The Determination of Lattice Parameters by Means of Measurements on a Single Fuel Element

The four-factor critical equation for a heterogeneous thermal reactor is looked at in detail. It is then written in terms of parameters which characterize separately the fuel element, the moderator, and the lattice cell geometry of a heterogeneous thermal reactor. Methods for determining the parameters are then discussed. The results of measurements and analysis for two different fuel element types are compared with the results of measurements made on full lattices consisting of these fuel elements.