At its 442nd meeting, the RSK was informed by the Federal Network Agency regarding the supply security of German nuclear power plants in view of possible stability problems in the German power grid. Further consultations are to take place in the ad-hoc working group NETZ (grid) of the RSK Committee on ELECTRIC INSTALLATIONS (EL). The RSK adopted its short definition of the term "robustness" under the boundary conditions of the EU stress tests, in which the terms cliff edge effect and robustness are explained according to the definitions of the IAEA and ENSREG. A more detailed description will follow.