Miss Nelson

SCIENCE ~ CHAPTER 12

ENERGY AND MATERIAL

RESOURCES

Nuclear Energy

SECTION 3

ANTICIPATORY SET

What does an atom look like?

What are the parts of an atom?

S 6.6.a-Students know the utility of energy sources is determined by factors that are involved in converting these sources to useful forms and the consequences of the conversion process

S 6.6.b-Students know the different natural energy and material resources, including air, soil, rocks, minerals, petroleum, fresh water, wildlife, and forests; and know how to classify them as renewable or nonrenewable

STANDARDS

What happens during a nuclear fission reaction?

How does a nuclear power plant produce electricity?

How does a nuclear fusion reaction occur?

THE BIG IDEA

Nucleus – the central core of an atom that contains the protons and neutrons

Nuclear fission – the splitting of an atom’s nucleus into two smaller nuclei and neutrons

Reactor vessel – the part of a nuclear reactor where nuclear fission occurs

KEY TERMS

Fuel rod –a uranium rod that undergoes fission in a nuclear reactor

Meltdown – a dangerous condition in which fuel rods inside a nuclear reactor melt

Nuclear fusion – the combining of two nuclei to produce a single larger nucleus and much energy

KEY TERMS

The center core of an atom that contains the protons and neutrons is called the nucleusMore than one nucleus = nuclei

Reactions that involve nuclei (called nuclear reactions) result in tremendous amounts of energy

NUCLEAR ENERGY

There are two types of nuclear reactions:

FissionFusion

NUCLEAR ENERGY

Nuclear reactions convert matter into energy

NUCLEAR FISSION

What matter is changed into energy, and enormous amount of energy is released

Albert Einstein developed a formula that described the relationship between energy and matterE = mc2

E – energy M – mass C – speed of light

NUCLEAR FISSION

Nuclear fission is the splitting of an atom’s nucleus into two smaller nuclei

FISSION REACTIONS

The fuel for this reaction is a large atom that has an unstable nucleus Such as Uranium-235 (U-235)

When the neutron hits the U-235 nucleus, the nucleus splits apart into two smaller nuclei and two or more neutrons

The total mass of all these particles is a bit less than the mass of the original nucleus

The small mass that makes up the diff erence has been converted into energy A LOT of energy!

FISSION REACTIONS

While this was happening…The reaction has produced more neutrons!

If any of these strike another nucleus, the fission reaction starts over again

More neutrons, and more energy are released…

If there are enough nuclei around, the process starts a chain reaction

The amount of energy released increases dramatically with each new reaction

FISSION REACTIONS

So what happens to all this energy?

If a nuclear chain reaction IS NOT controlled…A HUGE EXPLOSION!!

Such as the explosion of an atomic bomb

If the chain reaction IS controlled…The energy is released as heat, which can be used to generate electricity (nuclear power plant)

ENERGY FROM FISSION

Read Nuclear Fission on pages 494-495 of your textbook

NUCLEAR FISSION

Controlled nuclear fission reactions take place inside nuclear power plants

Nuclear power plants generate as much of the world’s electricity

About 20 percent in the United States

About 70 percent in France

NUCLEAR POWER PLANTS

The uranium fuel for nuclear power plants is refined from uranium ores

Uranium ore is fairly abundant

Since new uranium ore is not being created, uranium is considered a nonrenewable resource

NUCLEAR FUEL

In a nuclear power plant, the heat released from fission is used to change water into steam

The steam then turns the blades of a turbine to generate electricity

ENERGY PRODUCTION

Read the specifics of Energy Production on pages 496 of your textbook

ENERGY PRODUCTION

Accidents at nuclear power plants have led to safety concerns If the fuel rods in a power plant cause too much heat

they can cause a meltdown

Another problem with nuclear power is the disposal of highly radioactive wastes

Nuclear plants also emit lots of heat to the air and nearby bodies of water However, they don’t emit carbon dioxide, so they

might not contribute to global warming

PROS AND CONS

In nuclear fusion, two hydrogen nuclei combine to create a helium nucleus, which has slightly less mass than the two hydrogen nuclei.

The lost mass is converted to large amounts of energy.

THE QUEST TO CONTROL FUSION

Nuclear fusion is the process by which the sun produces energy

On Earth, fusion is a promising future energy source Fusion fuels are readily available

However, fusion can take place only at extremely high pressure s and temperatures

The construction of a practical fusion reactor is a major engineering challenge that may take many years to complete

TO QUEST TO CONTROL FUSION

What is nuclear fission?

Describe the steps that occur in a nuclear fission reaction?

CHECK FOR UNDERSTANDING

What is nuclear fission?Nuclear fission is the splitting of an atom’s nucleus into two smaller nuclei.

Describe the steps that occur in a nuclear fission reaction?In a nuclear fission reaction, a neutron strikes a U-235 nucleus, which splits into two smaller nuclei and releases two or more neutrons and energy.

CHECK FOR UNDERSTANDING

What type of nuclear reaction produces electricity in a nuclear power plant?

What are the steps involved?

GUIDED PRACTICE

What type of nuclear reaction produces electricity in a nuclear power plant?The type of nuclear reaction that produces electricity in a nuclear power plant is a controlled nuclear fission chain reaction.

What are the steps involved?The steps involved in a controlled nuclear fission chain reaction are thermal energy is released by fission reaction and used to boil water, which produces steam to turn the blades of a turbine which generate electricity.

GUIDED PRACTICE

Complete Energy 12-3 Independent Practice

INDEPENDENT PRACTICE