Chapter 16 – Nuclear Energy

Alternate to Fossil Fuels

16.1 Atoms and Radioactivity

All matter consists of atoms

All atoms contain:

Protons ( + charge) found in nucleus

Electrons (– charge) orbit around the nucleus

Neutrons (neutral charge) found in nucleus

16.1 Atoms and Radioactivity

Atomic number equals the number of protons and electrons in one atom of any element

Atomic Mass is the amount of stuff contained in one atom of an element

Subtract the Atomic number from the Atomic mass to get the number of neutrons

16.1 Atoms and Radioactivity

Isotope:

Atoms of the same element can have different Atomic masses.

The mass changes because nucleus has a different number of neutrons

Ex: Uranium has isotope of U235 and U238

16.1 Radioactivity Isotopes can be stable

or unstable

Unstable isotopes release energy in the form of protons or neutrons to become stable

Marie Curie – Nobel scientist, was the first person to use radioactive to describe the release of energy

16.1 Radioactivity Three kinds of energy

given off by radioactive isotopes are

Alpha particles (2 protons and 2 neutrons) changes atomic mass and number or radioactive decay

Beta particles (high speed electrons)

Gamma rays (electromagnetic radiation)

16.1 Radioactivity Half-Life

The amount of time in which half of the atoms in a sample of radioactive element.

Radioactive compounds take from days to thousands of years to lose only one-half of their total radioactive energy

16.2 Reactions and Reactors

Nuclear fission: reaction where the nucleus of a large atom breaks into smaller nuclei

The fission of U235 shows how a neutron hits the Uranium nucleus causing it to split into two smaller (daughter) nuclei and release two neutrons to hit two more Uranium atoms in a chain reaction

16.2 Nuclear ReactorsNUCELAR REACTORS

PRODUCE ELECTRICITY

• FISSION OF U235 PRODUCES HEAT

• HEAT BOILS WATER TO MAKE STEAM

• STEAM TURNS TURBINES WHICH GENERATE ELECTRICITY

Parts of a Nuclear Reactor

Fisson takes place in a REACTOR VESSEL

The U235 in packed into FUEL RODS

The rods are surrounded by WATER that COOLS and SLOWS NEUTRONS

CONTROLL RODS slow down the reaction

The heated water produces STEAM that turns the TURBINES that generate ELECTRICITY

Breeder Reactors Breeder Reactors can

PRODUCE THEIR OWN FUEL

Uses Plutonium239 core surrounded by stable Uranium238.

Uranium captures a neutron from Plutonium and becomes U239 which is unstable

This CHAIN REACTION between Plutonium and Uranium produces energy and heat

Radioactive Waste Nuclear power plants produce lots

of HIGH-LEVEL radioactive waste such as fuel and control rods, coolant (water or sodium) and the reactor vessel.

High-level waste can cause burns, severe DNA damage, radiation sickness and death

Hospitals, mining, contaminated clothing from power plants are considered MEDIUM-LOW LEVEL radioactive waste.

Low-level waste causes DNA damage, increased risk of cancer and other health problems

RADIOACTIVE Waste Disposal

HALF-LIFE of most radioactive compounds is hundreds to thousands of years.

U235 has a half-life of 4.5 BILLION years

Plutonium239 has a half-life of 24,000 years

They will be toxic for generations to come.

Bury low and medium-level wastes (Yucca Mountain –Utah)

High-level wastes are stored at the nuclear reactors