Nobody wants a radioactive plume dispersing killer particles across the globe. It happened once (Chernobyl) and people are freaked that it's gonna happen again in Japan. Since the deadly Soviet bungle, reactors have gotten safer—but are they safe enough?
Yes, the situation in Fukushima is dire and always seems like it's getting worse, but those Japanese reactors were state of the art when they were built. The good news is that there are already nuclear power plants on the ground that are significantly less susceptible to damage. The better news that there are plants in the works that are even safer. Much of the focus of nuclear power R&D is on safety, and this is a good thing—nuclear power isn't something we should be giving up on.
The world's most advanced operational reactors, called the third generation, started popping up in Japan in 1996 (unfortunately, almost a decade after the newest of Fukushima Daini's reactor was put in place) and are designed to withstand an arsenal of man or earth-made assaults.
When these upgraded nuclear structures are pitted against, for instance, the direct impact of a jetliner, the structure wins. In fact, the plane doesn't stand a chance. They fair better in earthquakes, too, and have streamlined systems that make them less susceptible to operational issues like the ones plaguing the Tokyo Electric Power Company. Overall safety features in newer models are passive: They implement "core-catchers"-systems designed to contain full-scale meltdowns; they rely on convection, gravity and resistance to high temperatures in a pinch instead of on things that might fail, like power.
A lot of the problems Japan is dealing with in their four troubled reactors have already been corrected. In fact, there are only four next-gen nuclear reactors currently in operation, and they're all in Japan. Sure, Taiwan is working on getting the same upgrades that Japan has-what's called advanced boiling water reactors-and the US has licensed the design, but ABWRs, considering what's on offer all over the world, isn't even at the forefront of technology. Remember, Japan got their first one in the mid-nineties.
China is currently invested in the AP1000 reactor, which is considered Gen III+, or the honors class version of these new energy plants. In an event that a coolant pipe bursts, this reactor takes care of the problem without needing operator intervention, pumps, or ac power. If the temperature gets too high, gravity funnels water in from a cooling from a tank above the reactor. It is one of those, as mentioned before, that passively mitigates serious issues.
There are a slew of others that strive for the same. The Kerena, out of Germany, has a core catcher that allows the hazardous nuclear fuel to stay sealed-off and safe from the world in the event of a total meltdown. ACR, currently waiting for certification in Canada, has two independent fast shutdown systems as well as a slew of other passive safety measures. The next decade, if not overwhelmed by current concerns, should see a lot more of these.
At the same time, companies and governments all over the planet are brainstorming the far future. While generation three reactors polish up an older standard, the fourth group of plants will see a total redesign. Uranium will be swapped for the depleted stuff and sodium or helium could replace water as a coolant.
SAFEST PLANTS | Taiwan is planning an advanced boiling water reactor (ABWR) that has improved earthquake response and passive containment cooling. It has also dumped external recirculation systems, which simplified the design.
China started construction on the world's first Westinghouse-made AP1000 reactor in 2009. China estimates that their generation three reactors will have a 100-fold increase in probable safety compared to their generation two reactors thanks to streamlined operations and passive safety measures.
The Advanced Power Reactor 1400 (APR1400) is scheduled to open for commercial operation in South Korea in 2013. It has upgraded safety features, like better earthquake resistance due to the plant's layout, and the EU version will have a core-catcher to help in the case of an unlikely meltdown.
Even further on the horizon is the traveling wave reactor developed by Intellectual Ventures, Nathan Myhrvold's ideas company. This reactor would run off depleted uranium, but the idea is still in its infancy. They are currently gauging the interest of governments and companies to license the design because they don't plan on building it themselves.
New technologies take time to implement. There are, as you can imagine, a huge amount of regulatory hoops to jump through with nuclear power. And as strict as safety measures are now, they will surely get tougher in light of recent events.
The four boiling water reactors of the Fukushima Daini nuclear power plant were built in 1982, 1984, 1985 and 1987, respectively. They're Second Generation facilities with some upgrades (basically what you can expect from reactors in operation in France or the US). They're built directly on bedrock, which makes them more resistant to quakes; the buildings are shaped like squares, a shape which has proven particularly adept at resisting shaking.
And on the inside: The radioactive material is encased in ceramic pellets that guard against corrosion and heat-up to 3,000° C. Three hundred and sixty of those pellets are then sealed in a 13-foot metal tube that's rated to withstand temperatures up to 2,200° C. Next, there's the pressure vessel, which is a 6-inch-thick steel barrier that holds the core power reactor and is topped by the primary containment vessel which is an additional inch and a half-thick. The outer concrete walls—the fifth layer of protection around the reactor—are five feet thick. It's among the most heavily protected lock down facilities in the world. These five layers make up the container, which is a very benign word for the thing that Chernobyl didn't have—and the thing that people fear will spring a major leak.
When shaking does occur, and seismic detectors within the reactor register anything above a 5.0, the reactor automatically shuts down by inserting rod into the core to stop the nuclear fission. This did happen in Japan. Water should continue to circulate even after an earthquake in order to keep the fuel rods' temperature down, but because of a power outage also caused by the quake, that system failed. That's why plants like Fukushima employ backup diesel generators to spray the rods with coolant. That happened for about an hour before the tsunami hit, washing away the generators. After that, safety system number three, which converts the steam created when the hot core evaporated the cooling water back into water in order to keep the reactor from overheating, clicked into place. Unfortunately, it had to work for too long: The water level sank, and the rods started to heat up. Right now the Tokyo Electric Power Company is still trying to get this heating under control.
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This three-tiered failure of the Fukushima Daini reactors would not have happened in next gen models. A silver lining-if any-to this disaster is that it's an invaluable test of what was once the state of the art, and that the lessons learned in Fukushima will help usher in even safer reactors in the future. If we live that long.