Krytrons The Complex Detonators Needed For N-blasts
Sydney Morning Herald
Thursday March 29, 1990
LONDON, Thursday: The sophisticated nuclear triggers known as krytrons are the ultra high-speed electrical switches that start the extremely complex process necessary to achieve a nuclear explosion.
A nuclear warhead resembles a hollow ball of conventional explosives surrounding a plutonium core.
A nuclear blast occurs when the conventional explosives are fired, exerting tremendous pressure inwards on the core, which compresses and goes "critical"
The triggers, similar to advanced switches, fire the detonators with a very high-speed pulse of electrical current in microseconds. These, in turn, set off the conventional explosives.
Timing is critical because the detonators must be fired in precisely the correct sequence so that the right amount of pressure is exerted on the plutonium core.
As a result, the krytrons are crucial for successful detonation and represent sophisticated electronics and engineering beyond the capability of most nations.
Although they may have commercial applications in photocopier machines and laser power supply systems, the krytrons, which sell for less than $US100($A133) a piece, are also used in nuclear weapons programs, and their export is strictly controlled.
The US authorities have thwarted two attempts - one by Israel and one by Pakistan - to smuggle krytrons.
Defence analysts speculated today that Iraq's attempts to acquire nuclear weapon triggers meant it was much closer to building a nuclear missile than widely thought.
It is thought the Iraqis would be most unlikely to try to smuggle in the trigger systems before ensuring they had sufficient material to build a warhead.
It is understood that the 40 krytrons discovered at Heathrow would be enough to arm one or two nuclear bombs, depending on the sophistication of the device.
Because of the need to trigger a very precise explosion and keep the shockwave going in order to achieve a large nuclear blast, a substantial number of krytrons is required.
The more krytrons, the more predictable the blast.
In the latest sophisticated US devices, the number of krytrons required runs into dozens, while more basic designs need far fewer.
Krytrons are the most sophisticated and complicated parts of today's nuclear weapons.
© 1990 Sydney Morning Herald