An Earthquake and a Tsunami Hit Fukushima

you on March 11th 2011 the worst earthquake and tsunami to ever hit Japan took place this was no ordinary earthquake Japan is used to earthquakes they build for earthquakes but they don't expect a magnitude 9.0 fourth largest earthquake in recorded history only a few years ago March 11th 2011 the thing was that this earthquake was offshore so not only did it make a lot of shaking but it made a tsunami a tidal wave water 40 meters high 40 meters giant wave this was a disaster the Great Eastern Japan earthquake in tidal wave huge natural disaster the epicenter is right here city of Sendai is here the tidal wave the earthquake this actually killed over 18,000 people destroyed billions of dollars of property homes businesses shipyards factories enormous amount of damage a huge humanitarian and economic tragedy there also happened to be a nuclear power plant four of them right here on the coast in a town called Fukushima now like many of the other factories and many of the homes businesses buildings of course the buildings on the nuclear power plant were affected the number of people that were killed because of the nuclear power plant zero of some of the workers at the plant the people heroically trying to clean it up trying to prevent the accident from becoming worse received radiation doses not enough to make anyone have radiation sickness but some chance that they may have an increased risk for cancer for those maybe dozen to a hundred people that were affected by working on the plant at the time 18,000 terrible tragic loss of life generally the safety systems at the reactor worked no one was hurt now let's examine this a little further this is the type of devastation that took place that that thing in the middle there's the ship a 40 meter high wall of water and a magnitude 9.0 earthquake is an enormous disaster here's another picture giant ships tossed onto land buildings roads infrastructure totally destroyed and so with that type of destruction of infrastructure how did the nuclear power plant survive here is a diagram of the four reactors at the Fukushima complex one were 1 2 3 & 4 you see numbered there there are right near the ocean's edge because like any power plant you're going to generate steam in a closed-loop system which will turn a turbine and spin a generator you need to cool off that water on its way back condense it and that you can use ocean water for it maybe warms up very slightly so power plants are typically built by a body of water and this was no exception these reactors were built in the 1970s already had 40 years of operation probably near the end of the lifetime of the plant anyway so economically it was an economic success they were well paid for so to understand what happens when this I am 40 meter wall of water washes over a nuclear power plant let's examine the power plant itself here is a cutaway view when I several important objects to notice first is where the ground level is out here this is a elevated structure the second is this red object in the middle that's the reactor Pressure Vessel and right about here at the bottom and the pressure vessel that's the reactor core that's where the nuclear material is now like all other Western reactors and unlike Chernobyl there is actually a containment building something that in the worst case will hold the radioactive material that's in the reactor fuel itself the spent reactor fuel that will hold it inside and here let me draw for you the containment building it's this three-foot thick concrete structure enclosing the reactor an extremely impressive thick strong even earthquake proof material containment buildings didn't crack didn't fall apart all right just to give you an idea scale as a person right here these are pretty big buildings in a big reactor core so one of the things that compounded the problem at Fukushima was that one of the units was being refueled at the time I want to draw your attention to this area right here this little box represents spent fuel you see the crane that's up here if you want to take the fuel out of the reactor core what you do is you take off the top the containment but you shut down the reactor first take out the core take off the top open up the top of the reactor vessel move your crane over lower the cables down pull the fuel out bring it over to here and down in this enclosure this enclosure is filled with water which is wonderful shielding and it keeps the spent fuel from getting too warm notice a couple small problems first this is way up in the air round levels down here and secondly this is not inside the containment building now it is inside the regular building but you might notice that the concrete roof of the building ends here this is open so you can drop the the conveniently drop the reactor fuel rods down into it and the top here is thin pieces of sheet metal they actually intentionally call them blast panels and they're called blast panels because if there's a hydrogen explosion they're supposed to blow away if hydrogen gas somehow and so accident gets a evolve from the spent fuel it'll accumulate up here in the top doesn't take much to blow up hydrogen blows up hydrogen the bass panels will fall away no damage to the containment vessel to the reactor core etc but we can have the top of the building just blow off its panels so that that explosion will get only effect things that were designed to be able to blown away in the first place so so what happens to the whole entire infrastructure in the world right well we have our our tsunami demonstration all right very nice there's the coast of Japan there's houses I see we have Dora we've got a nice little puppy right and and then we have a tidal wave an earthquake all right tidal wave earthquake shake there we go this plane turn away all right all right the only one that was happy is the Frog sorry Dora so the earthquake happens and the reactor scrams safety control rod activation mechanism the control rods go into the reactor core they absorb the neutrons the chain reaction stops no more chain reaction the three thousand million watts of power is now no longer but remember that the radioactive substances in the reactor core are still dividing that's why they're radioactive that's what it means they divide when they divide they give off heat the heat is not at a hundred percent you can see that the heat drops to about six percent that's in a second doesn't take us long a minute or so later or ten minutes we're in this range now of around two percent of the power these are two different models for two different types of reactors but you can see it's gonna be pretty close we're basically at two percent of the power two percent is still 60 million watts that's a lot of heat so what we need at this point is we need to make sure that the fuel is cooled let's go back to our picture here so up here we have these stored fuel rods because they're refueling the reactor so spent fuel is here it's been there more than 10 