20.05.2022

The future of nuclear power


In the foreground of the picture is a white inscription “nuclear energy” against a blue background. The text is inscribed into a hexagon. In the background, in a mirror reflection, a person in a blue suit, white shirt, and navy blue tie is pointing their finger to the hexagon.

Photo by Dreamstime

‘Nuclear power buys us a lot of time to develop other technologies. These can include the renewables or energy storage, as well as the implementation of fast reactors that will allow us to close the fuel cycle. Perhaps one of these days, sooner or later, we’ll be able to use nuclear fusion. However, the “days” that I’m talking about are so distant that, ultimately, our grandchildren will be dealing with developing technologies to replace the atom’, says Paweł Gajda, DSc from the Faculty of Energy and Fuels.

Read the second part of the talk with the expert in nuclear power. Find the first part here.

Let’s take a trip to countries which are shutting down their nuclear power plants. What does it look like, technically speaking?

At first, they turn off the reactor. This is a standard procedure every year, year and a half, when the fuel rods are replaced. The entire unit must be turned off because we want the reactor to be in cool shutdown so that it cools down enough to replace the rods. In the case of permanent shutdown, the procedure is analogous, but without loading up fresh fuel rods. When the fuel is removed, we can gradually begin decommissioning the power plant. The process is very similar to the shutdown of all industrial plants. However, we must keep in mind that a portion of the structural components may contain trace amounts of radioactive materials, such as the reactor pressure vessel (RPV) or other elements near the reactor. They are treated as low-level radioactive waste, which must be dealt with accordingly. Therefore, dismantling of the power plant usually starts with conventional parts.

The process is usually spread over time and takes a significant portion thereof. Of course, all this could be done faster, but the activity of the radioactive material decreases with time. This is why it’s worth the wait because the doses of radiation are smaller and people can work on site, instead of remotely. Moreover, this strategy also has an economic justification. The prolonged process provides constant employment, albeit not for a significant amount of people. As a result, the perspective of employment for someone dismantling a power plant may be 20 years even.

The components of the nuclear part are dismantled at the last moment, and some of those, such as low-level waste, are transported to radioactive cemeteries. These include elements that could be activated or contaminated, such as the RPV, steam generators, or other components that could have had contact with the fuel, e.g., containment liners. Given the large scale of its nuclear programme, France has been preparing a special containment for high-volume elements, where they could be stored before being recycled.

Is there an ideal example of an area that was successfully reclaimed after the decommission of a nuclear power plant?

There are examples of power plants that had been reduced to the so-called greenfield status. In the United States alone there are a few. Take, for instance, the Maine Yankee or Connecticut Yankee power plants.

Storage and recycling of spent fuel

As far as spent fuel from operating nuclear power plants is concerned: Are we doomed to store it indefinitely?

In this case, we have two options. One of them is to treat the spent fuel as waste in its entirety. In this scenario, there’s always going to be the need to build high-level radioactive cemeteries. There’s often this comparison to uranium ore, which is radioactive but occurs naturally. Therefore, if the radiation levels of the spent fuel reach similar values, we can assume that it is no longer harmful, which takes roughly 200,000 years. The number might seem a very long time from the viewpoint of our civilisation, but geologically speaking, where we discuss processes that take millions of years, 200,000 years feels like the day before yesterday.

On that note, there’s a highly interesting case – a natural reactor in Oklo, Gabon. This was a place with rich reservoirs of uranium ore. Due to the leaking water that flowed through it, a natural reactor was created, in which fission occurred on its own. This reactor is also an interesting case, because we have natural deposits of spent fuel there. This allows us to observe that the radioactive substances coming therefrom migrate in a limited capacity. And this place had not been properly sealed, even if we’re talking simple metal containment. In Finland, they are currently building a cemetery where fuel assemblies will be stored in sealed copper containers and buried 500 metres underground in granite formations. The construction of an analogous place is scheduled to begin soon in Sweden.

Bear in mind that spent fuel doesn’t go to the cemetery immediately; at first, it’s stored directly near the reactor, submerged in water that absorbs the heat and acts as a barrier against the radiation. Subsequently, the fuel goes to a dry storage facility. Such objects are usually located on the premises of the power plant; common storage facilities away from the power plant are rare. This is not a permanent solution, but it provides ongoing control over the waste, which can safely await further stages.

