I know I am a bad person for reviving an old post, but I found this challenge yesterday and really had some fun with it. I looked through the thread to see if this was already mentioned and I don't believe it was. If you are up for mods you could get the Too much TNT mod which has a Nuclear TNT. It creates a huge crater that is covered in green radioactive waste that damages you. I set the bomb off then went underground and built my shelter. I only did this way because I didn't know how far down the bomb would go.(it went down about twelve blocks)
Here is a pic from ground zero.
Here is an Arial view of it
This adds a very real aspect to it,and makes it that much harder as the terrain will kill you as well as potential food sources. This will make traveling at any time dangerous. The mod pack also gives you the radiation tiles so you can place them with out the bomb. They make travel nearly impossible if you build your structure at ground zero. You will have to tunnel out around it to find resources so you really have to survive with what you have in your chest.