and thin source effects are delimited.