scholarly journals Analyses of the Associated Technical and Economic Risks of the Simple and Intercooled Brayton Helium Recuperated Gas Turbine Cycles for Generation IV Nuclear Power Plants

2019 ◽  
Vol 5 (4) ◽  
Author(s):  
Arnold Gad-Briggs ◽  
Pericles Pilidis ◽  
Theoklis Nikolaidis

The simple cycle recuperated (SCR) and intercooled cycle recuperated (ICR) are highly efficient Brayton helium gas turbine cycles, designed for the gas-cooled fast reactor (GFR) and very-high-temperature reactor (VHTR) generation IV (Gen IV) nuclear power plants (NPPs). This paper documents risk analyses, which consider technical and economic aspects of the NPP. The sensitivity analyses are presented that interrogate the plant design, performance, and operational schedule and range from component efficiencies, system pressure losses, operating at varied power output due to short-term load-following or long-term reduced power operations to prioritize other sources such as renewables. The sensitivities of the economic and construction schedule are also considered in terms of the discount rates, capital and operational costs, and increased costs in decontamination and decommissioning (D&D) activity due to changes in the discount rates. This was made possible by using a tool designed for this study to demonstrate the effect on the “noncontingency” baseline levelized unit electricity cost (LUEC) of both cycles. The SCR with a cycle efficiency of 50% has a cheaper baseline LUEC of $58.41/MWh in comparison to the ICR (53% cycle efficiency), which has an LUEC of $58.70/MWh. However, the cost of the technical and economic risks is cheaper for the ICR resulting in a final LUEC of $70.45/MWh (ICR) in comparison to the SCR ($71.62/MWh) for the year 2020 prices.

Author(s):  
Arnold Gad-Briggs ◽  
Pericles Pilidis ◽  
Theoklis Nikolaidis

A framework – NuTERA (Nuclear Techno-Economic and Risk Assessment) has been developed to set out the requirements for evaluating Generation IV (Gen IV) Nuclear Power Plants (NPPs) at the design conceptual stage. The purpose of the framework is to provide guidelines for future tools that are required to support the decision-making process on the choice of Gen IV concepts and cycle configurations. In this paper, the underpinning of the framework has been demonstrated to enable the creation of an analyses tool, which evaluates the design of an NPP that utilises helium closed Brayton gas turbine cycles. The tool at the broad spectrum focuses on the component and cycle design, Design Point (DP) and Off-Design Point (ODP) performance, part power and load following operations. Specifically, the design model has been created to provide functionalities that look at the in-depth sensitivities of the design factors and operation that affect the efficiency of an NPP such as temperature and pressure ratios, inlet cycle temperatures, component efficiencies, pressure losses. The ODP performance capabilities include newly derived component maps for the reactor, intercooler and recuperator for long term Off-Design (OD) operation. With regard to short term OD, which is typically driven by changes in ambient conditions, the ability to analyse the cycle load following capabilities are possible. An economic model has also been created, which calculates the component costs and the baseline economic evaluation. An incorporated risk model quantifies the performance, operational, financial and design impact risks. However, the tool is able to optimise the NPP cycle configuration based on the best economics using the Levelised Unit Electricity Cost (LUEC) as a measure. The tool has been used to demonstrate a typical decision-making process on 2 Gen IV helium closed gas turbine cycles, which apply to the Gas-cooled Fast Reactors (GFRs) and Very-High Temperature Reactors (VHTRs). The cycles are the Simple Cycle Recuperator (SCR) and Intercooled Cycle Recuperator (ICR). The tool was able to derive the most efficient cycle configurations for the ICR (53% cycle efficiency) and SCR (50% cycle efficiency). Based on these efficiency figures, the baseline LUEC ($/MWh) for the year 2020 is $62.13 for the ICR and $61.84 for the SCR. However, the inclusion of the cost of contingencies due to risks and the subsequent economic optimisation resulted in a cost of $69.70 and $69.80 for the ICR and SCR respectively.


Author(s):  
A. Gad-Briggs ◽  
P. Pilidis ◽  
T. Nikolaidis

Previous analyses of generation IV (GEN IV) helium gas turbine cycles indicated the possibility for high turbine entry temperatures (TETs) up to 1200 °C in order to improve cycle efficiency, using improved turbine blade material and optimum turbine cooling fractions. The purpose of this paper is to understand the effect on the levelized unit electricity cost (LUEC) of the nuclear power plant (NPP), when the TET is increased to 1200 °C from an original TET of 950 °C and when an improved turbine blade material is used to reduce the turbine cooling fraction. The analyses focus on the simple cycle recuperated (SCR) and the intercooled cycle recuperated (ICR). The baseline LUECs of the NPPs were calculated as $61.84/MWh (SCR) and $62.16/MWh for a TET of 950 °C. The effect of changing the turbine blades improved the allowable blade metal temperature by 15% with a reduction in the LUEC by 0.6% (SCR) and 0.7% (ICR). Furthermore, increasing the TET to 1200 °C has a significant effect on the power output but more importantly it reduces the LUECs by 22.7% (SCR) and 19.8% (ICR). The analyses intend to aid development of the SCR and ICR including improving the decision making process on choice of cycles applicable to the gas-cooled fast reactors (GFRs) and very high-temperature reactors (VHTRs), where helium is the coolant.


2020 ◽  
Vol 7 (1) ◽  
Author(s):  
Arnold Gad-Briggs ◽  
Emmanuel Osigwe ◽  
Pericles Pilidis ◽  
Theoklis Nikolaidis ◽  
Suresh Sampath ◽  
...  

