Nuclear Safety Expert Robert Budnitz on Fukushima Disaster

my name is Teague Majumdar I'm the professor in the physics department as well as the current director of the Science Center at Williams and it's a pleasure to introduce Robert button it's and let me just say a few words about him in addition to being someone with impressive national and global insights and connections to this important topic about which he'll speak tonight he's a person who has some interesting local connections and I thought I would mention those as well we're grateful that he's here this month and that he's willing to to join us and talk to us this evening he's an expert on nuclear power on reactor safety on waste management and safety he graduated from Pittsfield high school married locally and his into the press key family a family who's who's who's very well-known and whose generosity is very well-known on this campus he was a graduate of Yale College and got his PhD in experimental physics from Harvard then went to Lawrence Berkeley Lab where he worked in the energy and environment division including a stint as head of that division did a stint in the Nuclear Regulatory Commission then on to Lawrence Livermore National Lab including work with the Department of Energy back to Lawrence Berkeley Lab where he is now and in particular it's important to note that when the Obama administration wanted to put together a kind of a local US task force to coordinate reactions to the Fukushima disaster that Energy Secretary Steven Chu put together a panel of five US scientists including Robert buttons so it's a particularly great pleasure to welcome him to Williams not to Williamstown but to Brooke Rogers Hall may be to this evening and we look forward to his remarks thank you and I got dressed up which I probably shouldn't have and I have two other local things to say how about those Red Sox were in first place that they all-star break right and secondly a half a century ago my wife and I were married in the Williams College faculty house just right over here and she's sitting right over there so it shows you 50 years you can do it too I'm gonna try to explain what happened in Japan I'm gonna try to explain the details as best I can for a lay audience about what led to the accident and then at the end I'm going to try to explain what it means for us it's awfully hard to predict the future of course I can't even predict something's gonna happen a month from now never mind long-term future but I'm going to try to give some insight into the sort of things that we already know and see if we can figure out if we can what it means a lot of you perhaps don't know how extensive nuclear power is around the world we have just over 100 nuclear power plants the United States 104 of them to be exact it generates about 20% of our electricity there are 400 around the world we have about a hundred of them Japan has about 50 of them and you and here's a map of where they are they're on about 15 sites all over Japan and the nuclear power plants there generate about a third of their electricity so it's a lot of electricity they decided very early on to have an important nuclear power program because they really needed it we don't in the sense that we've got a lot of coal and we've got other ways of making electricity but they don't have any natural resources to make electricity tall except hydroelectric so they know the rather than import oil and gas and coal they made a decision very early to have an extensive nuclear power program and they do said it generates about a third of their electricity and you should know that until this accident they had the reputation around the world of having one of the very best programs of reactor safety everything they did was great when everybody else around the world including me went there we observe that the wreck of small incidents were very few and not important they just did wonderful job with their design and maintenance it was just a terrific program people I'm elated them and all of a sudden this disaster has revealed to us everywhere everybody around the world that things weren't what we thought in Japan and we're still not sure whether that's going to be true of us too I'll come to that later that is it's obvious now that the Japanese made some fundamental errors at least at this station and at some of the others which I'm going to explain to you now it doesn't mean by the way that all these plants are unsafe these accidents are pretty unusual and very rare but it still shouldn't have happened and I'm going to try to explain why so there they are you can see on this map and that that bullseye is the earthquake off the cut off the northeast coast that happened on March 11th it's now just four months today along the northeast coast there are 14 nuclear power plants they're shown on this on this map there are three of them in a place called Onagawa and then down the coast there are the six at Fukushima one that's where they had the accident and next to them is Fukushima two with four more and those ten are pretty much identical in their design you should know that they have the accident of fukushima one but at Fukushima two they didn't have an accident they they wrote it out fine and they shut down and everything's fine there and it's only a few miles away it's about five or six kilometers from the other one and then another one down the coast all of them are pretty much identical and you can see that the six at at Fukushima one we're all commissioned in the 70s here's a here's a better explanation in a in an airplane view you can see the six units there they're these big box buildings there see if I can point them out well you can see the great big box buildings there and you have no idea how big they are until I show you a picture that really shows how big they are but the crucial thing for the purposes of this accident besides their being right next to the sea is notice what was going on the first three units were operating units one to it they were operating each of them had a very large disasterous core meltdown accident and very serious accident the next three weren't operating they were in an outage plants going to an outage every 18 months or so sometimes for about a month to add new fuel and then they start up again but in this case all three of them were in an extended outage going going on for six or nine months because they were 30 years or more into this they were repairing and replacing some major equipment so they could run for another 30 years and that was scheduled to be done on the other three later so this is crucial you need to remember it's units 1 2 & 3 that had the accident four or five and six per unit outage they were shut down there was nothing wrong everything was fine now here's the we're not looking at the print up there this is a picture I took from someplace else to show you and I did this work you know look at that that's great I can point with that to show you about the earthquake and the tsunami this was as I perhaps you know the largest earthquake that is strict in Japan in recorded history which goes back 2,000 years it was a magnitude 9 and the magnitude scale is a logarithmic scale it's 30 times more energy than the magnitude the magnitude a and this earthquake struck about 70 miles offshore and its length was 400 kilometers about 250 miles long is that's what this this length is shows you now it's important to understand how this earthquake work does let me go back because I'm gonna I'm gonna show you how this worked because it's important to understand how that tsunami comes about and why for example we don't have a threat like this in California this fall ruptured by dropping like this okay dropping like this one