Errors Due to the Cylindrical Cell Approximation in Lattice Calculations

摘要

It is shown that serious errors in fine structure calculations may arise through the use of the cylindrical cell approximation together with transport theory methods. The effect of this approx¬imation is to overestimate the ratio of the flux in the moderator to the flux in the fuel.nIt is demonstrated that the use of the cylindrical cell approx¬imation gives a flux in the moderator which is considerably higher than in the fuel, even when the cell dimensions in units of mean free path tend to zero} whereas, for the case of real cells (e.g. square or hexagonal), the flux ratio must tend to unity.