scholarly journals Development and Analysis of Advanced High-Temperature Technology for Nuclear Heat Transport and Power Conversion

2010 ◽  
Author(s):  
Per F. Peterson
Author(s):  
Ali Afrazeh ◽  
Hiwa Khaledi ◽  
Mohammad Bagher Ghofrani

A gas turbine in combination with a nuclear heat source has been subject of study for some years. This paper describes the advantages of a gas turbine combined with an inherently safe and well-proven nuclear heat source. The design of the power conversion system is based on a regenerative, non-intercooled, closed, direct Brayton cycle with high temperature gas-cooled reactor (HTGR), as heat source and helium gas as the working fluid. The plant produces electricity and hot water for district heating (DH). Variation of specific heat, enthalpy and entropy of working fluid with pressure and temperature are included in this model. Advanced blade cooling technology is used in order to allow for a high turbine inlet temperature. The paper starts with an overview of the main characteristics of the nuclear heat source, Then presents a study to determine the specifications of a closed-cycle gas turbine for the HTGR installation. Attention is given to the way such a closed-cycle gas turbine can be modeled. Subsequently the sensitivity of the efficiency to several design choices is investigated. This model is developed in Fortran.


Author(s):  
Colin F. McDonald

Many variants of the nuclear closed Brayton cycle (NCBC) power plant have been studied over the last five decades, the ultimate goal being the introduction of a high efficiency and environmentally acceptable plant for electrical power generation. With an indirect cycle (IDC) plant the thermal energy from a high temperature reactor (HTR) is transferred to the helium gas turbine power conversion system via an intermediate heat exchanger. Compared with previous direct cycle variants the decoupling of the prime-mover from the reactor has the following advantages, 1) configuration flexibility (eased congestion), 2) good component access, 3) non radioactive power conversion system, 4) ease of maintenance, 5) use of conventional equipment, 6) reduced development effort, and 7) eased adaptability to a fossil-fired source. In addition to being a more practical configuration, a major attribute for the IDC is that it is compatible with long-term plans for development of a high temperature nuclear heat source (NHS) currently underway in Japan. With a NHS in place a logical progression of the HTR would be to deploy a power generation version using an IDC helium gas turbine. This paper sheds new light on the nuclear gas turbine in that it is no longer at the forefront of gas cooled reactor application studies, but rather could be a beneficiary of work currently underway in Japan to develop a nuclear heat source for high temperature process heat. The performance and major features of a future NCBC plant concept are highlighted in this paper. Depending on the market forces prevailing in Asia for small nuclear plants, the NCBC with an indirect cycle helium gas turbine could be available for service around the year 2020.


Author(s):  
Chang H. Oh ◽  
Eung Soo Kim ◽  
Steven Sherman

The Department of Energy and the Idaho National Laboratory are developing a Next Generation Nuclear Plant (NGNP) to serve as a demonstration of state-of-the-art nuclear technology. The purpose of the demonstration is two fold 1) efficient low cost energy generation and 2) hydrogen production. Although a next generation plant could be developed as a single-purpose facility dedicated to hydrogen production, early designs are expected to be dual purpose. While hydrogen production and advanced energy cycles are still in its early stages of development, research towards coupling a high temperature reactor with electrical generation and hydrogen production is under way. Many aspects of the NGNP must be researched and developed in order to make recommendations on the final design of the plant. Parameters such as working conditions, cycle components, working fluids, and power conversion unit configurations must be understood. A number of configurations of the power conversion unit were demonstrated in this study. An intermediate heat transport loop for transporting process heat to a High Temperature Steam Electrolysis (HTSE) hydrogen production plant was used. Helium, CO2, and a 80% nitrogen, 20% helium mixture (by weight) were studied to determine the best working fluid in terms cycle efficiency and development cost. In each of these configurations the relative component sizes were estimated for the different working fluids. Parametric studies were carried out on reactor outlet temperature, mass flow, pressure, and turbine cooling. Recommendations on the optimal working fluid for each configuration were made. Engineering analyses were performed for several configurations of the intermediate heat transport loop that transfers heat from the nuclear reactor to the hydrogen production plant. The analyses evaluated parallel and concentric piping arrangements and two different working fluids, including helium and a liquid salt. The thermal-hydraulic analyses determined the size and insulation requirements for the hot and cold leg pipes in the different configurations. Mechanical analyses were performed to determine hoop stresses and thermal expansion characteristics for the different configurations.


Author(s):  
R. G. Adams ◽  
F. H. Boenig

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.


2018 ◽  
Vol 136 ◽  
pp. 1557-1566 ◽  
Author(s):  
L. Barucca ◽  
S. Ciattaglia ◽  
M. Chantant ◽  
A. Del Nevo ◽  
W. Hering ◽  
...  

2013 ◽  
Vol 2013 (HITEN) ◽  
pp. 000056-000060 ◽  
Author(s):  
Z. Cole ◽  
B. S. Passmore ◽  
B. Whitaker ◽  
A. Barkley ◽  
T. McNutt ◽  
...  

In high frequency power conversion applications, the dominant mechanism attributed to power loss is the turn-on and -off transition times. To this end, a full-bridge silicon carbide (SiC) multi-chip power module (MCPM) was designed to minimize parasitics in order to reduce over-voltage/current spikes as well as resistance in the power path. The MCPM was designed and packaged using high temperature (> 200 °C) materials and processes. Using these advanced packaging materials and devices, the SiC MCPM was designed to exhibit low thermal resistance which was modeled using three-dimensional finite-element analysis and experimentally verified to be 0.18 °C/W. A good agreement between the model and experiment was achieved. MCPMs were assembled and the gate leakage, drain leakage, on-state characteristics, and on-resistance were measured over temperature. To verify low parasitic design, the SiC MCPM was inserted into a boost converter configuration and the switching characteristics were investigated. Extremely low rise and fall times of 16.1 and 7.5 ns were observed, respectively. The boost converter demonstrated an efficiency of > 98.6% at 4.8 kW operating at a switching frequency of 250 kHz. In addition, a peak efficiency of 96.5% was achieved for a switching frequency of 1.2 MHz and output power of 3 kW.


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