Nuclear and Radiation

Pressure dependent exciton binding energy in a Cd0.8Zn0.2Te/ZnTe strained quantum dot is investigated with the geometrical confinement within the single band effective mass approximation. The interband transition energy as functions of dot radius and the hydrostatic pressure is brought out. Computations are carried out using variational formulism. The pressure induced oscillator strength and the nonlinear optical rectification coefficient of an exciton in a Cd0.8Zn0.2Te/ZnTe quantum dot are studied using matrix method. Our results show that the exciton binding energy, interband emission energy and the nonlinear optical rectification coefficient are strongly dependent on the geometrical confinement and the applied hydrostatic pressure values.

As part of the nuclear power project envisaged during the period of the first republic, attempts have been made to prospect for uranium as raw material for the nuclear reactor. The Biakpa area in the Volta region had been known by the indigenes to be a potential source of this raw material. A field survey had been carried out using a Fieldspec radiation survey meter and the uranium content of some rock samples taken from the area has been determined. The uranium content determined by comparison with an IAEA uranium standard S-13 lot 370 using the track etch technique gave a mean value of 0.018%. The dose rate obtained during the survey ranged from 1.22 - 2.25 µSv/h.

The world energy demand is on the increase allowing many countries to find a viable solution to this quandary. Many of such countries are adopting a way to deal with such crisis by considering other conservative means of source of energy. One of such country having difficult to generate enough energy for its economic growth is Ghana. Currently Ghana’s total installed electricity generation capacity stands at 1810MW, with her population estimated to be 24.4 million, based on the 2010 census. Therefore, there is the need for a radical change in energy mix to propel the country’s economic growth. For a brighter future, the country must explore unconditional means to secure cheap and reliable energy resource to satiate the desire of future industrial accomplishments. In this regard, nuclear energy is a descent choice without compromising environmental quality. Given that nuclear power is an important choice in the face of the threat of climate change, the public’s perceptions need to be changed at any cost considering the catastrophic accident at Japan’s Fukushima Daiichi Nuclear Power Plant in March 2011. This paper addresses subjective uncertainty on health effect in hypothetical release using accident analysis code MACCS2 to estimate TEDE (total effective dose equivalent) for postulated accident scenario. The code is for preliminary work on the proposed AP1000 MW(e) NPP at the proposed site, Volta Point Unit 1 in Akosombo, Ghana.

The collimator is the most important part in the installation of the Prompt Gamma Activation Analysis (PGAA). This collimator will be installed around the lateral Channel of the Moroccan TRIGA MARK II research reactor. The main purpose of this work is using the Monte Carlo simulation via the MCNP5 code to design the new collimator of the prompt gammas installation, to determine the optimal thickness of the bismuth (Bi) filter for gamma radiation. The obtained results of the collimator design and its filter are analyzed and discussed.

Intracavitary brachytherapy is a procedure in which radioactive sources are placed in the body cavities close to or inside the target volume to deliver radiation at short distances. In this mode of treatment, high radiation dose can be delivered to the tumour volume with rapid dose fall-off into the surrounding normal tissues. In brachytherapy, the dosimetry in biological tissues is a complex process. Dosimetric parameters such as the dose to critical organs and the total dose to the reference points as in the case of Manchester system are critical for patients undergoing intracavitary brachytherapy treatment. In this study, the finite element method has been utilized to solve Boltzmann Transport Equation (BTE) to determine the distribution of angular photon fluxes at various positions in the cervix of cancer patients and the dose distribution calculated for the organs of interest. Results from the study indicate doses to the rectum and the bladder to be in the range of 21.5-90.10cGy and 25.60-110.02cGy respectively for stage I to stage IV cancer patients. Comparison of the results from this model with data from published articles and dose prescriptions from the treatment planning system of the Radiotherapy Centre of the Komfo Anokye Teaching Hospital in Ghana for different cancer stages indicate good agreement.

The study of the physical process of a pulsed laser interacting with human brain tissue is important to identify the energy transport of photons in a strongly diffused zone. The purpose of this article is to describe by a numerical simulation method (Monte Carlo), the light bundle formed by the source-detector pair by scanning a portion of the volume of diseased tissues. In the present simulation, we use the experimental results: the absorption and scattering coefficients respectively ma and ms. We follow the paths of a random walker and we plot for each event as a first step, the relative fluence rate, the reflectance and the transmittance of the signal in terms of respectively depths of penetration and the times expressed in (ps) using a cylindrical geometry. The second step is to study the distribution of the photons of the recorded at different positions, dependent primarily on the ultra-short pulsed laser source in femtosecond wavelength of 800nm. We consider the spherical coordinates (R,q,j) and time t. Thereafter, we compare these results with those calculated with the Cartesian coordinates (x,y,z).

