Energy Security

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  • Publication
    Publication
    Simulation of 16O (n, p) 16N reaction rate and nitrogen-16 inventory in a high performance light water reactor with one pass core
    (Elsevier, 2014-12) Kebwaro, Jeremiah Monari; Zhao, Yaolin; He, Chaohui
    The rate of activation of the isotope 16O to 16N in a typical HPLWR one pass concept was calculated using MCNP code. A mathematical model was used to track the inventory of the radioisotope 16N in a unit mass of coolant traversing the system. The water leaving the moderator channels has the highest activity in the circuit, but due to interaction with fresh coolant at the lower plenum, the activity is downscaled. The calculated core exit activity is higher than values reported in literature for commercial boiling water reactors.
  • Publication
    Publication
    Evaluation of candidate materials for SCWR turbine and balance of plant shielding
    (Elsevier, 2014-12-13) Kebwaro, Jeremiah Monari; Zhao, Yaolin; He, Chaohui
    Since the coolant leaving the SCWR core contains an assortment of radioisotopes, it is necessary to identify appropriate materials for shielding ex-core components. Photon attenuation characteristics, photo-neutron production capacity and cost effectiveness of candidate materials were investigated in this study. WinXcom computer code was used for attenuation studies while other properties were surveyed in literature. High Z materials (lead and tungsten) show excellent gamma attenuation properties however they are expensive and could be vulnerable to photo-neutron production if used for shielding turbines or the pressure vessel exit steam-line. Barite concrete which is a moderate attenuator could also be susceptible to photo-neutron production if used for shielding components with high Nitrogen-16 activity. Heavy concretes with iron aggregates on the other hand show fair attenuation and are not susceptible to photo-neutron production in the energy range of photons released from reactor water. In terms of cost, concretes are cheaper and easy to fabricate compared to high Z materials especially when a shield of intricate shape is required. Depending on the available space for the shield, heavy concretes would be the most appropriate materials for shielding the SCWR turbine and balance of plant. However in case of space limitation, their attenuation capacity can be enhanced by introducing high Z materials in reasonable proportions.
  • Publication
    Publication
    Investigation of photoneutron and capture gamma-ray production in Pb and W under irradiation from 16N decay radiation
    (Elsevier, 2015-09-01) Kebwaro, Jeremiah Monari; Zhao, Yaolin; He, Chaohui
    Lead and tungsten are potential alternative materials for shielding reactor ex-core components with high 16N activity when available space limits application of concrete. Since the two materials are vulnerable to photonuclear reactions, the nature and intensity of the secondary radiation resulting from (γ,n) and (n,γ) reactions when 16N decay radiation interact with these materials need to be well known for effective shielding design. In this study the MCNP code was used to calculate the photoneutron and capture gamma-ray spectra in the two materials when irradiated by 16N decay radiation. It was observed that some of the photoneutrons generated in the two materials lie in the low-energy range which is considered optimum for (n,γ) reactions. Lead is more transparent to the photoneutrons when compared to tungsten. The calculations also revealed that the bremsstrahlung generated by the beta spectrum was not sufficient to trigger any additional photoneutrons. Both energetic and less energetic capture gamma-rays are observed when photoneutrons interact with nuclei of the two materials. Depending on the strength of the 16N source term, the secondary radiation could affect the effectiveness of the shield and need to be considered during design.
  • Publication
    Publication
    Status of Biomass Derived Carbon Materials for Supercapacitor Application
    (Hindawi Publishing Corporation, 2017-01-31) Enock, Talam Kibona; King’ondu, Cecil K.; Pogrebnoi, Alexander; Jande, Yusufu Abeid Chande
    Environmental concerns and energy security uncertainties associated with fossil fuels have driven the world to shift to renewable energy sources. However, most renewable energy sources with exception of hydropower are intermittent in nature and thus need storage systems. Amongst various storage systems, supercapacitors are the promising candidates for energy storage not only in renewable energies but also in hybrid vehicles and portable devices due to their high power density. Supercapacitor electrodes are almost invariably made of carbon derived from biomass. Several reviews had been focused on general carbon materials for supercapacitor electrode. This review is focused on understanding the extent to which different types of biomasses have been used as porous carbon materials for supercapacitor electrodes. It also details hydrothermal microwave assisted, ionothermal, and molten salts carbonization as techniques of synthesizing activated carbon from biomasses as well as their characteristics and their impacts on electrochemical performance.
  • Publication
    Publication
    Security and Stability Aspects of Multi Objective Dynamic Economic Dispatch with Renewable Energy and HVDC Transmission Lines
    (Scientific Research Publishing, 2018-06) Musau, Moses Peter
    Renewable sources of energy are being integrated into the power grids due to their economic and environmental merits as compared with the traditional fossil-fuel-fired power generation. However, their significant penetration demands a thorough research in terms of system reliability, that is, security and stability. In this paper, Security Constrained Multi Objective Dynamic Economic Dispatch (SCMODED) problem considering cubic thermal cubic cost function, wind, solar penetration, cubic transmission power losses and cubic emissions cost function as objectives is first formulated. Both HVDC and HVAC lines are included in their formulation. Various approaches like probabilistic load flow (PLF), scenario based method, participation factors and Harmony Search algorithm etc. are employed in the solution process. Security and stability effects of renewable energy (RE) penetration are investigated and analyzed. The simulated results reveal that RE penetration leads to reduced cost and emissions and increased security concerns. Further, there is increased power system instability and hence increased load shedding so as to help the power system attain steady state stability. Inclusion of HVDC lines facilitates rapid and fast control to increase the transient stability limit by the action of the converter ignition angle (CIA) and converter extinction angle (CEA).
  • Publication
    Publication
    Effectiveness Of Energy Sector Quality Management Systems In Response To Electrical Fire Disaster In Kisumu County, Kenya
    (International Journal of Scientific and Research Publications, 2020-11) Odhiambo, Elijah; F., Hassero,
    Globally, utility power transmission and distribution systems are described along with their observed vulnerabilities to natural and man-made hazards. At national level, approximately 40% of the load in the Western region is supplied via 33/0.433 kV secondary distribution transformers. This contributes to transformer overload strain thus contributing to electrical fire disasters and outages. Kisumu substations are overloaded in the existing system under peak load conditions due to low thermal rating of conductors as a result of inadequate sizing. Several line sections feeding a large proportion of the load are of conductor type 25mm2 ASCR causing an effective bottleneck leading to power outages and electric fire disasters. Due to these, the study sought to assess the effectiveness of energy sectors quality management systems in response to electrical fire disaster in Kisumu County. Cross-functional management model and Crosby Theory of Quality theories guided the study. A descriptive research design was used in the study. Sample size of the study was selected using purposive, census and stratified random sampling from the energy sectors; Kenya Power and Lighting Company, Kenya Electricity Transmission Company, Kenya Energy Generating Company and customers connected to electricity grid. The structured questionnaires, interviews guides and observation methods were used to collect data. Quantitative data was analyzed using descriptive statistics while qualitative data responses using thermalized and frequencies. Organizations have not ensured ISO certification requirements in their management systems. That organizations quality management systems were less effective in relation to electric disasters response. The paper recommends that all organization should implement ISOcertification requirements on their management systems. Effect their systems through assistance from other organizations with the same role for effective electric disaster management. Index Terms- Disaster Management Systems, Electric Disaster and Quality Management System