Calculation of reactivity in subcritical reactors using the method of partial derivatives

The analysis of source-driven subcritical reactors is of great interest as it allows savings in the mineral resources used in their cores, due to the possible transmutation of nuclear fuel burned in critical reactors. In ADS (Accelerator Driven System) reactors the neutrons produced from spallation reactions generate an source, external to the core, that supports its operation. Although there are different formalisms to describe the kinetic behaviour of these reactors, its functioning remains an open question, as there is no ADS reactor in operation. Thus, with the aim of predicting reactivity behaviour in this type of reactor, the inverse point kinetics equation was obtained, using a specific formalism for subcritical reactors. The results obtained were compared to Monte Carlo simulations for the purposes of validation and were shown to be coherent, displaying deviations under 100 pcm.