In response to the 2022–2023 energy crisis, the German government postponed the phase-out of the last three nuclear plants from the end of 2022 to the 15th of April 2023. Using the ELMOD and ELTRAMOD model cluster, we compare this decision with a counterfactual scenario without German nuclear capacity and derive its implications for the integrated European electricity market. The postponement of the nuclear phase-out reduced gas-fired power generation in Europe by 2.9 TWh, with a reduction of 1.6 TWh in Germany. The substitution of expensive power plants led to a decrease of almost €9 per MWh in average electricity prices in Germany. Furthermore, carbon dioxide emissions in Germany fell by 3.3 Mt. By extending our analysis to scenarios with increased nuclear capacity and different weather years, we illustrate the limitations of large capacity blocks for managing congestion in a decentralized energy system with multiple regional grid bottlenecks.