/ 30 November 2005

Cape power cuts ‘not Koeberg’s fault’

The electricity supply to consumers in the Western Cape was interrupted twice in November — but the Koeberg nuclear power station was not the cause of the supply interruptions, the Department of Public Enterprises said on Wednesday.

The region was without power on both occasions after a reactor unit at Koeberg was shut down as a normal safety precaution, said the department, which is responsible for state-owned electricity utility Eskom.

”On both occasions, Koeberg reacted exactly as it was designed to do to ensure maximum operating safety. While any incident that results in the consumer being inconvenienced in any way is regrettable, these particular incidents can neither be attributed to Koeberg being a nuclear station nor unsafe in its operation.

”In fact, until this series of events, Koeberg was Eskom’s most reliable power station,” the department said.

The last time that a Koeberg unit tripped from the transmission network was in 2003, while the last time that both of Koeberg’s reactors were shut down was in October 2001.

The supply interruption on November 11 resulted from a switch-gear trip during a procedure necessary to return Koeberg’s unit one to service, and occurred outside Koeberg on the transmission grid. The grid disturbance resulting from this switch-gear trip caused the second unit to shut down and the station to go into safe operation mode.

The November 16 supply interruption was caused by a veld fire, a problem that has long plagued electric transmission systems in South Africa.

A runaway fire on a farm in the Wellington area beneath a transmission line caused the line to trip. Once again, unit two tripped and Koeberg went into safe operation mode.

”Not only is Koeberg safe and reliable by comparison with non-nuclear stations, but is also safe when compared with other nuclear stations internationally. Koeberg is currently in the top quartile of performers using the Institute of Nuclear Power Operations [Inpo] index as a benchmark,” the department said.

Inpo is an American organisation of nuclear-plant operators whose mission it is to promote the highest levels of safety and reliability. This means that Koeberg has performed better than more than three-quarters of the United States’s power stations, which are among the best run in the world.

Last year, Koeberg was the runner-up in Electricite de France’s annual nuclear safety awards in the category of nuclear safety.

This is a competition for French-built pressurised water reactors, and includes nuclear plants in France, China and Belgium. Until November’s incidents, Koeberg was this year’s forerunner.

”Unfortunately, as hard as engineers may work to continuously improve system reliability, no electricity system is fool-proof and we will be reminded of this from time to time by incidents not only in our own country, but [also] around the world,” the department said.

The modifications currently being implemented during the refuelling outage and others to be implemented in future will improve its operating safety still further.

Koeberg has been the backbone of power supply to the Western Cape for a generation and, until such time as new base-load generating capacity is built in the Cape, it will continue to be so.

The 2003 blackouts in Europe, Asia and North America highlighted the urgent need for more electricity-generation capacity. Coal is not the answer, given environmental concerns about carbon-dioxide emissions.

The Massachusetts Institute of Technology has forecast a threefold rise in nuclear power globally to one trillion watts by 2050, a move that will reduce carbon-dioxide emissions by about 1,8-billion tonnes annually.

At the end of 2002, there were 441 nuclear power plants operating in 30 countries, representing a total capacity of 359 gigawatts, more than 10 000 reactor-years of operating experience, 16% of global electricity generation and 7% of global primary energy use.

The Swiss in 2003 voted not to scrap nuclear power after the government argued it would be premature to shut down a cheap energy source that met 40% of the country’s power needs. — I-Net Bridge