This response is from my husband, Barry Setterfield:
In the first place, the model proposed here starts with the earth cold and the relevant minerals in the crust and mantle already are saturated with water, so no further water can be absorbed.
Now the earth was formless and empty, darkness was over the surface of the deep, and the Spirit of God was hovering over the waters.
Genesis 1:2
Geologists now point out that there was a band of radioactive material concentrated about 1700 km beneath the crust, in the mantle, in the original earth. The radioactive material now in the crust appears to have come from this layer by geological processes. With a high speed of light, which has been documented and statistically defended, the rate of radioactive decay was much faster and produced the heat that we have now in the center of the earth. As the minerals in the mantle and crust heated up, the water was driven off, not absorbed. They could not absorb more than they had; they were fully saturated.
The evidence we see today is the presence of olivine, which is serpentine with the water driven out! We also see the minerals in meteorites still hydrated, as the earth's material was originally.
You wrote, "Between the time of Eden, and the flood, all this water you’re suggesting was expelled from the inner earths radioactive engine would have been absorbed into the surrounding rock." Are you suggesting the Bible is wrong when it states "all the springs of the great deep burst forth"?
In addition, the water could not be absorbed into the surrounding rock, for the crust material was already fully hydrated and the material deeper down was precisely where the heating was occurring which was driving out the water. Heat does not cause water to be absorbed into rocks!
You will also notice Genesis 2:5-7, where we are told fountains, or springs, or mists, or streams (depending on your translation) watered the face of the whole earth. Water does not come uphill from the depths unless it is under pressure, and, in this case, increasing pressure.
In other words, the interior heating could not possibly have caused rocks and minerals to absorb water, That was the process by which it was driven out of those materials. That water initiated the Flood and the bursting destroyed the earth that was then and buried it under at least 2.5 km of rock and debris and the carbon rich material -- all of which is found in the precambrian and gives evidence that the Bible is quite right in its narrative of the Flood.
In short, Eden may have been where Israel is today, but it is over 2 miles down.