Speaker 1: Welcome to brain Stuff from house stuff works dot com,
Speaker 1: where smart happens. Hi am ourshall brain with today's question,
Speaker 1: what the heck happened with Japan's nuclear power plants this weekend?
Speaker 1: As you'll recall, Japan had its giant earthquake and tsunami
Speaker 1: last Friday, and right after the earthquake, everything looked pretty
Speaker 1: much fine as far as the nuclear power plants were concerned.
Speaker 1: The New York Times ran a story about how everything
Speaker 1: looked good. There were no major problems. The reactor hadn't
Speaker 1: cracked or you know, fallen over anything because of the earthquake,
Speaker 1: and it looked really good. But then by Saturday, things
Speaker 1: had taken a turn for the worst, so there were
Speaker 1: reactor buildings exploding. There was all kinds of talk about
Speaker 1: meltdowns and China syndrome and all this other stuff. So
Speaker 1: when you think about it, a nuclear power plant is
Speaker 1: supposed us to be one of the most amazingly engineered,
Speaker 1: super wonderful things in the world. With umpteen levels of redundancy,
Speaker 1: and every single contingency thought about and poured over and
Speaker 1: inspected both nationally and internationally, there should have been nothing
Speaker 1: that could go wrong in Japan's nuclear power plants, and
Speaker 1: yet it did. So what happened and how did things
Speaker 1: go from being really quite stable to completely unstable and
Speaker 1: leading to some of the worst nuclear accidents ever to
Speaker 1: occur on the planet. So let's take a look at
Speaker 1: what happened step by step, because it really is an
Speaker 1: interesting story and it shows how even when something is
Speaker 1: engineered to the highest levels and given multiple layers of
Speaker 1: redundancy and so on, things can still go sour. In
Speaker 1: step one, the earthquake happened, and this was fine. The
Speaker 1: four reactors that were nearest the epicenter of the earthquake
Speaker 1: detected the earthquake and they shut down automatic, just like
Speaker 1: they were supposed to. So what does shut down mean?
Speaker 1: If you were to look inside these nuclear reactors, you
Speaker 1: would see fuel rods filled with nuclear fuel little pellets
Speaker 1: about the size of your little finger that are arranged
Speaker 1: in these rods and collected together in bundles, and the
Speaker 1: control rods moved down between the rods to absorb neutrons
Speaker 1: that are coming out of the uranium atoms in the fuel.
Speaker 1: And once you absorb the neutrons, you basically quench or
Speaker 1: stop the nuclear reaction. That's creating the heat that's creating
Speaker 1: the steam that's creating the electricity for the power plant.
Speaker 1: So they automatically shut down the control rods moved into
Speaker 1: the reactor core, absorbed all the neutrons quen the reaction.
Speaker 1: Now there's still some, well not some, a lot of
Speaker 1: residual heat in that reactor core, both from other radioactive
Speaker 1: elements of short life that are in the core before
Speaker 1: it's quenched, and also just the heat that had accumulated.
Speaker 1: You can't have a gigawatt power plant with you know,
Speaker 1: a light bulb as that. Here, you have a giant
Speaker 1: mass of something that's hot and it's it's itself is
Speaker 1: going to take time to cool down. So the earthquake happened,
Speaker 1: nothing happened to the buildings. They were engineered properly and
Speaker 1: and sustained no damage in the earthquake. The reactors shut
Speaker 1: down and everything was fine. So now you have these
Speaker 1: big nuclear reactors which are in the process of cooling down,
Speaker 1: which is gonna take some time. And during that cooling
Speaker 1: down process you need to circulate cooling water through the cores. Unfortunately,
Speaker 1: the power grid wasn't in such great shape and so
Speaker 1: power failed to the nuclear power plants, and you would
Speaker 1: think this wouldn't be the big problem, since they are
Speaker 1: power plants after all, but they had been shut down automatically,
Speaker 1: so they aren't producing electricity. So in this situation where
Speaker 1: your nuclear power plant is shut down and you have
Speaker 1: lost the connection to the power grid, what they've got
Speaker 1: is on site backup diesel generators. So these diesel generators
Speaker 1: fired up to provide power that would run the pumps
Speaker 1: that would keep these cores cool. That system worked properly
Speaker 1: and everything was fine until the tsunami hit. And normally
Speaker 1: a tsunami hitting a nuclear power plant wouldn't be a
Speaker 1: big deal because they know about tsunamis and had designed
Speaker 1: against them. But they had not expected this big of
Speaker 1: a tsunami, so when it hit, it basically inundated the
Speaker 1: diesel generators, all of them, and took them out of service.
Speaker 1: Now you could argue that the engineers should have put
Speaker 1: the diesel generators up higher so they couldn't have gotten
Speaker 1: hit by a tsunami, or they should have made the
Speaker 1: diesel generators submersible so even if the tsunami came, they
Speaker 1: could run submerged and keep power going. But neither of
Speaker 1: those things happened, so the diesel generators failed. Now, in
Speaker 1: a nuclear power plant, there's another backup system which involve
Speaker 1: alves batteries, and batteries are there in case the diesel
Speaker 1: generators fail so that you have time to get some
Speaker 1: kind of additional backup plan in place. But these are batteries.
