UNIT 11: NONRENEWABLE ENERGYSection 3: Nuclear Energy

BASICS OF ATOMS

● Atoms are the smallest unit of matter

● Made up of protons, neutrons, and electrons

● Isotope – Atom that has gained or lost neutrons, making it have a different mass than usual

● This can lead to the isotope being unstable

● An unstable isotope can be struck with an additional neutron, causing it to split, releasing energy

WHAT IS NUCLEAR ENERGY?

● Nuclear energy is the energy that exists within the nucleus of an atom.

● There are 2 types of Nuclear Energy:

•Nuclear fission is the splitting of a large nucleus, releasing HUGE amounts of energy.

•Nuclear fusion is the combining of smaller nuclei to form heavier nuclei, releasing HUGE amounts of energy.

HOW IS NUCLEAR FISSION ENERGY PRODUCED?

IF A NUCLEAR REACTION IS NOT CONTROLLED…

NUCLEAR ENERGY MUST BE HARNESSED IF USED TO MAKE ENERGY.

● Nuclear reactions in a nuclear power plant occur at a controlled, manageable pace and release energy slowly.

● Heat is generated and used to boil water, creating steam. The steam turns turbines which rotate electric generators, creating electricity.

● Steam is released from the cooling towers.

HOW DOES A NUCLEAR POWER PLANT WORK?

HOW MUCH ENERGY IS PRODUCED?

● Nuclear power is an extremely rich energy source.

● One gram of Uranium-235 delivers as much energy as 3.5 metric tons of coal!!!

● One in every 5 houses in the U.S. is supplied with nuclear energy.

WHERE ARE NUCLEAR POWER PLANTS LOCATED?

PROS FOR NUCLEAR POWER

● Rich energy source! Can replace TONS of Fossil Fuels

● Reactors run for years without refueling or being shut down and need little maintenance.

● No air pollution!

CONS ABOUT NUCLEAR POWER

● Produces Radioactive Waste

● There is no permanent long-term disposal site for commercial nuclear waste.

● There is a relatively short supply of 235U (only enough left for 100~200 years)

● Nuclear Power Plants are expensive to build.

● Thermal Pollution

● Risk of catastrophic meltdown

POTENTIAL FOR DISASTER!

● Chernobyl meltdown in the former Soviet Union.

● Hundreds died from radiation exposure.

● Thousands contracted cancers from high levels of radiation exposure.

A CLOSE CALL AT HOME!!!

● The most serious nuclear accident in the U.S. occurred in 1979 at Three Mile Island nuclear power plant in Pennsylvania.

● Partial meltdown of fuel rods

● A small amount of radioactive gas escaped the containment structure.

FUKUSHIMA DAIICHI

● Nuclear power plant in Japan

● Damaged during major 2011 earthquake but emergency equipment worked

● Tsunami flooded emergency equipment and caused partial meltdown and explosions

WHAT IS A HALF-LIFE?

● Every radioactive element has a half-life

● Half-life is the time it takes for half of its atoms to decay.

● Half-lives range from a fraction of a second to billions of years – 4.5 billion for uranium 238.

● The longer the half-life, the less intense the radiation.

● After 10 half-lives, an element is usually harmless

HALF-LIFE GRAPH OF NITROGEN-13

TYPES OF WASTE

•High-Level Waste•The most dangerous radioactive waste•Consists of spent nuclear material from nuclear reactors

TYPES OF WASTE

● Low-Level Waste

● Material that has been contaminated with radiation or radioactive material

● Clothing, medical waste, equipment, etc.