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Showing papers in "World Journal of Nuclear Science and Technology in 2011"


Journal ArticleDOI
TL;DR: In this paper, the adsorption of strontium from aqueous solutions onto PAN/zeolite composite was studied as a function of the initial stontium concentration, pH of the solution, contact time and temperature.
Abstract: This work reports the adsorption of strontium from aqueous solutions onto PAN/zeolite composite. The strontium adsorption on the composite adsorbent was studied as a function of initial strontium concentration, pH of the solution, contact time and temperature. Adsorption isotherms like Langmuir, Freundlich,Dubinin–Radushkevich (D–R) and Temkin were used to analyze the equilibrium data at the different concentrations.Adsorption process well fitted to Temkin isotherm model. Thermodynamic parameters such as the changes in enthalpy, entropy and Gibbs’ free energy were determined, showing adsorption to be an exothermic and spontaneous process.

50 citations


Journal ArticleDOI
TL;DR: A survey of radioactivity concentration in water supplies used for domestic and industrial purposes in the oil and gas producing communities of Delta State, Nigeria was carried out using a well-calibrated High-Purity Germanium (HPGe) detector system.
Abstract: A survey of radioactivity concentration in water supplies used for domestic and industrial purposes in the oil and gas producing communities of Delta State, Nigeria was carried out using a well-calibrated High-Purity Germanium (HPGe) detector system. The study area was partitioned into ten sections and a total of two samples per partition were collected for analysis. Samples of water from a non-producing area were also collected as control. In all, a total number of forty three samples were collected and analyzed. Each sample was acidified at the rate of 10 ml of 11 M HCl per litre of water to prevent the absorption of radionuclides into the wall of the container and sealed in a properly cleaned container for at least one month so as to attain a state of secular radioactive equilibrium before analysis. The photopeaks observed with reliable regularity belong to the naturally occurring series-decay radionuclide headed by 238U and 232Th, as well as the non-series decay type 40K. The mean specific activity obtained for 40K was 49 ± 15 Bq L–1 with a range of 6 - 177 Bq L–1 while for 238U, the mean specific activity was 3 ± 1 Bq L–1 with a range of 1 - 12 Bq L–1 and the mean specific activity for 232Th was 3 ± 2 Bq L–1 with a range of 2 - 10 Bq L–1 and the total annual effective dose, which vary between 0 - 2 μSv y–1, did not show any significant health impact.

18 citations


Journal ArticleDOI
TL;DR: In this paper, the specific activity concentration and the derived annual effective dose (AED) in three types of vernonia cultivated and consumed within and outside Cameroon were measured by means of a well-calibrated high-purity germanium detector.
Abstract: The specific activity concentration and the derived Annual Effective Dose(AED) in three types of vernonia cultivated and consumed within and outside Cameroon were measured by means of a well-calibrated high-purity germanium detector. Vernonia samples were collected directly from the production farms, oven-dried to a constant mass, crushed, sieved and sealed for at least a month before analysis. The specific activity of 238U in the three types of vernonia ranged from 20 - 50 Bq kg-1 with an average of 42 ± 15 Bq kg-1, 232Th from 9 - 22 Bq kg-1 with an average of 17 ± 7 Bq kg-1 while 40K ranged from 115 - 460 Bq kg-1 with an average of 302 ± 36 Bq kg-1. The average AED for 40K, 238U and 232Th were 0.15, 0.92 and 0.92μSv y-1 respectively. 238U and 232Th show the same trends both for the regional distribution of the radioactivity content and the AED. The discrepancies in our data can be attributed to many factors such as geological formation, foliar deposition, type and age of the plant, etc. Although the results obtained represent only some fractions of the standard limit, but they are within some range obtained in other countries.

18 citations


Journal ArticleDOI
TL;DR: In this paper, the quality factors for protons and helium particles for cell inactivation using linear energy transfer were determined for V79 cells, and the quality has also been investigated as a function for other physical parameters, such as mean free path and effective charge for the particles.
Abstract: Quality factors for protons and helium particles has determined for cell inactivation using linear energy transfer The quality has also been investigated as a function for other physical parameters, such as mean free path and effective charge for protons and helium particles, for a better interpretation to the effectiveness of these charged particles in V79 cells Explanation of quality is clearly illustrated in terms of the average dis-tance of energy deposition events in biological systems

14 citations


Journal ArticleDOI
TL;DR: In this article, the authors presented neutronic calculations for heavy water research reactor core substituting hydride fuel for uranium dioxide fuel, and the required group constants for the CITATION code will be calculated using WIMSD-4 code.
Abstract: This research presents neutronic calculations for heavy water research reactor core substituting hydride fuel for uranium dioxide fuel. The aim of this research is feasibility analysis of reactor utilization with its original design using a new proposed fuel and changing the coolant and moderator circuit to light water. The required group constants for the CITATION code will be calculated using WIMSD-4 code. Neutronic calculations such as multiplication factors, radial and axial power peaking factor and fuel burn-up calculations are carried out by the CITATION code.

