Nuclear Energy Flashcards
Fission
A nuclear reaction in which a neutron strikes the nucleus of an unstable atom and splits into two or more parts
Energy is released in the form of heat
- When more neutrons are released, they break apart more nuclei in a chain reaction
Radioactivity
Refers to the energy given off by the nucleus of a radioactive isotope
- Radioactive Half-Life = the amount of time it takes for 50% of a radioactive substance to decay (breakdown)
Half Life Formula
Fraction remaining = 1/2^n
Amount remaining = Original Amount x 1/2^n
n = number of half-lives elapsed
Generating Electricity
Uranium fission is used to heat water into steam (nuclear is considered nonrenewable because of fuel needed)
U-235 stored in fuel rods, submerged in water in reaction core; heat from fission turns H2O –> Steam [CONTROLLED REACTION]
Control Rods
Lowered into reactor core to absorb neutrons and slow down the reaction, preventing meltdown (explosion)
Water Pump
Brings in cool water to be turned into steam and also cools reactor down from overheating
Cooling Tower
Allows steam from turbine to condense back into liquid and cool down before being reused (this gives off H2O vapor)
Light Water Reactor
Type of reactor used most in the world (85% worldwide, 100% in U.S.)
Inefficient, losing about 83% of the energy in their nuclear fuel as waste heat to the environment
Thermal Pollution
Waste heat
- caused by nuclear reactors
Big Reserves of Nuclear Energy
Kazakhstan, Canada, Australia, Niger, Namibia
Big Users of Nuclear Energy
US, France, China, Russia, South Korea
Why is nuclear energy nonrenewable?
Nuclear energy is NONRENEWABLE because radioactive elements like Uranium are limited
Nuclear Energy Pros
- No air pollutants released when electricity is generated (mining and construction still release GHGs)
- Carbon free source of electricity
- In countries with limited fossil fuels, you can achieve independence from oil
Nuclear Energy Cons
- Generates radioactive waste
- Releases thermal pollution
- Many steps
- Expensive
- Accidents are HORRIBLE
- Uranium is not indefinite
- Spent fuel rods: used fuel rods remain radioactive for millions of years
- Mine tailings: leftover rock and soil
- Water use: deplete local surface
Effects of Radiation
Radiation is so harmful, it can cause DNA damage and mutation
- Cancer
- Brain Damage
- Eye Damage/Cataract
- GI Damage
- Damage and Birth Defects to Fetuses
- Burns
- Damage to bone marrow
- Impairment of the immune system
Radioactive Meltdown
At high temperatures the metal encasing the uranium fuel can melt
- Probability is low
Examples:
- Three Mile Island, PA
- Chernobyl, Ukraine
- Fukushima Daiichi, Japan
Plants are licensed to operate for 40 years (can be extended 20 years)
Contaminated Soil
Radiation can remain in soil and harm plants and animals in the future
Radiation Spread
Radiation can be carried by the wind over long distances; affecting ecosystems far from the meltdown site
Radioactive Waste Impacts
- Must be stored in specialized, highly secure locations because it continues to emit radioactivity
- Currently, nuclear facility are required to store their spent fuel rods (usually done in pools of water)
Storing Nuclear Waste
Any long term storage site needs to be very geologically stable, and sites are evaluated for the following:
- Volcanic Activity
- Earthquake Activity
- Characterization of Groundwater Flow
- Depth of at least 2,000 ft underground
- Away from major cities/population centers
Most scientists and engineers agree that deep burial is the safest and cheapest way to store high-nuclear waste
All High-level nuclear waste must be stored for a minimum of how many years before it decays to stable radioactive levels?
10,000 to 240,000
