Eskom has confirmed that no radiation leak occurred during routine maintenance at Koeberg Nuclear Power Station's Unit 2, assuring the public that there was no risk to employees, surrounding communities or the environment.
In a statement issued on Sunday, the utility said the incident, which occurred during scheduled maintenance inspections in July, was classified as Level 0 (no safety significance) on the International Nuclear and Radiological Event Scale (INES) – the lowest possible rating.
"The event had no impact on nuclear safety, plant operations, employees, the public or the environment," Eskom said, adding that the National Nuclear Regulator (NNR) had been notified in accordance with regulatory requirements.
Unit 2 has been on a planned maintenance outage since April 2026 and remains on schedule to return to service in November. Koeberg's Unit 1 continues to operate normally.
Eskom said highly sensitive radiation monitoring equipment detected two brief and localised airborne radioactivity events inside a controlled work area within the Unit 2 containment building on 2 and 7 July during routine steam generator inspections.
The utility stressed that the detections were confined to the designated work area inside the containment structure and did not result in any release of radioactive material beyond the plant's protective barriers.
As a result, there was no need to administer iodine tablets to employees.
According to Eskom, the airborne activity occurred during Eddy Current Testing (ECT), a standard non-destructive inspection method used worldwide to assess the condition of steam generator tubes.
During the inspection, a minute quantity of microscopic oxide particles, commonly known in the nuclear industry as "crud", became airborne within the enclosed work area.
The inspections are conducted using robotic probes to establish a baseline of the steam generator tubes and identify signs of wall thinning long before they could affect plant performance or safety.
Eskom said minor airborne particulate events of this nature are a recognised phenomenon during steam generator inspections at pressurised water reactors globally and are managed through robust safety systems.
The utility said Koeberg's multiple layers of safety and containment functioned exactly as designed.
These included physical containment barriers, high-efficiency particulate air (HEPA) filtration operating under negative pressure, continuous airborne radiation monitoring through Constant Air Monitors (CAMs), and comprehensive radiation protection measures for personnel.
When the monitoring equipment detected the temporary increase in airborne activity, it automatically triggered an alarm.
In response, plant personnel immediately halted the inspection, secured the work area, allowed ventilation and filtration systems to remove the airborne particles, and carried out the required radiological assessments before maintenance resumed.
"These actions successfully contained the material within the designated work area and restored conditions to normal operating parameters," Eskom said.
The utility said monitoring confirmed that the airborne particles remained confined to the controlled work area and that no radioactive material was released into the environment.
"The 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."
Eskom said the incident had no impact on the safe operation of the power station, maintenance activities or the planned completion date of the Unit 2 outage. Personnel involved were also provided with a comprehensive safety debriefing following the incident.
The utility reiterated its commitment to maintaining the highest standards of nuclear safety, regulatory compliance and transparency in the operation of South Africa's only nuclear power station.
In a statement issued on Sunday, the utility said the incident, which occurred during scheduled maintenance inspections in July, was classified as Level 0 (no safety significance) on the International Nuclear and Radiological Event Scale (INES) – the lowest possible rating.
"The event had no impact on nuclear safety, plant operations, employees, the public or the environment," Eskom said, adding that the National Nuclear Regulator (NNR) had been notified in accordance with regulatory requirements.
Unit 2 has been on a planned maintenance outage since April 2026 and remains on schedule to return to service in November. Koeberg's Unit 1 continues to operate normally.
Eskom said highly sensitive radiation monitoring equipment detected two brief and localised airborne radioactivity events inside a controlled work area within the Unit 2 containment building on 2 and 7 July during routine steam generator inspections.
The utility stressed that the detections were confined to the designated work area inside the containment structure and did not result in any release of radioactive material beyond the plant's protective barriers.
As a result, there was no need to administer iodine tablets to employees.
According to Eskom, the airborne activity occurred during Eddy Current Testing (ECT), a standard non-destructive inspection method used worldwide to assess the condition of steam generator tubes.
During the inspection, a minute quantity of microscopic oxide particles, commonly known in the nuclear industry as "crud", became airborne within the enclosed work area.
The inspections are conducted using robotic probes to establish a baseline of the steam generator tubes and identify signs of wall thinning long before they could affect plant performance or safety.
Eskom said minor airborne particulate events of this nature are a recognised phenomenon during steam generator inspections at pressurised water reactors globally and are managed through robust safety systems.
The utility said Koeberg's multiple layers of safety and containment functioned exactly as designed.
These included physical containment barriers, high-efficiency particulate air (HEPA) filtration operating under negative pressure, continuous airborne radiation monitoring through Constant Air Monitors (CAMs), and comprehensive radiation protection measures for personnel.
When the monitoring equipment detected the temporary increase in airborne activity, it automatically triggered an alarm.
In response, plant personnel immediately halted the inspection, secured the work area, allowed ventilation and filtration systems to remove the airborne particles, and carried out the required radiological assessments before maintenance resumed.
"These actions successfully contained the material within the designated work area and restored conditions to normal operating parameters," Eskom said.
The utility said monitoring confirmed that the airborne particles remained confined to the controlled work area and that no radioactive material was released into the environment.
"The 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."
Eskom said the incident had no impact on the safe operation of the power station, maintenance activities or the planned completion date of the Unit 2 outage. Personnel involved were also provided with a comprehensive safety debriefing following the incident.
The utility reiterated its commitment to maintaining the highest standards of nuclear safety, regulatory compliance and transparency in the operation of South Africa's only nuclear power station.
