One doesn’t need to be a scientist to understand how nuclear fuel creates electricity or why “spent” nuclear fuel rods are dangerous. (I use the word "spent" loosely, as it would indicate spent fuel rods have little-to-no energy or radioactive contents, which is not the case). If you have been searching for a basic explanation about what is happening in Japan’s nuclear power plants, search no more. Your long journey has finally come to an end!
UNDERSTANDING HOW NUCLEAR ENERGY IS CREATED
In order to create electricity, fuel is required. The fuel being utilized in Japan's nuclear power plants is uranium, a radioactive, chemical metal. Small pellets of uranium are stacked inside a metal rod (referred to as a fuel rod). The rods are composed of zirconium and grouped together inside of a containment vessel. Once inside the containment vessel, a controlled reaction begins in order to produce energy.
A nuclear power plant is designed to control the reaction so the reaction does not result in an explosion. The controlled reaction produces heat. The heat boils water. The boiled water creates steam. The steam is what causes the turbines to spin. The spinning turbines create electricity.
There is a process to stop the controlled reaction by inserting control rods into the containment vessels. Once the control rods are placed among the reacting nuclear fuel rods, the reaction is stopped.
WHY IS THERE STILL A DANGER IF THERE ARE CONTROL RODS?
Even though control rods have stopped the nuclear reaction, the nuclear fuel rods are still extremely hot and contain radioactive material (uranium) inside of the rods. In order to keep the rods cool, water must be used, and the water must be constantly circulating; otherwise, the result is boiling water which will, eventually, burn down much like a pot of boiling water.
Once the water is gone and the nuclear fuel rods are exposed to air, the zirconium rods begin to break down and release radioactive uranium into the atmosphere.
The containment vessels, in Japan’s nuclear power plants, happen to be located just below the roof of the building. As you can see from the footage aired on television, there are wide, gaping holes in many of the nuclear power plants. This is why we are witnessing water being sprayed onto the nuclear power plants in Japan. The damage caused by the earthquake and tsunami resulted in, essentially, the cooling system to fail.
WHAT ARE SPENT NUCLEAR RODS?
The life of a nuclear fuel rod is approximately six years, at least in terms of efficient energy. In order to make sure that a nuclear power plant runs efficiently, nuclear fuel rods have a life expectancy of six years. This does not mean that the nuclear fuel rods are no longer hot (they are!), and this does not mean that the nuclear fuel rods no longer contain radioactive uranium (they do!). It simply means that the power plant must replace the older nuclear fuel rods, called spent nuclear fuel rods, with newer nuclear fuel rods in order to maintain an efficient supply of electricity.
Spent nuclear fuel rods are placed inside a pool of water in order to cool down the rods (so the metal doesn’t break down). The water also acts as a sort of shield for the workers inside of the nuclear power plant, protecting the workers from radiation exposure. Again, the water must be constantly circulating; otherwise, the water will boil away, expose the nuclear fuel rods, and the zirconium will begin to disintegrate, releasing radioactive material into the atmosphere.
It takes anywhere from five to ten years to cool down a spent nuclear fuel rod. After the spent nuclear fuel rod has been cooled down enough to be removed from the pool of water, the spent fuel rods are stored in concrete and steel casks in locations all around the world. Even though the spent nuclear fuel rods are no longer hot enough to break down the zirconium, the material inside is still radioactive.
So, not only are we witnessing Japan’s containment vessels releasing radioactive material into the atmosphere, but there are also the spent nuclear fuel rods to worry about as well. The pools holding the spent nuclear fuel rods do contain leaks because of the damage from the earthquake, and this is why radioactive material is being released into the ocean.
I don’t know about you, but nothing about this process makes me think that nuclear energy is “green” energy.