IAEA Technical Meeting on Establishing a Network of Laboratories in the Field of Nuclear Instrumentation for Environmental Monitoring and other applications, 27-30 September 2010 Krakow, Poland
Status and Prospects In research Infrastructure Development In Nuclear Analytical
Spectrometry and Radiometric Instrumentation Methodologies for Environmental
Radiation and Associated Radioactivity Measurements and Modelling Studies in Kenya
Angeyo H.K., Patel J. P.s Achola S. 0., Odumo B. 0., Ogwari P., Otwoma D., Wepukhulu G. W. and Ntihabose L.
Department of Physics, University of Nairobi, P.O. Box 30197, Nairobi, Kenya.
Maina D. M., Mangala M. J. and Gatai J.G.
Institute of Nuclear Science & Technology University of Nairobi, P.O. Box 30197, Nairobi, Kenya.
Radiation Dosimetry Laboratory, Kenya Bureau of Standards, P.O Box 54974-00200, Nairobi, Kenya.
Hashes N. 0., matinee T. S., Mayaka. G. and Omari J.
Department of Physics, Kenyatta University, P.O. Box 43844-00100 Nairobi, Kenya.
Atando V. and Kinyua R.
Department of Physics, Jommo Kenyatta University of Agriculture and Technology, P.O. Box 62,000-00200 Nairobi, Kenya.
Mustapha A. 0.
Department of Physics, University of Agriculture, P.M.B. 2240 Abeokuta, Nigeria
Since 2002 the Department of Physics at the University of Nairobi has established the Applied Nuclear and Radiation Physics Division for graduate training in a variety of nuclear science fields and research, the major line of which is method development in analytical nuclear spectroscopy and radiometric instrumentation for trace chemical and radiogenic analysis problems in geothermics and environment utilizing multivariate chemometrics, geostatistical and hyperspectral imaging techniques. This is a relatively small academic division supported by a network of associate researchers of an enthusiastic group that work around a scant pool of shared instruments mainly X-ray fluorescence, Am-Be-source Neutron Activation Analysis, HPGe and NaI(T1)-based gamma-ray spectroscopy and liquid scintillation counting. The initiative built on our long tradition in research in nuclear geophysics and environmental radiation measurements. We research in applied radioactivity and radiation physics with emphasis on pollutant dispersion and fractionation modelling in the environment utilizing radiotracer methods. We also measure and analyze radon and radiogenic (and associated heavy metal) pollutants in ambient, aquatic and terrestrial matrices and develop novel computational techniques for study of their utility (for example use of radon in geothermal reservoir diagnostics in HBRA) and environmental impact. The use of products containing naturally occurring radioactive materials (NORM) such as minerals, quarry, sand, clays, etc especially from the High Background Radiation Areas (HBRA) is widespread, but they are not subject to radiological quality control. So is the heavy use of artificial fertilizers in farming in the highly densely populated catchments, as well as associated heavy toxic metal effluent discharge from industrial and artisanal activities; both NORM and TE-NORM get immobilized through dust lift and washout in the environment via riverine and wind transport thereby impacting the ecological quality and the food chain.
The research line on radiometric geothermics concerns the study and modelling of trace isotopic and element characteristics of geothermal field matrices associated with the High Background Radiation Areas (HBRA). Such areas provide a unique setting to understand the relations between geothermal characterizing trace elements and radiogenic signatures, which are a powerful diagnostic of geothermal resource potential; each geothermal system exhibits a unique radiogenic and/elemental composition and thus also unique characterizing model. We are exploiting the combined potential of trace radiogenic and element profiles of surficial hydrothermal expressions system matrices (rocks, soils, spring water, biota (biomonitors), ground water, thermal fluids, gas discharges, steam condensates, rock fluid inclusions, and sediment (reservoir, stream, river, lake) of geothermally active HBRA found in Kenya's Rift Valley for geothermal resource analysis and prospecting and environmental impact potential modeling. We model environmental impact risk (including low-level radioactive waste) during geothermal resource exploitation. In many areas of Kenya especially HBRA any each crust-modifying activity such as mineral extraction process has to be considered for radiological impact and radiation safety measurements. The line on spectroanalytical environmetrics is concerned with size-resolved radiative characterization of ambient aerosols applied to biosphere-atmosphere particulate exchange in relation to air quality management. The aim is to model and predict the radioactive aerosol dynamics as well as diagnose and classify aerosol-derived environmental risk (health, climate, pollution) episodes in the country in relation to meteorological parameters, season and geography (spatial variability). Our most extensive studies have been in the radiogenic characterization and estimation and modeling of radioactivity and radiation exposure impact due to habitation and occupational activities in HBRA.
These studies are supported by a small dedicated effort in gamma-ray detection efficiency modelling, particularly transfer of measured Ge detector gamma-ray efficiencies to computed efficiencies for complex geometries applied to low level environmental radioactivity measurements. Further, because radiation metrology is basic to achieving reliable dose measurements in all ionizing radiation applications. and it is also part of the radiological protection program framework that requires the use of reliable instruments and equipment that comply with the international standard performance criteria, metrological traceability and validation of our measurements are greatly enhanced by our collaborative research activities with the Secondary Standards Dosimetry Laboratory, at the Kenya Bureau of Standards, Nairobi.
Although nuclear spectrometric techniques have high analytical sensitivity, accuracy, speed and versatility for a wide variety of matrices, their practical utility to environmental radioactivity field studies is limited by a number of factors including the complexity of data collection, handling and analysis.
Further, separation of anthropogenic influences from natural geochemical background in the materials is an issue. Therefore we use chemometrics methods, which reduce the complexity and increase the information gained - the range and complexity of problems that can be solved by spectroscopy is tremendously increased by chemometrics. Chemometric methods have the ability to extract important features (underlying chemical or physical phenomena) from complex multivariate data and once developed for a specific application to perform rapid and stable analyses. In our research, while chemometrics is used to explore relationships between the chemistry of the matrices known to correlate with the measured property and for data mining, geostatistics is used to analyze, characterize, predict and model phenomena spread in space and/ time; to show the results in maps where the distribution of each variable is represented, and to find combinations of variables which reflect the cause of the distributions.
Recently we began to combine conventional imaging (utilizing modified optical microscopy) and spectroscopy (called hyperspectral imaging) to simultaneously acquire spatial and spectral information from the measured matrices. This information-rich technology is a powerful process analytical tool for rapid, non-contact and non-destructive analysis and is more amenable to chemometrics analysis.
In this paper we highlight our experiences, successes (by reporting the main findings) and challenges so far building this unique research infrastructure around only a small qualified and networked staff. We discuss how this research network is assisting to develop Kenya's human resource capacity (the country's economic blue print includes research and use of atomic energy for peaceful purposes) toward development of nuclear power (and attendant technological; specifically, towards enhancing research capacity for Kenya's planned first research reactor as a prelude to having nuclear power generation plant.