scholarly journals Dependence of the Possible and Allowable Projection Error on the Projection Time Frame

2021 ◽  
pp. 5-8
Author(s):  
Y. Kononov ◽  
D. Kononov
Keyword(s):  
Nuclear Power ◽  
Power Plants ◽  
Time Frame ◽  
Projection Methods ◽  
Combined Cycle ◽  
Data Uncertainty ◽  
Uncertainty Range ◽  
Regional Energy ◽  
Projection Error ◽  
Gas Price

This study addresses the issues of assessing and factoring in the effect of uncertainty growth on the possible performance of projections and their allowable errors. Relying on projects of nuclear power plants and combined cycle power plants as a case study, we assess the dependence of their economic performance indicators on possible changes in the conditions of their future operation in a given year. To assess the effect of the range and nature of input data uncertainty on the projections of the development of regional energy supply systems, we proposed a methodological toolkit that combines optimization with the Monte Carlo simulation. Its application to one of the options for commissioning new power plants in European Russia enabled us to estimate the possible response of the average and marginal cost of electricity in this aggregated region to the broadening of the uncertainty range of the gas price. We note that the assessment and comparison of the possible error of projected indicators with the requirements for their accuracy in making priority investment and other decisions facilitate the justification of the acceptable complexity of employed models and projection methods.

scholarly journals Cyclic Energy Demands Supplied Economically With Gas Turbines and Combined Cycle Plants

1971 ◽  
Author(s):  
H. L. Smith ◽  
R. J. Budenholzer
Keyword(s):  
Gas Turbines ◽  
Nuclear Power ◽  
Power Plants ◽  
Electric Utility ◽  
Combined Cycle ◽  
Electric Utility Industry ◽  
Utility Industry ◽  
New Class ◽  
Energy Demands ◽  
Distillate Fuel

The electric utility industry is finding a need for a new class of generation termed intermediate. This paper presents results of generation addition pattern studies performed to determine the relative merits of steam peaking plants and combined cycle plants in filling these needs. Corresponding optimum addition patterns are established for simple cycle gas turbine and nuclear power plants. The combined cycle and steam peaking plants are shown to be comparable at high cost levels, while the combined cycle shows definite advantage if permitted to burn non-distillate fuel.

scholarly journals Feasibility of replacement of nuclear power with other energy sources in the Czech republic

2020 ◽  
Vol 24 (6 Part A) ◽  
pp. 3543-3553
Author(s):  
Pavel Charvat ◽  
Lubomir Klimes ◽  
Jiri Pospisil ◽  
Jiri Klemes ◽  
Petar Varbanov
Keyword(s):  
Czech Republic ◽  
Natural Gas ◽  
Nuclear Power ◽  
Power Plants ◽  
Fossil Fuels ◽  
Renewable Energy Sources ◽  
Combined Cycle ◽  
Energy Sources ◽  
The Czech Republic ◽  
The Moment

The feasibility and consequences of replacing nuclear power plants (NPP) in the Czech Republic with other energy sources are discussed. The NPP produced about one-third of electricity in the Czech Republic in 2017. Renewable energy sources such as hydropower, wind and solar power plants and biomass/biogas burning power plants produced about 11% of electricity in 2017. Due to the geographical and other constraints (intermittency, land footprint, and public acceptance), the renewables do not have the potential to entirely replace the capacity of the NPP. The only feasible technologies that could replace NPP in the Czech Republic in the near future are the power plants using fossil fuels. The combined cycle power plants running on natural gas (NGCC) are technically and environmentally fea-sible alternative for NPP at the moment. However, the natural gas imports would increase by two-thirds and the total greenhouse gas emissions would go up by about 10% if the power production of the NPP was entirely replaced by NGCC in the Czech Republic.

Diagnosis of Thermal Efficiency of Nuclear Power Plants Using Optical Torque Sensors

2006 ◽  
Author(s):  
Shuichi Umezawa ◽  
Jun Adachi
Keyword(s):  
Power Plant ◽  
Nuclear Power Plant ◽  
Thermal Efficiency ◽  
Nuclear Power ◽  
Power Plants ◽  
Nuclear Power Plants ◽  
Torsional Rigidity ◽  
Combined Cycle ◽  
Sensor Performance ◽  
Optical Torque

A new optical torque measuring method was applied to diagnosis of thermal efficiency of nuclear power plants. The sensor allows torque deformation of the rotor caused by power transmission to be measured without contact. Semiconductor laser beams and small pieces of stainless reflector that have bar-code patterns are employed. The intensity of the reflected laser beam is measured and then input into a computer through an APD and an A/D converter having high frequency sampling rates. The correlation analysis technique can translate these data into the torque deformation angle. This angle allows us to obtain the turbine output along with the torsional rigidity and the rotating speed of the rotor. The sensor was applied to a nuclear plant of Tokyo Electric Power Company, TEPCO, following its application success to the early combined cycle plants and the advanced combined cycle plants of TEPCO. As the turbine rotor of the nuclear power plant is less exposed than that of the combined cycle plants, the measurement position is confined to a narrow gap. In order to overcome the difficulty in installation, the shape of the sensor is modified to be long and thin. Sensor performance of the nuclear power plant was inspected over a year. The value of the torsional rigidity was analyzed by the finite element method at first. Accuracy was improved by correcting the torsional rigidity so that the value was consistent with the generator output. As a result, it is considered that the sensor performance has reached a practical use level.

