Although the term is usually associated ‘dirty bomb’ to ‘nuclear bomb’they are not the same. The first does not cause a chain reaction or a nuclear explosion, but is a conventional bomb combined with radioactive materials such as plutonium and cesium that are dispersed over a wide area upon detonation. It is a weapon designed not so much to create mass destruction, but to sow fear and instability, coveted by terrorists, and turn the affected area into an area radioactively contaminated for months.
How do you respond to such a threat becoming a reality? In a study published in October in the Chinese Journal of Safety and Environment, Chinese military scientists have simulated a dirty bomb attack to test a new method of containment. The field experiment, conducted by a team from the Joint Logistics Support Force Engineering University and the Rocket Force Research Institute, explores how advanced air systems they could quickly suppress and neutralize radioactive fallout before it spreads.
Aerial suppression technology for radiological attacks
According to the team led by the nuclear emergency expert Lin Yuanyethe new mobile aerial suppression systemsbased on cloud seeding techniques in which chemicals are dispersed into the atmosphere to cause rain, could reduce the devastating impact of a dirty bomb in the future.
According to the South China Morning Post, Yuanye’s team describes how deployable systems in a matter of minutes could be launched after an explosion to disperse special agents that adhere to radioactive aerosols through adsorption, agglutination and coagulation, causing dangerous particles to settle quickly and reducing the spread of radioactive fallout.
A ‘dirty bomb’ with 62 kg of TNT and 1 kg of plutonium
The test simulated a scenario in which 62 kilos of TNT detonated and dispersed one kilo of nuclear weapons-grade plutoniuma highly dangerous material. To reduce meteorological interference, the experiment was conducted on a calm, cloudy afternoon, with winds below 7.2km/h. The explosion took place on a concrete surface to recreate an urban environment, with an ambient temperature of about 25°Ctypical of mild weather conditions.
To track the cloud of radioactive smoke, scientists used non-radioactive tracer dyeswhich behave like radiation, and launched a high altitude balloon next to the explosion to calibrate the height of the cloud of contaminating particles and gases. Besides, laser rangefinders and angle measuring instruments provided accurate spatial data and an image analysis software processed videos and photographs to extract exact information about the movement and expansion of the cloud.
A single dirty bomb could contaminate almost 10 square kilometers
The researchers point out that the combination of real tests and advanced computer models allowed them to obtain highly accurate predictions. Their simulation showed that a single dirty bomb in a city, if left unchecked, could contaminate about 9.8 square kilometers and put tens of thousands of people at risk.
The results identified several exposure zones: one ‘lethal zone’ with radiation levels higher than 1 sievert (100 rem)potentially fatal; a ‘dangerous zone’ with doses between 50 and 100 remwhich would cause serious health effects; and one ‘intervention zone’ which would require immediate evacuation and decontamination.
Two minutes after the detonation
The team proposes using suppression systems launched by rockets to quickly attack the rising radioactive cloud. The rockets would release suppressive agents that cling to radioactive particles, causing them to clump together and fall to the ground more quickly, thus limiting the dispersion of contamination. The research calls this approach ‘high altitude suppression and rapid response’.
Lin’s team adds that, with a suppression efficiency greater than 50%high-risk areas are significantly reduced, and with an efficiency of the 90%they practically disappear. But achieving it requires launch the rockets in less than two minutes after detonationsince any delay allows the cloud to rise and disperse. This requires ultra-rapid detection, early warning and immediate response, key capabilities for both modern military forces and civil defense.
The study suggests establish permanent suppressor rocket bases around sensitive areassuch as large cities, military installations and, especially, coastal nuclear power plants.