Sandia’s Supercritical CO2 Direct Cycle Gas Fast Reactor (SC-GFR) Concept

2011 ◽  
Author(s):  
Tom G. Lewis ◽  
Edward J. Parma ◽  
Steven A. Wright ◽  
Milton E. Vernon ◽  
Darryn D. Fleming ◽  
...  
Keyword(s):  
Fast Reactor ◽  
Thermal Efficiency ◽  
Power Conversion ◽  
Heat Removal ◽  
Working Fluid ◽  
Inlet Temperature ◽  
Brayton Cycle ◽  
Decay Heat ◽  
Long Life ◽  
Direct Cycle

The advanced nuclear concept group at Sandia National Laboratories has been investigating two advance right size reactors (RSR); this paper will discuss one of these two systems. The supercritical carbon dioxide (S-CO2), direct cycle gas fast reactor (SC-GFR) concept was developed to determine the feasibility of a RSR type concept using S-CO2 as the working fluid in a direct cycle fast reactor. Although a significant amount of work is still required, this type of reactor concept maintains some potentially significant advantages over ideal gas-cooled systems and liquid metal-cooled systems. The analyses presented in this paper show that a relatively small long-life reactor core could be developed that maintains decay heat removal by natural circulation. The SC-GFR concept is a relatively small (200 MWth) fast reactor that is cooled with CO2 at a pressure of 20 MPa. The CO2 flows out of the reactor vessel at ∼650°C directly into a turbine-generator unit to produce electrical power. The thermodynamic cycle that is used for the power conversion is a supercritical gas Brayton cycle with CO2 as the working fluid. With the CO2 gas near the critical point after the heat rejection portion of the cycle, it can be compressed with less power as compared to a standard gas Brayton cycle, thereby allowing for a higher thermal efficiency at the same turbine inlet temperature. A cycle efficiency of 45–50% is theoretically achievable for an optimized configuration. The major advantages of the concept include the following: • High thermal efficiency at relatively low reactor outlet temperatures; • Compact, cost-effective, power conversion system; • Non-flammable, stable, inert, non-toxic, inexpensive, and well-characterized coolant; • Potential long-life core and closed fuel cycle; • Small void reactivity worth from loss of coolant; • Natural convection decay heat removal; • Feasible design using today’s technologies. The goal of this work was to develop a SC-GFR concept and perform scoping analyses, including a review of other concepts that are similar in nature, to determine concept feasibility, advantages, disadvantages, and issues requiring further investigation. Overall, the SC-GFR concept as described in this paper appears feasible and warrants further study.

Cycle Calculations of a Small-Scale Heat Removal System With Supercritical CO2 As Working Fluid

2017 ◽  
Author(s):  
Marcel Strätz ◽  
Jörg Starflinger ◽  
Rainer Mertz ◽  
Michael Seewald ◽  
Sebastian Schuster ◽  
...  
Keyword(s):  
Power Plant ◽  
Supercritical Co2 ◽  
Heat Removal ◽  
Working Fluid ◽  
Small Scale ◽  
Brayton Cycle ◽  
Additional Heat ◽  
Decay Heat ◽  
Heat Removal System ◽  
Removal System

In case of an accident in a nuclear power plant with combined initiating events, (loss of ultimate heat sink and station blackout) additional heat removal system could transfer the decay heat from the core to and diverse ultimate heat sink. On additional heat removal system, which is based upon a Brayton cycle with supercritical CO2 as working fluid, is currently investigated within an EU-funded project, sCO2-HeRo (Supercritical carbon dioxide heat removal system). It shall serve as a self-launching, self-propelling and self-sustaining decay heat removal system to be used in severe accident scenarios. Since a Brayton cycle produces more electric power that it consumes, the excess electric power can be used inside the power plant, e.g. recharging batteries. A small-scale demonstrator will be attached to the PWR glass model at Gesellschaft für Simulatorforschung GfS, Essen, Germany. In order to design and build this small-scale model, cycle calculations are performed to determine the design parameters from which a layout can be derived.

