Patent Number: 043137954
Section: summary

BACKGROUND OF THE INVENTION This invention relates to a nuclear power plant that is designed with a component design and arrangement with safety as a primary criteria. In particular, the power plant is designed for on-site disposal and storage of nuclear wastes and incorporates a component power generating system that utilizes a solid state heat transfer means that is both safe and compact. In conventional nuclear power plants the reactor is utilized in conjunction with relatively standard steam generating systems for the production of electricity. However, the necessary heat exchangers required to insure isolation from contamination of the operating water for steam production are expensive, and subject to failure because of their size and high pressure for containment at high temperature. Furthermore, large cooling towers are required for condensing steam for recycling in the power loop. These requirements virtually dictate the large capital investment in stationary plants with all the attendant problems of on-site use and off-site disposal of nuclear wastes from spent fuels. Further, dismantling and disposal of such large plants is predicted to cost more than the initial cost of construction. It is a primary object of the devised nuclear power plant to provide a power generating plant that uses nuclear fuels in a safe manner by providing for the necessary heat transfer within the primary reactor containment vessel by means that prevents the possibility of radioactive contamination of the power generating driving medium and by providing for on-site disposal and storage of the spent fuels. Further, the preferred power generating system eliminates the necessity of conventional heat exchanger boilers and condenser apparatus with their attendant high capital costs. Because of the general undesirability of fission power as compared with the yet uncommercialized fusion power it is expected that nuclear power plants employing fission will ultimately be replaced by fusion plants and therefore such plants do not warrant the high attendant capital costs. By limiting the components which are subject to radioactive contamination and by designing a plant that is contemplated to be disassembled, overall costs and radiation dangers can be minimized. SUMMARY OF THE INVENTION The nuclear power plant of this invention is constructed with an elongated vertically oriented, high pressure containment vessel within which a nuclear reactor core is centrally located. The power plant design is particularly adapted for use with a bare core or fast breeder reactor contained in a molten sodium medium which comprises an extractor medium for extracting heat generated in the reactor core. The pressure vessel is formed with two chambers at each end: a lower disposal and storage chamber for containment of dumped cores of spent fuel and an upper heat transfer chamber for transfer of the heat generated by the nuclear reactor to the driving medium for the power generation. Within a central segment of the pressure vessel above the core is an array of solid state heat transfer conductors which comprise elongated thermally conductive rods. The rods are preferably fabricated from aluminum core in a, seamless iron tube casing, or other material depending in part on the temperature operating range of the reactor unit. The lower portions of the vertically oriented rods are immersed in the molten sodium or similar medium surrounding the reactor core. A seal and support gasket seals the central segment of the pressure vessel containing the molten heat extractor medium and supports the plurality of rods in a spaced array for efficient heat transfer. The upper portion of the pressure vessel comprises an isolated chamber free from contamination by the core reaction or extractor medium, which becomes radioactive on operation of the reactor. The conductive rods project into and largely fill the upper chamber to maximize the surface area for further transfer of the reactor generated heat to the power plant driving medium. The power plant preferably utilizes a superheated steam as the driving medium in a closed cycle without condensation to water. In this manner, purified steam is cycled through the upper chamber under pressure where it picks up substantial heat from the conductive rods for expansion through a multi-stage steam turbine it produces rotary power for driving a connected electrical generator. The expanded steam at the reduced temperature from the energy transformation is then partially condensed to a point where most or some of the latent heat is removed then compressed by a conventional gas compressor for cycle return to the upper chamber of the pressure vessel. For reasons of safety, only the top segment of the reactor pressure vessel and the power generating components are above ground. In this manner, any failure in these components will release only uncontaminated superheated steam to the atmosphere. Because of the relatively low operating pressures, the chance of failure is substantially reduced, also, low grade heat is put to use. The reactor and molten heat extractor medium surrounding the core are below ground to isolate any contamination on any possible failure. Since there are no high pressure boiler components in contact with the heat extractor medium, the possibility of failure is substantially reduced. Below the reactor is a lower pressure vessel chamber which forms a disposal dump for used cores. When the fuel is spent, a dump mechanism isolates the core and the immediately surrounding heat extractor medium and drops the material into the dump where it is retained for temporary storage. Depending on the contemplated length of temporary storage, alternate designs for the storage dump can be employed. The dump may include nuclear reaction inhibiting material, for example, material with neutron absorbing characteristics to reduce the possibility of radioactive emissions and to control a reacting core inadvertently introduced into the dump by a meltdown. The dump is designed to accomodate multiple expended cores for continued on-site storage. When filled, the lower portion of the pressure vessel defining the disposal dump can be sealed. The remaining portion of the pressure vessel can be deactivated or moved to an adjacent or new site along with the attendant power generating components. The conventional power generating components are easily detached and reused as they are without contamination. These and other features of the invention will become apparent from the detailed description of the preferred embodiment. Because of the compact size of the power plant it is suitable for use in marine applications by simple substitution of the electrical generator with mechanical propulsion means. In such application the core storage component can be reduced in size or eliminated. In such applications vertical orientation of the containment vessel may not be preferred.