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There are six reactors at Japan's Fukushima Nuclear Power Plant, and three of them (numbers one, two and three) were operating at the time of the recent earthquake. All of these had all their control rods dropped in right after the earthquake struck. This shut down those reactors. The problem is that the operating reactors had been operating at high power for some time before shutdown. And this left a large amount of fission products in the fuel element in the cores of these reactors when they shut down.
The fission products of nuclear fission reactions are largely radioactive, and they generate a lot of thermal energy as they decay. It is decay heat that must be removed from a reactor that has just been shut down to keep it cool and prevent it from melting down. The control rods can do nothing to stop decay heat from the fission fragments, and cannot cool the core after shutdown. Only coolant and circulating pumps and heat exchangers can do this. But the tsunami knocked out power to the plant and damaged the emergency generators that provide the plant with back-up power. The cores overheated, went into meltdown, and the dominos continue to fall.
What else can I help you with?
What caused the nuclear reactor to begin to melt down in japan?
the cause of the melt down of the reactors in japan is the water that is needed to cool down the reactors
What does lower control rods result in?
Lowering control rods into a nuclear reactor results in reducing the number of nuclear fission reactions occurring in the reactor core. This process helps to regulate the power output of the reactor by absorbing neutrons and decreasing the rate of nuclear reactions.
How are nuclear reactors kept safe?
There are many safety procedures put in place to keep a nuclear reactor safe, first of all control rods are used inside the reactor to stop the fission reaction running out of control and melting the reactor core, constant water(coolant) is kept pumping around the reactor cool and to help soak up some of the neutrons and x-ray scans are used to check that there are no natural cracks inside the reactor.
How did the Nuclear reactor get damiged?
If you are talking about the Nuclear Reactors in Japan, they were damaged because when they lost power, the water pumps used to cool them stopped, and all of the nuclear material overheated.
How long does it take a nuclear reactor rod to cool down?
It can take anywhere from several years to several decades for a nuclear reactor rod to cool down to a level where it can be safely removed from the reactor core and stored. Cooling times vary depending on the type of reactor and the specific isotopes present in the fuel rod.
Is Japan cool?
not cool
Does the water used to cool a nuclear reactor get contaminated?
In a properly operating nuclear reactor, water used to cool the reactor is not contaminated. This water, called primary coolant, is quite pure. And after shutdown and cooldown, the water has little radiation in it. But if the reactor has some malfunction that overheats the fuel, fuel elements can rupture or melt (a meltdown) and fission products, which are hightly radioactive, can be released into the coolant (the water). The water is then contaminated.
What is used in nuclear power stations to cool the reacants down?
Water is commonly used to cool the reactor in nuclear power stations. This water absorbs the heat generated by the nuclear reactions and carries it away, preventing the reactor from overheating. The cooled water is then circulated back to the reactor to continue the cooling process.
How is Japan different to New Zealand?
New Zealand is more skuxx aka cool but Japan has cool cars
How long does it take a nuclear reactor to cool?
The time it takes to cool a nuclear reactor down varies. If a reactor has been running at nearly full power and is shut down, it takes several days to even weeks to cool it down. The size of the reactor and the "aggressiveness" of a cooling system will affect the cooldown time as well as the power levels at which the reactor was operating at before shutdown. If a reactor has been operating for some time at high power and is shut down, fission in the core stops (as it does in any shutdown). But fission products in the core are at a high level because the reactor was operating at high power. These fission products will continue to decay for some time. The decaying fission products will be creating a lot of residual heat for this extended period, too.
Why does Japan have an interesting history?
Japan has cool mochi
Are generation 3 nuclear plants safe?
Most nuclear power plants are quite safe. The only ones that were inherently unsafe ware the Soviet-made power stations similar to Chernobyl, which did not include a reactor containment building. The nuclear powerplant at Fukushima Daichi in Japan was crippled not by a failure of the nuclear reactor, but by the tsunami following the magnitude 9+ earthquake. The plant survived the earthquake, and the plant operators shut down the reactor, but a nuclear reactor generates a LOT of heat, and takes a while to cool off. When the reactor isn't providing power to run the coolant pumps, external power must be supplied to run the pumps to cool the reactor. Fukushima Daichi had backup diesel generators for this purpose, and power from the electrical grid as a backup - but the tsunami knocked out the generators and knocked down the power grid all along the coastline. The new reactor designs are not susceptible to failure when the coolant pumps go offline.
