Monte Carlo calculations, using the albedo concept, have been carried out to determine subcadmium and epicadmium neutron flux distributions along the centerline of a straight, a two-legged, and a three-legged square concrete duct arising from the slowing down of incident epicadmium neutrons for a particularly demanding source geometry and spectrum. The calculations used albedo data differential both in the reflected angles and reflected energy which have been reported previously for concrete. A comparison of the results of these calculations with those from a geometrically similar experiment shows good agreement and places on a firm foundation the concept of treating neutron slowing down in a concrete duct as a reflection phenomenon at a point which is describable by the differential albedo properties of the walls. The conclusion is also reached that the dose rates arising from the subcadmium neutrons (whether due to an epicadmium source or a subcadmium source) and associated secondary wall-capture gamma rays can comprise a very important part of the total absorbed dose rate in tissue deep inside a multilegged duct.