How Bad is the Reactor Meltdown in Fukushima, Japan? ▸ KITP Public Lecture by Benjamin Monreal

good thank you David so I'm not going to attempt to answer all of your questions because there's not there's not time in particular I'm not going to attempt to to discuss how reactors are supposed to work reactors are supposed to do a certain thing and they're supposed to produce power in a certain way and they're supposed to regulate that power in certain ways they're supposed to not blow up and that's that's a little irrelevant now so I'm just going to leave it aside in the case of Fukushima the thing that's relevant now is that these reactors are leaking radioactivity radioactivity is very scary thing for many people and that's what's I think that's what's important in the near term that's it's important for the people that it can and many people are concerned about whether it whether or not it's important for us so the main thing I want to talk about is what is the radioactivity that's coming out of these reactors why is it in there to begin with how does it affect you if it gets to you and and and how does it get to you how does get out and we'll talk about the implications of some of that so this this is a I recognize there's a bunch of actual physicists in the audience this is this is not a talk for physicists this is a talk for the general public physicists have their own ways of figuring out what a micro sievert is so to understand where radioactivity is going we have to look at different radioactive elements and you know different radioactive elements are going to behave different ways depending on their chemical properties so this this should be familiar to you because this is the table used by the California Department of Education hydrogen helium lithium beryllium boron carbon nitrogen oxygen and so on all the way up to uranium plutonium and some of the elements that you'll be hearing about in the news on a regular basis are things like iodine cesium tritium and the reason you're hearing about them is not that iodine is inherently dangerous you've probably dealt with iodine in your high school chemistry labs but there are isotopes of iodine that behave just like regular iodine except that they're radioactive likewise for hydrogen there's an isotope of hydrogen which is radioactive and fairly hazardous and so cesium but in terms of understanding what they do that's that's a job for that's a job for chemistry and so we'll be going back and forth between the nuclear side and the chemical side for the nuclear side why is some hydrogen safe another hydrogen dangerous well the thing that defines it is Hydra is that it has just one proton and therefore one electron that's that's what gives it the chemistry that you associate with hydrogen that's what makes it able to go into h2o this kind of thing but that doesn't define the number of neutrons you can take that one proton and have it all by itself in which case it's the hydrogen that you mostly know and love or you can add a neutron to it or you can add two neutrons to it then it becomes radioactive that doesn't change the chemistry at all it still behaves like hydrogen so in order to understand the radioactive side of it we have to go to a different graph where we have a place to put the neutron number so what I'm going to show you now is we're gonna unwrap this and just list the elements in order on the vertical axis so here is hydrogen helium lithium beryllium boron carbon nitrogen oxygen stack them up there's no periodic nough Sabattus we're just gonna list them in order and that that's the number of protons and in this axis we're gonna represent the number of neutrons so hydrogen can normal hydrogen H one is just one proton all by itself H two is what happens when you add a neutron so hydrogen two is also known as deuterium both of these are drawn in black because they're stable they're safe they're not radioactive elements if you add that third Neutron we change color the green representing radioactivity tritium is a ch3 it's got two neutrons and one proton adding up to three that's what this number is the total it's a it's a heavy isotope of hydrogen it is radioactive the same sort of pattern is true of everything in the periodic table all of these nice familiar happy elements like helium lithium beryllium have the safe familiar elements this a familiar isotopes that you're that you've seen before but if you add a couple of neutrons to them you get this this short-lived radioactive stuff that that's going to emit particles it decays it also happens if you remove neutrons from them you get other radioactive particles but that's almost totally irrelevant here those are very rare in nature but here's this this line of stability we're gonna we're gonna zoom in on this in a couple of different ways one thing to look at is is where do things decay when tritium decays this is a ch3 that tritium it goes to helium-3 it just wants to change a proton into a neutron sorry it changes a neutron into a proton because it is remember all this stuff has too many neutrons it's all Neutron rich yeah I'm gonna zoom out again so here's that same chart hydrogen helium lithium beryllium boron carbon nitrogen oxygen fluorine neon Sun vanadium and so on and uranium will be up there somewhere and here's that vast universe of either short-lived radioactive or less short-lived radioactive and then here's this nice line of stable stuff so anything that you could possibly manufacture over here is going to be radioactive in some way and if you make it it's going to decay by going hop hop hop hop until it gets to something stable this is the majority of the radiation you're hearing about already at the Fukushima reactor accident it may mean it may not be the majority the radiation that you hear about in the future depending on how how fires and things go I'm gonna zoom out one more time to show you the whole table so this is practically every nuclide we've ever seen in nature were made in a lab ranging from hydrogen way down here in the corner there is hydrogen - there's deuterium tritium and you stack them up all the way here until you get to lead so that's the valley of stability those are all the stable isotopes and that's the vast majority of what you experience in daily life for these there's black line running up the middle of this thing if you have lots of protons you generally have to have lots of neutrons the relationships not quite one-to-one it's not one Neutron for protons over here it's more like one point - excuse me so you look up here there's something funny going on up here this is actually this is a very interesting region of the chart because I said this is hydrogen through lead maybe business depending how you're counting there's a gap of nothing stable and then suddenly either's uranium thorium lutonium the the fuel for reactors this is stuff that's stable enough that Nature has given us big piles of it there is there is a lot of uranium on earth it's actually not uncommon at all and it's been sitting around since the since the birth of the planet you know four billion years ago actually have a bit of it here here it is this is a bit of uranium ore very very low-level this is I think a killer Becker l or so I'll explain what that unit is in a minute and then that'll explain why I'm not afraid of it in this case in this case so what you do when you're building a reactor is you dig up a bunch of uranium you put it in the box and there's some complications it's the synth and then you try to make it fission which means you hit it with neutrons in the brushing every possible detail on the drug fissioning a uranium atom is splitting it in half you take this one giant nucleus you kind of make it go bleb in the middle and splits into two big nuclei not of exactly the same size there's usually a bigger one and a smaller one and there's often a couple of neutrons that pop out too but for the most part you're dividing the protons the neutrons in half and you're making two things with half the neutrons and half the protons but look if you divide these numbers in half in following a straight line down here you don't end up on the stable line fission does not produce stable isotopes immediately it produces very Neutron rich isotopes often very very neutral some of them you know some of the richest Neutron things you can make outside of a very specialized circumstances so when you're running a fission reactor this is what you want to do this is where you get all your power and this is where you get a bunch of radioactive waste it doesn't stay there forever because remember this stuff's all unstable and unstable means it decays which means it moves that way moves back to the line of stability over various time scales sometimes seconds sometimes years sometimes thousands of years and once once those nuclei have reached the line of stability they're stable stable nuclei just like the ones you're used to indeed most of the nuclei that you're made of let's see let me correct that most of the nuclei in your body or in your environment that are heavier than iron at one point in their history were some horrible radioactive thing on this side of the chart all of the gold in your wedding ring was you know four billion years ago was a pile of radioactive iridium and and then it decayed into gold so these products are really perfectly safe once they've decayed the problem is getting in there so that's the reactors job that's that's where you get all the power from it's where you get most of the power from about 95% of your power comes from that fission process and then another five percent comes from the the final the final walking back slowly to the to the line of of stable isotopes the other thing to note remember that this axis of the chart was hydrogen helium lithium and so on up to uranium up here so when I draw these blobs that spans a whole lot of elements that everything almost everything from Krypton up to up to what gadda lynnium or something so there's a vast swath of the periodic table represented chemically here so if you want to you know control these things chemically you have to know what they are they're everything there's all kinds of materials in here so that's some of the radioactivity of a reactor not all of it the other thing you have is that uranium and plutonium and whatever is sitting there in your reactor core the stuff that you wanted to fission doesn't all fission sometimes the uranium atom will capture a nucleus and not fission which changes it from uranium into something else which then decays and you can capture Neutron to that and so there's a bunch of neutrons shuffling around that happens up here and I'll let Neutron capture on fuel I don't know what what it's called technically and you end up with kind of a smear of stuff in the vicinity of uranium and that piles up and you're after that's mostly what we call minor actinides also radioactive because that's all you know it's not those couple of nice black stable dots in the uranium area it's all the