Wed Oct 26 09:50:28 SAST 2016

SA invention keeps bomb makers at bay

By unknown | May 04, 2007 | COMMENTS [ 0 ]

Joel Avni

Joel Avni

South African scientists are playing a key role in preventing radioactive material scattered around the continent from falling into the hands of terrorists.

Hospitals around Africa have a tawdry history when it comes to storing depleted radioactive materials that reach the end of their useful life for medical treatment.

Though the spent materials, such as cobalt and caesium, are no longer suitable for medical purposes they remain highly radioactive and dangerous.

"Some of these sources might contain as much as 3000Curies of radiation," says Rob Adam, chief executive of the Nuclear Energy Corporation of South Africa (Necsa).

The Chernobyl nuclear reactor that blew up in Ukraine in 1986 is estimated to have spewed out 90million Curies of radioactive material in the explosion.

Contaminated dust and smoke blanketed much of Europe and left an area 30km around the plant a poisoned wasteland.

In Africa used up nuclear medical devices are often left in storerooms and other unguarded sites. But the radioactive materials they contain could be used by terrorists to build "dirty bombs".

All a would-be bomber would need is the radioactive material and a few of sticks of dynamite. Such a low-tech dirty bomb would spread dangerously radioactive material over a wide area.

Because of the uncertainty over the spread of the radiation, a dirty bomb is one of the most dangerous weapons in the terrorist's arsenal.

So in December 2003 Mohamed al-Mughrabi of the International Atomic Energy Agency (IAEA), the world body responsible for supervising nuclear materials, asked South Africa to help allay this threat.

Africa has a bad history of securing dangerous radioactive materials and Necsa has been involved in clearing up less highly radioactive medical waste, such as radium, in 11 countries around the continent for the past seven years.

Scientists at Necsa's nuclear liabilities management division designed a mobile unit that can be shipped around the continent to disassemble devices containing radioactive material and remove the material for safekeeping.

The compact "hot cell" workshop is particularly suitable for African conditions, says Gert Liebenberg, manager of the division. It can be stripped down and shipped anywhere in a standard 20-foot container.

Technicians need only a week to assemble the hot cell and a week to disassemble it. Apart from its robotic arms, the unit is made from low-tech materials and is easy to maintain and transport. Best of all, the shielding used to protect the operators is river sand, which can be sourced wherever the unit is being used.

The laboratory-cum-workshop has 1,5m-thick walls to contain the radioactive materials being stripped from medical devices. These robotic arms allow technicians to handle the material safely from outside.

The medical equipment is disassembled and the capsule of still dangerously radioactive material is removed and sealed in a specially designed stainless steel container called a long-term storage shield.

No one had conceived of such a large mobile workshop to work with such highly radioactive devices.

The design was completed in August 2004 and was evaluated by a team of experts from the US, the UK, Belgium and Sudan.

By 2005 the IAEA had approved the concept and gave South Africa the go-ahead to build the mobile hot cell with funds provided by the US.

Though the completed facility was unveiled only recently, countries in Asia and South America are already interested. The IAEA plans to introduce these mobile workshops around the world to help resolve a global problem with highly radioactive medical wastes in countries that do not have the facilities or expertise to handle them.

The unit will soon be shipped to Tanzania and Sudan to start its mission.

Necsa's Adam estimates that about 50 pieces of medical equipment around the continent need to be disassembled and have their highly radioactive innards taken out and stored safely.


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