TEHRAN Iran's first nuclear power station will be loaded with fuel on Saturday, a showcase for Tehran's claim that its atomic ambitions are purely peaceful.
Experts say firing up the $1-billion Bushehr plant will not take Iran any closer to building a nuclear bomb as Russia will supply the enriched uranium for the reactor and take away spent fuel rods which could be used to make weapons-grade plutonium.
Iran insists it does not want nuclear weapons anyway.
After decades of delays, the event is a milestone in Iran's path to harness technology which it says will reduce consumption of its abundant fossil fuels, allowing it to export more oil and gas and to prepare for the day when the minerals riches dry up.
"It is a big day. Iran has been waiting for it for years. Bushehr has seen the start up postponed so many times that Iranians will breath a sigh of relief," said Mark Fitzpatrick of London's International Institute for Strategic Studies.
Iran will claim victory over the United States which has tried to block a nuclear program it sees as highly suspect.
Western nations question why Iran wants to enrich uranium itself when, as Bushehr shows, it does not need it for power stations. Tehran's refusal to cease enrichment has resulted in a raft of new United Nations sanctions and tougher unilateral measures by the United States, the European Union and elsewhere.
"The inauguration of the plant will be a thorn in the side of ill-wishers," said Ali Akbar Salehi, the head of Iran's Atomic Energy Organization.
Diplomats say the Bushehr plant, monitored by the International Atomic Energy Agency, the United Nations nuclear watchdog, poses little proliferation risk and has no link with Iran's secretive uranium enrichment program, seen as the main "weaponization" threat, at other installations.
But that has not prevented hawks in Washington flagging Saturday, when Russian and Iranian specialists begin loading fuel rods into the reactor, as a threshold.
"If Israel's going to do anything against Bushehr it has to move in the next eight days. If they don't, then as I say something Saddam Hussein wanted but couldn't get, a functioning nuclear reactor ... the Iranians, sworn enemies of Israel, will have," the former U.S. ambassador to the United Nations, John Bolton, told Fox News television last week.
Israel bombed a site where the then Iraqi leader was building a nuclear reactor in 1981 and has not ruled out taking similar pre-emptive military action against Iran which it believes could try to annihilate the Jewish state.
Ali Ansari, an Iran expert at Scotland's St Andrews university said Tehran and its foes were likely to exaggerate the importance of the start-up of Bushehr.
"It will obviously have a very theatrical opening but the delays have meant that the power plant is a very old model and the contribution to the national grid is very small. It is also, as far as I understand, a light water reactor which cannot produce anything for a bomb," he said.
"If I was in the U.S. (administration) I would congratulate them on the opening, to reinforce the view that you have nothing against well monitored civil nuclear power."
As a signatory of the Nuclear Non-Proliferation Treaty (NPT), Iran has a right to peaceful nuclear power, something sought by several other oil-rich nations in the Gulf.
But many countries question whether Iran's motives are purely peaceful, pointing out that Tehran failed to declare its enrichment activities for many years and then accusing the Islamic Republic of not being fully transparent with U.N. inspectors after they were exposed.
Russia, which backed the U.N. sanctions passed in June, has said the checks in place at Bushehr make it an "anchor that keeps Iran in the non-proliferation regime."
Russia agreed in 1995 to build the Bushehr plant on the site of a project begun in the 1970s by German company Siemens, but the project was delayed amid delicate diplomacy with Tehran and the West. Iranian politicians have accused Moscow of delaying it in an effort to influence Iran.
Russia's status as an exporter of nuclear technology might be increasingly valuable as developing countries seek nuclear power as an alternative to fossil fuels.
But that is unlikely to include helping Iran build the 20 nuclear power plants it says it wants, as international sanctions are likely to stifle any future deals, according to non-proliferation analyst Fitzpatrick.
"No country is going to sell it to them ... Russia was exempted from sanctions and export controls because Bushehr was grandfathered. I believe there would be strong pressure on Russia not to build another one."
(Additional reporting by Denis Dyomkin and Alexei Anishchuk in Moscow and Fredrik Dahl in Vienna; Editing by Jon Hemming)