Energy in crisis: nuclear goes up the agenda

The harmful effects of air pollution have been reported many times, and the stats speak for themselves: according to the World Health Organisation, breathing bad air kills 7 million people per year. But apart from its impact on physical health, something that's not been looked at in detail is how pollution may also affect mental health, especially in younger people who may be more vulnerable to its effects. This is a shortcoming that Erika Manczak from the University of Denver set out to explore. She explained to Chris Smith how she found a strong link between teenage exposure to ozone, which is one constituent of air pollution, and the development of depression…

Erika - The California environmental protection agency regularly collects information from air quality monitors on things like ozone. I was able to take that data and essentially map it onto a study we were conducting that was looking at adolescence in San Francisco over a four year period.

Chris - And the two overlap. You can then say 'Here's what the air is doing and here's what their mental health is doing.'

Erika - Exactly. Yes. We were able to take our participants' home addresses and identify which census tract they lived in and then take the state of California data and identify what are the average, ambient ozone levels for that census tract.

Chris - What relationship emerged when you did this?

Erika - We began following our adolescents right before the onset of puberty. When most of our participants were somewhere between 9 and 13 years old, we then followed those same teenagers over the next approximately 4 years, while each of them transitioned through puberty. One of the things that we found was that there actually was not an association between mental health symptoms and ozone at baseline when the adolescents were pre-pubertal. However, once they transitioned into puberty, we began seeing significant differences in mental health according to ozone level. Adolescents who are living in a census tract that had relatively higher levels of community ozone showed significant increases in depression over that 4 year period. Whereas adolescents who are living in communities that had relatively lower ozone exposure, actually didn't show any significant changes in their depressive symptoms.

Chris - Can you disentangle the effect of the environment? Because if I live in a really downhill place where my exposure to environmental pollution is likely to be high, equally my exposure to a raft of other factors; Crime, poor environment, poor outdoor space availability, and so on. Those could well be playing a role. Can you get apart those two different aspects to this?

Erika - Excellent question and something we were really concerned about trying to untangle, since this is essentially a correlational study. We can't firmly clarify whether our associations are causal, we can only look at whether these things go together. Within this study, we were able to also look at things like the number of families living below the poverty line, socioeconomic status of individual households, as well as things like how many people in a community had finished a high school education. We're able to show that our effects were not accounted for, by some of these other community level concerns.

Chris - This would argue then that there is genuinely something about exposure to this pollution, and whether it's the ozone or something else that's there, that you are not measuring, but it's there at the same time as ozone, either could be possible. But how do you think this might be happening then? What's the mechanism?

Erika - One of the things that we know from the research on physical health effects of ozone is that inhaling ozone can increase inflammation in our lungs, but also systemic inflammation throughout our body. In-turn, we know that systemic inflammation is associated with things such as asthma or cardiovascular disease. However, in psychology, we're also recognising that those same patterns of systemic inflammation are also linked to depression and depressive symptoms. Perhaps one of the biological pathways for our findings would be that inhaling ozone might increase inflammation in the body, which would then put adolescents at greater risk for depressive symptoms as they aged.

Chris - What's puberty got to do with it? You mentioned that there was not a difference at baseline. In other words, before they went into puberty, everyone sort of faring the same. Are you just more vulnerable when you go into puberty?

Erika - Yes. That seems to be the case at least for depressive symptoms. Thankfully levels of depressive symptoms in children prior to puberty are relatively low. However, once kids begin puberty, we do see a pretty significant increase in depressive symptoms, suggesting ultimately that there seems to be heightened risk during that pubertal change. Precise reasons for this heightened risk are a little bit unclear. It certainly might have something to do with hormones and also might have to do with really dramatically changing social environments. Within our study, our findings parallel this pattern pretty nicely, suggesting that prior to puberty we don't really see these risk associations, but once puberty occurs, we do begin to see some of these emerging.

Are you a lights off, or a lights on person? I’m talking, of course, about when you go to sleep. Some people like to keep a light on overnight, but now new research suggests it’s a bad idea and, instead, sleeping in the pitch black is better for your physical health. Naked Scientist Harry Lewis is a big fan of sleeping in total darkness...

Harry - I certainly do Chris. Ear buds out. Blackout curtains open. Ready for the day. That's right. New research coordinated by Phyllis Zee, chief of sleep medicine and department of neurology at Northwestern University, illuminates the health risk of sleeping with the light's on. I caught up with her, but when I did, she wasn't actually in Illinois.

