The idea that SMRs are safer is yet to be proven. SMRs have a scaling issue in that a larger reactor is simply more efficient.
Solar currently can produce about 1000 Watts per square meter (likely 200-400 in practice) so 500MW of power is going to be 1-1.5 square kilometers of solar panels. You can say it's varies in effectiveness geographically. That's true. But you can build your data centers pretty much anywhere. The Sun Belt, California or Colorado spring to mind [3].
Data centers just don't need a base load. You can simply not run them when there isn't sufficient power. Google already does. Its data center in Finland basically shuts down when it gets too hot. It's otherwise cooled by the sea. This was deemed to be more efficient than having active cooling infrastructure.
So 500MW of power is what? 4B kWh/year? In California, one benchmark I found was about 10kWh/year per square foot. That's ~4 square kilometers as a very conservative estimate.
[1]: https://blog.ucsusa.org/edwin-lyman/five-things-the-nuclear-...
[2]: https://cleantechnica.com/2019/04/16/fukushimas-final-costs-...
[3]: https://neo.ne.gov/programs/stats/pdf/201_solar_leadership.p...