Can Nature Clean up Nuclear Contamination?
Chernobyl was 31 years ago, but as nuclear power is one of the few reliable and low carbon energy supplies, how long before it happens again? We meet the scientists who are preparing for when the worst happens, looking for ways to use nature to clean up nuclear spills. Plus, news of a slug-inspired glue and the science behind the fastest bicycles.
In this episode
00:48 - New way to target tumours
New way to target tumours
with Justine Alford, Cancer Research UK
The main cause of death for cancer sufferers isn’t the original tumour - it’s caused when cells from the tumour break off and spread around the body. This process, known as metastasis, makes cancer much harder to treat. If you could pinpoint this process in the body, with a kind of biological red flag, you could gear treatment towards the tumours, without damaging the rest of the body. This sounds simple, but has proven almost impossible as different tumours behave in such different ways. But now - a team at the University of California Irvine may have found such a red flag, which- in mice at least - allowed for a targeted attack on multiple tumours. Georgia Mills spoke to Dr Justine Alford, senior science info officer at CRUK, who was not involved in the study, about the research...
Justine - Tumours are incredibly diverse, not just in one person, but across people with different cancer types. We know that they’ve got a huge amount of variety in the faulty genes that they have and also the molecules that they produce. So, in order to try and make medicine more personal, more targeted to try and reduce the side effects and not attack healthy cells, it’s really important to try and home in on features that are specific to the cancer itself. But that’s really tricky when cancers are so diverse and are producing so many different molecules and flags it can be become really tricky to try and home in on something and to try and find something that is found, not only in all the tumour cells in one person’s, but across different peoples’ cancer as well.
Georgia - What’s this new idea then to try and tackle this?
Justine - There are already some cells in the body which can naturally home in on a feature which is found around tumours. The surrounding around cells is called the matrix, and scientists have found that in some tumours the environment around the tumour becomes more rigid, it becomes stiffer, and that stiffness actually promotes the cancer and helps it spread and get worse around the body. There are some cells in our body which can naturally already detect this stiffness and then use that to then become a more specialised type of cell - these are called mesenchymal stem cells. These are kind of like a blank slate cell that don’t yet have their identity, and they can use this stiffness to work out where they are in the body and then how they should respond to these cues.
The scientists then use this knowledge to their advantage and they developed a new type of cell based on the mesenchymal stem cells, which not only specifically can pick up this stiffness, but also respond to it and then make a molecule which activates a chemotherapy drug. So they developed a really specific targeted system that only targets the tumour rather than giving the drug throughout the body which can cause more side effects.
Georgia - Right. So there’s this blank slate cell which recognise the environment that you find around tumours and then, when it finds this environment, it actually changes and can be engineered to change into something useful for fighting cancer?
Justine - Exactly. What they’ve done is really quite clever. They’ve tweaked these cells so that they make a molecule which chops up a pre-drug. The scientists will give a drug that needs to be modified to turn into a chemotherapy that then can kill the cancer cells, so it’s a two part system. The cells themselves produce this molecule and then the scientists can give the pre-drug, and then when that arrives at the tumour, this molecule that the cells are making will modify that molecule and then turn it into the chemotherapy drug which then directly attacks the tumor right at the site where it hurts.
Georgia - Have they tested this - does it work?
Justine - They’ve tested this so far in mice so it’s all early preclinical work but, so far, the results have been encouraging. They were looking at mice with breast cancer, and in these mice they found that these cells not only homed in specifically to the primary tumour, to the tumour in the breast, but they also homed in to the tumour that has spread to the lungs and it killed these tumour cells and caused them to shrink.
Georgia - So they’ve had promising results in these mice but how encouraging would you say this is, and how important is this in the grand scheme of things?
Justine - This process of spreading is called metastasis. Unfortunately, when that happens, it makes the tumour much more difficult to treat. At the moment we don’t have any treatments that can specifically target metastasis and that is a huge problem since cancer spread is responsible for the majority of cancer deaths. So we desperately do need to find new ways to target this and to stop it from happening. Whether or not this will actually translate into something useful in the clinic, we just don’t know.
It’s definitely promising and really encouraging, but at this stage it is very early and it is experimental so they will need to do lots more research. But the promising thing is that scientists have already used this kind of stem cell in clinical trials before, and they have shown to be safe in people. Obviously, that doesn’t necessarily mean that his particular type of cell that they’re using in this study will necessarily be safe and effective, but at least we do have some grounds for positivity there.