The photo shows cylindrical silver containers for radioactive waste. A black symbol of radioactivity against a yellow background is on the containers.‘Storing spent fuel near the power plant is not a permanent solution, but it provides ongoing control over the waste’, says Paweł Gajda, DSc; photo by Dreamstime

What’s the second option?

An alternative might be to reprocess this fuel. In some countries, this is already done on an industrial scale; France, for example, recycles plutonium from nuclear fuel and reuses it to produce energy. As the spent fuel contains mostly unused uranium, provided that we don’t have to store it, the waste mass is reduced about 30 times. The time required also decreases to several dozen thousands of years. However, if we were able to use all actinides, reaching the state of a closed fuel cycle, we would only have to store the products of fission. Then, after merely hundreds of years, their activity would be reduced to safe levels.

Which of the two variants is better?

It’s difficult to say unequivocally. Reprocessing has many advantages, but today, recycled fuel today is still more expensive than that made from fresh uranium. Therefore, it seems best to store spent fuel in containers above ground and wait to see which path proves to be optimal. We have the necessary technology to build a final cemetery and the decision to build it is purely political. That is why the decision on the ultimate fate of the fuel is often postponed.

New technologies in nuclear power

I’d like to ask you about innovation in nuclear power. Is there a nuclear Holy Grail that would increase the efficiency of such power plants?

There is nuclear fusion, which has been investigated for decades but still remains beyond our reach. However, there are smaller grails. Nuclear power likes tested solutions. The fact that water reactors are the most common stems from their uncomplicated structure. However, for other types, even if only one was constructed, we have plenty. Nevertheless, these technologies didn’t catch on well because they turned out to be less reliable in terms of operation time or availability – in this case, we can talk about fast reactors and its variants. There are considerably more other ideas; there are discussions on molten salt fast reactors. Thorium is also taken into account in nuclear power.

There are more prospective technologies at various stages of readiness levels. Twenty years ago, in various media coverages, they were presented as a revolution, but we are still waiting for it to happen. In the case of this sector, I would expect an evolution rather than a revolution.

To what extent do the research projects carried out at the AGH UST subscribe to this process?

Our team deals mostly with neutronic calculations, that is, we study the fission reaction in various types of reactors. In recent years, we’ve been carrying out calculations related to the development of fast reactors, accelerator-driven systems, or high-temperature reactors. These calculations are useful for optimisation both of the reactor design as well as the fuel cycle. Moreover, we are focused on developing and validating computational codes that can be later used to design reactors or assess their safety. It means that we’re not creating a ready-to-implement innovation for power plants, but rather providing tools that can be later used to develop new technological solutions.

Are there other applications for nuclear power plants than power production?

As someone has accurately said, nuclear power wasn’t a breakthrough in terms of electricity production. It has been a breakthrough, though, in terms of boiling water to do it [laughter].

A reactor is predominantly a heat source that we can try and use in a number of ways. A tested solution is cogeneration, that is, building a nuclear heat and power plant. Reactors can be used to produce heat for city heating systems, but also for industrial processes, which need a temperature that doesn’t exceed 200 degrees Celsius. This solution can be easily implemented in fairly all nuclear units; however, this is not something common worldwide.

We need more advanced solutions to produce heat for various types of industrial processes, such as synthetic fuel production or hydrogen production which is being discussed in the context of balancing the power industry. To this end, research has been conducted related to the development of high-temperature reactors. The thing is that we want to be able to power processes that require higher temperatures than those achievable in water reactors that are used to produce electricity. We’re talking temperatures reaching up to 1,000 degrees Celsius, even higher in the future. For this, we will need new technologies, that is, high-temperature gas-cooled reactors (HTGRs). Currently, we are part of a project related to the development of such units; we’ve also participated in other similar ones earlier. However, these are not reactors for commercial use and won’t become so any time soon.

Application for small modular reactors

What about small modular reactors (SMRs)?

