Iranian and Russian nuclear technicians made final preparations to start up Iran's first reactor on Saturday after years of delays, an operation that will mark a milestone in what Tehran considers its right to produce nuclear energy.
Nationwide celebrations are planned for the fuel loading at the Bushehr facility in southern Iran, while Russia pledges to safeguard the plant and prevent spent nuclear fuel from being shifted to a possible weapons program.
"The startup operations will be a big success for Iran," conservative lawmaker Javad Karimi said in Tehran. "It also shows Iran's resolve and capability in pursuing its nuclear activities."
The West has not sought to block the reactor startup as part of its confrontations over Iran's nuclear agenda, a clash that has resulted in repeated rounds of U.N. sanctions against Tehran. Washington and other nations do not specifically object to Tehran's ability to build peaceful reactors that are under international scrutiny.
However, it is seen by hard-liners as defiance of U.N. Security Council sanctions that seek to slow Iran's nuclear advances -- which Tehran's foes worry could eventually push toward atomic weapons.
What concerns America and others -- including Russia -- is Iran's refusal to halt uranium enrichment, a process that can be used to make fuel for nuclear arms.
Russia now must follow through with its agreements, signed by Iran, to remove all spent uranium fuel from the plant and ship it back to Russia for reprocessing. That is supposed to make it impossible for Iran to shift the fuel to a facility where it could be enriched further to weapons-grade levels.
The uranium fuel used at Bushehr is well below the more than 90 percent enrichment needed for a nuclear warhead. Iran is already producing its own uranium enriched to the Bushehr level -- about 3.5 percent. It also has started a pilot program of enriching uranium to 20 percent, which officials say is needed for a medical research reactor.
President Barack Obama's top adviser on nuclear issues, Gary Samore, told The New York Times that he thinks it would take Iran "roughly a year" to turn low-enriched uranium into weapons-grade material. The assessment was reportedly shared with Israel and could ease concerns over the possibility of an imminent Israeli military strike against Iranian nuclear facilities.
Iran's envoy to the U.N. nuclear watchdog, Ali Asghar Soltanieh, said Thursday that any military attack against an operational nuclear power plant would be a direct violation of the U.N. charter. It also would likely provoke international outrage by possibly unleashing dangerous radiation.
Iran has repeatedly denied it is seeking to build atomic weapons and says it has a right to produce its own fuel for several nuclear power plants it plans to build.
The nuclear reactor was a goal launched by the U.S.-backed shah in the 1970s and is now a symbol of the Islamic state's nuclear prowess.
Iranian officials say nationwide celebrations will begin once the fuel loading begins Saturday at the 1,000-megawatt, light-water reactor. Iran says it plans to build other reactors and says designs for a second rector in southwestern Iran are taking shape.
Of greater concern to the West, however, are Iran's stated plans to build 10 new uranium enrichment sites inside protected mountain strongholds. Iran said recently it will begin construction on the first one in March in defiance of the U.N. sanctions.
Russia -- which began work on the reactor in 1995 -- has backed the U.N.'s latest economic squeeze on Iran. But Russian officials argue that starting up the long-delayed Bushehr reactor would require Iran to deepen cooperation with U.N. nuclear inspectors and possibly lead Iran to resume talks over its uranium enrichment program.
Yet Iran has not slowed its push for military advances. Defense Minister Ahmad Vahidi said Friday forces have test-fired a new liquid-fueled missile with advanced guidance systems for ground targets.
Vahidi gave no other details of the new Qiam-1 missile during a nationally broadcast address ahead of Friday prayers at Tehran University. But it could raise Western fears about another advance in Iran's missile arsenal, which already can target Israel and other parts of the region.
The fuel-loading operation is expected to take at least a week at Bushehr, about 745 miles (1,200 kilometers) south of Tehran. It will take more than two months before it begins generating electricity.
Inspectors from the U.N. nuclear watchdog agency, the International Atomic Energy Agency, are expected to monitor the transfer of fuel from a storage site to the reactor, according to Vice President Ali Akbar Salehi, who is also the head of Atomic Energy Organization of Iran.
The process ends years of foot dragging by Russia. Completion of the $1 billion project has been delayed several times. Iranian officials say operation of the plant is already more than a decade behind schedule.
On Friday, security was tight at the Bushehr site. Authorities only allowed cameramen and photographers to shoot from the gate of the sprawling complex on the shores of the Gulf.
Once fuel is loaded into the reactor, the Bushehr facility will be recognized as a nuclear plant under international terms.
Hamid Reza Taraqi, another hard-line leader, claimed the launch will boost Iran's international standing and "will show the failure of all sanctions" against Iran.
The Bushehr plant overlooks the Persian Gulf and is visible from several miles (kilometers) away with its cream-colored dome dominating the green landscape. Soldiers maintain a 24-hour watch on roads leading up to the plant, manning anti-aircraft guns and supported by numerous radar stations.
There are several housing facilities for employees inside the complex plus a separate large compound housing the families of Russian experts and technicians.
Russians began shipping fuel for the plant in 2007 and carried out a test-run of the plant in February 2009.
Russia has walked a fine line on Iran for years. It is one of the six powers leading international efforts to ensure Iran does not develop an atomic bomb. It has backed U.N. sanctions, but strongly criticized the U.S. and the European Union for following up with separate, stronger sanctions.
The Bushehr project dates backs to 1974, when Iran's U.S.-backed Shah Mohammed Reza Pahlavi contracted with the German company Siemens to build the reactor. The company withdrew from the project after the 1979 Islamic Revolution toppled the shah.
The partially finished plant later sustained damages after it was bombed by Iraq during its 1980-88 war against Iran.
Before making the Russian deal to complete Bushehr, Iran signed pacts with Argentina, Spain and other countries only to see them canceled under U.S. pressure.