The peril of a “dirty bomb” — a primitive radioactive explosion that could be set off by a terrorist group — which has haunted the dreams of counter-terror specialists around the world, has been greatly overestimated, according to Israeli research findings.
Researchers at the Negev Nuclear Research Facility in Dimona concluded the Green Field project in 2014, a series of tests made over four years to determine the actual damage such a device could cause.
Packing radioactive material with conventional explosives, the Israeli scientists simulated “dirty bomb” blasts under varying conditions and arrived at the conclusion that such a device, if in the hands of terrorists, would not pose a significant danger to public safety.
The Green Field project involved 20 detonations of between 250 grams and 25 kilograms of conventional explosives, together with a familiar radioactive substance used for medical imaging known as 99mTc (known also by its trade name, Cardiolite).
High-level radiation was detected at the center of the explosions, though wind dispersal of radiation particles was measured at a low level, the report said. The effect of such a weapon would be mostly psychological, they said.
In one of the tests, an undetonated dirty bomb was left in the equivalent of a public place. A substance was mixed with water in the ventilation system of a two-story building on an army base belonging to the Home Front Command that was meant to simulate a shopping mall. Most of the radiation remained on the building’s air-conditioning filters.
However, if a dirty bomb were to explode in a closed space, it would have to be cordoned off for a long time until the radiation had dissipated.
In the meantime, although the materials for such a bomb are available commercially, no one has ever tried to use such a bomb, the authors of the report said.