NICOSIA, Aug 26: Iranian President Mahmoud Ahmadinejad inaugurated a heavy water production plant on Saturday despite a call from the United Nations to suspend its controversial nuclear activities.

The United Nations Security Council told Iran to suspend such sensitive work or face possible sanctions because heavy water reactors can be used to produce plutonium, which is the fissile core of most modern nuclear weapons.

Heavy water or deuterium oxide (D20) is a natural form of water (H20) used to lower the energy of neutrons in a reactor.

It is about 10 per cent heavier than normal water and occurs naturally in minute quantities, about one part heavy water per 7,000 parts regular water.

In heavy water, the two hydrogen atoms (H2) have been replaced by deuterium (D2), a heavy isotope of hydrogen, the International Atomic Energy Agency (IAEA) explains on its website.

The nucleus of deuterium atoms contain one proton and one neutron, as opposed to just one proton in the case of hydrogen atoms.

Heavy water is thus able to slow, or moderate, neutrons from fissioning uranium, permitting a sustained chain-reaction in reactors using natural uranium as fuel.

It is classified as “sensitive material” because a nation possessing heavy water can produce plutonium directly from natural uranium, thus bypassing the need for uranium enrichment.

The production of industrial quantities of heavy water has always been monitored and trade in the material is controlled.

Iran says it only wants civil nuclear power and has the right to master the required technology but western countries, led by the United States, believe that its civilian programme hides a covert military plan to build an atomic bomb.

Israel is believed to be the only Middle Eastern country to possess a nuclear arsenal, estimated at roughly 200 nuclear warheads, although the Jewish state has never confirmed nor denied it has such weapons.

A suspected nuclear site at Dimona, Israel, was reportedly developed using a heavy water process.—AFP