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in this special episode I begin by interviewing Tracy Taylor, an expert in vitrification who works for the UK's National nuclear laboratory I started off by asking her about the process of vitrification the process of vitrification is to convert material into a glass through rapid cooling so that's not able to crystallize and this involves heating up a mixture of glassy materials often to really high temperatures to a thousand degrees plus so that's nicely mixed and then rapidly
cooled either by air or putting into water so that these crystals cannot perform excellent and this is a process that is used to treat really radioactive liquid waste that's left over as a result of extracting useful fishing products from used nuclear fuel why is it important to vitrify this type of waste the reprocessing waste that comes through is in a liquid form and it has a high volume if we decided to store that as a liquid form it would need highly engineered containers and a large
footprint in terms of area to store that in so the best thing to do is to vitrify it this not only makes it a safe stable solid but also it reduces the storage volume to make it smaller it also has the advantage of being really safe it's durable there's glasses that we know that have been around since the Egyptian time so they're over 3 500 years old and they still look exactly the same as they were when they were made so we know it's safe and durable wow and I think we've
been vitrifying nuclear waste in the UK since the 1990s yes that's correct that happens on Centerfield site the plant was commissioned in 1989 and the first
classes that were made in 1990. so I feel like we've probably learned quite a lot in that time um yes yes so what are the most important things that we've learned in the intervening decades I think so so the early stages really fast paced in terms of trying to improve the process the NFL set up a research Department to look into how can we improve the process operations can we make it faster can we put more waste in because it was all really fast-paced a lot of research was
done a lot of money was put in to basically improve that process this is surprising whenever we all work together as a team we can we can drive things forward very quickly now sellerfield's sort of changing into a decommissioning phase there's different challenges different wastes that are needed to be treated so it's a little bit slower a little bit more targeted research it's the right thing to do take your time make sure we deliver the correct solution to the problem of course and I
don't think you've been working 1990s no how did you come to work in the field it was by chance really so about a year into my graduate program within the national nuclear laboratory I was offered as a comments on the vitrification test rig so that is a very unique facility within the UK it is a full mock-up of the um radioactive plants on settler field but it is completely non-radioactive so you can get Hands-On yeah it's really interesting opportunity it was only
supposed to be a two-year position and let's say the rest is history 12 years later I am still working in vitrification albeit on a smaller scale within the laboratory so you must really enjoy it in that case in the vitrification test rig is where the samples that were used in the art exhibition of comprom yes that's correct yeah it demonstrates that it's still delivering valuable research and interesting stuff to look at so what's your interest in glass or in
vitrification I have three interests in glass I have an academic interest so sort of the fundamental Science and Technology of glass and vitrification in fact I'm I'm the industrial supervisor to a PhD student who has generated some of the images that are projected on the walls here I have an industrial interest from the point of delivering a solution to the high-level nuclear waste at seller field and finally which is quite unusual where they would say for a
scientist an artistic interest I have keen past time of glass fusing I make balls I make ornaments I've even dabbled with glassblowing which is which is really good and actually in my free time can actually be seen walking down the beaches of West Cumbria with my head down searching for sea glass quite an addictive hobby so yeah my interest in class is wide ranging and I guess that sea glass proves it is quite durable as well it doesn't tend to dissolve in water it doesn't dissolve in water the
reason why it is sometimes so small it's just the pure bashing and the physical interaction with the stones on the beach that actually degrade the glass not necessarily the the durability and I like the fact that you don't just do the science behind it you're an artist as well with glass it's great so you mentioned that the point of retrification is to turn something into glass and it should be durable and all that jazz but how do you know when you've made a good glass what is good
what is good this is an interesting one so I would say for most of you you would see glass as being transparent so often clear brown blue green you can see through it so the glasses that are made on the vitrification test rig they are black and opaque so what makes a good product so I think the first and foremost it needs to be completely homogeneous I don't want any streaks in it I don't want any different areas that are different Flex different materials that haven't reacted with the glass
product and it can't contain a large amount of bubbles or cracks to me that isn't a very good product so that's the visual inspection so when we get to the product we have a look at it and these are those are the first two things we judge is then when we get into a laboratory setting we test things against International standards like the durability and then also when we look at the material on this or microscopic level to understand sort of the non-glass components okay so when you
said durability and you said they're a standard test is that about how it interacts with water it is yes so the durability in terms of a glass product is how it interacts with the water in a groundwater situation in a deep Gene logical repository if we have a product that is not very durable and what we term dissolves like a boiled sweet we know that that is not a not a suitable product so what we want it to be is long lasting for well it's not just tens of years hundreds of years it's tens of
thousands of years we want this to be a product that is stable and durable for that length of time so looking really far into the future and trying to predict what might happen yes you said that ideally you once that looks like glass and you're trying to avoid having crystals in there but the samples in the eye exhibition the images that we've got you can see that they do contain crystals so can you say a little bit about why they form it's mainly due to the cooling so as I mentioned before