stuff around it because the neutrons truffled things from place to place the third way of getting radiation radioactivity in a reactor context is that you have all these neutrons flying around they don't just hit the uranium they also hit you know the steel and the water and the nitrogen and everything else so Neutron capture on other materials can make a bunch of induced radioactivity and if you're actually working in a nuclear power plant we're working in a radiation environment generally this is what this is what gives you most of your headaches because this is this is kind of on things that that you're not normally being very far away from you know if your pump is radioactive if your your valves are radioactive it's because of stuff like this and that that takes a lot of work but it's not most the radioactivity most of the radioactivity that's actually in the fuel is in this stuff up here and that radioactivity can is releasing energy we want it to release energy because we want power from this from this fission process but let's look at how that energy is released and and understand how its harmful there are there are basically two kinds of radiation damage that we worry about when we encounter radioactive elements there's alpha decay and there's there's beta gamma decay if you're at Chernobyl you also worry about neutrons but we're not eternal and the Fukushima should not be a bin of neutrons anymore so here's here's a nucleus nice big fat one 2:22 radon it sits up there with the minor actinides although it's not technically an actinide if this is what this is something we encountered very commonly in in research context and when it decays it does this let me see if I animation works it spits out a helium four nucleus commonly called an alpha particle but it really it's just a helium four nucleus two protons two neutrons and that nucleus is a highly charged it's moving fairly fast but not super fast and it turns out that gives it a very high probability of damaging anything it passes so I've it's crashed into my label up here so a good way to if you want a pretty good estimate of what happens when an alpha particle goes through your body which would happen if you had some radon sitting on your in your lungs or in your skin draw a line from that particle count every tenth atom that that line goes through every tenth atom is going to be altered in some way be ionized could be could have a chemical bond broken returned from a nice stable thing into a free radical so that's one of the that's one of the ways the radiation damage happens and it happens all in a in a clump the Alpha stops pretty fast lots of damage in a short distance it also doesn't go that far because it's it's wasting all its energy on every tenth atom the other kind of decay that we worry about is is relevant for fission products particularly which is beta k beta decay so here's a carbon-14 nucleus carbon-14 is a little to the right you're right of the this line is two beliefs if it has too many neutrons it wants to get rid of one it's going to do that by turning a neutron into a proton and emitting an electron and it saddens me to say this but this is it also emits a neutrino and if there weren't reactors blowing up I'd be spending all my time studying neutrinos but and it really pains me to say this ignore the neutrino it doesn't do anything we have to we have to pay attention to the electron the electron is what's coming out of this thing really fast and it has all these interactions so it's going to crash into stuff and damage it that's beta radioactivity and that is the majority that's a very large substantial part of what you get from fission products beta decays do not damage everything they pass they're not as as interactive south of particles whoo I don't know what the word is rough estimate every every thousandth or 3000th particle along the path of the beta will be ionized chemical bonds broken that kind of thing so those are those are the forms of radio right radiation damage gamma decay is something that looks from a nuclear physics standpoint looks totally different than beta decay it's just an excited nucleus D exciting from a radiation safety point of view it looks exactly like beta decay because there are nucleus D excites and a gamma ray comes out it hits an electron and thereafter the electron looks just like this one so beta gamma from a radiation safety standpoint exact same thing but the nuclear physics this is much more interesting on on one side so how much damage how much damage do you get this is this is where this is this is my radiation numeracy lecture to understand radiation you need to understand radiation units and they're a mess these are the worst units in all of physics I mean you what you want stat coulombs I'll give you stat coulombs this is terrible how much damage do you expect from a given amount of radiation there are lots of different ways to measure that and you will see all of them in the New York Times I think I've seen all these in in the in the news in the past couple of days a Becker L is just it's just a count how many decays are happening per second it's like 1 Hertz in radioactivity units so one decay per second that means you've got a better well this thing I just put in my pocket is probably about a kilo Becker L kilo is a thousand so that's a thousand decays per second little little lump of very weak uranium ore I'll take it out of my pocket and that's that's a useful unit for something's a curie is the same thing just multiplied by 37 billion and you will see you'll see both these units Becker L is very frequently expressed when you're when you're looking at radioactive fallout people say oh there's there's a killer Becker l per square meter of cesium on the ground that's an amount you could if you wanted to if you could take that number and the half-life and some other stuff you could turn that into grams or moles or kilograms or anything any of those sort of amount units that you're used to this this is a quote from a recent times are told there are 20 millions of Curie 20 million Curie's of cesium 137 in the fuel pond that's the kind of thing you'll see that's not useful for thinking about hazards well it's it there are a bunch of steps before you can think about hazards from from Curie's thinking about hazards you want to know you know you say I don't care well how much radiation it is what I want to know is how many chemical bonds in my body were broken so we've got this unit called the gray which is let's see this is this is how I translated it this morning this sounds confusing now if you imagine having a billion u-238 decays per gram of your body sounds like a lot right that's that's a gray so a gray sounds like a large number for starters cesium is a set so that's an alpha decay this is a beta decay it's one of those electron ones it's a weaker decay so 10 billion cesium 137 decays would also be a gray and that's per gram so you can even get a gray in your hand or you can get a gray in your thyroid you can get a gray on your whole body depending on what the dose is depending on what's going on and that's it's really a pretty good count of just how many bonds were broken total a complication is that some some bond breaking is more effective at damaging say DNA an alpha particle is a much better tool for smashing up DNA molecules than a beta particle so we came up with this other unit which is the same thing as a gray except that you count alpha particles factor of 20 higher so if you want to translate it into number of decays it looks like this again per gram of body mass and so think of this is how many bonds were broken in my body what fraction of my body's bonds were broken maybe and think of this as what fraction of my body is DNA molecules were damaged because they're they're weighted differently and so with that introduction when we were talking about fission products they're the same thing so forget all this but you'll you'll see both of them at a time so I mean translate one to the other notice this is a this is a decays per second this is just a total this is a this is a integrated amount now I'll give you an example of this is this is joules per kilogram in physics terms the and so the what you want to have is some intuition for which of these are bad which are less bad a Curie is a carry a big number and a curie of tritium I would I would happily put in a test tube in my pocket it's not that much a curie of strontium-90 i would not stand across the room from that curious the different things can be scary you're not scary this is not the most useful unit useful unit for figuring out what's scary and what's not or the gray and the secrets let's go on to that so you were all getting irradiated right now and it's not the fault of my uranium if you if you eaten a banana recently you've got you've got some potassium 40 in your body it's just a natural component of all potassium your dose from a normal body load of potassium is about 0.2 millisieverts per year nobody remembers what a milli is it's a one one thousandth so a thousandth of a sievert per year you're getting just from your own potassium some of which is radioactive yeah Matt okay a beta gamma are there the air around us has some radon-222 in it that's an alpha decay some times that radon is drifting around the air will find itself in your lungs at the moment when it's decaying that's about a millisievert per year for all of you cosmic rays are raining down on us from the upper atmosphere muons passing through your whole body nice straight lines beautiful particles about there the bottom millisievert per year move to Denver you can double that higher altitude are you a flight attendant you can multiply that by another another factor of two or so you're again you're above the atmosphere all this time you're getting extra radiation so I mean if a friend of yours tells you that they're moving to Denver you don't say oh my god you're gonna get an extra millisievert so this and as well you shouldn't so this is so this is part of the radiation numeracy a few millisieverts is not really worth worrying about it's it's just it's not something that we've seen that we have any evidence for harm for and it's something that we tolerate huge variations in in in daily life this is a plot they got from a photograph from a book these these are natural backgrounds in in some horrible unit oh yeah this is so these these are don't worry about this but this is you know if you live in the UK you're your total dose is about 1.5 millisieverts per year if you live in Finland it's about seven so if you're if you're not terrified by that difference you shouldn't be terrified by some other source of a messy room so what let's looked at look at something scarier which is a sievert sieverts a thousand times that the thing i told you you should ignore so with when we get to Seibert scales we're talking about may be worrying about risk of cancer cancer firmly radiation how is it cancer well you get this ionization which sometimes not every