Eskom has uncovered at least one other unsafe silo at a power station. This as the state-owned power utility was forced to conduct inspections of its coal silos after the collapse of a silo at the Majuba power station.
One silo at the Tutuka station, also in Mpumalanga, posed “potential risks”, leading to “preliminary mitigation measures”, according to Eskom.
The power utility said it found “small indications” on two of Tutuka’s silos. It has reduced the maximum operating levels of these silos to 50% to reduce operational stresses on the structures.
“The two silos will be taken out of commission one at a time during the next week to perform internal inspections as well.”
Tutuka was completed in 1990 and Majuba in 2001. They are relatively new stations, by Eskom’s standards.
According to Eskom, a “programme is in progress to inspect all silos”.
Apart from the Tutuka silo, one silo at the Lethabo station in the Free State, silo 3, was inspected and revealed no defects, Eskom said.
Meanwhile, the lost generation due to the Majuba silo collapse earlier this month has pushed Eskom into exhausting its emergency power capacity.
Diesel and water-powered peaking plants have run dry, forcing the power utility to institute “stage one” load shedding on Friday afternoon.
Stage one involves cutting demand by 1?000 megawatts while peak demand is about 33?000MW. Various municipalities increased load shedding to stage two within hours.
The peaking plants include the diesel-fired generators in the Western Cape and the newly constructed Ingula pump storage plant.
The unprecedented levels of unplanned generation outages this month have meant that these emergency measures are being overused.
According to Eskom’s twice-weekly system updates, the level of unplanned outages in the system has stayed above 7?700MW since the collapse of the Majuba silo.
Before this month, the average level of unplanned outages had been about 5?200MW.
Before this year, 5?000MW was considered high, the target being to keep it below 4?000MW.
Alongside concerns about the effects of cutting back on planned maintenance on power stations in Eskom’s aging infrastructure, the state of the company’s relatively uncomplicated – and relatively new – coal silos is beginning to raise eyebrows.
Trade union Solidarity this week said Majuba’s silo 30, adjacent to the collapsed silo 20, had cracks near the top.
Eskom confirmed this, saying it had discovered the crack soon after silo 20 collapsed on November 1.
“The position of the defects near the top of the silo is such that they do not pose a risk to the structural stability of the silo.
“These defects have been assessed by structural engineers and it was confirmed that the defects are not significant in terms of safety risk,” said Eskom.
The two remaining silos, silo 10 and silo 30, are now empty after the collapse of silo 20, which stands in the middle and connects to the station and the other silos by means of conveyer belts.