MATSHELA KOKO
DURBAN - On August 26, 2021, the National Energy Regulator of South Africa (Nersa) made the correct decision to support the 2 500MWe Nuclear New Build Programme.
This is a move that will decarbonise the country’s electricity sector and provide the desired power quality into the future at a cost and pace that South Africa can afford.
This is a realisation that the varying demand imposed on the electricity grid now and in the future can best be met with a mix of generating plants which should include nuclear power, renewable technologies, and gas to power plants.
Koeberg power station is the continent's only operating nuclear power plant. The decision to build it was taken by the then minister of mines and planning in May 1968 pursuant to the report prepared by the then Atomic Energy Board’s Nuclear Power Committee, the chairperson of which was Dr HJ van Eck.
The 1968 decision to build the Koeberg power station was motivated by the need for a just transition to conserve the water used for power generation in South Africa. The Vaal River carried the heaviest burden for power generation, at an average of 165 million litres a day of the raw water intake for the year 1966.
Part of the explanation for the just transition to conserve the water used for power generation is found in the severe restrictions which were imposed on the use of water from the Vaal River Basin.
The restrictions were in force during the greater part of 1966 and, as a result, the amount of electricity used for pumping water was substantially lower than in the previous years. This elevated the real essence of the water and electricity nexus. The water and electricity nexus was very important to understand due to the increasing electricity demand and the decreasing freshwater quality.
It was because of the severe water restrictions in 1966 that Grootvlei Power Station was selected as a station at which a generating set using dry cooling towers would be installed, to gain experience in the use of this system for condensate cooling under South African conditions. Grootvlei power station replaced an older generation of power stations and is located within the Vaal River basin.
Dry cooling towers consist of a draft-inducing shell at the base of which several pure aluminium heat exchangers are mounted, and cooling of the water takes place in a closed circuit by convective heat transfer on the same principle of a motor car radiator.
The method of condensate cooling increased both the power station construction and operating costs by about 10% and it is adopted where there is insufficient water for wet cooling. The raw water intake would be reduced from 2.2 litres per kilowatt sent out for the wet cooling system to 0.1 litres per kilowatt sent out for the dry cooling system.
The premium that came with the transition from the wet cooling system to dry cooling technologies was considered a small price to pay to conserve the water used for power generation.
In 1966, Eskom issued the enquiries for the supply and installation of a 200MW boiler and turbogenerator set at Grootvlei power station. The turbogenerator set was to be designed for dry cooling either by the direct or indirect system.
Tenders were received in March 1967. The dry cooled unit at Groovlei went into commercial operation in May 1971 and it had the largest cooling tower of the type in the world. It was a prototype tower that was meant to materially assist in the planning and designing of future power stations.
The experiment at Grootvlei power station was a game-changer. Eskom is today one of the world’s acknowledged leaders in the field of applied dry cooling technologies. Majuba units 1-3, Kendal, Matimba, Medupi and Kusile power stations are among the largest dry-cooled installations in the world.
The transition from wet cooling technologies to dry cooling technologies was a big step change in the conservation of water used for power generation.
However, the scientists and engineers were determined to do more to conserve the water used for power generation particularly in the areas where coal resources were located. It was for this reason that, in May 1968, the Ministry of Mines and Planning took a decision to build Africa’s first nuclear power station at the coast where seawater was to be used for condensate cooling purposes.
A condition precedent to the introduction of Africa’s first nuclear power station at the coast was the completion of a nationwide high voltage transmission network. The network would allow for the flow of power generated at the coast to the interior. The network would also enable electricity to flow from the highveld to the coast.
During 1970 and the early months of 1971, Eskom’s programme of transmission line construction suffered serious setbacks, mainly due to shortages of steel and cement. As a result of the delays, the projections at the time were that the 400kV transmission line from Gauteng to the Western Cape would be energised by the early 1980s.
Based on the projections and in early 1974, it was decided that the first nuclear unit of the capacity in the range of 800 to 1000MW would be commissioned in the second half of 1982. A second unit would come into operation a year later.
