Ionising Radiation

Particulate:

Alpha Radiation

Beta Radiation

Non-Particulate:

Gamma Rays

X-Rays

Neutrons

Very short range

Stopped by air, paper or skin

Not a hazard outside the body

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

Longer range than Alpha

Low energy beta radiation does not penetrate the skin, but 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

Both electromagnetic radiation

Gamma radiation is emitted continuously by radioactive decay

X-rays are generated in special electrical equipment by bombarding a target with electrons

Consequently, an x-ray beam only exists when machine is on, whereas gamma rays are emitted continuously

Penetrating power of electromagnetic radiation depends on its energy and the properties of the matter through which it passes

X-rays are able to pass through the human body, but gamma and x-rays can be stopped by lead shielding

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

Industrial Radiography (e.g. for NDT)

Medical, dental and veterinary x-ray equipment

Nuclear power generation

Ionising radiation is measured in sieverts (Sv)

Sv include a weighting factor to take into account differing biological effects of alpha, beta, gamma and neutron radiation

Exposure 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

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)

Some effects of ionising radiation are dose dependent and only occur if dose received is above certain level:

Radiation sickness, skin burns or cataracts

Other effects are not dose dependent. Any exposure to radiation may cause the effect. However, likelihood of harm increases at higher levels of exposure:

Cancer, Genetic defects

Film badges (personal)

Ionisation chamber

Geiger counter

Personal air samplers

Analysis of faecal and urine samples

Based on 3 principles: Shielding

Distance

Reduced 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

Containment

Ventilation

Glove boxes or fume hoods

Under negative pressure

Restricted access

IRR99 require designation of:

Controlled areas (dose is likely to exceed three tenths of dose limit)

Classified persons (personal exposure likely to exceed three tenths of dose limit)

Supervised areas (dose likely to exceed one tenth of dose limit)

Systems of work

Permit to work reduces time exposure

PPE

Gloves, overalls, eye protection, RPE etc.

Local Rules:

Hazard assessment

Contingency plans

Radiation protection advisor

Monitoring procedures etc. etc.

Employer must ensure that employees (18 and above), trainees (less than 18), women of reproductive capacity and other persons are not exposed to ionising radiation to an extent that exceeds annual dose limits in Schedule to Regulations

Requirement to restrict exposure sfairp includes:

Proper maintenance, examination and test of engineering controls, design features, safety features or warning devices

Provision concerning pregnant or breast feeding women

Definition:

Someone likely to receive radiation dose of more than 3/10ths of any relevant dose limit

Someone likely to receive effective dose of more than 6mSv per year

Must be over 18 years old

Certified as fit for the work by appointed doctor or Employment Medical Advisor

Someone who may enter a “controlled” area

Specific Arrangements:

Dosimeters/film badges to measure exposure

Assessment of significant doses

Use of approved dosimetry service

Provide health surveillance

Keep records of doses/health checks etc.