Performance Characteristics of an Operating Supercritical CO2 Brayton Cycle

2012 ◽  
Author(s):  
Thomas Conboy ◽  
Steven Wright ◽  
James Pasch ◽  
Darryn Fleming ◽  
Gary Rochau ◽  
...  
Keyword(s):  
Supercritical Co2 ◽  
Waste Heat ◽  
Electrical Power ◽  
Heat Removal ◽  
Test Facility ◽  
Working Fluid ◽  
Inlet Temperature ◽  
Brayton Cycle ◽  
Compact Size ◽  
Test Loop

Supercritical CO2 (S-CO2) power cycles offer the potential for better overall plant economics due to their high power conversion efficiency over a moderate range of heat source temperatures, compact size, and potential use of standard materials in construction [1,2,3,4]. Sandia National Labs (Albuquerque, NM, US) and the US Department of Energy (DOE-NE) are in the process of constructing and operating a megawatt-scale supercritical CO2 split-flow recompression Brayton cycle with contractor Barber-Nichols Inc. [5] (Arvada, CO, US). This facility can be counted among the first and only S-CO2 power producing Brayton cycles anywhere in the world. The Sandia-DOE test-loop has recently concluded a phase of construction that has substantially upgraded the facility by installing additional heaters, a second recuperating printed circuit heat exchanger (PCHE), more waste heat removal capability, higher capacity load banks, higher temperature piping, and more capable scavenging pumps to reduce windage within the turbomachinery. With these additions, the loop has greatly increased its potential for electrical power generation — according to models, as much as 80 kWe per generator depending on loop configuration — and its ability to reach higher temperatures. To date, the loop has been primarily operated as a simple recuperated Brayton cycle, meaning a single turbine, single compressor, and undivided flow paths. In this configuration, the test facility has begun to realize its upgraded capacity by achieving new records in turbine inlet temperature (650°F/615K), shaft speed (52,000 rpm), pressure ratio (1.65), flow rate (2.7 kg/s), and electrical power generated (20kWe). Operation at higher speeds, flow rates, pressures and temperatures has allowed a more revealing look at the performance of essential power cycle components in a supercritical CO2 working fluid, including recuperation and waste heat rejection heat exchangers (PCHEs), turbines and compressors, bearings and seals, as well as auxiliary equipment. In this report, performance of these components to date will be detailed, including a discussion of expected operational limits as higher speeds and temperatures are approached.

A Supercritical CO2 Brayton Cycle Power Converter for a Sodium-Cooled Fast Reactor Small Modular Reactor

2015 ◽  
Author(s):  
James J. Sienicki ◽  
Anton Moisseytsev ◽  
Lubomir Krajtl
Keyword(s):  
Power Plant ◽  
Fast Reactor ◽  
Nuclear Power ◽  
Power Conversion ◽  
Electrical Power ◽  
Three Dimensional ◽  
Heat Removal ◽  
Power Converter ◽  
Brayton Cycle ◽  
Small Modular Reactor

Although a number of power conversion applications have been identified or have even been developed (e.g., waste heat recovery) for supercritical carbon dioxide (S-CO2) cycles including fossil fuel combustors, concentrated solar power (i.e., solar power towers), and marine propulsion, the benefits of S-CO2 Brayton cycle power conversion are especially prominent for applications to nuclear power reactors. In particular, the S-CO2 Brayton cycle is well matched to the Sodium-Cooled Fast Reactor (SFR) nuclear power reactor system and offers significant benefits for SFRs. The recompression closed Brayton cycle is highly recuperated and wants to operate with an approximate optimal S-CO2 temperature rise in the sodium-to-CO2 heat exchangers of about 150 °C which is well matched to the sodium temperature rise through the core that is also about 150 °C. Use of the S-CO2 Brayton cycle eliminates sodium-water reactions and can reduce the nuclear power plant cost per unit electrical power. A conceptual design of an optimized S-CO2 Brayton cycle power converter and supporting systems has been developed for the Advanced Fast Reactor – 100 (AFR-100) 100 MWe-class (250 MWt) SFR Small Modular Reactor (SMR). The AFR-100 is under ongoing development at Argonne National Laboratory (ANL) to target emerging markets where a clean, secure, and stable source of electricity is required but a large-scale power plant cannot be accommodated. The S-CO2 Brayton cycle components and cycle conditions were optimized to minimize the power plant cost per unit electrical power (i.e., $/kWe). For a core outlet temperature of 550 °C and turbine inlet temperature of 517 °C, a cycle efficiency of 42.3 % is calculated that exceeds that obtained with a traditional superheated steam cycle by one percentage point or more. A normal shutdown heat removal system incorporating a pressurized pumped S-CO2 loop slightly above the critical pressure on each of the two intermediate sodium loops has been developed to remove heat from the reactor when the power converter is shut down. Three-dimensional layouts of S-CO2 Brayton cycle power converter and shutdown heat removal components and piping have been determined and three-dimensional CAD drawings prepared. The S-CO2 Brayton cycle power converter is found to have a small footprint reducing the space requirements for components and systems inside of both the turbine generator building and reactor building. The results continue to validate earlier notions about the benefits of S-CO2 Brayton cycle power conversion for SFRs including higher efficiency, improved economics, elimination of sodium-water reactions, load following, and smaller footprint.