side drop compared to the other side as opposed in California where our faults go like this side to side and you can't get a big wave no matter what you do side to side compared to something like this in the middle of this 250 mile long rupture the the one side went down about 75 feet you gotta listen that over about 10 seconds went down 75 beef now it went down less as you went to the ends but it went Donald and if you do that try that in your bathtub you get a big way it's like a right it went down and it's just a huge huge rupture and it dropped like this it's a subduction zone earthquake and that produced in this picture gosh I can show you this little thing on I can do it from here and you can see it that produces a wave that goes in both directions you know goes down like this in the millender's this goes in both directions the this is this shows it just after it the one that's going east crosses the Pacific it finally came to California but by the time it got there wasn't any believe you know what it dissipated but the other ones going west and it impacted the shore from the southern end of the Hokkaido Island up north and this whole section here get impacted that shore with very very large tsunamis that were that were way beyond anything they had anticipated and it was over 250 miles you just end it with Asami that caused a couple just want to let you let that sink in now most people think that tsunami looks like that and it doesn't I put up this picture I got it off the web it's one of the most famous pieces of art in the history of art centuries old a famous old woodcut that was then you know colored and this is what a lot of people have in their mind when they think about a big wave but it's not that what this is is a wave of a completely different kind and I drew this just by hand and show you what you see there imagine this thing is moving from left to right and what you see there is what this wave looks like the wavelength is a couple miles long and out in the open up open ocean the height of it is about 10 meters or 30 feet roughly that's this one it varies a little bit but it's roughly like that and so if you had a ship out there it would go up a little after all a ship is higher than 30 think you could draw it on the thing it would go up a little bit and go down a little bit and the open ocean the ship wouldn't get any trouble it's just it would see it but it wouldn't be disturbed by it but this thing is moving at 200 miles per hour a little more actually and as it goes to the right and it's going towards the shore suddenly it hits the shore and depending on the topography whether it's shallow or whether it's steep and whether there's a harbor that channels it or whether it's spinning out you get different heights and tsunamis there but it's not a wave like that it is in fact a sea level rise that takes place over about a minute and that minute it goes from wherever it was let's say in the in the case of this particular reactor site up 46 feet but it's a sea level rise and then a minute or two later it goes back down and by the way it goes out and then there's a slosh again but it's that so it's not how do I know it says it's not a way it's a sea level rise and that sea level rise varied from one side to the next considerably and although at the reactor it was about 45 or 46 feet oops now here's a picture of it this is sort of a stylized picture of the reactor and down at the bottom in this blue line of down the bottom of this blue line is where the sea level used to be and here's this great big wave coming up this drawing was done three days after the accident they estimated it as being 10 meters but actually we now know reliably that it was about 14 meters 45 or 6 feet and this wave came up and completely swamped everything there it came up against the buildings that went around the back of them it flooded everything and it was that flood that caused the trouble at this reactor the problem was that the turbine building that the turbine building that housed the diesel generators that there was a central power was below grade well what excuse me because below the grade of that building it was above the the sea but the tsunami swamped it and that was the cause of the accident ok so now let me go back and explain what they did they anticipated a tsunami at this site would be at the maximum size of perhaps five meters 16 or 17 feet so they built a seven-meter seawall twenty-two or three feet something like that if you build a seven-meter seawall and you get a 14 meter tsunami goes right over it never saw it hard to put in English units you build a 40 about 21 or 2 foot wall and the water it's not a wave if it's a water rise goes right over it just went right over him and and it swamp everything that was below it including all that electric power and the electric power is what caused the trouble so let me try to explain this briefly all reactors all around the world need electric power to run a whole lot of equipment and because they generate electricity it's able why don't they get it from there but they can't get it from there because you never know when you have to shut down so in fact they get electric power from the grid the earthquake not off the grid nothing surprising about that that happens all over now when the earthquake knocked off the grid the reactors behave just as they're supposed to behave everything was fine as soon as that happened the control rods blew into the reactor and shut down the chain reaction and it and it happen properly and it shut it down and everything was fine and then immediately thereafter because you need electric power every reactor has two diesel generators they actually look like those big choo-choo trains that I was familiar with when I was to get there the size from here from here to that wall these big diesel generators every reactor had two of them they had 12 of them on-site and all they needed was one or two of those to work and they could have saved everything all but one of them was totally swamped by this event one of a ram and it saved units 5 & 6 but the others didn't and that's what caused the trouble the water knocked out to these generators and now I did not have the diesel generators themselves but the diesel generators were attached to electrical wiring that had to go to the distribute that and all of that was in switch guards and all that was swamp - by the water it was all destroyed by the water and that was the cause of the accident now let me just talk about tsunami defense before I get to the you can't read this and I can't either but I but but I went to a talk by an American about this this is a Japanese slide and one on the bottom are a whole bunch of sites that go from north to south 20 50 miles north on the laughing north to south and the big red dots are the sizes of the tsunami heights and you can see the highest one way up at the top here is 27 meters which is 80 feet but there's a whole lot of them in the year between 15 and 20 meters all just all around these big red dots and as I said it at the plan itself it was about 40 meters but down below are a whole lot of different little X's and O's and stuff like that and each of those is a tsunami wall that the Japanese built some of them were at parts some of them were at little pounds some of them were at residential areas some of the various things and so they had decided they were gonna have big tsunamis and they built these tsunami walls and they were a big one some of these tsunami walls were 15 meters which is you know you can figure that almost 50 feet high more typically they were 6 and 8 meters which is you know 23 25 feet tall but you can see that just about everywhere the tsunami was bigger than they had planned more