Are we ready for the next Chernobyl?

A look at bioremediation and how microbes may help us clean up nuclear waste.
01 August 2017

Interview with 

Iryna Mikheenko, Lynne Macaskie & Joe Hriljac, University of Birmingham


Image of nuclear power station on a sunny day


The nuclear reactor meltdown at Chernobyl may eventually cause over 40,000 deaths through cancer, and the area is still uninhabitable. Nuclear power is still used around the world, but what do we do the next time the worst happens? Graihagh Jackson has been investigating an idea called 'bioremediation', the use of nature to clean up spills or contamination. So could microbes be used to help with a nuclear clean-up, and will it be enough to keep us safe? First, a look back at 31 years ago to Chernobyl.

Graihagh - In March 2011, a major earthquake off the coast of Japan sent a 15 metre high tsunami surging into the nuclear power facility at Fukushima disabling the power supplies and cooling systems. Three reactors rapidly went into meltdown and subsequent explosions released significant quantities of radioactive material into the water and atmosphere - enough to be graded a level 7 on the international nuclear and radiological event scale. There is no level 8 - this is as bad as it gets!

This wasn’t the first accident of its kind and, sadly, it won’t be the last. Thankfully, science can help with the aftermath.

I’m Graihagh Jackson and in this programme I’m finding out about new breakthroughs to help clean up when nuclear disasters strike…

Like Fukushima, the Chernobyl nuclear power station in Ukraine, part of the former soviet Union, also went into meltdown in 1986 and it too got a grade 7 on the international nuclear and radiological events scale. An explosion caused a 9 day long fire to eject radioactive material into the atmosphere and, over 30 years on, experts still can’t agree on how many it killed.

What we do know is that two people died immediately as a result of the blast and another 29 died in hospital over the next few days. The harder bit is quantifying the long term effects. A paper in the Journal of International Cancer predicts that by 2065, 41,000 people will have died of cancer.

Lyn - When the Chernobyl accident happened we realised that this was a serious discharge and these elements were getting put into the environment. And, it was only a matter of time, to my thinking, that another accident would happen sometime one day.

Joe - As a standard part of the nuclear fission process, you develop lots of radionuclides…

Graihagh - Joe Hilltrek and Lynne Macaskie, both from the University of Birmingham. Joe looks at these radionuclides, these are just radioactive atoms…

Joe - Some of those are relatively insoluble, they won’t travel very far in the environment, etc. Others form water soluble salts and those, in particular, are more difficult to target because they dissolve into groundwater, they move away from the site, etc.

Graihagh - I suppose the thing being water soluble is that if they are water soluble that means they can move into our food chain and our water sources?

Joe - Yeah, so potentially they can. If you look at strontium, it’s chemistry is very similar to the element calcium, and calcium phosphate is what makes your bones and teeth. So, if your body ingests strontium, there’s a chance that that can get into your bones and things. Cesium, it mimics another element called potassium, which is very important to the body for neurological functions. So these sorts of elements, as they get into your body, will cause you serious health problems.

Graihagh - When Joe says serious health problems, he means cancer. After Fukushima, many governments cut back on their nuclear programme but, five years later, it seems as though nuclear is back on the agenda because of its status as one of the few reliable and low carbon power sources. It’s hard to find statistics, but said there are 245 reactors worldwide, with a further 60 currently under construction which means it’s likely that there will be another nuclear accident.

The question is: can we manage it quickly, safely, and effectively? That’s the question I’m hoping to answer today. First though, back to Chernobyl…

Irina - My name is Irina Mashenka.

Graihagh - Irina Mashenka was living in what was then the Ukrainian Soviet Socialist Republic and remember that Chernobyl nuclear facility was a big deal back then. A huge source of national pride and, as a result, it attracted lots of young people to work there.

Irina - Chernobyl station was a really, at that time, state of the art. It was very exciting to work on an atomic station which could provide electricity energy for huge territories. The city was very young, there were a lot of young kids and it was nice.

