Activists: Chernobyl Radiation Lingers (AP) AP - The signs say "KEEP OUT" and warn of radiation contamination, but the mushroom-pickers trudge right past them carrying their pails. Eighteen years after the reactor at Chernobyl in neighboring Ukraine exploded, spewing a cloud of radiation that blew north and contaminated 22 percent of this ex-Soviet republic, activists warn of a new threat facing Belarusians: the longing to return to normal life.