Please enable JavaScript.
Coggle requires JavaScript to display documents.
7.3 Nonrenewable energy- nuclear sources (Disadvantages of Nuclear power,…
7.3 Nonrenewable energy- nuclear sources
Nuclear power is a highly complex and costly system designed to perform a relatively simple task: boil water to produce steam that spins a turbine and generates electricity
It creates hat by a control nuclear fission reaction
Nuclear fission reaction: Nuceli of certain isotopes with large mass numbers are struck by a neutron, this splits the eheavy nucleu apart into lighter and releases energy
Chain reaction: this fission also releases netrons, which fly out and casue more nuclei to fission. Those nuclei split too, releasing more energy and more neutron which go on to split to more nuclei and so one
This takes place in the core of a reactor
The fuel for a nuclear reactor is made from uranium ore which is mined from the earth's crust
Uranium is actually pretty common in rocks and seawater- it's the enrichment and reactor technology that is hard to come by beacause it's expensive
Only 1 percent of uranium is fissionable.
The enriched uranium-235 is processed into small pellets of uranium dioxide. Large numbers of the pelletes are packed into closed pipes, called fuel rods, which are then grouped together in fuel assemblies, to be placed in the core of a reactor
Nuclear meltdown
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
The nuclear reactor cannot explode like an atomic bomb and cause massive damage. The danger in culear reactors comes from smaller explosions that can release radioactive materials into the environments or cause a core meltdown because of a loss of coolant water
a containment shell made of thick, steel-reinforced concrete surrounds he reactor core to
Help keep 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 is extremely low
The Nuclear fuel Cycle
Building a nuclear power
Mining the uranium
Processing and enriching the uranium to make fuel
Using it in a reactor
Safely storing the resulting highly radioactive wastes for thousands of years until their radioactivity falls to safe levels
Retiring the worn-out plant y taking it apart and storing its high- and moderate- level radioactive parts safely for thousands 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 impact and a low risk of an accident
Disadvantages of Nuclear power
Nuclear fuel has the hghts energy density of all practical fuel sources. However, high cost of building the plant and operating the nuclear fuel cycle = low net energy
So low, nuclear power cannot compete in he marketplace with other energy sources such as natural gas, winds, and soon from solar cells unless it is heavily subsidized by governments
Threat of Nuclear weapons: enrichments and nuclear reactor tech/expertise can be used to produce bomb-grade uranium and plutonamium for use in nuclear weapons
Nuclear waste
The enriched uranium fuel in a typical nuclear reactor lasts for 3-4 years, after which it becomes spent, or useless, and must be replaced
Spent fuel rods are so thermally hot and highly radioactive that they cannot be simply thrown away
Another costly radioactive waste problem arises when a nuclear reactor reaches the end of its useful life after about 40 to 60 years and must be decommissioned
Scientist and engineers have proposed three ways to do this:
Remove and store the highly radioactive parts in a permanent, secure repository
Install a physical barrier around the plant and set up full-time security for 30 to 100years before dismantling the plant and storing its radioactive pars in a repository
Enclose the entire plant in a concrete and steel-reinforced tomb, called a containment structure
Nuclear fusion-future energy?
Other proponents of nuclear power hope to develop nuclear fusion-in which the nuclei of two isotopes of a light element such as hydrogen are forced together at extremely high temperatures until they fuse to form a heavier nucleus, releasing energy in the process
The sun uses nuclear fusion to warm the earth and sustain its life. successful, controlled nuclear fusion to warm the earth will provide an almost limitless source of energy