Abstract: In a high-temperature gas-cooled nuclear reactor system, which is suitable for modular utilization in combination with one or more other similar nuclear reactor systems, an arrangement which comprises passive heat sink means for absorbing decay heat energy generated at a reactor core included within said reactor system; and means for removing heat energy from said heat sink means at a rate sufficient to maintain the capacity of the heat sink means for absorption of decay heat energy such that release of fission products resulting from loss of forced circulation of gas coolant, or such loss in combination with coolant depressurization, when the reactor is critical and at power is prevented, thereby to provide safety means independent of human or automatic activation; and method embodiments corresponding to same.

Abstract: An improved gas circulator for a gas-cooled nuclear reactor system is disclosed which includes a stator, a rotor having a rotor shaft, and an impeller attached to one end thereof. A radial active magnetic bearing and a radial backup bearing are positioned proximate each end of the rotor shaft. An axial active magnetic bearing is also located between the ends of the rotor shaft, as is an axial backup bearing, with two of the backup bearings enclosed within a sealed chamber that may contain a lubricant, for example, a solid lubricant or a liquid lubricant. Preferably, the gas circulator is installed in a nuclear reactor system with the rotor shaft in a substantially vertical orientation and the sealed chamber near the bottom of the rotor shaft. The lower radical backup bearing and the axial backup bearing are advantageously located within the sealed chamber.

Abstract: An apparatus for consolidating spent fuel rods from spent fuel assemblies includes a container with a bottom and front, back, and side walls. The container has a plurality of flutes positioned adjacent to the front wall, and the plurality of flutes defines a plurality of channels. The apparatus also includes a plurality of springs, which are mounted on a support. The springs bear against the flutes and the channels when no fuel rods have been inserted into the container and the support is located proximate the front wall. The springs assist in guiding a fuel rod into a preselected location in the container; the springs are capable of maintaining the fuel rod in the preselected location. Preferably, each spring is a resilient finger that extends outwardly from the support toward the front wall. The support may be a movable sheet. The apparatus advantageously includes a device for moving the support. Such a device may automatically position the support in response to control signals.

Abstract: A system for consolidating spent fuel rods from spent fuel assemblies includes an operator and control station, a fuel rod transfer tool with a gripper assembly, indexing devices, and a fuel consolidation station. The fuel rod transfer tool and gripper assembly grips a fuel rod and withdraws it from a fuel bundle until it is clear of the bundle. The tool, with the fuel rod drawn up inside it, is moved to another location where it is desired to place the fuel rod; the tool inserts the rod, and the gripper releases it. The fuel consolidation station has a frame that holds two fuel assemblies and a consolidation container. The bottom of the frame rests on the floor of the fuel pool. The top of the frame supports the indexing devices. An indexing device is provided for each of the fuel assemblies and the consolidation container.

Abstract: A portable and collapsible radiation shielding device is provided for the protection of personnel and equipment from ionizing radiation. The shield has a plurality of horizontally elongated slats of radiation shielding material, such as lead wool, hung from a plurality of horizontally spaced apart chains at spaced intervals along the length of the chains. The slats are connected to the chains near their top edges so that when they are in their raised state the slats are suspended from the chains and arranged in an overlapping manner, like shingles, and when collapsed arrange themselves neatly side by side in a stack. The device also has a container adapted to receive the shield in its collapsed state, and a hoist and mast for raising and lowering the shield into and out of the container. The container further has wheels for facilitating moving the device to the desired location, and an outrigger for providing stability to the shield when raised.

Abstract: An ultrasonic decontamination robot removes radioactive contamination from the internal surface of the inlet and outlet headers, divider plate, tube sheet, and lower portions of tubes of a nuclear power plant steam generator. A programmable microprocessor controller guides the movement of a robotic arm mounted in the header manway. An ultrasonic transducer having a solvent delivery subsystem through which ultrasonic action is achieved is moved by the arm over the surfaces. A solvent recovery suction tube is positioned within the header to remove solvent therefrom while avoiding interference with the main robotic arm. The solvent composition, temperature, pressure, viscosity, and purity are controlled to optimize the ultrasonic scrubbing action. The ultrasonic transducer is controlled at a power density, frequency, and on-off mode cycle such as to optimize scrubbing action within the range of transducer-to-surface distance and solvent layer thickness selected for the particular conditions encountered.