Phyllis - I am in Rome right now. In Italy. In the eternal city.

Harry - It was the last place I went before the lockdown started to get put in place. It's quite a bright city. Although you are covered with the historic relics, there's a lot of light around.

Phyllis - There is a lot of light around in the center of Rome. I noticed that many of the ruins and beautiful historic sites are also lit at night. But the street lamps can be quite bright if they're right next to your window, especially when you're trying to sleep.

Harry - And that's what we're coming onto. A bit of research that you've probably recently, discussing the effects on our health if, when you are sleeping, you are in the presence of lighting. What are your findings from this research?

Phyllis - What we found was even in very healthy, relatively young people, having them sleep with their lights on compared to if they were able to sleep in much, much dimmer light, which was like less than three lux, that there was a difference. Those who slept in the room light had a higher heart rate throughout the entire sleep period, and the next morning, we challenged them with glucose. They drank a bunch of glucose and we found that the group that slept in the light condition had what we call 'insulin resistance'. That means that to keep their blood levels of sugar and glucose normal, the body had to secrete more insulin. That is what we see in, for example, people with type two diabetes. The tissue is less sensitive to the hormone insulin.

Harry - If we extrapolate this out, does that mean that if you were to sleep in the presence of light, not too much, but just a little bit, then this could result in somebody being more likely to be diagnosed with diabetes?

Phyllis - We know that having insulin resistance and increased heart rate during sleep, normally your heart rate should be going down during sleep, could be a risk factor for the development of what we call cardiovascular or metabolic disorders. There are other studies and one that was published just last year. What they found was that those who were sleeping with lights on during the night, whether it was from a lamp, a television, or outside light, were at higher risk for obesity.

Harry - I feel like because we've grown into this era of light being all around us. There must be a lot of research into the effects of light on our health when we are sleeping. Is that the case? Am I right in that assumption?

Phyllis - There's actually not as much research of light while we're sleeping. Most of our research has focused on light in the evening, usually before we go to bed. When you're awake, you're in bed and you're looking at your phone, you're looking at your light emitting devices. It's really more in that pre-sleep period. I actually was surprised. I don't sleep with the lights on, but there was a survey done in Britain that somewhere about like 30-40% people sleep with their lights on. I mean, that's a lot.

Harry - Yeah. I mean, I've got a little radio next to my bed and it actually pumps out probably enough light for me to just about see around. Maybe I should be turning that off before I go to bed.

Phyllis - Yeah. Especially the blue lights, your brain is gonna be much more activated by short wavelength or blue to green types of light than it would be for red or amber colours. I say sometimes people have to have their lights on for safety reasons, but think about changing that colour. Certainly if it's blue to something that's a little more on the red side. It can affect sleep. It can affect what you eat. It's really another modifiable factor that we can use to improve our health.

Driven by supply shortages - and pursuit of a green agenda across multiple geographies - many countries were already facing an energy crisis. Fuel prices at the pumps are at eye-watering levels we’ve never seen before, and some people have seen their power bills double in a matter of months. One consequence of the energy deficit is renewed interest in nuclear power, which under the circumstances is looking very attractive as an option, as energy consultant Jeremy Gordon, who runs the nuclear advocacy initiative “fluent in energy”, and Simon Taylor from Cambridge University's Judge Buisness School, explains to Evelyna Wang...

Simon - The UK was one of the pioneers in nuclear power and nuclear power has made quite a significant contribution to UK electricity generation over many decades. It's still around 15% of the power that we produce, but it's now shrinking, or about to shrink, quite rapidly because, on current plans, all but one of the older stations will close by the end of this decade. So, unless we build new nuclear stations, the nuclear share will shrink. The problem has been that new nuclear has proved economically very troublesome, both in the United States and in continental Europe.

Evelyna - Why is it so challenging to get a new station built?

Simon - Nuclear power plants are exceptionally complex structures. The underlying argument for nuclear is that you get a great deal of energy from a very small quantity of uranium. The problem is that process generates a great deal of radiation, which is dangerous, so you have to build protective structures around it. You also have to build in various backup systems to make sure that in the event of an accident or a loss of power, the plant can shut down safely. That essentially makes for a very complex structure which, in turn, Is very complicated to build. The good news is that there is learning by doing in nuclear, at least to some extent - there is a sense of benefit in building more of these stations because you get better and better at doing it, and the costs will progressively come down. How much lower remains to be seen. There is some evidence that things are getting better, but investors are obviously sceptical about this until it's actually happened, and that's where the government has to take some of the risk.

