Ionising Radiation

Question 1

Types of ionising radiation

Answer 1

alpha, beta, gamma, neutron

Question 2

Alpha radiation

Answer 2

particles, easily absorbed by clothing and outer layers of skin, travel short distances, safe outside of the body, dangerous if ingested

Question 3

Beta radiation

Answer 3

high-energy, high-speed electron or positron emitted by the radioactive decay of an atomic of an atomic nucleus. beta has medium penetrating power and medium ionising power

Question 4

Gamma radiation

Answer 4

gamma radiation is high energy electromagnetic waves emitted from unstable nuclei; high penetrating power, gamma rays produce the least ionisation.

Question 5

Neutron radiation

Answer 5

a free neutron, usually emitted as a result induced nuclear fission. Can travel hundreds/thousands of metres in air, they are stopped by concrete or water. They are absorbed into a stable atom, thereby making it unstable and more likely to emit ionizing radiation of another type. Neutrons are the only type of radiation that are able to turn other materials radioactive (activate them).

Question 6

Activation products

Answer 6

Atomic nuclei that become radioactive because they have absorbed neutrons that change them into less stable nuclei that emit ionising radiation.

Question 7

Uses of ionising radiation

Answer 7

Energy production, X Rays and CT scans, cancer treatment, sterilisation

Question 8

Ionizing radiation average annual dose

Answer 8

The per capita radiation dose in a particular area. UK average annual radiation dose 2.7 mSv

Question 9

What affects your annual radiation dose?

Answer 9

Where you live (e.g. granite bedrock), your job (e.g. airline pilot), your diet (contaminated food), your medical needs (e.g. cancer treatment), atomic weapons fallout.

Question 10

Contamination

Answer 10

Pollution caused by the pollutant staying in contact or mixing with materials such as soil, atmosphere, water or living organisms.

Question 11

Exposure

Answer 11

In ionising radiation control, this refers to an object or person receiving radiation, but not necessarily coming in contact with the source.

Question 12

Sources of ionising radiation exposure

Answer 12

Cosmic radiation, gamma radiation for the lithosphere, radon gas emissions from the ground, Ingestion of contaminated food and water, medical exposure, occupational exposure, atomic weapons fallout, industrial discharges, consumer products (eg smoke detectors)

Question 13

Half life

Answer 13

The time taken for half of the unstable parent atom to decay to a more stable daughter atom. Half life determines persistence.

Question 14

Acute

Answer 14

Exposure to a substance or symptoms that appear rapidly.

Question 15

Chronic

Answer 15

Exposure to a substance or symptoms that appear over long periods of time.

Question 16

How much of the unstable parent isotope will remain after three half lives?

Answer 16

⅛ or 12.5%

Question 17

Effects of ionising radiation

Answer 17

Damage to cell nucleus, DNA mutation, Damage to other parts of the cell, radiation sickness, death, cancer

Question 18

Control of exposure to ionising radiation

Answer 18

Closed sources, materials to absorb radiation, protective clothing, distance from the source, reducing the period of exposure, decontamination

Question 19

Closed sources

Answer 19

enclosing the radioactive source in a container, remote handling techniques used or workers in a sealed suit with separate air source.

Question 20

Materials to absorb radiation

Answer 20

Barriers between the radioactive source and workers. Thickness and composition of material depends on the type of radiation.

Question 21

Protective clothing

Answer 21

includes lightweight suits to protect against contaminated radioactive particulate matter.

Question 22

Distance from the source

Answer 22

Increasing distance from the radioactive source reduces exposure.

Question 23

Inverse square law

Answer 23

as distance from the radioactive source is increased, there is a more than proportional decrease in exposure, e.g. doubling the distance reduces exposure by three quarters. Dose received = 1/distance squared

Question 24

Reducing the period of exposure

Answer 24

minimising the time workers are exposed to the radioactive source reduces exposure

Question 25

Decontamination

Answer 25

washing, scrubbing and exfoliating scrubs remove contamination. Potassium iodide tablets prevents uptake of radioactive iodine

Question 26

Low level nuclear waste

Answer 26

General equipment and clothing

Question 27

Managing Low level nuclear waste

Answer 27

Thick polythene bags in steel drums, inside steel truck containers inside a concrete lined landfill site (LLWR, Low-level nuclear waste repository, at Drigg near Sellafield)

Question 28

Intermediate level nuclear waste

Answer 28

Metal tubes surrounding fuel rods, filters from waste reprocessing

Question 29

Managing Intermediate level nuclear waste

Answer 29

Mixed with cement and stored in stainless steel drums - currently stored at Sellafield

Question 30

High level nuclear waste

Answer 30

Used uranium fuel rods

Question 31

Managing High level nuclear waste

Answer 31

Vitrification, powdered waste is mixed with molten glass and poured into stainless steel containers, surrounded by concrete and cooled, stored at Sellafield

Question 32

Encapsulation

Answer 32

a method of dealing with hazardous waste whereby the material is mixed with concrete and poured into a container so that the waste is immobilised.

Question 33

Vitrification

Answer 33

a specialised encapsulation technique used for high level radioactive waste, powdered radioactive waste is mixed with molten glass and poured into stainless steel containers, the containers are placed in cylindrical passage in concrete which are ventilated. Even if the glass is shattered the powdered waste will remain encapsulated in glass

Question 34

Monitoring workers exposure to ionising radiation

Answer 34

photographic film badges, dosimeters, air monitors, contamination monitors for workers leaving premises.

Question 35

Dosimeter

Answer 35

a device that measures dose uptake of external ionizing radiation. It is worn by the person being monitored and is a record of the radiation dose received. Can give a continuous readout of cumulative dose and current dose rate, and can warn the wearer with an audible alarm when a specified dose rate or a cumulative dose is exceeded

Question 36

Monitoring the environment for ionising radiation

Answer 36

Monitoring atmospheric dust, soil, water, meat fish and vegetables produced in the area.

Question 37

Critical group monitoring (CGM)

Answer 37

A method of monitoring pollutants, particularly radioactive discharges. If the members of the public that are most at risk are safe, then so is everyone else.

Question 38

Critical pathway analysis (CPA)

Answer 38

The prediction of the routes that an effluent will take in the environment, and where it may be deposited or become concentrated to assess pollution risk.

Question 39

Grays

Answer 39

A measure of absorbed dose

Question 40

Becquerel (Bq)

Answer 40

The Becquerel is the unit of activity of a radioactive source.

Question 41

Sievert

Answer 41

A measure of absorbed dose taking into account the effects of different types of radiation (relative biological effectiveness)

Question 42

Relative biological effectiveness (RBE)

Answer 42

This is a measure based on the amount of energy absorbed from ionising radiation which takes into account the damaging effects of the type of radiation.

Question 43

ALARA - As low as reasonably achievable

Answer 43

An approach to control of pollution, especially ionising radiation, where levels are kept as low as is practically achievable, taking into account economic and technological factors.

Question 44

BATNEEC - Best available technology not entailing excessive cost

Answer 44

An approach to pollution control where control technology is used that achieves the lowest emission levels, without costing so much that further marginal gains would risk their financial viability.