Xenon radioisotopes are one of the products of uranium nuclear fission. These radioisotopes are released in the form of gas in the process of dissolving the uranium target to extract 99Mo. This research aims to measure the activity of released xenon radioisotopes. For this, radioxenon is separated from other fission products using activated charcoal and purified after passing through a carbon molecular sieve. Pure radioxenon is directed into the measurement chamber and determined by an HPGe detector. Calibration of the detector efficiency has been performed via experimental and simulation (using MCNPX27e code) and the difference was less than 22%. In this way, the average activity of 100 cc of radioxenon gas at the moment after irradiation was equal to 54225 ±2272 Bq.

The method of optimal measurement counting time in Gamma spectrometry for soil samples was studied. Gamma spectrometry was done based on minimum detectable activity using the HPGe-p type with efficiency of 30% and FWHM 1. 7keV (for 1. 33 MeV 60Co). The samples were IAEA-RG Th-1, IAEA-RGU-1 and IAEA-RGK-1 prepared in bottles. The measurements were done for 12 different counting times from 5 min to 36 hour. The minimum detectable activity (MDA) was determined for daughters’ of 232Th, 238U, 235U and radionuclide 40K. The counting time in which the changes of the MDA is less than 0. 05 Bq/kg· h was considered as the optimal counting time.

A useful benchmark for the reliability of gamma spectrometry results is to provide measurement uncertainty. Due to the importance and necessity of radiation monitoring in water resources, this research has been oriented toward providing measurements of the gamma-emitting radionuclides along with introducing the expression for the uncertainty that appeared in these measurements. To calculate the uncertainty of the activity measurements in water, a sample, where its radioactive elements were obtained from the PolAtom Company, was used. The calculations were performed based on the 661 keV peak of 137Cs radionuclide and a high-purity germanium detector (HPGe). The investigations show that the factors affecting the measurement uncertainty are composed of two parts, including counting with the gamma spectroscopy system and sample preparation, where each of these parts comes from several sources of uncertainty such as uncertainties associated with the counting process, efficiency calibration, emission probability, the counting correction factors, and the mass measurement. The results of analyses show that the relative uncertainty is about 3. 7% (Coverage factor = 1) for a water sample with an activity of 425 Becquerel from 137Cs.

Ion beam analysis (IBA) has been widely used for fast, sensitive, multi-elemental and nondestructive analysis without any sampling, especially for the pigment analysis. External beam PIXE and PIGE techniques are applied simultaneously to large archaeological samples, kept at atmospheric pressure during the irradiation. In this research work, an external beam was used for the analysis of lapis lazuli samples and the azure color of the archaeological tile. By comparing the spectra, we found that cobalt is used to create azure color in archaeological tiles, while in lapis lazuli, no cobalt is observed and sodium is the characteristic element of the azure color in the lapis lazuli samples. It was also shown that lapis lazuli can be identified by the ion beam analysis.

The concentration of naturally occurring radioactive materials (NORM) in surface water and irrigation wells is measured using gamma ray spectrometry by HPGe detector. Measurement was carried out for samples that were collected over seventeen points in Tehran city and its suburbs. The samples were prepared in compliance with the principles from irrigation wells of city. The specific radioactivity of Ra-226, Th-232 and K-40 were measured and the results from different locations covered a range with the minimum being below “ minimum detectable activity” up to maximum of 4. 04, and 6. 85 and 4. 7 Bq per liter of water, respectively. The accumulation of radioactive materials in the samples from southern areas of Tehran was more than that of central areas. Also, concentration of Ra-226 in all the samples was less than the Derived Release Limit of Canada and Environmental Protection Agency standard threshold.

Background: The knowledge of distribution of radionuclides and background radiation levels in the environment is important for assessing the effects of radiation exposure due to both terrestrial and extra-terrestrial sources. Materials and Method: In-situ gamma dose survey and gamma spectrometry was employed to investigate background radiation levels in Ijebu-Ife. Results: In-situ gamma dose rates vary from 0. 02 to 0. 10 μ Sv/hr with mean value of 0. 05 μ Sv/hr which is less than 0. 133 μ Sv/hr, recommended by the ICRP. The resulting annual effective dose was below 1 mSv/yr maximum permissible limit for the general public set by the UNSCEAR, 2000. The activity concentrations of the three naturally occurring radionuclides in soils ranged from Below Detection Level (BDL) to 320. 11 ± 28. 53, 9. 11 ± 1. 65 and 8. 55 ± 0. 95 Bq/kg with mean values of 119. 05 ± 11. 24 Bq/kg, 4. 44 ± 1. 01 Bq/kg and 4. 55 ± 0. 62 Bq/kg respectively which are lower than the average values of 400, 35, and 30 Bq/kg recommended by the UNSCEAR, 2000 for 40K, 226Ra, and 232Th respectively. The mean computed values for absorbed dose rate, annual effective dose and radium equivalent are 10. 03 nGy/hr, 0. 03 mSv/yr, 20. 11 Bq/kg respectively, which fall within UNSCEAR, 2000 threshold. Conclusion: A significant positive relationship exists between the in-situ and evaluated effective dose equivalents (r = 0. 89, p < 0. 05). Radiation dose results indicate insignificant radiological risk, making the study area safe for living and agriculture purposes.

Introduction Foodstuffs are known to contain natural and artificial radionuclides. Determination of radionuclide concentration is of great significance for the protection of human health. The main objective of the present study was the quantification of radionuclides in tea samples, cultivated in Guilan Province in North of Iran. Materials and Methods The activity concentrations of 226Ra, 232Th, 40K, and 137Cs in 18 tea samples were measured, using a gamma spectrometry system. In addition, radium equivalent index (Raeq) and radiation hazard index (HI) were calculated. ANOVA test was used for the statistical analysis of the data Results The concentration of 137Cs was below the minimum detectable activity (MDA). The concentrations of 226Ra and 232Th ranged from < MDA to 0. 042 and < MDA to 0. 037 Bq/kg respectively. The mean concentration of 40K was 410± 15 Bq/kg. Based on the findings, the concentration of 40K was significantly higher than other radionuclides (P<0. 01). Also, the mean Raeq value was estimated at 31. 8± 1. 2 Bq/kg, and HI in the samples ranged from 0. 075 to 0. 093. Conclusion According to the findings, the activity level of radionuclides in tea samples was found to be within the acceptable range and therefore, non-threatening to public health.

Identifying and measuring the radioactivity of airborne particles are necessary and very important to recognizing and estimating the effect of radioactive contamination on human health and the environment. Gamma-ray spectromety is one of the most useful methods for quantitative and qualitative analysis of samples, like air filters. The first and necessary step in performing sample analysis by Gamma-ray spectrometer is to calibrate this equipment which requires appropriate standard sources. The purpose of this research is to design and manufacture a suitable standard source considering filter geometry and its quality control and validation. For this purpose, a circular HEPA air filter with a diameter of 60 mm was used. Gamma-ray spectrometry system (HPGe) was calibrated by mentioned standard source. The results of counting and quality control of the manufactured source showed the accuracy of source manufacturing method. The validation of manufacturing method by Spike method showed an acceptable error of 8%.