I read this on the Independent today: "US claims photos show Syrian nuclear reactor". I find that hard to believe. Here is the image and location of the site as shown in the ISIS-Online report.
The image was available on Google Earth and when I looked closer at it, I noticed some interesting things. The picture below is a screenshot of the same area with the alleged nuclear reactor in the orange circle. Notice further up the three dots in the orange rectangle.
These three dots are photographs tagged onto Google Earth by a tourist who had driven to that area, by the name of Kevin Rouze. They are of the Halabiyya city wall and are not far at all from the alleged site. So about 7-10km maximum from this allegedly top secret "nuclear facility" is a tourist snapping photos and driving around, there is also a busy bridge and a main road it seems.