minutes it's not at 60 million watts it's been there maybe days hours some matter of time but it's still making 10 million watts still hot and this is why this thing needs to be filled with water you've got to keep water on the spent fuel when you have the earthquake the containment building is fine press this bill and get some cracks in it right and the water starts draining out not a problem because reactors have backup systems that pumps we impart more water in fact we do have to worry about the core becoming unneeded too we have to keep water in the core as well containment building might be intact but remember that water comes out into this larger structure because it's running turbines and the like there's still some ingress and egress into the containment building and you need to keep water on the core power plants are designed to have backup systems backup electrical generators electrical generator indeed comes on because the power plant has scram there's no longer making electricity but the backup diesel generators start yeah kind of start because after all remember what started this it's the earthquake and not very long after the earthquake comes the 40 meter high water the reactors are up on a bit of the hill and it even had a seawall built around the diesel generators in the diesel storage for them because after all what if there was a tidal wave we want to make it safe from that they didn't have the wall quite high enough I think I read it might be any of thirtysomething football and they had 40 feet of water hitting it so water washes over the electric generators that's not a good thing all right let's find out what happened and what happened to their electric generators they stopped working I think oh sure looks like it okay it's not working all right so the diesel backup generators fail because of the tsunami the water has rushed over them they're not making electricity don't worry power plant has a third backup system for its electricity it's got batteries and these batteries will last a long time six hours you might think six hours sounds great because hey you know you had a problem your generators failed just have to have a new generator brought to the power plant to run the emergency backup pumps or maybe you bring in more batteries maybe in the six hours you fix the generator that went down all sorts of things you could do while you have this nice backup window except of course if the nearby 18,000 people are now dead that the water has washed over and destroyed all of the buildings the infrastructures the roads the communication systems the cell phone towers and everything else six hours isn't long enough the batteries run out now you have the problem how do we keep water on the spent fuel how do we keep water on the core with no electricity we don't the fuel gets uncovered when the fuel gets uncovered it starts getting warm when it first starts getting warm the bit of water vapor that's still around can decompose into hydrogen and oxygen hydrogen goes up of course it's trapped in this area surrounded by the blast panels and doesn't take much you have a hydrogen explosion so the blast panels do their job and they blow off for an after shot regular concrete structure in the containment building are all still intact but of course the news media says Fukushima reactors blow up the tops blew off of three of the reactors in the blast panels number three where the spent fuel was was a little bit more of a complete blow off because you had more hydrogen evolving from the exposed spent fuel we look at a timeline of the events this is looked at in terms of radiation dose now we've had some segments in this MOOC already that describe radiation effects the levels here are in millisieverts per hour and so 10 millisieverts per hour is a REM per hour that's a pretty high dose you can see here at the beginning the doses were very low but then you have some more significant events facts someone you intentionally have to do because you need to open up the containment building and let some of this radioactive gases that have accumulated out Japan is an advanced place and this was 2011 everyone's wearing radiation monitors radiation monitoring is done throughout the plant but we do have an emergency going on and some plant workers knowingly we're exposed because they could keep working and be able to we do things to keep the reactor from overheating even more these red measurements here were represented at the main gate there are some small periods of high levels of dose right of course this goes on and in time they have the reactor finally under control a lot of things have to happen in the meantime very clever use of sea water and emergency like fire pumps pump the water off a the roofs off the building aim the water into the spent fuel ponds do just about anything to try to keep water on the core so that the convection can cool off the hot fuel we go to a expanded view we can put some of these radiation doses in perspective here is a great chart and it shows you again in millisieverts per hour this level right here is riding on a high altitude or a jet plane right these are the kinds of doses that you get all the time you live in a radioactive environment you're radioactive itself now up in here we have things that are not going to give you radiation poisoning right they may increase your risk for cancer if you sustained that type of level and up here we have really terrible disasters like the things have an atomic bomb or Chernobyl this graph here shows you how far away you are of the different events this was the Chernobyl core these are many orders of magnitude factors of 10 this was the quartz Fukushima at the worst part this is no one's exposed to this level mind you right because they're not actually in the core so inside the containment building right and as you go further and further away you can see that the highest radiation doses towns at their highest points we're at a level like this this is nothing at all like the levels that were experienced near Chernobyl and soon after these levels top drop down Tokio here is in the van that God at most the type of radiation doses you might get from some other everyday activities now let's look at an expanded view of time again these are those same spikes you saw in radiation on the last graph finally of course they're putting this under control variety of things happen over the next few days which are going along here and we finally get down to even now in the current time at this continued slope that the cores themselves are still highly radioactive and need to be cleaned up but clearly the stuff is contained you [Music]

Channel: Illinois EnergyProf

Views: 196,942

Rating: 4.8738065 out of 5

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Id: lOqFr87Xh-g

Length: 20min 35sec (1235 seconds)

Published: Tue May 14 2019

Reddit Comments

[u/Last_Aeon]

Fukushima just shows that weCAN control accidents.

Chernobyl is just a series of code violations by stupid dumbasses