particle to do this but once in a while a radioactive particle will happen to hit some DNA and damage it sometimes when DNA is damaged the cell can't repair it and it does something it's a useful part of the DNA and so it changes the way the cell behaves sometimes when this is the behavior of the cell has changed instead of is the cell dying which is probably more common sometimes as hell becomes cancer so that's how you turn you can turn billions and billions of ionization events very rarely leads to cancer and that the numbers I could find on that are there this this is actually this is a very interesting set one sievert of dose given to a thousand people so a thousand people ten thousand people getting a sievert each look at the here's a list of cancers and here's how many extra cancer diagnoses there would be per year in that ten thousand people and I'm the extra diagnoses per year now remember there's already radiation in our radiation there are lots of diagnosis of leukemia breast cancer thyroid cancer these are the extra ones leukemia three extra cases breast cancers have an extra cases thyroid cancer 1.5 X cases stomach cancer five extra cases now that's that's not insubstantial risk but nor is it you've just dropped dead I was trying to find something to compare this to and I'm not sure I have the numbers exactly right there's not good data on this but I think that's about the same risk as texting while driving if you're if you habitually send you know SMS messages while driving you are accepting a risk comparable to a sievert of radiation so let's think about so compare this to a millisievert a seabird is something that you would go that you should go quite out of your way to avoid but doesn't it doesn't drop you dead on the spot nor does it just give you cancer on the spot I should add there so there's a big difference between a sievert you know all at once like from a nuclear explosion and a sievert given over a week or a month a little bit at a time one of the sievert all at once will will give you radiation sickness right away and and your cancer risk will come later and I should point out the reason we know this is in a very unusual case the reason we know this much about radiation doses at this scale is this is a common radiation dose for the population of Hiroshima survivors Karishma Nagasaki so that is a data source for understanding radiation illness it doesn't happen very often to statistically large populations the other population that gets this scale of a dose is if you if you have cancer one part of your body you're getting radiation therapy the radiation therapy is really intense on the cancer and they're trying to you're trying to kill the cells of the cancer itself and sometimes that bleeds out and a really serious solid bit course of radiotherapy may give you a sievert in the rest of your body so we have data from that also acute radiation sickness the kind of radiation that will just kill you is of order 5 sieverts five or more extraordinarily rare there's so many I mean there's only handfuls of events where this has happened other than it's a Hiroshima and Nagasaki obviously among chernobyl first responders great many of them just faced absolutely inhuman risks to put out the fires that share Nobel 30 dead 200 hospitalized do not in that group many many with people over - over 10 seabirds per hour carrying around pieces of reactor core in their hands on a roof no nope no protection of equipment the goiânia accident was a very very interesting case a big medical source speaks strontium 90 source I think got loose at a recycling plant and townspeople somehow got a hold of this pretty blue metal and we were playing with it and that led to four deaths 515 hospitalizations over five sieverts all cases were deaths so this is this is five sieverts is is run for your life so that's your that's your introduction to this actually it's an interesting case the people people with equivalent doses five Siebert's they were all dead the three to four severs case people who got it all at once died people who had it spread over a week in this case survived it makes a big difference so here's here's some units in the news new york times this was this is yesterday i haven't been following that i haven't had time to follow the news today this is probably all Darrent last offense at troubled reactors 50 japanese workers radiation close to the reactors was reported to reach 400 millisieverts per hour millisieverts per hour is a very common measure you'll see associated with a place if I tell you there was a millisievert per hour over there it means that if I go over there and stand there for an hour and then go away I've got 1 millisievert if I stood there for 2 hours I've got 2 millisieverts so we need to multiply by time so that's C so we know 5,000 millisieverts 5000 times the milli gives five that's five sieverts will kill you so 400 millisieverts per hour will kill you in 12 hours this this rate wasn't reportedly was not that high for 12 hours but you know there's there's a there's something you can understand about about that number after a blast inside reactor number two and a fire number four but has since drops back to as low as 0.6 millisieverts at the plant gate 0.6 millisieverts per hour let's compare that to texting while driving if you stood that paid for two months you'd get a sievert at that at that rate so I mean there's very different scales involved here you know death in half a day versus inconvenience and of cancer in over a month now here a world movie our news is reporting microsieverts but there's 8000 of them so Mike eight thousand micro sieverts is eight millisieverts per hour always per hour it should always be per hour if you're talking out a place but they get this wrong sometimes so here's the New York Times plotting as a function of time this early this week the radiation dose near the reactor at certain sites versus time so Monday there were little spikes of rate Tuesday are little spikes right Thursday they're a little Tuesday they're little spikes or big spikes of rate this this axis is supposedly saying 12:00 millisieverts per hour and then up here they say a measurement of 400 millisieverts was taken between two of the reactors no it wasn't a measurement of 400 millisieverts per hour was taken between the reactors people this is this is a very common thing to get wrong or maybe they're short handing it and not telling you elsewhere and this is so there I mean the reason the reason we go through this is so you have some intuition for what these numbers mean radiation at three locations in Tokai which is which is a ways away here's a spike to 0.005 millisieverts per hour so that is not a large number that's a small number people far from the site have not been irradiated yet not yet and they've been irradiated a little so there you can detect this and this is this is done in some kind of radiation detector so it's not it's not zero and one of the questions people always ask about radiation safety is well your tell your showing me all this data about Hiroshima survivors getting one Seibert is is the risk is the number of cancers you get from one person at once Ebert the same as you get from having ten people at a tenth of a sievert and 100 people at andhra they receive it I don't know probably this is this is a matter of some debate because there's just no data down here there is no direct knowledge from from epidemiology of a population that's all gotten 10 millisieverts in some way that you could follow them and see if they have a slightly tiny tiny increase in their kin what are already fairly rare cancers so nobody really knows what goes on down here the conservative assumption and I think there is some evidence for it but I'm not clear exactly how it works is that this line is just proportional so yeah tiny dose of radiation for a lot of people is the same as it gives the same number of cancers as a large dose for a few people up to some limit where the people are just dead and you don't they don't get cancer but other people propose this threshold model where anything you know below 100 millisieverts per year is just not noticeable and but nobody really knows the other thing people really know as I said when I when I show those cancer numbers I said number of additional diagnoses per year is that you know for the rest of the life of the person who's been irradiated or is it a spike that that gets better over time or is it or is it even this is it that your rate of increase of cancer risk has increased and so as you age you become more more acceptable nobody knows there's there's absolutely no reliable data on this I've seen hints at that the line goes up and back down but it's really not my specialty okay so that's that's what a radiation dose means if you get one why are you gonna get one or who's gonna get one and from what so here's the three populations of radioactivity what's going to get out this this chart is singularly uninformative on the question because what you care about is the chemistry here's our here's our periodic table we've got hydrogen helium and so on here's our actinides down here and here's the here's where induced radioactivity shows up stuff the reactor is made out of and some stuff in the air here's where fission products show up rubidium through indium ich iodine through gadolinium ich or the sort of two populations of fission products vary in exact picture here and the dye the actinides themselves our stuff sort of above and below uranium all the way down to where it becomes stable again which is led these are not technically actinides and they behave a little differently so how do you figure out what's gonna get out of the reactor when it when it goes off well let's look at the chemistry and here's the chemistry roughly speaking there's stuff in the middle the actinides most of the transition metals are there metals they behave like metals they don't dissolve in water particularly they don't they have high melting points and high boiling point so you can heat them up for a ways before they go into the atmosphere there are a couple of things which are worse over here we have gases carbon nitrogen oxygen and the noble gases argon xenon radon helium are are just gases at room temperature if you have a bunch of gas in a bottle you can just come off the top without without too much trouble there's a bunch of other stuff which is which is not actually gaseous but it's at least either sort of low boiling point or water soluble or anyway much more volatile than than the metals and that's that that's a particular worry so that gives you a guide to how stuff is going to come off of reactors the gases are gonna come off first the water soluble or sort of generally mobile stuff is going to come off next and this is it I think what you see pluriel that's this is technetium in the middle it's a little more water soluble than most things and the metals are hardest to hardest to liberate so they're they're sort of safest a very crude sketch of