Russia-Ukraine war: ‘Dirty bombs’ radiate fear, but impact not on nuclear scale

Vladimir Putin has faced further humiliation on the battlefield in Ukraine. Photo / File

With Vladimir Putin facing further humiliation on the battlefield in Ukraine, there are increasing fears his army may use a “dirty bomb” and blame it on Kyiv.

Yesterday, General Valery Gerasimov, the head of the Russian armed forces, claimed that Ukraine was on the brink of deploying such a weapon in a call with Admiral Sir Tony Radakin, his British opposite number.

Russia’s forces were also said to be ready to work in “radioactive conditions” at a briefing on the issue by Lieutenant-General Igor Kirillov, head of the radiation, chemical and biological defence forces of the Russian armed forces.

The rising drumbeat of propaganda follows calls from General Sergei Shoigu, Russia’s defence minister, to his counterparts in Britain, France, Turkey and the United States claiming a “dirty bomb” strike by Ukraine was coming soon. Western governments rejected the claims, and warned that the world would see through any attempt to blame a dirty bomb attack on Kyiv.

But what is a dirty bomb, and what effect would it have on the war if one were used? First, it is important to understand what dirty bombs are not. Dirty bombs are not small nuclear devices, and will not kill and injure as many people as a nuclear weapon would. Instead, they are primarily tools of terror, in that the psychological impact of any potential use far outweighs the actual effect of the weapon.

The aftermath of a drone attack on buildings in Kyiv, Ukraine. Photo / AP

Designed to scatter radioactive material that has been placed around a conventional explosive such as dynamite, the blast from a dirty bomb is only as powerful as the underlying munition.

An atomic bomb’s explosive power comes from a nuclear chain reaction acting on plutonium or uranium that has been concentrated and highly enriched to about 90 - 95 per cent purity. Nuclear power plants, in contrast, use radioactive isotopes (again, mainly uranium or plutonium) that have been enriched to about a fifth of this figure. The subsequent chain reaction produces heat which can be converted into electricity.

The radioactive material in a dirty bomb does not have to be the extremely pure uranium or plutonium found in atomic weapons, but could come from any of the many radioactive sources used in medicine and industry.

In a dirty bomb explosion, the contaminated material will generally go only as far as the explosion will allow it. Fine particles may travel on the wind, but to have a significant impact, a huge amount of radioactive material would be needed.

Anyone who survived the initial explosion could ingest some radioactive material and require medical treatment. However, few would take in enough to produce radiation sickness.

Depending on the amount of radioactivity present, the area of the blast would have to be decontaminated, abandoned or possibly demolished. Even once sufficiently decontaminated, people could choose to stay away from the area for fear of the long-term health impact.

If a small number of devices laced with radioactive material were to explode in the financial district of a city, regular work could be disrupted for a significant period of time and may never recover fully.

Putin may calculate that a dirty bomb blamed on Kyiv is the excuse he needs to retaliate with a level of ferocity that will please his internal critics and intimidate Ukraine’s Western backers.