Examination of Natural Radioactivity in Building Material in Katsina State Using Gamma Ray Spectroscopy.
ABSTRACT
Twenty Concrete Blocks from (20) different Local Governments in Katsina state was measured using Gamma Ray Spectroscopy with NaI (TL) detector. Three naturally Occurring Radionuclides and their activity concentrations were determined, are 40K 226Ra, and 232Th.
Their activity Concentrations ranges from 40K 46.11 ± 826.59 to 46.11± 8.55 Bq/kg, (226Ra) ranged from10.19 ± 2.43Bq/kg to 75.09 ± 4.98 Bq/kg and (232Th) ranged from 2.77 ± 9.59Bq/kg to 123.49 ± 9.35Bq/kg respectively.
The highest value also determined from 40K was (826.59 ± 4.82Bq/kg), the highest value of 226Ra was 75.09 ± 4.98Bq/kg , the highest value for (232Th) is 123.49 ± 9.35 Bq/kg respectively.
The Radium Equivalent mean value was obtained from the measurement ranged from (34.8 ± 1.59 to 411.26nGT/h), The absorbed dose rate in air with its mean value was obtained, ranges from (147.16 ± 3.55nGy/h).
The limit set in the OECD report (370Bq/kg) and UNSCEAR, 2000 (24 to 160nGy/h). The annual effective dose obtained, ranges from 0.04 ± 0.001 to 0.20 ± 0.0001mSv/y, with mean value 0.187 ± 0.0005mSv/y.
Recommended limit 0.460 mSv/y set by ICRP, 2007 for terrestrial radiation. The evident that the Results give lower value when compared with 1mSv/y for Public exposure (ICRP, 2007).
TABLE OF CONTENTS
Title page – – – – – – – – – i
Certification – – – – – – – – – ii
Dedication – – – – – – – – – iii
Acknowledgements – – – – – – – – iv
Abstract – – – – – – – – – v
Table of content (TC) – – – – – – – – vi
List of tables (LT) – – – – – – – – – x
List of figure – – – – – – – – – xi
List of abbreviation – – – – – – – – xii
CHAPTER ONE: INTRODUCTION
1.0: Introduction – – – – – – – – 1
1.1: Background of the study – – – – – – 1
1.2.0: Natural Radioactivity in the Environment – – – – 4
1.2.1: Potassium -40 (40K) – – – – – – – 4
1.2.2: Uranium Decay Series – – – – – – 4
1.2.3: Thorium Decay Series- – – – – – – 5
1.2.4: Radon – – – – – – – – – 5
1.3.0: NORM in Building Materials – – – – – 5
1.4.0: Component of Cement Block – – – – – – 7
1.4.1: Sand – – – – – – – – – 7
1.4.2: Cement – – – – – – – – 7
1.4.3: Gravel Aggregate – – – – – – – 8
1.4.4: Concrete – – – – – – – – 9
1.5.0: Statement of the problems – – – – – – 9
1.6: Aims and Objectives – – – – – – – 10
1.7: Significant of the Study – – – – – – 11
1.8: Scope and Limitation of the study – – – – – 11
1.9: limitations – – – – – – – – 11
1.10: List of local Government in Katsina State – – – 12
CHAPTER TWO: LITERATURE REVIEW
2.0: Literature review – — – – – – – 14
2.1: History – – – – – – – – 14
2.2: Sources of Natural Occurring Radioactive Materials (NORM) – 16
2.2.1: Cosmic radiation – – – – – – – 16
2.2.2: Terrestrial radiation – – – – – – – 18
2.2.3: Man-made sources – – – – – – 19
2.2.4: Members of the public – – – – – – 19
2.2.5: Occupationally exposed individuals – – – – – 20
2.3: NORMS Isotopes – – – – – – – 20
2.4: Health Risk of Norms – – – – – – – 21
2.4.1: Standard and regulations of radiation exposure – – – 23
2.5: Types of Radioactive decay – – – – – – 25
2.5.1: Alpha particles decay – – – – – – – 25
2.5.2: Beta decay – – – – – – – – 26
2.5.3: Gamma decay – – – – – – – – 26
2.6: Gamma – ray interaction with matter – – – – – 26
2.6.1: Photo electric effects – – – – – – – 27
2.6.2: Campton scattering – – – – – – – 28
2.6.3: Pair Production – – – – – – – 29
2.6.4: Biological effects of Radiation – – – – – 29
2.6.5: Radium – 226 (226Ra) – – – – – – 30
2.6.6: Potassium-40 (40K) – – – – – – – 31
2.6.7: Thorium-232 (232Th) – – – – – – – 32
2.6.8: Cancer Treatment – – — – – – – 33
2.7.0: Review on related literature – – – – – – 33
CHAPTER THREE: MATERIALS AND METHOD
3.0: Materials and Method – – – – – – 38
3.1.0: Material – – – – – – – – 38
3.2.0: Method of making cement blocks – – – – – – 38
3.2.1: Size and structure of cement blocks – – – – – 39
3.3: Samples Collection – – – – – – – 40
3.4: Samples preparation – – – – – – – 41
3.5: Energy Calibration of Sodium Iodide Thallium – – –
Gamma spectroscopy system – – – – – – 44
CHAPTER FOUR: RESULT AND DISCUSSION
4.0: Result and Discussion – – – – – – – 46
4.1: Experimental Result – – – – – – – 46
4.2: Activity analysis – – – – – – – 50
4.2.1: The radium equivalent – – – – – – 50
4.2.2: Absorbed dose in Air – – – – – – – 50
4.2.3: Annual Effective Dose Rate – – – – – – 51
4.3: Statistical analysis of the samples- – – – – – 53
CHAPTER FIVE: CONCLUSION AND RECOMMENDATIONS
5.0: Conclusion and Recommendations – – – – – 59
5.1: Conclusion – – – – – – – – – 59
5.2: Limitations – – – – – – – – 59
5.3: Recommendations – – – – – – – 60
REFERENCES – – – – – – – – 61
APPENDICES – – – – – – – – 65
INTRODUCTION
1.1 Background of the study
The world is naturally radioactive, and around 90% of human radiation exposure arises from natural sources such as cosmic radiation, exposure to radon gas and terrestrial radiations.
Significantly, natural occurring radionuclides present in soil are 238U, 232Th,40K (Harb et al.,2010).
However, since these radionuclides are not uniformly distributed, the knowledge of their distribution in soils and rocks play important role in radiation protection and measurement.
Some of these exposures are fairly constant and uniform for all individual persons everywhere, for examples, the dose acquire from ingestion of 40K in foods. Other exposure varies depending on location.
Cosmic rays, for example, are more intense at higher altitudes and concentration of uranium and thorium in soils are elevated in localized areas.
High level of uranium and its decay products in soil and rock, and thorium in sands are the main sources of high natural background of radiations that have been identified in several areas of world (UNSCEAR, 2000).
Most building materials contain various amount of radioactivity, for example materials derived from rock and soil that contains natural radionuclides of Uranium (238U), thorium (232Th) and isotope of potassium40K series (McAulary et al., 1989).
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