a generic reactor you've got a pile of fuel just all mixed together and it's mixed together with its decay products there's no way of separating them so you just have this puddle of all kinds of hot stuff you know you know can you you don't want that in contact with the water is he surrounded with is this zirconium alloy which is particularly good at withstanding radiation and being in contact with water and that thing is sitting there being hot if the reactor is healthy there's there are some activation products out here and that's your sort of routine radiation release from reactor but in the environment I mean there's really practically nothing outside of here so when there's a message I have no doubts when there's a meltdown what happens is this gets so hot you lose some of the coating so some of this protective szura callaway comes off or splits or or dissolves your burns somehow and so some of this fuel is has gotten out and liquefied at least lost his structure this is probably a picture so stuff that can get into the water is now in the water caesium iodine that's all that's all floating around in here stuff that can get into gas form which we probably also include some iodine is in the gas but if your containment vessel is still intact there's still nothing in the environment you have a hot tank and and you don't care about the details if you're a three-mile Island the next thing that happens is that the pressure in the tank is too high so you vent it you don't meant the bottom you don't this water to come out but you do it to vent the gas on top Three Mile Island was a nuclear accident involving a meltdown of the fuel we need a bunch wood puddled up in the reactor pressure rose in the containment vessel and the operators were forced to or decided to or actually don't know the details they somehow had to vent this headspace to get the pressure down so it's Three Mile Island all this stuff that was in the steam got into the environment so there's a big release of radioactive Krypton xenon some radon and that was it thereafter this was shut off this was cooled down somehow or other and we were left with a big tank full of radioactive stuff but not all that much radiation release by reactor centers what's going on it at the Fukushima site is that something else has breached in this containment and and we'll learn more about this I'm I am so far from an expert on this but roughly speaking this allows this gives you access to many more routes for stuff to get out of the fuel including things that that don't particularly volatilize like maybe technetium but that dissolve in water so whatever whatever water is escaping I don't know the details of this whatever water is escaping is allowing it has the potential to allow more radionuclides to get out and so that's step two these are still mostly these are still mostly fission products still a beta decay stuff where things get worse is when the fuel is on fire and there may be reports as of very recently today that some of the fuel is on fire it wasn't clear as of a few days ago fueled on fire means oxygens gotten in here hot fuel was exposed there's no water covering it up or cooling it down and metal metals do burn they are flammable they would rather be oxidized than the metallic and this this is bad because once you once you're oxidizing stuff well fission products in oxidize is act actinides can oxidize and they all forms smoke and the smoke is radioactive and that's your problem that's the serious problem and that's where a Three Mile Island like no detectable cancer is sort of event turns into turns into the crisis that's happening now this is very bad but still not as bad as Chernobyl how was Chernobyl worse well I wasn't Chernobyl worse there wasn't a containment vessel of any of any sort the lid just popped off when the pressure increased the cord was conveniently filled with graphite graphite is flammable it's like coal it's like a take so take a bunch of hot uranium ramp it up to 400 megawatts and then pour it on top of a mountain of anthracite coal and let it set on fire and that's what happened at Chernobyl so not only was it was there was Chernobyl burning like crazy but the reactor was feeding it was on it was a working power reactor producing visions right up to the last second and possibly afterwards I'm not I'm not entirely clear on that point by contrast Fukushima has been was turned off when the earthquake happened and it's been off for five days it is a warm reactor but it is not it is not an operating reactor in the case of Chernobyl this is a picture of the site from above this is this is just off Wikipedia which has a very good article on the topic as far as I can tell this is you see a little I've zoomed in here you see this little ring that's the lid of the reactor sitting there open and if you look down here you're looking into the bowels of of a live reactor this was all an explosion followed by an enormous fire this big plume of smoke that went up and the smoke was kit was what carried most of the radiation dose into the atmosphere which then starts falling down all over the neighborhood and putting putting this out required just absolutely incredible sacrifice so why is Fukushima is not that bad and why is it not that bad a couple of saving graces it's the reactors survived the earthquake intact there's a 9.0 magnitude earthquake and a bunch of reactors sitting right on top and nothing tipped over nothing cracked in half and except for this tsunami I think we're looking things were looking rather rather good they shut down property they inserted their control rods turned off their fusion turned off their fission reactions and then they survived a couple of before any of these breaches started and that's a that's a really remarkable thing these fission products remember you've been manufacturing fission you've manufacturing fission products as long as you've been generating power they're all radioactive so we're all eventually going to decay but a whole lot of them that came pretty fast so this is a graph of how much radioactive power there is as a function of time it's a log scale so here's an hour here's a day here's a week here's a month after you've turned off a reactor so the fact that Fukushima was off for at least an hour saved a factor of 5 on amount of harmful stuff in the fuel relative to Chernobyl survived for a day it's a factor of 20 another thing that what's worth noting is the thing that's catching on fire right now is not live fuel it's a 100 day old spent fuel station that's a hundred times less radioactive than been Chernobyl was in in fission products so that's a that's a that's that's a stroke of luck there root that it didn't have to work out that way another thing that's that's really a tremendous saving grace is the presence of an evacuation fairly prompt and not maybe not thorough enough we'll see but certainly a nearby evacuation by contrast at Chernobyl there is a city of 50,000 people what two three four kilometers away from the site they were they weren't evacuated until the next day in the 30 kilometer zone around Chernobyl there were another 30,000 people who weren't evacuated for two weeks all this radioactive smoke raining down in their heads it was it was it was really very very bad it was as bad as could be I found a quote in one of my books five days after the fire Russian officers coming up to a woman who is eventually going to be told to to evacuate she asks what's going on she says don't worry just keep on milking your cow she kept on milking your cow and the cows turned out to be the source of all the iodine that was going into the kids that gave in thyroid cancer so nuclides to watch what are you what are you watching out for in the news what's coming out of this reactor this is the so here's some of the moderately volatile stuff that certainly should be coming out now iodine-131 is what caused most of the cancers that renoble there's a lot of it released a lot of it got into people via this cow route the iodine falls on ground cows eat the grass iodine goes in the milk it drinks the milk and there were people via survivors actually who had doses of hundred sieverts to their thyroid remember five sieverts and the whole body is fatal 100 C roots in the thyroid gives you die red cancer pretty much right away but there are survivors with that sort of condition it's a short half-life it's not that you know you don't have to run away for too long and it'll go away on its own iodine rained out all over Eastern Europe and that was a rather quickly in those first eight days there was a about a half millisievert to just sort of everybody in Bulgaria lots of Eastern Europe had this cesium and strontium are really are sort of the worst of the crew they spread widely they're very they're very mobile the rest of Eastern Europe so add in the cesium dose and you get another millisievert over the next thirty years while this stuff is still right it is still around it's still detectable strontium similar there's less of it but it accumulates in bone in particular when you ingest it neither of them were all that mobile so they I don't think they migrated and groundwater too badly plutonium 241 comes out later there's a lot of it lots lots of it a little shorter half-life and for reasons I'll talk about it's easier to decontaminate when the fire starts as the fire may have already started is when when the well you remember these reactors aren't out to produce strontium they're not out to produce iodine they're out to run just as much vision as possible because they really want as much shortly of radioactivity as they can get you know you want to pump all of uranium down into this chain and get it stable as fast as possible so there's lots and lots of stuff in that collection with very short half-lives if you have a lot of stuff with a short half-life it means it has to get rid of itself really fast which means it goes to K - K - K - K very fast decays means lots of radioactivity per unit stuff so here just this is just some of the things most abundant in in Chernobyl suit some of it very short live three days but that's I'm tremendously tremendously radioactive 30 days 60 days and you have to leave town for a while before a 60 day element will have decayed you know multiple times where this is such that it's really all gone nice thing about the suit is it doesn't go as far as the volatile the Krypton goes all around the rift doesn't last that long the strontium seems to go further for reasons that aren't entirely clear to me the suit can can get rained out so it settle down near the reactor it settled on the heads of the first responders they were just their clothes their their bodies their hair were just covered in this kind of stuff and this is this is why you're so concerned about the fire at Fukushima not necessary afraid the plume is going to get the Tokyo although you should be afraid of it you should worry about it because you can't send firemen into a cloud of smoke containing containing this pile