Speaker 1: Think about how batteries are in your life. They're always
Speaker 1: going dead, they never last long enough. If they're fully charged,
Speaker 1: you're you're still subconsciously thinking about them going dead. And
Speaker 1: batteries at a nuclear power plant are no different. These
Speaker 1: were designed to have a lifespan of about eight hours.
Speaker 1: So the batteries are circulating cooling water through the cores
Speaker 1: and everything's fine, And meanwhile the engineers are trucking in
Speaker 1: backup backup diesel generators to puck into the nuclear power
Speaker 1: plants and fire them up. But when these when these
Speaker 1: backup backup generators arrived, apparently they had the wrong plugs
Speaker 1: on them. They weren't quite compatible with the nuclear power plant,
Speaker 1: according to some reports, and they couldn't just be hooked
Speaker 1: in instantly, which meant that the batteries went dead. And
Speaker 1: this is where things started to come unraveled without cooling
Speaker 1: water circulating through the core, the reactor core starts to
Speaker 1: heat up and it starts to boil the cooling water,
Speaker 1: and as that water boils off, it starts to lower
Speaker 1: the level of water in the reactor core, causing some
Speaker 1: of the clear fuel rods to not be submerged in
Speaker 1: water anymore. At this point, the fuel rods overheated and cracked,
Speaker 1: allowing water to get into the very very hot nuclear
Speaker 1: pellets and you get dissociation of the water molecules and
Speaker 1: the production of hydrogen. It builds up in pressure and
Speaker 1: it has to be vented off, and that normally wouldn't
Speaker 1: be a problem. Factories vent gases all the time, but
Speaker 1: for some reason, when they vented off a large quantity
Speaker 1: of hydrogen gas, it ignited and exploded, and this caused
Speaker 1: the building around the reactor vessel to disintegrate. Basically, the
Speaker 1: whole top of it was blown off by the hydrogen explosion.
Speaker 1: And this occurred multiple times, apparently at multiple plants. Now,
Speaker 1: if this process had been allowed to continue, the process
Speaker 1: of boiling the cooling water off and exposing more and
Speaker 1: more of the core, things would have gone from bad
Speaker 1: to worse because eventually the nuclear fuel pellets would get
Speaker 1: so hot that they would melt. And this is where
Speaker 1: the word meltdown comes from. The idea that the nuclear
Speaker 1: fuel heats up, melts and becomes what one article termed
Speaker 1: radioactive lava that flows to the bottom of the reactor
Speaker 1: vessel and potentially each through it and ends up in
Speaker 1: the floor of the reactor containment building. To prevent that
Speaker 1: from happening. To prevent a meltdown, the technicians in Japan
Speaker 1: decided to start pumping seawater into the reactors. And this
Speaker 1: is largely a desperation measure because the seawater ruins the
Speaker 1: reactor and you're not ever going to be able to
Speaker 1: to fix it. You're gonna have to scrap the whole
Speaker 1: thing and start over. So they start pumping seawater in
Speaker 1: and that prevents a meltdown. Long term, that's going to
Speaker 1: have some serious consequences for the whole nuclear industry in
Speaker 1: Japan and for the Japanese Power Group, because nuclear power
Speaker 1: is an important part of the power system in Japan.
Speaker 1: It makes up you know, these failed reactors make up
Speaker 1: something like fifteen percent of the whole electricity generating capacity
Speaker 1: of the country and that's a big loss for a
Speaker 1: country to sustain and will have to be replaced both
Speaker 1: short term and long term. So what does this whole
Speaker 1: episode mean in real terms? That depends on how you
Speaker 1: want to spin it. So if you don't like nuclear power,
Speaker 1: the way you spin this is you say, look, these
Speaker 1: terrible things happened. These were supposed to be well engineered systems,
Speaker 1: but clearly they were not. There was radiation that was
Speaker 1: released into the environment, there were explosions, there could have
Speaker 1: been a meltdown. Things just did not go as we
Speaker 1: were are told they were go. Would go in an
Speaker 1: engineer system like this, Nuclear power should not be allowed
Speaker 1: anywhere on the planet. If you're pro nuclear, you'd spin
Speaker 1: it the other way. You'd say, well, these reactors were
Speaker 1: designed and engineered with redundant systems and with procedures to
Speaker 1: handle just about any possible scenarios. So a lot of
Speaker 1: stuff went wrong, and yet in the big picture, nothing
Speaker 1: seriously dangerous happened as a result of the problems that occurred. So, yes,
Speaker 1: a little bit of radiation was leaked into the atmosphere,
Speaker 1: but most of it is harmless, very short lived, and
Speaker 1: that which wasn't completely harmless happened to blow out to see,
Speaker 1: so it wasn't affecting any major population areas or anything
Speaker 1: like that. And there were no meltdowns and there were
Speaker 1: no you know, radioactive explosions like we had at Chernobyl,
Speaker 1: So nothing really bad happened. And even if the meltdown
Speaker 1: had occurred, it would have been okay because it would
Speaker 1: have been contained within the containment build thing and it
Speaker 1: wouldn't have been any big deal. You can kind of
Speaker 1: pick how you want to personally spend this event, whether
Speaker 1: you want to be pro nuclear or anti nuclear, or
Speaker 1: somewhere in between. Be sure to check out our new
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