It was a fission device with a nominal yield of 1.5 kt.

The M-388 round used a version of the W54 warhead, a very small sub-kiloton fission device.

There, the scientists decided to develop an 'implosion' over the 'gun' type fission device citing economy in the use of fissile material.

In the base of each projectile is a fission device of at least 25 kilotons.

Orange Herald remains the largest fission device ever tested.

The fission devices, on a second test, were reportedly had contained the weapon grade plutonium, producing around at 20kt of nuclear force.

It was a fully functional, full-scale, three-stage hydrogen bomb, tested 32 months after China had made its first fission device.

"Mr. Scott, is that radiation consistent with the detonation of primitive fission devices?"

It was a boosted fission device using plutonium in a "levitated" core design.

"I presume that uranium would be the fuel for fission devices."