Eskom is considering tried-and-tested nuclear solutions

Last week, I expressed the view that the nuclear build programme must be driven by a targeted levelised cost of lower than R1 per kilowatt hour. As I have said, Eskom aims to replicate Koeberg’s success and aims for a standardised design with no leadingedge technology. There have been suggestions Eskom is looking to buy lesssafe nuclear reactors to reduce the cost of the nuclear build programme, the so-called Generation 2, rather than the modern Generation 3 reactors. This is not the case.

The issue of what makes a Generation 2 design versus a Generation 3 design is interesting and has never been well defined. All vendors of the current nuclear power plants claim that their nuclear reactors are Generation 3 or Generation 3 plus and that their competitors’ designs are Generation 2 plus.

Probably the best definition of the difference between Generation 2 and 3 is that the early designs (dating from the 1960s and 1970s) considered that the prospect of a core melt accident was impossible and could be ignored in the design. These are called Generation 2 designs.

Following the Three Mile Island accident in 1979, it was realised that core melt was possible and future designs involved different philosophies to manage such an event.

The designs that were started on this basis are now called Generation 3 designs. In reality, design practices and standards in the nuclear industry have been evolving over time, as with all technologies, and the use of the Generation 3 and Generation 3 plus is largely a marketing discussion.

When Eskom started looking at new nuclear plants to add to its generation fleet, it looked in detail at all the available designs.

Clearly the safety features were the critical areas of assessment.

In this review, Eskom recognised that the need to design plants to meet stringent modern safety requirements could lead to several different solutions, of similar effectiveness.

Clearly the need to meet the local National Nuclear Regulator and the International Atomic Energy Agency standards is non-negotiable.

Early on, in about 2006, Eskom adopted an approach of using the European Utility Requirements as the basic benchmark for any new design it would have undertaken.

It is a very detailed set of requirements for large, light-water reactors that were established in the 1990s by a very large number of European utilities. It is by far the most rigorous set of standards in the world.

In looking at the various designs (EPR from Areva, AP1000 from Westinghouse, APR1400 from Kepco, VVER 1200 from Rosatom, CAP1400 from SNPTC of China, APWR from Mitsubishi etc), all of which claim to be Generation 3 designs, it was clear that while they all aim to meet similar levels of safety, they had very different design approaches.

Some nuclear companies, such as Areva and Rosatom, considered that the systems must be able to manage a core if it melts through the bottom of the pressure vessel, so they install a “core catcher”.

Others such as Westinghouse and SNPTC plan to provide external cooling to the pressure vessel to avoid melting through.

Some companies — such as Areva, Kepco and Mitsubishi — considered the best safety system performance is by many redundant powered systems; others such as Westinghouse and SNPTC by unpowered (“passive”) systems, and Rosatom installs both approaches in parallel.

The list of differences goes on. So, depending on which vendor you speak to you get a different explanation of why their design is “more advanced” than the competitors.

Eskom’s view is that all the designs available on the market today meet international standards and have the potential fully to meet the National Nuclear Regulator requirements.

Eskom is looking for a modern standardised design that is under construction in the country of origin as a substantive domestic programme.

This is so that Eskom can have the vendor use their real experience to manage the construction of earlier plants and can learn from them and avoid those first-of-a-class problems that can be so expensive (as Eskom learnt from Medupi unit 6).

Eskom does not want to be anybody’s guinea pig for new ideas. Koko is Eskom’s group executive for generation

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