Thursday 31 March 2011

Around the world: nuclear Power plants and nuclear Radiation

Hello fluffy Pandas,
The news that have reached us from Japan in recent weeks are certainly shocking and confusing for many of you. There were pictures of huge flood waves, buried buildings and roads, or homeless people looking for their relatives and their houses. In addition to all this, people are scared of something that you can neither hear, see, smell, nor taste: nuclear radiation. According to media reports, this is what is leaking from the nuclear power plant (NPP) in Fukushima as a result of the massive flood wave and subsequent explosions and fires that hit the area and caused terrible damage.
When large amounts of  nuclear radiation are released, the consequences are disastrous for people, animals and the environment in the immediate vicinity as well as hundreds of kilometres away from the initial leak. Even in Tokyo, which is 250 kilometres away from the power plant in Fukushima, increased nuclear radiation has been registered in the air and the drinking water.
What is this nuclear radiation? What is a nuclear power plant and why is it dangerous? To make the current news a little bit more understandable, I will attempt to explain the terms
Nuclear Power Plants and Nuclear Radiation
today, as well as the terms and dangers that are associated with them.
What is radioactive material?
Any material that you can see or touch is made up of particles called atoms. Atoms are extremely small and therefore not visible to the naked eye.


Atoms whose inner parts, the atomic nuclei (1), split into even smaller parts under certain circumstances, are called ‘radioactive’. The splitting of the atomic nucleus is called nuclear fission. Usually, the substances uranium or plutonium are used for a nuclear fission. During a nuclear fission, great amounts of energy are released along with nuclear radiation.


Is nuclear radiation dangerous?
In higher doses, yes. Nuclear radiation can destroy small parts (cells) that our bodies are made up of. But there are different levels of nuclear radiation. If a body makes contact with a low level of radioactivity, it is not dangerous. A medium level of radioactivity in a body can lead to headaches, fever, nausea and other illnesses. A high level will lead to the destruction of internal organs. This can cause serious illnesses or even lead to death. Not only people and animals get hurt, but also our environment is damaged through a high level of nuclear radiation. Radiation can spread into the ground and the sea via drinking water or rain and contaminate plants and fish. Normally, nuclear radiation does not just leak out from somewhere, but is confined to the nuclear reactor of a NPP (Nuclear Power Plant).
What are nuclear power plants?
Nuclear fission with the subsequent freeing of energy that is later converted into electricity, is what happens in nuclear power plants. This is what a nuclear power plant looks like from the outside:
The big towers (2) are called cooling towers. The generation of electricity happens with the help of radioactive substances in a smaller tower (3), which is called reactor block. This is what it looks like on the inside:
The radioactive substances are in the nuclear fuel rods (4). Here the radioactive material is broken down and electricity is created. In this process, a vast amount of energy is released, so that the water surrounding the nuclear fuel rods  is heated up significantly. The resulting water vapour powers turbines that produce electricity. To keep the nuclear fuel rods from overheating, they have to constantly be supplied with cooling water (5).
The nuclear power plant in Fukushima consists of six such reactors. Because of the impact of the tsunami, the cooling systems in several reactors have failed. That means that the water can no longer cool the nuclear fuel rods with their radioactive substances and the rods therefore overheat dramatically. Over the course of the last few weeks, people have tried to cool the nuclear fuel rods with sea water to prevent further explosions and a nuclear meltdown. According to latest reports, however, a nuclear meltdown has apparently happened despite the efforts.
What is a nuclear meltdown?
During a nuclear meltdown, the nuclear fuel rods overheat so much that they turn liquid. The result is a dangerous mix of nuclear material and metal. This mix is very high in nuclear radiation and essentially eats its way through the reactor. The dangerous substances seep into the drinking water or into the air through dangerous vapours. Winds can transport the nuclear radiation to far away places. This is the worst case scenario. That is why this process is also called ‘Beyond Design Basis Accident’ (BDBA). During the last BDBA in Chernobyl, nuclear radiation was measured even as far away as 1000 km and more from the actual incident.
In Japan, people are continuing to do everything in their power to prevent a Beyond Design Basis Accident. Firemen are cooling the reactor with fresh water now. The switch to fresh water was made because fresh water leaves behind fewer deposits and is less corrosive than sea water. They are also trying to remove the water that was contaminated with radiation, so that no more of this water will seep into the ground. There are also attempts to reestablish electricity to get the cooling systems to operate normally again. Unfortunately, it is not yet known how much nuclear radiation is leaking out at this point. For the people in Japan, I am hoping from the bottom of my heart that the damage stays as minimal as possible! Have you talked to your teachers or your parents about nuclear energy and other energy sources yet? Did you know that you can generate energy from wind, sun, water and even cow dung? Which energy source do you think is best? I am hoping for a lot of feedback from you!
Love & Peace
Kristina020

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