Radiations | Non-ionizing radiations

 RADIATIONS, NON-IONIZING RADIATIONS, RADIATIONS TYPES, RADIATION PROTECTION, AND RADIATION MANAGEMENT

Non-ionizing radiations

RADIATIONS, NON-IONIZING RADIATIONS, RADIATIONS TYPES, RADIATION PROTECTION, AND RADIATION MANAGEMENT

Radioactivity is the spontaneous emission of charged particles or photons from an atomic nucleus when in an unstable condition. The process is called nuclear transformation or disintegration or decay which results in loss of mass or charge depending upon the type of charged particles or photons emitted.

Radioactive substances are in common use in the oil and gas industry. Although there are known hazards associated with Radiation, with proper controls risk to health or the environment can be minimized. It is necessary for describing the origins of radiation, the types, and properties of the emitted radiation, and the mechanism by which radiant energy is deposited in various media. It is standard practice to optimize protection as ALARA (As Low as Reasonably Achievable). The types of radiation are:

·         Non-Ionizing Radiation

·         Ionizing Radiation

·         Naturally Occurring Radioactive Material (NORM)

RADIATION MANAGEMENT

Radiation management activities shall be performed in a standardized and coordinated manner and shall be prioritized based on the level of risk to a person’s health. Management of radiation shall be achieved through the following, at a minimum:

1.       Compliance with International including compliance with this Standard.

2.       Identification and preparation of an inventory of radioactive sources at each facility i.e. Radioactive Sources/Equipment Register as provided.

3.       Characterization of radiation exposures that are likely to contribute to exceedances of occupational exposure limits as per this Standard.

4.       Establishment of baseline levels of radiation at each facility including NORM

5.       NORM has been established, and NORM management guidelines for handling, storage, transportation, and disposal including NORM-contaminated equipment or waste shall be established

6.       Assessment, demarcation, and monitoring of site-specific Controlled Areas and Supervised Areas.

7.       Establishing and implementing radiation control strategies to reduce exposure to radiation sources in the work environment.

8.       Time, Distance, and Shielding - Minimizing exposure time, maximizing distance from the radiation source, and shielding employees from the radiation source.

NON-IONIZING RADIATION

Non-Ionizing Radiation is a generic term used to describe part of the electromagnetic spectrum covering two main regions, namely optical radiation i.e. ultraviolet, visible, and infrared, and electromagnetic fields i.e. power frequencies, microwaves, and radio frequencies as outlined in the subsections below.

1.       Optical Radiation

This covers visible Infrared ionizing radiations and Ultraviolet (UV) types. The term also covers lasers, but in any case, these emit UV or IR radiation.

The main sources of IR and UV are natural sunlight, but artificial sources include not limited to hot surfaces, arc welding, plasma cutting flames, halogen lamps/sodium light, and blowtorches.

It is important to recognize that several optical radiation sources in a typical workplace do not pose any risks to health, hence not necessitating a detailed risk assessment. Listed below are sources that are likely to produce insignificant exposures to optical radiation and hence pose minimal risks, provided that they are used correctly.

·         Ceiling-mounted fluorescent lighting with diffusers over the lamps

·         Computer or similar display screen equipment

·         Ceiling mounted compact fluorescent/halogen/tungsten lighting

·         UVA insect traps

·         Photocopiers

·         Indicator LEDs

·         Flame/Flare Scanners – used for flaring.

Optical radiations effects on Human Health

Optical radiation is absorbed in the outer layer of the body and its biological effects are mostly confined to the skin and eyes, although systemic effects may also occur. Different wavelengths cause different biological effects depending on which part of the skin or eye absorbs the radiation and the type of interaction involved. For example:

·         Photochemical effects dominate in the ultraviolet region

·         Thermal effects dominate in the infrared region

·         Laser radiation can produce additional effects characterized by very rapid absorption of energy by tissue and is a particular hazard for the eyes where the lens can focus the beam.

The biological effects of exposure to optical radiation can broadly be divided into acute (i.e. rapidly occurring) and chronic (i.e. occurring after prolonged and repeated exposures over a long period).

Generally, acute effects will only occur if exposure exceeds certain thresholds [i.e. exposure limits] and the risk of an adverse health effect will increase as exposure levels increase above the threshold limit. The majority of effects tabulated below will occur in the healthy adult working population at levels substantially above the exposure limits; however, abnormally photosensitive persons may suffer adverse effects below the exposure levels.

Chronic effects often do not have a threshold below which they will not occur. Consequently, the risk of these effects occurring cannot be reduced to zero; but the risk can be reduced by limiting exposure to acceptable levels.

2.       Electromagnetic Fields

An electromagnetic field is a force field generated around an electric current and is equivalent to an electric field and a magnetic field at right angles to each other. Common sources of electromagnetic fields include power lines, household electrical wiring, motor-driven instruments, computer screens, telecommunications and broadcasting facilities, and mobile telephones.

In contrast to electric fields, a magnetic field is only produced when a device is switched on and the current flows. Thus, the higher the current, the greater the strength of the magnetic field.

Electric fields are strongest close to a charge or charged conductor, but their strength rapidly diminishes with distance. Metal conductors provide an effective shield; and other materials such as bricks, walls, and trees, all provide shielding capability. When power lines are buried underground, electric fields at the surface are hardly detectable.

Low-frequency electric fields influence the human body just as they influence any other material made up of charged particles. When electric fields act on conductive materials, they influence the distribution of electric charges at their surface. They cause current to flow through the body to the ground.

Low-frequency magnetic fields induce circulating currents within the human body and the strength of these currents depends on the intensity of the outside magnetic field. If sufficiently large, these currents could cause stimulation of nerves and muscles or affect other biological processes

3.       Methodology for Measuring Non-Ionizing Radiation

Measuring non-ionizing radiation depends on the following cases:

·         Quick Overview: This method shall be applied when just the summation of nonionizing radiation level is required

·         Variable Frequency Band Scan: This method shall be applied when non-ionizing radiation levels are required by frequency within the scanned band.

4.       Measuring Electromagnetic Low Frequency (ELF)

·         Refer to the survey meter manufacturer’s instructions for the assembly and operation of the instrument. Note that the meter is factory-calibrated and must be returned to the manufacturer or the equivalent for periodic adjustments and recalibration.

·         Measure the dimensions of the area

·         Turn “ON” and zero the ELF electromagnetic fields survey meter.

·         Assure that the computer and VDT (and other peripherals such as a printer are turned “OFF.”

·         Using the tape measure, record levels of ELF electromagnetic fields at various distances from the computer and VDT screen, specifically including distances of 5 cm, 25 cm, 50 cm, and 1 m and heights of 50 cm, 1 m, 1.5 m, and 2 m.

·         Turn “ON” the computer and VDT and repeat measurements.

·         Complete a field monitoring data form, remembering to record your name, facility and location sampled, date, and EMF meter manufacturer and model.