Graihagh - Until the 26th April, 1986…

Irina - What can I say. When it happened it was really something nobody could expect.

Graihagh - Irina was around 100 kilometres away and on maternity leave with her little daughter. That may sound far away but, actually, in two days the radiation had travelled 1,000 kilometres and set off alarms in another nuclear power plant in Sweden. 1,000 kilometres - this was actually what forced the Soviet Union to publically admit there had been an explosion. On the 28th April at 9pm a news programme read the following statement:-

There has been an accident at the Chernobyl nuclear power plant. One of the nuclear reactors was damaged. The effects of the accident are being commuted. Assistance has been provided for any affected people. An investigative commision has been set up.

Graihagh - As you can tell, there was very little information about what was going on. And remember, the internet wasn’t around and nobody knew what to do or what the risks were...

Irina - We didn’t know anything about scale, we just understand okay, radiation it’s something dangerous. It’s something you will not see, sniff, or experience in any way but, at the same time, it’s not harmless. Definitely the only solution is to get out of the contaminated zone but the explosion was so big, and the impact was so big, so it was not realistic for everybody.

Graihagh - Irina’s brother and sister-in-law were one of the young graduates who had moved to this site of national pride to work on Chernobyl power plant…

Irina - As I remember, my sister-in-law telling me they were happily wandering around the (11.09), they went on business, shopping, etc. After they were informed that evacuation would happen they just packed their things - two backpacks. It was so funny, my sister-in-law said “you know what, when we came we had two backpacks and that’s all. And now, several years on, I have the same two backpacks on, and two children. And that’s it we’re going the same way.”

Graihagh - Did they expect to be able to return and go back and continue their lives?

Irina - At first they thought everything will be sorted within a couple of weeks or so. But it turned out the scale of the disaster was too huge so they were not allowed to come back.

Graihagh - I know now people can go back and it’s a bit of a tourist destination to learn a bit more about it. I wonder, have you ever been back or considered going back?

Irina - I’ve never been back but my family, they went back I think several years ago. They went back and took a lot of pictures. They went to their flat and it was all dilapidated and ruined. A lot of streets are covered with growth. So it’s a ghost town effectively. They find it distressing. People didn’t really get enough help. And definitely later on the health problems developed. It’s not that immediate.  Those who got radio diseases etc, etc, they were helped immediately. But those who didn’t get acute poisoning were really neglected.

Unfortunately, to see the scale you need time. You need time because a lot of these things develop slowly, develop not that explicitly - it builds up. It’s really scary. My family are under medical surveillance for almost 30 years and once a year they have to go to the clinic.

Graihagh - I suppose, almost in some ways that waiting in fear that something might happen is a horrible thing to live with?

Irina - Yes. But, in reality, we humans somehow adapt to this situation and yes, in the background you have this nagging feeling that something can get wrong, but life is going on. And you are sticking to everyday life, you are doing things, you are here, you are involved in all sorts of things, and the point is to stay as positive as you can. We will do our best otherwise you can sit in a corner and cry all your life, so what’s the point.

I think we still need time to realise and understand as humankind how to deal with this.

Graihagh - It's heartening to hear Irina’s positive outlook on things. But, to me, it really highlights how important finding a solution to deal with this is…

Lynne - When the Chernobyl accident happened we realised that this was a serious discharge and these elements were getting put into the environment. And, it was only a matter of time, to my thinking, that another accident would happen sometime one day.

Graihagh - This is Lynne Macaskie from the University of Birmingham. It was Chernobyl that changed the course of Lynne’s research…

Lynne - We really wanted to pursue the research so that we had a possible solution sitting and waiting if that day should come.

Graihagh - And, sure enough, that day came 25 years later with Fukushima. Before all this though, Lynne was researching how you reverse metal contamination using a really cool concept called bioremediation…

Lynne - Bioremediation is a sort of global term where you’re using living creatures, or plants to clean up pollution or to decontaminate environments that have been contaminated by things that you might want to remove.

