The plant area will be about 70 acres, including the reactor building, switchyard, parking lot, access roads, and wet cooling towers. As a minimum, a buffering area of 400 acres is needed. Thus with other physical facilities, a total area of 1000 to 1200 acres is needed. The 1000-MWe LMFBR design (about 2500 MWt) was scaled up to 1250 MWe because the cost estimate is also based on this plant and major equipment. The LMFBR primary system consists of a liquid sodium-cooled nuclear reactor having a reactor core containing low-enriched (about 11-15%) uranium and plutonium oxides in approximately 400 fuel-and-blanket assemblies. The core is refueled by replacing approximately one-third of the assemblies after achieving a 53,000 MW-d/t average burnup. Both the new and spent reactor fuels are intensely radioactive and must be stored in heavily shielded areas. The reactor produces approximately 3417 MWt at nominal full power. The LMFBR heat transport system removes the heat generated by the reactor core and converts it to the rotational mechanical energy required by the generator to produce electric power. The overall system consists of a radioactive primary coolant (liquid sodium) system, a nonradioactive secondary coolant (also liquid sodium) system, a steam generation system, and a steam plant system, the latter including the turbine that delivers the required mechanical energy to the electrical generator. A simplified system diagram is given in Fig. 3.10. The primary coolant system consists of several redundant circulating loops that conduct sodium from the core exit plenum of the reactor vessel and circulate it through intermediate heat exchangers. Here, the heat is transferred to the sodium of the secondary coolant system. The primary sodium then returns to the reactor vessel. In the secondary system, secondary sodium is heated in the intermediate heat exchangers and is circulated to the steam generation system. There are four parallel primary loops and four secondary loops, one serving each primary loop. Two basic arrangements for the primary coolant system have been proposed: the pool-type and the loop-type configurations. These are depicted schematically in Fig. 3.11. In the pool-type configuration, the reactor, intermediate heat exchangers, primary pumps, and interconnecting piping are all immersed in a large primary tank filled with sodium. During operation, sodium is drawn from the bulk content of the tank by the primary pumps and is forced through the reactor. Then, the sodium flows by gravity through the intermediate heat exchangers and discharges back to the bulk sodium in the primary tank. The driving force for the intermediate heat exchanger flow is the difference between the level of sodium over the reactor and that in the remainder of the primary tanks. With this configuration, the primary tank with its cover and the tubes and tube sheets of the intermediate heat exchangers constitute the primary coolant system boundary. In the loop-type configuration, the primary pumps and the intermediate heat exchangers are located outside the reactor vessel. Either hot-leg or cold-leg pumps could be used in the primary system. The primary loop piping is elevated, and guard vessels are provided around the pump, intermediate heat exchanger, and reactor vessel so that leaks in the primary piping or these components cannot cause the sodium level in the reactor to drop below the minimum safe level. The loop nozzles would be covered, and continuous
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