The Crisis at Three Mile Island essays

The Crisis at Three Mile Island essays In Middletown, PA, a quiet rural community, sits the nuclear power plant at Three Mile Island, better known as TMI. It was at this station that the worst commercial nuclear accident in the country's history occurred. Early in the morning of March 28, 1979, during routine operations a false reading on a valve caused the hot nuclear core of the reactor to be without water to cool it. The operators also wrongly thought the cooling system was full. The opposite was true. The core began to melt and build up of hydrogen took place in the building that housed it. The fear was that the nuclear core would melt through the floor and contaminate all the groundwater for miles around. Also, it was feared that the hydrogen would spark an explosion which would devastate the area. Government officials struggled all day on March 28th and 29th to size up the scope of the accident. The governor ordered all pre-school children and pregnant women to be evacuated from areas in proximity to the plant. Through careful analysis, the operators and government experts were able to bring the reactor to a cold, stable, but unstable condition. By April 4th, the people who were evacuated began to return. However, life for the plant and the industry that spawned it was forever changed. Protests abounded as the cleanup began. Officials wanted to vent what they claimed were small amounts of radioactive gas. There was also strong opposition to the transport of nuclear waste from the site. A plant that had once hosted tours and ran an observation site was now off limits and patrolled by armed security forces. The value of land in the area plummeted as peopled feared contamination. Today this issue still rages within the scientific community. Government scientists claim there was no significant environmental or genetic damage to the area of its residents. Conversely, groups such as the Union of Concerned Scientist point to private studies showing an increase in...

How Neon Lights Work (A Simple Explanation)

How Neon Lights Work (A Simple Explanation) Neon lights are colorful, bright, and reliable, so you see them used in signs, displays, and even airport landing strips. Have you ever wondered how they work and how different colors of light are produced? Key Takeaways: Neon Lights A neon light contains a tiny amount of neon gas under low pressure.Electricity provides energy to strip electrons away from neon atoms, ionizing them. Ions are attracted to terminals of the lamp, completing the electric circuit.Light is produced when neon atoms gain enough energy to become excited. When an atom returns to a lower energy state, it releases a photon (light). How a Neon Light Works A neon light consists of a glass tube filled with a small amount (low pressure) of neon gas. Neon is used because it is one of the noble gases. One characteristic of these elements is that each atom has a filled electron shell, so the atoms dont react with other atoms and it takes a lot of energy to remove an electron.There is an electrode at either end of the tube. A neon light actually works using either AC (alternating current) or DC (direct current), but if DC current is used, the glow is only seen around one electrode. AC current is used for most neon lights you see.When an electric voltage is applied to the terminals (about 15,000 volts), enough energy is supplied to remove an outer electron from the neon atoms. If there is not enough voltage, there will not be enough kinetic energy for the electrons to escape their atoms and nothing will happen. The positively charged neon atoms (cations) are attracted to the negative terminal, while the free electrons are attracted to the pos itive terminal. These charged particles, called plasma, complete the electric circuit of the lamp. So where does the light come from? Atoms in the tube are moving around, hitting each other. They transfer energy to each other, plus a lot of heat is produced. While some electrons escape their atoms, others gain enough energy to become excited. This means they have a higher energy state. Being excited is like climbing a ladder, where an electron can be on a particular rung of the ladder, not just anywhere on its length. The electron can return to its original energy (ground state) by releasing that energy as a photon (light). The color of the light that is produced depends on how far apart the excited energy is from the original energy. Like the distance between rungs of a ladder, this is a set interval. So, each excited electron of an atom releases a characteristic wavelength of photon. In other words, each excited noble gas releases a characteristic color of light. For neon, this is a reddish-orange light. How Other Colors of Light Are Produced You see lots of different colors of signs, so you might wonder how this works. There are two main ways of producing other colors of light besides the orange-red of neon. One way is to use another gas or a mixture of gases to produce colors. As mentioned earlier, each noble gas releases a characteristic color of light. For example, helium glows pink, krypton is green, and argon is blue. If the gases are mixed, intermediate colors can be produced. The other way to produce colors is to coat the glass with a phosphor or other chemical that will glow a certain color when it is energized. Because of the range of coatings available, most modern lights no longer use neon, but are fluorescent lamps that rely on a mercury/argon discharge and a phosphor coating. If you see a clear light glowing in a color, its a noble gas light. Another way to change the color of the light, although its not used in light fixtures, is to control the energy supplied to the light. While you usually see one color per element in a light, there are actually different energy levels available to excited electrons, which correspond to a spectrum of light that element can produce. Brief History of the Neon Light Heinrich Geissler (1857) Geissler is considered the Father of Fluorescent Lamps. His Geissler Tube was a glass tube with electrodes at either end containing a gas at partial vacuum pressure. He experimented arcing current through various gases to produce light. The tube was the basis for the neon light, mercury vapor light, fluorescent light, sodium lamp, and metal halide lamp. William Ramsay Morris W. Travers (1898) Ramsay and Travers made a neon lamp, but neon was extremely rare, so the invention was not cost-effective. Daniel McFarlan Moore (1904) Moore commercially installed the Moore Tube, which ran an electric arc through nitrogen and carbon dioxide to produce light. Georges Claude (1902) While Claude did not invent the neon lamp, he did devise a method to isolate neon from air, making the light affordable. The neon light was demonstrated by Georges Claude in December of 1910 at the Paris Motor Show. Claude initially worked with Moores design, but developed a reliable lamp design of his own and cornered the market for the lights until the 1930s. Make a Fake Neon Sign (no neon required)