Radiation

Ionising Radiation

Ionising Radiation

Alpha Radiation

Beta Radiation

Gamma Rays

X-Rays

Neutrons

Alpha Radiation

Very short range

Stooped by air, paper or skin

Not a hazard outside the body

A concern when inside the body – cause intense local ionisation and biological damage

Beta Radiation

Longer range than Alpha

Low energy beta radiation does not penetrate the skin, whereas high energy beta can penetrate soft tissue to a depth of over one cm.

Beta inside the body is a concern, but less intense than alpha

Gamma & X-RaysBoth electromagnetic radiationGamma radiation is emitted continuously by radioactive decayX-rays are generated in special electrical equipment by bombarding a target with electronsConsequently, an x-ray beam only exists when machine is on, whereas gamma rays are emitted continuouslyPenetrating power of electromagnetic radiation depends on its energy and the properties of the matter through which it passesX-rays are able to pass through the human body, but gamma and x-rays can be stopped by lead shielding

Neutrons

Emitted during certain nuclear processes such as nuclear fission

Great penetrating power

Produce ionisation directly and can cause great harm as they pass through the body

Ionising Radiation Health Effects

Nausea and vomiting

Reduction in bodies defences

Reddening of skin

Loss of weight & hair

Blistering and ulceration of skin

Cataracts

Cancer

Genetic defects (affects subsequent generations)

MeasurementIonising radiation is measured in sieverts (Sv)Sv include a weighting factor to take into account differing biological effects of alpha, beta, gamma and neutron radiationExposure is controlled by dose limitation, which is based on the premise that for conditions having no safe threshold, exposure is reduced to a level where probability of harm is small

Detection

Film badges (personal)

Ionisation chamber (similar to geiger counter)

Personal air samplers

Analysis of faecal and urine samples

ProtectionBased on 3 principles:ShieldingDistanceReduced time exposure

Shielding is best method as it reduces risk positively. Distance and reduced time exposure are administrative controls which require considerable supervisory control

Shielding

Use of a dense medium to intercept radiation e.g. lead

Particulate radiation can be completely stopped

Electromagnetic radiation can be sufficiently absorbed so that emergent radiation has a reduced risk level

Distance Protection

The intensity of all radiation is reduced by distance travelled

Reduction is inversely proportional to the square of the distance

Reduced Time Exposure

Reduces exposure time and therefore reduces the accumulated dose

Workplace Examples of Ionising Radiation

Hospital x-ray equipment

Gamma rays are used for non-destructive testing of welds

Nuclear power generation

Non-Ionising Radiation

Non-Ionising Radiation

Does not have sufficient energy to cause ionisation in matter and can be classified into:Ultra Violet Infra RedMicrowavesRadio wavesLasers

Ultraviolet RadiationProduced by electric discharge tubes, electric arc welding and the sun

Can produce reddening, ageing or cancer of the skin

Can produce arc eye which causes pain and an aversion to bright light

Controls: Protection for face and eyes Screens Non-reflective surfaces Interlocks

Infra-Red Radiation

Produced by hot bodies

Can cause reddening of skin, burns and cataracts

Controls:DistanceEye protectionReflective clothing

Microwave Radiation

Harm is caused by heating

Can cause burns

Controls:Enclosure in metal structure with

interlocked access doors

Radio Waves

Used for heating purposes

Severe burns can occur by contact

Lasers

Can destroy tissueReflected laser radiation is as hazardous as direct raysClassed from Class 1 (safest) to 2, 3a, 3b and 4 (most harmful)Controls:Fixed shieldingEye protection

Workplace Examples of Non-Ionising Radiation

Electric arc welding (UV)

High temperatures and hot surfaces in a furnace (Infra-red)

Telecommunication (microwaves)

Heating units for particular industrial purposes (Radio waves)

Precision cutting (Lasers)