Ionising and non-ionising Radiation:
Electromagnetic radiation consists of varying electric and magnetic fields, operating at right angles to each other. It has both particulate and wavelike aspects. Long waves have low energy, short-waves have high. The higher energy wavelengths (short-waves) are more penetrating i.e. more damaging. X-rays, gamma rays and cosmic rays have short wavelengths, 10"cm and less, and high frequency, 10'6 c/s and above and cause ionising radiation.
Others i.e. electric waves, radiowaves, micro waves, visible light, IR, UV and lasers have longer wavelength and less frequency and cause non-ionising radiation. Lasers are involved in visible light, IR and UV regions of the spectrum given below:
Ionising Radiation:
Ionising radiation means electromagnetic or corpuscular radiation capable of producing ions directly in its passage through matter. It is not visible by normal eyes. X-rays, Alpha, Beta, Gamma, Fast neutrons, thermal neutrons and radio nuclides are ionising radiation.
Protection Techniques include:
1.Control of exposure time and distance.
2.Shielding.
3.Wearing a film badge to check dose limit.
4.Pre and post employment medical test.
5.Prevention of radiation disease such as skin cancer, ulceration, dermatitis, cataract, damage to bones and bloodel etc.
6.Use of remote controlled containers.
7.Continuous monitoring and maintaining safe limits by engineering controls and PPE.
8.The sealed container should be leak proof.
CLICK HERE👉Safety from radiation and related information
Applications :-
Ionising radiation is used mostly in biological and chemical research, chemical pilot and production. It is used for curing, grafting, testing and evaluation, free radicals, cross linking, Polymerisation, disinfection, sterilisation, pasteurization etc. Product wise it is used in semiconductors, rubber, adhesives, spices, paints and coatings, membranes, fuels, lubricants, plastic piping, enzymes, cosmetics, pharmaceuticals, medical supplies, foods, flooring, furniture, textile, medical uses, agricultural uses etc.
Biological Effects and Controls:
Occasional small dose (e.g. X-rays photograph) does not affect much but small doses for a longer time or more frequent dose or higher dose may cause biological damage to a human body. Radiation energy passes through a body. The energy absorbed in a body is called dose. The time between the exposure and the first symptoms of radiation damage is called latent period. Human body always generates new cells replacing dead or damaged cells. But when ionising radiation causes more damage than the body's repair capacity, biological damage takes place. Injury to individual is called somatic effect and that being passed into future generations is called genetic effect. The biological effect is the destruction of reproduction capacity of a cell or carcinogenic effect) cancer) which is difficult to cure.
CLICK HERE👉Types of ionising radiation.
Biological effect of radiation can be reduced by -
1.Shielding the body portion (especially blood forming tissues and intestine)
2.Shielding by a portion between the source and the human body by a high density material such as lead or concrete wall. Thickness should be increased depending on intensity of radiation.
3.Less dense rate or fractionation of the dose and decreasing the dose level.
4.Low dose rate or fractionation of the dose and decreasing the dose level.
5.Diminishing O2 concentration in the tissues.
6.Reducing the exposure time.
7.Increasing the distance from source.
8.Using sealed source of radiation.
9.Monitoring the environmental exposure by various instruments such as film badge, Thermoluminescence dosimeters (TLD), pocket dosimeter, Geiger-Muller tubes (having automatic audible alarm), Ionising chambers, neutron and proton monitors and keeping them below the permissible threshold limits. Calibration techniques for instruments is most important.
10.Decontamination facilities.
11.Safe disposal of radioactive wastes.
Medical Surveillance: Exposure to radiation workers may not give any clinical signs. Therefore, according to ICRP, the medical surveillance workers should aim a
1. To assess the health of the workers.
2. To preserve good general health standards by monitoring the work conditions,
3. Exposure levels and the health of the workers and
4.To provide baseline information in case of accidental exposure or occupational Disease.
Decontamination:
CLICK HERE👉Decontamination
The Ionising radiation cannot be neutralised or interrupted. Therefore rapid decontamination is one of the best safety measures to protect man against possible or actual hazards or direct indirect radiation. The purpose of decontamination is to reduce its level below the safe level.
Following methods of decontamination are used:
1.Mechnical decontamination i.e. Removal of radioactive layer by scrubbing short blasting, washing by water etc.
2. Physical decontamination i.e. Evaporation, dilution, filtration, ultrasonic techniques, or allowing the half-time if it is in hours or upto 3 days.
3. Chemical decontamination i.e. Treating with acid, alkali, chelating compounds, ion-exchange resins etc.
4.Biological decontamination of sewage.
5.Decontamination of water, surface and clothing by selecting appropriate material, e.g 10% solution of citric acid followed by 0.5% solution of nitric acid to clean stainless steel surface, mineral acids to clean glass and porcelain vessels, replacement of concrete blocks etc.
6. Decontamination of perons by scrubbing the skin with warm water and soap and followed by use of surfactants and absorbents. 1 to 3% solution of hydrochloric and citric acid are also useful. Use of organic solvent is inadvisable. Cleaning for more than 10min is also not advisable.
Comments