06:34 - Slug-inspired surgical glue
Slug-inspired surgical glue
with Dave Mooney, Harvard University
If you’re having an operation, or need a wound closing, you may be given a medical adhesive in order to help you mend. But according to research out this week, current adhesives have some major limitations, which could impact the success of a procedure. Cyanoacrylate - or Super Glue - for example doesn’t do well with wet surfaces, a problem when it comes to surgery. Doing its job as the body moves is also a challenge, and other adhesives’ sticking power isn’t all that strong. So what can be done to improve these properties? This week Harvard University have announced an adhesive that’s stronger and better able to cope with these wet and dynamic conditions. Katie Haylor spoke to Dave Mooney about the project’s rather slimy inspiration...
Dave - These slugs have developed a type of mucus that allows them to adhere very, very strongly to a variety of different types of surfaces, to do it in the presence of water and other fluids, and were very flexible and allowed a lot of dynamic movement. So the slugs had solved some of the key issues that we’re looking to address. While we’re not attempting to mimic how they do it in terms of there’s no mucus from slugs in our devices, we use them as inspiration for how one could try to design better adhesives.
Katie - Please tell me you had some slugs sitting around in your office which you were watching diligently?
Dave - Only fake ones unfortunately. We don’t do any actual research with slugs. A variety of scientists have been studying slugs for decades trying to understand their mucus and it’s properties and so we learned from all that science that had been done before.
Katie - Tell us about your product then - talk me through the chemistry?
Dave - There’s two key features to this concept for a new type of medical adhesive. The first is that you want to have a very strong chemical bonding to whatever you’re trying to adhere to. The other feature that we combine with this though is a material that can absorb and dissipate a lot of forces or stresses - an analogy might be here a shock absorber on your car. Here the adhesive both sticks really strongly and can absorb a lot of stresses so they don’t get felt at the interface and don’t cause the adhesive to peel off or fail.
Katie - Would this be someone stretching because they’ve recovering from a wound and they’re getting more mobile, or if someone moves around on the operating table? Is it those sorts of movements you’re trying to build in inherent flexibility in your adhesive to cope with?
Dave - Partly those types of movements and other movements that are naturally coming, for example, from different organs.
Katie - Back to the chemistry then, talk me through how you achieve this strong bonding?
Dave - We achieve the strong bonding by having long molecules that have a high density of positive charges. The key feature here is that tissues and cells in our body are overall negatively charged, so the positively charged molecules in our adhesive want to interact with the tissues and cells in our body. Then we provide the right chemistry so the the positively charged entities on our adhesive can chemically bond and form stable what are called covalent bonds with the underlying tissue and cells.
Katie - You mentioned this first layer, but what about the second layer - this ability of the material to absorb energy?
Dave - We have a what’s called a hydrogel, which is a long polymer molecules that are swollen in water. The positively charged molecules bind both to the underlying tissue, but also bind to this hydrogel. You can think of it as being somewhat squishy and has the capability of deforming very readily and, as it’s deformed, it can absorb and dissipate all these stresses or forces that the adhesive might get subjected to from the surrounding tissues.
Kate - Tell me, when you tested this in animals, which you have, what have your found?
Dave - We can use this to adhere medical devices to beating hearts, for example, pig hearts and have a very strong and stable adhesion that simply was not possible before. We can seal holes in tissues, for example, the heart or other tissues and have those prevent any type of bleeding or leakage of fluids. We can use these as a means of stopping bleeding on, for example, a lacerated liver. And it’s possible to use these on the skin, for example, as an adhesive and an agent to promote wound healing.
Katie - Why do you think this new product is important - in what ways is it important for surgery?
Dave - One is is enables new capabilities that we simply did not have before. For example, if we have a device we want to put on a beating heart, the current adhesives simply don’t allow you to stably adhere this type of device. Then we can also achieve some of the similar functions of the current adhesives but do much better.
11:54 - Mythconception: Asparagus makes everyone get smelly pee
Mythconception: Asparagus makes everyone get smelly pee
with Kat Arney
This week, Kat Arney’s holding her nose in search of the truth behind a whiffy myth...
Kat - Asparagus! It’s a perfect time to grab some of those homegrown tasty green spears. But for some people their enjoyment of the veg is somewhat tempered by an unpleasant side effect: stinky wee. It’s best described as a fetid, sulphurous smell, akin to bad breath or a particularly noxious fart, and can turn up within an hour or less of eating asparagus. But because only a proportion of the population can smell the stuff, it’s usually assumed that only those people make it. But the truth is a lot more complicated.
The first scientist to turn their mind - or rather their nose - towards the problem was Polish chemist and doctor Marceli Nencki. He identified the source of the smell as a sulphur-containing chemical called methyl mercaptan - also known as methanethiol. Given that some people make the stinky chemicals after eating asparagus and others don’t, it was thought that this was the key deciding factor.
