Johannesburg — ESKOM Enterprises has successfully tested and started up a key element of its mininuclear pebble bed project, which it says is a world first.

Potential international and local investors have been keenly interested in the ability of Eskom Enterprises to finalise the test rig, called a closed-cycle, multishaft gas turbine.

The company is optimistic that the move will help it draw in new investors after having lost US group Exelon earlier this year.

David Nicholls, CEO of the company which is developing the pebble bed modular reactor, said talks were being held with a number of foreign companies that have expressed interest in the technology.

"The (test) will take the process forward considerably as it will help answer questions that investors have on the technical side," he said.

Eskom has been working on the pebble-bed modular reactor since 1993 as part of its quest to find alternative sources of power.

The aim is to build a 125megawatt demonstration reactor at Koeberg near Cape Town, where Africa's only nuclear power plant is located.

The concept revolves around building small reactors, with the commercial reactors being sized to produce about 165 megawatts.

A number of questions about the reactors were raised by an international task team, which studied the experimental technology last year. The team called for clarity on several issues, including financial, economic feasibility and the technical design of the scheme.

Gordon Sibiya, chairman of the team, said at the time that he believed it was necessary for the team to study the pebble bed concept so that government could get a feel of how much work still had to be done. If not, there would have been considerable confusion about the way forward, he said.

Eskom Enterprises has since done additional work on the pilot project and the business case.

The biggest issue facing Eskom Enterprises is, however, its ability to bring in another big international investor.

Prior to pulling out, Exelon had plans to buy 40 of the reactors if the project got the goahead from the SA government.

Exelon said at the time that its decision to withdraw followed a review of its investments.

The group had decided to concentrate on its core business of generation, transmission and distribution, with nuclear energy no longer a focus.

Other investors in the project, notably the UK's British Nuclear Fuels, which has 22,5%, and the Industrial Development Corporation, with 25%, have remained part of the scheme. Eskom, which has a 30% stake and has been the driving force behind it, has also pledged its support.

In terms of this week's test, Nicholls said the main objective was to prove the microturbine model could be sustained and controlled, which was achieved.

The model was fundamental to the development of the next generation of high-temperature, gas cooled reactors in the world.

Gideon Greyvenstein, dean of the faculty of engineering at Potchefstroom University, said the successful demonstration proved that the current configuration of the reactor's power conversion unit was stable and controllable. "We are proud of the world-first achievement, especially as it was funded and managed between industry, academia and the government."