Evelyna - I see. If they were to build new plants, then where would these be located?

Simon - Well, the government did a sighting survey quite some time ago and identified several sites, which are almost all existing sites, where there are nuclear power stations of the first or second generation, some of which have now closed. These are all sites that have both the physical characteristics which, amongst other things, is that they need to be reasonably far from urban areas and they need to be on the coast because you need a lot of water for cooling and the grid connection is already there, which means you don't have to add a great deal of extra investment. They also have, for the most part, local support because nuclear power stations employ quite a lot of people; they generate very well paid jobs, additional economic activity in what are typically rural areas where there isn't a lot of alternative employment.

Evelyna - As a projection into the future, do you think we can count on nuclear technology as part of a clean energy future?

Simon - The main case for nuclear is that it is a proven source of reliable and predictable low or zero carbon electricity. The value of having predictable and reliable electricity supply, particularly in the winter, is quite high. So, I think there's a pretty good case for the UK to have at least some nuclear as part of the mix, as long as it's not outrageously expensive. As I say, the evidence is that it's getting better. With what's been going on recently in Ukraine, one message that's come through is that being dependent on imported energy is a risk. I would expect this to reinforce the case for nuclear in the UK and possibly other countries as well.

We’ve heard of nuclear fission - splitting the atom in common parlance - but there is another form of nuclear power, one that boasts the potential of being almost limitless and is said to be safer and cleaner. That’s nuclear fusion. Rather that breaking atoms apart, fusion involves pushing smaller atoms together to make bigger ones. It’s the process that powers the Sun, so we know it works. The challenge is trying to recreate the conditions inside a star, that make fusion possible, here on Earth! One of the places where they’re trying to do this, with some success now, is JET - the Joint European Torus, at Culham. Evelyna Wang went to take a look around...

Fernanda - Fusion happens when two light elements fuse and release more energy than what they had before.

Evelyna - That was Fernanda Rimney, a plasma physicist and JET's senior exploitation manager. JET stands for Joint European Torus. The shape of the reactor is included in the name. JET is a torus, or a donut. This shape is essential for the research.

Fernanda - The way we confine this very hot plasma, the very hot fuel that we need to produce fusion, is by using magnetic fields. The plasma is made of ironized particles. They stick to the magnetic field.

Evelyna - The fuel, or plasma, needs to be extremely hot, over a hundred million degrees Celsius, if the atoms are to gain enough energy to fuse. However, it isn't so simple. As the plasma heats up, it wants to expand outwards - it wants to collide with other matter which, in turn, cools it back down. The solution is to trap it with big magnets, forcing it to spiral around the reactor. The researchers here at JET have had success. At the end of last year, the team set a new record for longest fusion ever recorded: five seconds. I was keen to get a closer look at JET, but the first stop on my tour was the control room.

Fernanda - The glow that you can see on the screens, there, that's plasma. We have cameras looking inside the vessel. The simple view that you get here is just to check that everything is alright.

Evelyna - Am I allowed to ask what experiments they're running now?

Fernanda - Now they're running the clean up experiments; so, fairly low power, very low temperature experiments. From tomorrow, we go back to running some of the higher temperature experiments. We will put in some additional heating in the plasma, and then we go on with those until the end of the week.

Evelyna - We still need to work out the optimal conditions for experimenting with plasma. As funny as it sounds, that was JET's original purpose. It was built to study plasma. These experiments will better inform the nuclear fusion reactors of the future to allow us, one day, hopefully, to smash the current record.

Fernanda - Most of the experiments are a scan of something. You have your basic plasma and then you slightly change the heating power, the density of the plasma slightly, the magnetic fields. You try to change one parameter at a time.

Evelyna - Everyone looks so busy!

Evelyna - From the control room, it was a quick walk to the next building where the fusion reactor actually was.

Fernanda - It's going to be very noisy.

Evelyna - Okay. Wow.

Fernanda - Behind those yellow doors (is where that's coming from). Because the machine is operating, these doors are closed and there is another shield, a secondary shield.