11 citations


Journal ArticleDOI
TL;DR: In this article, the total neutron flux of the Ghana Research Reactor-1 (GHARR-1) was measured after a beryllium reflector was added to its shim to compensate for excess reactivity loss.
Abstract: Accurate neutron flux values in irradiation channels of research reactors are very essential to their usage. The total neutron flux of the Ghana Research Reactor-1(GHARR-1) was measured after a beryllium reflector was added to its shim to compensate for excess reactivity loss. The thermal, epithermal and fast neutron fluxes were determined by the method of foil activation. The experimental samples with and without a cadmium cover of 1-mm thickness were irradiated in the isotropic neutron field of the irradiation sites of Ghana Research Reactor-1 facility. The induced activities in the sample were measured by gamma ray spectrometry with a high purity germanium detector. The necessary correction for gamma attenuation, thermal neutrons and resonance neutron self-shielding effects were taken into account during the experimental analysis. By defining cadmium cutoff energy of 0.55eV, Al-0.1% Au wires of negligible thickness were irradiated at 3kW to determine the neutron fluxes of two irradiation channels, outer channel 7 and inner channel 2 whose Neutron Shaping Factor (α) were found to be (0.037 ± 0.001) and (–0.961 ± 0.034). The neutron flux ratios at the inner irradiation site 2 were found to be, (25.308 ± 3.201) for thermal to epithermal neutrons flux, (0.179 ± 0.021) for epithermal to fast neutrons flux and (4.528 ± 0.524) for thermal to fast neutrons flux, in the outer irradiation site 7, the neutron flux ratios were found to be, (40.865 ± 3.622) for thermal to epithermal neutrons flux, (0.286 ± 0.025) for epithermal to fast neutrons flux and (11.680 ± 1.030) for thermal to fast neutrons flux.

9 citations


Journal ArticleDOI
TL;DR: Simulations indicate that it should be possible to utilize the TMFD system for optimal neutron-based interrogation of SNMs, and results of simulations of three active detection techniques utilizing a TM FD system are presented.
Abstract: This paper (constituting Part B) addresses active interrogation for detecting Special Nuclear Materials (SN- Ms) and includes description of the transformational Tensioned Metastable Fluid Detector (TMFD) based method for optimal monitoring. One of the greatest difficulties in detection of SNMs by active interrogation is the task of distinguishing between the probing particles and the secondary particles that indicate the presence of SNMs. The TMFD’s selective insensitivity and γ photon blindness features are advantageous for alleviating this problem. The working principle of the TMFD is discussed along with its applications for security. The experimental work to date involving detection of small quantities of uranium with conventional detectors is discussed along with results of fission neutron detection. Statistically significant detection was achieved within 5 minutes of counting to ascertain and measure conclusive evidence for the presence of a 55g sample of uranium containing 235U. Results of simulations of three active detection techniques utilizing a TMFD system are presented. The process for using the TMFD to discriminate active source particles using timing and energy are described. These simulations indicate that it should be possible to utilize the TMFD system for optimal neutron-based interrogation of SNMs.

5 citations


Journal ArticleDOI
TL;DR: The purpose of this paper is to introduce an aging and life management system for an operating RPV which can be used as a reference of the lifetime extension and it is anticipated that the developed system can be use as an efficient tool for aging andlife estimation of RPV.
Abstract: Reactor pressure vessel (RPV), the only key component that can not be replaced in nuclear power plants (NPPs), is the main barrier against the radioactive leakage The lifetime of NPPs is dependent heavily on the life of RPV, and thus, the aging and life research on a RPV is a key factor in determining the life extension of NPPs The purpose of this paper is to introduce an aging and life management system for an operating RPV which can be used as a reference of the lifetime extension In order to realize the objective, an aging and life management system was developed It is an comprehensive knowledge management system that integrates decentralized information and serves as a valuable data center Based on the storage and management of RPV state information and operation data, this system provides real-time monitoring of important operating parameters, evaluation of irradiation embrittlement, and RPV aging assessment Therefore, it is anticipated that the developed system can be used as an efficient tool for aging and life estimation of RPV

4 citations


Journal ArticleDOI
TL;DR: Improvements in accuracy can be expected from cooperative works with other techniques: indirect methods (urines and faeces) and passive detectors placed correctly on the body can in the case of high levels of contamination can be used to improve the burden assessment.
Abstract: Whole body counting (WBC) benefits from new types of detectors and methodologies. It has found applications in areas such as in medicine, protection of workers and of population. The design of a WBC facility should be tailored to the type of application. Monte Carlo calculations help to improve the reliability of the calibration of a facility, particularly for non-standard measurements (child, etc.), help in optimizing shielding of counting rooms, preventing large systematic errors and lowering detection limits. In vivo counting may be used to evaluate the distribution of radionuclides in organs for metabolic studies with multiple detectors or with a scan of the body. Reduction of detection levels by background reduction is limited. Improved sensitivity can be obtained by adapting the detector type and size to the measured photon energy. The benefit of comparison exercises and training courses are demonstrated. Further improvements in accuracy can be expected from cooperative works with other techniques: indirect methods (urines and faeces) and passive detectors placed correctly on the body can in the case of high levels of contamination can be used to improve the burden assessment.

