What we should fear in 2006
Updated on 22 December 2005
9. Sellafield explosion and fallout
Event
The events at Three Mile Island (Pennsylvania, USA) in 1979 and Chernobyl (Ukraine) in 1986 helped to focus already serious concerns about the inherent safety of nuclear power plants. In both cases, human error contributed to the problem.
At Three Mile Island, the result was a reactor meltdown that (fortunately) failed to breach the containment building. At Chernobyl, the disregarding of safety procedures during tests led to a reactor explosion that breached the containment structure.
In the UK, the Sellafield nuclear facility poses the highest risk of a nuclear incident, largely due to its scale and the huge stockpile of nuclear waste held there. Most vulnerable are the giant tanks of high-level waste that have to be constantly cooled and stirred to prevent a chain reaction.
Sabotage, or an accident - due to prolonged power failure or a plane crash - involving the tanks, or the cooling system that keeps the waste stable, could result in the liquid becoming volatile and cause an explosion.
With more than 200 commercial flights passing within 50 miles of Sellafield every day, a scenario that envisages a crash onto the tanks is not impossible. A more likely scenario, however, is likely to involve human error or the failure of safety systems.
Frequency and probability
The history of the nuclear industry is a short one, extending back barely half a century. Consequently, concepts of frequency and probability have little meaning in the context of a future major incident and radiation release at Sellafield.
Two major nuclear incidents have occurred so far and we will certainly experience others, particularly if the nuclear industry is revived to help combat climate change.
The specific probability of an explosion in the waste tanks at Sellafield and consequent widespread contamination has to be regarded as small but certainly possible.
Impact
The Sellafield storage tanks contain 2,400 kilograms of Caesium-137, the main cause of off-site radiation exposure from the Chernobyl accident. The total amount released from Chernobyl was 27 kilograms, almost 100 times less than the potential release from the Sellafield facility.
Depending on the direction of the wind, cities like Newcastle, Edinburgh and Leeds would be well within fallout range, as would Dublin.
Scaling up the calculated release to the Chernobyl accident suggests that an incident involving the tanks could result in about 750,000 fatal cancers. Depending on wind strength and direction, these will occur in the UK, Ireland, parts of Europe and perhaps further afield.
If all the Caesium-137 is released, the ultimate death toll due to fatal cancers could reach 2.25 million.
Event
Nuclear terrorism is the new bogeyman - used to spread alarm and despondency among civilians following the ending of the cold war.
In the chaotic, post-Soviet world, the raw materials to make a crude, dirty bomb with a yield of a kilotonne (TNT equivalent) or less, are certainly available, as is the expertise and will in some (mutually-exclusive?) circles to build and detonate such a device.
Assuming all three can be brought together, the raw nuclear material smuggled into the UK (assuming it cannot be accessed here), and the bomb constructed and planted undetected, then there may be a threat to the City and to other political and economic targets in the UK.
Frequency and probability
While terrorism is now a way of life for London residents and commuters, and has been so for more than 30 years, there is no precedent for the detonation of a nuclear device in the city.
Worldwide, even the destruction of the World Trade Centre pales into insignificance in comparison to the predicted level of devastation. For the last attempt to create such mayhem in the UK, we probably have to go back to 1605 and the gunpowder plot.
The terms frequency and probability really have no meaning with respect to an unprecedented terrorist attack of this type, given the numerous difficulties that must be overcome to make such an attack successful, however, the probability must be regarded as very low.
Impact
The following effects could be expected to result from the detonation of a primitive nuclear device in the City, with a yield equivalent to 1,000 tonnes of TNT
Within 1 minute people outdoors or near windows inside houses would be killed by thermal radiation up to a distance of 200m from the point of detonation
Within a further minute the blast would kill people up to a distance of 800m, with the initial nuclear radiation killing people up to a distance of 1km
People within 2km would be injured by the heat
Electronic equipment would be affected by an electromagnetic pulse out to about 10km
Depending on winds and meteorological conditions radiological fallout could extend to an area of 400km square
Depending on the timing of the explosion, the immediate death toll could range from a few thousand to hundreds of thousands. The longer-term death toll due to cancers and other illnesses could be higher. Economic losses due to building damage are likely to reach hundreds of billions of pounds.
With decontamination likely to take years, greatest losses, however, will result from long-term business interruption and the shutting down of one of the world's two leading financial centres.
By comparison, the July 7th bombs are estimated to have cost the UK economy between US$4 and US$6 billion, and the 1993 Bishopsgate bomb around US$1.5 billion.
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