Duct failure at Kusile may leave unit 1 down for months

According to a media statement issued by Eskom, a section of the Kusile Unit 1 flue gas duct (the equivalent of a chimney in a household) exiting the sulfur dioxide absorber failed on the horizontal rubber expansion joint as well as the compensator (a bend to direct flue gas up the chimney and allow for thermal expansion of the chimney) whilst the unit was on forced shutdown for flue gas de-sulfuration recirculating pump repairs.

Investigations and assessments are in progress to establish the cause of failure and to ascertain the extent of the damage, as well as the recovery scope of work.

While it is uncertain at this point, it is anticipated the unit may remain offline for a few months and this duration shall become clearer over the next few weeks. Access to the area has also been restricted as part of precautionary measures.

Consultations with various specialist stakeholders, including the original equipment manufacturer, are in progress to determine best course of action to restore the plant as quickly as possible.

The failed section of the Unit 1 flue gas duct is located inside the flue chimney. The ducts are made from steel sections welded together and surrounded by a windshield, which is made of reinforced concrete that also houses the Unit 2 and Unit 3 flue gas ducts.

Unit 2 was off load at the time while Unit 3 was generating electricity.

Unit 4, whose FGD duct is housed on a separate flue chimney, is currently on load  generating full load to the national grid.

As part of precautionary measures put in place, the return to service of Unit 2 has been put on hold while Unit 3 continues to run at stable load.