Iran, Russia blame pump flaw for atom fuel removal

VIENNA (Reuters) - Iran is believed to have told the U.N. atomic watchdog a broken pump is forcing it to remove fuel from its first nuclear power reactor, a new setback for the $1 billion project, experts familiar with the issue said on Monday.

They said it was a potentially significant problem likely to cause further delays for the Russian-built Bushehr plant, which has yet to start injecting power into Iran's national grid. Russia backed up the claim that a cooling pump had broken.

Iran has said Bushehr, first in a planned network of nuclear power plants, will start producing electricity early this year.

It says the plant is proof of the peaceful nature of its nuclear program and that its uranium enrichment work is only meant to produce reactor fuel, rejecting Western accusations the Islamic Republic may be seeking to develop atomic bombs.

Iranian Foreign Minister Ali Akbar Salehi said in Geneva on Monday: "Safety for us and reliability is more important than the start-up of a reactor at an earlier time."

He was speaking after talks with his EU counterpart which he said he hoped would lead to further talks with world powers on Iran's disputed nuclear program.

The International Atomic Energy Agency (IAEA) said in a report obtained by Reuters on Friday that Iran had told it that fuel assemblies would be removed from the core of the Bushehr reactor, just a few months after they were loaded.

The confidential IAEA document did not give a reason for the unusual action, which is expected to take place soon.

"DAMAGED ELEMENTS"

Russia's state-run nuclear energy agency, Rosatom, said in a statement: "Internal elements belonging to one of the four cooling pumps were found damaged." It said the cause of failure was a worn-out node and that checks on the other three pumps were being carried out.

Small pieces of metal about 3 mm-thick, or about one-eighth of an inch, had entered the cooling system, the agency said.

They would be rinsed out when the reactor vessel was cleaned. "After that fuel will be re-loaded into the reactor unit," the statement added, saying the pumps dated from the 1970s.

One independent expert said if not fixed, the problem could ultimately have led to a small radioactive leakage into the reactor's cooling water.

"They are probably very happy it happened before it went critical (the plant starting to operate) because now they can inspect the fuel a lot more easily," the expert, who declined to be named due to the sensitivity of the issue, told Reuters.

Russia's nuclear agency said that since the plant was not in operation, no additional equipment nor specialists were required.

Bushehr was begun by Germany's Siemens in the 1970s, before Iran's Islamic revolution, and has been dogged by delays. Fuel was loaded into the reactor four months ago but a January deadline for it to start producing electricity was missed.

Further woes could be an embarrassment not only to Iranian politicians who have made Bushehr the showpiece of Tehran's nuclear ambitions, but also for Russia, which would like to export more of its atomic know-how to emerging economies.

Mark Hibbs, a senior associate in the Nuclear Policy Program of the Carnegie Endowment for International Peace, said that if it was a broken pump that was the problem, small bits of metal in the cooling water could damage the fuel rods.

"If that happens, radioactive gases can escape from the fuel and into the coolant," Hibbs said. "There has to be a cause analysis there to find out why the equipment failed."

Iran's nuclear envoy Ali Asghar Soltanieh told the ISNA news agency Russian engineers who built the plant on Iran's Gulf coast had advised that the fuel be unloaded for tests. The plant's head said it was being removed for safety reasons.

Ian Hore-Lacy, communications director at the World Nuclear Association, an industry body, said fuel removal was unusual but it may happen during the run-up to starting the reactor.

"Fuel unloading, removal and replacement of core internals, checking, full inspection of fuel elements, and then re-loading could take about three weeks," he said in an email to Reuters.

Experts say that firing up the Bushehr plant would not take Iran any closer to building a nuclear bomb since Russia will supply the enriched uranium for the reactor and take away spent fuel that could be used to make weapons-grade plutonium.

(Additional reporting by Amie Ferris-Rotman in Moscow; editing by Mark Trevelyan)