In the 1950s, researchers studied families of stinky-wee producers and non-stinkers, concluding that the ability to make methyl mercaptan from asparagus is linked to one single gene - as yet unidentified - which presumably breaks down the asparagus chemicals into the smelly ones. A larger study in the 1980s also confirmed the finding - it seems to come down to one gene. You either inherit two stinky versions, one from mum and one from dad, two non-stinky versions, or one of each (in which case you’re still a stinker). But it’s not quite as simple as that. It turns out that not only do you have to make the noxious chemicals in your wee, you have to be able to smell them too.
Like the ability to metabolise methyl mercaptan from asparagus, the ability to actually detect the smell of the stuff is also genetic. But in this case there’s more than one gene involved. A large-scale genomic study by US researcher Lorelei Mucci and her team revealed more than 800 locations in the genome that are linked to the ability to smell methyl mercaptan. Their results were published in the Christmas 2016 edition of the British Medical Journal - never the most serious edition of the normally staid publication - with the title “Sniffing out significant “Pee values”: genome wide association study of asparagus anosmia”, and the suggestion that “Future replication studies are necessary before considering targeted therapies to help anosmic people discover what they are missing.” As a non-smeller myself, all I can say is I’ll pass.
So to be an asparagus wee-smeller you need to have the crucial combination of having the genetic variations in your metabolic enzymes that break down asparagusic acid to make methyl mercaptan, along with the right variations in your olfactory receptors to detect it. This does mean there’s a potential for a mismatch, which could make for some awkward domestic bathroom experiences if you’re an unwitting producer while your partner is a sensitive smeller.
15:06 - The science of faster bicycles
The science of faster bicycles
with Professor Stuart Burgess, University of Bristol
This week marks 5 years since the Olympic games kicked off in London -during which the incredible cycling team won a total of 8 gold medals. British riders are still going strong - as demonstrated by Chris Froome’s recent victory in the Tour de France for the third time in a row. But it’s not all down to the riders, there’s some serious science behind the bikes as Tom Crawford has been finding out. But first, a flashback to five years ago…
Announcer - Round the back and for one final time I think he’s going to do it. Chris Hoy claims the gold medal. What a moment in British Olympic history… a record sixth gold medal here, now at London 2012. Get on your feet for the knight of cycling. Sir Chris Hoy is in uncharted waters now…
Tom - It still gives me goosebumps even now. Not content with just reminiscing, I went along to this summer’s Royal Society exhibition to meet Professor Stuart Burgess. He’s an engineer who worked on the actual bikes used in the 2012 games and he had one to show me…
Stuart - It’s a track bike for going round the velodrome. The bike can go up to 50 miles per hour so it’s highly optimised for speed throughout the whole bike. At Bristol University, we’ve worked on the chain drive - that’s the chain, sprocket, and front chainwheel to reduce the losses in the drive to maximise the efficiency as much as possible to help the bike go as fast as possible.
Tom - So this is a case of British cycling recruiting academics like yourself to be like - guys can you please help us go faster using science?
Stuart - Yeah. Cycling is a really interesting sport because the bicycle has to suit the rider. It’s not like javelin, or shot putt where everyone has the same equipment and, therefore, there’s a lot of engineering science that goes into the bike. When a team like Team GB win a medal, it’s not just the riders - they are the most important part - but it’s also a reflection on the design of the bike as well.
Tom - What kind of things then would be incorporated into a bike design for, just in general, in terms of going faster and also in terms of a specific rader?
Stuart - Well, the aerodynamics are the most important for a bike. When a bike’s going 50 miles and hour, the aerodynamics of the rider are very important, so he leans right down. His clothing equipment is really important, they wear those skin tight suits but, also, the transmission is important. Even though the chain and the sprockets are a small part of the whole system it’s important to minimize the losses in those components and, so at Bristol University, we’ve done a lot of of testing. Testing of all kinds of lubricants, coatings, materials, sprockets to see which ones are the most smooth and the most efficient.
Tom - I’m a mathematician, and I notice you have a lovely looking equation on your display here. Could we possibly just go and have a quick look and you talk me a little bit through that?
Stuart - Basically we’ve got the drag equation for a bicycle. So, on the one side you have the power output of the rider, which is pretty phenomenal for these olympic riders, and on the right hand side you have the various contributions to drag. So you have the aerodynamic drag, you also have the rolling resistance of the tyres, you also have an acceleration term, but you also have an efficiency term for the efficiency of the transmission.
