Thermo-Economic Assessment of Advanced, High-Temperature CANDU Reactors

2002 ◽  
Author(s):  
Norman J. Spinks ◽  
Nikos Pontikakis ◽  
Romney B. Duffey
Keyword(s):  
Economic Assessment ◽  
Operating Conditions ◽  
Thermodynamic Efficiency ◽  
Candu Reactors ◽  
Reactor Coolant ◽  
Resource Sustainability ◽  
Temperature Regimes ◽  
Economic Analyses ◽  
Significant Cost Reduction ◽  
Direct Cycle

Research underway on the advanced CANDU examines new, innovative, reactor concepts with the aim of significant cost reduction and resource sustainability through improved thermodynamic efficiency and plant simplification. The so-called CANDU-X concept retains the key elements of the current CANDU designs, including heavy-water moderator that provides a passive heat sink and horizontal pressure tubes. Improvement in thermodynamic efficiency is sought via substantial increases in both pressure and temperature of the reactor coolant. Following on from the new Next Generation (NG) CANDU, which is ready for markets in 2005 and beyond, the reactor coolant is chosen to be light water but at supercritical operating conditions. Two different temperature regimes are being studied, Mark 1 and Mark 2, based respectively on continued use of zirconium or on stainless-steel-based fuel cladding. Three distinct cycle options have been proposed for Mark 1: the High-Pressure Steam Generator (HPSG) cycle, the Dual cycle, and the Direct cycle. For Mark 2, the focus is on simplification via a Direct cycle. This paper presents comparative thermo-economic assessments of the CANDU-X cycle options, with the ultimate goal of ascertaining which particular cycle option is the best overall in terms of thermodynamics and economics. A similar assessment was already performed for the NG CANDU. The economic analyses entail obtaining cost estimates of major plant components, such as heat exchangers, turbines and pumps.

Thermo-economic Assessment, and Multi-objective Optimization of an Innovatively Designed District Cooling System in Saudi Arabia

2021 ◽  
pp. 1-29
Author(s):  
Ali Alsagri
Keyword(s):  
Saudi Arabia ◽  
Waste Heat ◽  
Cooling System ◽  
Economic Assessment ◽  
Optimization Techniques ◽  
Operating Conditions ◽  
Peak Shaving ◽  
Assessment Index ◽  
Economic Analyses

Abstract The experience of leading countries in distributed energy systems (e.g., Scandinavian countries) shows that district cooling systems are highly beneficial techno-economic-environmentally by facilitating the use of waste heat resources, solar energy, etc., for cold supply at large scales. This study proposes the optimal development of a novel district cooling design utilizing the exhaust waste heat of an energy plant in a case study in Saudi Arabia. The optimal configuration of the hybrid system, the sizing of its components, and operating conditions of them are found using multiobjective optimization techniques based on the genetic algorithm method and a creative performance assessment index. Then, the feasibility of this optimized proposal is investigated through comprehensive thermodynamic and economic analyses. The results show that a district cooling system can surely cope with the harsh climate condition of the case study and provide the required interior comfort conditions. The energy and exergy efficiencies of the system can be as high as 62% and 53% using an absorption chiller utilizing a power plant's waste heat along with a storage tank for peak shaving. The levelized cost of cooling of the system can be 28 USD/MWh, by which the payback period will be only 8 years.

scholarly journals Techno-Economic Assessment of Coal-Fired Power Unit Decarbonization Retrofit with KP-FHR Small Modular Reactors

Energies ◽  
2021 ◽  
Vol 14 (9) ◽  
pp. 2557
Author(s):  
Łukasz Bartela ◽  
Paweł Gładysz ◽  
Charalampos Andreades ◽  
Staffan Qvist ◽  
Janusz Zdeb
Keyword(s):  
Net Present Value ◽  
Economic Assessment ◽  
Plant Design ◽  
Term Operation ◽  
Small Modular Reactors ◽  
Greenfield Investments ◽  
Unit Design ◽  
The Difference ◽  
Economic Analyses ◽  
The Eu

The near and mid-term future of the existing Polish coal-fired power fleet is uncertain. The longer-term operation of unabated coal power is incompatible with climate policy and is economically challenging because of the increasing price of CO2 emission allowances in the EU. The results of the techno-economic analysis presented in this paper indicate that the retrofit of existing coal-fired units, by means of replacing coal-fired boilers with small modular reactors, may be an interesting option for the Polish energy sector. It has been shown that the retrofit can reduce the costs in relation to greenfield investments by as much as 35%. This analysis focuses on the repowering of a 460 MW supercritical coal-fired unit based on the Łagisza power plant design with high temperature small modular nuclear reactors based on the 320 MWth unit design by Kairos Power. The technical analyses did not show any major difficulties in integrating. The economic analyses show that the proposed retrofits can be economically justified, and, in this respect, they are more advantageous than greenfield investments. For the base economic scenario, the difference in NPV (Net Present Value) is more favorable for the retrofit by 556.9 M€ and the discounted payback period for this pathway is 10 years.

