Felix Ameyaw | University of Ghana (original) (raw)

Papers by Felix Ameyaw

Science and Technology of Nuclear Installations

Common cause failures (CCFs) may lead to the simultaneous unavailability or failure of numerous c... more Common cause failures (CCFs) may lead to the simultaneous unavailability or failure of numerous components in the nuclear power plant because of the existence of a shared cause when an initiating event disrupts the normal functioning of nuclear power plants. The presence of common cause failures (intra-unit and inter-unit) can be recognized in a multi-unit probabilistic safety assessment (MUPSA) as a crucial dependency factor that can influence accident scenarios and the core damage frequency (CDF), as CCF may affect the availability and proper operation of mitigating systems. Since such failures are likely to significantly undermine the benefits of the concept of redundancy in nuclear power plant systems, it is necessary to identify the CCFs that contribute to the core damage in a multi-unit site and analyse their overall quantitative magnitude and qualitative proportions. In this study, a twin-unit generic pressurized water reactor (PWR) nuclear plant is modeled using the AIMS-PSA...

Journal of Power and Energy Engineering

A B ST R A C T The purpose of this study was to determine the levels of trace elements in some se... more A B ST R A C T The purpose of this study was to determine the levels of trace elements in some selected fruit juices and carbonated beverages purchased in Accra metropolis, Ghana. The technique used in this study was Instrumental neutron activation analysis (INAA). Fruit juices considered in this study includes pineapple, strawberry, lemon and orange. Some carbonated drinks were also analysed in this analysis. The trace elements considered were Al, Br, Ca, Cl, Mg, Mn, Na, K, Cd, Co, and As. Generally, the trace elements in the fruit juices were found to be more than that of the carbonated beverages. As, Cd, Co and Br were not detected in any of the samples analysed. Also Ca, Mg, Mn were not present in all the carbonated drinks studied. The levels of trace elements in both the fruit juices and carbonated drinks were however within permissible levels.

Radiation absorbed dose data of staff at the Nuclear Reactor Research Centre (NRCC) of Ghana Atom... more Radiation absorbed dose data of staff at the Nuclear Reactor Research Centre (NRCC) of Ghana Atomic Energy Commission, from 2011 to 2015, was analyzed to evaluate the performance of personnel monitoring program prior to the reactor core conversion, and to set baseline criteria for compliance after the core conversion. Personnel radiological deep dose data Hp (10) and surface dose data Hp (0.07) of three radiation workgroups, each of 4 wor-kers were extracted from Thermolumiscent Dosimeters (TLDs). The reactor dose rate data from coolant water was used as control factor influencing radiation absorbed by the staff. The mean dose rate values were respectively, 0.56 mSv and 0.48 mSv for H p (10) and H p (0.07), which were very low compared to the annual occupational limit of 20 mSv/year averaged over any 5-year period set by the International Commission on Radiological Protection. Statistical analyses were performed using Repeated Measure Analysis of Variance, Multivariate Analysis and ...

Science and Technology of Nuclear Installations, 2021

Fault trees (FT) and event trees (ET) are widely used in industry to model and evaluate the relia... more Fault trees (FT) and event trees (ET) are widely used in industry to model and evaluate the reliability of safety systems. This work seeks to analyze and estimate the core damage frequency (CDF) due to flow blockage (FB) and loss of coolant accident (LOCA) due to large rupture of primary circuit pipe with respect to a specific 10 MW Water-Water Research Reactor in Ghana using the FT and ET technique. Using FT, the following reactor safety systems: reactor protection system, primary heat removal system, isolation of the reactor pool, emergency core cooling system (ECCS), natural circulation heat removal, and isolation of the containment were evaluated for their dependability. The probabilistic safety assessment (PSA) Level 1 was conducted using a commercial computational tool, system analysis program for practical coherent reliability assessment (SAPHIRE) 7.0. The frequency of an accident resulting in severe core damage for the internal initiating event was estimated to be 2.51e − 4/...

Annals of Nuclear Energy, 2018

Abstract A key element in the safety of any Nuclear Research Reactor design is the evaluation of ... more Abstract A key element in the safety of any Nuclear Research Reactor design is the evaluation of the reactor's ability to withstand events that could reasonably be postulated to occur and, if unmitigated, could lead to core damage or radionuclides releases to the atmosphere. A first step to ensuring that the reactor design is sufficiently robust to withstand accidents is to identify a comprehensive list of IEs that might lead to core damage or radionuclide releases. This work seeks to present as comprehensive as possible the results obtained from identifying possible important initiating events (IEs) applied in the development of PSA Level-1 study for a 10 MW Water-Water Research Reactor (VVR). The methodology involves the listing approach and the IE screening and grouping methodologies and the focus was on internal IEs due to random failures of components and human errors with full power operational conditions and the reactor core was the radioactivity source. The results provided a set of IEs that were as systematic and as representative as possible, providing confidence to the completeness of PSA study. This study is one of the first few to address comprehensive steps to identify important IEs used in Level-1 PSA study.