or less everywhere it wasn't the reactor that made that mistake it was the whole Japanese infrastructure made that mistake and the reactor was one of the victims of that now just before I go talk about the reactor I just want to explain something that's really important for you to understand the tsunami came 45 minutes after the earthquake they had a tsunami warning system and it worked four hundred and forty thousand people evacuated successfully during those forty five minutes 26,000 didn't it's about five percent 26,000 people lost their lives in that tsunami about ten thousand were swept to sea and they've never been heard from again and they probably won't be the others they found so a successful evacuation and 95% of the people doesn't sound like it's like they weren't prepared they just didn't get everybody some old people and some people that couldn't you imagine but nevertheless 440 thousand people got out 26,000 didn't they're dead and it was because of this failure that is shown there they just completely missed that the reactor 2 missed it I'm not placing blame here I'm just describing and that's the crucial cause of this accident and today those 440 thousand people that evacuated most of them have reoccupied their homes but there are about a hundred thousand people whose homes destroyed by the tsunami you've seen the pictures they look like pick-up sticks the game I used to play when I was a little kid about a hundred thousand people in our out of house and home and businesses and those are going to be a tremendous reconstruction job they estimate it's going to be 500 billion or 700 billion to fix that it's gonna take a long time and in the meantime what we're talking about the reactor which was bad enough but if you're if you're Japanese the true disaster is this other thing too let's not forget that now I'm gonna now switch to the reactor this is a boiling water reactor that all of the reactors at issue here are boiling water reactors there's another kind which is there more than actually than these around the world about a third of the reactors around the world are these boiling water reactors the others are so-called pressurized water reactors that have an intermediate loop but I'll just describe this in a minute what you do in a reactor is you boil water to make steam to drive a turbine and the turbine makes electricity that's how it works and the water is boiled in a great big vessel the vessels 40 feet high although the fuel itself is only 12 feet enough in height and in there the chain reaction makes the the heat boils the water folks back here the water goes around the water goes the steam the steam at the top goes out this loop on to have this little arrow that I'm sure it goes out this loop and it goes to a turbine and it spins a turbine and that's what makes it lectricity of course the generator then sends electricity out to the grid after the turbine the spent steam gets gets condensed by seawater in this case it happens to be seawater down here gets condensed back into by cold water into water again and then it gets pumped back into the reactor and goes around those and these very large pumps are what keep that whole thing going because it wouldn't it wouldn't run around the loop without and that's a normal operating reactor it's inside a great big vessel this vessels 40 feet high roughly it's eight inches or so of steel all the way around and it's inside a big containment vessel which is concrete many feet of concrete that surround the whole thing and that whole great big containment vessel is intended to keep the radioactivity inside if there's an accident I'm just going to show you a picture of the fuel because the fuel melted here and you probably the common english jargon now uses word core melt or you know i'll explain what that is the fuel in these reactors are rods twelve feet long that are about the size of my little finger well they're a little bigger maybe the size of one of my intermediate fingers they're about that size they're twelve feet long and they're arranged into Assemblies of 8x8 64 it actually says 62 because they're a couple control rods in there but it's really sixty-four of these things they're they're about that size in a box and they're these long rods and they're twelve feet long and they consist each one of them of a fuel rod made out of a metal called zirconium and zirconium is chosen because it has wonderful nuclear properties and also wonderful heat exchange properties and then the fuel itself is the uranium oxide and it looks like a little aspirin tablet a little bigger little tablets and they just get put into these rods twelve feet of them these tablets going inside the uranium oxide they're assembled into these assemblies these eight by eight they're about this big and as this one says there were 500 assembly in this big car just great big parts about the size say eight feet around and it has all these assemblies 500 each of which has 64 while 62 raw fuel rods each of which has those pellets so there are 30 says 33,000 fuel rods and I don't know how many million pellets because there a lot of them now this reactor has a chain reaction and that gets real hot in those of uranium rods very very hot and that heat heats the water that makes this team that makes the terminal but the danger in a reactor and here's where that you shouldn't need to understand this the danger is that if you don't keep that under water if the water somehow goes down the Fingal melt and the melt releases radioactivity and then the rate activity has to be contained first in the vessel later in that containment and if it isn't contained it goes out and that's a big radioactive released but it can't happen unless the car melts and the car won't melt if it's under water of course if you have a big pot full of water and there's heat you don't it'll boil so you have to even in a shutdown situation you have to keep replacing the water that boiled off in order to keep it under water in order to keep the thing safe and that's the trick in reactor safety what we do in reactor safety is make sure the systems are in place to keep it under water at all times and it has to be kept under water for years even after it's shut down when a reactor is shut down that is the control rods go in it nevertheless generates heat because of the residual radioactivity that starts out at a few percent a few days later it's down to one or two percent but even here we are four months later it's a fraction of a percent and with a reactor like this it's it's tens of thousands of kilowatts of heat being generated right now all the time from each of those reactors because of the heat is still it's the radioactive decay and you have to keep that under water and that's the thing you've got to do now let me just show you a picture for scale of the size of this thing this this is a large large one under construction Browns Ferry is in Alabama this picture was taken in the seventies and I'm just showing it to show you what the size of it is this thing in the middle is this great big containment structure that's the steel structure this large round thing that looks like a doughnut at the bottom we call that the torus it's full of water and I'll show you what its function is in a minute and just to see what the scale of this thing on the bottom here this is the cap and that big building I showed you goes on top of that so that planned view that you saw it's a huge building and just to show you the scare there there's a gal right at the top you see here right up there I don't know that that's a gal but so this is just to show you what the scale is of these things I'm now going to go to a drawing and without this you wouldn't have the feeling for what the big