that the process of vitrification is to form a glass by rapid cooling however on the vitrification plants at seller Fields the glass product is made into a steel containers and they're quite large and in the middle this is where the crystallization happens because the cooling happens a lot slower and these non-glassy materials the crystals can preferentially form okay and you said that ideally you don't want to have crystals in there you want it you want a good glass to be all the same so is
there an advantage to having crystals in the glass on occasions there can be advantages of having crystals in the glass they actually can be more durable than the um waste form of the glass other cases are not necessarily a disadvantage but they do need to be managed from the point of view of the operational plant and they can cause blockages or enrichment which is unwanted because it can cause downtime within the upper operational plant okay and a lot of the images in the
exhibition involve samples that have got these platonoid bearing crystals in them so why are they of interest in the vitrification of this nuclear waste platinoids are not soluble in glass at all the glass to treat high level waste that is they are encapsulated these crystals are surrounded by the glass Matrix and not part of the glass itself they are often denser and even in large enough quantities they can form a mixture for example like an alloy a mixture of metals and can settle out and
cause the operational plant to um shut down short and sweet I get it so I'm going to change tuck slightly and go back to talking about you it's kind of thing that surprises you about your work I think for me it's what surprises me about the work is the unknown I've been working within the area of vitrification and glass for 12 years and I still know very little about glass and it's surprising to say that it's a little bit embarrassing so for example I can do all
the background research and design a nice fancy set of experiments to do to prove a theory and the results will come back proving the opposing so you can imagine this can be very frustrating and intriguing so sometimes it's the unknown and how even though I have 12 plus years of experience I still know very little and that is just in the area of nuclear waste glass there's other areas like Dental glass which was really interesting there's metallic glasses the
field of glass is wide it's massive and I am a little dot within a sheet of paper I think that is most scientists you get really specific in like a really specialist area and there are always things you don't know that's why you do science right to learn more because you're curious about the world but sometimes you can be very convinced that I've designed this I know it's going to go this way or I know the results before or I'm predicting the results before and
when something comes back oh right hmm that didn't go as planned or I wasn't expecting that so yeah so from it can be very frustrating where did I go wrong is it my fault did I design it wrong and actually no it is quite a new field so yeah it's the unknown that surprises me along a similar line is there anything that intrigues you about this specific material or anything that has diamonds you about generally the nature of your work I mean you're working in a really
specialist field I'm intrigued about sort of the artistic side of glass so sort of like the uranium glasses that are made what we call the petroleum jelly type glass and how it's how it can full arrest under UV light and I think that's that's quite beautiful so that what intrigues me what astounds me is the work that I do to support seller Fields all the research that I've done supports the glass that's going to be stored in a deep geological repository for tens of thousands a year so my great
great great great great great great great great grandchildren and Beyond are going to be around when I have put that research into that class so it's just the time scales that's what astounds me about um nuclear waste the Legacy that all of these scientists and Engineers are leaving for the future the idea is that you should be sort you sort of um finding a way to manage this waste get rid of it effectively or dispose of it so that future Generations don't have to
be too concerned with it correct yes in terms of a legacy I'm not certainly not going to get a blue plaque on the side of a building it's just a nice thing to know that I was involved in that unless I you know have become a Nobel Prize winner and it might be a blue plaque on my house one day but it's just nice to know that the work that I do it has a purpose for the greater good of managing nuclear waste so that's all about how glass is made by people and how it's
used to immobilize nuclear waste glass is also made in nature by geological processes Brian O'Driscoll is a professor at the University of Ottawa in Canada having recently moved from the UK University where he was involved in this project what is your interest in natural or volcanic glass well volcanic activity is the surface expression of the formation and movement of magma within the Earth's crust volcanic glass is a special type of mostly erupted magma and my interests
in volcanic glass stem from trying to understand how the particular volcanoes that erupted them behave as well as understanding the material sort of physical and the chemical properties of the lava as it moves right after eruption up to the point that it solidifies I've mainly worked on obsidian flows from the aeolian islands in southern Italy where there are some spectacular examples preserved on the islands of Liberty and volcano wow that sounds uh quite complicated so I'm just
the volcanic glass form volcanic glass is magma that cools down very quickly from temperatures greater than 750 degrees Celsius so quickly that crystals have not been able to form it may also form from magma that loses its gas really quickly so perhaps as a result of a really dramatic volcanic explosion obsidian flows move extremely slowly this is because the magma that forms them is really really viscous so really sticky so their movement actually the movement of these obsidian lava flows
might appear to have more in common with a glacier than the runny basal flows that we see from places like Hawaii wow and the exhibition that this episode is part of is all about human-made glasses that have got crystals in and you said that crystals don't normally form in the volcanic glass but is it possible and what's the process that where that happens so crystals can form in glass but they're not common the cooling down process that causes glass to form means
that crystals have a problem nucleating so they have a problem getting started we can get little crystalline spheres made of radiating branches of crystals geologists we call these spherolites and you might see them in some of the samples associated with the exhibition these signify rapid cooling sometimes the magma that goes on to form volcanic glass can pick up bits and pieces of Crystal material from within the volcano on its way to the surface but these Crystal cargos as we we call them are
