Eskom isn’t bothering with critical Koeberg upgrades — expert

South Africa’s state-owned power utility Eskom has been quiet about nuclear safety concerns raised surrounding the Koeberg Power Station earlier this month.

Neil Overy, a Research Associate in Environmental Humanities at the University of Cape Town, said Eskom is bankrupt and cutting corners by foregoing critical upgrades at Koeberg.

MyBroadband asked Eskom to respond to Overy’s claims and, if confirmed, provide details about why Koeberg won’t be getting these upgrades.

However, it didn’t answer the questions directly and listed a range of safety improvements that it had implemented.

It said modifications to the reactors to improve safety and reliability included replacing refuelling water storage tanks, reactor vessel beds, the turbine protection and control system, and the reactivity control rod system.

Eskom also upgraded Koeberg’s radioactivity monitoring system and the spent fuel cooling system.

“Koeberg has committed to further safety improvements by investing in additional seismically robust cooling water supplies and improved reactor cooling pump seals, to name a few,” said Eskom.

“The defects on the containments from 2017, have been repaired. The crack in the dome of the containment building does not affect the structural integrity of the containment building.”

It added that the crack had been sealed and painted over, as it doesn’t affect structural integrity. Eskom said the crack was monitored during containment building pressure tests and evaluated by international experts.

“If a leak is confirmed, there are detailed procedures to identify and repair the liner of the spent fuel pools. These types of leaks are extremely small and holds no risk in terms of the safety of the fuel and is not discharged to the environment but contained,” Eskom added.

Koeberg is South Africa’s only nuclear power station and a critical component of its electricity generation mix. When running at full capacity, it contributes nearly 2,000MW to the grid.

Its two reactors have been undergoing maintenance to replace their stream generators — work that is crucial to getting a licence from the National Nuclear Regulator to extend their lives by another 20 years.

Eskom completed the work on Koeberg’s unit one generator in November 2023 and took the second unit offline for similar work in December.

Koeberg’s nuclear licence expires next month, so Eskom must complete the work by then, or the power station will be forced to shut down.

However, according to Overy, Eskom won’t carry out certain “non-negotiable” upgrades.

The Koeberg Power Stations were built by the French nuclear power company Framatome. They were designed similarly to 18 nuclear reactors in France.

Like Koeberg, the French nuclear reactors are undergoing life extension projects.

However, Overy said the work being done on the French reactors is far more extensive than what’s happening at Koeberg Power Station.

Koeberg’s nuclear reactors, as well as the 18 in France, are considered generation-two reactors, while the rest of the industry has moved to generation-three generators.

“You can’t create a generation-three nuclear power station out of a generation-two one,” said Overy.

“But lessons have been learnt from nuclear accidents in the intervening period, and France is upgrading certain elements within the nuclear power station that is not taking place at Koeberg.”

The French nuclear regulator has also identified a new upgrade — the “core catcher” — as non-negotiable for generation-two reactors.

The bowl-shaped core catcher sits below the reactors and is designed to stop molten core, or corium, from leaking onto the ground and into the water below.

The French nuclear regulator wants core catchers installed under generation-two nuclear reactors to mitigate the consequences of a core meltdown.

“Eskom is saying we don’t need that here,” said Overy.

He added that other critical safety aspects are being overlooked at Koeberg, mostly related to ongoing maintenance, such as testing the pressure of containment vessels.

“If there’s a major accident within the containment vessel, you don’t want it to explode or leak in any way,” said Overy.

The French nuclear regulator stipulates that these pressure tests must be carried out every five years. However, Eskom only plans to test the vessels every ten years.

Another point of concern is that the French nuclear regulator will only license nuclear power station life extensions with the same design as Koeberg for ten years.

Eskom is applying for a 20-year extension at Koeberg Power Station.

“I think that one of the reasons why the safety standards are not being adhered to in the same way in South Africa is because Eskom is bankrupt, and Treasury isn’t going to push any more money its way,” said Overy.

“There’s also a desperate need to keep the lights on.”

Despite all this, Overy emphasised that the risk of a nuclear meltdown in South Africa is minimal. However, if a nuclear accident were to occur, the consequences would be disastrous.