Assessment of Terrestrial Radioactivity Distribution in Olkaria Geothermal Field, Kenya

Authors(4) :-Solomon Namaswa, Nicholas Mariita, Douglas Onyancha, Judith Kananu

Geothermal energy has played a major role in energy supply in Kenya and even overtaking other sources of energy. However, utilization of subsurface fluids need comprehensive examination and the results communicated to the general public. This is because natural radiation is considered critical during earth processes since the gradual disintegration of naturally occurring radioactive elements account for almost half of the energy that brings about volcanology processes. This therefore implies that the slow decay of radioactive elements aids in generation of temperature gradient beneath the earth surface. In this survey, NaI(Tl) gamma-ray spectrometer was employed in determination of the NORMs levels within the Olkaria geothermal field and estimated the hazards indices that arise from the decay of these products in relation to other physico-chemical parameters such as temperature, TOC, pH and specific gravity. The study revealed that 238U, 232Th and 40K had average levels at 66.42±16.02Bqkg-1, 46.92±9.52Bqkg-1 and 512.84±226.49Bqkg-1 respectively while 80.56±17.77nGyh-1, 0.1mSvy-1, 0.47and 172.79±30.37Bq/Kg were the mean values for absorbed dose rates, annual effective dose rate, hazard index and radium equivalent respectively. Also a weak positive correlation between pH, TOC and s.g and the concentration of the three radioactive elements was observed. From the obtained results, the studied hazard indices were below the world acceptable safety limits and therefore human exposure to radiation is within safety levels. Also change in physicochemical parameters does not affect the radionuclide concentrations. This shows that the exploitation of geothermal energy in Olkaria has not affected the activity concentration level of238U, 232Th and 40K and the hazard indices.

Authors and Affiliations

Solomon Namaswa
Geothermal Training and Research Institute, Dedan Kimathi University of Technology, Nyeri, Kenya
Nicholas Mariita
Geothermal Training and Research Institute, Dedan Kimathi University of Technology, Nyeri, Kenya
Douglas Onyancha
Department of Chemistry, Dedan Kimathi University of Technology, Nyeri, Kenya
Judith Kananu
Department of Chemistry, University of Nairobi, Kenya

Annual Effective Dose, Internal Hazard Index, Radium Equivalent, Kenya.

