Nuclear Physics

Question 1

What is a radioisotope?

Answer 1

An unstable isotope. It may spontaneously decay by emitting a particle from the nucleus.

Question 2

What is an alpha particle?

Answer 2

An alpha particle consists of 2 protons and 2 neutrons. It is identical to a helium nucleus.

Question 3

What is a beta particle?

Answer 3

An electron that has been emitted from the nucleus of a radioactive atom.

Question 4

What is a gamma ray?

Answer 4

It is high-energy electromagnetic radiation that is emitted from the nuclei of radioactive atoms. They usually accompany alpha or beta emmission.

Question 5

At what speed at alpha particle ejected?

Answer 5

At about 10% the speed of light

Question 6

Do alpha particle have high ionisation?

Answer 6

Yes

Question 7

What is an alpha particle charge?

Answer 7

It has a double positive charge.

Question 8

What is an alpha particles penetrating ability?

Answer 8

Poor.

Question 9

What is a beta particles charge?

Answer 9

A single negative electric charge

Question 10

What is a beta particles ionising ability?

Answer 10

Moderate

Question 11

What is a beta particles penetrating ability?

Answer 11

Moderate

Question 12

What is the charge of a gamma ray?

Answer 12

They have no electrical charge

Question 13

What is a gamma rays ionising ability?

Answer 13

Weak

Question 14

What is a gamma ray’s penetrating ability?

Answer 14

High

Question 15

What is the energy of alpha, beta and gamma rays measured in?

Answer 15

Electron-volts eV

Question 16

What is a half life?

Answer 16

The time it take for half of the nuclei in a sample of radioisotopes to decay.

Question 17

What is the activity of a sample?

Answer 17

The activity of a sample indicates the number of radioactive decays that are occuring in the sample each second. Activity is measured in becquerels Bq. 1 Bq = 1 disintergration per second.

Question 18

How will the activity of a sample behave over time?

Answer 18

It will decrease over time. Over one half life the activity of a sample will halve.

Question 19

What is nuclear fission?

Answer 19

It is when a necleus is caused to split and release a nuber of neutrons. This can happen when a fissile nucleus has been struck by a neutron.

Question 20

What are the most common nuclear fuels?

Answer 20

Uranium-235 and plutonium-239

Question 21

What happens mass of the fission fragments compared to the nass of the original particles?

Answer 21

They have less mass. The decrease in mass is equivalent to the energy that is released during each fission and can be determined by E=?mc2

Question 22

What is an isotope

Answer 22

An isotope of an element has the same number of protons but a different number of neutrons

Question 23

Uranium-235 is readily fissile when…

Answer 23

It is struck by a slow neutron

Question 24

Plutonium-239 is readily fissile when…

Answer 24

Struck by a fast moving neutron.

Question 25

What may happen when a fission reaction is taking place that releases one neutron per fission?

Answer 25

A chain reaction may be established.

Question 26

What is critical mass?

Answer 26

It is the least amount of material that will sustain a chain reaction. The critical mass of a material depends on its concentration, shape and size.

Question 27

What does a nuclear reactor use as its fuel?

Answer 27

Enriched uranium fuel rods that have been enriched to 3-4% uranium-235.

Question 28

What is a moderator?

Answer 28

A material in the core of the reactor, like water or graphite, that acts to slow the neutrons that are emitted during fission.

Question 29

What are control rods and what do they do?

Answer 29

They are a material. like cadmium or boron steel, that absorb neutrons. They are raised and lowered to control the cahin reaction and produce a steady release of energy.

Question 30

What is coolant?

Answer 30

It is a liguid that flows through the reactor core and extracts heat energy from it. This energy is used to priduce steam to power turbines to produce energy.

Question 31

What does a fast breeder reactor use as its fuel?

Answer 31

Plutonium-239

Question 32

Does a fast breeder reactor need a moderator?

Answer 32

No

Question 33

Why is uranium-238 used in the core of a fast breeder reactor?

Answer 33

It absorbs neutrons and transmutes into plutonium-239, which is used as fuel.

Question 34

What is nuclear fussion?

Answer 34

The joining of two smal nuclei under conditions of high energy to produce one larger nucleus.