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Non-Renewable Energy- Nuclear Sources (Nuclear Sources: (A nuclear power…
Non-Renewable Energy- Nuclear Sources
Nuclear Sources:
A nuclear power plant is a highly complex and expensive machine designed to boil water to produce steam that spines a turbine to produce electricity
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Nuclear fission reaction
- nuclei of certain isotopes with large mass numbers (uranium-235) are struck by a neutron
- splits the heavy nucleus apart into lighter nuclei and release energy
Chain reaction
- can also release neutrons, which fly out and cause more nuclei to fission
- those nuclei split, releasing more energy and more neutrons which go on to split more nuclei and so on
this cascade of fission can result in a chain reaction that releases an enormous amount of heat energy in a short time
Nuclear fuel: the fuel for a nuclear reactor is made form uranium ore which is mined from the earth's crust
Uranium is common in rich and seawater, it's the enrichment and reactor technology that is hard ti com by (expensive)
Nuclear meltdown:
- The danger of nuclear reactors comes from smaller explosion that can release radioactive material into the environment or cause a core meltdown because of a loss of coolant water
- a coolant, usually water, circulates through the reactor's core to remove heat and keep the fuel rods and other reactor components from melting and releasing massive amounts of radioactivity into the environment
- a containment shell made of think, steel-reinforced concrete surrounds the reactor core to: 1. keep the radioactive materials from escaping into the environment, in case there is an internal explosion or a core meltdown 2. protect the core from outside threats like hurricanes and attacks
(probabilities of a nuclear meltdown are extremely low)
The nuclear fuel cycle
-building a nuclear power plant
-mining the uranium
-processing and enriching the uranium to make fuel
-using it in a reactor
-safely storing the resulting highly radioactive wastes fro thousands of years until their radioactivity falls to safe levels
-Retiring the worn-out plant by taking it part and storing its high and moderate-level radioactive part safely for thousand of years.
Advantages of Nuclear Power Low CO2 emissions, no toxic emissions, as long as a reactor is operating safely, the power plant itself has a low environmental impacts and a low risk of an accident
Disadvantages of Nuclear power
- nuclear fuel has the highest energy density of all practical sources. high cost of building the plant and operating the nuclear fuel cycle>low net energy
- Nuclear power cannot compete in the marketplace with other energy resources such natural gas, wind. and solar cells unless it is heavily subsided by governments
- Threat of nuclear weapons: enrichment and nuclear reactor tech/expertise can bu used to produce bomb-grade uranium and plutonium for use in nuclear weapons
NUCLEAR WASTE
Nuclear Waste
the enriched uranium fuel in a typical nuclear reactor lasts fro 3-4 years, after which it becomes spent or useless and must be replaced
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reprocessing spent nuclear fuel rods reduces the storage time for the remains wastes from up to 240,000. The reprocessing is expensive and produces bomb-grade plutonium that can be used by nations to make nuclear weapons
Scientist and engineers agree in principle that deep burial in an underground repository is the safest and cheapest way to stope high-level radioactive wastes for thousand of years
Decommissioned- when a nuclear reactor reaches the end of its useful life after 40 to 60 years
3 ways to do this according to scientist and engineers:
- Remove and store the highly radioactive parts in a permanent, secure repository (does not exist yet)
- Install a physical barrier around the plant and set up full-time security for 30 to 100 years before dismantling the plant and storing its radioactive part in a repository
- enclose the entire plant in a concrete and steel-reinforced tops called a containment structure
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