Methods in Accelerator-Driven System Dynamics

The present paper illustrates some models and methods for the kinetic evaluation of neutron multiplying systems. After introducing the general physical features of time-dependent neutronics, the simple point kinetics model is analysed, giving details on the physical meaning and mathematical structure of the equations. The spatial characterization of the neutronic transient is then investigated, with special regards to source-driven systems. It isevidenced that in a source-dominated structures, the space transients are less important than in systems departing from near criticality. The factorization technique used for quasi-static analysis is then presented and extended to source-driven systems and some considerations on the problem concerning the choice of the weghting function are made. The paper is concluded by a discussion of the physics of fluid-fuel systems, a consistent model is described and the factorization procedure is applied.