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Sunday, May 19, 2013
Nuclear EnergyPosted Sunday, February 7, 2010, at 4:08 PM
Virtually all electrical current is made by spinning a magnet inside a coil causing electrons, and "waves" to move down a wire. (Lightning is static electricity).
The most common way of spinning the magnet is with a turbine pushed by steam. Conventional power plants burn coal, oil, or gas to boil water to make the steam to turn the turbine. Nuclear plants generate steam from the heat byproduct of nuclear reactions.
Giving credit where credit is due, but for a friend who is a nuclear engineer, I would not know virtually any of the following information.
Uranium is an unstable element. When it is fully decayed, it becomes lead. Uranium is denser than lead, which is why the military uses depleted uranium as armor piercing ordinance. Depleted uranium has very little radioactivity.
What is the number one concern about nuclear power? Radiation leaks. How do nuclear power plants manage their radioactive material? Quite amazingly.
The fuel pellets, which contain 3-5 percent uranium 235, are encased in a protective rod, which prevents the escape of most types of radiation. Of course, the casing becomes incredibly hot from containing the radioactivity and heat from the fuel pellet, which in turn heats the water. The water is kept fully enclosed and under pressure. It is heated to an amazing 600-degrees. Because this water is unable to expand, and is not capable of turning into steam, it can be "super-heated."
This super-heated water is pumped to a heat exchanger where the heat is transferred to other water, which is then pumped to the turbines and allowed to turn into steam with explosive power.
The two bodies of water never come into direct contact with each other. Therefore, they never exchange any of the contaminants in them. Moreover, the area where the heat is generated and exchanged is encased in several layers of containment to "catch" any leaks.
What exactly is radiation and what is the danger? For this discussion, radiation is fundamentally the loss of photons and neutrons from the fissioning of atoms. Some atoms are unstable and lose these and other subatomic particles as they decay into more stable elements. These particles fly off at speeds near the speed of light. (Trust me, to an engineer, it is much more complicated than I just explained).
Being bombarded by these particles can cause cell damage in our bodies. It is exactly this process of UV radiation (a form of radiation similar to gamma radiation) exposure from the Sun that causes damage to our skin, which results in tanning. In fact, studies done by the Navy show that the crew that work on the deck of an aircraft carrier receive much more radiation from the Sun that the crew who work with the nuclear reactors.
Since virtually all of us are exposed to the Sun, what is the danger with radioactivity? People, such as X-ray techs and sun worshippers, can be bombarded too many times by radiation and suffer cell damage. People who either breathes in or swallow radioactive particles will have the part of the body where the particle is lodged bombarded by radiation and suffer cell damage. When cells are damaged, they can mutate and become cancerous.
For most of us, when we think of the danger of radioactivity from a nuclear power plant, it is the cancer, which can be caused by ingesting radioactive particles.
What is the number two concern about nuclear power? Nuclear waste.
The issue of nuclear waste is primarily an American problem. President Jimmy Carter issued an executive order, which is still in force, prohibiting the reprocessing of nuclear fuel. This was done to try to convince the Soviets that we would not threaten them by using our nuclear power plants as supply sources for nuclear bombs. I am not aware of any other nation, which declines to reprocess its spent nuclear fuel.
Over time, the nuclear fuel rod loses radioactivity, as the radioactive elements within them are fissioned and turned into neutron absorbing transuranic elements, which "poison" the reaction. Eventually, it becomes economically unviable to continue to use it to heat the water needed for power production as the amount of heat generated by them decreases. However, so long as there is Uranium or Plutonium, the material inside the road can still be used as fuel.
The concentrated U235 does not just get into the fuel rods. It was mined as ore and refined. The "spent" fuel rods can be refined again. Spent fuel rods contain about 1 percent U235 and 1 percent plutonium 239 (which is caused by the absorption of a neutron), depleted uranium, lead, and transuranic elements (the main source of harmful radiation in used fuel). Depleted uranium and lead do not need any particularly special storage. The active uranium and plutonium can be put back into fuel rods and used again. Modern, Generation 4, nuclear electric plants are designed for on-sight reprocessing and can actually burn the transuranic elements, eliminating the waste from current plants.
The United States is the only modern industrial nation on Earth which has not built a new civilian nuclear electric plant in the past 30 years. The last plant was in Rockport, Ind. However, in 1980, before construction was finished, it was closed. Eventually, it was converted into an operating coal fired plant.
Nuclear technology is much better these days than it was in the 1950s and 1960s, when the plants operating today were designed. Unfortunately, only the U.S. military gets to enjoy the benefit of this improved technology while we watch places like France become almost entirely powered by clean safe nuclear energy.