Three recent power cuts in the Western Cape all occurred because reactors at the Koeberg power station, Africa's only nuclear power generator, had to be shut down to avert danger.
Though Koeberg was not directly at fault, the shutdowns have raised the debate about nuclear policy and future nuclear power plans in SA.
Eskom is adamant that operations at the Koeberg are among the safest, but residents in and around Cape Town have expressed concern about the reliability of operations at the plant and, more broadly, Eskom's ability to cope with the demand for electricity.
An electrical switching fault, a fire under the transmission lines near Wellington and an imbalance in a standby safety system at Koeberg caused the cuts. Each time, a unit at Koeberg had to be shut down.
Energy expert Andrew Kenny says they were minor incidents. "This is its safety mechanism. It is designed to do this. A healthy electricity grid should be able to cope with one less generating unit. Other units on the grid are then required to work a bit harder," he says.
But SA's grid is overloaded, he says. Power stations are running at capacity and transmission lines are at their limits. "A small knock to the grid will cause it to fall over," he says.
Kenny says a healthy electricity supply system has a reserve of about 15%, which allows for maintenance shutdowns and problems. SA has a reserve of 8%, based on a total electricity generating capacity of 36 500 MW and a peak load of 34 200 MW last year and 33 600 MW this year.
Spokesman Fani Zulu says Eskom's five-year plan to increase output will match the demands of the economy (see Business December 9).
But Kenny says that along with SA's traditional coal-based energy, and hydropower imported from the Cahora Bassa dam in Mozambique, nuclear power is an important part of SA's energy future.
Koeberg began operating in 1984, and supplies about 5% of SA's total electricity needs. Located 30 km outside Cape Town, the plant uses a pressurised water reactor design. It uses water from the cold Atlantic Ocean for cooling. Its two units provide 900 MW each.
Though Koeberg works well, says Kenny, it has high capital costs, and SA needs new technology, like the Pebble Bed Modular Reactor (PBMR). Plans are afoot for the construction of a test plant for a PBMR at Koeberg.
Earlier this year, Earthlife Africa, an antinuclear group, took the department of environment & tourism to court after it approved the original environmental impact assessment (EIA) for a demonstration plant. The Cape high court ruled the process was flawed and rescinded the approval. Last month it ordered Eskom to restart the EIA from scratch.
Eskom had applied to the department to increase the output of the test plant from 302 MW to 400 MW.
Eskom research & strategy chief Steve Lennon says nuclear power is definitely part of its future energy mix, as it embarks on its R200bn 20-year expansion plan. Depending on the results of the demonstration unit, he expects that a fleet of about 20 PBMR plants could provide up to 4 000 MW of capacity by 2015.
SA's Nuclear Energy Act of 1997 provides for the creation of the SA Nuclear Energy Corp and regulates the acquisition and possession of nuclear fuel as well as compliance with the nuclear nonproliferation treaty.
In February 2004, an SA government delegation consisting of Eskom representatives and officials from the departments of trade & industry and minerals & energy held talks in Paris with French company Areva on the company's participation in the construction of the PBMR. Areva is a possible international investor.
In June 2004, the cabinet endorsed a plan to develop the PBMR over five to 10 years. The idea, said then minerals & energy minister Phumzile Mlambo-Ngcuka, was to grow a "critical research and skills base to support the PBMR programme and a sustainable nuclear industry in SA".
Nuclear affairs chief director Tseliso Maqubela says the department will ensure there is a regulatory framework to facilitate evaluation of the PBMR.
"One of government's objectives is to ensure security of energy supply through diversification of primary energy sources. The pursuit of nuclear energy options is in keeping with that objective. The PBMR has the potential to be a major contributor to meeting SA's electricity needs and indeed the needs of other countries," Maqubela says.
A radioactive waste management policy - a precondition for the PBMR - was approved by cabinet this month.
PBMR technology is still in the research phase, and if a demonstration reactor is successful, commercial modules will be available only from 2013.
Earthlife says exposure to chemicals at nuclear stations has negative health effects on workers and those living in the vicinity of plants. The group is conducting medical tests on former employees of Pelindaba, the SA Nuclear Energy Corp site outside Pretoria. Earlier this year, Earthlife claimed radioactive ores were buried at Pelindaba.
"The disposal of waste is also a big concern. Waste generated from nuclear power plants can affect the land is it buried in," says Mashile Phalane, coordinator of the Earthlife campaign "Nuclear energy costs the Earth".
Earthlife also questions the financial viability of building the PBMR. Construction, licensing and engineering fees, maintenance, waste disposal and plant decommissioning are all part of the project cost, which the PBMR Company estimates will be R14,5bn. But an international expert said in a report in August that the cost could reach 25bn.
Last week, the PBMR Company awarded two contracts worth R100m to Japan's Mitsubishi Heavy Industries for the manufacturing of the core barrel assembly and the supply of components for the demonstration plant.