Research on Thermal Efficiencies of Various Power Cycles for GFRs and VHTRs

2018 ◽  
Author(s):  
Mohammed Mahdi ◽  
Roman Popov ◽  
Igor Pioro
Keyword(s):  
Gas Turbine ◽  
Heavy Water ◽  
Nuclear Power ◽  
Power Plants ◽  
Supercritical Pressure ◽  
Combined Cycle ◽  
Power Cycles ◽  
Power Cycle ◽  
Combined Cycles ◽  
Gas Turbine Cycle

The vast majority of Nuclear Power Plants (NPPs) are equipped with water- and heavy-water-cooled reactors. Such NPPs have lower thermal efficiencies (30–36%) compared to those achieved at NPPs equipped with Advanced Gas-cooled Reactors (AGRs) (∼42%) and Sodium-cooled Fast Reactors (SFRs) (∼40%), and, especially, compared to those of modern advanced thermal power plants, such as combined cycle with thermal efficiencies up to 62% and supercritical-pressure coal-fired power plants — up to 55%. Therefore, NPPs with water- and heavy-water-cooled reactors are not very competitive with other power plants. Therefore, this deficiency of current water-cooled NPPs should be addressed in the next generation or Generation-IV nuclear-power reactors / NPPs. Very High Temperature Reactor (VHTR) concept / NPP is currently considered as the most efficient NPP of the next generation. Being a thermal-spectrum reactor, VHTR will use helium as a reactor coolant, which will be heated up to 1000°C. The use of a direct Brayton helium-turbine cycle was considered originally. However, technical challenges associated with the direct helium cycle have resulted in a change of the reference concept to indirect power cycle, which can be also a combined cycle. Along with the VHTR, Gas-cooled Fast Reactor (GFR) concept / NPP is also regarded as one of the most thermally efficient concept for the upcoming generation of NPPs. This concept was also originally thought to be with the direct helium power cycle. However, technical challenges have changed the initial idea of power cycle to a number of options including indirect Brayton cycle with He-N2 mixture, application of SuperCritical (SC)-CO2 cycles or combined cycles. The objective of the current paper is to provide the latest information on new developments in power cycles proposed for these two helium-cooled Generation-IV reactor concepts, which include indirect nitrogen-helium Brayton gas-turbine cycle, supercritical-pressure carbon-dioxide Brayton gas-turbine cycle, and combined cycles. Also, a comparison of basic thermophysical properties of helium with those of other reactor coolants, and with those of nitrogen, nitrogen-helium mixture and SC-CO2 is provided.

Reheat Air-Brayton Combined Cycle Power Conversion Off-Nominal and Transient Performance

2014 ◽  
Vol 136 (7) ◽  
Author(s):  
Charalampos Andreades ◽  
Lindsay Dempsey ◽  
Per F. Peterson
Keyword(s):  
Natural Gas ◽  
Gas Turbine ◽  
Nuclear Power ◽  
Power Plants ◽  
Power Conversion ◽  
Companion Paper ◽  
Combined Cycle ◽  
Natural Gas Combined Cycle ◽  
Reference Design ◽  
Molten Fluoride

Because molten fluoride salts can deliver heat at temperatures above 600 °C, they can be used to couple nuclear and concentrating solar power heat sources to reheat air combined cycles (RACC). With the open-air configuration used in RACC power conversion, the ability to also inject natural gas or other fuel to boost power at times of high demand provides the electric grid with contingency and flexible capacity while also increasing revenues for the operator. This combination provides several distinct benefits over conventional stand-alone nuclear power plants and natural gas combined cycle and peaking plants. A companion paper discusses the necessary modifications and issues for coupling an external heat source to a conventional gas turbine and provides two baseline designs (derived from the GE 7FB and Alstom GT24). This paper discusses off-nominal operation, transient response, and start-up and shutdown using the GE 7FB gas turbine as the reference design.

