dimanche 18 janvier 2009

SA’s first nuclear fuel

Friday, 16 January 2009

South African based nuclear design company, Pebble Bed Modular Reactor (PBMR), has successfully manufactured a new nuclear fuel particle which is a ‘first for Africa’, the company announced on Tuesday.

The new uranium-dioxide coated particles will form the basis of a high temperature reactor fuel, containing 9.6% enriched uranium.

The fuel particles have now been shipped to the Oak Ridge National Laboratory, in the US, where the particles will undergo irradiation testing, PBMR said in a statement.

CEO Jaco Kriek noted that the new fuel is a key driver in PBMR’s backing by the Westinghouse-led consortium, which in 2006 was awarded a contract by the US Department of Energy to consider the PBMR technology.

PBMR consider that "no human error or equipment failure could cause an accident that would harm the public," due to the reactor’s inherent safety designs.

“We have conducted extensive development work and we are satisfied that the coated particles that were produced for testing will provide proof and assurance that the PBMR will perform to its predicted best-in-the-world safety capabilities,” says Kriek.

Kriek said that the successful manufacturing of the coated particles was the culmination of several years of intense development work at PBMR’s laboratories.

The nuclear particle is based on a high-quality German fuel design used in the German AVR research reactor, which was successfully operated for 21 years.

The PBMR fuel differs from conventional nuclear fuel in that the particle coating, which forms a part of the fuel, acts as the fission product barrier. Conventional nuclear fuel uses a metal barrier.

Why this fuel is special
“Normal nuclear fuel (a large core of enriched uranium) gets hotter and hotter, and therefore has to be cooled. This new fuel achieves the same results but without the threat of overheating,” said Dr. Rui Krause, a senior lecturer at the University of Johannesburg.

“These fuel balls act as mini-reactors; with a pebble of enriched uranium coated in a number of materials, mostly different forms of carbon; making a pellet the size of a tennis ball. On its own the heat is minimal, but lots of them would achieve the same result as any other nuclear reactor,” said Dr. Krause.

This fuel is one step in a long line of development aimed at creating a safer form of nuclear reactor. The fuel cells alone have been 9 to 10 years in the making.

“These fuel cells are the result of a good decade or so of science,” said Dr. Krause.

“Globally we need to move away from carbon based fuel, for cleaner alternatives. Wind and solar power would be ideal, but these are inefficient at the moment and costly to install. Globally there is a growing understanding that we need to bit the bullet and use nuclear energy. The world must decide how long this will be.”

“This fuel has made a significant impact, as new plants will face environmental impact problems and civil opposition, and hence governments take risks using nuclear power. This type of fuel development allows them to go for something with the same amount of energy but far safer.”

According to Dr Krause South Africa, through PMBR, will be one of the primary producers of this new fuel, as we hold all the technology that has been developed. “These cells need to be replaced, and are only active for about 6 – 10 years, so new balls constantly need to be added.”

Another benefit to these new fuel cells is the reduction of the threat posed by large amounts of depleted uranium. “From a large core of depleted uranium one can still extract enough undeleted uranium to, lets say, manufacture a nuclear bomb; a proposition that has scared governments in the past. However this new fuel reduces the amount of uranium and removes that threat almost completely,” said Dr. Krause.