Atomic Structure

Question 1

Activity

Answer 1

the number of unstable atoms that decay per second in a radioactive source

Question 2

Bacquerei

Answer 2

the unit used to measure activity in radioactive substances

Question 3

Alpha

Answer 3

the same as a helium nucleus, with two neutrons and two protons, very high ionising ability but stopped by a sheet of paper, very slow but has positive charge

Question 4

Atom

Answer 4

has a nucleus of approximately 1x10^-1, has a positively charged nucleus surrounded by negatively charged electrons

Question 5

Background Radiation

Answer 5

a type of radiation that is always present around us but in very low doses (e.g. 0.1-0.2 microsieverts), which is safe. Sources include:
* Underground rocks
* Food
* Drink
* Cosmic rays from space
* Medical uses (artificial source)
* Industrial uses (artificial source)
* The ground
* Buildings
* Nuclear power (artificial source)
* Nuclear weapons test (artificial source)

Question 6

Radioactive Tracers

Answer 6

used to race the flow of a substance through an organ. The tracer contains a radioactive isotope that omits gamma radiation as it can be detected outside of the system. For example, doctors can use radioactive tracers to see if a patient’s kidney is blocked.

Question 7

Radioactive Implants

Answer 7

radioactive implants are used to destroy cancer cells in some tumours. Beta or gamma emitting isotopes are used in the form of small seeds or rods. Permanent implants use isotopes with implants long enough to eradicate the tumour over a given time, but short enough so that most of the unstable nuclei will have decayed soon afterwards.

Question 8

Gamma Knives

Answer 8

gamma knives are used to treat cancer. They work by targeting small doses at the tumour from a moveable box. Small doses pass through the healthy brain while the doses are all concentrated on the tumour. This irradiates the person.

Question 9

Barium Meal

Answer 9

used to track movement through organs, as barium shows up on x-rays

Question 10

Beta

Answer 10

the same as a high-energy electron, with medium ionising ability, stopped by 5mm aluminum, negative charge, fast

Question 11

Energy Levels

Answer 11

electrons are arranged at different distances from the nucleus in energy levels which are sometimes called shells. The electron arrangement may change when electromagnetic radiation is absorbed, causing electrons to move further from the nucleus to a higher energy level. If electromagnetic radiation is omitted, electrons move closer to the nucleus to a lower energy level.

Question 12

Fission

Answer 12

The splitting of an atom’s nucleus into two smaller nuclei and the release of two or three neutrons and energy. The energy comes from fission neutrons and fragment nuclei.

Question 13

Chain Reaction

Answer 13

occurs in a nuclear reactor when each fission events causes further fission events. On average, in a nuclear reactor, one fission event goes on to cause one more fission event. This makes sure energy is released at a steady rate. Chain reactions are kept under control using control rods.

Question 14

Fissionable Isotopes

Answer 14

the fuel in nuclear reactors, such as U-238 (as opposed to non-fissionable U-235) and Pu-239. Different elements need different reactors.

Question 15

Food Irradiation

Answer 15

the application of ionising radiation to food to extend shelf life and improve safety by killing bacteria

Question 16

Nuclear Reactor

Answer 16

used to generate nuclear power

Question 17

Control Rods

Answer 17

are evenly spread and are used to control the amount of reactions. These absorb surplus neutrons and can be adjusted to maintain steady chain reactions.

Question 18

Generator

Answer 18

generates heat which creates steam

Question 19

Heat Exchanger

Answer 19

where the water from the turbines is turned to steam to power them

Question 20

Pump

Answer 20

supplies water to maintain the volume when the primary reactor coolant has contracted due to decreased load

Question 21

Turbines

Answer 21

these create the energy as they are driven by steam that is produced in the heat exchanger of the reactor. The energy used to heat the water comes from the nuclear generator.

Question 22

Reactor Core

Answer 22

is made of thick steel to withstand the very high pressure and temperature in the core. This is where the reactions happen.

Question 23

Fuel Rods

Answer 23

must be made of fissionable isotopes, often U-235 or Pu-239. These must be disposed of safely (often by burial) after they have been used as they are still radioactive

Question 24

Pressuriser

Answer 24

increases pressure

Question 25

Steel Vessels

Answer 25

are made of steel to withstand the high temperatures and to enclose the radiation. They enclose the heat exchanger and the reactor core

Question 26

Concrete Sheild

Answer 26

both vessels are enclosed by thick concrete walls. These absorb ionising radiation that escapes through the walls of the steel vessel.

Question 27

Fusion

Answer 27

happens in the Sun and other stars. During fission, small nuclei join together to form a larger nuclei and energy is released. Particles must be under huge pressure to create fusion. Temperatures of 15million degrees Celsius may be needed. The hydrogen fuse to form helium nuclei, releasing vast amounts of energy. However, it is difficult to force protons together because of their repulsive electrostatic forces, so it only occurs at very high pressures and temperatures. These are the conditions where it occurs in starts but it is very hard to replicate those conditions on earth.

Question 28

Gamma

Answer 28

electromagnetic wave, least ionising, stopped by thick concrete, no charge, travels at the speed of light

Question 29

Geiger Counter

Answer 29

used to measure the amount of radioactivity in the air

Question 30

Half Life

Answer 30

the time taken for half of the radioisotopes in a substance to decay, or for the count rate to halve

Question 31

Induced Nuclear Fission

Answer 31

occurs when a stable isotope is struck by a neutron. The isotope absorbs the neutron, becomes unstable and then splits into two smaller fragments, releasing neutrons and energy. Induced fission is under control and deliberate.

Question 32

Ionisation

Answer 32

any process by which atoms become charged

Question 33

Irradiation

Answer 33

when an object is exposed to ionising radiation but does not become radioactive. It happens when there is radioactive material outside your body that can reach you as waves. X-rays are a form of irradiation. A person is unlikely to develop cancer through irradiation.

Question 34

Isotope

Answer 34

has the same number of protons, but a different number of neutrons

Question 35

Net Decline

Answer 35

the overall amount that the activity of a source has fallen in a period of time.

Question 36

Neutrino

Answer 36

a particle able to travel faster than the speed of light

Question 37

Nuclear Bombs

Answer 37

unctrolled fission reactions

Question 38

Nucleus

Answer 38

made out of protons and neutrons and is positively charged and makes up most of the mass of the atom

Question 39

Particle Physicist

Answer 39

someone who studies the part of physics relating to particles

Question 40

Radioactive

Answer 40

substances that emit nuclear radiation

Question 41

Radiation

Answer 41

the word for alpha and beta particles and gamma rays that are being emitted from a substance

Question 42

Radiation Dose

Answer 42

a measure of the risk of harm resulting from an exposure of the body to the radiation depends on the type of radiation used, how long the body is exposed to it and the energy per second absorbed by the body from the radiation

Question 43

Speed of light

Answer 43

3x10^8

Question 44

Spontaneous Fission

Answer 44

is roughly the same as induced fission, as it releases neutrons and energy. Occurs without a neutron being absorbed

Question 45

Unstable

Answer 45

an element becomes unstable if it has too many protons or neutrons. In an attempt to stabilise itself, it omits radioactivity, decaying