Graihagh - Things like harmful metals that we humans release into the environment be that cadmium, or lead, or even radioactive metals like uranium. Lynne doesn’t use a plant though - she uses microbes. But, to begin with, it was a lot of hard work isolating one microbe among hundreds...

Lynne - My brief when I turned up in the lab to start this project was that the chap that had started it, called Alistair Dean, had this idea in the mid 70s that you could use microbes to hoover up toxic metals. He got a grant to try to make this happen and he got as far as collecting hundreds of strains from the environment, from actual contaminated sites somewhere in the northwest. And he said “welcome Lynne, those are your bacteria. Go and develop a process.” So I spent about 18 months going through this collection one by one. It was was very painstaking but, eventually, we came up with one that worked.

Graihagh - What was this one called?

Lynne - It was originally classified professionally - this is the 1980s so we didn’t have molecular biology - it was called the citrobac, which is a very harmless microbe that comes in the soil. Then when molecular biology came along it got reclassified as a thing called cayratia. It’s a naturally occurring strain which means it’s had a chance to pick u p all sorts of genetic bits and pieces from the environment, which is how we think it evolved to be able to cope with life in a metal contaminated environment, and basically lock them up and drop them harmlessly.

Graihagh - Sounds a bit too good to be true doesn’t it? And weirdly the harmless substance that it locks the metal into is really similar to a mineral we all know very well… bone. So how does it do it? Well, this microbe produces an enzyme, basically a substance or catalyst that speeds up chemical reactions and then…

Lynne - … it takes one constituent of bone called phosphate. And then when a metal is around instead of using calcium, as you would make bones out of, it precipitates the toxic metal with phosphate and it locks it up into a solid which is analogous to what you would find in our bones. This worked beautifully well and we realised the bacteria’s function is just to make a mineral. They don’t care whether you’re taking up toxic metals or not. It’s actually this mineral, which is akin to bone, which is the material of interest because, by this stage, the bacteria don’t even have to be there because the material hoovers up radionuclides, and so you can kill bacteria and it’s perfectly safe to handle and to use.

Graihagh - And that’s because once the bacteria is gone the chemical reaction can’t reverse very easily. These toxic metals are reduced to a non-hazardous white powder…

Lynne - It’s as if you’d taken a bone and ground it up very finely.

Graihagh - But the microbes aren’t fussy. You don’t need to feed them uranium to make this hoovering substance. Lynne later found out that you can just use calcium...

Lynne - We don’t use uranium any more because we realised that you could do a very similar trick just using calcium, which is totally innocuous. Nowadays the bacteria are making calcium phosphate - it’s called hydroxyapatite. So that is actually the material that is used to accumulate radioactive materials from water.

Graihagh - The radioactive atoms can still be slurped up, but there’s an added benefit to using this hydroxyapatite, the calcium phosphate rather than plopping the microbe itself into the contaminated water. With hydroxyapatite you don’t need the enzymes and microbes anymore. Why is this better? Well, if you have a more acidic water, for instance, the enzymes don’t work very well. So you make it more robust and reliable because it can work in a larger number of environments. That said, you don’t just want to go chucking it all into contaminated water because, well, how do you collect it back up again?

Lynne - The bacteria are very smart when they’re growing. The produce a sticky substance which sticks them onto surfaces. If we can persuade them right, we can stick them onto sponges, and they grow and they make this surrounding environment just right for mineral to grow. So, actually, we’re making a spongy material with has got a layer of this bone substitute on it and that is an absolutely fantastic filtration material. But the benefit of bacteria is because you can grow them, you can make the material that you need, and the quantities that you need in a very short space of time. The advantage of this is that, effectively, you can deliver the material on demand and in an emergency you’re not going to have any notice that there’s going to be a demand, so it’s almost a rapid response.