of radioactivity yeah half-life so radiation is a stochastic process it's an even worse description isn't it it happens if you have a pile of a thousand atoms you have a pile of 90 of a thousand Serco Neum atoms and you wait 60 days what you have now is a pile of 500 zirconium atoms the other half of decayed already you wait another 60 days well there you hand that to somebody else and say say AHA I have a pile of 500 Konya madam's they wait 60 days and they have 250 they hand that off somebody else's they say oh I've got 250 sodium atoms so a half-life is the time for half of it to go away that is an absolutely perfect curve all the way out we even there's no deviation from that half so don't expect there to be Oh after five half-life's it's really all gone no after five half-lives two to the fifth of it is gone all but one 30 seconds is is that so this gives you something with with a 60-day half-life you're going to want to wait for 60 days times 5 6 10 8 before you before you want to come back and have fun so when we're talking about smoke that's why that's what these stay indoors advisories are all about and that's why they should be taken seriously I who was I forget who the the us element security guy was he told you to put duct tape on your doors if there was ever a bioterrorism incident nobody took that too seriously when when the Japanese authorities say stay indoors because the radiation this is what they mean if there is soot falling on the driveway it's it's decaying and it's giving a huge radius and ocean to your driveway and that doesn't bother you it does behave like soot it doesn't behave like a gas so it mostly falls down so if you're staying indoors it's not falling on you and it's not giving you a dose so I mean there there are defenses against this kind of stuff they aren't accessible to the first responders but they're accessible to people in the cities the other nice thing about soot is it's compared to strontium compared to cesium it's easy to clean you can you can it's it takes time but you can clean it up you can wash it off of surfaces you can brush it into a can and you can restore a suit contaminated city to a livable state with respect to this so it through to it to a certain extent agriculture fisheries I mean Chernobyl spent a lot of a lot of effort cleaning up trying to clean up a lot of agricultural areas food prime farmland a lot of what they had to do is just dig up the topsoil put it in the truck and get rid of it sometimes you can turn it over just kind of hi there radioactivity a little deeper which you know and you don't it's not you're hiding it forever you want to hide it for want to hide it for a couple of years it takes for it not to be a problem anymore the other thing to remember about this this kind of table is unlike chemical hazards you don't care about each of these elements separately you know if I tell you that you need to avoid you know mercury and you need to avoid PCBs and you need to avoid I don't know what else plastic bottles because they have this arsenic derivative in them you have to avoid each of those things and there's a whole by the whole list of separate little chemicals that you would worry about you need to worry about each of them radioactivity you don't need to worry about each separate little thing you need to worry about your dose total dose so you add it all up it doesn't matter where it came from you might worry about your dose to your thyroid and your dose to your bones your dose to your skin might they might be a little different but for the most part your just need to add these things up so I this is that's all I had prepared I wanted to say that a funny thing that happened in the wake of Chernobyl was at least by the standards of the Soviet Union a lot of decent epidemiological work was done on people who are exposed to this radiation that's how we know about the the large number of thyroid cancers if if people believe these numbers but the 10,000 maybe 20,000 thyroid cancers caused by a house fire and one of the funny things that that epidemiological survey found was very few cancers but absolutely terrible health outcomes they found a lot the depression they found lots of PTSD they found lots of stress lots of fear because nobody told them anything they were told your town is has been hit by a reactor and we were trucking you all to Kiev leave everything behind and go and then get a handshake and see you later they were not explained and nobody explained to them what a seabird was nobody nobody you know explained to them that they can get rid of the lead by washing their hair they were just baffled and so they spend the rest of lives thinking that the reactor is slowly killing them whether or not it is this was a huge educational communication failure and absolutely unnecessary is an absolutely avoidable tragedy and and that's science that's part of the reason I'm here you all have the information your friends and acquaintances in Japan should have the information you don't need to listen to authorities to tell you whether you should worry about whatever dose you have say count the millisieverts count them yourself there will be in the paper you can get a Geiger counter you can measure them and you decide what your risk tolerance is you decide how to respond that's something that the people that you're Noble or not we're not and a chance to think about my feeling is that the worst case radiation hazards from from Fukushima are local are there they're bad very bad very locally somewhat bad in a somewhat broader region but but still confined to part of Japan and for the most part they were mitigate Abul the cities that get hit by this badly will be cleaned up Tokyo is not going to be abandoned and the worst part the best parts of that mitigation have already happened and the the early evacuation is by God the the best thing that could be done you don't have to worry about soot falling on empty houses no matter how much of it there is Chernobyl didn't have that luxury people were already there when the smoke started falling the next thing that we will need is watch out for if iodine-131 levels go up Chernobyl that all came in through food I mean don't don't take an iodine tablet and keep drinking the milk just stop turning in the damn milk but that needs to be that needs that needs to come from the government that needs to be somebody credible putting restrictions on things and making sure you know unscrupulous farmers aren't selling meat on the black market or something in this my feeling is also that the global radiation hazard is is nil this is these are large numbers of radiation but the earth is a large place and there's lots of radiation here already there's no evidence that this tiny this large amount of radiation when it's spread over the world as they say the Krypton radon dose will has any health hazards that are that are measurable and in any way at all so my my feeling is this is really really zero California does not have to worry Korea does not treat China there's not to worry even Tokyo so we'll talk about Tokyo is not so far from Fukushima a plume in the wrong direction really bad luck on the weather so you know you watch the news then go indoors if you're told to if you're if you believe in the linear dose-response relationship you should say hey wait how can a small dose given to a billion people is the same as a huge dose given to a million people so how can you say that it's not a problem I'd say if you're if you're really worried about extremely low-level radiation call very very low level cancer the best way to stop that is to stop burning coal not to not to stress out about exactly what's happening here moreover you know we all have a limited amount of kind of psychic energy for worrying about things it's a stressful it's a stressful thing it takes energy takes energy for us takes energy for our friends in Japan and you I think you my message anyway this is just a not obviously not a departmental statement this is my personal statement you should save your energy for the people affected by by the tsunami and for the the real radiation hazard which is the 50 maybe now 100 plant workers who are still at Fukushima putting out the fires thank you everybody thank you for coming so 1 1 before we start the QA Theo Theophilus would like to give a quick update on the status of the reactor you can take the microphone and here's that pointer in any case useful to have up there the pointer is this one yes do you have up there the geometry of concern here this reactor and most of the time of course we want to spend to answer your questions but the latest is the following the initial problem was with the containment which is this part here what you see here is the reactor vessel and this is surrounded by that shell and that communicates with this torus it's like a doughnut that is all around so this is what you call primary containment so if this is integral any radioactivity that is here it's just like what Ben was showing the little can contains everything now at the beginning of course our problem the poems arose because there was no power to cool these reactors so the fuel became exposed and the fuel start overheating and then this economy that was their stocks advising and the hydrogen came out in this in this area here and then he came out in this area here through those bands that you see here and it looks to me now like they haven't talked about it yet but it looks to me that this chamber here was slightly damaged from the earthquake so when hydrogen start coming out of here then we had an explosion in this in this room and this caused a subsequent failure of this container this is not good news because now we lost our primary containment still I remind everybody that in order for the activity to come from here to the outside it has to go through the water that is in there and that water has a retention property it has a property of keeping a lot of the activity inside however this property is lost very quickly when this water gets overheated and gets near boiling still there has some retention probability but it is not as good as if the water was cold now suddenly as of yesterday or maybe a day and a half ago however my concerns and the people that are involved in this sort of following it shifted radically from the reactor to this area here which is the spent fuel pool this has become a major problem because it looks like in the fourth reactor do you remember there are six reactors there there are three reactors which were suffering because they were operating so those are the reactors that were shut down and now we had to do with the decay heat as you just hear and the other three reactors were essentially without any fuel in them all of a sudden now we hear that in the fourth reactor we had an explosion the top of the fuel bowl now why this is a concern the concern is that there is a huge amount of fuel that is held in here typically from anywhere from four to six cores so its equivalent like a six reactors