scale is drawing so here's the drawing oops here's a drawing this paint thing is the vessel with a fuel on the inside and as I said the fuel is only 12 feet of this 40 odd foot length and that's the steel the thing that looks like a white ball here shaped like a lightbulb is the containment structure that's made out of concrete and that's intended to keep everything inside if it's escapes from the vessel the containment structure that though is attached to this big torus it's only shown oops it's only shown here a couple of them but it says great thank you saw big it was a great big doughnut shaped thing and it's mostly full of water not completely mostly full of water and the function of that I'll come to in a minute because it's very important in accidents now the other crucial thing about this design is way up at the top of the building is a spent fuel pool it looks like an Olympic swimming pool except that it's 40 odd feet deep but it's just it's not quite as long as that but it's a huge pool because when they when they take the fuel out of the reactor they move the fuel into the spent fuel pool where it sits there for several years usually five or more underwater because it's got to be under work because otherwise it's hot and it'll boil it'll melt if it isn't under water and has to be kept under water of course it of course it boils the water a little bit so you have to keep adding new water but it doesn't boil it very much for old fuel and that's the s person spent fuel pool that's in here and that's that was that was a piece of this accident that I'm going to come to later was that one of the one of the reactors we were afraid that that's been fuel pull had been compromised too although in the in the end we learned that it wasn't so as I said this is just a stylized picture and I'm going to show you a cutaway that General Electric produced of one of these reactors just to show you how big this thing is you've got to realize this this red thing in the middle is the pressure vessel and it's 40 you saw you saw the picture of that great big thing with it I said with the woman sitting at the top well this building is bigger still and this sort of building is the picture that I showed of those reactors in Japan these are very very large structures okay and then finally way up on the top is a spent fuel pool it's in here somewhere in the sea there and here's a picture of an empty one they actually it's deceiving because this is 40 feet 47 feet deep something like that don't remember exactly they differ slightly and if that's how deep it is you can see how big it is this is a couple hundred feet around all the way around it's full of water and of course this is an empty one now let's come to the accident okay this is the normal operating configuration I showed it to stylize but this has got more detail the fuel which is stylized this red stuff in here is hot because the chain reaction is running and it boils the water in the normal operating configuration the water turns to steam and the steam is this red line going out the top eat those up here and drives a turbine turbine drives a generator makes electricity the spent steam goes down to a condenser if this gets condensed from the sea gets pumped back in goes back around the loop so the normal configuration it just goes around the loop and and these reactors where the smallest one was generating four hundred thousand kilowatts four hundred megawatts that most of them were 700 the the largest unit on that site was about a thousand megawatts these are very big power generators and as I said even when they're shut down a few percent of that is still there so what happens is the earthquake comes off they automatically shut the thing down by putting the control rods in stops the chain reaction and they're down from a full power to just a small percentage of the power so the steam in this normal configuration still does what it does but there isn't enough steam to drive the turbine so they have a bypass valve and the steam hose goes out this loop though so it goes around gets condensed and in a normal safe configuration it just stays in that loop forever as long as you want and the units that are safe units 5 & 6 on this site that's just what's going on actually I just misspoke they didn't they didn't have any fuel in them but other other reactors that that shut down that's just what goes on the trouble is that loop requires electricity there's this pump here there's the red thing has a little stylized that requires electricity to run that loop oops now they wash the grid right away immediately those large diesel generators all started I said there are two in each unit there were 12 of them on the site they all started and they produce electricity and for the first 45 minutes that worked fine a long team of tsunami knocked it out that loop doesn't work anymore oh that's what we call a blackout in a blackout situation you're in real trouble except that every reactor is designed specifically to run in a blackout situation with a special pump that doesn't require electricity and here's how it works at the next luthier the steam that's coming off of the top of the reactor goes to a steam dump but a fraction of it is glad off and actually driven to a turbine and there's a turbine driven pump driven by the steam that drives the water around in this loop and that keeps the thing full of water now let me describe how it actually works here's the steam driven pump and it doesn't show the steam line but it's this green thing it takes suction water from this great big torus that's the emergency supply and it takes the water from the torus pumps it into the reactor and and because it's boiling keeps the level up the steam on the other hand goes out a relief valve it isn't shown because at the top through a relief valve some of the steam and goes back around and it condense down in the tars so the scheme is going in the tourist of course when it's condensed the tourist is heating on this system is designed to work for several days the notion being that after several days you'll be able to restore electric power either restore Diesel's if you lost them or restore off-site power or whatever and this systems supposed to work for several days and if it does it keeps the reactor underwater and everything is fun okay and let me go to the next slide yeah okay so here's the next slide and this sort of shows of because there's a really crucial thing that all reactors have that you need to understand all of the systems that run without electricity like that system I took I showed you require batteries to control their control systems and so on and so that reactors have huge battery banks if you know what an autumn of the battery looks like we all do imagine 200 of them in a room all ganged together and imagine four or five rooms just like that batteries all over the button these great big battery that battery banks and those batteries are enough power to keep those control systems running for days that knows that's the point and therefore it you have control and you have instrumentation and readouts and you know what the pressure is and you know what that's so on so the people in the control room understand what's going on with these batteries but in fact in every one of the three reactors that got in trouble the batteries ran out before they could before they could restore power okay the reason is they couldn't restore the grid the grid was just shot because of the earthquake and they had they couldn't restore the downside diesels either but they tried to bring in off-site power but the roads were shot they couldn't bring it in and when they finally got a couple of them in they tried to hook them up these electrical systems is