A missing radioactive source of Iridium was narrowed to within a radius of 2 kilometers on Saturday in Nanjing, East China's Jiangsu province, according to city officials.

Local authorities have taken measures to cordon off the area to ensure local residents' safety. No one was found to have been affected by the substance as of Saturday.

Equipment has been sent to search for the Iridium-192, which is about the size of a soybean. Technicians are expected to take more time to retrieve it since it is so small, according to experts.

The Iridium-192 went missing when Tianjin Hongdi Engineering Testing Co was carrying out tests at the Fifth Construction Company of China's oil refiner Sinopec on May 7.

Iridium-192 is a highly radioactive source and potentially harmful – contact can even result in death - if not handled professionally.

Authorities are taking safety precautions and are also keeping people who were in close proximity to the substance under close medical observation.