The future power grid comprises large shares of inverter-based resources (IBRs) dominated by solar and wind power. As a result, the grid's resilience in terms of voltage and frequency regulation capabilities can be significantly reduced. To deal with this unsolved challenge, there is a potential for small modular reactors (SMRs) to provide, in addition to electricity and heat, system-bearing services that, at a reduced cost, can enable higher penetration of renewables. This paper shows that the alternative system-wide ancillary service cost for physical inertia and short-circuit capacity can be approximately $20/MWh when using synchronous condensers (SCs) to enable a 100 % renewable energy system. SMRs can avoid these additional system costs and, in addition, significantly increase the grid strength when compared to the use of SC devices. Moreover, it is shown that multiple SMR units instead of large nuclear power plants significantly reduce the needed frequency reserves.