The National Nuclear Regulator (NNR) has confirmed that it is in preliminary talks with State-owned national electricity utility Eskom regarding extending the operating life of the country’s only nuclear power plant (NPP) at Koeberg, north of Cape Town. Currently, Koeberg is licensed by the NNR to operate until 2024. Eskom wishes to extend the NPP’s operating life by 20 years, and informed the NNR of this in July. The utility will make its formal application to the NNR for a licence for ‘Long Term Operations’ at Koeberg early next year.
“The prime responsibility of the NNR is to, amongst others, exercise regulatory control over the siting, design, construction, operation, manufacture of component parts, decontamination, decommissioning and closure of nuclear installations to protect people and the environment from the harmful effects of ionising radiation,” explained the NNR. “The NNR discharges this responsibility through a process of conducting authorisations, attaching conditions to authorisations and overseeing compliance to regulatory requirements.” Prime responsibility for complying with NNR requirements, approvals and procedures lies with the holder of the authorisations/licensee.
Currently, the NNR is in talks with Eskom regarding the scheduling of the licensing, and associated matters, for Long Term Operation of the Koeberg NPP. This includes the conclusion of the Third Periodic Safety Review for Koeberg. The NNR has already concluded its review of the basis document for the Third Periodic Safety Review, as well as of the licensing strategy for Long Term Operations at the NPP.
Meanwhile, Eskom has already started some operations necessary to extend Koeberg’s life by the desired two decades, but which only peripherally involve the NNR. These are the removal of the NPP’s old steam generators and the installation of new ones. The NNR has assured that this process involves no nuclear safety issues, as each reactor (Koeberg has two) is both shut down and defueled while its associated steam generators are replaced.
Steam generators are heat exchangers, used in pressurised water reactor (PWR) NPPs such as Koeberg. In PWRs, water in a closed circuit (known as the primary circuit) is pumped through pipes in the core of the reactor, to cool it; this water becomes extremely hot but, because it is under pressure, it does not boil. This superhot water is then pumped to a heat exchanger – the steam generator. Here, the heat from the primary circuit water is transferred to water in a completely separate secondary circuit (the water in the two circuits never mixes) which becomes superheated steam, which then drives a turbine to generate electricity.
However, what the NNR does do during the process of the removal of the old steam generators is monitor radiation doses experienced by the workers, not only to ensure that they are within regulatory requirements, but that they are as low as practically possible. To this end, NNR inspectors will monitor all important phases of both the removal of the old steam generators and the installation of the new ones.
Eskom has informed the NNR that it wishes to store the old steam generators in a new facility at the Transient Interim Storage Facility at Koeberg. This requires regulatory approval from the NNR, which the utility has applied for and the regulator is currently considering. The steam generators would be stored at this facility for some ten years after the end of commercial operations at the NPP. Thereafter, the old steam generators would be moved to the Vaalputs National Waste Disposal Facility in the Northern Cape province. That would also require NNR approval, both for their transport and their storage there.