sort of the analog of a plug that you have to plug it in they go somewhere and those were all damaged by the tsunami so it took them almost a week before they restored electric power to these sites and as soon as the batteries ran out and as soon as these steam driven pumps failed the boiling began and a few hours later the car melted in every one of those so that's that that's what happened they lost off-site power they lost on-site power these systems work with the steam they ran on batteries the batteries ran out and when the batteries ran out they were stuck they tried all sorts of things they couldn't restore any electric power at all they actually lost readings so they didn't know what the pressure and temperature were all over the place they were just very serious difficulties trying to understand what was going on never money trying to trying to be able to manipulate valves and things because it have any power at all and that all happened because they didn't have enough time to restore any power because the earthquake had caused so much chaos they couldn't bring in things and there was a whole lot just a whole lot of failures one after the other cascading things that sort of puzzle lost you would have thought I would have thought that somewhere along the line for each of those three damaged units they would have been able to restore something but they did so here's what happened unit 1 for example unit 2 unit 3 they were the three that were running in each case in at different times when it happened for for one of the units for example this steam driven pump ran for almost three days for another one I ran for less than a day and for unit one there's a little different system and it only lasted about eight hours as soon as you lose that the steam the it's steaming you're losing water you can't replace it the level comes down and after the level comes down the core becomes uncovered I showed you the picture of those rods the core becomes uncovered and as soon as the core becomes uncovered you get into real trouble and here's why because the things are very very hot when they're not under water and the hot water isn't taking it away and all the fuel is clad in a zirconium planning this metal sheath that I showed you it's about the size of your finger with a little uranium inside and that's our cone ium which is a wonderful has wonderful properties otherwise will oxidize when they in the presence of steam and here's what the reaction is for those chemists in the room it's a simple reaction there's there's it's coming down and then steam does echo neum reacts for the steam you can see the reaction h2o but that steam produces the corneum oxide and hydrogen now what's troubling about this is this is an exothermic reaction that is every one every one of these that goes every molecule that happens releases energy so it makes it even more energetic and it drives the reaction that goes as soon as it gets started you can't stop it unless you put water in there it doesn't slow itself down it actually it actually speeds itself up and this happens above about twenty-two hundred degrees Fahrenheit and ultimately by the way it gets hot enough to the uranium which is now a eutectic with a metal and stuff it finally melts in a very hot temperature of 48 hundred degrees that's a really hot temperature okay but that happened here in all three of those units water came down the zirconium water reaction steam reaction made oxide and hydrogen zirconium went away kept heating up the uranium finally got hotter but by the way without the cladding it sort of falls down into a what I would call a rubble bed it looks like a pile of you know these little pellets at the bottom of the reactor and of course it continues to boil off and finally you get something like this this is a very stylized picture but this is the idea you have this core debris in the bottom of the lower head of that vessel and this is tons and tons and tons of this stuff I can't remember how many I should remember but I can't probably remember and it gets at the bottom of the vessel and it's hotter than a pistol in fact as it heats up this is shown when it's still not hot enough to melt but as it heats up finally the uranium starts to melt and we call that sort of a khorium it's a it's a it's a this is a hot molten liquid here with just a little bit along the bottom and it'll it'll melt it'll just all that we'll know if there's no water to take away the heater no way to take away the heat and that's just what happened in these reactors so let me go back up this reaction takes place it melts it all falls at the bottom and it's hotter than this it's very very you have no idea what 4,800 Fahrenheit is it's just incredibly hot and there's hydrogen that has evolved into this this pressure vessel from that reaction I told you about the hydrogen over pressures over pressurizes the reactor let me go up and show you that it over pressurizes this the inner reactor vessel so there's a release valve and the hydrogen goes out the relief valve but by now there are radioactive gas releases to it it also goes out the relief valve and the hydrogen and the radioactive gases are going out that relief valve at the top of this vessel and there's a pipe that takes them down and brings them to this great big torus this great big donut suppression pool where they're directed so that they will get dissolved in that water as long as it's there and keep it from being released and that's a design in which the exhaust gases in the case of a very remote accident like this go down to the torus this big donut and they're supposed to be condensed at least for as long as you can as it'll work and that actually as best we can tell worked but ultimately because they couldn't restore water and they didn't ultimately what happened was this whole great big black thing on this on this drawing this whole great big containment got over pressured by that by the gases and by the hydrogen and by the way various other of a gas is a whole lot of a whole lot of heat and overpressure and this great big thing got over pressured the reactor operators seeing that decided that the way to save this whole thing from losing that which is a very important vessel was to relieve those gases so there's a relief valve straight to the outside relieve you to the outside and what they want to do is relieve radioactive gases it's not a lot of it but it's someone it leave radioactive gases and hydrogen to the outside to save the pressure in there otherwise that you otherwise you'd get in trouble you lose the whole thing and then you got a much worse mess so they decided to do that but it turned out it was against their procedures excuse me I misspoke they didn't have written procedures for that process everything else before this they had procedures even for these unusual accidents but they didn't have a procedure written down that enabled them to release those radioactive gases to the environment out that staff they had to ask permission of their headquarters in Tokyo four hours later they kind of thought gee we better do that but they didn't do it themselves they decided to ask the government took three more hours and there was a seven hour delay between when the operators in the control room decided they had to do that to save this thing and when they finally got permission to do it during which time a whole lot more pressure and a whole lot more trouble ensued and and a lot more damage took place and I'm going to come back later to why I think that's that that just doesn't make any sense that decision process but that's what happened and finally finally they did and they released this this the pressure that's in this this great big black thing here to the stack and