The six-month long Shanghai World Expo will be a challenge for China's nuclear security forces, although the country has a record as one of the most nuclear secure nations of earth, a leading Chinese arms control expert said Tuesday.

Security forces maintained the safety of nuclear facilities during the 2008 Beijing Olympic Games and Paralympic Games, but the duration of the Expo made it a greater risk, said Teng Jianqun, director of research center for arms control with China Institute of International Studies.

"Many people think that nuclear threat is far from them. However, nuclear technology has been widely used in people's daily lives," Teng said in an interview with Xinhua.

"If terrorists used radioactive dirty bombs to attack major events, there would be panic and even chaos," he said.

Teng cited disgraced Pakistani nuclear scientist Dr. Abdul Qadeer Khan, who confessed in 2004 to selling nuclear secrets, as a warning that some scientists and other parties continued to smuggle, trade and produce nuclear materials for profit and other purposes in a global black market.

The illegal trade and proliferation of nuclear materials would create dangerous possibilities for terrorists to launch attacks, he said.

According to statistics from the International Atomic Energy Agency (IAEA), more than 1,500 cases of smuggling and theft of nuclear materials were reported from 1995 to 2008 around the world.

Security cooperation to prevent terrorists from acquiring nuclear materials was a responsibility shouldered by all countries, no matter what attitude they held toward nuclear issues and whether they possessed nuclear facilities or weapons, Teng said.

China had strived for all-round security measures to safeguard nuclear facilities to maintain regional and world peace, and had established nuclear waste disposal plants throughout the nation, he said.

Each of the mainland's 31 provinces, autonomous regions and municipalities had a special facility to store nuclear waste from power stations, hospitals and other places, Teng said.

A large national-level disposal plant was under strict monitoring and supervision to prevent radiation leaks, he said.