New nuclear designs considered

There’s a really good article in Physics World from 1 October that discusses the “next generation”designs for nuclear reactors in a pretty straight forward fashion.

There are several paragraphs devoted to the pebble bed, noting this in relation to the recently ended South African program:

Opinion is divided on the significance of the South African project's termination. Stephen Thomas, an energy-industry expert at the University of Greenwich in London, calls it a "major setback" for the development of very-high-temperature reactors, since, he says, South Africa's efforts appeared to be more advanced than research being carried out elsewhere. However, Bill Stacey, a nuclear engineer at the Georgia Institute of Technology in the US, disagrees with this assessment, adding that South Africa was "just one of many players and not one of the major ones". China, Japan, France and South Korea are also developing technology for high-temperature reactors, some of which is also designed to use pebbles.

For its part, the US is pursuing a variant of the pebble-bed design known as the Next Generation Nuclear Plant (NGNP). Intended to reach temperatures of 750–800 °C, the NGNP will allow for different fuel configurations, with the coated fuel kernels held either in pebbles or hexagonal graphite blocks. According to Harold McFarlane, technical director of GIF and a researcher at the Idaho National Laboratory, the US Congress approved the construction of a prototype NGNP in 2005 but has so far awarded funding only for preliminary research and development.