London, June 26 : Documents released by the British Ministry of Defence suggest that a design flaw in the country's nuclear arsenal could lead to them blowing up "like popcorn" if accidentally dropped.
According to The Telegraph, over 1,700 warheads are affected by the problem known as "popcorning."
A typical Trident nuclear missile contains three to six warheads, and some submarines carry up to 24 missiles, meaning the potential for disaster is huge.
A typical scenario would see the weapon being dropped from a crane while being loaded on or off a submarine.
However, a nuclear-weapons safety manual drawn up by the ministry's internal nuclear-weapons regulator, and declassified last month, argues that this standard single-point design might not be enough to prevent "popcorning".
The manual, seen by the New Scientist, says that warheads should be capable of resisting multiple simultaneous impacts, which "would contribute to the prevention of popcorning and should be a design objective".
It also recommends replacing the highly sensitive explosive that surrounds the warheads' plutonium cores because a single knock may not detonate the core, but could set off the 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.
According to the manual, in the worst-case scenario, people a kilometre away would receive a radiation dose of 100 sieverts - 16 times the lethal dose - although the seriousness of the accident would depend on the pattern of warhead explosions.
The US government's National Nuclear Security Administration said that redesigning warheads to resist multiple impacts and switching to less-sensitive explosives would "enhance" safety, but stressed that current warheads "were, are and continue to be assessed as safe".
A spokesman for the MoD said popcorning was only "a theoretical possibility" and in fact it was "a scenario that is not credible".