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FIND OUT MORE. Atoms 157 • Energy 166 • Energy Resources 60–61

WHY IS RADIOACTIVITY DANGEROUS?

To a living cell an alpha particle, beta particle, or

a gamma ray is like a bullet from a gun. Its energy

damages molecules, disrupting the cell’s life processes.

Long-term exposure to radiation can cause cancers,

such as leukaemia. Exposure to a single, large dose of

radiation can produce radiation sickness and death.

Radioactive material must be handled with great care.

The energy that makes the stars shine and produces

the heat inside a nuclear reactor is nuclear energy.

It is produced by the strong force that holds protons

and neutrons together inside atomic nuclei.

HOW IS RADIOACTIVITY USEFUL?

Radioactive substances decay over time in a

predictable way. Geologists and archaeologists can

date rocks by measuring the radiation they emit. In

industry, radiation is used to trace underground pipes

and to kill dangerous germs on food before it is

packaged. In medicine, radiation treats cancer and

sterilizes medical instruments.

HOW IS A NUCLEAR REACTION CONTROLLED?

The fission of. RADIOACTIVE uranium produces

nuclear energy. The process is controlled by

adjusting the number of neutrons produced. Control

rods that absorb neutrons are inserted between the

uranium fuel rods. They are raised or lowered to

maintain a steady release of energy.

WHAT ARE FUSION AND FISSION?

Two kinds of reaction release nuclear energy. Fusion

takes place when two light nuclei combine (fuse)

to make a heavier nucleus. This is the process that

powers the stars. Fission takes place when an unstable

nucleus of a heavy element, such as uranium, splits

in two. Fission is used in nuclear power stations.

Strong forces act inside the nuclei of

atoms. Some atoms are unstable – they

decay (break down) over time, releasing

energy as radiation. These atoms are

radioactive. There are three main types of

radiation – alpha, beta, and gamma.

4 NUCLEAR WASTE

A nuclear technician checks

nuclear waste storage containers

for emissions of radiation. The

radiation detector records the

number of radioactive particles

(alpha, beta, and gamma rays)

penetrating the thick walls of

the storage containers.

Nuclear Energy

NUCLEAR FUEL 1

Rods of nuclear fuel generate

heat in a nuclear reactor. The

used fuel rods are still hot and

highly radioactive. A remotely

operated crane transfers rods

from the reactor core to a

water-filled cooling pond.

FISSION 3
A neutron triggers the fission
(splitting) of a large, unstable
nucleus, uranium-235 for
example. Energy is released
along with more neutrons,
which may trigger further
fission reactions.

FUSION 3

At the temperatures found in

the interior of stars, nuclei of

deuterium and tritium (forms

of hydrogen) fuse to form a

nucleus of helium. The fusion

reaction releases a large

amount of energy.

Crane

Water cools the fuel

rods and shields

workers from

dangerous radiation

Tritium

nucleus

Fuel rod

Nucleus of

uranium-235

Energy

released

Helium

nucleus

formed

Deuterium

nucleus

Neutron

Neutron

Neutron

Energy

released

Neutron

RADIOACTIVITY

MARIE CURIE

French,1867-1934

Polish-born physicist Marie

Curie was one of the first

scientists to investigate

radioactivity. She discovered

the radioactive element

radium. She was the first

person ever to win two Nobel

Prizes. Marie Curie died from

leukaemia caused by the

radiation she worked with.

nuclear

energy