A nuclear unit tripped off the grid, and the margin absorbed it.

For a large power user that worries about supply after dark and through winter, the utility's weekly performance statement records a nuclear unit leaving the grid with no effect on the utility's ability to meet demand. During testing linked to Koeberg Unit 2's planned maintenance outage on the morning of 16 October 2026, a protection system on Unit 1 operated for a disturbance beyond its tolerance limits and opened the unit's 400 kV and 24 kV breakers, taking it offline. Engineering teams are investigating what caused the protection to operate, and the utility reported no nuclear safety concerns, with the station safe and stable and its safety systems in service.

The same statement puts fleet availability for the financial year to 15 October 2026 at 68.2%, against 62.63% over the same months last year, and calls that the strongest at this stage of the year in six years; unplanned outages, as a share of capacity, came down to 18.9%. Spare capacity stood at 5 695MW, and the evening peak forecast for the day was 23 966MW against 26 143MW available with gas excluded. Diesel has almost left the picture: spending on it for the year to date fell by R4.87 billion to R1.18 billion, and the load factor on the open-cycle gas turbines was 0.95%, well inside the 3% annual target. Load shedding has now been absent for 518 days in a row, counted from 16 May 2025.

Read together, those figures describe a reserve margin that is working rather than sitting on paper: the loss of a nuclear unit was taken up on a day when the turbines that once covered such gaps were idle, with roughly 2 177MW standing between the forecast peak and available capacity before the trip.

For large power users, a margin this wide changes what you can reasonably ask for rather than what you are owed: firmer answers on interruptibility, and a clearer view of what the site can draw at the evening peak. It is worth asking your supplier what notice you would have if that margin narrowed again over winter, and checking whether your supply agreement still prices curtailment as though the scarce years were the norm. The gap between forecast peak and available capacity, rather than the headline availability figure, is the number to follow.