Israel recently carried out a series of tests in the desert in conjunction with a four-year project at the Dimona nuclear reactor to measure the damage and other implications of the detonation of a so-called “dirty” radiological bomb by hostile forces. Such a bomb uses conventional explosives in addition to radioactive material.

Most of the detonations were carried out in the desert and one was performed at a closed facility. The research concluded that high-level radiation was measured at the center of the explosions, with a low level of dispersal of radiation by particles carried by the wind. Sources at the reactor said this doesn’t pose a substantial danger beyond the psychological effect.

An additional concern stems from a radiological explosion in a closed space, which would then require that the area be closed off for an extended period until the effects of the radiation are eliminated.

In 2010, staff from the Dimona nuclear reactor began a series of tests, dubbed the “Green Field” project, designed to measure the consequences of the detonation of a dirty bomb in Israel. The project was concluded in 2014, and its research findings have been presented at scientific gatherings and on nuclear science databases. The researchers explained that the experiments were for defensive purposes and that they were not giving consideration to offensive aspects of the tests.

Public concern over radiological terrorism began after the terrorist attacks in the United States on September 11, 2001 and the threat by representatives of Al-Qaida to use such weaponry against the United States. The radioactive material is available to the medical and industrial sectors, and those who threaten its use as a weapon aim to augment the damage and fear caused by an explosion by adding the threat of radiation to the mix.

No such device has ever been deployed by terrorists, but officials in Israel have prepared for such an eventuality. In 2006, the Health Ministry issued procedures on how to deal with such an event. The website of the Israel Defense Force’s Home Front Command also features an explanation on how to proceed if such an event were to occur.

Above: Explosion of a radioactive device and use of mini-drones to check radiation. Below: Testing of radioactive materials in a mock shopping mall.

In 2013, Defense Minister Moshe Ya’alon issued a warning at a meeting in Canada in which he said the Iranians were interested in advancing the commission of terrorist activity, including use of a dirty bomb, against various Western targets under the nuclear umbrella that they were seeking to acquire, and the world should not show tolerance toward the prospect of a nuclear Iran.

In the course of the experiments, 20 detonations were carried out involving between 250 grams and 25 kilograms of explosives together with the common radioactive substance known as 99mTc, which is used in the health care field for medical imaging. The experiments made use of the reactor’s most innovative technology, including tiny drones used to measure radiation and sensors to measure the force of the blast.

In the course of the project, there was an additional test known as “Red House,” designed to examine another kind of radiological scenario in which a substance would be left in a crowded public space but not exploded. In the experiment, which was conducted together with the Home Front Command, six tests were made using material mixed with water in the ventilation system of a two-story building on a Home Front Command base, simulating a shopping mall. The result of the research was that such an approach is not effective from the terrorists’ perspective, and that most of the radiation remained on the air conditioning filters.