at the most fully radioactive contained in those pools and so that's the fourth reactor which had shown up to this point no indication of difficulty now we have fire on the top of the pool and we have an explosion which destroys the roof of the this building here which is called the secondary containment so to me that's a very big concern because this pool here once it is lost the water and lost cooling ability the zirconium the cladding oxidizes and that becomes Auto catalytic actually near the end when still some water vaporizing that adds to the fire so to speak and is almost like cut cease fire done that creates a big spike on the release of radioactivity alright so now what the situation is the following reactors 1 & 3 have lost those pools and the fuel is basically destroyed in their reactor number 4 the same situation reactor setting already down here reactors 5 & 6 which again they are not operating reactors there right now these pools are overheating the good news is that the rod opened so now they have access by the rod so they can bring fire tracks and also they just hear the like half an hour ago just before we came here they got electricity they have electric power now so those are very positive very positive news the question now is going to be and this morning actually was trying to puzzle how do we cool those pools up here and I sort of had been advising through some channels that I they consult with me for the government I've been advising that to be ready if necessary to controllably collapse this whole pool into the floor because as long as the sitting up there there's no way to cover it and if you cannot earlier on about the day oh I heard I said why don't you get helicopters to dump water on the top well they wouldn't let helicopters fly it because it was the level of radiation was too high so that was no again there so if that doesn't happen the only other way to do is to bring the fuel down and again remember the main thing is to cover things with water as deeply as we can and there is a lot of water there now they have access with the fire engines and they can do that and in that case what would that require would be to basically controllably with explosives to cut out through his floors the floors cut through and then cut this pool come down another concern that we have and it is not clear yet is that the because there is plutonium also in this some of those are mixed oxide some of those some of this fuel because this plutonium it is a possibility if it is getting into certain configurations to become very critical so it can be critical if it's critical then you can just go off with again going to fission and that's that's a very bad thing we want to make sure we are avoiding that so the just very shortly the message is that I feel pretty reasonable about this area here right now my major acute concern is about this and about all the six reactors and hopefully nothing will happen to interrupt they brought fire hoses that he have cannons that they can shoot water 200 meters but the problem is that they have so much debris on the top this water cannot get into the into the pool so now they have to I hear that they are trying to send people up there to clear out the debris so it's very very difficult problem and finally one last thing to mention is that according to analysis were done in this country again we there was hardly any cooperation because they basically did not give us information and they sort of held like that only now finally they said yeah we warned out to cooperate and and this now just beginning this process but already the NRC here the Nuclear Regulatory Commission took the position that it was a mistake to evacuate only 30 kilometers based on analysis that are done in this country relative to dispersal of radioactivity they say a minimum of like 80 kilometers should have been the radius of evacuation my concern is that if this problem becomes exaggerated and if the weather shifts right now the winds are going east which is very nice if the weather sits I think we could have real problems now leave it at that let's leave this up here just in case questions we can point to things here sorry Patrick yeah so we have myself Theo and Patrick and Cray from the Department of History are happy to answer questions and I think since this is being recorded it'll all be on the web sometime tomorrow slides and audio and if we pass you the microphone then your questions will also be on the web which I think will be useful so yeah there's microphone over here if you get that every how come they are not using robots since they cannot take send people there it could be robots doing the work of the fire fighting well remember now this is all dark in the house this is the the help that is needed up here the roof has collapsed in some of those reactors how are you gonna use the robots the difficulty is in getting water up there and in order to get water up there either you have to connect lines and again this has been obviously that's why the system failed because normally these books are being cooled the reason that they are losing water is because the heat cannot be removed and gradually they come up in temperature they begin to boil so the robots is not an option here even to remove the debris to open up so the water could go so at Chernobyl the people who were assigned to clearing the brief in the roof were referred to as bio robots could you extrapolate any of these conclusions to San Onofre or Diablo Canyon a both of which are in seismically active areas which conclusions we say extrapolate conclusions you mean what we didn't run conclusions here except to tell you that there is some problems that still need solved for this case here so maybe you can rephrase your question San Onofre I think is a pressurized water reactor yeah here the question exactly what very significant earthquake in Southern California how much radiation would be released San Onofre is and a happily urbanized area Diablo Canyon not so but they happen to be both relatively close to Santa Barbara so I'm just curious how he might be affected by radiation I think I can I can try this and you go nuclear reactor such as any of those reactors light water reactors needs to be cooled after it's shut down there is always a possibility of an extreme earthquake that will disable systems just like happen here that will not be possible to keep cooling the reactor if that becomes impossible then there will be meltdown the meltdown will penetrate eventually the containment so in those because of the design of those reactors you are not going to have the same intensity as you hear for example from this suppression pools I mean the spent fuel pools the containment design is also very different is it dry containment you call it it's more robust it can take much more pressure it's more controllable you can vent it to the outside if you have hydrogen for example you had doesn't work outside and will explode outside if he needs to explode so I will say that one can envision situations where also pressurized what the reactors can show a very adverse response because what comes along with the earthquake is not only the damage to some components the control system is lost power is lost infrastructure is lost the problem here was the infrastructure or the loss to the point where people couldn't get there with tracks only just now gained access so every law probably I would I like to say is every low probability event is sort of totally unexpected and don't think of something happening in San Onofre or double canyon there'll be anything like this the question more like is what would be the other next low probability event that we want to we must protect against and that is a much more general question and what I call the defense in that one should have we have prevention we have mitigation we have emergency response and I've been advocating for quite a long time that you should have basically a rock bottom defense for all those reactors like everyt everything else fails there is an ultimate battery defense one thing III II did study here actually feel exactly this design for the u.s. 25 years ago exactly for these kinds of things and we said that if you have a meltdown you feel you fill up this area this this container you fill it up with water and if you did that you're going to prevent an immediate failure of this container if you didn't fill it the melt will grow there will penetrate through them through the boundary of the shell and then you've got to release to the outside and this became part of the procedures actually they have the same procedures however if you don't have a billet to put the water there so when you have a major event many other things break along the way and that is why we want in this country for passive reactors who are actually virtually you can walk away so we have now both pressurized water reactors and boiling water reactors are completely passive but again it is not to say that even these passive plants they will be not be a challenge that will fail them I've heard that Hiroshima may well underestimate cancers because the living conditions were such that only a really robust subset of the people survived to get cancer in the first place I'm not an expert on the topic at all I'm sorry I can't comment I guess I have two questions why don't we hear a lot of reports about the color of the smoke coming out of the reactor sort of how can we decipher that information sort of intelligently that's how do you what yeah and secondly with the salt water being poured on to the containment what sort of risk you see with that directly contaminating sort of sea sea life and if you could maybe expound on what contaminants may enter the water and sort of the causal procedure there and rest well right now our problem is to get the water in there and there is not much water leaving the place it would be a long time before any water actually lives the place ultimately we have to be concerned about what happens to all this water we have to be concerned whether the the melt because I expect that the melt is going to penetrate this vessel maybe already did some of it we don't know yet but eventually I think is going to penetrate because already in two of those reactors the core geometry has been lost completely and then when that happens there is no way to kill cool the fuel the fuel just keeps going down okay and eventually we have to come out here again another issue we have with our present reactors again I raised that 10 years ago 15 years ago but it's too much of a difficult thing I guess for the industry and the regulators to deal with we still don't know for our reactors and still remains a problem for me is that if you have a meltdown whether you can put all the water here you want weather that will keep the fuel from keep going down into the concrete we still don't know that and I had suggested to actually put in some systems that will actually stop from doing that but it's a pretty serious thing oh the necks exactly