The first Unit 1 steam generator at the Koeberg power station has been removed from the containment building and placed into an on-site storage building – a development that Eskom describes as a major milestone for a project that has had numerous false starts during previous outages.

However, the State-owned utility has also confirmed that, as a result of “unexpected challenges” during the current long-duration outage, the original return to service date of early June is “no longer achievable”.

“Although every effort is being made to reduce the impact, we are currently running a few weeks late,” Eskom said in a statement, adding that the generation production plan was being updated to minimise the impact of the projected delay.

The removal of the first steam generator came only days after the National Nuclear Regulator (NNR) announced that the 60-day period for receiving written representations from members of the public on Koeberg’s application to operate beyond its mid-2024 licence expiry date had closed.

While central to the utility’s plan to extend the life of the nuclear power station for a further 20 years, the replacement project has faced heavy criticism from both environmental groups and energy commentators.

Environmental opponents to the extension have already raised concerns about the consultation process being pursued by the NNR and have also expressed anxiety about the safety case for the life-extension, as well as with the project’s rising costs and corruption at Eskom.

Questions are continually been raised about the direct and indirect costs of the project, with Eskom having acknowledged that the 2010 cost estimate of R20-billion is no longer accurate but has not yet provided a revised expenditure figure.

The indirect costs, meanwhile, have also been calculated to be substantial, given ongoing loadshedding and the fact that having a Koeberg unit out of service for most of 2023 will add one stage to loadshedding when such cuts are implemented.

Once the Unit 1 replacement is completed, Eskom intends pursuing a similar long-duration outage at Unit 2, leaving Eskom without electricity production from half of Koeberg for most of 2023.

The Unit 1 outage began on December 10 and was expected to continue for about 180 days, while Unit 2 will be shut in September for a similar period after a previous attempt to replace the steam generators was postponed when it emerged that Eskom’s storage facilities had not been completed in time.

Eskom insists, however, that the new steam generators are the last large component replacements needed to ensure Koeberg can operate safely for the requested additional 20-year period.

It also underlines the engineering and logistical complexity of the removal of the first steam generators, explaining that it involved moving steam generators that are installed vertically and taking them out of the containment building horizontally at an elevation of 20 m before placing them on a flatbed transporter.

In a statement Eskom noted that each steam generator is 22 m long, or the height of a six-story building, and weighs over 320 t, which the utility notes as being heavier than a Boeing 747.

Eskom also indicates that the removal and replacement of Unit 1’s other two steam generators will involve the following sequence of activities:

Rigging the remaining two steam generators out from their positions inside the containment building;

Rigging the three new steam generators into their exact position inside the containment building;

Performing six critical welds (two on each steam generator) that join the steam generators to the primary system piping;

Performing radiography on the welds to ensure they meet the code requirements;

Reinstalling all the access platforms that enable people to work all the way up the steam generators (seven stories of permanent structures and temporary scaffolding);

Reinstalling all the other piping connections (steam pipe at the top, feedwater pipe, and all the other smalle...