Dirty Bomb - programme summary
Responding to an attack - page 4 of 4
The most serious effect of both dirty bomb scenarios is the uncertainty that would be sure to follow. Contamination could be patchy and it may be difficult to assess its extent immediately. The demands to screen people and assess the safety of buildings could be immense in either city.
Preventing panic
Scientists do not have entirely to imagine what the response to a dirty bomb involves. They do have one case study to examine. In 1987, the Brazilian city of Goiânas suffered radiological contamination after a scrap metal merchant stole a small caesium chloride canister and cut it open. Despite its gentle and relatively contained release, the powdery dust drifted across the city. Four people died and around 200 were contaminated.
The understandable reaction of the million-strong population was to seek absolute reassurance about their own health. 10% demanded immediate screening to see whether they had been affected. Hospitals were overwhelmed and residents took to the streets in protest.
"You don't get rid of radiation; you transfer it" |
Dr Michael Levi, Defence expert, Federation of American Scientists |
Cleaning up
The Brazilian experience offers emergency planners information about the decontamination process too. Removing the radioactivity took six months; some buildings had to be demolished as too radioactive to be worth cleaning up.
And 'cleaning up' the radiation is perhaps a misnomer; 'moving it on' would be better. 3,000m³ of rubble, earth and debris was removed, enough to fill a football field waist high. All of it continues to be low level radioactive waste.
Responding to the scenarios
Disaster planners are using the Brazilian example to predict the effect on other cities. In
Horizon's Washington scenario, the likely result is the closedown of parts, perhaps all, of the Metro for decontamination.
In London, as in Goiânas, the cost of making some buildings safe would be too great. This could prompt a decision to demolish or abandon some limited areas. This would depend partly on the speed of response. An immediate clean up can remove around 50% of the radiological contamination but over time the particles combine with the cement in walls and pavements, making the radioactivity much harder to remove.
The greatest uncertainty for contingency planners is the public reaction. What do you say to people once the news first comes out? Would people understand the difference that the size and type of radiological source makes? And would people follow the best advice, namely to stay put? The more information people have, the better equipped they will be to deal with the aftermath of any kind of incident.
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