what happens normally just the main what little was left there even most of it went up whatever little was left he kept going down on the other hand at Three Mile Island the the quartic or puddled and it stayed in there it stayed in a containment vessel the Mile Island he came within a manometer from going through because it just was like II push the button and started the pumps and stopped it about 20% of the melt only actually came down to the lower head and was cool there I think in this case this is not happening another thing I should mention that again we mentioned this concern but of course there's no options at this point but when you put in a boiling system you put salt water and you keep boiling what happens your cumulate salt eventually that salt is going to fill up already based on the estimations that we have how long they've been feeding and how much they've been boiling there's a lot of salt in those cores and we don't know how much of it is plugged up that is going to interfere with the cooling also yes I have a question so just an update there's some videos online an hour ago of helicopters dropping water on the on the pool such as the the latest I saw one hour ago there were military helicopters dropping water and so my question is the power the power stations when they're operating there nominally around 500 megawatts each and you mentioned there were around six cores stored in the spent fuel ponds you know what yeah there are six of those right so when when the fission reaction stops the power goes down from 450 megawatts my question is what is the power of the spent fuel that's in the ponds right now what power of so how much water do we need to dump on those things to keep them from then the power is very low nevertheless it is of the order of magnitude that if you leave it for like a day and a half it will dry out that's really what happened in reaction before they in the reactor number three I believe they have known number four they have a core that is only four weeks old that's the newest core that they have at four weeks old you get about 0.1% or yeah it's right there we were asked to make that about 0.1% of the decay power so if it is one tenth of a percent so five four hundred megabytes if if four hundred it would be like point four megawatts when some reactors has 700 so be point seven megabytes still is not negligible for a several hundred kilowatts a lot of power Thanks and again that's only from one I'm sorry this is only from one of the core so you have to multiply time six to get the total demand for the pool for for heat removal so to stop the fashion from reoccurring with the spent fuel couldn't you grind up boron and just mix it in with a fuel to capture the neutrons our problem is not with the fission power already the fission is shut down in fact we shut down and all the reactors right after the earthquake so there's no fission is just the all the decay power that we heard earlier in the band stock that that this is going to keep producing has nothing to do with you mentioned that the phases may occur if you don't keep the fuel separate thing if the stuff came down and get into an unfavorable geometrical configuration because of the presence of plutonium then you can get the critical and well I mean how do you when I go in there you have to if you have water we have to put it inside of that hot infernal not so easy but maybe maybe that's not such a big problem because I just hear that that in reactor number four they think that the fuel in the pool already collapsed and nothing happened it looks like it's already melted the question is when that's going to go through now the bottom because it will go through the bottom eventually is it not possible to design protective suits that will allow people to go in without damage to stop so for alpha radiation the got our three types of radiation for the alpha particles themselves a bunny suit is fine this cloth will stop them betas and gammas to this to stop one to stop half of the gammas you need about three centimeters of lead so so no it's not it's not really it's not really feasible at all even in nuclear in real nuclear cleanup scenarios it's very difficult even to build robotics because electronics don't survive the I was watching videos recently if the robots being used to clean up radioactive waste sites at the Hanford Lab they have to build all hydraulic robots because they cannot put can cannot put electronics into these high radiation environments that would have been that probably would have been true and I Rufus are noble and I suspect it's true in some of these environments also I think the historian would like to say a few words so Ben didn't invite me here just to be a moral support he actually asked me to say something bridging on intelligent I tend to think about this I guess through a different lens and that's not thinking about it in the sense of 2011 but thinking about it more from maybe the framework of 1954 and the reason I picked that is threefold in 1954 that's when Japan's nuclear power program actually started and eight years after the start of that program they had a working reactor that was initially started with help from the British which in some ways both directed and directly leads us to today but in other way and I think it's what's important is that Japan's nuclear history is very different from our own we don't think of World War two as a nuclear war but that's how it ended and Japan's experience with that was very different obviously than ours but in 1954 also there was a time when there were lots of nuclear tests being done around the world and there was one specifically in the South Pacific a test called Bravo that resulted in explosive power about two and a half times greater than what the physicists and engineers in the United States working on the project thought what happened as a result of that a Japanese fishing boat was contaminated with radioactive fallout it went back to Japan one of the crew members died and it sparked a panic in Japan because obviously the Japanese depended heavily upon fishing stocks and there were concerns about that but the third touch point coming back also to 1954 is that's also in the movie Godzilla was released and the fact you're laughing makes my point for me which was in the United States this was seen as sort of a cartoonish film of a guy in a rubber suit walking around smashing buildings models in Tokyo but in Japan the movie was seen very differently it was seen as a drama a serious exploration of Japan's relationship both with the nuclear age but also a way of exploring how this society that was transitioning after World War 2 was going to come to grips with modern science so those are just three different perspectives I guess I could offer Thank You Patrick so maybe we have time for approximately one more question and then we'll let you go I'm proud to have the last questions I'm an architect in a planner and I'd like to know the panel's feeling of reactors as the supplier of energy for our communities in the future let's go from 1954 now to 2050 or 2040 and let's talk about the spent rods in terrorism and the idea of the continuous rods where they go and what are we doing to our environment and it's a reactor the idea of the perfect power supplier in the future maybe I think maybe I can say that after that first it would be nice if we could design a reactor that didn't have radioactive waste that came out that that would be the perfect power supplier for the future there are technologies that get remarkably close not that not nothing that exists now but there's discussion of something called accelerator transmutation of waste which is expensive but you can completely destroy you can take any fuel any mixture put it into this thing and it burns it back to the line stability at a at a cost of I think you you you reuse 10% of your power in the sort of recirculate er and you can just draw out all your fuel with no with no proliferation hazard because it doesn't make plutonium there are addition there are new reactor cycles that are designed not to make plutonium and so we there are avenues towards solving the proliferation problem the thing we do not have is an avenue for producing non fossil fuel electricity which in every possible measure in in damage to the environment and damage to human health in even in you know in millisieverts the impact of coal-based electricity on our environment is absolutely horrific and and that's that's the right way to make the comparison it's not just is is nuclear bad but yes there are bad things about it but is it is it worse than the alternatives given the alternative at the moment is coal yes it's its nuclear I think is much much better than alternatives waste disposal is something I take take some interest in it's it's an evolving problem and there aren't there are not great answers yet except for for going to new except for going to new fuel cycles but I think those cycles are on horizon you know as we started building reactors again so we could actually implement one of them okay I just like to add a couple of things to that first of all I think is a major mistake and is a measure in congruence to have nuclear power and not have the ability to reprocess that all that creates is a huge amount of fuel that is lying around in pools and the keeps are adding and adding and adding and nobody wants to dispose of it so we are creating a huge problem by this first secondly about the future of nuclear power I want to say that the whole thing needs to be rethought the infrastructure basically was destroyed in this country in the last 20 or 30 years because of the way that nuclear power was handled politically and the way that are the other forces played into that personally I left actually the field of practicing nuclear safety about 10 years ago unilaterally I left because I just became sick of the way that things were being done I think we have major problems in our institutions and that means regulatory institutions governmental policymaking institutions on the other hand the industrial institutions and they all need to come to the new reckoning of how they are going to behave how they're going to organize and how they're going to go forward in a real secure way that makes sense so you don't have things like this happening in this country or in other place as well and that creates a you know a lot of there are a lot of competing forces because these economics you you try to ask to protect for earthquake 9 it's going to cost you not the same you protect for earthquake seven and now then already ten years ago nuclear was not competitive so now you are asking how you're going to do that so it's the same thing like you're killing it so but I think personally I believe that the whole thing needs to be rethought and I have great doubts whether as a country given how the whole political situation is were able to do that even so it's not good story and that about I think that not a good story pretty much sums up the

