Muneer Aziz Saleh

Thermoluminescence dosimetry properties and kinetic parameters of lithium potassium borate glass co-doped with titanium and magnesium oxides.

Lithium potassium borate (LKB) glasses co-doped with TiO2 and MgO were prepared using the melt quenching technique. The glasses were cut into transparent chips and exposed to gamma rays of (60)Co to study their thermoluminescence (TL) properties. The TL glow curve of the Ti-doped material featured a single prominent peak at 230 °C. Additional incorporation of MgO as a co-activator enhanced the TL intensity threefold. LKB:Ti,Mg is a low-Z material (Z(eff)=8.89) with slow signal fading. Its radiation sensitivity is 12 times lower that the sensitivity of TLD-100. The dose response is linear at doses up to 10(3) Gy. The trap parameters, such as the kinetics order, activation energy, and frequency factor, which are related to the glow peak, were determined using TolAnal software.

Luminescence characteristics of Li2CO3–K2CO3–H3BO3 glasses co-doped with TiO2/MgO

Understanding the influence of co-dopants in the luminescence enhancement of carbonate glasses is the key issue in dosimetry. A series of borate glasses modified by lithium and potassium carbonate were synthesized by the melt-quenching method. The glass mixture activated with various concentrations of TiO2 and MgO was subjected to various doses of gamma-rays ((60)Co). The amorphous nature of the samples was confirmed by x-ray diffraction (XRD) spectra. The simple glowing curve of the glass doped with TiO2 features a peak at 230°C, whose intensity is maximal at 0.5 mol% of the dopant. The intensity of the glowing curve increases with the concentration of MgO added as a co-dopant up to 0.25 mol%, where it is two times higher than for the material without MgO thermoluminescence properties, including dose response, reproducibility, and fading were studied. The effective atomic number of the material was also determined. Kinetic parameters, such as kinetics order, activation energy, and frequency factor are estimated. The photoluminescence spectra of the titanium-doped glass consist of a prominent peaks at 480 nm when laser excitation at 650 nm is used. A three-fold photoluminescence enhancement and a blue shift of the peak were observed when 0.1% MgO was introduced. In addition, various physical parameters, such as ion concentration, polaron radius and internuclear distances were calculated. The mechanism for the thermoluminescence and photoluminescence enhancements are discussed.

Assessment of health hazard due to natural radioactivity in Kluang District, Johor, Malaysia

The radiation survey of the ambient environment was conducted using two gamma detectors, and the measurement results were used in the computation of the mean external radiation dose rate, mean-weighted dose rate and annual effective dose, which are 144 nGy h−1, 0.891 mSv y−1 and 178 μSv, respectively. A high-purity germanium detector was used to determine the activity concentrations of 232Th, 226Ra and 40K in soil samples. The results of the gamma spectrometry of the soil samples show radioactivity concentration ranges from 19±1 to 405±13 Bq kg−1 with a mean value of 137±5 Bq kg−1 for 232Th, from 21±2 to 268±9 Bq kg−1with a mean value of 78±3 Bq kg−1 for 226Ra and from 23±9 to 1268±58 Bq kg−1 with a mean value of 207±13 Bq kg−1 for 40K. Radium equivalent activity (Raeq) and external hazard index (Hex) were 290 Bq kg−1 and 0.784, respectively, which were safe for the population. The mean lifetime dose and lifetime cancer risk for each person living in the area with average lifetime (70 y) were 12.46 mSv and 7.25×10−4 Sv year, respectively. The results were compared with values given in United Nations Scientific Committee on the Effects of Atomic Radiation 2000.

Thermoluminescence properties of Li2CO3–K2CO3–H3BO3 glass system co-doped with CuO and MgO

The thermoluminescent properties of boric glass modified with lithium and potassium carbonates (LKB) and co-doped with CuO and MgO are reported for the first time. Two techniques are applied to investigate the effect of dopants and co-dopants on the thermal stimulation properties of LKB. The induced TL glow curves of a CuO-doped sample are found to be at 220°C with a single peak. An enhancement of about three times is shown with the increment of 0.1 mol % MgO as a co-dopant impurity. This enhancement may contribute to the ability of magnesium to create extra electron traps and consequently the energy transfer to monovalent Cu(+) ions. LKB:Cu,Mg is low Z material (Zeff=8.55), and observed 15 times less sensitive than LiF: Mg, Ti (TLD-100). The proposed dosemeter showed good linearity in TL dose-response, low fading and excellent reproducibility with a simple glow curve, and thus, can be used in the radiation dosimetry.

Terrestrial gamma radiation and its statistical relation with geological formation in the Mersing district, Johor, Malaysia.

An extensive survey was carried out for gamma dose rates (GDRs) in the Mersing district, Johor, Malaysia. The average value of GDR measured in the district was found to be 140 nGy h(-1), in the range of 40-355 nGy h(-1). The mean weighted dose rate to the population, annual effective dose equivalent, collective effective dose equivalent, lifetime cancer risk were 0.836 mSv y(-1), 0.171 mSv, 1.18 × 10(1) man Sv y(-1) and 6.98 × 10(-4) Sv y, respectively. An isodose map was produced for the district. One way analysis of variance was used to test for differences due to different geological formations present in the Mersing District.