Graihagh - Lynne had a concept and it didn’t just apply to nuclear accidents like Chernobyl and Fukushima. If ever there was a dirty bomb i.e. an explosive that contains nuclear material, this could be deployed. Lynne had, effectively, developed a weapon of her own - this hydroxyapatite And this is how Joe Hilltrek fits into the picture because you don’t just want one weapon against these sorts of emergencies, you want an arsenal of weapons…

Joe - If we have a library of materials, then we have much greater confidence that we can clean up not only the existing waste, but should there be another accident we can deploy materials right away and I thinks that’s very important. We have to make nuclear power as safe as possible, and I think knowing in advance there are materials present should there be an accident is a very important thing.

The materials that we use would either absorb those onto the surfaces, and bio-HA is one of those. It tends to be a surface absorption process.

Graihagh - Bio-HA is just another name for hydroxyapatite by the way. The bio meaning it’s produced by a biological process as opposed to a chemical one.

Joe - The other way chemically you can treat things is what’s known as ion exchange. Some elements like to give up electrons - electrons are negatively charged, so what you end up with is a cat-ion which is a positively charged species. Caesium and strontium fall into that category. Other elements prefer to take up electrons and become negatively charged. One of them, again, sometimes people need to deal with in terms of reactivity is iodide.

Graihagh - Joe has a material called zeolite. It’s a white powder and it locks up these positively charged atoms - the caesium and the strontium. Caesium and strontium are positively charged because they have more protons than electrons. Electrons are the negatively charged ones that whizz around the nucleus of the atom, and in the nucleus are the protons which are positively charged, and the neutrons which, as the name might suggest, are neutral. What Joe’s zeolite does is it shares its electrons with the caesium and strontium causing them to bind together. But that’s not all…

Joe - We attach small iron oxide particles to it; that provides the magnetism then.

Graihagh - You want magnetism because this exchange is reversible. It’s not stable and, therefore, the caesium and strontium can be re-released from the zeolite. However, if you magnetise the particle you can then separate the radioactive material from the water, How? Well you…

Joe - … pump the water through a tube that had very strong magnets round the outside that will trap the particles and you will just have pure water going through. The other thing you could do in theory, although in practice I’m not sure how you’d do this, is to sort of drag a magnet through to collect the particles afterwards. That, I think, is a wonderful concept but I’m not an expert on magnetism. I don’t know how strong magnets you’d need to be able to do that. But, ultimately, that would be the most wonderful thing wouldn’t it? That you disperse these in harbour  and then you drag a magnet through and all the particles with radioactivity just get taken onto your magnet.

Graihagh - Once you managed to get these soluble species out of the water column, out of whatever’s contaminated, what happens next to that because I imagine you don’t really want that kicking around for much longer either out in the open?

Joe - Exactly. The traditional route is to put it in a steel drum and put it in a lot of cement. The cement will both give you a non-soluble barrier if you like, plus it’s in a steel drum, so that’s considered one method of long term storage. The downside of that is you’ve increased the volume of your waste now because - I don’t know the exact ratio - but it might be one part zeolite to ten parts cement. So you’ve multiplied up the amount of waste you have to worry about for the longer term.

Another thing you can think about is to thermally break down your material into something that’s got a higher density, so there’s less of it that better chemically bonds the species within it. We also have projects involved in making materials that we know, in a one step thermal process, will go straight from an iron exchange that will take things out of water into a very dense ceramic waste form, which can then be put straight into storage. So rather than increasing the volume by putting it in cement, you decrease the volume by thermally collapsing it into more dense material.

Graihagh - Because I suppose, ultimately, you still have a waste produce that you still need to bury?  How far away are perhaps from creating something that we could just dump in landfill rather than having to find these storage facilities?

Joe - I think you’re always going to need special storage facilities for those materials that have been used to take up caesium and strontium. The radionuclides themselves have about a 30 year half life, so the half life is the time it takes for the radioactivity to decrease by half. You want something that you’re going to be able to store safely until it really decays down to a low level, so you may be looking at being about to store it for 500 or 1,000 years. You won’t want to do that in your normal landfill so there has to be some sort of safe storage for that sort of timescale and that gets into the area of what’s usually called a geological disposal facility (GDF). That’s something that the UK is still debating I think.

