Inside a Nuclear Reactor

this episode was made possible by Wix and will tell you more about them later in the episode today we're going inside the nuclear reactor and not just any reactor but the reactor that is used to make the rare isotopes of elements like berkelium californium the ones that are so important for synthesizing the super-heavy elements so this is an old reactor and the reason why this reactor is here is because of a gentleman named Glenn Seaborg he had a lot of work at Berkeley labs and he had a vision of practicing that work on these heavy elements but he didn't have a great supply of it and we can look forward with that hope that nuclear energy will become the servant of all men everywhere he pushed the Atomic Energy Commission through the 50s pushed and pushed and pushed and finally of course he won the Nobel Prize in Chemistry 1951 and he did a little bit of credibility and and he finally made some progress in the late 50s 1958 and the Atomic Energy Commission said yeah we want to do this we want to build a reactor to produce heavy elements for you to do your chemistry and so the Commission looked around the country at the time and at that time in the late 50s there was a lot happening with nuclear reactors a lot of drawings a lot of designs being put on paper particularly here in Oakridge America's atomic city at Oak Ridge Tennessee has been open to the public and even the opening was by atomic energy watch that tape Oh Craigs had the only school that was specifically designed for reactor engineering it was called the Oakridge reactor engineering school and this gentleman who's on the wall dick chevre ttan has a plaque up here he was a student in that school at that time and he'd come up with a concept and the Commissioner of the Atomic Energy Commission saw this concept and said yeah I think this is the one Len T Seaborg needed a nuclear reactor with a high Neutron flux so that he could get the elements to study up till then he had gone to the sites where there had been nuclear tests and looked among the rubble for traces of these elements and obviously this is not very environmentally friendly and there's a limit to the number of nuclear tests that can be done and people are not very interested in doing a test just to make some exotic elements in 1960 they broke ground on this site and then they put the reactor building in and put the reactor in and they were up and running by 1965 so for the first 20 years of operation we produced these heavy isotopes small quantities but we produced it very regularly we operated very regularly and we operated often meaning the total number of days we operated over the year was very very large 75 percent now we operate much much less about 50 percent of the year we actually operate and our mission has shifted over the decades now our mission is neutron scattering condensed matter physics but we still have an isotope component we still make isotopes so we got a big window this is our Bay our reactor is actually to the right side of the pool the yellow bridge has a dam underneath and that well that doesn't have a dam today I can see the dam is out the dam has actually moved to the left we're currently shut down for an outage and but the reactor is in the pool on the right kind of you see the stairway going down that stairway goes down to a platform basically a grating so we can lower that when we have the dam in place we can lower that pool we can actually walk down there and perform maintenance and repairs in the pool is the reactor vessel we're a pressurized reactor so we have a very sizeable pressure vessel and then the reactor core is actually inside of that vessel the vessel itself is it's eight feet across so what two and a half meters but the core inside of the reactor is where all the action happens this reactor is designed to produce neutrons not to produce power it's not trying to make electricity like say Chernobyl reactor was so it's small and it produces the neutrons at a very high rate and then it burns out quite quickly each reactor core only lasts at its proper operating power about 25 days less than a month the reason we pressurize it is to increase the boiling point of water so that we can cool without boiling our reactor because we produce an enormous amount of heat along with an enormous amount of neutrons what's the liquid in the pool plain water just out of the tap water you purified a slightly demineralized there are still some minerals in it but we do demineralize it water is all for cooling all we're trying to do is remove heat we produce a huge number of neutrons in ways that we can explain a million billion neutrons 10 to the 15th neutrons every second hit a square centimeter that's just one square centimeter it's a huge number of neutrons so the pool water is separate from the water that's inside the pressure vessel and the pool water remains at about 100 degrees Fahrenheit the water inside the vessel starts out at about 120 degrees Fahrenheit as it passes down through our reactor core it raises about 36 degrees Fahrenheit exits at about 156 degrees Fahrenheit way way below boiling this is good for us power reactors they want to generate steam but we don't want steam steam would be bad for us we would like our water to be liquid it it's blue because