The dangers of radioactivity

Question 1

Ionising radiation consisting of:

Answer 1

• alpha, beta and gamma radiation
• X-rays
• protons and neutrons

Question 2

Ionising radiation can:

Answer 2

• Damage vital molecules by creating free radical ions.
• killing living cells
• affect normal cell division,
• damage nuclei and DNA
• possibly causing cells to divide uncontrollably
• causing cancerous tumours
• in sex cells can cause mutations in succeeding generation

Question 3

Gamma radiation

Answer 3

• Most dangerous as very penetrating and can reach internal organs of body
• May kill cells but not very ionising so tends not to cause cancer when used e.g. as a tracer

Question 4

Beta radiation

Answer 4

• Absorbed but does not penetrate as far as the organs
• Hazardous as ionising

Question 5

Alpha radiation

Answer 5

Absorbed by dead skin but can cause burning if absorbed

Absorbed by living tissue as no protective skin internally and very ionising can cause cancer / damage cells/ DNA / kill cells and reach vital organs

Question 6

A film badge consists of:

Answer 6

• A strip of photographic film
• In a light proof wrapper
• Different areas of the film are covered with different absorbers and thicknesses.
  *

Question 7

​When the film is developed:

Answer 7

• Exposure to each form of radiation can be estimated as film is blackened
• If the worker has received too much radiation they can no longer work in that environment.

Question 8

What is a dose equivalent?

Answer 8

A comparative measure of the effect of each type of ionising radiation, defined as the energy that would need to be absorbed per unit mass of matter from 250 k of X-radiation to have the same effect as a certain ‘dose’ of the ionising radiation. The unit of dose equivalent is the sievert (Sv).

Question 9

An average dose for a worker =

Answer 9

2 mSv per year, although the limit is 15 mSv per year.

Question 10

Storage of radioactive materials:

Answer 10

• Should be in a lead lined containers.
• Most sources produce alpha beta and gamma sources.
• The lead lining needs to be enough to reduce the gamma from the source to the background amount.

Question 11

When using radioactive materials:

Answer 11

• Solid sources handled with long-handled tongs.
  
  • Ensures material is as far as practically possible so the intensity of the gamma is as low as possible and out of the range of alpha and beta.
• Liquid and gas sources in powdered form should be in sealed containers.
  
  • So source cannot be drunk or splashed.
• Sources should be not be used longer than usual.
  
  • To reduces exposure to ionising radiation.

Question 12

What is background radiation?

Answer 12

Radiation due to naturally occurring radioactive substances in the environment.

Question 13

Sources of background radiation:

Answer 13

• Radon gas
• Cosmic rays
• Ground/rocks/buildings
• Air
• Nuclear power stations and discharge/waste from them
• Nuclear weapons
• Air travel
• Medical waste