Adaptive time step selection in the quasi-static methods of nuclear reactor dynamics

Highlights: • A method for the selection of the time steps in the quasi-static method is presented. • Strategies for the adaptive selection of the shape and reactivity time steps are described. • The method is applied to numerical test problems, studying the convergence behaviour. - Abstract: Of the methods available by which to integrate the neutron and delayed neutron precursor balance equations in time, at present the quasi-static methods are among the most practical and favourable. However, the correct application of the quasi-static method requires the use of appropriately determined time steps, for both the reasons of accuracy and efficiency. This work presents a methodology for the adaptive selection of the time steps employed by the quasi-static method, thereby allowing the quasi-static approach to be applied in an efficient manner while maintaining a prescribed level of accuracy. The method is applied to and studied using some numeric test problems.