Belz...
Fiend God
It would if you had an inkling about what was going on.
Some of the products of Uranium based Fission are gases, such as Xenon-137 and Krypton-90. These can escape the fuel rods and be in the atmosphere of the reactor. When the pressure gets to much and they vent it, these gases get out with the steam and cause spikes that force evacuations. They also have very short halflifes, so decay quickly via Beta emmision, Xenon into Caesium-137 and the Krypton into Strongtium-90. Both of these are Beta emitters as well. Further you have the likes of these gases and Iodine-131 from the spend fuel pool rods as they have reacted due to the lower water levels, this further adds to the contamination about the area.
The levels of radioactivity measured at the boundry of the plant are from the contaminants in the area where the reading is being taken, in other words, most of what is measured there tells us approximately how much combined Xe-137, Kr-90, Cs-137, Sr-90, and I-131 is in the air and on the ground within a dozen or so metres of that area. It's not messuring gamma radiation being fired out of the plant 500m away.
I suppose this answers my question, then ?