Story highlights

The Tehran Research Reactor produces radiation used in medicine

The facility falls outside the scope of Iran's nuclear agreement

Foreign and Iranian journalists were allowed to tour the reactor

Tehran, Iran CNN  — 

In the middle of busy Tehran, nuclear reactions continue apace.

But this radiation is perfectly legal – far removed, the government hopes, from an era of secretive nuclear development that isolated Iran from most of the world.

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In an era of openness in Iran – at least relative to years past – the government is showing off its Tehran Research Reactor for the world to see.

Foreign and Iranian journalists were escorted to the reactor on Wednesday morning. Phones and cameras were not allowed inside.

Men in camouflage uniforms with pistols at their waists stood around the complex and accompanied the journalists on their tour, but the mood was relaxed. Other than a somewhat unnerving moment in a decades-old airlock chamber leading to the reactor, it was more high school science tour than sensitive government installation.

Outfitted in white lab coats and blue protective foot coverings, we were paraded around the reactor, which was supplied by an American company in the 1960s.

The building seems hardly changed from the day it was completed.

Its signs are in English and a heavy-duty crane is stamped “Wien,” made in the Austrian capital, Vienna.

Overhead, the ubiquitous portraits of two supreme leaders hang – the founding father, Ayatollah Ruhollah Khomeini, and the current leader, Seyyed Ali Khamenei.

A vaguely chemical smell lingers in the air.

At the building’s center, a small cooling pond is lined, deceptively, with white tiles that wouldn’t be out of place at a swimming pool. Below 7.2 meters (24 feet) of bright blue water lie rectangular aluminum rods filled with uranium-235, enriched to 20%, far below the threshold for nuclear weapons.

“All Iranian-made,” says a young tour guide who goes only by Saeed.

Every week, he says, a group of students comes through; every month, inspectors from the International Atomic Energy Agency inspect the operation.

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A hard-won agreement with world powers, implemented last month, significantly limits Iran’s nuclear activities. But this reactor, used for research and to make radioactive pharmaceuticals, uses only low-enriched uranium and so falls outside the scope of the agreement.

It’s just a “baby” reactor, Saeed says. At 5 megawatts, it produces no electricity, only radiation to make irradiated isotopes for use in medicine. (By comparison, he says, the reactor at Bushehr – now turned off – was 1,000 megawatts.)

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The reactor, owned by the government, works hand in hand with the privately owned Pars Isotope Company. Through a series of vacuum tubes reminiscent of a bygone era, scientists send the isotopes, exposed to the uranium’s radiation, to lab technicians who ready them for hospitals not only in Iran, but in India, Pakistan and Lebanon.