This is why for certain types of fission reactors that use slow neutrons the uranium fuel is ‘enriched’, meaning that the amount of U-235 in it is increased from the approximate natural 0.7% ...

At 20% enriched, uranium-235 is considered highly enriched uranium, and 90% or higher is known as weapons-grade uranium. The enrichment level depends on the proportion of uranium-235 to uranium-238.

Bombs require its lighter cousin, uranium-235 (U-235), which makes up just 0.7% of natural uranium. Depleted uranium out 1.2 metres tall Gas centrifuge.

The difference between uranium-238 and uranium-235. When we dig uranium out of the ground, 99.27 per cent of it is uranium-238, which has 92 protons and 146 neutrons.

Uranium-235, being lighter, concentrates at the center of the centrifuges. To reach the enrichment level necessary for a nuclear weapon, about 90% of the uranium must be converted into uranium-235.

When natural uranium is put in a chain-reacting pile, its U-235 atoms start splitting and yielding energy, “fission products” and free neutrons.

The thorium may be placed in a reactor fueled with uranium 235. Neutrons produced by the fissioning U-235 are run through a moderator made of graphite or heavy water, thus slowed from 10,000 miles ...