Nuclear Energy

Question 1

Fission

Answer 1

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

Question 2

Radioactivity

Answer 2

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)

Question 3

Half Life Formula

Answer 3

Fraction remaining = 1/2^n

Amount remaining = Original Amount x 1/2^n

n = number of half-lives elapsed

Question 4

Generating Electricity

Answer 4

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]

Question 5

Control Rods

Answer 5

Lowered into reactor core to absorb neutrons and slow down the reaction, preventing meltdown (explosion)

Question 6

Water Pump

Answer 6

Brings in cool water to be turned into steam and also cools reactor down from overheating

Question 7

Cooling Tower

Answer 7

Allows steam from turbine to condense back into liquid and cool down before being reused (this gives off H2O vapor)

Question 8

Light Water Reactor

Answer 8

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

Question 9

Thermal Pollution

Answer 9

Waste heat

- caused by nuclear reactors

Question 10

Big Reserves of Nuclear Energy

Answer 10

Kazakhstan, Canada, Australia, Niger, Namibia

Question 11

Big Users of Nuclear Energy

Answer 11

US, France, China, Russia, South Korea

Question 12

Why is nuclear energy nonrenewable?

Answer 12

Nuclear energy is NONRENEWABLE because radioactive elements like Uranium are limited

Question 13

Nuclear Energy Pros

Answer 13

• 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

Question 14

Nuclear Energy Cons

Answer 14

• 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

Question 15

Effects of Radiation

Answer 15

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

Question 16

Radioactive Meltdown

Answer 16

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)

Question 17

Contaminated Soil

Answer 17

Radiation can remain in soil and harm plants and animals in the future

Question 18

Radiation Spread

Answer 18

Radiation can be carried by the wind over long distances; affecting ecosystems far from the meltdown site

Question 19

Radioactive Waste Impacts

Answer 19

• 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)

Question 20

Storing Nuclear Waste

Answer 20

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

Question 21

All High-level nuclear waste must be stored for a minimum of how many years before it decays to stable radioactive levels?

Answer 21

10,000 to 240,000