Journal of Hazardous, Toxic, and Radioactive Waste, 2016

AbstractRadioactive sources have been in use in Ghana over the last six decades, mainly in medici... more AbstractRadioactive sources have been in use in Ghana over the last six decades, mainly in medicine, agriculture, industry, research, and academic investigations. Radioactive sources declared “disused” by users are required to be transferred to the Centralized Waste Processing and Storage facility of the National Radioactive Waste Management Center (NRWMC) located on the Ghana Atomic Energy Commission (GAEC) site in Kwabenya, a suburb of Accra. The NRWMC is the only national center mandated by regulation to receive and manage all radioactive waste in Ghana. A considerable number of radioactive sources received at the facility since its operation were without the necessary source information such as radionuclide, activity and reference date, identification number, supplier/manufacturer, etc. Sources received with information and those received without the proper information are both required to be properly characterized for the purpose of nuclear material accounting, segregation, pretreatment, conditioning...

Radiation Protection and Environment, 2014

Globally, the cement industry has been identified as one which causes significant particle pollut... more Globally, the cement industry has been identified as one which causes significant particle pollution. In Ghana, environmental research in the neighborhood of the cement industry especially on human health is scanty. In the present work, attempts were made to evaluate the concentration of airborne dust at various distances and directions around the Diamond Cement Factory in the Volta Region of Ghana. The samples of dust were collected on filter papers and later analyzed for the concentration (mg/kg) of 232 Th and 238 U using neutron activation analysis. The principal objective of the study was to generate data intended at assessing the annual effective dose due to 232 Th and 238 U inhalation for both adult and children population living in the vicinity of cement factory. The data generated were supposed to assist in remediation decision making, if required. The study recored a few incidences of higher total dust load concentrations as compared to the permissible limit of 150 μg/m 3 specified by the Ghana Environmental Protection Agency. The calculated mean effective doses were 28.2 ± 1.06 μSv/year and 25.9 ± 0.91 μSv/year for both adult and child, respectively. From the radiological point of view, the study concluded that the people living in the vicinity of the cement factory are not at risk to significant radiological hazards. However, the study indicated the need to have a complete evaluation of the impact of the factory on the environment assessment programs which should include both chemical and radiological toxicity.

Nuclear desalination of seawater has been identified as one of the affordable means of fresh wate... more Nuclear desalination of seawater has been identified as one of the affordable means of fresh water production. However this can only be achieved by the design of energy efficient desalination systems. This study focused on cycle analysis of the cogeneration nuclear power plant. A theoretical model of the Thermo Vapour Compression (TVC) desalination process was also developed and coupled to the cogeneration nuclear power plant. The modeled coupled system was developed on the computer code, NUCDES using FORTRAN language to investigate the effect of design and operating parameters on parameters controlling the cost of producing fresh water from TVC process. The results showed that the performance of the TVC desalination process and the efficiency of the cogeneration nuclear power improve with the motive steam pressure.

In this study, total suspended particulate matter (aerodynamic diameter range between 0.05 and 5 ... more In this study, total suspended particulate matter (aerodynamic diameter range between 0.05 and 5 μm) levels in the vicinity of the Diamond Cement (DIACEM) Factory, Aflao, Ghana were measured and analyzed for As, Cr, Ni and Zn using multi-elemental technique of instrumental neutron-activation analysis. The primary objective of the study was to assess the human health risk of the trace metals exposure for children and adult population in four stratified zones in the study area. From the results, the mean dust level (538.92 μg/m3) around the cement facility deviated completely from regulatory specification (150 μg/m3) indicating massive air pollution in the area. The mean concentration (mg/kg) of trace metals in the area were found in the order of Ni (44.38) >Zn (25.65) > Cr (15.26) >As (2.87). The human-risk assessment study indicated that non-carcinogenic risk was insignificant but the risk of cancer could be probable. Ingestion exposure was the highest level of risk found f...

Journal of Energy

Energy has become the driving force for national infrastructure development, including the socioe... more Energy has become the driving force for national infrastructure development, including the socioeconomic development of every society. Ghana, like many other African countries, formulated developmental policies to attain middle-income status in the medium term. Socioeconomic growth comes with an upsurge in electricity consumption. Ghana seeks to use industrialization to achieve its middle-income target. To achieve this target, there is a need to develop a reliable, sustainable and affordable energy supply in a benign environment. The entry point for Ghana to become a middle-income economy is a cost-effective and reliable electricity supply. Ghana is endowed with fossil fuel, hydro and renewable resources to drive its industrial ambitions, but the indigenous gas fields feeding some thermal plants for electricity production are decreasing and could run out by early 2030 unless new fields are discovered and may also be affected by price volatility. The untapped hydro resources are also...

