Nuclear Energy

AP Environmental Science

What Is It?!?

Low-Level Waste: is nuclear waste that does not fit into the categorical definitions for intermediate-level waste, high-level waste, spent nuclear fuel, transuranic waste, or certain byproduct materials known as 11e wastes


Transuranic Waste: is waste which has been contaminated with alpha emitting transuranic radionuclides possessing half-lives greater than 20 years and in concentrations greater than 100 nCi/g.


High-Level Waste: is a type of nuclear waste created by the reprocessing of spent nuclear fuel. It exists in two main forms: 1.) First and second cycle raffinate and other waste streams created by nuclear reprocessing. 2.) Waste formed by vitrification of liquid high-level waste


Half-Life: is the time taken for the radioactivity of a specified isotope to fall to half its original value.


Nuclear Waste: is radioactive waste material, for example from the use or reprocessing of nuclear fuel.


Nuclear Energy: is the energy released during nuclear fission or fusion.

Nonrenewable Mineral Resources

Nonrenewable Mineral Resource - Naturally occurring material in or on the earth’s crust that can be extracted and processed into useful materials at an affordable cost.


Areas where minerals are commonly found:

1) Along fault lines (areas of divergence or convergence – oceanic & continental crust) where magma has risen to the surface

2) Hot spots & Hydro-thermal vents (in the ocean)

3) Manganese nodules on the ocean floor because the heated water dissolves the minerals and deposits them nearby after cooling.

4) Sediment sorting – as sediments are carried along by the water they settle out based on their weight and the speed at which the water is flowing

5) Evaporate mineral deposits – nonmetallic minerals that have been dissolved by ground water are left in lakes that don’t have an outlet after the water has evaporated.

Dig for Extraction Here!

In the mineral process valuable minerals are concentrated by removing unnecessary substances from the Earth’s crust material. The first phase of the process involves reducing the size of the mineral. This is done in crushers and grinding mills where the ore is broken down into smaller pieces. When the fragments of ore are small enough, the pieces containing the most valuable minerals are separated from those containing mostly unneeded minerals. The separation process involves leaching, emission, gravity methods and magnetic separation. Water must also be extracted from the concentrated product. Coils, filters, thickeners, sedimentation basins and dryers are used to do this. After the extraction phase, the minerals still contain impurities, so they must be purified. The refining process uses heat, chemicals and electricity.


Harmful Effects:

  1. Unsightly workings
  2. Mineral waste piles
  3. Pollution of water by containing heavy metals

Two types of Nuclear Energy are Fission and Fussion

Rock & The Rock Cycle

Rocks are the solid mineral material forming part of the surface of the earth and other similar planets, exposed on the surface or underlying the soil or oceans.They are formed by the rock cycle which produces three main types of rocks, sedimentary, igneous, and metamorphic. This happens due to movements in the crust; rocks are frequently pulled under the surface of the earth, where temperatures increase dramatically the farther they descend. Between 100 and 200 kilometers (62 and 124 miles) below the earth's surface, temperatures are hot enough to melt most rocks. However, before the melting point is reached, a rock can undergo fundamental changes while in a solid state — morphing from one type to another without melting. An additional factor that can transform rocks is the pressure caused by tons of other rocks pressing down on it from above; heat and pressure usually work together to alter the rocks under the earth's surface. This kind of change, which results from both rising temperature and pressure, is called metamorphism, and the resulting rock is a metamorphic rock.

Minerals Used in Nuclear Energy

Pros & Cons

Pros:
  • Lower carbon dioxide (and other greenhouse gases) released into the atmosphere
  • Low operating costs (relatively)
  • Known, developed technology “ready” for market
  • Large power-generating capacity able to meet industrial and city needs (as opposed to low-power technologies like solar that might meet only local, residential, or office needs but cannot generate power for heavy manufacturing)
  • Existing and future nuclear waste can be reduced through waste recycling and reprocessing


Cons:

  • High construction costs due to complex radiation containment systems and procedures
  • High subsidies needed for construction and operation
  • High-known risks in an accident
  • Long construction time
  • Target for terrorism (as are all centralized power generation sources)
  • Waivers are required to limit liability of companies in the event of an accident. (This means that either no one will be responsible for physical, environmental, or health damages in the case of an accident or leakage over time from waste storage, or that the government will ultimately have to cover the cost of any damages.)
  • Uranium sources are just as finite as other fuel sources, such as coal, natural gas, etc., and are expensive to mine, refine, and transport, and produce considerable environmental waste (including greenhouse gasses) during all of these processes
  • The majority of known uranium around the world lies under land controlled by tribes or indigenous peoples who don’t support it being mined from the earth.
  • Waste lasts 200 – 500 thousand years.

If nuclear energy is not produced in a controlled manner, leaking of radioactive gasses and other harmful chemicals can cause health issues to humans (diarrhea, skin peels, central nervous system becomes severely damaged, death, cancers, leukemia). Also if not controlled properly the waste from the plant can lead to environmental damages if not properly disposed of.

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What Happened?!?

Chernobyl: On April 26, 1986, a major accident occurred at Unit 4 of the nuclear power station at Chernobyl, Ukraine. The operating crew was running a maintenance test to check the reactor for safety precautions. To prevent any interruptions to the power of the reactor, the safety systems were deliberately switched off. To conduct the test, the reactor had to be powered down to 25 percent of its capacity. This procedure did not go according to plan and the reactor power level fell to less than 1 percent. The reactor's fuel elements ruptured and there was a violent explosion. The 1000-tonne sealing cap on the reactor building was blown off. At temperatures of over 2000°C, the fuel rods melted. The graphite covering of the reactor then ignited. The graphite burned for nine days, churning huge quantities of radiation into the environment.


3-Mile Island: On March 28, 1979, the plant experienced a failure in the secondary, non-nuclear section of the plant (one of two reactors on the site). Either a mechanical or electrical failure prevented the main feedwater pumps from sending water to the steam generators that remove heat from the reactor core. This caused the plant's turbine-generator and then the reactor itself to automatically shut down. Immediately, the pressure in the primary system (the nuclear portion of the plant) began to increase. In order to control that pressure, the pilot-operated relief valve; the valve should have closed when the pressure fell to proper levels, but it became stuck open. As coolant flowed from the primary system through the valve, other instruments available to reactor operators provided inadequate information.. As alarms rang and warning lights flashed, the operators did not realize that the plant was experiencing a loss-of-coolant accident. They took a series of actions that made conditions worse. These actions starved the reactor core of coolant, causing it to overheat. Without the proper water flow, the nuclear fuel overheated to the point at which the zirconium cladding ruptured and the fuel pellets began to melt. It was later found that about half of the core melted during the early stages of the accident. Although TMI-2 suffered a severe core meltdown, the most dangerous kind of nuclear power accident, consequences outside the plant were minimal. Unlike the Chernobyl and Fukushima accidents, TMI-2's containment building remained intact and held almost all of the accident's radioactive material.