[en] In this thesis the theory of fuel cycle kinetics is re-examined. The fuel cycle kinetics theory is a powerful tool to describe the time-dependent fuel behaviour of large populations of nuclear reactors. The fuel cycle kinetics theory is based on the point kinetics theory and the principles of a reactor park. The point kinetics theory is a simplification of the space-, energy-and time-dependent diffusion balance equation to only a time-dependent equation. A reactor park is the description of the interconnections between a population of nuclear reactors with various designs. In the fuel cycle kinetics theory the point kinetics theory is used as a model to simplify space- energy- and time-dependent burn-up equations of the reactors in a reactor park to a set of only time-dependent equations, one for every reactor type. The fuel cycle kinetics theory is verified by means of a number of test cases. In the first test case the same symbiotic system is used as was used by Maudlin. There is no difference between the two obtained results. The second test case is that of only Fast Breeder Reactor, FBR, deployment. Here the result of the fuel cycle kinetics equation is checked against the result obtained from TRITON. TRITON is a module of the SCALE code system that is used for depletion analysis of 3-D reactor models. With the use of the pseudo-initial condition the results of the fuel cycle kinetics and TRITON calculations are almost identical. The pseudo-initial condition is a correction on the initial condition to adjust for neglecting the time dependency of the parameters in the fuel cycle kinetics equations. In the third case a symbiotic system of FBRs and Pressurised Water Reactors, PWRs, is researched. There is only a small difference in the asymptotic growth between the fuel cycle kinetics results and the TRITON results. In the last test case the same system of FBRs and PWRs is used to investigate two demanded asymptotic growths obtained from the upper and lower boundary of the expected growth of nuclear reactors in the upcoming years. Two iteration steps on the coupling matrices in the fuel cycle kinetics equations were needed to reach these asymptotic growths. The results obtained from the last iteration in the fuel cycle kinetics equations are almost identical to the results obtained from the TRITON calculations with the coupling obtained from the iteration. The test cases demonstrate that the expectations of the theory of being computationally cheap and accurate in predicting the fuel behaviour of nuclear reactor populations over longer time spans are correct. (author)