Water is the essential element in creating and sustaining conditions for human life Cell of the organism, and the medium in which we live. Water is one of the most important natural elements in our cart Ground is the secret of life, and is one of the most important components of living matter. Water accounts for 63% of the human body weight (Average) and human muscles contain about 83% of it. The human body needs about 5.2 liters Daily of water, and gets this amount of food and drink. Water plays a key role in the chemical processes in the body, and rid of waste, and contributes to the regulation of body temperature process Sweating. Due to the importance of drinking water in the preservation of life on the one hand, water is exposed to pollution by Many pollutants, including microorganisms, minerals, organic substances and radioactive materials, on the other hand Which called for the issuance of standards for the acceptance of drinking water, whether global or local standards. The focus will be on this study on the radiological side [1]. Although Kuwait does not have natural drinking water resources such as wells or rivers, most bottled water companies are directed to seawater in desalination, or resort to drill coastal beach wells. The coastal beach wells, are wells drilled near the coast of sea at depths of up to 50 meters, and are extracted from it salty sea water, but it is free of pollutants and impurities, or can be taken directly from the sea and thus work is a comprehensive desalination of water and adding Minerals such as magnesium and calcium, in addition to ensuring that it is free of any bacteria or viruses and detect its radioactive contamination or ensure that the concentration of natural radionuclides are not exceeded the international limit in this drinking water, after that water treatment and the addition of ozone gas for sterilization, then the final stage is manufacturing conservation bottles and bottling water in different sizes and processing for sale to the consumers. In this study, the concentration of radon gas in different samples of bottled mineral drinking water companies was measured in State of Kuwait. Concentration of (222Rn) in Bottled Mineral drinking water varies from 1.02 Bq/L to 6.05 Bq/L with the average value of 2.97±1.44 Bq/L. From these results it can be concluded that the majority of drinking water is safe to use from the stand point of concentration of radon in them. Mean values of effective dose per liter and annual effective dose from radon ingested with drinking water for an individual consumer are 29.72 nSv/L and 21.69 ?Sv/y, respectively. So, the level of Radon concentration in Kuwaiti bottled mineral drinking water is below the permissible limits for health purposes to drink.

The averages concentrations of 238U, 232Th and 40K measured in the samples collected in this study are 130.6±38.7 BqKg-1, 137.9±39.7 BqKg-1 and 1120.1±245.2 BqKg-1 respectively. The absorbed dose rate in air at a height of 1m above the ground surface was estimated. The calculated radiation absorbed dose ranges from 95.4±3.2 nGyh-1 to 300.4±5.5nGyh-1 with an average of 193.2±44.5 nGyh-1 .The effective dose rates were calculated for human exposure to the gamma radiations and were found to be in the range (0.23±0.01- 0.74±0.02) mSv y-1, which is below the ICRP limit of 1 mSv y-1 for members of the general public.

This research was carried out to monitoring natural radioactivity level in rock samples were taken from Northern Nuba Mountain, Dallanj region - South Kordofan State. Gamma ray spectroscopy technique was used to evaluate radioactivity level to establish background radiation level. Measured activity concentrations of radionuclides 226Ra,232Th and 40K ,absorbed dose and annual effective dose were found 23.56±2.11, 29.57±4.33 and 330.58±37.06 Bqkg-1 and 33.34±3.39 nGyh-1 and 40.92±4.16 µSvy-1 , respectively. The obtained data shown that values are far below than reported global data. Estimation of the relative contribution of the 226Ra, 232Th and 40K to the overall absorbed dose in air discovered that the main contribution comes from 232Th 53.57 %.

The concentration of radon has been investigated in a university campus in Nigeria to determine the health risk of the workers in the community. Seventy- eight offices were statistically selected for measurement from all the Colleges. Measurements were performed using a passive radon dosimeters comprising (CR-39) solid state nuclear track detector, for a period of six months. The detectors were chemically etched with 6.25 M solution of NaOH at 70oC for 3 hours. The track were manually counted with microscope coupled with charged coupled digital (CCD) camera. Radon concentrations were statically determined. The mean radon concentration and the effective dose obtained in this work were 18.8 Bq m-3 and 0.02 mSv y-1 respectively. The mean value for excess lung cancer risk was estimated to be 0.08 (MPY)-1. When compared with published data and international references, the results obtained in the current study were found to be within the safe limits. Our study also revealed that radon concentrations tend to be higher on the ground floor and reduced with height due air dilution.