Water-cooled reactor technologies are boring. There, I said it. After all, the steam engine was invented in the 18th century and your typical water-cooled reactor is essentially just a glorified example of this, albeit with a nuclear heat source and an electric generator. An even simpler analogy, often provided to younger students, is that a nuclear reactor is like a giant kettle. Granted, the nuclear plant is generating useful energy instead of consuming it, but the basics are the same. As the old saying goes, nuclear plants are a complex way to boil water.
No one habitually catches steam trains these days and it must appear anachronistic to outsiders that we still depend on steam for electricity generation. With the exception of certain enthusiasts, most people just don’t get excited by steam anymore.
Given the perpetual buzz around new technologies, most notably AI at the moment, it does seem that the arrow of progress points in one direction. The old and established ways of doing things are inevitably destined for the dustbin of history – making way for shinier ‘advanced’ alternatives.
Those with a casual interest in the nuclear sector will be drawn to future technology. They will likely be dazzled by the potential of fast reactors, molten salt, high temperature, thorium and even fusion reactors – all of which tantalizingly promise numerous advantages over the antiquated water-cooled and moderated reactors of today.
This is an exciting story filled with feisty start-up ‘heroes’ and big transformative visions. It’s no small part of the reason why public attitudes towards nuclear energy have been improving. According to the mainstream media narrative, old nuclear is slow, expensive and prone to fault – if not downright dangerous. By contrast new ‘advanced’ reactors are none of these things.
Inside the nuclear industry it’s a different story. Boring is in fact generally a good thing. Boring is predictable and safe. Boring means turning up to work and enjoying another day of uninterrupted production with all the gauges in the green and zero injuries to report. Boring is being able to meet your contract obligations, keep your customers happy and make a reasonable profit.
At the present time, large utilities and operators are the main customers for nuclear reactors and they are the ones that will chiefly determine which new nuclear technologies get built in the future. It is clear that most utilities would prefer to stick with what they know, and what they know is light water reactors – pressurised water reactors (PWRs) and boiling water reactors (BWRs). In a few notable exceptions, such as India and Romania, the preference is for pressurised heavy water reactors (PHWRs).
The age of the large, water-cooled water moderated reactor is far from over. Indeed, there appears to be no end in sight.
Small modular reactors (SMRs) are gaining traction and a number of countries are moving to deploy these, with some intending SMRs to be the first and only class of nuclear technology installed on their grid. But here again the water-cooled designs are set to dominate the near-term market, and possibly over the longer term as well.
Observing the market ‘leaders’, we see that Russia’s land-based SMR is a variant of a PWR deployed in its icebreakers. It is true that China has recently constructed some high-temperature reactors which are technically SMRs, but the industrial focus has now shifted to the 100 MW PWR which is under construction in Hainan. South Korea is now championing the i-SMR and, no surprises, it too is a PWR.
The sole SMR design currently certified in the USA is a PWR (NuScale VOYGR), while the North American SMR project closes to actually beginning construction is a BWR (GE Hitachi’s BWRX-300 in Darlington Ontario). Where the US-state is supporting vendors competing for overseas projects it appears to be chiefly promoting either of these two designs.
For France it is the Nuward design, yet another PWR. Recent news is that, following discussion with utility customers, the Nuward developers have decided to redesign their reactor with a focus on proven components rather than innovation. About as perfect a confirmation of this thesis as could be wished for.
Another confirmation comes from the advanced nuclear space itself, and one start-up company which read the tea-leaves and decided to switch from pursuing reactor development to offering reprocessing as a service for light water reactor owners.
This ongoing dominance of water-cooled reactors globally should not come as a surprise. These technologies have already been proven capable of operating safely and reliably for greater than 50-year spans. For the companies which must live with their choice of asset over the long-term, this track-record matters a lot. Truly these are remarkable machines.
Above and beyond this proven capability, there is a pragmatic inertia to the water-cooled reactor technologies and a supporting ecosystem which the advanced reactor vendors may not be able to match for decades – including in fuel/component supply chains, exchange of safety information, skilled workers, regulation, and so forth.
Pragmatic considerations also override concerns utilities may have about recent construction performance and cost over-runs. While it is true that much of the recent construction experience with light water reactors has been poor, especially in Western countries, there is currently no evidence to show that advanced reactors will have an easier time with this. True first-of-a-kinds are expected to be harder still to construct, and few utilities are willing to act as guinea pigs and take on the first-mover risks.
If the vendors of exotic reactor technologies are going to be hard-pressed to win utilities over, it seems unlikely that they will have an easier time with other new potential customers such as the chemical sector and data centre operators. One might assume that these new operators will seek to follow the lead of their more experienced cousins. We will have to wait and see.
For the record, this is not a statement of reactor technology preference. It’s simply a reflection on the trajectory the global industry now finds itself on. Advanced nuclear reactor technologies promise to create a better version of the nuclear industry – something more economic, safe, sustainable and flexible – but how on Earth do we get there?
In most places the nuclear sector is not a monolithic integrated combine following an ideal path determined by an inner council of scientific elites with the risks and benefits socialised by all. Rather it is a commercial enterprise, comprised of various companies with their own unique interests and business strategies.
If a profound nuclear technology transition is ever to happen then clearly there is a huge role for government to play. And for the advanced reactor and fuel cycle projects which are currently moving ahead, government is clearly the driving force. For example, the Terrapower fast reactor project in Wyoming is being made possible because of the Advanced Reactor Demonstration Project programme and cost-sharing arrangements. But this piece-meal support for demonstration projects seems far from enough to engineer a total reactor technology paradigm shift.
Of all the efforts to fully close the fuel cycle and evolve the nuclear sector, the Russian effort seems the most likely to succeed. Here there is indeed a national nuclear champion integrated across the fuel cycle and what appears to be an accepted technocratic culture. Maybe the same could be said for China and India. But, even in these countries with a clear long-term vision and apparent alignment between government, research bodies and industry, there is no certainty of success. Technology demonstration does not progress by fiat. There is nothing inevitable about an advanced reactor future.
It seems that the rest of the world is faced with a water-cooled reactor future, with a handful of exotic variants on the side. The timescale for this to change appears to be longer than most of us will live. Given how extraordinary water-cooled technologies have proven to be this is far from a bad thing. However, we’d best get good at building them again and we might want to reignite some public enthusiasm for steam.
