The average value is the half-life of the radioactive source. For example:. The graph above shows the activity of a radioactive source over a period of time. Calculate the half-life of the source used in the experiment above. The half-life is the time taken for the activity to reduce by half. See also: Electromagnetic radiation ; Ionization potential.
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FullText PDF. Measurements were taken randomly in thirty 30 diff erent locations outside the building and thirty 30 locations inside diff erent buildings in the University. Results obtained for outdoor Dose rate ranges from 0. While the result for the indoor dose rate ranges from 0.
The highest value recorded for the outdoor radiation is from the university front gate which is. All these values are lower than the world safely limits of 0. This shows that the risk of ionizing radiation on the staff and students of the Federal University of Technology is minimal.
Natural radiation sources are classiied into two groups. The irst group is due to highly penetrating cosmic radiation mainly of glacial origin, while the second group is the terrestrial radiation from the primordial radionuclides, which have survived since the formation of the earth. The primordial radionuclides include the decay series of the radionuclides of Uranium— U and Thorium— Th and the single member chain of Potassium—40 40 K [1].
Long term exposure to ionizing radiation has severe health implications such as acute leukemia, lung cancer, pancreas, hepatic, skin, kidney cancers, cataracts, sterility and atrophy of the kidney [3].
In Nigeria, environmental radiation measurements started in October following the nuclear weapons testing carried out by France in Reganne in the Sahara region of Africa. This monitoring effort was motivated by the fear of likely fallout in densely populated countries in the tropical Africa [4].
Since then, some speciic or localized studies on radioactivity assessment in the environment have been done. It moved into its permanent site which is the location of this study in with a land mass of about hectares. It is one of the most populous universities in the South East with a population of about forty ive thousand 45, people both staff and students [5]. The map of the study area is shown below as figure 1. Eke and Emelue has previously studied the radiation emission and health hazard implications of refuse dump site in FUTO using the sodium iodide scintillation counter [5].
This present study focused not only on the refuse dump site, but on the entire school both outdoors and indoors. Exposure to ionizing radiation over extended period is known to result in non — leather mutation, which could increase the risk of cancer [6].
There is a linear, no — threshold LNT relationship between radiation dose and the occurrence of cancer [7]. When alpha particles, beta particles or gamma rays enter the GM tube the counter clicks and the count is displayed on the screen.
The number of counts per second or per minute is called the count rate. Measuring the background radiation. The background count rate is measured over a period of 20 minutes because of the random nature of radioactive decay. Dividing by 20 enables the average count rate per minute to be determined.
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