TEHRAN (Reuters) - Iran said on Wednesday it would start increasing uranium enrichment at some of its nuclear facilities and pumping gas into centrifuges, while Washington said it was a step in the wrong direction and could lead to a nuclear Iran.

What is uranium enrichment, and what does centrifugation mean?

Enrichment
The process of enriching uranium is the cornerstone of converting this ore found in nature either into a material that can be used peacefully in the production of energy within certain criteria and conditions, or into a lethal weapon.

It is noteworthy that the enrichment process is not itself a decisive factor in determining the peaceful or non-peaceful nature of any nuclear program but the proportion of enrichment.

Enrichment is a complex, phased process aimed at increasing the proportion of uranium 235 - the fissile isotope in uranium ore, symbolized by the Latin letter "U" - to be suitable for use as a nuclear fuel or for making an explosive compact core in nuclear weapons.

Enrichment is essential because uranium is found in nature in a variety of ways, but one form of this ore 235, which can be used to produce electricity or for military purposes.

In physics, this type of uranium is referred to as "U 235" relative to the number of its atomic mass, which is found only in approximately 0.7% of the ore extracted, while the common isotope in uranium ore is known as "U238", and its atomic mass is larger some Thing.

For energy and electricity purposes, the concentration of uranium 235 should be increased to between 3 and 5 percent, while its concentration must be increased to levels above 80 percent, known as the ideal purity for a nuclear weapon.

Enrichment techniques
The first step in enrichment technology is to convert uranium, known as "yellowcake," into a gas called uranium hexafluoride (UF6), meaning that the enrichment process begins only after uranium ore is converted from its solid state to its gaseous state.

When uranium is pumped in its gaseous form through an influence barrier, the lightest uranium 235 traverses the barrier more quickly than uranium atom 238, as is the case with small grains of sand passing through the sieve openings, or any strainer or tool to separate fine fine grains.

This separation process has to be repeated more than 1,400 times to obtain uranium 235 at a concentration of 3 to 5 percent of UF6.

The Iranian Atomic Energy Agency confirmed that it has sufficient stockpile of enriched uranium by 20%, and that it is able to enrich at a high rate if it runs out of stockpile.

Centrifuges
As in the separation process, centrifuges exploit the slight difference between the isotopes of uranium 235 and 238, where uranium, in its gaseous form, is pumped into a cylinder at higher velocities.

In this case, the heavier atoms - uranium 238 - are pushed outward and accumulate on the cylinder wall, while the lighter atoms - uranium-235 - gather around the center, then the enriched uranium-235 is collected and the process is repeated several times to increase its concentration.

The manufacture of 20 kilograms of enriched uranium to make a single nuclear warhead primitive explosive capacity requires about 1500 centrifuges and a continuous process without interruption for several months.

The Iranian president announced that his country has 1,044 centrifuges in the Verdou reactor, and said he would ask the IAEA to start pumping gas into these devices.

For its part, the State Department stressed that Iran's persistence in uranium enrichment activities is a big step in the wrong direction, and that it will only increase its political and economic isolation.

It considered that the recent measures implemented by Iran could ultimately help it to acquire a nuclear weapon if it so decides.