there's so much metal in there it really isn't blue and we get that question often but it's pretty but it's not like there's an additive so this is a mock-up of our fuel our fuel is different power reactor you know uses fuel rods we use fuel plates but they're arranged in a very strange arrangement for compared to other research reactors even our fuel is met is placed in these plates that are in here these are curved plates and we basically have two fuel elements an outer element and an inner element this part in here which has rods these are not fuel rods these are target rods this area is an area of very high Neutron flux so this is the business end of our reactor for making isotopes when we make californium 252 which you may have learned about next door or Berkley m249 we make it in here in the flux trap the main point of the reactor is to have a tube in the middle in which you put your samples in fairly long thin essentially metal test tubes to be radiated and neutrons are important because these heavy elements can be formed by bombarding lighter elements with neutrons these fuel elements are mostly aluminum but inside of these fuel plates is uranium so we have you we use you 308 which is uranium oxide and it's sandwiched in between two aluminum plates so we we basically protect the uranium but allow it to cool very effectively by having these very small channels to force the water through and that's why we raise temperature from 120 to 156 it all all that heat transfer happens through these plates so the plates themselves are about 24 inches but the we call the fuel meet the uranium is really about 20 inches tall so about 20 inches of fuel meet and and the rest of the aluminum our fuel actually the uranium comes from the y-12 national security complex and we get our uranium for free however the free part is metal chunks and we can't use metal chunks in our fuel so we have to pay to have our uranium converted to you 308 oxide so y12 does that they convert it to an oxide and then our fuel is actually fabricated at BW XT technologies which is in Lynchburg Virginia they are the ones that take that you 308 and they blend it with aluminum powder and they form these compacts so basically the you 308 and the aluminum are blended together they press it into these compacts these compacts are then put into this aluminum picture frame so now you can envision there's uranium there's aluminum in this in these middle sections here and this is just all aluminum and then we sandwich that with an aluminum plate then we take that plate and we roll it out then what they do is they form it into this shape and this is a unique shape this shape is called an involute shape what makes that shape unique it's the only geometric shape that you can stack around a circle and maintain a constant water gap thickness you can't do that with a circle you can't do it with anything else it's it's and this involute shape so here on this dummy version I'm looking at these are representing to feel the uranium phase like this just like pretty fluted area here yep right yep both these fluted areas are where the uranium is that's where we generate all of our power are all our Heat all of our neutrons and how are you making sure that most of the neutrons go to the center where you want I assume you want them to go to the center more than the outside well you can't really control that however that's the that's the amazing part of this unique design that Dixie Burton came up with is this flux trap he called it a trap but it's really just a high concentration there's no such thing as trap and can't trap a Neutron but you can create a high density of neutrons and that's basically what this does however those neutrons do go outward to in fact if we look at this mock-up this gives us a more complete picture of the of the reactor core so we have our flux trap that we saw over there we have our fuel we have a small region called our control region and then we have a reflector region so these are all annular regions our reflector region this is necessary for the reactor to work and so is our control region the reflector is made of beryllium and beryllium is a unique material its unique neutronic Li because when a neutron hits beryllium on average about 2 and 1/2 new neutrons are made from that their lower energy than the ones that came in and hit it but so you get 2 and 1/2 neutrons some of those neutrons go back into the fuel and cause that fuel to fission more and you build up this population of neutrons some of them can be used for experiments that are out here in the core in the reflector so you just let your descent we've got this great neutral environment the scientists like what else can we chuck in there to see what happens yeah so in fact out here what we generally make these days is we make plutonium 238 for NASA so we start with neptunium 237 and we irradiate those neptunium target for three of our operating cycles which is about 25 days easy so 75 days of a radiation and we convert about 10% of that neptunium to 37 to plutonium-238 then we take it to the hot cells next door that you just visited they extract that they ship it out to Los Alamos and eventually it ends up in Radio thermoelectric generators RTGS for example like the one that's on Mars rover Curiosity or the