Nuclear and Radiation

In connection with conversion of Ghana Research Reactor-1 (GHARR-1) from the use of Highly Enriched Uranium (HEU) fuel to the use of Low Enriched Uranium (LEU) fuel with power upgrading which started in 2006, it is imperative to know how the spent fuel is stored. After the conversion process, the current HEU core will need a Spent Nuclear Fuel (SNF) storage cask to store the HEU fuel. Studies into suitable spent fuel storage cask are ongoing to help solve this challenge. The photon source densities of fission products, actinides and activation products relevant for assessing radiological consequence as well as designing and fabricating Spent Nuclear Fuel storage cask for GHARR-1 using local shielding material has been estimated for its 90.2% HEU fuel. Results showed that the bounding radiological dose due to hypothetical accidents can be evaluated at the end of irradiation (at discharge). Results have also proven key to the selection of shielding materials for the SNF cask.

Studies show that the number of debris in Low Earth Orbit is exponentially growing despite future debris release mitigation measures considered. Especially, an already existing population of small and medium debris is a concrete threat to operational satellites. Ground based DF-laser and space based Nd YAG-laser solutions which can remove at low expense and in a non-destructive way hazardous debris around selected space assets appear as a highly promising answer.

In this paper, light is shed on the Special Relativity hidden conflicts. The first part will point out some of the Special Relativity self-contradictions in relation to its main outcomes; namely the time dilation, length contraction, relativistic velocity addition, relativistic Doppler shift, and the energy-mass equivalence The second part reveals the reasons beyond the Special Relativity inconsistencies, by demonstrating its mathematical formulation misconceptions, and identifying various contradictions in Einstein’s 1905 derivation of the Special Relativity equations.

Groundwater has been identified as the best source of rural water supply because it has eliminated the problem of water borne diseases which have affected communities in the Pru District in the Brong Ahafo Region for some years. An adequate and sustainable source of groundwater can be obtained by geophysical methods which ensure that potable and safe drinking water is available for the entire population. Integrated geophysical methods involving Electromagnetic and Electrical resistivity methods have been carried out to delineate groundwater potential and locate drilling sites for boreholes in the District. The Electromagnetic profiling method was used for reconnaissance survey to identify anomaly conductive spots for further investigation using the Vertical Electrical Sounding (VES) technique. The Schlumberger array was carried out for the VES investigation. Interpretation of the VES data revealed a general pattern of a three layered earth structure, namely topsoil, saturated sandy/ lateritic clay and weathered/ fractured/ fresh basement rocks. The presence of aquifer units included the weathered zones and the fractured basement. These units are found at a depth ranging between 27.0 and 69.5 m.

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.

Radioactivity concentrations of natural radionuclides, namely 226Ra, 232Th and 40K, in fertilized and non-fertilized soils and vegetables from some agricultural areas were investigated using gamma spectrometry in order to assess the radiological implications of the extended use of phosphate fertilizers in agriculture. The mean activity concentrations of 226Ra, 232Th and 40K in the fertilized soils were 23.84 ± 2.52 Bqkg-1, 43.64 ± 2.19 Bqkg-1 and 199.69±3.67 Bqkg-1 respectively. For the non-fertilized soils, mean activity concentrations were found to be 14.01 ± 5.90 Bqkg-1 for 226Ra, 29.40 ± 2.03 Bqkg-1 for 232Th and 120.92 ± 4.67 Bqkg-1 for 40K. The study has shown that fertilized soils contain slightly higher concentrations of the three radionuclides than non-fertilized soils. The measured activity concentrations of the five most frequently utilized agricultural fertilizers showed that the highest levels of 226Ra (139.37±11.15kg-1) and 232Th (47.58±3.81 kg-1) were measured in NPK 151515 and the highest level of 40K (8383.47±6.70) was measured in Super master. It was also found that Sulphate of Ammonia recorded the lowest levels of 226Ra, 232Th and 40K. The average value of 226Raeq was 93.32 Bqkg-1for fertilized soils and 63.30 Bqkg-1 for non- fertilized soil. The calculated mean values of the internal hazard index (HIN) and external hazard index (HEX) for all samples were less than unity. The average absorbed dose rate (D?r) values were 38.79 nGyh-1for fertilized soil and 25.60 nGyh-1for non- fertilized soils. The calculated mean annual effective dose due to ingestion of vegetables by the general public was 0.11 mSv/y for 226Ra, 0.05 mSv/y for 232Th and 0.62 mSv/y for 40 K. The result from the study indicates that radiation exposure from consumption of vegetables from the selected farming communities does not pose significant radiological hazard.

Indoor radon concentration measurements in some dwellings in four districts in Ghana have been monitored between 3months and 1 year using LR-115 type II Cellulose Nitrate films in the bare mode. The annual average indoor radon concentrations vary from 9.40 ±6.30 to 144±93.80 (Bqm?3) in the bedrooms. Annual effective doses were calculated, using ICRP-65 conversion values, and the average annual effective dose varied from 0.25 ± 0.08 to 4.33±0.47 mSv. Radon concentration levels and annual effective doses were found to be within recommended limits.

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.

In this paper we have reported the Stokes Parameters of excited Magnesium atom using non-relativistic (DW) and relativistic distorted wave approximation theories (RDW) at incident electron energies 15 and 45 eV. Good agreement has been found on comparison of both DW and RDW methods with each other and the importance of relativistic effect is also explored.

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.