INTRODUCTION
1.1 BACKGROUND OF STUDY
Industrial radiography uses x-rays and Gamma rays to produce a radiograph of specimen or material, showing any changes in thickness, defect (internal or external), and assembly details, to ensure optimum quality. This application is called Non-destructive testing.1
Three types of radiation sources are typically available for such purposes.
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In another industrial application, there are systems specifically designed to focus intense beam of high energy electrons that melt and bond metal under vacuum conditions and these electron-metal interactions can produce x-rays as a by-product of the bonding process. Such systems are called Electron beam welders. Beam current and high voltages are typically in the range of 20-200milliAmpers and 120-450kilovoltage respectively. Consequently, the operations of electrons beam welders present a potential for exposure to x-rays and electrons, which are types of ionizing radiation.
In general, the interaction of ionizing radiation with matter is probabilistic, that is, there may or may not be an interaction. The interaction with individual cells of living organisms may be direct or indirect. At the cellular level, direct interaction with Deoxyribonucleic acid (DNA), or other constituents can cause damages. Various possibilities exist for the fate of cells exposed to ionising radiation.3
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Thus, exposure to ionising radiation has the potential to cause early or late adverse health effect. This is why the radiation risks associated with industrial radiography operations need to be managed. This study is designed to ascertain the radiation protection procedures adopted by Saipem Contracting Nigeria Limited (SCNL)
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. This may be due to close proximity of the control point to the source or inadequate use of radiation monitoring devices.
1.3 PURPOSE OF STUDY
1.3.1 General Purpose
To assess radiation protection practices among Non-destructive testing personnel in SAIPEM CONTRACTING NIG LTD (SCNL).
1.3.2 Specific Objectives:
1.4 SIGNIFICANCE OF STUDY
Hypothesis one
Ho:
The rate of utilization of radiation monitoring devices is independent of the gender of the radiation workers in SCNL.
Hypothesis two
Ho:
The rate of utilization of radiation monitoring devices during field operations is independent of the level of education of workers in SCNL.Hypothesis three
Ho
The rate of utilization of radiation monitoring devices during field operations is independent of the basic profession of the radiation workers in SCNL.
Hypothesis four
Ho
The rate of utilization of radiation monitoring devices during field operations is independent of the duration of radiation workers’ duration of practice.
1.5 SCOPE OF STUDY
This study related to all types of industrial radiography equipment and facilities in SAIPEM CONTRACTING NIG LTD in Port-harcourt, River state. It covered radiation protection and safety procedures in Saipem Contracting Nig. Ltd, and lasted for a period of three months.
OPERATIONAL DEFINITION OF TERMS
ALPHA RADIATION:A particulate form of nuclear radiation that consists of a helium nucleus without its electrons. An alpha particle has a charge of +2 and can travel only short distances.
APPARATUS FOR GAMMA RADIOGRAPHY:Means an apparatus, including its exposure container and accessories, designed to enable gamma radiation emitted by a sealed source to be used for industrial radiography.
BETA RADIATION:A particulate form of nuclear radiation that consists of anelectron. A beta particle has a charge of -1 and can travel millimeters to centimeters in tissue.
CALIBRATED:Means an instrument, component or system that has undergone the measurement of, or adjustment to, to ensure its accuracy or response is acceptable and the processes are performed by an agency recognized and approved by the appropriate authority;
COLLIMATOR: Means a device to limit a useful beam to the required cross-sectional area of interest.
CONTAMINATION:The presence of unconfined radioactive material on orwithin any object where it is not desired.
CONTROLLED AREA: Means any area in which specific protection measures and safety provisions are or could be required for controlling normal exposures or preventing the spread of contamination during normal working condition, and preventing or limiting the extent of potential.
DETERMINISTIC EFFECT:An effect in which the severity of the symptoms are related to the dose of radiation. Example: Acute Radiation Syndrome.
DOSE:A calculated measurement of the amount of energy imparted by ionizing radiation. Dose is relative to the size of the source, the radionuclide or radiation machine involved, and the length of time and circumstances of the exposure.
DOSIMETRY:Devices that measure accumulated, individual dose. These devices are usually worn by workers who handle radioactive materials or work in areas where radiation is present.
EXPOSURE:The irradiation of any object.
exposure container” means a shield in the form of a container designed to allowcontrolled use of gamma radiation and employing one or more sealed sources;
FULLY ENCLOSED SITES: An enclosed site such as a shielded room, the boundary of which is formed wholly by suitably designed physical barriers and access is controlled by physical barriers.
GAMMA RADIATION:A form of electromagnetic radiation that is nuclear inorigin. It can travel many centimeters in tissue.
GRAY (GY):The Systems International (SI) unit of absorbed dose, equivalent to100 rads or 1 joule per kilogram.
HALF-VALUE-LAYER (HVL):Means thickness of a certain material required toreduce radiation of a known energy range and intensity, to half of its originalintensity. This can also be expressed as the quotient of 0.693 by the linearattenuation coefficient of the material;
INDUSTRIAL RADIOGRAPHY: a non-destructive technique of examining structure of materials utilizing x-rays, neutron or gamma rays.
LEAKAGE RADIATION: means all radiation emitted from the exposure container or x-ray tube housing other than the useful beam;
RAD:An acronym standing for Radiation Absorbed Dose. An exposure of one rad results in the absorption of 100 ergs of energy per gram of tissue exposed.
RADIOGRAPHIC EQUIPMENT: Includes x-ray equipment for industrial radiography,apparatus for gamma radiography and pipeline crawler equipment.
SOURCE:Means any material or irradiating apparatus which emits x or gamma radiation suitable for industrial radiography.
SHUTTER:A device fixed to the x-ray tube housing or exposure container capable of intercepting the useful beam.
SOURCE CHANGER: A device designed and used for replacement of sealed source in an exposure container.
STOCHASTIC EFFECT:An effect in which the probability of occurrence is related to the dose of radiation. Examples: genetic defects, cancer.
THERMOLUMINESCENT DOSIMETER (TLD): An extremely accurate device to measure and provide a permanent record of exposure to radiation.
USEFUL BEAM:Means that part of the radiation which passes through the window, aperture, cone or other collimating device of the x-ray tube or exposure container.
X-RADIATION:A form of electromagnetic radiation arising from the electron shells of an atom.