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Radiation

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

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Radiation

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  1. Radiation

  2. Ionising Radiation

  3. Ionising Radiation • Alpha Radiation • Beta Radiation • Gamma Rays • X-Rays • Neutrons

  4. 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

  5. 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

  6. Gamma & X-Rays • 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

  7. 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

  8. 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)

  9. Measurement • 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

  10. Detection • Film badges (personal) • Ionisation chamber (similar to geiger counter) • Personal air samplers • Analysis of faecal and urine samples

  11. Protection • 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

  12. 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

  13. Distance Protection • The intensity of all radiation is reduced by distance travelled • Reduction is inversely proportional to the square of the distance

  14. Reduced Time Exposure • Reduces exposure time and therefore reduces the accumulated dose

  15. Workplace Examples of Ionising Radiation • Hospital x-ray equipment • Gamma rays are used for non-destructive testing of welds • Nuclear power generation

  16. Non-Ionising Radiation

  17. Non-Ionising Radiation • Does not have sufficient energy to cause ionisation in matter and can be classified into: • Ultra Violet • Infra Red • Microwaves • Radio waves • Lasers

  18. Ultraviolet Radiation • Produced 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

  19. Infra-Red Radiation • Produced by hot bodies • Can cause reddening of skin, burns and cataracts • Controls: • Distance • Eye protection • Reflective clothing

  20. Microwave Radiation • Harm is caused by heating • Can cause burns • Controls: • Enclosure in metal structure with interlocked access doors

  21. Radio Waves • Used for heating purposes • Severe burns can occur by contact

  22. Lasers • Can destroy tissue • Reflected laser radiation is as hazardous as direct rays • Classed from Class 1 (safest) to 2, 3a, 3b and 4 (most harmful) • Controls: • Fixed shielding • Eye protection

  23. 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)

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