Ionising Radiation

1. Ionising Radiation

2. Particulate:

Alpha Radiation

Beta Radiation

Non-Particulate:

Gamma Rays

 X-Rays
 Neutrons

3. 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

4. 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

5. 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

6. 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

7. Industrial Radiography (e.g. for NDT)

Medical, dental and veterinary x-ray

equipment
Nuclear power generation


8. 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

9. 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)

10. 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


11. Film badges (personal)

Ionisation chamber

Geiger counter

Personal air samplers

Analysis of faecal and urine samples


12. 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

13. Shielding

Containment

Ventilation

Glove boxes or fume hoods

Under negative pressure


14. 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


15. PPE

Gloves, overalls, eye protection, RPE etc.

Local Rules:

Hazard assessment

 Contingency plans
 Radiation protection advisor
 Monitoring procedures etc. etc.

16. 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

17. 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

18. 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.