It depends on when they’ll be commercially available and how much it will cost to actually build them. First such units are already operational, such as the Russian floating nuclear power plant Akademik Lomonosov or the recently commissioned HTR-PM high-temperature reactor in China, which was built to produce heat for industry. However, if we’re talking projects that are moments away from commercialisation, there’s one thing we should mention. When, more or less 20 years ago, the subject of small reactors was once again gaining momentum, there was a plethora of various concepts. However, the majority never even got past the stage of a Power Point presentation. The ones that did manage to push through are rather scarce. And if we are talking commercial projects, until now, no one has begun to construct a plant based on such reactors.

The photo shows a white side of a ship, which has horizontal red and navy blue stripes. There’s an inscription there that says “Akademik Lomonosov” in cyrillic script and an inscription that says “Rosatom” in Latin alphabet.‘First small modular reactors are already operational, such as the Russian floating nuclear power plant “Akademik Lomonosov”’, says Paweł Gajda, DSc, photo by Elena Dider Creative Commons Attribution-Share Alike 4.0 International

Despite all that, there are some hopes for such reactors in Poland.

A portion of industry does show interest in this technology. The KGHM company cooperates with the American NuScale company in this area. It’s been developing a 77 MWe small-power reactor, whereas traditional reactors often exceed 1 GW. The first power plant of this type is to be built in Idaho. At the moment, the formal assessment of the location has been concluded, and soon the company should file for a building permit. The launch of this power plant is currently scheduled for 2030. Another advanced project is the BWRX-300 by General Electric Hitachi, which I would gladly work on at my Synthos in cooperation with Orlen. It has a power of 300 MW, which is almost as much as many coal power plants that currently operate in Poland. Furthermore, British Rolls-Royce talks about a reactor with 460 MW, which begins to blur the boundary between “large” and “small” reactors. Besides, even the NuScale one, in terms of size, is not that small as you could imagine. In this case, the reactor was fused with a steam generator into one big element. As a result, the whole thing has a mass similar to a pressure vessel of a traditional reactor.

Why did KGHM or Orlen and Synthos become interested in small reactors? The reason is that the possibility of buying reactors with smaller powers makes it financially feasible for those companies. From their points of view, this could be profitable, as they’ll need a zero-emission and constant power source at the same time. In both scenarios, both the construction time and its costs remain unknown. Bear in mind that you should always anticipate delays and going over budget in the case of prototypes. We’ve witnessed it with the construction of so many large power plants in the last few years. In the case of SMRs, there had not yet been any construction projects, so a number of surprises can emerge during their implementation. Whether companies should take such risks is strictly a business decision. I root for them, though. The more technologies to choose from, the more possibilities.

Will SMRs get the chance to find application in the public domain?

They can be a good complement to larger units. Not all loci are suitable for large power plants. If we’re talking about building two units, 1.5 GW each, we end up with 3 GW. We’d have to make sure that these are cooled properly. So there will be places where we should consider not 2x1.5 GW but, for instance, 4x300 MW. Especially that proper distribution can be beneficial if we want to use reactors in cogeneration. It’s definitely harder to absorb all the heat generated in one place by a 4.5 GW power plant.

The eclipse of atom?

What will happen to nuclear power after the energy transformation?

I am convinced that nuclear power is not as transitional a solution as many people think. If you ask me about the Polish nuclear power programme, that is, building large units – the first one is scheduled to start in 2033. The subsequent ones are to be built every two years, with the last one commissioned in 2043. The reactors are planned for 60 years of operation, so, even without the possible life extension, we’re landing in 2103. This is nothing else than the 22nd century! The number of things that can change in this time is huge.

Nuclear power buys us a lot of time to develop other technologies. These can include the renewables or energy storage, as well as the implementation of fast reactors that will allow us to close the fuel cycle. Perhaps one of these days, sooner or later, we’ll be able to use nuclear fusion. However, the “days” that I’m talking about are so distant that, ultimately, our grandchildren will be dealing with developing technologies to replace the atom.

So your students won’t end up unemployed?

I hope not. It’ll depend on the political will to see the programme through. If we consider the issue of climate, there’s no other way. It’s not a question of “do” we need nuclear power, but rather “how much” of it we will need.

In the first part of this interview, to be found here, we’ve discussed nuclear power in the context of energy security and the EU climate policy.

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Paweł Gajda, DSc, was interviewed by Piotr Włodarczyk from the AGH UST Centre for Communication and Marketing.