In a statement, state-owned Eskom said that Unit 4 of the Medupi plant, which was on a short-term outage since August 6, experienced an explosion at approximately 22:50 local time which caused extensive damage to the generator.
Eskom said the incident occurred during the activity to displace hydrogen with carbon dioxide and air respectively, for the purposes of finding an external leak. Following the power station preliminary investigation, Eskom said it appears that while performing this activity, air was introduced into the generator at a point where hydrogen was still present in the generator at sufficient quantities to create an explosive mixture, which ignited and resulted in the explosion. It also appears that there was a deviation from the procedure for carrying out this activity.
As such Eskom has undertaken to place those employees who were responsible to manage and execute this work under precautionary suspension pending the conclusion of the Major Event Investigation. Further investigations are also underway into the cause of the incident and Eskom said it would provide updates on any developments, as well as to what extent the incident would impact the national electricity grid.
An energy expert from South Africa, Chris Yelland, tweeted photos of the damage at the Medupi plant and said the ends of the generator in Unit 4 had been blown off and destroyed the generator which would need to be replaced.
Eskom announced the completion of the Medupi coal plant on August 2, saying that the last of the power station’s six generation units had attained commercial operation status. The company said the milestone marked the completion of all building activities on the 4,764MW project, which commenced in May 2007, and that the planned operational life of the station is 50 years.
The Medupi Power Station uses direct dry-cooling systems due to the water scarcity in the nearby area and is the fourth largest coal-fired plant and the largest dry-cooled power station in the world, Eskom says. The power plant incorporates super critical technology, which is able to operate at higher temperatures than Eskom’s earlier generation of boilers and turbines, the company added. The capital cost of the project is R122 billion (£5.9bn) so far, and Eskom expects to spend in total under R135 billion (£6.6bn) on completion of balance of plant.
First pictures of the damage caused by the explosion at #Eskom #Medupi Unit 4 last night: pic.twitter.com/smEVoVMAAn
— Chris Yelland (@chrisyelland) August 9, 2021