Graihagh - Lynne and Joe have these materials - this xeolite and this hydroxyapatite, and they worked well in theory. But that’s not good enough, you need to be able to demonstrate it works in a real emergency. They had been working with Japanese institutions as part of their funding with the BBSRC, and that was for 10 years or so. But then Fukushima happened and it gave Lynne and Joe an opportunity to put their money where their mouth was. Here’s Lynne again…

Lynne - Well we all saw what happened on the TV and we were all horrified by it.  So there was a tsunami, there was an immediate problem with contamination, and the problem with contamination is continuing. The Japanese engineers, as I understand it, have built a wall of ice around the plant to stop water going back and forwards but there is an enduring problem of residual contamination including around the plant and also in the harbour water.

Graihagh - And what were the elements of concern?

Lynne - Mainly caesium and strontium, which have half lives of about 29 years. So left to their own devices, they would decay away to low levels but, obviously, it would take a long time to decay to safe levels and they need to be treated if they possibly can.

Graihagh - And that’s where Lynne and her team came in…

Lynne - Well, my colleague, Stephanie Handley, went out to Japan to try to develop the technology out there in the laboratories. For practical reasons it was quite difficult to actually get access to the site, to the actual seawater, so we did some tests with some Japanese seawater away from the actual site but in that general region. We put our own source of strontium in there that wasn’t radioactive so it was perfectly safe to handle and I did the tests with that. It was a surrogate system basically.

Graihagh - They needed to be able to show that their hydroxyapatite worked in this particular water, not the sterile water they’d been using in the lab, but salty Japanese seawater. Now, interestingly, hydroxyapatite is found on the commercial market already. What’s different about Lynne’s is that it’s made by microbes, a biological process. All the other stuff is made in a very different way via chemical reactions. Surprisingly though, Lynne’s worked and the commercially available stuff didn’t. Nature just does it better. Lynne doesn’t know why and this is something she’s still investigating...

Lynne - The biological preparation has got some feature about it that makes it better able to perform in seawater.

Graihagh - Did that then enable you to help with the clear-up at Fukushima?

Lynne - Work is still ongoing, obviously. Having done these preliminary tests, we’re now making a report back to the sponsors. We also did some work on some groundwater contaminating underneath a European nuclear facility, which is quite heavily contaminated with strontium, and the biological material removed that. That was real radioactive strontium 90 from a real groundwater that was contaminated and that was cleaned up as well, and the residual radioactivity was down to background levels. So we’re very pleased with the outcome of this particular project because it’s shown there’s certainly feasibility there for future cleanup.

Graihagh - It sounds very promising.

Lynne - It’s very promising indeed, and we’re well pleased with it. We’re continuing to work with the Japanese team, obviously, to see if we can take it forward now because the next step is to make more quantities of the material and actually get it out there for real life testing in the field.

Graihagh - Wow, okay. And when do you think that might happen?

Lynne - Certainly over the next few years. Obviously, a problem like this is not going to go away, but it needs to be cleaned up as quickly as possible.

Graihagh - So now that we have these tools, your hydroxyapatite and Joe’s zeolite as well, do you think that’s enough to assure people to move forward as we head in a possibly nuclear directions?

Lynne - I hope so, I hope so. Because obviously now, end of life of a reactor and cleaning up and decommissioning are very much in the forefront of people’s thinking. You can’t just walk away at the end, you have to factor in the costs of decommissioning and so every technology that’s available enables people to make predictions as to the likely scale of the cleanup problem and the cost at the end of the reactor’s life.