was supposed to go out to the outside but something failed and it didn't go to the outside we don't know why to this day all three of them this failed instead it got released to the reactor building and the gases ended up in this space up on top above the reactor but inside that building and that's a lot of hydrogen and one after the other that unit one exploded because hydrogen is explosive all you need is a small spark and the DOE explode the unit three hydrogen exploded and you know - it didn't explode because there was a hole in the side of the building about the size of a window and it escaped and save that building I'll show you a picture later in which that building is it's okay even though the other two explode it so they had these hydrogen explosions because that valve that relief valve system didn't work and we don't understand that this day why it didn't work so that's it there are several failures here where we engineers don't understand why I failed or how it failed I'll just explain then that that when that roof blew off they had a whole lot of radioactive releases and that's what caused the contamination of the countryside well there was water contamination - I guess I'll come to that in a minute so let me go down so here's this picture again showing that and now I'm gonna keep going and I'm going to show you a picture of what what these buildings look like here's the unit - you remember how big these buildings are that picture I showed you that was inside this thing these are big buildings these are ten stories high there's a picture of a right here in the unit - of a window sized hole that vented this thing so that the roof didn't blow off of it but unit one blew off unit three blew off unit 4 blew off and I'm going to come to that later to try to explain why because we're still puzzle about how that happened because there was no fuel in the reactor there and we're still not sure how that happened and although I'll come to it later and try to explain it so these big explosions blew the roof off and and of course a lot more stuff was released it wouldn't have been let me keep going down here I'm gonna I'm gonna go back to my picture here because I'm going to tell you a couple more things those radioactive releases occurred on the second day and on the third day and the wind was blowing from the ocean northwest and that's where the contamination is I'll show you a map of that in a minute and that was what the gaseous release was you should know that the gaseous release was depending on it was units one two and three I'm the average about five percent of the rare radioactivity went out to get when it went out airborne the one unit was four percent when you were six percent was five roughly five percent about one percent was a water pathway and then explained in a minute and the rest of that almost 95% is still in those vessels I'll just go back and show you to still look either this or this we're not sure but they're still in the vessels and it's really important that they stay in those vessels because if they stay in those vessels they're not going anywhere and if they can stay on those vessels for years it's great now if they don't stay in the vessel they're gonna leak into this big containment thing well that's okay too but we'd much rather have in the vessel and for at least a month probably a month and a half the engineering community around the world and I was part of it and the u.s. helping them with advice and trying to figure out what to do and what reactions might take place and so on we were trying to figure out how to make absolutely sure that they could keep the stuff in the vessel where it remains which is great now one other thing has to do with sea water after the in each case after the course started to melt and they had no water to put in there they decided that gee they should try to inject seawater because the oceans right there because they didn't have any other source of water so if you and Jeff see water it's a terrible mess it was outside their procedure so again they had to ask headquarters and they had to ask Tokyo that the company took the electric power they had to ask the government and many hours later they got permission to in jeff seawater and all three of those put seawater in there and to fill the thing up and stopped stopped whatever was going on and stabilized it and that was great but they actually waited many hours to do that while they made a decision process that involved the people in in headquarters and in one of the units the control room operator actually decided to overrule what headquarters was telling him to wait and he did it without him violating his procedures you know putting his life and his pension at risk you just imagine I mean but he did it and he actually made one of them saved it in the sense that it's far less release than he would have had if he had wait for wait for permission now let me try to describe why that's a problem it should be obvious to you I'm almost done here when you're flying an airplane you know we all know the pilot has the authority to do whatever is necessary to save the plane they get on the phone they talk to people they get advice they tell you know it's wonderful but in the end the pockets got the authority to save whatever to save the plane in our reactors that control room chief has that authority doesn't you can ask anybody for advice but he's got the authority and in Japan they don't it's not in a written procedure they don't have the authority to do it and they didn't do it and that's an institutional failing of the first order and we knew this a day or two after it happened but on our side of the ocean none of us said anything about it because the last thing we wanted to do was to be accusing them and causing them to clam up and not not not offering information and so on and finally a couple months later they owned up to it in public and now we're going off and we're saying it - they've said in public boy that was really a dumb arrangement and they fixed it we hope but that's a real difficult institutional problem not a tactical about an institutional problem about how they ran their control said that growing their reactors because they could have saved a lot a lot of things here had the people in control room have that authority okay now let's talk about the waterborne pathway every one of these big vessels has - you can see them here in blue two loops with pumps on them which are called recirculation loops that that pump water around the vessel just to stir it up - so it doesn't stratify and and these things are huge those these blue lines that you see here the valves are about a beat the the flange is about a meter around I mean you're three feet around they're huge like this and they're not supposed to leak but in fact in this core damage accident they leaked and the water went out here went out another one here went into the turbine building went into a Trench and went into the ocean and that's where the water came up in our reactors we think our design shouldn't do that but we're still not sure whether that's so and until we do city we'd they together do some examination we're not sure whether there's some flaw in our design too that would cause this to happen in our designs and if that's true we're gonna have to fix it if it's only there as we all will learn that - about 1% of the radioactivity went out through the water went into the ocean as you probably know contaminated the ocean it's contaminating wildlife there it hasn't reached the fish yet because you know it first has to get to the algae and little fish by the time it gets to the fish it takes a long time but they're monitoring at all and nobody's eating any fish and in the meantime