one that's going to be on Mars 2020 Rover between the coal and the reflector there are plates containing the element europium one of the rare earths europium in this context is a very efficient absorber of neutrons so it stops the neutrons from the core getting to the reflector and the control plates are in two parts so that you can move one up and one down and adjust the size of the gap between them so when you're ready to go everything is assembled the reactor is in its case in water for the cooling and everything is shielded then remotely you can pull these control plates apart and the outer one moves up and the inner one moves down and we create a window of communication between the fuel and the reflector so the neutrons can communicate and we build up that population of neutrons and then we finally go critical then what we'll do is for the remainder however long it takes if it takes 23 days 25 days 27 days we pull these plates apart until they're all the way out and once they're completely out and we can't maintain 85 megawatts we shut it down but at any point if you if you shut the window through the whole thing would go out what it turns off what's going on in the center where those where the rugs are so those targets we do produce other isotopes we make nickel 63 we make selenium 75 we make californium 252 and then we also make some these other elements the like the berkeley m249 what are the rods typically made of or does that depend on what you're trying to achieve it depends on what you're trying to achieve but most of the targets most of the components in in the reactor and especially the targets are have a have a capsule housing made of aluminum so most targets are made of aluminum and then they have some material interest inside in the case of plutonium like I discussed in neptunium 237 in the case of californium 252 we start with heavy curium which might be curium 246 or curium 248 for selenium 75 we have selenium 74 targets so we generally want most most of the processes are to capture neutrons to get to the next isotope we are fairly full but we have a regular routine set of radiations that we do particularly for isotope production but we also do a lot of materials radiations testing in here we have a lot of materials for material science in that core it's one of these it lasts for 25 days when we take it out we put a brand new one in each one of these is about 1.8 million US dollars and it lasts for 25 days so and then what happens is it refurbed or that goes in the in the bin so what happens is so as I said we're in an outage this is a temporary just a little cap to cover so we don't drop things in there but this is our vessel head this is the part that's about eight feet in diameter this is the grating you can see that you can actually walk down the steps to get to not a lot to see here because we're not operating usually when we're operating you can see a blue glow you get the shrink off radiation glow so you slide the core in today idea yes so it's actually quite deep down in there so we use very long tools attached to things and the operators roll the bridge over and then they can lower the fuel down into the core location it's that always an exciting day for you guys like there's everyone come out and watch and go we're starting a new Under like just routine now I will say it's fairly routine now putting it in taking it out is more exciting but generally that happens overnight so not a lot of people come out overnight but when you take it out you take out elements that look like you get the nice Cherenkov glow we don't have a lot of them right now that are glowing but and actually we don't really see many glowing usually we would have these would be glowing that they've been out for quite a while we've had a long outage so they've had time to decay so these are out ones cooling down these are old ones cooling down [Music] they always stay underwater and they stay in this center section of the pool for maybe two or three years and then eventually they go over to these racks which are three tiers so we can hold a lot of elements over here and then eventually they get shipped to Savannah River Site where Savannah River Site will dissolve them and extract out the good remaining material and recycle that into a program that supposedly makes power reactor fuel not very familiar with their program how do you get to stuff out that you've just made like you know all that all those cool isotopes that everyone's dying to get their hands on how do you get them out of there of the core and all those surrounding little cylinders so that's that is a challenge and I will say that is what our operators do with long tools it's like a laparoscopic surgery to get these out so it would be nice and you look at the top of this and you see these plugs and holes those plugs and holes initially you think oh those line up with the holes that are on top of the reflector but they don't the reflector is actually only about this diameter everything we do has to go through this one hatch so they're working down there and they're going around things with these long tools it's arduous it's difficult but they've they're very talented at it so it is difficult to get things out but we do we do it routinely every cycle and then they literally take