HGPT based sensitivity time-dependent methods for the analysis of subcritical systems

In recent years an increasing interest is observed with respect to subcritical, accelerator driven systems (ADS). Considering the attention being given to these systems for their supposed ability to play a major role as actinides incinerators, as well as power production plants, the application of the heuristically-based generalized perturbation theory (HGPT) methodology for the cycle life analysis of these systems is reviewed and commented. It is discussed in particular the role of the importance function associated with the power control, and the definition of the concept of “generalized reactivity”, merging into the standard concept of reactivity with the system approaching criticality. Basing on these results, a formulation is also described of a point kinetic equation, with physically significant coefficients, similar to those presented by Usachev in 1955 (Usachev, L.N., 1955. Atomnay a Energiya, 15, 4726), using the standard adjoint flux as weighting function.