Energy and Power Engineering, 2013

The worldwide demand for portable water is steadily growing due to population, industrial and agr... more The worldwide demand for portable water is steadily growing due to population, industrial and agricultural growth, the result is water shortages that are already reaching serious proportions in many parts of the world. This is particularly true in Ghana where there is an increasing reliance on bottled water due to shortage of safe, fresh drinking water. Nuclear and conventional co-production of electricity and portable water has been identified as key solution to the perennial water shortages in coastal towns in Ghana. A reliable desalination cost date catering for site-specific condition in Ghana is required for policy makers, planners, consultants, process engineers, plant suppliers and researchers. This present paper is aims comparing the cost of co-production of power and portable water using reverse osmosis (RO) plant coupled with both nuclear and fossil power plant operating under different cycles using the desalination economic evaluation programme (DEEP4.0) developed by the international atomic energy agency (IAEA). The study concentrates on conditions of seawater in Accra, Ghana. Results show that co-production nuclear power plant operating on steam cycle can be the most economic among a number of power-water production options.

Journal of Nuclear Engineering and Radiation Science

Common Cause Failure (CCF) quantification mainly involves the estimation of potential failure of ... more Common Cause Failure (CCF) quantification mainly involves the estimation of potential failure of redundant components of systems in a NPP. The components considered in quantification of CCF parameters include motor operated valves, pumps, safety relief valves, air operated valves, solenoid operated valves, check valves, diesel generators, batteries, inverters, and battery chargers, and circuit breakers. This work presents results on the CCF parameter quantification using check valves and pumps. The systems considered as case studies for the demonstration of the proposed methodology are Auxiliary Feedwater and HPSI systems of PWR. The posterior estimates of alpha factors assuming two 2 different prior distributions (Uniform Dirichlet prior and Jeffrey’s prior) using the Bayesian method was investigated. This analysis is important due to the fact that prior distributions assumed for alpha factors may affect the shape of posterior distribution and the uncertainty of the mean posterior ...

Environmental Research, Engineering and Management

GHARR-1 facility is a miniature neutron source reactor with a rated power of 30 kW. GHARR-1 was c... more GHARR-1 facility is a miniature neutron source reactor with a rated power of 30 kW. GHARR-1 was commissioned on 8 th March, 1995. The facility has been operating using the microcomputer closed loop system (MCCLS) and the control console (CC) for 19 years. Age-related degradation effects in safety-related systems of nuclear reactors are managed to prevent safety margins from eroding below the acceptable limits provided in reactors design. This paper, therefore, provides an update on managing the safety aspects of ageing of structures, systems, and components (SSC) of GHARR-1. Managing the safety aspects of research reactor ageing requires a proactive, systematic, and integrated ageing management approach for the coordination of all activities relating to control, monitoring, and mitigation of ageing degradation of SSC through the life cycle of GHARR-1. This paper outlines the ageing management programme and mitigation practices. Strategies for the ageing management include periodic safety reviews, design features for components and unit replacement, and succession planning. Information sharing with other operating organizations is one of the means considered by GHARR-1 to attain excellence. This paper again concisely reviews and integrates information developed by other ageing management studies and other available information related to understanding and managing age-related degradation effects.

Nuclear Engineering and Design, 2011

Monte Carlo N-Particle (MCNP) code coupled with PLTEMP/ANL code were used to model and simulate t... more Monte Carlo N-Particle (MCNP) code coupled with PLTEMP/ANL code were used to model and simulate the heat transfer problems in the fuel elements assembly of the Ghana Research Reactor-1 (GHARR-1) by solving Boltzmann transport approximation to the heat conduction equation. Coupled neutron radiation-thermal codes were used to determine the spatial variations of thermal energy in the fuel channels, the heat energy distribution in the radial and axial segments of the fuel assembly and the convective heat transfer processes in the entire core of the reactor. The thermal energy at maximum reactivity load of 4 mk, reactor power of 30 kW and inlet system pressure of 101.3 kPa were found to be 8.896 × 10 −16 J for a single fuel pin, and 1.104 × 10 −15 J and 7.376 × 10 −16 J, for the radial and axial sectioning of the core respectively. Using the PLTEMP/ANL V4.0 code and given that the inlet coolant temperature was 30 • C, the maximum outlet coolant temperature was 51 • C. The energy values were obtained using the following thermodynamic parameters as maximum pressure drop of 0.7 MPa and mass flow rate of 0.4 kg/s. Neutronics point kinetics model and Safety Analysis Report used to validate the results confirmed that the heat distribution in the core did not exceed 100 • C. The heat energy profiles based on the data suggested no nucleate boiling at the simulated energies, and since the melting point of U-Al alloy fuel material is 640 • C, the reactor was considered to be inherently safe during normal or steady state operations.

Nuclear Engineering and Design