Graihagh - And Joe agrees these materials could help nuclear power become less of a daunting prospect because you can clean up accidents, but also get rid of all this legacy waste…

Joe - Yeah, I think so. I think if you can give an honest and realistic assessment that should there be another accident like Fukushima you are better prepared. That helps to reassure people. In terms of nuclear power that is, of course, one of the real worries that radionuclides get into the environment, might get into the food chain, cause cancers down the road, that sort of thing. It’s realistic for people to think about that, but the more we can do in advance to mitigate those effects, I think that’s an important aspect of new nuclear build and reassuring the population and reassuring ourselves that we are doing things that will help prevent problems should there be another accident.

Graihagh - Ultimately, we wouldn’t want an accident in the first place, but here your technology has some other implications in terms of decommissioning and closing down power plants?

Joe - Yes. Whenever a power plant is closed down you have storage ponds, you have contaminated plant, etc., that you have to decommission. And again, one of the aspects of that will be to potentially wash the material and wash the radionuclides off, or to clean up all the water, etc., and, again, you can deploy our materials for that. The other aspect as well should it be something like a terrorist dirty bomb, our materials are there ready to be deployed should there be something like that, I think, is another important aspect. In fact, the first co-funded project that Lynne and I had was aimed very much at that. Could we make a very portable system that could be deployed should there be a dirty bomb and you have a relatively small area contaminated, which you want to quickly decommission and then get rid of the radionuclides? What you’d like is to be able to say we’ve got materials that you can deploy here on a mobile plant.

Graihagh - I would like to hope it would never come to having to clean up after a dirty bomb, but a portable decontaminating machine - my brain is imagining a fire truck except instead of blasting water, it would blast out zeolite and hydroxyapatite…

Joe - I think that we’re aiming to make a real impact. As a scientist, it’s wonderful to do basic research and to take knowledge forward and to make new materials, but it’s also really rewarding to think I’m actually doing something that’s going to help in a very important problem. I think cleaning up nuclear waste, and legacy waste, and being prepared for accident prevention is putting something back into society for my training. And every scientist, to  greater or lesser extent, feels they want to do something that can help society.

Lynne - But, at the same time, obviously I’m very sorry that the testing of this technology has come about as a result of unhappy situations that have, obviously, affected a lot of people adversely. But, if it hadn’t been for the opportunity to test it then it would have sat on the shelf untested and then if it were needed one day in another circumstance, we wouldn’t be so confident because we wouldn’t have had the chance to develop it to the stage where it is.

Graihagh - A bit of a double-edged sword then. It’s amazing to think that a microbe could solve one of the fundamental concerns with nuclear power - the risk of an accident. Because, as we move forward, we need low carbon energy sources that we can rely on come wind or shine and that means as we build more nuclear facilities, the risk of an accident goes up. Admittedly, there’s still work to be done to prove that Lynne and Joe’s materials work outside the lab, and we probably need a larger arsenal of tools so that they work in all conditions, whether that’s water that’s acidic or alkaline, or even salty. But, is it enough to put us at ease when building new nuclear power plants? I guess that’s for you to decide.


Thank you for this great talk! I was a bit confused about the role of either the bacteria or the bio-HA itself in removing heavy metals. If I understood correctly the heavy metal salt is either precipitated by the bacteria into a phosphate or reacts directly with the already formed calcium phosphate (which is preferable as then we don't need the live bacteria)? There are no details on the way bio-HA actually captures metals, so I assumed it was through ion exchange; but then Joe explains the zeolite process by introducing it as "The other way chemically you can treat things is what’s known as ion exchange". So the bioremediation with the HA method is not using ion exchange?
Another question is about the name of the bacteria used to make bio-HA: I can't find references of bacteria named either citrobac or cayratia (but I found citrobac-ter and serratia)?

Pity that in your nuclear cleanup episode there was no mention of the measures being carried out to design and implement reactors that would limit the probability of chernobyl/fukushima style meltdowns. While I understand that the focus of the story was to talk about ways that cleanup could be helped by bio-HA and similar, there was still a feeling that *all* nuclear fission power is inherently dangerous, while planned gen IV reactors are much safer both in terms of reactor byproducts and the possibility of catastrophic meltdowns.

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