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Interview: Eskom’s chief nuclear officer on renewed interest in the Pebble Bed Modular Reactor

Interview: Eskom’s chief nuclear officer on renewed interest in the Pebble Bed Modular Reactor

Eskom’s chief nuclear officer, David Nicholls, explains the potential of the utility’s renewed interest in the Pebble Bed Modular Reactor (PBMR). The project is still in its research phase. CHRIS YELLAND and PIERRE POTGIETER interviewed him for EE Publishers. This is an edited version.

What is Eskom’s new vision for the previously abandoned Pebble Bed Modular Reactor (PBMR) project, and how did this new vision come about?

The new vision is very similar to the old vision. It’s looking whether there’s a market and potential for ultra-safe, small, nuclear reactors for power generation, using high-temperature technology. When Brian Molefe came into Eskom he reviewed what Eskom had stopped doing over the last few years, and asked why we had closed the PBMR project down. In his view, it was neither for technical nor commercial reasons, but a mixture of many other things. We were asked to look at the project again to see if there was a better solution. We’ve started again with a clean sheet – a paper study with limited research funding going into it. It’s more emotion than money at the moment. We’re looking at a much simpler and much more efficient plant than we had the last time round.

Since the first PBMR project in South Africa was abandoned in 2010, is there still a window of opportunity for the development and commercialisation of small modular nuclear reactors by Eskom for South Africa and the global market?

I think there’s a window of opportunity still there. In some way initiated by the former PBMR project in South Africa, many studies have looked into small nuclear reactors, and they conclude that power generation reactors of 150 MW or so could be commercially viable – which no one had thought previously possible. But no one has yet filled that window. We certainly haven’t seen a competitor in the marketplace that has filled the hole that PBMR was trying to fill. And there is much interest once you get to the stage of building the first couple of machines – certainly in the African market, and certainly for the small grid. It would also fit in terms of load-following for a grid with a large amount of renewable, intermittent generation.

Would these small modular nuclear reactors for power generation be a factory-built kind of product, or site-built, or a combination of the two?

There are always site activities, but basically the smaller and more compact the machine gets, the more factory manufacturing becomes possible. Our view would be that you could apply factory manufacturing to most of the components we’re looking at. One cannot do concrete and civil construction things in the factory, but I think the idea of a mass-produced factory-built machine is exactly where the PBMR is moving. You atomise the engineering cost, you atomise the design costs, and you atomise the skill-set of the people building it.

Would the new PRBR simply be a resuscitation and continuation of the previous PBMR project, or would there be any significant technical or other differences/ improvements?

This new project is not simply a resuscitation of the PBMR project, it’s based upon the PBMR technology and what we learned doing that. At the moment it’s sort of lab-scale research work with minor engineering, and it will stay that way for some time to come. But yes, it looks at taking advantage of what’s happened in the last 30 years. The PBMR was fundamentally designed in South Africa in the 1990s, based on German technology that was demonstrated in the 1970s and 80s. The new work we’re doing now has been looking at what has changed since then, and how we can change the PBMR design to take advantage of this. Probably the best example is 3D printing. We can now consider 3D printing the ceramic materials, which would have been unthinkable 20 years ago. We are also considering the use of concrete pressure vessels instead of steel, which could reduce the price significantly.

The fuel would essentially be the same as was produced for the previous PBMR project in South Africa. But based on tests conducted in the USA, we know that for our fuel, the upper design limit of 1,600°C for the German fuel can now be increased beyond 1,800°C, and possibly as high as 2,000°C, which pushes the reactor envelope significantly further.

Do you envisage that the further development, piloting, commercialisation, licencing and construction of the new PBMR would be done directly by Eskom, as opposed to funding by the South African government, external shareholders and additional Eskom debt?

You’re asking me the question probably a year or two too early. We’re still looking at the research, and conceptualising a proof-of-concept machine. We’ll first have to come through this research phase, assuming we get results we that we like, before we come up with a proposal on what the costs would be, and how to go forward on these costs. That’s a choice we’ll make at that time. At the moment it’s being funded from Eskom’s pre-allocated research budget.

In the new vision, does Eskom have a clear idea of the cost of developing, commercialising and construction of the new PBMR?

