The Institute for Science and International Security has a small report on satellite imagery where they isolate a possible reactor site in Syria.

I'm not familiar with the group, and obviously, they're only making informed guesses, so take it for what it's worth.

One way to ace this would be current pictures of this site showing bombing damage, and no doubt the military has a full supply of spysat pictures of the bombed site (wherever it actually is). But the most recent photos available to the public are from the middle of August. I don't know how often they update this stuff.

As they mention in the report, simply pulling this site up on Google Earth and zooming in (coordinates below) does not show all of the construction that is apparently visible if you pay to order the "DigitalGlobe" photo they used in the report (Figure 1).

Interestingly, when you switch on the "DigitalGlobe Coverage" markings on Google Earth, showing all the satellite photo frames, there seems to be a large conglomeration of them from August in this vicinity.

The "reactor" building coordinates:

Latitude: 35° 42' 31.02" N

Longitude: 39° 49' 58.50" E