The materials and energy of the radiation were not destroyed though, since energy cannot truly be destroyed. Instead, the Earth transmuted the material and energy to something that was more habitable to humans and the environment. This change was profound and led to a dramatic change in the human race. Some aspects of the new energy were quite dramatic. In a few places the crust of the Earth collapsed leaving a boiling area of this new energy. In other places the energy slowly leaked out into the atmosphere wreaking amazing changes on the population in that area. The people that were continuously exposed to this energy developed the ability to manipulate the elements. To harness the power of the earth and make it do amazing things.
The world was a vastly different place. Civilization was struggling to survive. The world was struggling to recover from the wanton destruction and people themselves were changing. Some individuals used this opportunity to collect power for themselves. Others took it as a sign from the Earth and started pilgrimages toward the areas where the elemental energy pooled. Some, in an attempt to commune with their new god, flung themselves into the this rolling mass of energy. After no new messiah appeared and none of the leapers reappeared, that practice started to decline.
That is pretty much how the world sits now, nearly twenty years later. There are very few central governments and their influences are in smaller areas. Gone are the wide sweeping countries, held together by a central governmental influence from far away. Now areas were rules by small dictators in something of a warlord like fashion. Unlike what most of the movies set in the future predicted at the end of the 20th century, technology has not declined. It has instead continued on, but it has been limited to groups of people. Many of the think tanks that existed before the devastation continue to thrive, but they do not share a lot of their developments with the rest of society. They exist as a rough anti-thesis to the extremely secularized religious groups that have developed. The major corporations that were left and survived the loss of the main governments joined with the new smaller governments to create the enforcers. A group of individuals designed to control the populace of the world. The new magic users of the world are struggling not only with their place in the world, but also with a human race that isn’t exactly sure they like the changes.