Comparative Evaluation of Power Plants With Regard to Technical, Ecological and Economical Aspects

2001 ◽  
Author(s):  
Alex Lezuo ◽  
Robert Taud
Keyword(s):  
Life Cycle Cost ◽  
Power Plants ◽  
Coal Gasification ◽  
Time Frame ◽  
Combined Cycle ◽  
Fluidized Bed Combustion ◽  
Ecological Data ◽  
Economical Analysis ◽  
Generation Costs ◽  
Steam Parameters

The development of efficiency of gas turbine based combined cycle plants has been very fast during the last 10 years and has reached now a value of close to 60 %. This value is well above that of coal power plants or other technologies. Even though development has been going on in these fields as well. For a fairly comprehensive reorientation and status evaluation with the time frame of 2005 in focus, a comparative study with equal boundary conditions has been performed considering coal steam plants with various steam parameters, fluidized bed combustion, coal gasification and natural gas fired combined cycle plants. Besides investment also technical differences and ecological data are given. The final evaluation of power generation technologies is based however mainly on its electricity generation costs or life cycle cost. Considering today’s fuel prices and price development projections over the plant life times, an economical analysis has been performed and will be presented, serving also as framework for project and investment decisions.

scholarly journals Why We Need Nuclear Power Plants

2018 ◽  
Vol 2 (1) ◽  
Keyword(s):  
Power Plant ◽  
Natural Gas ◽  
Gas Turbine ◽  
Nuclear Power ◽  
Power Plants ◽  
Nuclear Power Plants ◽  
Rankine Cycle ◽  
Combined Cycle ◽  
Brayton Cycle ◽  
Gen Iv

The major growth in the electricity production industry in the last 30 years has centered on the expansion of natural gas power plants based on gas turbine cycles. The most popular extension of the simple Brayton gas turbine has been the combined cycle power plant with the Air-Brayton cycle serving as the topping cycle and the Steam-Rankine cycle serving as the bottoming cycle for new generation of nuclear power plants that are known as GEN-IV. The Air-Brayton cycle is an open-air cycle and the Steam-Rankine cycle is a closed cycle. The air-Brayton cycle for a natural gas driven power plant must be an open cycle, where the air is drawn in from the environment and exhausted with the products of combustion to the environment. This technique is suggested as an innovative approach to GEN-IV nuclear power plants in form and type of Small Modular Reactors (SMRs). The hot exhaust from the AirBrayton cycle passes through a Heat Recovery Steam Generator (HSRG) prior to exhausting to the environment in a combined cycle. The HRSG serves the same purpose as a boiler for the conventional Steam-Rankine cycle [1].

Application of Uncertainty Analysis in the Comparison of Void Fraction Calculations With Experiment

2010 ◽  
Author(s):  
Jason Pascoe ◽  
Yuksel Parlatan ◽  
B. McLaughlin ◽  
Sophia Fung
Keyword(s):  
Void Fraction ◽  
Nuclear Power ◽  
Power Plants ◽  
Computer Code ◽  
Scientific Basis ◽  
Output Parameter ◽  
Test Facility ◽  
Model Parameters ◽  
Uncertainty Range ◽  
Test Loop

Safety analysis computer codes are designed to simulate phenomena relevant to the assessment of normal and transient behaviour in nuclear power plants. In order to do so, models of relevant phenomena are developed and a set of such models constitutes a computer code. In accident or transient analysis the values of certain output parameters (margin parameters) are used to characterize the severity of the event. The accuracy of the computer code in calculating these margin parameters is usually obtained through validation and variation in the margin parameter is estimated through the propagation of variation in the code input. A method for estimating code uncertainty respect to a specific output parameter has been developed. The methodology has the following basic elements: (1) specification and ranking of phenomena that govern the behaviour of the output parameter for which an uncertainty range is required; (2) identification of models within the code that represent the relevant phenomena; (3) determination of the governing parameters for the phenomenological models and Identification of uncertainty ranges for the governing model parameters from validation or scientific basis, if available; (4) decomposition of the governing model parameters into related parameters; (5) identification of uncertainty ranges for the modelling parameters for use in Best Estimate Analysis; (6) design and execution of a case matrix; and (7) estimation of the code uncertainty through quantification of the variability in output parameters arising from uncertainty in modelling parameters. This methodology has been employed using simulations of Large Break Loss of Coolant Accident (LOCA) tests in the RD-14M test facility to calculate the uncertainty in the TUF thermal hydraulics code calculation of the coolant void fraction. The uncertainty has been estimated with and without plant parameters (parameters specific to the RD-14M test loop). The TUF coolant void fraction uncertainty without plant parameters was determined to be 0.08 while the uncertainty with plant parameters included was determined to be 0.11. The uncertainty value without plant parameters included is comparable to the uncertainty in the measurements (0.09). The uncertainty value with plant parameters included is larger than the variation in the bias (0.10) of the TUF calculation of void fraction. From these findings, it can be concluded that the estimated accuracy of the TUF code calculation of void fraction is consistent with the available experimental data.

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