The purpose of radiological emergency preparedness is to protect people from the effects of radiation exposure after a nuclear accident or bomb. Evacuation is the most effective protective measure. However, if evacuation is impossible or even uncertain, then local fallout shelters and other measures provide the best protection.
Zr) and/or involatiles is less for accident fallout than it is bomb fallout.  A definitive report on Chernobyl is at [http://www.nea.fr/html/rp/chernobyl/allchernobyl.html] - Chapter 2, Table 1 lists the radioisotopes released in the fire. The percentage of the inventory which was released was controlled largely by how volatile the fission product is. Hence a greater proportion of xenon and iodine were released than of cerium and plutonium.
For the longer term response, a review of the methods that can be used to decontaminate an urban environment is provided in the scope report [http://www.icsu-scope.org/downloadpubs/scope50/chapter06.html Behaviour and Decontamination of Artificial Radionuclides in the Urban Environment]. Also see chapter four of the NEA reports [http://citeseer.ist.psu.edu/cache/papers/cs/28102/http:zSzzSzwww.nea.frzSzhtmlzSzrpzSzchernobylzSzchernobyl-1995.pdf/chernobyl-ten-years-on.pdf Chernobyl ten years on] and [http://www.nea.fr/html/rp/reports/2003/nea3508-chernobyl.pdf Chernobyl twenty years on] for details of how farming methods can be changed to reduce the impact of accident fallout.-->