them and they just keep them underwater they drag them across to the other side of the pool and then we can we can store them we can put them in shipping casks and then we can ship them over to the hot cells or wherever they're going to go these few elements while they're not producing neutrons or many neutrons they are still producing a tremendous amount of gamma radiation so we use these we have developed a small canister that can go down into that flux trap area and we can fill that canister we can stream water or electricity or whatever we want into that canister we can do high-intensity gamma radiation these are our control plates you can see that I described the two cylinders okay that was a little bit of a stretch they are two cylinders but the inner cylinder is one contiguous cylinder the outer cylinder is actually made up of four plates and you can see one of these plates here on the windowsill that's an example of a control plate these are very difficult to fabricate they take a tremendous amount of time they're very expensive remember these have europium oxide inside as a meat and they take two years to fabricate a set like this so when we do shipments we can actually pack a truck in here and it comes right over to this area where these gray squares are and we can use the big crane and bring the big shipping cask and set it down the shipping cask four californium to 52 targets is quite large it's a nine foot diameter sphere that they've painted white and call the cue ball it weighs 25 tons so it's not it's not insignificant and it can get set onto a truck very exciting when they ship californium and plutonium targets are shipped in the same in the same cast I was really impressed that they're using this reactor for all sorts of different experiments not just making the new elements they also have beam lines coming out from the reactor generating beams of neutrons the reactor core is that way the beam you can see the red lines designate three beam lines there's actually a fourth one on the far right that doesn't get a red line so we have four beam lines that come down and they actually get split even further because we have more than four experiments out here so these large tanks are called Sands tanks small-angle neutron scattering tanks they get evacuated there's a detector plate a large 1 meter square detector plate inside and they can use the beams of neutrons for what so called neutron diffraction which will allow you to do all sorts of interesting experiments the one that really excited me was that you can take a diesel engine like for a car and you can image the fuel being squirted into the engine block by shining neutrons through the block of a running engine and because the fuel contains hydrogen atoms which absorb neutrons strongly you can see this jet of fuel going into names and when it's running without disturbing any of the workings of the engine have you seen our new periodic videos website yet we made it with Wix which is the sponsor of today's episode this is what it looks like and if you're creating a new website or maybe ditching an old one because it's become a nightmare to maintain then you really should have a look at Wix they're drag-and-drop interface makes designing a website so simple elegant it's actually kind of fun too you can stick pretty close to there huge range of templates to get things going or you can go really deep with customization tweaking every tiny little part of the site you can even customize things I didn't know existed on a website they've got everything go to wix.com slash go slash periodic videos use that slash periodic videos so they know you came from here whatever you're doing these days you really should have a website and Wix is the place to go to make it Wix comm slash go slash periodic videos Walmart is in the middle of South Australia Woma is actually an Aboriginal word for a throwing device and that's how they say appropriate yeah cuz launching rockets and things yeah the black stamp so here they're taking all their supplies Australian servicemen and scientists paid a big part in the operation which included the construction of a tower the tower that vanished instantly when the atomic weapon was exploded on it

Channel: Periodic Videos

Views: 1,730,215

Rating: 4.9272933 out of 5

Keywords: periodic, videos, chemistry, oak ridge, high flux, isotope, nuclear, reactor, neutrons

Id: P99C051arMo

Length: 24min 15sec (1455 seconds)

Published: Thu Jul 25 2019

Reddit Comments

[u/[deleted]]

Loved the opening at Oakridge - was that an actual, tiny nuclear detonation? Or just something that produced a cute little mushroom cloud?

[u/gusto_ua]

The Black Stump @ 24:02

[u/thru_dangers_untold]

Okay, this might be a new favorite of mine for Periodic Videos. Normally when you see Cherenkov radiation it's not moving around--but watching the glow follow the canister around made it seem more surreal. Very cool footage!

[u/NogsLaugh]

Excellent & Fascinating.

And besides the fact that that is so, it could have been 37 hours longer -- another case of the workers/people doing the things that the profiteering idlers haven't really a clue about, making brilliant use of every possible-purposing! So many interesting experiments and utilizations going on!

Great great stuff (and things).