The effect of neutron irradiation on the impedance of asbestos
Loading...
Date
2008-08-08
Authors
Journal Title
Journal ISSN
Volume Title
Publisher
Abstract
The project was concerned with finding the effect of neutron irradiation on the impedance of asbestos. Asbestos is used as an insulator of electricity in homes and industries; and in places of high temperatures and ionising radiations. Asbestos papers called ‘Terratex’ and ‘Novabestos’ have been found to be most suitable for thermal and electrical insulation in the air-cooled transformers and reactors rated for operation at elevated temperatures and under conditions where the liquid cooled counterpart is unsuitable. Thus even though there is a ban on the manufacture and use of asbestos in some countries, this ban has not been completely enforced in many countries.
The impedance of samples of asbestos ceiling tiles were measured with an Impedance/Gain Phase Analyzer. The samples were then irradiated with a constant neutron flux to different time intervals using the Miniature Neutron Source Reactor (MNSR) at Kwabenya, Accra. A control sample X was not irradiated. A second impedance measurement of the samples was made. Before irradiation the mean impedance of the asbestos samples was µ = 295.91kΩ, at a standard deviation of σ = 2.86kΩ. After irradiated with a mean neutron flux density of 11.25 x 1011ncm-2 for an average time interval of 2.25 hours, the impedance of the samples was found to be lowered to a mean impedance of = 281.22kΩ, at a standard deviation of sX = 5.42kΩ. A difference in sample means of about 14.69kΩ. At α = 0.05 and d.f. = 9, the critical value of t was -1.83 The calculated value was -8.58. The null hypothesis was rejected since -8.58< -1.83 lies in the critical region. Thus at a significance level of α = 0.05 (i.e. 95% confidence interval), the t test indicates that the difference in the sample means was significant. Thus, by irradiating an asbestos sample with neutrons the impedance will be lowered.
Description
A thesis submitted to the Department of Physics, Kwame Nkrumah University of Science and Technology in partial fulfilment of the requirements for the degree of Master of Science, Faculty of Physical Sciences.