Coupling of reactor power with accelerator current in ADS systems

In ADS systems, it is generally assumed that the electrical current feeding the accelerator proton beam originates from the grid. On the other hand, in an accidental event, the safety of these systems is largely based on current interruption, it being generally assumed for ADS that the required reactivity compensations during reactor operation and burn-up should be regulated through a current reserve rather than through a control rod adjustment (this avoiding inadvertent control rod removal accidents). In the case of a serious accident, if the current interruption fails, the consequences may be severe. In this work we consider an approach by which the probability of such an event is drastically reduced. Its principle is based on the coupling of the accelerator proton current, rather than with the external grid, to the electricity produced by the same reactor, except at start-up conditions, for which an external electrical current of a relatively low intensity would be used. A self-regulating mechanism, introducing an extra negative power feedback, for contributing to limiting temperature rise during transients, is also considered. The “balance of reactivity” method proposed by Wade is finally proposed for the analysis of accidental events. In an intercomparison analysis, the advantages of this approach with respect to ADS systems so far considered are discussed.