““The World We Create”The World We Create”NATS 101NATS 101Section 6Section 6

New Homework Posted in D2L.

Due on Tuesday at 2 PM.

01/28

UNIT 1: Energy Sources,

Conventional or Alternative?

Nuclear Energy

Why do some countries use more nuclear energy than others?

Central Questions

What is the difference between producing chemical energy and nuclear energy?

What do we mean by ionizing radiation?

How can we detect the presence of ionizing radiation in our surroundings?

Limited SourcesThe earth’s reserves of fossil fuels are limited:

2007 2020 2030 2040 2050 2300

Gas begins to run out

Oil begins to run out

Coal begins to run out

Because of this we need to: Conserve; Improve efficiency; Develop new chemical fuels; Search for alternative sources of energy.

United States vs. France ELECTRICITY PRODUCTION

US FRANCE

Country # Nuclear Power Plants

% Electricity from Nuclear Power

U.S. >100 21

France 56 75Japan 40 26

UK 37 20Sweden 12 46

Nuclear Energy Output Different Countries

Different Choices

What factors may have influenced these countries’ choices?

(political, economical, social, environmental, historical, etc.)

Are you for or against the use of Nuclear Energy?

Why?

You have 3-4 minutes

Why are we afraid of Nuclear Energy?

Two different types of processes:

Chemical Reactions Nuclear Reactions

Atoms only rearranged Mass is not “lost” Energy is produced

C(s) + O2(g) CO2(g)235

92U + 10n

14156Ba + 92

36Kr + 3 10n

New atoms form Mass is “lost” Vast amounts of energy is produced

Atomic Structure

Atoms of the same element have the number of protons in the nucleus (Atomic Number)

Atoms of the same element that differ in the number of

neutrons are called ISOTOPES

(they have different mass number)

(Number of protons)

(Number of protons plus neutrons)

Nuclear Fission

23592U + 1

0n 14156Ba + 92

36Kr + 3 n10 + energy

A small amount of mass is transformed into a huge amount of energy. E = mc2

We have developed strategies to split atomic

nuclei apart (fission).

Neutron bombardment

Some mass is lost in the process!

Let’s Calculate

If you induce the fission of 1.0 g of Uraniumyou get 90,000,000,000,000 = 9.0 x 1013 J

During the nuclear fission of Uranium, 0.1% of the mass is transformed into energy.

E = mc2 C= 300,000,000 m/s

Equivalent to the energy

Released by 33,000 tons of TNT

Needed to raise 700,000 cars 6 miles into the sky

Turn 8.7 million gallons of water into steam

Radiation

Most of the energy generated during a nuclear process is released in the form of RADIATION.

Radiation is energy in the form of waves or particles sent out over a distance.

Microwave radiation

Ultraviolet light

X-rays

Infrared radiation

Visible light

Matter InteractionsDifferent types of radiation interact differently

with matter.

You have 8 minutes

Make a drawing that models what you think happens when each type of radiation interacts with molecules

or atoms in your body.

Microwave radiation

Ultraviolet light

X-raysInfrared radiation

Visible light

Non-Ionizing Radiation:

Low energy levels: Strong enough to influence the atoms or molecules it contacts

(translation, rotation, vibration), but not strong enough to affect their structure.

Ionizing Radiation:

Higher energy levels: It has enough energy to affect the structure of the

atoms. Particularly, to remove electrons (ionize).

Radiation

Radiation

Radioactivity

Some substances, such as uranium and plutonium, emit ionizing radiation spontaneously

(you don’t need to split them).

This property is called Radioactivity

Radioactivity results from changes in the atomic nuclei of the

atoms

How do we detect and measure it?

Geiger CounterThe Geiger Counter measures the number of ionizing events

per unit of time (counts per minute or CPM).

(+)

How would you design/build an instrument like

this?

Radioactive StuffLet’s measure the radioactivity of several objects

and substances using a “Geiger Counter.”

Why are they radioactive?