4 citations


Journal ArticleDOI
TL;DR: In this paper, the delay neutron flux spectrum of the compact core of the Ghana's miniature neutron source reactor (MNSR) was studied using the Monte Carlo method, and 20,484 energy groups combined for all three categories of the energy distribution, thermal, slowing down and fast regions were modeled to create small energy bins.
Abstract: A slightly prompt critical nuclear reactor would increase the neutron flux exponentially at a high rate causing the reactor to become uncontrollable, however due to the delayed neutrons, it is possible to leave the reactor in a subcritical state as far as only prompt neutrons are concerned and to also sustain the chain reaction when it is going to die out. The delay neutron flux spectrum of the compact core of the Ghana’s miniature neutron source reactor (MNSR) was studied using the Monte Carlo method. 20,484 energy groups combined for all three categories of the energy distribution, thermal, slowing down and fast regions were modeled to create small energy bins. The moderator, the inner irradiation channels, the annulus beryllium reflector and the outer irradiation channels were the regions monitored. The delay thermal neutrons recorded its highest flux in the inner irradiation channel with an average flux of (4.0127 0.0076) × 1008 n/cm2?s, followed by the outer irradiation channel with an average flux of (2.4524 0.0049) × 1008 n/cm2?s. The beryllium reflector recorded the lowest flux in the thermal region. These values of the thermal energy range occurred in the energy range (0 – 0.625× 10 – 07) MeV. The inner irradiation channel again recorded the highest average flux of (1.2050 ± 0.0501) × 1007 n/cm2?s at the slowing down region in the energy range (0.821 – 6.94) MeV. The outer irradiation channel recorded the lowest flux in this region. In the fast energy region, (6.96 – 20) MeV, the core, where the moderator is found, the same trend was observed with the inner irradiation channel recording the highest flux at an average flux of (2.0647 ± 0.3260) × 1006 n/cm2?s .The outer irradiation channel recorded the second highest flux while the annulus beryllium reflector recorded very low flux in this region. The final k-effective contribution from only delay neutrons is 0.00834 with the delay neutron fraction being 0.01357 ± 0.00049, hence the Ghana MNSR has good safety inherent feature.

4 citations


Journal ArticleDOI
TL;DR: In this article, the isotopic inventories and corresponding activities of important nuclides for different fuel cycles of a CANDU reactor have been compared and the calculations have been performed using the computer code WIMSD4.
Abstract: In these studies the isotopic inventories and corresponding activities of important nuclides for different fuel cycles of a CANDU reactor have been compared. The calculations have been performed using the computer code WIMSD4. The isotopic inventories and activities have been calculated versus the fuel burn-up for the natural UO2 fuel, 1.2% enriched UO2 fuel and for the 0.45% PuO2-UO2 fuel. It is found that 1.2% enriched uranium fuel has the lowest activity as compared to other two fuel cycles and vice versa for the 0.45% PuO2-UO2 fuel.

Journal ArticleDOI
TL;DR: In this paper, a transformational Tensioned Metastable Fluid Detector (TMFD) based method for passive detection of Special Nuclear Materials (SNMs) as related to nuclear security is described.
Abstract: This paper (constituting Part A) describes the transformational Tensioned Metastable Fluid Detector (TMFD) based method for “passive” detection of Special Nuclear Materials (SNMs) as related to nuclear security. Purdue University is developing novel, multi-purpose tension metastable fluid nuclear particle detectors by which multiple types of nuclear particles can be detected with high (90%+) intrinsic efficiency, spectroscopic capability, directional information, rapid response, large standoff and significant cost-savings compared with state-of-the-art systems. This paper focuses specifically on recent advances in the use of these novel detector systems for neutron spectroscopy. These techniques will then be discussed and evaluated in the context of area monitoring in waste processing applications with a focus on passive monitoring of radioactive source particles from SNMs. The companion paper (Part B) addresses TMFD technology as it pertains to active interrogation.

Journal ArticleDOI
TL;DR: In this article, a stack containing target-detectors assembly was irradiated at SPS-CERN using an optical microscope to collect the data in the form of etched cone heights, from the cone height measurements, total and partial charge changing cross sections of 207Pb projectiles on aluminum target are determined.
Abstract: We investigate 158A GeV 207Pb projectile fragmentation on Al target using CR-39 nuclear track detectors. A stack containing target-detectors assembly was irradiated at SPS-CERN. After chemical etching, detectors were scanned using an optical microscope to collect the data in the form of etched cone heights. From the cone height measurements, total and partial charge changing cross sections of 207Pb projectiles on aluminum target are determined. The results are compared with both relevant published measurements available in the literature and model predictions. Odd-even effect in the formation of the fragments of 158A GeV 207Pb pro-jectiles is observed in a consistent and a clear manner over the observed range of fragments (Z=63-81). This is achieved by using optimized etching and track measurement conditions.