Cycle Calculations of a Small-Scale Heat Removal System With Supercritical CO2 as Working Fluid

2019 ◽  
Vol 5 (1) ◽  
Author(s):  
Marcel Straetz ◽  
Joerg Starflinger ◽  
Rainer Mertz ◽  
Dieter Brillert
Keyword(s):  
Carbon Dioxide ◽  
Power Plant ◽  
Heat Removal ◽  
Working Fluid ◽  
Small Scale ◽  
Brayton Cycle ◽  
Additional Heat ◽  
Decay Heat ◽  
Heat Removal System ◽  
Removal System

In the case of an accident in a nuclear power plant with combined initiating events (loss of ultimate heat sink and station blackout), an additional heat removal system could transfer the decay heat from the core to an ultimate heat sink (UHS). One specific additional heat removal system, based upon a Brayton cycle with supercritical carbon dioxide (CO2) as working fluid, is currently investigated within the European Union-funded project “sCO2-HeRo” (supercritical carbon dioxide heat removal system). It serves as a self-launching, self-propelling, and self-sustaining decay heat removal system used in severe accident scenarios. Since this Brayton cycle produces more electric power than it consumes, the excess electric power can be used inside the power plant, e.g., for recharging batteries. A small-scale demonstrator is attached to the pressurized water reactor (PWR) glass model at Gesellschaft für Simulatorschulung (GfS), Essen, Germany. In order to design and build this small-scale model, cycle calculations are performed to determine the design parameters from which a layout can be derived.

Scoping Studies for a Small Modular Lead-Cooled Fast Reactor

2004 ◽  
Author(s):  
Chenggang Yu ◽  
Michael A. Smith ◽  
Earl E. Feldman ◽  
Won Sik Yang ◽  
James J. Sienicki
Keyword(s):  
Carbon Dioxide ◽  
Fast Reactor ◽  
Natural Circulation ◽  
Power Conversion ◽  
Power Converter ◽  
Working Fluid ◽  
Brayton Cycle ◽  
Primary Coolant ◽  
The Core ◽  
Scoping Studies

A scoping design study has been carried out of the feasibility of a small, 25 MWt (∼10 MWe), modular lead-cooled fast reactor coupled to an advanced power converter consisting of a gas turbine Brayton cycle that utilizes supercritical carbon dioxide as the working fluid. Major constraints of the study are an ultralong 20 year core lifetime, near zero reactivity burnup swing over the core lifetime, Pb primary coolant natural circulation heat transport, road transportability of plant modular assemblies including the reactor and guard vessels, and high Brayton cycle power conversion efficiency. It is found that the goal of a near zero reactivity burnup swing implies a low core power density that results in an unacceptably low discharge burnup.

Preliminary Experimental Study of Precooler in Supercritical CO2 Brayton Cycle

2015 ◽  
Author(s):  
Seungjoon Baik ◽  
Seong Gu Kim ◽  
Seong Jun Bae ◽  
Yoonhan Ahn ◽  
Jekyoung Lee ◽  
...  
Keyword(s):  
Heat Exchanger ◽  
Thermal Efficiency ◽  
High Efficiency ◽  
Power Conversion ◽  
Inlet Temperature ◽  
Brayton Cycle ◽  
Test Results ◽  
Power Cycle ◽  
Compressor Inlet ◽  
House Design