Abstract Numerous studies are on-going on to understand the performance of generation IV (Gen IV) nuclear power plants (NPPs). The objective is to determine optimum operating conditions for efficiency and economic reasons in line with the goals of Gen IV. For Gen IV concepts such as the gas-cooled fast reactors (GFRs) and very-high temperature reactors (VHTRs), the choice of cycle configuration is influenced by component choices, the component configuration and the choice of coolant. The purpose of this paper to present and review current cycles being considered—the simple cycle recuperated (SCR) and the intercooled cycle recuperated (ICR). For both cycles, helium is considered as the coolant in a closed Brayton gas turbine configuration. Comparisons are made for design point (DP) and off-design point (ODP) analyses to emphasize the pros and cons of each cycle. This paper also discusses potential future trends, include higher reactor core outlet temperatures (COT) in excess of 1000 °C and the simplified cycle configurations.


2019 ◽  
Vol 5 (2) ◽  
Author(s):  
Nicolás Alejandro Malinovsky

This work shows the introduction of the Electrical Power System Analysis (etap) software as a calculation and analysis tool for power electrical systems of the nuclear power plants (NPP) under the orbit of Nucleoeléctrica Argentina S.A (NASA). Through the use of the software, the model of the electrical power system of the Atucha II NPP was developed. To test the functionality of the modeled electrical power circuit, studies of load flow and short-circuit analysis were conducted, yielding satisfactory results, which were contrasted with the plant design values. Once the model has been validated, this will be the basis for carrying out different studies in the plant through simulation. Furthermore, with the incorporation of etap as a fundamental calculation and analysis tool for power electrical systems at the company's engineering departments, it is expected to improve the safety, operation, quality, reliability, and maintenance of both the Atucha II NPP electrical power system and the other nuclear power plants operated by Nucleoeléctrica Argentina S.A.


Author(s):  
S. Herstead ◽  
M. de Vos ◽  
S. Cook

The success of any new build project is reliant upon all stakeholders — applicants, vendors, contractors and regulatory agencies — being ready to do their part. Over the past several years, the Canadian Nuclear Safety Commission (CNSC) has been working to ensure that it has the appropriate regulatory framework and internal processes in place for the timely and efficient licensing of all types of reactor, regardless of size. This effort has resulted in several new regulatory documents and internal processes including pre-project vendor design reviews. The CNSC’s general nuclear safety objective requires that nuclear facilities be designed and operated in a manner that will protect the health, safety and security of persons and the environment from unreasonable risk, and to implement Canada’s international commitments on the peaceful use of nuclear energy. To achieve this objective, the regulatory approach strikes a balance between pure performance-based regulation and prescriptive-based regulation. By utilizing this approach, CNSC seeks to ensure a regulatory environment exists that encourages innovation within the nuclear industry without compromising the high standards necessary for safety. The CNSC is applying a technology neutral approach as part of its continuing work to update its regulatory framework and achieve clarity of its requirements. A reactor power threshold of approximately 200 MW(th) has been chosen to distinguish between large and small reactors. It is recognized that some Small Modular Reactors (SMRs) will be larger than 200 MW(th), so a graded approach to achieving safety is still possible even though Nuclear Power Plant design and safety requirements will apply. Design requirements for large reactors are established through two main regulatory documents. These are RD-337 Design for New Nuclear Power Plants, and RD-310 Safety Analysis for Nuclear Power Plants. For reactors below 200 MW(th), the CNSC allows additional flexibility in the use of a graded approach to achieving safety in two new regulatory documents: RD-367 Design of Small Reactors and RD-308 Deterministic Safety Analysis for Small Reactors. The CNSC offers a pre-licensing vendor design review as an optional service for reactor facility designs. This review process is intended to provide early identification and resolution of potential regulatory or technical issues in the design process, particularly those that could result in significant changes to the design or analysis. The process aims to increase regulatory certainty and ultimately contribute to public safety. This paper outlines the CNSC’s expectations for applicant and vendor readiness and discusses the process for pre-licensing reviews which allows vendors and applicants to understand their readiness for licensing.


1970 ◽  
Author(s):  
W. Endres

A short review of the state-of-the-art of the closed cycle gas turbine technology is given and the future requirements for large helium turbines are described. The necessary development of components and turbine sizes is outlined. In a second part of the paper the configuration and layout of power plants with gas turbines are discussed.


2018 ◽  
Vol 2 (1) ◽  

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].


2020 ◽  
Vol 6 (2) ◽  
Author(s):  
Emmanuel O. Osigwe ◽  
Arnold Gad-Briggs ◽  
Theoklis Nikolaidis ◽  
Pericles Pilidis ◽  
Suresh Sampath

Abstract A significant hurdle in the development of performance simulation tools to analyze and evaluate nuclear power plants (NPP) is finding data relating to component performance maps. As a result, engineers often rely on an estimation approach using various scaling techniques. The purpose of this study is to determine the component characteristics of a closed-cycle gas turbine NPP using the existing component maps with the corresponding design data. The design data are applied for different working fluids using a multifluid scaling approach to adapt data from one component map into another. The multifluid scaling technique described herein was developed as an in-house computer simulation tool. This approach makes it easy to theoretically scale the existing maps using similar or different working fluids without carrying out a full experimental test or repeating the whole design and development process. The results of selected case studies show a reasonable agreement with the available data. The analyses intend to aid the development of cycles for Generation IV NPPs specifically gas-cooled fast reactors (GFRs) and very high-temperature reactors (VHTRs).


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