Power conversion systems

Remove core decay heat High pressure injection system Low pressure injection system High pressure recirculation system Core flood tanks Auxiliary feedwater system Power conversion system Remove core decay heat Auxiliary feedwal stem Power conversion m High pressure inj( i system pow. peiuicd relief valves... 

To conclude we may speculate on the future of the fuel cell research and make some observations. After much hope of achieving a cheap, reliable and efficient power conversion system, the hard facts of life have shown that the rapid commercialization and wide spread use of fuel cells cannot be obtained so readily. The level of R and D funding after the bonanza years of the moon flight missions rapidly decreased in the late sixties and several programs in industry came to a halt. The recent and exhaustive review by Kordesch ( 1). on fuel cell development indicates, among other things, that the peak in R and D in this field was in 1964. The maximum number of publications in fuel cell research activity occurred in 1969. 

Fundamental to all heat-power conversion systems is that a significant portion of the heat supplied to the system must be rejected. Depending on their heat-power conversion efficiency, fossil-fueled plants waste 40-60%, nuclear-fueled plants 60-70% of the heat input geothermal power plants make no exception here. 

The coupled nuclear-hydrogen plant investigated in this paper was studied in earlier work (Vilim, 2007). There the full power condition and the combined plant efficiency were estimated. The plant appears in Figures 1 through 3 as three modules - the primary system, the power conversion system and the high-temperature electrolysis plant. The interface between the nuclear side and the chemical plant appears in these figures in the form of the flow paths that connect these three modules. 

In South Africa, the large national utility, Eskom, which has an installed generation capacity of about 38,000 MWe, is in the process of performing a technical and economic evaluation of a helium-cooled pebble bed module reactor. It would be directly coupled to a gas turbine power conversion system for consideration in increasing the capacity of the utility s electrical system. 

Methane partial oxidation fuel cells with nuclear heat, called Multi Power Conversion System by HTGR (S. Ishiyama - JAERI, Figure 3, Ref. 8). 

Figure 3. Concept of multi power conversion system by HTGR...

Yan, X., et al, (2003b), Cost and performance design approach for GTHTR300 power conversion system. Nucl. Eng. Des. 226, 351-373. 

S. Atcitty, S. Ranade, A. Gray-Fenne, Summary of State-of-the-Art Power Conversion Systems for Energy Storage Applications, SAND98-20I9, September 1998, Sandia National Laboratories, Albuquerque, NM, USA. 

A gas-cooled nuclear reactor was chosen due to its simplicity and suitability for the space environment. There are numerous alternatives for cooling a reactor core, but gas cooling is one of the simpler methods and most attractive when used with a closed Brayton cycle (CBC) power conversion system. The use of other reactor coolants would necessitate the inclusion of a heat exchanger and introduce complicated freeze/thaw problems, increasing the complexity and the weight of the reactor. 

A Closed Brayton Cycle will be used for the power conversion system. This cycle has the advantage of being a well understood and robust power conversion cycle. Extensive testing of similar systems gives confidence in the long-term durability of this system... 

Brayton conversion systems have advantages and disadvantages. They are more efficient than most static power conversion systems (e g., thermoelectric or thermionic based systems), and they are more durable and simpler than the other dynamic power conversion systems. However, Brayton cycles do require higher temperatures to achieve the same efficiency as other dynamic power conversion systems. The energy density of the working fluid is low compared to the other dynamic power conversion systems. 

Testing of the power conversion components as an integral system utilizing a nonnuclear heat source is seen as a prerequisite prior to connection to the reactor. The thermodynamic performance of the power conversion system can be demonstrated and verified to full temperature and speed conditions at considerably lower pressures then the plant design pressure. A proposal from Japan utilizes an electrical heater as the primary energy supply. Due to the high efficiency of the power conversion system, an outside power supply of only approximately 10% of the thermal plant rating would be required for a test of this nature. 

STATUS OF GT-MHR WTIH EMPHASIS ON THE POWER CONVERSION SYSTEM... 

Etzel, K., G. Baccaglini, A. Schwartz, S. Hillman, and D. Mathis, GT-MHR Power Conversion System Design Status and Technical Issues, GA-A21827, December 1994, Presented at the IAEA Technical Committee Meeting on Development Status of Modular High Temperature Reactors and Their Future Role, November 28-30, 1994, ECN, Petten, The Netherlands. 

C.F. McDonald, F.A. Silady, R.M. Wright, K.F. Kretzinger and R.C. Haubert,"GT-MHR Helium Gas Turbine Power Conversion System Design and Development", GA-A21617, GA Project 9819, March 1994. 

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