The solution of the equations describing the reactor state is obtained by numerical integration of the differential equations on an IBM-650. The general description includes the dependence of lattice constants and absorption cross sections upon the temperatures of various components and accommodates the effects of manipulations of the geometric buckling and of the total absorption cross section. The reactor kinetic equations are put into difference form suitable for numerical solution. Measures are described for eliminating divergences introduced by the numerical treatment of the coupling among temperature coefficients, delayed neutrons, and flux.