  1. Alfe, D., Gillan, M. J., Vocadlo, L., Brodholt, J. and Price, G. D. (2002). The Ab Initio Simulation of the Earth's. Phil, Trans. R. Soc. Lond. 360, 1227-1244
  2. Kelley, S. (2010). Geothermal Energy, Lite Geology. New Mexico Bureau of Geology & Mineral Resources, a Division of New Mexico Tech
  3. Fowler, C.M.R. (1990). The Solid Earth: An Introduction to Global Geophysics. Cambridge University Press.
  4. Turcotte, D. L. and Schubert, G. (2002). Geodynamics (2nd Ed.). Cambridge, England, UK: Cambridge University Press. p. 137.
  5. Arevalo, R. D., W. F. McDonough, and M. Luong. (2009). The K/U ratio of the silicate Earth: Insights into mantle composition, structure and thermal evolution. Earth and Planetary Science Letters, 278: 361-369
  6. Ouma, P.A. (2009). Geothermal Exploration and Development of the Olkaria Geothermal Field. Presented at Short Course IV on Exploration for Geothermal Resources, organized by UNU-GTP, KenGen and GDC, at Lake Naivasha, Kenya.
  7. Kandie, R.J. (2014). Eastern Rift Structural Geology-Tectonics, Volcanology and Geothermal Presented at Short Course IX on Exploration for Geothermal Resources, organized by UNU-GTP, GDC and KenGen, at Lake Bogoria and Lake Naivasha, Kenya,.
  8. Omenda, P.A. (2008). Status of Geothermal Exploration in Kenya and Future Plans for Its Development. Presented at Short Course III on Exploration for Geothermal Resources, organized by UNU GTP and KenGen, at Lake Naivasha, Kenya.
  9. Lagat, J.K. (2004). Geology, Hydrothermal Alteration And Fluid Inclusion Studies Of Olkaria Domes Geothermal Field, Kenya. Msc. Thesis, University of Iceland 
  10. Ramasamy V, Senthil S., Meenakshisundaram V. and Gajendran V. (2009). Measurement of Natural Radioactivity in Beach Sediments from North East Coast of Tamilnadu, India, Resource Journal on Appropriate Technology and Scientific Engineering, 1 (2): 54-58.
  11. Iqbal, M., Tufail, M., & Mirza, S. M. (2000). Measurement of natural radioactivity inmarble found in Pakistan using NaI(Tl) gamma-ray spectrometer. Journal of Environmental Radioactivity, 51, 255-265.
  12. Yu, K. N., Guan, Z. J., Stoks, M. J., & Young, E. C. (1992). The assessment of natural radiation dose committed to the Hong Kong People. Journal of Environmental Radioactivity.
  13. Turhan, S., & Varinlioglu, A. (2012). Radioactivity measurement of primordial radionuclides in and dose evaluation from marble and glazed tiles used as covering building materials in Turkey. Radiation Protection Dosimetery 546-555.
  14. Beretka, J., & Mathew, P. J. (1985). Natural radioactivity of Australian building materials, waste and by-products. Health Physics, 48, 87-95.
  15. UNSCEAR, (2000). Sources and Effects of Ionizing Radiation; United Nation Scientific Committee on the Effects of Atomic Radiation Annex A.B. New York.
  16. Kananu, J., Madadi, V.O. and Kamau, G.N. (2014). Impact of Long Term Inorganic Fertilization with Emphasis on Heavy Metals, Soil pH and Total Organic Carbon on Maize Farm Soils in Trans Nzoia, Kenya. The International Journal of Science & Technology, 2(11), 183-188
  17. Tiessen H. and J.O. Moir. 1993. Total and Organic Carbon. In: Soil Sampling and Methods of Analysis. M.E. Carter, Ed. Lewis Publishers, Ann Arbor, MI. p. 187-2 11.
  18. Namaswa, S.W., Okoth, C.O. and Makori, B. (2017). Analysis of Natural Radioactivity and Radiation Exposure Levels in Eburru Geothermal Field, Kenya. IJSRSET, 4(1), 841-846
  19. Ramola, R.C., Choubey, V.M., Ganesh, P., Gusain, G.S., Tosheva, Z. and Kies, A. (2011). Radionuclide Analysis in the Soil of Kumaun Himalaya, India, Using Gamma Ray Spectrometry. Current Science, 100 (6): 25
  20. Patel, J.P. (1991). Environmental Radiation Survey of the Area of High Background Radioactivity of Mrima Hill of Kenya, Discovery and Innovation 3(3): 31-36.
  21. Achola, S.O., Patel, J.P., Mustapha, A.O. and Angeyo, H.K. (2012). Natural Radioactivity in the High Background Radiation Area of Lambwe East, Southwestern Kenya, Radiation Protection Dosimetry, 2, 1-6.
  22. Otwoma, D., Patel, J.P., Bartilol, S.K. and Mustapha, A.O. (2013). Estimation of Annual Effective Dose and Radiation Hazards Due to Natural Radionuclides in Mount Homa, Southwestern Kenya, Radiation Protection Dosimetry, 2013: 1-8.
  23. Tambo, P. S. (2014). Multivariate Characterization of Natural Radioactivity Systematics in Lake Magadi Basin Geothermal System In Relation To Quality of Trona Deposits. Msc. Thesis, University of Nairobi
  24. ICRP, (2007). The 2007 Recommendations of the International Commission on Radiological Protection. ICRP Publication 103. Ann. ICRP 37: 2-4
  25. Nelson, D.W., and Sommers L.E. (1996). Total Carbon, Organic Carbon, and Organic Matter: Methods of Soil Analysis, 2nd Ed, 539-580

Publication Details

Published in : Volume 4 | Issue 4 | March-April 2018
Date of Publication : 2018-04-30
License:  This work is licensed under a Creative Commons Attribution 4.0 International License.
Page(s) : 810-817
Manuscript Number : IJSRSET184419
Publisher : Technoscience Academy

Print ISSN : 2395-1990, Online ISSN : 2394-4099

Cite This Article :

Solomon Namaswa, Nicholas Mariita, Douglas Onyancha, Judith Kananu, " Assessment of Terrestrial Radioactivity Distribution in Olkaria Geothermal Field, Kenya, International Journal of Scientific Research in Science, Engineering and Technology(IJSRSET), Print ISSN : 2395-1990, Online ISSN : 2394-4099, Volume 4, Issue 4, pp.810-817, March-April-2018.
Journal URL : http://ijsrset.com/IJSRSET184419

Article Preview

Follow Us

Contact Us