Addendum to Nuclear Power Uranium235 Uraninium Uranium is
- Slides: 8
Addendum to Nuclear Power
Uranium-235 Uraninium • Uranium is a fairly common element on Earth, incorporated into the planet during the planet's formation. Uranium-238 (U-238) has an extremely long half-life (4. 5 billion years), and therefore is still present in fairly large quantities. U-238 makes up 99 percent of the uranium on the planet. U-235 makes up about 0. 7 percent of the remaining uranium found naturally. Uraninium-235 • Because Uranium-235 is able to undergo induced fission, it useful for both nuclear power production and for nuclear bomb production. – If a free neutron runs into a U-235 nucleus, the nucleus will absorb the neutron without hesitation, become unstable and split immediately. Induced fission
Nuclear Power • Nuclear power plants provide about 17 percent of the world's electricity. – In France, about 75 percent of the electricity is generated from nuclear power. – In the United States, nuclear power supplies about 15 percent of the electricity overall, but some states get more power from nuclear plants than others.
Enrichment • A sample of uranium must be enriched so that it contains 2 percent to 3 percent or more of uranium-235. – Three-percent enrichment is sufficient for use in a civilian nuclear reactor used for power generation. – Weapons-grade uranium is composed of 90 -percent or more U-235.
Nuclear Power Plant • • • Typically, the uranium is formed into pellets with approximately the same diameter as a dime and a length of an inch. The pellets are arranged into long rods, and the rods are collected together into bundles and submerged in water inside a pressure vessel. – In order for the reactor to work, the bundle, has to have the tendency to overheat and melt. – The water acts as a coolant. To prevent the overheating, control rods made of a material that absorbs neutrons are inserted into the bundle using a mechanism that can raise or lower the control rods. – Raising and lowering the control rods allow operators to control the rate of the nuclear reaction.
Reactor & Control Rods
Nuclear Power Plant, cont The uranium bundle in the reactor acts as an extremely high-energy source of heat. It heats the water, creating steam, which drives a steam turbine, spinning a generator to produce power.
Can you answer all of these? • Where do you find the coolant? • Where do you find the moderator? What does it do? What is it usually made of? • What is released from the cooling tower? • What is the containment structure made of? • What is a half-life? Why is it important? • Besides, U-235, which other element is used in nuclear reactors?