it's a huge financial disaster but it only was about 1% of the radioactivity just think how much worse it would have been it had been much greater than that so the water borne pathway was that was the failure of these flanges the airborne was the failure of that it heated up and went out the step so so there's a succession of problems here and I'll just go over them before I talk about the other implications well I'll just go down here leave that up first was they never should have put it at the site they put it because that tsunami was just overwhelming the reactors just three or four miles down the coast they were immune from the tsunami they came out fine even with this huge earthquake so that was the first thing we don't understand that I'm not sure they understand it either but that's that's obvious in retrospect it turns out we don't have any reactors like that in the country that are here we have reactors in California along the coast but they're high and dry and there's no tsunami problem there anything like that we don't understand that especially when looking back at the records they had huge tsunamis like this every few hundred years along that coast in their 2000 year history they had three or maybe even four of them it's hard to know it's hazy way back in history but they had at least three of them there were this big and so they should have known that secondly they had a blackout they lost the on-site power after they lost offsite car because the diesels were underwater if they have been the roof that would have been fine thirdly they had that steam-driven system and that should have worked we don't understand why it doesn't work that to this day it's a bunch of engineers like me and I know those systems intimately and we don't understand why they didn't last for days rather than only hours and where we don't think it says it's a problem that the earth may cause that trouble because they ran for a long time and besides they've been shakin on shaker tables and they're very strong against earthquakes so we don't really understand that okay one last thing I'm gonna go back up here unit four didn't have any fuel in the reactor the fuel was in the spent fuel pool so the hydrogen explosion that blew off that roof couldn't have come from the fuel in the reactor for the first month we the community of experts we were sure that that was because the spent fuel pool had somehow lost cooling it was a fresh car remember just had been offloaded it and it generated hydrogen from that but finally six weeks later the Japanese went in and looked and it's fine it's full of water and there's no radioactivity it wasn't that so how did this hydrogen get over here well there's a pipe that goes from unit three to a stack to unit four and as best we can tell it went across this this pipe although we can't understand why it should've but it must uh and filled up this building and we had an explosion over there and it seems very very unlikely there are check valves and they're very strong and we don't understand it but there's no other explanation in fact I'm fond of saying something that perhaps you remember Sherlock Holmes once said that if you ruled out all the impossible things then the really unlikely thing is it well this is really unlikely we just don't think but it's but it's got to be so they had an explosion over there that we thought was the spent fuel pool now we know it is and it hadn't been hydrogen that came across from you know three two uniformed blew that thing up let me keep going back over here I'm going the other way so here's where I was having explained all of these problems I'm going to try to talk about what the global implications are for a minute and then talk about about the United States the global implications are still unclear it could be that the flaws here are fundamental engineering problems that plague all of the reactors everywhere we don't know that yet if that's true we're gonna have some very serious either shutting down and that's--it's or maybe something can't run we're not sure I'm in a community of people that are looking at this real hard it's probably going to be a while before we know because it's gonna be a while before we can go in and inspect but it could be that it's dumb if you don't mind saying hey to say that but but an easy fix in which case we'll do that we don't know it's a real come up and for somebody like me I've spent you know decades working in this field we have fought through a whole lot of things we thought we have thought through this sort of accident and it happened anyway and we don't know why and that's it's humbling by the way it's it's kind of in a macabre way it's exciting to be involved in trying to figure this out but it's really my job because all those people died and we don't know why this accident happened and so on okay so we're still the community is still sorting this out and it's probably going to be a while before we do in the meantime I'm going to come to the American situation now and tell you what we're doing here it's just so you'll understand now here's a map of the US with all of our reactors we have 104 reactors operating now 23 of them are basically identical to the ones that Fukushima they're plugging water reactors of the mark 1 design there 104 altogether and the rest of them are similar but different they're mostly in the east as you can see I live in California where there are four of them three in Arizona the rest of them are in the east and I'm sure you know where the ones are annoying when there's one in Vermont there was one up here in Rome only 35 miles from here but it's been shut down for a decade there's there's one south of Boston is Connecticut and so on and all of these are doing something right now which is going on which we hope is going to at least teach us some of the lessons here and that is every one of them is looking at the things that they're reactor that we already know about and seeing whether or not they are so for them or not and all those reports are due pretty soon but so far as best we can tell none of the reactions have uncovered any of the problems with engineering design that plagued the Japanese as best we can tell and that's good news if it turns out to be true in the end we don't know that it's true in the end but we're gonna find out it'll probably be awhile before we've tracked it all down and after they get in there and clean the thing up they're going to be some more engineering problems we're gonna have to track them down and there may be some fixes but so far it doesn't look like like any of this is plaguing us our reactors can survive a blackout for a much longer time than that at least they were supposed to - although those things failed and we don't know why yet so we're gonna we're going to get to the bottom of that next I'm going to talk about radioactivity because I'm going to explain what the significance was of the releases I have to talk about the average dose to people in the United States and this is true in Japan also the average person you and me and everybody else here not counting medical radiation we all get between two and 300 milligram per year milling Ram is a unit of radiation dose and a lot of it comes from the rocks in the soil that we live on and so it varies a lot from grief here in the Berkshires you get more than if you're along the coast and there's some cosmic radiation and if you move to Denver you get a lot more because that's it's higher and there's more in the rocks and more cosmic radiation we had a granddaughter living in Boulder for a while in Colorado and up there instead of about 300 they get about twice that so the natural sources of radioactivity and a little bit from consumer products are about 