From AP, :
KIEV, Ukraine — Ukrainian security forces seized nearly 375 pounds of a radioactive material seen as a likely ingredient for a “dirty bomb”, authorities said Thursday.
In a joint action, Ukraine’s police and state security agents seized two containers of cesium-137 and arrested three men from the southern city of Simferopol on the Crimean peninsula, police spokesman Yuriy Kondratyev told The Associated Press. An unspecified number of people also were detained throughout Ukraine.
Cesium-137 is considered a likely ingredient for a so-called “dirty bomb,” in which conventional explosives are combined with radioactive material.