The Tehran Research Reactor built by the United States

The Tehran Research Reactor is an ageing nuclear facility located in the heart of the Iranian capital.

Built by the United States as a nuclear research facility 40 years ago, it is now at the centre of Iran's claims that it needs nuclear fuel for peaceful purposes only.

The reactor makes radioactive materials for use in hospitals - for example in the treatment of cancer.

Al Jazeera's Alireza Ronaghi was given exclusive access inside the facility.