The reason for having that equation up there is to show the general public that engineers use maths and science to design a faster bike. Because, when you look at the equation, you can then see which are the important parameters. You see that maths is an important parameter, drag coefficient is an important parameter, the rolling resistance of the tyres is an important parameter. So an engineer looks at those and then says well I need to minimise certain parameters like the mass and the drag coefficient, and I need to maximise certain parameters like the transmission efficiency. So maths is very important to an engineer.
Tom - Just when you said the power output is phenomenal for an olympic rider, could you give me a comparison or just some idea of how powerful these athletes are?
Stuart - Well, when a commuter’s cycling to work that would typically be 60/70 watts. But when some of these sprinters are going round the track, sometimes it can be 1½ kilowatts of power. So it’s an incredible amount of power, and the torque they’re putting into the crank and chain is really very high.
Tom - I imagine you have to make sure these things are also designed to be able to withstand that level of power and torque?
Stuart - Yeah. That’s the great challenge because, on one hand, you need very lightweight components so you use carbon fibre and the bike itself weighs 6.8 kilogrammes so it’s a very lightweight bike. But, on the other hand, you have some of the most powerful, strong athletes in the world who are going to exert great forces on this bike so you have to make it strong at the same time, and that’s the great challenge of engineering.
Tom - Just finally, will this kind of technology make it’s way into consumer bikes?
Stuart - Yeah. That’s a question that we’ve been answering during the week. Yeah, after a couple of years this technology drips down to club cycling etc. But not only that, we’re hoping we can spin off some of the technology onto other chain drives in factories to make factories more efficient. So it’s not just about the olympics, we want this to have a benefit for society.
20:50 - Understanding animal emotions
Understanding animal emotions
with Piera Filippi, Planck Insitut
Understanding other people's emotions plays a fundamental part in our ability to communicate. But does this extend to animals? Can you tell when a crocodile, frog or chicken is in distress? A new study from the Planck Institut in the Netherlands suggests that we all have some ability to sound out stress in other species. Their findings indicate that humans mainly rely on specific tones that indicate agitation, called emotional arousal. Lead author, Piera Fillipi, explained to Izzie Clarke, how it worked…
Piera - The emotional arousal is the level of responsiveness to external stimulation. This might range from very subdued to highly excited. So, for instance, right now you hear my voice, it’s quite relaxed, there are no dangers around me you might infer from my voice. But if I start talking in a more agitated way you might infer that there’s something around me that is disturbing me. And this is something quite clear we can infer from the voice of humans as well as of other animals it turns out.
Izzie - How did you investigate this?
Piera - There were basically two main questions. The first question was simply whether humans are able to recognise levels of emotional intensity or arousal in animal calls or animal vocalisations. If so, we wanted to see whether that is a biologically rooted ability or instinct, so to speak, or whether it’s driven by the cultural background or the language that the given human speaks. Maybe there are some language speakers that are more sensitive to sound motivation than other language speakers.
We included three different groups, so we had native speakers of English, of German, and Mandarin which is tonal language. And it turned out across all of these languages humans perform equally good in recognising the emotional intensity in animal vocalisations. This suggests that this is an ability that is actually biologically universal so it isn’t only the given language that humans speak.
Izzie - To test this, Piera and the team played two calls from a range of animals. One of the sounds displayed a high level of emotional arousal, say when an animal was agitated, and another when it was calmer with a low level of emotional arousal. All the participants had to do was choose which of the two sounds was the agitated signal.
Piera - I found that humans are particularly good in recognising higher level emotional intensity in animal vocalisations. To do so they rely on certain acoustic features in their calls, particularly on the acoustic features that I related to the tone of voice, and this applies across all of the species we included in our study. So tonal voice, the way we modulate our voice, is crucial in expressing emotions and it is crucial in perceiving and recognising the emotional content across all of these species. These species span from little frogs, alligators, up to Barbary Macaques and humans.
Izzie - The reason why we’re able to recognise these signals is still being explored with further research looking into frequencies of these noises, and whether it might even work in reverse. Can animals actually recognise when humans are agitated? And looking to the future, these findings could help improve artificial intelligence...
Piera - This finding can be applied in progressing technology for emotional expression and recognition in something that sounds quite cold, so to speak, which is artificial speech like speech that is synthesized artificially. I think that it would be a good idea to integrate what we know from findings on actual animal vocalisations that are emotional and apply that to emotional expression in synthesized speech.
25:29 - Are we ready for the next Chernobyl?
Are we ready for the next Chernobyl?
with Iryna Mikheenko, Lynne Macaskie & Joe Hriljac, University of Birmingham
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 worldnuclear.org 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.