Steam and Power Conversion Systems

Information specific to steam and power conversion systems should also be provided on the following, where appropriate ... 

The power conversion system to produce electricity from the AHTR uses a multistage molten coolant gas cycle (MCGC)/ which is based on the GT-MHR power conversion unit (PCU). With similar power output, the MCGC system is expected to be more compact and, thus, provide the potential for major reductions in the turbine building volume and power conversion system capital cost for the AHTR relative to conventional systems that use a steam Rankine cycle. 

The high energy secondary piping systems of the System 80+ Standard Design conform to industry codes, standards, and regulatory design criteria as identified in CESSAR-DC Chapters 3 and 10, consistent with the acceptance criteria above. The systems are those which comprise the steam and power conversion segment of the plant, such as the Main Steam and the Condensate and Feedwater Systems, and are described in CESSAR-DC Chapter 10,... 

Analysis of the power eonversion system to produce electricity showed that the three-stage multireheat Brayton cyele with a turbine inlet temperature of 900°C ean yield a conversion effieiency of 54%. Two options were eonsidered—a pure hehum eyele and a nitrogen-helium cycle (10% hehum). The latter ease was found to result in a power conversion system that is physically 40% larger than the helium-only ease, although both eases are smaller than an equivalent steam eycle system because they avoid subatmospheric turbines and steam separators. 

In the NPPS based on the NPP technology, the reactor is successfully combined with a dynamic power conversion system operating in a closed gas turbine Brayton cycle (helium and xenon) or in a potassium steam turbine Ranldne cycle. 

The combination of the passively safe MHR and the gas turbine power conversion system represents the ultimate in simplicity and safety. The reactor coolant directly drives the turbine which turns the generator. This allows costly and failure prone steam generating equipment to be eliminated. Advantages include ... 

The primary coolant circuit was wholly contained within the PCRV with the core and reflectors located in the upper part of the cavity and the steam generators and circulators located in the lower part. The helium coolant flowed downward through the reactor core and was then directed into the reheater, superheater, evaporator, and economizer sections of the 12 steam generators. From the steam generators, the helium entered the four circulators and was pumped up around the outside of the core support floor and the core barrel before entering the plenum above the core. The superheated and reheated steam was converted to electricity in a conventional steam cycle power conversion turbine-generator system. 

Seismic design of the MARS will be performed in compliance with the procedures prescribed by the regulations. It could be noted, however, that the use of a gas-turbine unit facilitates the assurance of plant seismic resistance, as the specific mass of gas-turbine power conversion systems is -3-4.5 kg/kW and the specific volume is -0.04-0.17 mVkW, which is 10 times smaller than for the most updated steam turbine plants. 

The containment system design pressure is not affected by the primary system and can be limited by optimizing the water inventory in the secondary system in the designs that utilize steam cycle power conversion. 

The heat transport system is composed of a primary heat transport system (PHTS), an IHTS, and a power conversion system (PCS). The heat transport system has features such as pool-type PHTS, two IHTS loops, and a superheated steam Rankine cycle PCS, as shown in Fig. 13.5. 

In the ASTRID project, different power conversion systems (PCSs) are investigated based on the classical steam/water Rankine cycle and on an innovative gas (pure nitrogen) Brayton cycle. It is mainly motivated by enhanced safety and public acceptance with the practical elimination of the sodium/water reaction risk [22]. In this gas PCS, the main innovative component is the compact sodium gas heat exchanger (SGHE),... 

Alternatively, short-rotation hybrid poplar and selected grasses can be multicropped on an energy plantation in the U.S. Northwest and harvested for conversion to Hquid transportation fuels and cogenerated power for on-site use in a centrally located conversion plant. The salable products are Hquid biofuels and surplus steam and electric power. This type of design may be especially useful for larger land-based systems. 

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