What should the UK do with its nuclear waste?

The Sellafield nuclear site in Cumbria is the temporary home to the vast majority of the UK’s radioactive nuclear waste. This is the byproduct of nuclear fission: splitting apart the nuclei of heavy elements like uranium and the collecting the energy this releases. But what to do with the radioactive nuclear waste, which can be detrimental to the environment if it isn’t managed properly and can remain hazardous for 100,000 years, is key to its potential future in the UK’s net zero ambitions. Now, concerns have been raised about the safety of the Sellafield site, with the BBC reporting leaking silos and sub-standard cybersecurity. To find out more, I’ve been speaking with Claire Corkhill, a professor of mineralogy and radioactive waste management at the University of Bristol. Claire recently contributed to a BBC article about Sellafield and the UK’s nuclear waste…

Claire - All nuclear waste starts as uranium from nuclear reactors. So this uranium is what has been used to generate energy from the splitting of uranium atoms. What that does is it creates what we call fission products. These are smaller atoms that are unstable and they emit radioactivity. And this radioactivity is what makes the nuclear waste so very hazardous. A lot of people's minds will automatically go to The Simpsons and that green glowing goo that oozes out of barrels around Homer Simpson. But actually it's much more boring than that, I'm afraid to say. Physically speaking, radioactive waste is contained in ceramic materials, in glasses and also in cement. And when I say glasses, what I mean is it's not poured into containers of glasses. It's actually chemically locked up inside the structure of the glass.

Chris - And is it all solid stuff or do we end up with liquids as well?

Claire - Well, it is a mixture. In an ideal world, when everything's working correctly, we have solids, but that hasn't always been the case in the past. So almost all of our waste is stored at the Sellafield site up in Cumbia. Now, some nuclear power stations that are being decommissioned around the country, for example Trawsfynydd and Wylfa in Wales, these have temporary stores, interim stores. But the majority of the waste is at Sellafield. And the majority of it is in safe, secure warehouses essentially, where the waste is stacked up in barrels or drums very neatly. It looks a bit like an Amazon warehouse, but obviously with less people driving around. But some of it has been there for the last 50 years or so, underwater in what look a little bit like large swimming pools, and some of these large swimming pools are exposed to the air, which means it's exposed to all of the elements. It's exposed to birds swimming in it and so on.

Chris - Obviously exposed to the elements and those kinds of constraints, that's not ideal. But once it's in that solid vitrified or concrete like form, is that not okay? Can we not just bury that for example, and then leave it to cook for a few hundred thousand years, just avoiding the area and it will become safe?

Claire - Yeah, that's really the idea. So the radioactivity of the concreted waste is kind of the medium level of activity, if you like. So we are okay with storing that in these warehouses over long periods of time. And we're talking here about decades now. Occasionally you'll need to refurbish the packages if they've started to degrade and so on. It's the higher lived radioactive waste that we're a little bit more concerned about because this is really hazardous to biological life. It's emitting an awful lot of heat, so it needs human intervention to try and keep it cool. Now that's okay whilst we have the technological world that we live in today, but the radioactivity of these wastes will persist for hundreds of thousands of years. So how can we guarantee right now that people in 500 years time or 1000 years time will have the technology to be able to keep these wastes cool? Ideally what we really want to do is take all of these materials away from people forever and isolate them from populations so that we don't have to rely on the populations of the future to try and keep this material safe. And as you quite rightly suggested, one of the best options for this is burial in a deep geological disposal facility.

Chris - Do we have something like that? I mean, is there anything on that site that could accommodate that? I suspect that doesn't go down very well with people who are concerned about the environment or people who have to live near where you intend to do that.

Claire - So the first thing to say: it's important that other countries are already building these types of facilities. So Finland are already well advanced with building their facility. They've not started accepting waste yet, but they will in the next few years. In the UK we have a policy that the government has correctly identified that we can't just keep generating waste and storing it for very long time periods at Sellafield. We need to do something safer with it in the future. And what we are looking for are two things. The first is a site with a suitable geology, and the second is a site that has a willing community. So we are looking for communities to volunteer to have one of these facilities. And you might think that, well, who would volunteer for this? But, actually when you look at the Finnish example, there were communities who were fighting over the facility because they wanted all of the financial benefits that would come from having construction and the financial incentives from the government to have that facility in their local area.

Chris - And these facilities that we are talking about, next generation storage facilities. Is that going to be future proof not just from the perspective that someone in the future won't have to worry about dealing with it, but the sorts of waste we anticipate the next generation of nuclear producing. Because there's a lot of talk about, for instance, SMRs, small modular reactors, being used in various places. Will the sorts of waste we anticipate coming out of those sorts of facilities be able to go into the waste facilities that we are planning today? Or are we going to be back to square one in a few years time because we generate waste and say, 'well, these are not fit for purpose.'

Claire - What we can say is that small modular reactors produce the same types of waste as the large reactors that we're currently building and operating in the UK. So like Hinkley point C that's currently being constructed. We're not worried about those. That waste will be able to go into a geological disposal facility. We're fairly certain of that. The other types of more advanced reactors we're talking about are things like fast breeder reactors and molten salt reactors. These things are a little bit more experimental on paper at the moment. Now is the time for us to really be looking at those designs and thinking about what the waste will look like. We can then start to understand whether the geological disposal facility will be suitable. That's still a question that we haven't got an answer to. And it's something that the people who are designing these reactors, it's something that they really need to have at the forefront of their mind. Because if we take into account waste now at this early stage of design, we could avoid those problems of the past that had us pile waste at Sellafield in not the best way. It's a very timely question and it's something that I hope we can really get to the bottom of before anyone starts to build any of these new nuclear reactors.