At this stage we’re doing research. What will come out of this in future is a view of the cost to develop the design, the cost of a proof-of-concept machine, and the potential cost of a commercial machine. We will then have to look at the business case that goes with this. We’ve got very limited funds at present, and we’re doing investigations before going back to our principal and shareholder, the government, to ask them for approval for any outcomes proposed. So at the moment we’re trying to conduct a proper research process of what is possible, not based upon what was or what could be done in the past, but what can be done now and in the future.

This time round, what would be the envisaged time-scale for deployment of PBMRs in South Africa, where would you deploy them, and for what purpose?

The last PBMR was meant to take a pre-existing German commercial package, rearrange it, and put it in the marketplace. That was to be quite a quick process. This time, we are looking more at a research project. We are looking at having a proof-of-concept machine, i.e. a research machine, running by the mid-2020s, if all goes well. And then potentially starting a commercial machine roll-out starting 10 years after that.

From about 2027 onwards, the need for base-load capacity becomes quite urgent if we assume we are going to have any kind of economic growth, and that we will have to decommission several of Eskom’s coal stations. In our view, this need for base-load capacity will probably be met by building large pressurised water reactors (PWRs). Then some ten years after that, when the famous 9.6 MW nuclear new-build has been done, we could possibly be looking at doing PBMRs.

As to why and where to deploy them – look, Eskom is a power generation business. That’s why we’re gearing up the concept. To this end, the PBMR will be seen as potentially replacing some of the current coal fleet. If you look at the 2030s – you look at possibly replacing old coal stations with high-temperature PBMR reactors deployed on the old coal-station sites.

To ensure some level of certainty, would Eskom commit upfront to purchase say the first 10 such PBMRs, as Eskom initially did previously before it subsequently withdrew such commitment?

It’s way, way too early to ask that question. I haven’t got a clue. Ask my successor, or my successor’s successor, that question. I’ll be retired by then!

To meet this vision, does Eskom have the necessary deep pockets and nuclear design capability, and does SA have the necessary depth of nuclear engineering capacity and experience?

I think, to answer that question very simply – in terms of deep pockets: no comment. We’ve discussed money already, and we haven’t got a clue yet. But I think you’ll be surprised how much depth Eskom and the country has in terms of engineering. In this particular technology, namely high-temperature nuclear reactors, we were the world leaders by a good margin. And most people are still around. It’s interesting how many of them now work on other projects in the USA and elsewhere, based on their work in South Africa. And I think the answer to the question is that we didn’t have a problem with resources on the previous PBMR project. Personally, I don’t believe that if this goes into a serious engineering phase we’ll have a particular shortfall. My experience is that you create engineers by doing things, not by doing studies.

Is it really Eskom’s role as a public electricity utility to involve itself in the design, engineering, piloting, commercialisation and construction of PBMRs in SA and globally as a nuclear technology developer and EPC contractor?

All business is in the business of taking risks. To the first question of should we be in the business of an EPC contractor, the answer is: we did it in the past, and in my view, it’s a central theme in a company like Eskom. We continue to build transmission lines, we continue to be an integrator of these technologies. Should we be in the design-engineer-commercialisation experts? – I don’t know, and I don’t know how this will play out. We’re looking at technology options, and we’re looking at some of the techniques to manufacture them. How it will be rolled out if it works, I don’t know. It could be through a PMBR company created for this specific purpose. In fact, there are successful utilities around the world, a lot of them with own engineering, procurement and construction activities. Eskom used to do this big-time, and successfully, in the 1980s.

What did Eskom learn from its previous diversification forays through Eskom Enterprises and PBMR (Pty) Ltd?

I’m not sure what Eskom learned, but I’ll give a couple of answers from my perspective.

Firstly, start slowly; don’t leap into something with both feet, thinking you understand the whole marketplace; work up to it; make your decision wisely; but once you’ve made the decision, don’t stop halfway through. If you put this in the context of the PBMR, you’ve got to think where this takes you.

Secondly, get management engagement. That’s what is so exciting about this project from the beginning. Mr Molefe did his homework, he did his research, and he said: “Given this research, please can you do this for us.”

In this case we said very clearly that we’re not just going to leap into another PBMR project; we’re looking at the technologies; we’re having a technology discussion. Technology leads to engineering, which leads to money. Not money as in spending money, but money as in: “If I’m going to build a concrete pressure vessel, how big will it be and at what cost?”

Are we going to build PBMRs? I have no idea. But I do know that we will end up with a bill of materials for the theoretical plant to indicate whether we can afford it or not. DM

Photo: Eskom’s chief nuclear officer, David Nicholls (EE Publishers)


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