scholarly journals Experimental Investigation and Modeling of Inertance Tubes

2005 ◽  
Vol 127 (5) ◽  
pp. 1029-1037 ◽  
Author(s):  
L. O. Schunk ◽  
G. F. Nellis ◽  
J. M. Pfotenhauer
Keyword(s):  
Mass Flow Rate ◽  
Mass Flow ◽  
Flow Rate ◽  
Acoustic Power ◽  
Operating Conditions ◽  
Thermodynamic Efficiency ◽  
Pulse Tube ◽  
Design Charts ◽  
Wide Range ◽  
Pulse Tube Refrigerators

Growing interest in larger scale pulse tubes has focused attention on optimizing their thermodynamic efficiency. For Stirling-type pulse tubes, the performance is governed by the phase difference between the pressure and mass flow, a characteristic that can be conveniently adjusted through the use of inertance tubes. In this paper we present a model in which the inertance tube is divided into a large number of increments; each increment is represented by a resistance, compliance, and inertance. This model can include local variations along the inertance tube and is capable of predicting pressure, mass flow rate, and the phase between these quantities at any location in the inertance tube as well as in the attached reservoir. The model is verified through careful comparison with those quantities that can be easily and reliably measured; these include the pressure variations along the length of the inertance tube and the mass flow rate into the reservoir. These experimental quantities are shown to be in good agreement with the model’s predictions over a wide range of operating conditions. Design charts are subsequently generated using the model and are presented for various operating conditions in order to facilitate the design of inertance tubes for pulse tube refrigerators. These design charts enable the pulse tube designer to select an inertance tube geometry that achieves a desired phase shift for a given level of acoustic power.

Empirical Model of Operating Temperature and Pressure Effect towards Pure and Binary O2/ N2 Gas Permeability in Polysulfone Membrane

2018 ◽  
Vol 777 ◽  
pp. 238-244
Author(s):  
Serene Sow Mun Lock ◽  
Kok Keong Lau ◽  
Irene Sow Mei Lock ◽  
Azmi Mohd Shariff ◽  
Yin Fong Yeong ◽  
...  
Keyword(s):  
Empirical Model ◽  
Membrane Separation ◽  
Gas Permeability ◽  
Economic Assessment ◽  
Operating Conditions ◽  
Effect Of Temperature ◽  
Polysulfone Membrane ◽  
Wide Range ◽  
Temperature And Pressure ◽  
Membrane Permeance

Oxygen (O2) enriched air combustion via adaption of polymeric membranes has been proposed to be a feasible alternative to increase combustion proficiency while minimizing the emission of greenhouse gases into the atmosphere. Nonetheless, majority of techno-economic assessment on the O2 enriched combustion evolving membrane separation process are confined to assumption of constant membrane permeance. In reality, it is well known that membrane permeance is highly dependent upon the temperature and pressure to which it is operated. Therefore, in this work, an empirical model, which includes the effect of temperature and pressure to permeance, has been evaluated based on own experimental work using polysulfone membrane. The empirical model has been further validated with published experimental results. It is found that the model is able to provide an excellent characterization of the membrane permeance across a wide range of operating conditions for both pure and binary gas with determination coefficient of minimally 0.99.

scholarly journals Design and Thermo-Economic Comparisons of an Absorption Air Conditioning System Based on Parabolic Trough and Evacuated Tube Solar Collectors

Energies ◽  
2020 ◽  
Vol 13 (12) ◽  
pp. 3198 ◽  
Author(s):  
Adil Al-Falahi ◽  
Falah Alobaid ◽  
Bernd Epple
Keyword(s):  
Air Conditioning ◽  
Thermal Power ◽  
Lithium Bromide ◽  
Operating Conditions ◽  
Coefficient Of Performance ◽  
Parabolic Trough ◽  
Solar Absorption ◽  
Pumping System ◽  
Economic Analyses ◽  
Evacuated Tube

Solar absorption cycles for air conditioning systems have recently attracted much attention. They have some important advantages that aid in reducing greenhouse gas emissions. In this work, design and thermo-economic analyses are presented in order to compare between two different collector types (parabolic trough and evacuated tube) by water–lithium bromide absorption systems, and to select the best operating conditions. Generally, the system consists of three major parts. The first part is the solar field for thermal power conversion. The second part is the intermediate cycle, which contains a flashing tank and pumping system. The third part is the water lithium bromide absorption chiller. A case study for a sports arena with 700–800 kW total cooling load is also presented. Results reveal that a parabolic trough collector combined with H2O–LiBr (PTC/H2O–LiBr) gives lower design aspects and minimum rates of hourly costs (USD 5.2/h), while ETC/H2O–LiBr configuration give USD 5.6/h. The H2O–LiBr thermo-economic product cost is USD 0.14/GJ. The cycle coefficient of performance COP was in the range of 0.5 to 0.9.