The supercritical carbon dioxide (S-CO2) Brayton power conversion cycle has been receiving worldwide attention because of high thermal efficiency due to relatively low compression work near the critical point (30.98°C, 7.38MPa) of CO2. The S-CO2 Brayton cycle can achieve high efficiency with simple cycle configuration at moderate turbine inlet temperature (450∼650°C) and relatively high density of S-CO2 makes possible to design compact power conversion cycle. In order to achieve compact cycle layout, a highly compact heat exchanger such as printed circuit heat exchanger (PCHE) is widely used. Since, the cycle thermal efficiency is a strong function of the compressor inlet temperature in the S-CO2 power cycle, the research team at KAIST is focusing on the thermal hydraulic performance of the PCHE as a precooler. The investigation was performed by first developing a PCHE in-house design code named KAIST-HXD. This was followed by constructing the designed PCHE and testing it in the KAIST experimental facility, S-CO2PE. The test results of the PCHE were compared to the test results of a shell and tube type heat exchanger as well.

Performance Characteristics of an Operating Supercritical CO2 Brayton Cycle

2012 ◽  
Vol 134 (11) ◽  
Author(s):  
Thomas Conboy ◽  
Steven Wright ◽  
James Pasch ◽  
Darryn Fleming ◽  
Gary Rochau ◽  
...  
Keyword(s):  
Supercritical Co2 ◽  
Waste Heat ◽  
Electrical Power ◽  
Heat Removal ◽  
Test Facility ◽  
Working Fluid ◽  
Inlet Temperature ◽  
Brayton Cycle ◽  
Compact Size ◽  
Test Loop

Supercritical CO2 (S-CO2) power cycles offer the potential for better overall plant economics due to their high power conversion efficiency over a moderate range of heat source temperatures, compact size, and potential use of standard materials in construction. Sandia National Labs (Albuquerque, NM) and the U.S. Department of Energy (DOE-NE) are in the process of constructing and operating a megawatt-scale supercritical CO2 split-flow recompression Brayton cycle with contractor Barber-Nichols Inc. (Arvada, CO). This facility can be counted among the first and only S-CO2 power producing Brayton cycles anywhere in the world. The Sandia-DOE test-loop has recently concluded a phase of construction that has substantially upgraded the facility by installing additional heaters, a second recuperating printed circuit heat exchanger (PCHE), more waste heat removal capability, higher capacity load banks, higher temperature piping, and more capable scavenging pumps to reduce windage within the turbomachinery. With these additions, the loop has greatly increased its potential for electrical power generation, and its ability to reach higher temperatures. To date, the loop has been primarily operated as a simple recuperated Brayton cycle, meaning a single turbine, single compressor, and undivided flow paths. In this configuration, the test facility has begun to realize its upgraded capacity by achieving new records in turbine inlet temperature (650 °F/615 K), shaft speed (52,000 rpm), pressure ratio (1.65), flow rate (2.7 kg/s), and electrical power generated (20 kWe). Operation at higher speeds, flow rates, pressures, and temperatures has allowed a more revealing look at the performance of essential power cycle components in a supercritical CO2 working fluid, including recuperation and waste heat rejection heat exchangers (PCHEs), turbines and compressors, bearings and seals, as well as auxiliary equipment. In this report, performance of these components to date will be detailed, including a discussion of expected operational limits as higher speeds and temperatures are approached.

scholarly journals The Design of Turbomachinery for the Gas Turbine (Direct Cycle) High Temperature Gas Cooled Reactor Power Plant

1977 ◽  
Author(s):  
R. G. Adams ◽  
F. H. Boenig
Keyword(s):  
High Temperature ◽  
Power Plant ◽  
Gas Turbine ◽  
Power Conversion ◽  
Reactor Power ◽  
Working Fluid ◽  
Primary Coolant ◽  
Reactor Power Plant ◽  
Direct Cycle ◽  
High Temperature Gas

The Gas Turbine HTGR, or “Direct Cycle” High-Temperature Gas-Cooled, Reactor power plant, uses a closed-cycle gas turbine directly in the primary coolant circuit of a helium-cooled high-temperature nuclear reactor. Previous papers have described configuration studies leading to the selection of reactor and power conversion loop layout, and the considerations affecting the design of the components of the power conversion loop. This paper discusses briefly the effects of the helium working fluid and the reactor cooling loop environment on the design requirements of the direct-cycle turbomachinery and describes the mechanical arrangement of a typical turbomachine for this application. The aerodynamic design is outlined, and the mechanical design is described in some detail, with particular emphasis on the bearings and seals for the turbomachine.

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