300 million per year or 200 varies and on average in the United States and this is true in every advanced country like Japan there's another 300 or so that comes from medical not everybody gets it I mean I did I had some last year and the year before I didn't but the average is people get about another 300 milligram and on average in the United States somebody just a normal citizen gets about 600 as it says 620 and now I want you to keep those milligram in mind but for because I'm about to describe the impact on Japan okay and they're about the same and by the way nobody thinks that six hundred milligram is a terrible health hazard because when people look and study and I said you moved to Denver you get twice as much and you study that you move to higher elevations get even more studies haven't shown any any observable effects there's some suspicion there maybe something if there they must be very small because they never seen anything from this it takes much higher doses than that to cause trouble now here's a map of Japan this was taken in early April and these blue lines are just slight patterns of an American plane that was flying measuring an airborne radar cake but that's not the point of the slide there's that red dot is where the reactors are and the first circle is 20 kilometers 12 miles the next circle is 30 kilometers about 19 miles and the biggest circle is 80 climbers about 50 miles so these are 12 about 20 and about 50 mile circles around the reactor site and this this these measurements were made three weeks after the accident but it's about the same and when the releases occurred the wind was blowing from Southeast to Northwest and the big contamination in a zone here that you can see it's yellow and sort of orange up here and it extends about 20 miles out from the reactor site and is about 3 or 4 miles wide and that's where the contamination is bit everybody's been evacuated from this whole area but in that area they're not going to be able to reoccupy that for a long time probably they're going to have to take down all the houses and cover those in Holloway and build a new in there there are 40 odd thousand people affected by that in these other areas they're going to be able to reoccupy maybe there may be a few hotspots there measure and one by one and make sure but the other areas they'll reoccupy although they did evacuate much larger and the area that's sort of in blue out here is real real low that's that's elevated compared to background but it's more like twice so it's sort of like living in Denver and nobody nobody nobody thinks that's big so the area of contamination is in a zone that is like I showed now the Japanese have adopted the following criteria if the dose in a year is 2000 milligram you can't go back it's less you can now remember that the natural background about six hundred three hundred and another 300 for medical and I said people that people in the Rocky Mountains get you know eight or nine hundred they've decided that two thousand is their criterion and higher than that they can't they're going to clean it up and that zone with 45,000 people extends about 20 miles out in 3 or 4 miles wide as you can see on this map ok people outside that zone may have there may be case-by-case they have to do some cleanup but most of it will be ok now the first three miles were all destroyed by the tsunami but outside that the houses are fine they're just they look fine they're contaminated with radioactivity they look fine so if they can clean them up perhaps they don't have to take them down they're doing a lot of work now to try to figure out what to do in the meantime those 40,000 people I've been evacuated and they're living in temporary shelter and there by the way the businesses and some of its farms and so on but there's one saving grace and that has to do with the discipline of the Japanese and it would be true here also nobody in the public gotten any exposures that mattered here and the reason is they evacuated right away and they evacuate except for them I mean they're back from the radioactivity you know they have two days to do that I'm not talking about the tsunami evacuation but the people that were left they evacuated for the radioactivity before it was released no member of the public has gotten any any any radioactivity to speak up because they've all been evacuated I mean it's contaminated the area but not the people they're measuring the water they're measuring the food some of its contaminated nobody's eating it they're measuring the fish not much yet maybe later no one's eating it so even though the economic impact is huge as best we can tell because of the discipline there interdicting all that matters and no one in the public is getting anything radioactive and that's a terrific statement about their discipline and being able to make the measurements and you know people paying attention so that's good unfortunately there were several people in the plant that got serious doses to at least that got really serious radioactive doses looks looks we're not sure yet I'm not an expert and another 10 or 15 that got doses that they shouldn't got that probably they won't lead to disease they don't really know and they're they're going to follow them so there were a few people in the plant site that got radioactive doses that are tragic and we hope which didn't happen but I want to put this in the context of 26,000 people lost their lives in the tsunami okay just don't forget that finally and I'll just leave you with this thought we have like the Japanese evacuation plans for all of our reactors and theirs they did it and it worked I'm talk about the radioactive one you know they they had to several did a couple days anyway and they got him out that tsunami they only had 45 minutes didn't get everybody out but for the radioactive they got everybody out there was no there there was no problem that and we have those two around all of our reactors as perhaps you know and they do training and we have confidence if something like this happened in one of our reactors we get them out too it would be a terrible contamination disaster and a big economic loss but we don't think that that these people are we're we're not protected I'm gonna close just with the economic impact and then I'll stop and ask you forgive me if you have any questions the economic impact is as follows to clean up the radioactive contamination in this zone is thought to be between twenty thirty to forty billion dollars it's a lot of money to clean up the reactors and very all that stuff a few years hence is going to be ten or so billion maybe twenty they're not sure ten or twenty for the reactors twenty thirty forty for that the tsunami cleanup is five hundred six hundred perhaps even eight hundred billion and remember twenty six thousand already died so as big as the reactor is economic impact it pales compared to the impact of that is enough I'll just leave you with that thought we've got to remember that we're talking about the reactor because that's what everybody's interested in that's what I do for a living but the failure here the societal failure here was their failure to understand how big that tsunami might hit them and their failure to protect against it the reactor failure with some engineering things that we're getting to the bottom of and we will someday know more than we do know and we're either going to shut them down and fix them or maybe have to shut them down entirely we just don't know okay thank you very much I'm a dancer you

Channel: WilliamsCollege

Views: 20,215

Rating: 4.2421055 out of 5

Keywords: Robert Budnitz, Fukushima, williams college

Id: 4z7OwfwoPzA

Length: 59min 48sec (3588 seconds)

Published: Thu Jul 21 2011