Senior energy officials representing South Africa’s power company Eskom, the National Nuclear Regulator (NRR), the Department of Electricity & Energy (DOEE), and the South African Nuclear Energy Corporation (Necsa) briefed the media on recent radiation contamination events reported at the Koeberg NPP.
The briefing was held after the NRR revealed that it was reviewing radioactive contamination events at unit 2 of the plant which has been on a scheduled outage since April 2026.
The incidents occurred during scheduled steam generator Eddy Current Testing (ECT) inspections. Chief Nuclear Officer at Eskom, Velaphi Ntuli, said the events occurred on 30 June, 2 July and 7 July during maintenance work, with a fourth event taking place on 16 July. All were classified as Level 0 (No Safety Significance) on the International Nuclear and Radiological Event Scale (INES), indicating that there was no impact on nuclear safety, plant operations, employees, the public or the environment.
“At no stage was there any release of radioactive material beyond the containment structures, and there was no risk to surrounding communities or the environment”, Ntuli noted. “During scheduled inspections of the steam generators that are used to produce electricity, highly sensitive radiation monitoring equipment detected two brief and localised airborne radioactivity events within a controlled work area inside the containment building on 2 and 7 July.” Ntuli said that the affected work area was protected by multiple engineered and administrative controls, in line with both local and global standards.
He added: “These detections were confined to the designated work zone, remained well within the plant’s protected barriers and were managed in accordance with established radiation protection procedures. The event was safely managed to international standards by Koeberg’s highly trained teams, with no impact on nuclear safety, plant operations, maintenance activities or the planned scheduled outage completion date of November 2026. The outage remains on schedule, and Koeberg Unit 1 remains in full operation.”
ECT inspections are performed using operated robotic equipment probes positioned inside part of the steam generator. During the movement of the inspection probes through the steam generator tubes, a very small quantity of microscopic oxide particles, commonly referred to in the nuclear industry as “crud”, became airborne within the enclosed work area.
Eskom said that the purpose of ECT is to establish a baseline for tubes inside the steam generator and the thickness of the tubes to identify any signs of wall thinning long before they could affect plant performance or safety, and to maintain the integrity of the barrier between the reactor coolant system and the secondary steam system.
Eskom added that minor airborne particulate transients of this nature are a well-understood and documented phenomenon that can occur during steam generator inspection activities at pressurised water reactors worldwide. “The industry employs robust containment, ventilation and monitoring systems specifically to detect and manage such occurrences safely.”
According to Eskom, the event did not affect the safe operation of the station and maintenance activities have continued under established safety controls. The personnel were provided with a full safety debriefing following the event. “This event demonstrated the effectiveness of Koeberg’s defence-in-depth approach, with monitoring, containment and radiation protection systems functioning as designed and providing early detection and control of the transient.”
