Closed cycle MHD power generation system driven by nuclear reactor for space exploration
For deep space explorations, we have to develop high-efficiency, high-reliability and high-performance electric power generation system. In this paper, a closed cycle magnetohydrodynamic (CCMHD) power generation system directly driven by a nuclear fission reactor (NFR) was proposed and investigated. Output electric power level is multi-MWe. Particularly, influence of the number of compressor stages, the regenerator efficiency and the radiator temperature on total plant efficiency and on specific mass (kg/kWe) was analyzed. Proposed system was expected to provide over 55% of total plant efficiency with the radiator temperature of 300 K. The estimated specific mass was about 2/spl sim/3 (kg/kWe) for 2 MWe output and 1/spl sim/2 (kg/kWe) for output power over 3 MWe level.
Pin‐Type Gas Cooled Reactor for Nuclear Electric Propulsion
This paper describes a point design for a pin‐type Gas‐Cooled Reactor concept that uses a fuel pin design similar to the SP100 fuel pin. The Gas‐Cooled Reactor is designed to operate at 100 kWe for 7 years plus have a reduced power mode of 20% power for a duration of 5 years. The power system uses a gas‐cooled, UN‐fueled, pin‐type reactor to heat He/Xe gas that flows directly into a recuperated Brayton system to produce electricity. Heat is rejected to space via a thermal radiator that unfolds in space. The reactor contains approximately 154 kg of 93.15 % enriched UN in 313 fuel pins. The fuel is clad with rhenium‐lined Nb‐1Zr. The pressures vessel and ducting are cooled by the 900 K He/Xe gas inlet flow or by thermal radiation. This permits all pressure boundaries to be made of superalloy metals rather than refractory metals, which greatly reduces the cost and development schedule required by the project. The reactor contains sufficient rhenium (a neutron poison) to make the reactor subcritical under wat...
Euthanasia — again: “Letting die” is not in the patient's best interests: a case for active euthanasia
Recent discussions in the Journal on the subject of euthanasia have relied on intuitive appeals to distinctions traditionally considered to be morally relevant, such as the distinction between acts and omissions (or killing and letting die), or ordinary and extraordinary means of treatment. These discussions remained inconclusive. However, the question of euthanasia no longer remains inconclusive if one adopts the perspective suggested by the United States President's Commission for the Study of Ethical Problems in Medicine and Biomedical and Behavioral Research and by the World Medical Assembly – that a doctor should act in his or her patient's best interests. From this vantage point, it is argued, there will be instances when active euthanasia is the proper cause of action.