Nowadays, the dynamical energy market in Europe requires fast response times and advanced grid control. As a result, Francis turbine runners are subject to complex hydrodynamic forces based on low-load flow phenomena. However, transient events and in particular the turbine startup is considered as the most damaging operating condition. Therefore, experimental and numerical methods are combined to investigate the behavior of a prototype Francis turbine runner during startup. In the experimental part of the study dynamical stress is obtained by strain gauges and used to predict the runner lifetime. Additional to the conventional startup, a second scheme aiming for a higher life expectancy by reducing the opening limit is tested. The experimental part reveal high stress amplitudes during the fast opening process of the guide vanes. The reason therefore is a counter rotating draft tube vortex formation which is discovers by the use of numerical simulation. These 3 up to 4 small vortices are inducing unsteady pressure pulsations at approximately 36 Hz. With the application of the second startup schema, a reduction of the stress amplitudes of around 17% is archived. It is verified that the change of the startup schema can significantly impact the runner lifetime. (C) 2020 Elsevier Ltd. All rights reserved.