Enhancement of Pressurizer Safety Valve Operability by Seating Design Improvement

1995 ◽  
Vol 117 (3) ◽  
pp. 279-282
Author(s):  
N. T. Moisidis ◽  
M. D. Ratiu
Keyword(s):  
Safety Valve ◽  
Operating Conditions ◽  
Maintenance Costs ◽  
Design Improvement ◽  
Reactor Coolant ◽  
Coolant System

Operating conditions specific to pressurizer safety valves (PSVs) have led to numerous problems and have caused industry and NRC concerns regarding the adequacy of spring-loaded self-actuated safety valves for reactor coolant system (RCS) overpressure protection. Specific concerns are: setpoint drift, spurious actuations, and leakage. Based on testing and valve construction analysis of a Crosby model 6M6 PSV (Moisidis and Ratiu, 1992), it was established that the primary contributor to the valve problems is a susceptibility to weak seating. To eliminate spring instability, a new spring washer was designed, which guides the spring and precludes its rotation from the “reference” installed position (Figs. 6 and 7). Results of tests performed on a prototype PSV equipped with the modified upper spring washer has shown significant improvements in valve operability and a consistent setpoint reproducibility to less than ±1 percent of the PSV setpoint (testing of baseline, unmodified valve, resulted in a setpoint drift of ±2 percent). Enhanced valve operability will result in a significant decrease in operating and maintenance costs associated with valve maintenance and testing. In addition, the enhanced setpoint reproducibility will allow the development of a nitrogen to steam correlation for future in-house PSV testing which will result in further reductions in costs associated with valve testing.

Achieving Resource Sustainability in China Through the Thorium Fuel Cycle in the Candu Reactor

2010 ◽  
Author(s):  
Peter G. Boczar ◽  
Bronwyn Hyland ◽  
Keith Bradley ◽  
Sermet Kuran
Keyword(s):  
Fuel Cycle ◽  
Close Approach ◽  
Natural Uranium ◽  
Fissile Material ◽  
Energy Potential ◽  
Candu Reactors ◽  
Fuel Cycles ◽  
Resource Sustainability ◽  
Enriched Uranium

The CANDU® reactor is the most resource-efficient reactor commercially available. The features that enable the CANDU reactor to utilize natural uranium facilitate the use of a wide variety of thorium fuel cycles. In the short term, the initial fissile material would be provided in a “mixed bundle”, in which low-enriched uranium (LEU) would comprise the outer two rings of a CANFLEX® bundle, with ThO2 in the central 8 elements. This cycle is economical, both in terms of fuel utilization and fuel cycle costs. The medium term strategy would be defined by the availability of plutonium and recovered uranium from reprocessed used LWR fuel. The plutonium could be used in Pu/Th bundles in the CANDU reactor, further increasing the energy derived from the thorium. Recovered uranium could also be effectively utilized in CANDU reactors. In the long term, the full energy potential from thorium could be realized through the recycle of the U-233 (and thorium) in the used CANDU fuel. Plutonium would only be required to top up the fissile content to achieve the desired burnup. Further improvements to the CANDU neutron economy could make possible a very close approach to the Self-Sufficient Equilibrium Thorium (SSET) cycle with a conversion ratio of unity, which would be completely self-sufficient in fissile material (recycled U-233).

scholarly journals Adaptation of activated sludge with anammox to low temperatures

2020 ◽  
Vol 207 ◽  
pp. 01026
Author(s):  
Igor Gulshin ◽  
Nikolay Makisha
Keyword(s):  
Activated Sludge ◽  
Structural Changes ◽  
Essential Element ◽  
Ammonium Nitrogen ◽  
Operating Conditions ◽  
Anammox Bacteria ◽  
Stable Operation ◽  
Additional Increase ◽  
Temperature Regimes ◽  
Lower Temperature

The article presents the results of evaluating the ability of activated sludge, saturated with anammox bacteria, to adapt to mesophilic and lower temperature operating conditions. As the main temperature regimes, temperatures of 30, 25, 15, and 13°C were selected. The system has demonstrated stable operation at temperatures about 15°C with the highest degree of purification for ammonium nitrogen - 0.33 mg/L. At the same time, the concentration of nitrites reached 0.07 mg/L taking into account forced nitration. An additional increase in the efficiency of the system requires structural changes in the adopted technological scheme of the bioreactor, however, the introduction of an internal system of recirculation of attached biomass (with load) inside the anammox compartment is considered as an essential element of the system that ensures stability.