It made perfect sense that a large nuclear set installed in the Western Cape would be more economical than the combined costs of an inland coal-fired unit of equivalent capacity together with the associated transmission system to the Cape.
An enquiry for either a pressurised water reactor or a boiling water reactor system was issued in February 1974. In April 1975, three tenderers were selected from the five suppliers who had submitted tenders, and the three were invited to make final submissions for the construction, on a turnkey basis, of Africa’s first nuclear power station 25km north of Cape Town.
The contract was signed in August 1975 for the design, construction and commissioning of two nuclear generating sets each with a nett electrical output capability of 922MW. The two generating sets were scheduled for commercial operation by the end of December 1982 and 1983 respectively.
The construction programme for Africa’s first nuclear power station was disrupted by acts of sabotage at the end of 1982. The commissioning and raising to the power of Koeberg’s first unit was completed and taken over in July 1984. It attained 2 000 effective full-power hours in a shorter time than any similar set at a French-built nuclear power station.
This achievement was attributed to the policy of acquiring a power plant that is largely identical to units previously manufactured and commissioned in the supplier’s own country. By the end of 1984, the second unit was licensed to load fuel and pre-critical testing began.
The first phase of the just energy transition was driven by the need to conserve the water used for the generation of electricity. Because of South Africa’s limited water resources, Eskom has, since the 1960s, improved dry cooling technologies to such an extent that the latter can be used successfully in future power stations including at Medupi and Kusile power stations.
Eskom was also forced to build Africa’s first nuclear power station at the coast where seawater was used for condensate cooling purposes in order to conserve the water used for power generation in the areas where coal resources were located. Koeberg power station is today the cheapest generating power station in the Eskom fleet.
The second phase of a just energy transition is driven by the decarbonisation of the electricity sector. On September 20, 2021, the cabinet approved tougher greenhouse gas emission targets ahead of the 2021 UN Climate Change Conference of Parties, also known as COP26.
For some strange and inexplicable reasons and in pursuit of the tougher greenhouse gas emission targets, Eskom plans to repower Komati using a solar photovoltaic plant supported by 244 MWh battery storage. Similar projects are planned at the Grootvlei, Hendrina and Camden power plants, all of which were scheduled for closure by 2025.
Komati, Grootvlei, Hendrina and Camden Power Stations have a combined capacity of 5 700MW. To suggest that the power stations can be repowered using solar photovoltaic plants supported by battery storage is fantastical.
COP26 takes place at the opportune time after the first of two high-temperature gas-cooled reactors at Shidaowan in China’s Shandong province, attained a sustained chain reaction for the first time on September 12, 2021. The reactor is scheduled to be connected to the electricity grid before the end of this year. The nuclear power plant at Shidaowan features two small reactors that will drive 210 MWe turbine.
Nersa’s decision of August 26, 2021, to support a long-term government plan to build new nuclear power units, is as important as the decision by the then minister of mines and planning in May 1968 to build the first nuclear power station on African soil.
What makes the Nersa decision great in its significance is that it places South Africa in a position to build a conventional nuclear unit at the current nuclear-licensed site near Melkbosstrand and a 200-300MWe small modular reactor at Phelindaba by 2032. The new nuclear power stations must be identical to units previously manufactured and commissioned in the supplier’s own countries.
The first phase of our just energy transition was driven by the need to conserve the water used for power generation. Our forebears did three things: first, they made us the leader in the field of applied dry cooling technologies; second, they built the nationwide high voltage transmission network to create a single national electricity grid; and finally, they built Africa’s first nuclear power station at the coast where seawater would be used for condensate cooling purposes.
The second phase of the just energy transition is driven by the tougher greenhouse gas emission targets that were adopted by the Cabinet on September 20, 2021, and by the need for electricity security that must come at a cost that will drive economic development.
For this, we need a mix of generating plants which includes nuclear power, renewable technologies, and gas to power plants and, most importantly, the expanded high voltage transmission network. Just like Grootvlei power station replaced older generation of power stations, small and modular nuclear power stations will replace coal power stations in the Highveld.
From the comfort of my home, I sense a nuclear revolution. It is just a matter of time.
Matshela Koko, Eskom's former interim group chief executive
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