different to those that grow in the magma itself okay and as if crystals have particular interest to you uh yeah all crystals are are interesting to the geologists they they carry information about what has happened to them on their Journey from the initial nucleation and growth all the way to the final stages of solidification of that magma crystals can tell us about time scales of eruption about the chemistry of the magma and about processes going on within magma Chambers and within the
vents or the conduits that bring magma to the surface and for the nuclear glass samples the same is true the crystals are an expression of the bulk chemistry and the cooling regime of the glass so a really nice example of that is the shape of the power light crystals in the glass in this exhibition again as geologists we would call these or refer to their shapes as as dendritic or skeletal Crystal forms and that's a result of the really rapid cooling following or
associated with with quenching we would expect crystals that grow more slowly to have nice faceted sides I'm imagining diamonds now exactly exactly yeah yeah right so the crystals can tell you something about the history of that glass and they can tell you about what's happening inside a volcano absolutely wow one common way we use them is to look at different compositional chemical zones within crystals a bit like tree rings so we can map out within crystals
different zones that correspond either to changes in the chemical environment or changes perhaps related to eruption even wow and some of the samples on display at Florence Art Center they've got these platinoid bearing crystals in them do they have any particular interest for to geologists yeah so for my own interests I'm I'm a geologist very interested in the chemistry of platinoids in in natural magmas and how economic concentrations of these Metals form in natural environments so when I
discovered these nuclear glass similar materials contained platinoid compounds I was I was fascinated the Platinum Group elements so mainly routinium and Palladium isotopes that are formed in the the nuclear fuel in the reactor go on to produce these mostly unreactive metallic particles so they get petrified with the rest of the waste the interest from from the industry side in these materials concerns operational issues with the waste glasses so one example is
they can settle out of the glass if they're present in enlarge quantities and accumulate in large quantities and cause blockages perhaps that interfere with with pouring of that melt obviously this is a problem when the Melt being handled is is highly radioactive so I mean for me um I guess looking at the comparisons between how the platinoids behave in these nuclear glasses and natural magmatic examples is is really interesting because there's similarities and differences between both systems
right so you can use the nuclear waste glasses the non-radioactive surrogates of them to tell you something about what happens inside volcanoes absolutely absolutely so we can learn from human-made samples so human-made materials have the advantage that we can control both the chemical ingredients that go into making the glass as well as the conditions of solidification in carefully regulated experiments for example how quickly we let the glass cool or what volume of glass we choose
to make these can have a big impact on the end product and what that looks like and for sure we have therefore a better understanding of how nuclear glass is is made compared to the glass that forms from a magma that's cooked up at the bottom of a volcano where we can only make gases pretty educated guesses but gases as to what's happening platinoid bearing phases are they particularly prevalent in the volcanic glasses or are they like a really special case that need different consideration yeah
they're they're very rare so the concentrations of the Platinum Group Metals in normal rocks is on the order of parts per trillion to parts per billion and where we find economic concentrations of the Platinum Group Metals in in rocks also very rare very uncommon one fact that I like to tell people in respect of this is that most of the world's Platinum comes I'm talking about probably about 60 70 percent of the world's exploited Platinum comes from one ancient huge
magnet chamber in in the geological record that's located in in South Africa two billion year old magma chamber that today the solidified remnants of give us 60 or so of our Platinum that we use for anthropogenic purposes and I feel like Platinum is particularly useful but I couldn't really say what I guess because it's so rare ah that is interesting and it gets made in nuclear reactors so if we could extract it somehow it could be useful absolutely yeah absolutely so Platinum is
um it has a wide range of uses as do the other Platinum Group Metals probably the most common everyday use is is as an important part of the catalytic converters in in people's cars so helping reduce um greenhouse gas emissions uh indeed Yeah so basically the way catalytic converters work is they turn the toxic gases from your car from the exhaust fumes in your car to relatively harmless water vapor and and other things and all that from volcanoes and nuclear waste yeah so final question
this is quite a big question so I'll be interested to hear what you say and it's fine to say I don't know but how do you think this science could contribute to a wider understanding of the world or even the Universe um so Platinum Group elements form in a wide variety of minerals in the rocks that crystallize us from from Magnus on the scientific side they're useful because we can use them to tell us about the ages of deep-seated magmatic events within the Earth so personally speaking
from my own research I've used Platinum Group minerals to gain insights into the opening and closing of oceans or ocean basins on the Earth 500 million years ago other people look at Platinum Group minerals in meteorites and meteorite samples some types of meteorite contain Platinum Group minerals that are actually older than the solar system so these are a really cool mineral group the Platinum Group minerals they're a really cool mineral group to study understanding where Platinum Group
minerals occurs in rocks is also important because we can gain insights into the the natural environments where they're concentrated as precious metals they're critical metals and what that means is that they're going to be important for clean energy applications Platinum is going to be important for hydrogen fuel cells for example so go going forward to the energy transition and decarbonization of they could have a really important role to play wow is that in a similar way to the converter
the Platinum would allow a reaction to happen it's pretty similar it's similar in the sense that the Platinum Group Metals particularly platinum and Palladium for example their reaction catalysts so they speed up chemical reactions and that's why they're so useful [Music] foreign [Music]