THE SCREENING INDOOR RADON AND PRELIMINARY STUDY OF INDOOR THORON CONCENTRATION LEVELS IN KUWAIT.

Indoor measurements of radon and thoron in Kuwait were conducted during the years 2015 and 2016. In this study, 65 dwellings were selected for the long-term radon-thoron survey using passive nuclear track monitors. The monitors (at least one) were used at various locations in the dwellings for 83-306 days. Some measurements were also repeated at the same locations in different seasons. This current study is a preliminary thoron survey with relatively small sample size. The results showed that the range of thoron concentration was from below the lower limit of detection to 35 Bq m-3, whereas the range of radon concentration was within 10-202 Bq m-3. Furthermore, 22% of the radon results exceeded the WHO radon reference level of 100 Bq m-3. The analysis of variance showed a correlation between indoor radon concentration and the season. However, the thoron measurements were rather limited and the values were low. In addition, the relationship was investigated between radon and thoron concentrations involving the floor levels and the type of ventilation systems used.

AREA MONITORING OF AMBIENT DOSE RATES IN PARTS OF SOUTH-WESTERN NIGERIA USING A GPS-INTEGRATED RADIATION SURVEY METER.

A radiation monitoring system comprising a Geiger-Muller counter connected to a smart phone via Bluetooth was used for a dose rate survey in some parts of south-western Nigeria. The smart phone has the Geographical Positioning System, which provides the navigation information and saves it along with the dose rate data. A large number of data points was obtained that shows the dose rate distribution within the region. The results show that the ambient dose rates in the region range from 60 to 520 nSv -1 and showed a bias that is attributable to the influence of geology on the ambient radiation dose in the region. The geology influence was demonstrated by superimposing the dose rate plot and the geological map of the area. The potential applications of the device in determining baseline information and in area monitoring, e.g. for lost or abandoned sources, radioactive materials stockpiles, etc., were discussed in the article, particularly against the background of Nigeria's plan to develop its nuclear power program.

Application of the Monte Carlo method for the efficiency calibration of CsI and NaI detectors for gamma-ray measurements from terrestrial samples.

Gamma-ray measurements in terrestrial/environmental samples require the use of high efficient detectors because of the low level of the radionuclide activity concentrations in the samples; thus scintillators are suitable for this purpose. Two scintillation detectors were studied in this work; CsI(Tl) and NaI(Tl) with identical size for measurement of terrestrial samples for performance study. This work describes a Monte Carlo method for making the full-energy efficiency calibration curves for both detectors using gamma-ray energies associated with the decay of naturally occurring radionuclides (137)Cs (661keV), (40)K (1460keV), (238)U ((214)Bi, 1764keV) and (232)Th ((208)Tl, 2614keV), which are found in terrestrial samples. The magnitude of the coincidence summing effect occurring for the 2614keV emission of (208)Tl is assessed by simulation. The method provides an efficient tool to make the full-energy efficiency calibration curve for scintillation detectors for any samples geometry and volume in order to determine accurate activity concentrations in terrestrial samples.

A simple bubbling system for measuring radon (222Rn) gas concentrations in water samples based on the high solubility of radon in olive oil.

Based on the different levels of solubility of radon gas in organic solvents and water, a bubbling system has been developed to transfer radon gas, dissolving naturally in water samples, to an organic solvent, i.e. olive oil, which is known to be a good solvent of radon gas. The system features the application of a fixed volume of bubbling air by introducing a fixed volume of water into a flask mounted above the system, to displace an identical volume of air from an air cylinder. Thus a gravitational flow of water is provided without the need for pumping. Then, the flushing air (radon-enriched air) is directed through a vial containing olive oil, to achieve deposition of the radon gas by another bubbling process. Following this, the vial (containing olive oil) is measured by direct use of gamma ray spectrometry, without the need of any chemical or physical processing of the samples. Using a standard solution of 226Ra/222Rn, a lowest measurable concentration (LMC) of radon in water samples of 9.4 Bq L(-1) has been achieved (below the maximum contaminant level of 11 Bq L(-1)).

Measurements of 210Pb concentrations in airborne in Kuwait.

The concentrations of 210Pb in the atmosphere of Kuwait City have been monitored over a period of five years (January 1994 to December 1998) using cellulose air filters for analysis with liquid scintillation counting forgross beta. Results show that the distribution of daily averaged 210Pb concentrations varied from 0.002 to 2.53 mBqm(-3) with an average of 0.896 mBqm(-3) and a geometric mean of 0.687 mBqm(-3). The study suggests that the existence of 210Pb in air in Kuwait originates mainly from re-circulated fraction of 210Pb which was already deposited on ground surface, not from direct decay of radon. The long-term trend pattern for the five years shows a seasonal variation with maximum concentrations occurring in the autumn season.

Radioactivity concentrations in sediments and their correlation to the coastal structure in Kuwait.

Gamma-ray spectrometric measurements were performed on sediment samples from the coast of Kuwait to study the concentration of natural as well as man-made radioactive sources. The coast of Kuwait, which extends for some 170 km is mainly soft sedimentary colitic limestones or sandstones, overlaid in many areas with beach or wind-blown sand. In the north, suspended material from the Shatt Al-Arab delta has settled to form extensive soft areas of intertidal mud within Kuwait Bay. Forty samples were taken at different points along the coast in undisturbed areas at intervals of about 5 km. Collection was carried out during low-tide, where it was possible to collect sediments from the wet region that was covered by seawater during the high tide. At each of the sample sites, a sampling area of about 1 m2 was considered. Samples collected from the north were of a muddy nature, whereas the southern samples were sandy. All samples were left to dry in open air before drying in the oven at 105 degrees C for 2-3 days to remove all water content. The radioactivity in southern areas reaches about one half of the values commonly assigned as the world average. In the northern areas, higher radioactivity concentrations are found but are still below the international levels.

Variations in 7Be concentrations in the atmosphere of Kuwait during the period 1994 to 1998.

The Beryllium-7 (7Be) concentrations in the atmosphere of Kuwait, as found by gamma-ray measurements for 243 air filters collected over a five-year period, produced variable values ranging from 0.2 to 14.9 mBq/m3 with a behavior pattern which has oscillatory characteristics, with increased activities occurring in the summer months of each year. The annual levels of occurrence of 7Be were found to be correlate with the cyclic pattern resulting from the eleven-year temporal variations associated with the solar activity.

Comparative study of desert truffles from Kuwait and other countries in the Middle East for radionuclide concentration.

Concentrations of some radionuclides, including 137Cs, in desert truffles in Kuwait were studied and compared with similar samples from other countries in the Middle East, namely Iran, Egypt, and Tunisia. In addition, sand samples from Kuwait were assayed to calculate the transfer factor of the radionuclides under consideration. The measured concentrations of 40K, 226Ra, and 137Cs show that 137Cs is much higher in Egyptian samples, whereas 40K is much lower in samples from Tunisia. The average effective dose equivalent calculated for the Kuwaiti population according to their diet habits was found to be in the range 0.14-0.23 microSv/a. The results are compared with values from other countries.