Cylindrical coordinate device simulations with a local reduction of the critical field (E-crit) by 20 % were performed to model a localized breakdown in 4H-SiC high voltage diodes with screw dislocations. The simulation results indicate no risk for second breakdown close to the onset of avalanche. Reverse recovery measurements were performed with dI/dt=1000 A/(cm(2) *mus) Up to 3000 V without failures. An enhanced reverse recovery current was observed for diodes with an increased forward voltage drop caused by DC forward conduction [1]. Simulations indicate that a high defect concentration can increase the reverse recovery current by emission of trapped carriers.