YOU might think nuclear weapons have been carefully designed not to go off by accident. Yet more than 1700 of them have design flaws that could conceivably cause multiple warheads to explode one after another 鈥� an effect known as 鈥減opcorning鈥� 鈥� according to a UK Ministry of Defence safety manual.
A typical Trident nuclear missile contains from three to six warheads, and a US submarine might carry up to 24 missiles. Weapons builders aim to prevent accidental explosions of warheads by designing them to be 鈥渟ingle-point safe鈥�. This means that a sudden knock at a single point 鈥� say if it were dropped from a crane while being unloaded from a submarine 鈥� should not detonate the plutonium core.
However, a nuclear-weapons safety manual drawn up by the MoD鈥檚 internal nuclear-weapons regulator argues that this standard single-point design might not be enough to prevent popcorning. The document was declassified last month.
Advertisement
The manual says that warheads should be capable of resisting multiple simultaneous impacts. This 鈥渨ould contribute to the prevention of popcorning and should be a design objective鈥�.
It also recommends replacing the highly sensitive explosive that surrounds the warheads鈥� plutonium cores. A single knock may not detonate the core, but could set off this explosive. Less-sensitive explosives are available, but they are heavier and bulkier than those currently in use, so the warheads would have to be redesigned.
The effects of a popcorning accident would be dire. According to the manual, in the worst-case scenario, people a kilometre away would receive a radiation dose of 100 sieverts 鈥� that鈥檚 16 times the lethal dose. The seriousness of the accident would depend on the pattern of warhead explosions, though.
The US government鈥檚 National Nuclear Security Administration agrees that redesigning warheads to resist multiple impacts and switching to less-sensitive explosives would 鈥渆nhance鈥� safety. But it stresses that the current warheads 鈥渨ere, are and continue to be assessed as safe鈥�. A spokeswoman for the MoD told New 杏吧原创 that although it is 鈥渁 theoretical possibility鈥�, popcorning is 鈥渁 scenario that is not credible鈥�. Any risk is mitigated by the way in which missiles are handled, transported and stored, she says.
Some nuclear-weapons specialists, however, say an accident could still happen. Philip Coyle from the Center for Defense Information, an independent think tank in Washington DC, points out that people sometimes forget safety procedures. He cites the example of last August, when nuclear weapons were unknowingly flown from North Dakota to Louisiana.
Stefan Michalowski, a senior scientist at the OECD in Paris, France, who researched warhead safety at Stanford University in California in the 1990s, is concerned about the risks of an extreme event such as a firefight with direct gunshots. 鈥淭he explosion of a boatload of missiles in a port would be an unimaginable catastrophe,鈥� he says. 鈥淚t鈥檚 a very, very scary thought.鈥�
Weapons Technology 鈥� Keep up with the latest innovations in our cutting edge .
The Nuclear Age 鈥� Learn more about all things nuclear in our explosive .
