The SP- 100 Program is developing a nuclear reactor power system that can enhance and/or enable future civilian and military space missions. In addition, a series of lithium thaw characterization tests has been performed, confirming key design assumptions.Ĭox, Carl. System thaw/startup analysis has confirmed that all system thaw requirements are met, and that rethaw and restart can be easily accomplished with this design. The thaw design has been established for the 100 kWe SP- 100 Space Reactor Power System. SP- 100 lithium thaw design, analysis, and testingĬhoe, Hwang Schrag, Michael R. Design emphasis is on performance, safety, long life, and operational flexibility. For this system, the reactor is emplaced in a lunar regolith excavation to provide man-rated shielding, and the Brayton engines and radiators are mounted on the lunar surface and extend radially from the central reactor. This system capitalizes on experience gained from operating the initial 100-kWe module and incorporates some technology improvements. The second design combines Brayton conversion with the SP- 100 reactor in a erectable 550-kWe powerplant concept intended to satisfy later-phase lunar base power requirements. Design emphasis is on ease of deployment, safety, and reliability, while utilizing relatively near-term technology. Man-rated radiation protection is provided by an integral multilayer, cylindrical lithium hydride/tungsten (LiH/W) shield encircling the reactor vessel. This system is intended to meet early lunar mission power needs while minimizing on-site installation requirements. The first design integrates a 100-kWe SP- 100 Brayton power system with a lunar lander. Two designs were characterized and modeled. Mansfield, Brian C.Įxamined here is the potential for integrating Brayton-cycle power conversion with the SP- 100 reactor for lunar surface power system applications. The bomb was made in the form of a sphere with pieces of plutonium, each below the critical mass, at the edge of the sphere.SP- 100 reactor with Brayton conversion for lunar surface applications Therefore, scientists developed a plutonium-239 bomb because Pu-239 is more fissionable than U-235 and thus requires a smaller critical mass. When one piece in the form of a bullet is fired into the second piece, the critical mass is exceeded and a chain reaction is produced.Īn important obstacle to the U-235 bomb is the production of a critical mass of fissionable material. The original design required two pieces of U-235 below the critical mass. When the critical mass reaches a point at which the chain reaction becomes self-sustaining, this is a condition known as criticality. The minimum mass needed for the chain reaction to occur is called the critical mass. In addition, the uranium sample must be massive enough so a typical neutron is more likely to induce fission than it is to escape. To produce a controlled, sustainable chain reaction, the percentage of U-235 must be increased to about \(50\%\). (These discoveries were taking place in the years just prior to the Second World War and many of the European physicists involved in these discoveries came from countries that were being overrun.) Natural uranium contains \(99.3\%\) U-238 and only \(0.7\%\) U-235, and does not produce a chain reaction. The possibility of a chain reaction in uranium, with its extremely large energy release, led nuclear scientists to conceive of making a bomb-an atomic bomb. Control energy production in a nuclear reactor. View a simulation on nuclear fission to start a chain reaction, or introduce nonradioactive isotopes to prevent one. The energy released in this process can be used to produce electricity. \): In a U-235 fission chain reaction, the fission of the m nucleus produces high-energy neutrons that go on to split more nuclei.
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