scholarly journals Effectiveness of arrangement of the long cargo transportation on the fi tting platforms with different length of freight storage

2019 ◽  
Vol 78 (4) ◽  
pp. 203-209
Author(s):  
S. V. Mozgrin ◽  
G. E. Pisarevskiy
Keyword(s):  
Economic Effect ◽  
Economic Assessment ◽  
Operating Conditions ◽  
Rolling Stock ◽  
Rail Transportation ◽  
Technological Solution ◽  
Specific Data ◽  
Transportation Process ◽  
Cargo Transportation ◽  
Calculation Unit

Fitting platforms of variable freight storage lengths are used for transportation of rails and other cargo up to 25 m long. The use of innovative fixation for transportation on the fitting platforms contributes to enlargement of the range of cargo transported on such rolling stock and establishes conditions for safe transportation of such cargo.To evaluate the effectiveness of the arrangement of long cargo transportation on the fitting platform, this study examines two 25 m long rail transportation options. The transportation option involving two coupled 14.62 m platforms, when the cargo is fixed on the coupled platforms with the standard method is the basic option. The new option involves transportation of the 25 m long rails using 80-feet fitting platforms 25.62 m long at the coupling axes and multiway fi xation sets. A calendar year is assumed as the estimate period. The transported volume is assumed equal for each option, under considering the operating conditions of the calculation unit — one coupling of universal platform (or one 80-feet fitting platform), reducing the financial results to a ton of transported cargo. The value of the annual economic effect for the freight owner (Eyearown) is determined as the change of the freight owner’s expenses due to usage of the new option relative to the basic transportation option.The economic assessment of the transportation is performed considering the interests of each member of the transportation process and tested based on specific data. The results demonstrate the effectiveness of implementation of the technical and technological solution under consideration.

scholarly journals PERFORMANCE OF PRESSURE TUBES IN CANDU REACTORS

2016 ◽  
Vol 5 (1) ◽  
pp. 1-15 ◽  
Author(s):  
Douglas Rodgers ◽  
Malcolm Griffiths ◽  
Grant Bickel ◽  
Andrew Buyers ◽  
Christopher Coleman ◽  
...  
Keyword(s):  
Tensile Strength ◽  
Ultimate Tensile Strength ◽  
Material Properties ◽  
Corrosion Behaviour ◽  
Alpha Phase ◽  
Operating Conditions ◽  
Grain Structure ◽  
Candu Reactors ◽  
Hexagonal Close Packed ◽  
Pressure Tubes

The pressure tubes in CANDU reactors typically operate for times up to about 30 years prior to refurbishment. The in-reactor performance of Zr-2.5Nb pressure tubes has been evaluated by sampling and periodic inspection. This paper describes the behavior and discusses the factors controlling the behaviour of these components. The Zr–2.5Nb pressure tubes are nominally extruded at 815 °C, cold worked nominally 27%, and stress relieved at 400 °C for 24 hours, resulting in a structure consisting of elongated grains of hexagonal close-packed alpha-Zr, partially surrounded by a thin network of filaments of body-centred-cubic beta-Zr. These beta-Zr filaments are meta-stable and contain about 20% Nb after extrusion. The stress-relief treatment results in partial decomposition of the beta-Zr filaments with the formation of hexagonal close-packed alpha-phase particles that are low in Nb, surrounded by a Nb-enriched beta-Zr matrix. The material properties of pressure tubes are determined by variations in alpha-phase texture, alpha-phase grain structure, network dislocation density, beta-phase decomposition, and impurity concentration that are a function of manufacturing variables. The pressure tubes operate at temperatures between 250 °C and 310 °C with coolant pressures up to about 11 MPa in fast neutron fluxes up to 4 × 1017 n·m−2·s−1 (E > 1 MeV) and the properties are modified by these conditions. The properties of the pressure tubes in an operating reactor are therefore a function of both manufacturing and operating condition variables. The ultimate tensile strength, fracture toughness, and delayed hydride-cracking properties (velocity (V) and threshold stress intensity factor (KIH)) change with irradiation, but all reach a nearly limiting value at a fluence of less than 1025 n·m−2 (E > 1 MeV). At this point the ultimate tensile strength is raised about 200 MPa, toughness is reduced by about 50%, V increases by about a factor of 6, while KIH is only slightly reduced. The role of microstructure and trace elements in these behaviours is described. Pressure tubes exhibit elongation, diametral expansion, and sag. The deformation behaviour is a function of operating conditions and the material properties that vary from tube-to-tube and as a function of axial location. Semi-empirical predictive models have been developed to describe the deformation response of average tubes as a function of operating conditions. The effect of material variability on corrosion behaviour is less well defined compared with other properties but there are instances where tube orientation and ingot source can be identified as factors that have an effect on hydrogen pick-up.

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