Evelyna - The assembly room was a huge warehouse bustling with people moving around large boxes. There was even a giant crane plonked in the centre. Because JET is constantly in use, I wasn't able to get my hands on the actual reactor, but I did get to see the next best thing.

Fernanda - You can see the mock-up, up there.

Evelyna - That's the replica?

Fernanda - It's not just a replica. JET is built in sections like an orange - it's built out of eight octants. When they built it, they built nine. They built an extra one as a test. It was, full size, and it's that one.

Evelyna - From where I was standing, the replica looked like a metal donut propped up by big metal scaffolding. Compared to the real reactor, the mock-up was missing all of the external wiring, thick tubing for cooling water, and giant magnets. But still, I went up the stairs and pressed my face against the window.

Fernanda - This is the size of JET.

Evelyna - It's about the size of four shipping containers arranged in a cube. On the inside, it was a big hollow donut. Metal plates lined the walls like scales. Curiously, inside the mock-up, there was a large boxy looking robot. Fernanda told me that maintenance inside the reactor is carried out by the remote handled robot named Mascot. The replica of the reactor is used to train operators in manoeuvring that robot. To get a sense of what she meant, we went into the remote handling room.

Fernanda - This is the remote handling control room.

Evelyna - This is so cool!

Fernanda - Yeah, this is one of the coolest things ever.

Evelyna - Inside, there are two handles in the middle of the room, and on the walls were several big TV screens.

Fernanda - Basically, there would be one person controlling it from here.

Evelyna - So, they just stand right there and use the handles?

Fernanda - They use the handle, and the manipulator, and the mascot gets into the torus, and does whatever is needed from taking tiles of unscrewing things and then putting things on again. The mascot has got cameras, so there is a full view of what the person is doing. It is not an accident that the people who designed JET were all people with dual physics and engineering backgrounds. It was really at the core of the design and of the exploitation ever since.

Evelyna - The lessons and experiments done at JET inform the design of ITER or International Thermonuclear Experimental Reactor, a new fusion reactor being built in France that is twice as big.

New technologies also often require new materials to cope with the demands engineers are placing upon them. It’s a bit like the new generations of steels and casting methods that accompanied the invention of the steam engine. And in the case of nuclear fusion, the extreme operating conditions, and the high energy of the plasma at the heart of the process, means our present generation of materials can’t cut it, and we need to discover where they are vulnerable and how to make better ones, as Dr Andy London explains to Evelyna Wang…

Andy - There have been some really interesting results from JET. We're really interested there in the impact of the plasma on the wall, and that causes a number of different processes. It can cause erosion where you are removing the material, but the material which can be removed is also deposited. Sometimes that's in a very similar area; You have this erosion deposition process dynamically happening all the time. In other places there's parts of the reactor where you have lots of erosion and places where you have a lot of deposition. If we take a cross section through the material, you can see different layers and those almost correspond to different experiments in jets. Different pulses and different conditions that were run is almost like sectioning through a tree and looking at tree rings; You can see different levels of deposition that happened with certain run parameters. There we're really trying to understand what's the influence of how we're running the reactor on the materials surface's performance. We're looking there at the chemical structure, we're looking at the mechanical property change, because that tells us about how the components will perform, and ultimately feeding into the design of new materials that will be more resilient and help the reactor to run better and for longer.

Evelyna - What's an example of a new material if I'm allowed to ask?

Andy - Yeah, of course. One of the really interesting areas that we're looking at is materials that can withstand really high heat loads. You don't want your material to melt and you don't want it to sputter away. Tungsten is one of the main materials that we've used, but it has some disadvantages, it's quite a brittle material. We are looking at ways of basically making Tungsten more ductile. Instead of it bending and it cracking, which is bad from an engineering perspective, you don't want a component to bend and crack. Ideally you'd want it to bend and then just change shape, then you know that it's failed. You don't want it to crack open because that would be very bad. We can take basically the same principles of other areas of engineering. In composite materials, you can make fibre composites and when you make materials much smaller, you can make them tougher effectively, making Tungsten fibre composite materials. Even within Tungsten in these little fibres, that makes the whole material structure much stronger and much more ductile. Now we're looking at, when you then irradiate that with neutrons, when it has damage, when it has transmutation and it changes from one material into another, do you still get those same good properties and what happens when you expose that with a plasma. Does having these extra fibres in there mean you don't have a smooth surface. Does that mean you get more interaction with the plasma or less? And those are the kind of things that we're looking at.