Assessment of potential human health and environmental impacts of a nuclear power plant (NPP) based on atmospheric dispersion modeling

The United States Environmental Protection Agency (US-EPA) short-range atmospheric dispersion model (AERMOD, v. 12345) is a good candidate for the calculation of offsite radiation doses to the general public, and its advanced capability should provide better confidence in the accuracy of offsite public doses assessment. In this paper the AERMOD code has been used to assess the impact of routine and accidental atmospheric radioactive discharges from a new nuclear power plant (NPP) site in Geregu, Nigeria (7˚ 33ˈ N, 6˚ 41ˈ E) on the four major settlements (Ajakuta, Lokoja, Idah and Okene) that lay within the emergency planning zones of the NPP. The code has produced values of the scaling factors for ground level air concentrations and depositions of radionuclides (from the passing plume) over our areas of interest. The scaling factors have been used to assess the potential radiological impact on the offsite human and non-human biota. While the authorities, an integrated approach to the assessment and management of environmental risks from ionizing radiation (D-ERICA) was adopted for the non-human biota. The results of this work indicate that, under normal operations, the NPP does not pose any significant public health and environmental impacts. However, accidental conditions characterized by precipitation will lead to discernible radiological risks within the NPP sites emergency planning zone.

Thermoluminescence responses of photon- and electron-irradiated lithium potassium borate co-doped with Cu+Mg or Ti+Mg

New glasses Li2CO3-K2CO3-H3BO3 (LKB) co-doped with CuO and MgO, or with TiO2 and MgO, were synthesized by the chemical quenching technique. The thermoluminescence (TL) responses of LKB:Cu,Mg and LKB:Ti,Mg irradiated with 6 MV photons or 6 MeV electrons were compared in the dose range 0.5-4.0 Gy. The standard commercial dosimeter LiF:Mg,Ti (TLD-100) was used to calibrate the TL reader and as a reference in comparison of the TL properties of the new materials. The dependence of the responses of the new materials on (60)Co dose is linear in the range of 1-1000 Gy. The TL yields of both of the co-doped glasses and TLD-100 are greater for electron irradiation than for photon irradiation. The TL sensitivity of LKB:Ti,Mg is 1.3 times higher than the sensitivity of LKB:Cu,Mg and 12 times less than the sensitivity of TLD-100. The new TL dosimetric materials have low effective atomic numbers, good linearity of the dose responses, excellent signal reproducibility, and a simple glow curve structure. This combination of properties makes them suitable for radiation dosimetry.

Thermoluminescence properties of lithium magnesium borate glasses system doped with dysprosium oxide

We report the impact of dysprosium (Dy(3+)) dopant and magnesium oxide (MgO) modifier on the thermoluminescent properties of lithium borate (LB) glass via two procedures. The thermoluminescence (TL) glow curves reveal a single prominent peak at 190 °C for 0.5 mol% of Dy(3+). An increase in MgO contents by 10 mol% enhances the TL intensity by a factor of 1.5 times without causing any shift in the maximum temperature. This enhancement is attributed to the occurrence of extra electron traps created via magnesium and the energy transfer to trivalent Dy(3+) ions. Good linearity in the range of 0.01-4 Gy with a linear correlation coefficient of 0.998, fading as low as 21% over a period of 3 months, excellent reproducibility without oven annealing and tissue equivalent effective atomic numbers ~8.71 are achieved. The trap parameters, including geometric factor (μg), activation energy (E) and frequency factor (s) associated with LMB:Dy are also determined. These favorable TL characteristics of prepared glasses may contribute towards the development of Li2O-MgO-B2O3 radiation dosimeters.

First nuclear power in Nigeria: an attempt to address the energy crisis?

This paper attempts to explore to what extent a first Nuclear Power Plant (NPP) will improve the energy situation in Nigeria and investigates the socio-economic impacts of the NPP on the communities where the facilities are to be sited. Other issues that are addressed in this paper include the policy issues, lack of investments in power infrastructure and the security threat owing to incessant domestic militancy or terrorism. The paper then outlines the ways to tackle these problems and concludes that despite the facts that the addition of nuclear power into Nigerias energy mix will help in curtailing the countrys energy crisis, it also poses some challenges to the country that the policy and decision-makers must take into consideration right from the preliminary stages of the programme.

Dosimetric Characteristics of a LKB:Cu,Mg Solid Thermoluminescence Detector *

We present the main thermoluminescence characteristics of a newly borate glass dosimeter modified with lithium and potassium carbonate (LKB) and co-doped with CuO and MgO. An enhancement of about three times has been shown with the increment of 0.1mol% MgO as a co-dopant impurity. The effects of dose linearity, storage capacity, effective atomic number and energy dose response are studied. The proposed dosimeter shows a simple glow curve, good linearity up to 103 Gy, close effective atomic number and photon energy independence. The current results suggest using the proposed dosimeter in different dosimetric applications.