Channel: Kavli Institute for Theoretical Physics

Views: 60,077

Rating: 4.0291262 out of 5

Keywords: kitp, ucsb, kavli institute for theoretical physics, physics lecture, physics, fukushima, three mile island, chernobyl, nuclear

Id: rMRon8aPxmk

Length: 81min 49sec (4909 seconds)

Published: Sat Dec 30 2017

Reddit Comments

[u/HazMatsMan]

For laypersons it’s easier just to consider 1 Roentgen = 1 REM = 1 RAD = 1 cGy. To go to SI, 1 Roentgen = .01 Sv or Gy or 10 mSv. 100 REM = 1 Sv or 1 Sv = 1 Gy etc. Most people here will be thinking about gamma radiation and tissue so the RBE is 1 and you can round the .0096 to .01 or 96 to 100, etc.

[u/Foxstarry]

For our purposes 1 Sievert = 107.185 roentgen roughly and 1 roentgen = 0.0087 Gray in air and 0.0096 in soft tissue. Sievert is the preferred method for current understanding of damage as Gray doesn’t take into account types of radiation.

Source https://www.remm.nlm.gov/radmeasurement.htm

[u/joey_bosas_ankles]

Maybe you want to phrase it "Nuclear chemistry/physics fans," instead of "Radiation fans" sounds like people that want to visit and hug the Elephants foot.