Iran and Russia began to load uranium fuel into Iran’s first nuclear power plant on Saturday in the wake of Tehran’s signal of a possible willingness to compromise on nuclear fuel enrichment, a major concern for the West regarding Iran’s nuclear drive.

Nationwide celebrations are planned for the fuel delivery to the first unit of the 1,000-megawatt Bushehr nuclear power plant in southern Iran as the operation will mark a milestone for a nation that resolve to pursue nuclear program.

The fuel-loading process is expected to take at least a week in Bushehr, about 1,200 km south of Tehran. It will take more than two months before it produces electricity.

Ali Akbar Salehi, head of Iran’s Atomic Energy Organization, said earlier that experts from the International Atomic Energy Agency (IAEA) were expected to oversee the transfer of the fuel, which symbolized the beginning of the physical startup of the unit.

The much-anticipated launch marks an end to decades of delay in building the Beshehr nuclear plant. Its construction was started in the 1970s by a German company but was shelved shortly after the Islamic Revolution in Iran in 1979 as the German side pulled out of the deal.

Russia signed an agreement worth 1 billion U.S. dollars in 1995 to take over the project. Its completion, first scheduled for 1999, was postponed several times by mounting technological and financial challenges and interruptions under pressure from the United States.

Under the agreement between Moscow and Tehran, Russia will take back all spent reactor fuel. Experts of the IAEA will be able to verify that no fuel or waste is diverted.

On the eve of the inauguration of Iran’s first nuclear power plant, President Mahmoud Ahmadinejad indicated that Tehran would stop higher-grade enrichment if the supplies of nuclear fuel supplies for a medical research reactor in Tehran is guaranteed.

In an interview published by Japan’s Yomiuri Shimbun newspaper Friday, Ahmadinejad said “We promise to stop enriching uranium to 20 percent purity if we are ensured fuel supply.”

Iran could halt 20 percent enrichment as part of a deal, he was cited as saying in the interview.

Ahmadinejad’s comments were apparently aimed at reassuring the United States and other Western countries which have long suspected Iran was seeking to develop nuclear weapons. Tehran denied the charge and insisted its nuclear program was peaceful.

What worries the West most is Iran’s refusal to halt uranium enrichment, a process that can be used to make fuel for nuclear weapons.

Adding to the fear is Tehran’s move in February to start enriching uranium to 20 percent purity form 3.5 percent, making it closer to weapons-grade level.

Major powers have offered a fuel exchange deal in exchange for Tehran’s suspension of its move.

Despite Ahmadinejad’s signal, Iran’s nuclear chief Saleh said on Friday Iran will continue enriching uranium to make fuel for the Bushehr plant as Tehran may not always buy it from Moscow.

“The Bushehr plant has a lifespan of 60 years and we plan to use it for 40 years. Suppose we will buy fuel (for Bushehr power plant) for 10 years from the Russians, what are we going to do for the rest 30 to 50 years?” Saleh was quoted by state news agency IRNA as saying.

Russia, which has walked a fine line on Iran for years, has welcomed Ahmadinejad’s offer and called for a meeting as soon as possible to discuss a fuel replacement scheme for the Iranian research reactor.

“We believe that this meeting should be held as soon as possible. The meeting format is a minor matter, while the agenda of the meeting is an essential issue. We should launch this dialogue as quickly as possible,” Russian Deputy Foreign Minister Sergei Ryabkov told Itar-Tass on Friday.

He said Russia would like to invite officials from Turkey and Brazil to participate in this meeting, as these countries signed the Tehran Declaration with Iran on May 17.

Under the deal, Iran agreed to transfer 1,200 kg of low-enriched uranium to Turkey and get within a year 120 kg of 20-percent enriched uranium in return, to keep Tehran’s medical research reactor running.