Radiation

Question 1

What is the nature of alpha radiation?

Answer 1

Description = 2 neutrons & 2 protons which is the same as a helium nucleus
Electric Charge = +2
Relative Atomic Mass = 4
Penetrating Power = stopped by paper or few cm’s of air
Ionising effect = Strongly ionising

Question 2

What is the nature of beta radiation?

Answer 2

Description = High energy electron 
Electric charge = -1
Relative atomic mass = 1/1860
Penetrating power = stopped by few mm of aluminium 
Ionising effect = Weakly ionising

Question 3

What is the nature of gamma radiation?

Answer 3

Description = High energy electromagnetic radiation
Electric charge = 0
Relative atomic mass = 0
Penetrating power = Stopped by few cm’s of lead and by few meters of concrete
Ionising effect = Very weakly ionising

Question 4

What is ionisation?

Answer 4

Ionisation is the addition or removal of an electron to create an ion

Question 5

What can ionisation do to a neutral atom?

Answer 5

If an atom loses an electron it becomes a positive ion ( i.e positively charged)
If an atom gains electrons it becomes a negative ion ( i.e negatively charged)

Question 6

What is the formula that shows the relationship between activity, time and number of nuclei decays ?

Answer 6

A=N/t

Question 7

What are some sources of Background radiation?

Answer 7

Cosmic rays , Radon gas , Food (bananas) , Medical (X-rays , radiotherapy , tracers etc.) , buildings , water , air

Question 8

What are some dangers of Ionising radiation to living cells?

Answer 8

Can cause damage to the cells which can cause mutations which can lead to the cells becoming cancerous

Question 9

What is the relationship between absorbed Dose , Mass and energy ?

Answer 9

D=E/m

Question 10

What is the relationship between equivalent Dose , Dose and weighting factor?

Answer 10

H=DxWr

Question 11

What is the relationship between: equivalent dose rate , equivalent dose and time?

Answer 11

H dot = H/t

Question 12

What are some natural sources of radiation?

Answer 12

Cosmic Rays , geology of the local area , latitude and altitude

Question 13

What are some artificial sources of radiation?

Answer 13

medical and dental X-Rays , radiation used in medical diagnosis and treatment ( radiotherapy) , radioactive fallout from nuclear weapons testing , radioactive waste from nuclear power stations , industrial and consumer use of radiation ( smoke detectors,UV sterilisation equipment , Industrial measurement equipment)

Question 14

What is the exposure safety limit for the public?

Answer 14

1mSv ( this is in addition to the annual background radiation in the UK)

Question 15

What is the annual background radiation in the UK?

Answer 15

2.2 mSv

Question 16

What is the annual effective dose limit for a radiation worker?

Answer 16

20mSv ( this is again in addition to the annual background radiation)

Question 17

What are some applications of Nuclear Radiation?

Answer 17

Medical = X-rays , CAT scans , treatment of certain conditions , Tracers that involve a radioactive material
Academic/Scientific = demonstrating principles to students, carbon dating and scientists experimenting with radiation to see the effects on different materials
Industrial = Smoke detectors, monitor the thickness of a material , clothe’s are irradiated so chemicals bind better, Non stick pans are irradiated so they function better , crop seeds are irradiated so they are more resistant
Energy Generation = Nuclear power plants
Military = Nuclear weapons

Question 18

Describe an experiment which may be used to measure the half-life of a material

Answer 18

Stopclock, geiger muller tube, geiger counter, clock and radioactive source

Before the source is used the background count rate is measured using a Geiger Muller tube connected to a counter. The count rate from the source is then measured at regular fixed intervals over a period of time.

The background count rate is subtracted from each measurement of the count rate and so the actual count rate from the source is calculated (known as the ‘corrected count rate’).
A graph of the count rate of the source against time is plotted.

Question 19

How would you use graphical data to determine the half life of a material?

Answer 19

Half the Initial count rate value then find that number on the graph and then find the corresponding time on the graph and that time is your ‘Half-Life’

Question 20

Give a Quality description of Fission

Answer 20

This is the process in which energy is released when a large atom is hit by a neutron, becomes unstable and splits up into 2 or more smaller pieces plus 2 or 3 neutrons.
When this happens,some of the mass of the atom is ‘Lost’ - it has been converted directly into energy. This energy is in the form of heat which can be harnessed and used to generate electricity in a Nuclear Power Station

Question 21

Give a quality description of chain reactions

Answer 21

In a Nuclear Fission reaction when the 2 or 3 neutrons are released they can hit other Uranium Nucleus’s which can cause another fission reaction.

Question 22

What does fission and chain reactions have to do with the generation of energy?

Answer 22

In a Nuclear power station, nuclear fuel undergoes a controlled chain reaction in the reactor to produce heat - nuclear energy is converted to heat energy:

heat is used to change water into steam in the boiler
the steam drives the turbine (heat to kinetic energy)
this drives the generator to produce electricity - kinetic to electrical energy

Question 23

Give a quality description of Fusion

Answer 23

Fusion is when 2 small nuclei are fused together. This only happens under extreme temperature and pressure conditions.
This is what happens in the sun
Heavy isotopes of hydrogen nuclei are fused together to form helium ( and an extra neutron).

Question 24

Give a quality description of Plasma Containment

Answer 24

Plasma containment is the act of maintaining plasma in a discrete volume . Magnetic fields must be used as plasma is ordinarily hotter than the degradation temperature of any known material

Question 25

What does fusion and plasma containment have to do with the generation of energy ?

Answer 25

A Nuclear fission reaction can only happen under extreme temperature conditions, because of these extreme temperature conditions the atoms in the reaction change state into plasma. The plasma must be stored in electromagnetic fields as its temperature is much higher than the degradation point of any known material. If this can be done safely with minimal input and maximum output this can be a safe,renewable way to source energy. Low C02 emissions , very minor radioactive contamination and no chance of a nuclear disaster similar to Chernobyl or Three mile island.