TRISTEN TAYLOR: A perfect storm for a nuclear accident is brewing at Koeberg

Eskom’s project to extend the life of Koeberg’s two reactors for another 20 years is the very definition of crisis management.

Described at the state-owned power company as getting the licence for long-term operation (LTO), the project is well behind schedule, and Koeberg’s licences run out in July next year. If the LTO isn’t completed by then it will have to shut down the plant’s two reactors.

But that impending financial and load-shedding disaster is not the real emergency. Koeberg simply is not safe.

After inspecting Koeberg, the International Atomic Energy Agency (IAEA) handed Eskom a report in March 2022 detailing what was necessary for a safe LTO. Eskom’s “Safety Case for Long-Term Operation of Koeberg Nuclear Power Station” report was completed in July 2022 as part of its submission to the National Nuclear Regulator (NNR) to justify the life extension.

Neither of these documents was intended for public consumption. The DA had to use the Promotion of Access to Information Act to get hold of the IAEA report, and the NNR forced Eskom to put the 290-page report into the public domain, which it did in January 2023 — but only after severely redacting the document, for no apparent reason.

A separate confidential submission was made to the NNR on the plant’s physical and cybersecurity. Appendix D, which deals with the prevention and mitigation of a nuclear accident, is an exemplar of redaction. Of the appendix’s 24 pages, 16 are fully blacked out and four are either partly or almost entirely redacted.

In other words, the details of Koeberg’s strategy to prevent, contain and deal with a meltdown, partial meltdown, reactor vessel rupture and/or explosion, are being withheld without good cause.

The IAEA’s report identifies 15 areas where Koeberg’s safety is doubtful. One of the major concerns is the integrity of the outer containment vessels and a poorly functioning containment vessel monitoring system. In effect, if there is a problem with either reactor Eskom is unable to accurately determine the pressure inside the containment vessel.

Koeberg’s containment structures suffer from cracking concrete, large-scale delamination and the corrosion of reinforcing bars. Temporary repairs have persisted since 2000, and by Eskom’s own admission in 2017, environmental conditions and delayed maintenance had caused the damage. According to the IAEA, the concrete repairs might have caused the malfunctioning of some elements within the monitoring system.

A separate but related matter deeply worried the IAEA. All reactors develop cracks over time due to neutron embrittlement. Under certain conditions a fast fracture may appear, with potentially catastrophic results. In the case of disaster and the subsequent rise in pressure, the outer containment vessel has to hold. If it doesn’t, the question is which way the wind blows. The IAEA did not have the appropriate information in 2022 to determine reactor safety because Eskom had yet to even contract fast fracture analyses.

To be sure that the containment structure will not breach, Eskom needs to check the leak-tightness and structural integrity of the building. The last integrated leak test for both reactor units was in 2015. Unit 1’s next test is slated after the July 2024 deadline. In January the NNR will decide whether to grant Eskom’s request to extend the deadline for Unit 2 to November 2025, on the basis that the unit was commissioned a year after Unit 1.

Eskom also needs to replace components of the containment monitoring system. The safety case report states that a “purchase request is initiated” and that repairs will only be made after July 2024. Yet the IAEA states that Koeberg “should ensure full functionality of the containment structure monitoring system”.

Since there  is no guarantee an accident will not happen in the next eight months, having fully functioning containment vessels now is nonnegotiable. However, based on the 2015 integrated leak test and the temporary repairs, Eskom disagrees, saying that “the current condition of the buildings is deemed to have sufficient integrity, and the design of the buildings remains fit for purpose and suitable for long-term operation.”

Electrical cabling does not meet IAEA safety standards. Koeberg has wetted cables, problems identifying individual cables, overloaded cable trays, cables bunched together as they pass through firewalls, and poor illumination in some cable corridors. The IAEA says that “without a complete revalidation of environmental qualification of cables, the ability to perform their safety functions cannot be demonstrated”.

Cable failure could, for example, blind the control room to a serious problem within the plant. Eskom has known since 2009 that it would most likely need to replace both cables and switchboards. While sampling of some cables is happening, it is far from obvious that this is the complete revalidation the IAEA wants.

The IAEA pointed out 13 other areas of concern. For example, Eskom let its subscription to Westinghouse’s POMS software expire. The POMS system tracks obsolescence in 12-million plant components and provides an up-to-date database of 30,000 suppliers. Worldwide, 170 nuclear reactors use POMS, and Westinghouse designed Koeberg.

Without this software Eskom does not know when individual parts will reach end of life and who to buy replacements from. The IAEA says “the plant does not have access to any tool to proactively identify obsolescence”.

The IAEA is perturbed that the “management of the LTO programme is not effective to timely complete all actions to prepare for [the] LTO”. When the agency visited Koeberg the software tracking the LTO process was unavailable due to technical problems.

Eskom has not done a complete assessment of electromagnetic compatibility, which would prevent the kind of electromagnetic inference that has caused safety problems in other plants: for example, emergency reactor shutdowns, erroneous readings in the control room and false dosimeter readings. The IAEA indicates that Eskom has known of the need for an assessment since 2015.

About 250-300 skilled employees left Koeberg between 2021 and 2022. After 27 years at Eskom its chief nuclear officer, Riedewaan Bakardien, left last year for a job at a Canadian power company. In 2016 Bakardien had been suspended temporarily for questioning the LTO’s viability.

It is likely that his worries included the leakage from the sumps, the contents of which are highly radioactive, in Nuclear Auxiliary Building 2. The building houses the reactor’s backup safety systems.

Eskom’s COO at the time, Jan Oberholzer, said that the skills exodus was a risk to the LTO. Oberholzer retired in April, returned on contract to oversee the LTO and tendered his resignation in mid-July.

The reality is that the conditions conducive for a nuclear accident at Koeberg are present. The IAEA has serious safety concerns. Eskom is under tremendous political pressure to finish the LTO. A dangerous culture of secrecy prevents scrutiny. And experienced employees are leaving in droves.

The handbrake has to be pulled. The IAEA needs to do a fresh investigation, and the redactions must go. In 2022, a Koeberg worker cut the wrong safety valve during routine maintenance. That worker was not even at the right reactor. Eskom said back then that the “significant error” could have had “devastating consequences”.

Our atomic luck may not hold next time.

• Dr Taylor, a freelance journalist and photographer, is research fellow in environmental ethics at Stellenbosch University.