3.9 NUCLEAR CLOSED BRAYTON CYCLE (CONCEPT 8) The energy source in this system is nuclear; a molten salt breeder reactor (MSBR) is used. The salt mixture contains both, fissile fuel, the energy source, and fertile fuel which breeds to become fuel for subsequent use. The salt mixture is circulated out of the reactor core through a heat exchanger which transfers energy to the helium loop of the Brayton turbomachines. A small secondary salt flow is continuously passed through a fuel process system. This system removes the protactinium and wastes which would "poison" the reactor by excessive neutron capture. The fuel process system introduces fertile fuel and removes bred fuel. The MSBR is an unique breeder concept in that a single fuel mixture contains both fissile and fertile fuels, and that processing of solid fuel elements is not required. The Brayton cycle turbomachine provides a rotating shaft output which drives the generators. Hot helium is expanded through the gas turbine, providing power to drive both the compressors and generators. The recuperator exchanges energy across the loop to increase efficiency. Waste heat is rejected through a gas-to-liquid heat exchanger to a liquid metal cooling loop; the liquid metal pumps use power drawn from the generators. The 50,000 volt AC output of the generators is stepped-up to 382,000 volts in transformers; this high voltage facilitates on-board distribution. Stepdown occurs in the rotary transformers. An AC to DC converter is used to provide the DC required to energize the transmitter. The nuclear Brayton cycle system is shown in Figure 3-8. Fig. 3-8. Nuclear Thermionic System 3.10 POWER TRANSFER SYSTEM (CONCEPT 9) In this concept one or more mirrors in geosynchronous orbit would reflect solar energy directly to Earth. Ground-based solar power plants would be augmented by this reflected energy, allowing night operation or increased output. 3.11 EMPHASIZED CONCEPTS By the end of the initial phase of this study, it had become evident that further investigation of concepts 2, 4, 7 and 9 was inappropriate for the reasons given in Table 3-2. Table 3-2. Evaluation of De-emphasized Systems
RkJQdWJsaXNoZXIy MTU5NjU0Mg==