Abstract: An apparatus for dismantling a radioactively contaminated tubular installation part which is located under water contains a base part which can be fixed to the installation part and in which a rolling cutting apparatus is mounted. The rolling cutting apparatus can be positioned in or on the installation part and has at least one cutting roller which can be moved to the inner or outer surface of the installation part and can be moved along it. The apparatus can be used to dismantle and remove even installation parts to which access is difficult, for example the cyclones which are installed in the water/steam separator of a boiling water reactor.

Abstract: In a computer modeling method for the core of a nuclear reactor the core is divided into a plurality of primary grids in the form of coarse mesh cells. A sub-section of the core relating to at least one grid is assigned to that grid. The sub-section includes that grid and a buffer zone that surrounds the grid horizontally and contains at least the grid that lies immediately adjacent to the first grid. The sub-section is sub-divided into a plurality of secondary grids—fine mesh cells—that are smaller than the primary grids. In a first computing step, a model of the core is calculated using a nodal calculation method, based on a respective dataset that is assigned to each primary grid. In a second computing step, a respective second dataset is assigned to each secondary grid of a sub-section and a model is then calculated for the sub-section, based on the dataset and the flows on the border of the sub-section that have been calculated in the first computing step.

Abstract: A fuel element for a nuclear reactor has a fuel rod bundle, at least one spacer with cells defined by at least one web section made from a first material and several guide tubes each running through a cell and axially fixed thereto made from a second material. The first and second materials have differing thermal expansion coefficients. The connection between the guide tube and the spacer is embodied as follows: first and second projections are directly or indirectly fixed to the guide tube. The first projections are disposed in a first axial position and the second projections are arranged at a second axial position and the projections each engage in an opening through the web section to give an axially-acting undercut.

Abstract: A fuel element for a pressurized water reactor has fuel rods guided through a number of axially spaced spacers. The spacers form a square grid with mesh openings arranged in rows and columns. Support tubes that do not contain fuel pass through a number of the mesh holes and are joined to the meshes . The support tubes are spread out in positions within the grid with a predetermined number of support tubes and a distribution thereof within the grid, which is rotationally symmetric about 90° with regard to a rotation about the central axis of the spacer, the central axis is perpendicular to the grid plane, the number of rows and columns that do not contain any support tubes is minimal. Optionally, remaining inner rows and columns that do not contain any support tubes are not situated next to one another.

Abstract: A spacer for a fuel element of a boiling water reactor contains cells that are formed by inner partitions, which are disposed in a crisscross manner, and by outer partitions, which surround the inner partitions in a frame-like manner. A guiding device is placed on the spacer and contains a flow-through opening, which is located in an outer partition. The guiding device also contains a guiding element which, when viewed in the direction of flow of the coolant, is located in front of the flow-through opening, and is situated at a distance from the inner side of the outer partition, and interacts with the flow-through opening like a venturi nozzle.

Abstract: A spacer for a fuel assembly for a light water nuclear reactor contains a plurality of intercrossed segments, which form a grid. The segments are formed from first and second metal strips which are assembled and provided with protruding parts or corrugations in such a way that the adjacent protruding parts are embodied in such a way that a flow component perpendicular to a vertical central plane which extends between the metal strips is applied to cold water running out from the flow sub-channel.

Abstract: The invention relates to a method of decontaminating an oxide layer-comprising surface of a component or a system of a nuclear facility, wherein the oxide layer is treated with gaseous nitrogen oxide (NOx) as oxidizing agent.

Abstract: An aligning device for fuel elements allows fuel elements of a pressurized water reactor to be aligned in a comparatively easy and quick manner. To this end, the aligning device for fuel elements includes an aligning body, which extends in a longitudinal direction and whose lateral faces formed from side metal sheets can be displaced out of a position of rest in a direction that is perpendicular to the longitudinal direction. The cross-sectional dimensions of the lateral faces of the aligning body in the position of rest are selected so that they are less than the corresponding cross-sectional dimension of a reference fuel element by a predetermined nominal value.

Abstract: A pump unit for a nuclear installation, for example a pressurized water reactor, contains a vertical shaft, which is guided through at least one journal bearing. The journal bearing or bearings is or are configured as a spiral groove bearing or bearings, to prevent shaft vibration caused by the bearings and to increase the service life of the pump unit. Preferred uses of the pump units include, for example, the coolant pump of a pressurized water reactor and the circulating pump of a boiling water reactor.

Abstract: A fuel assembly for a pressurized water nuclear reactor includes a multiplicity of fuel rods which extend in a longitudinal direction and are guided in a plurality of spacers that are spaced apart from one another axially. The spacers of an upper region have a lower flow resistance in a transverse direction perpendicular to the longitudinal direction, than the spacers of a lower region.

Abstract: A method of purifying water in a nuclear installation includes an ion exchange mechanism in which the water is purified with an ion exchanger. Before being guided over the ion exchanger, the water is brought into contact with a catalyst in order to decompose hydrogen peroxide that is present in the water.

Abstract: A pipeline configuration for the transport of a liquid, especially petroleum, contains a pipeline laid above ground, beneath which is disposed a sensor line for detection of a leak, extending along the pipeline in its longitudinal direction. The sensor line is disposed in a catchment container, fixed to the pipeline and likewise extending along it, at its lowest point. The catchment container has side edges running in the longitudinal direction and have a spacing from the outer surface of the pipeline. Inside the catchment container a device is disposed to reduce an air flow moving between the catchment container and the outer surface of the pipeline transversely to its longitudinal direction.

Abstract: A pressure vessel of a reactor has a flow space between the reactor core and a separation device for separating water from water steam. The cross-section area of the flow section of the space expands upstream of the separation device. This makes it possible to pre-separate a water-water steam mixture coming from the reactor core. Due to the pre-separation, only the central area is provided with a cyclone device, and only drying equipment is disposed near the cyclone device. The novel approach makes it possible to reduce the height of the pressure vessel of a reactor.

Abstract: A collector line for leakage monitoring and leakage location at a plant includes a carrier tube having a wall with openings formed therein, which are sealed with silicone rubber. This makes it possible to use the collector line during low ambient temperatures. A device and a method for leakage monitoring and leakage location and a pipeline having a collector line, are also provided.

Abstract: A fuel assembly for a light water reactor contains a fuel rod cluster and a spacer that has a number of cells, bounded by webs for laterally holding fuel rods. A damaged region including at least one damaged cell is present in an edge region of a spacer. There being fastened above or below the damaged region on the spacer with the aid of at least one connecting part is a replacement assembly that contains at least a number of cells that corresponds to the number of the damaged cells, at least a portion of the cells being traversed by fuel rods. A method for repairing the light water reactor fuel assembly in the case of which fixed above or below the damaged region on the spacer is a replacement assembly that takes over the holding function at least of one defective cell.

Abstract: A method produces a welded connection between first and second components each having inner and outer sides interconnected by an end face. The first component has a ferritic basic body carrying a plating at the inside and having an end face with a buffer layer of Ni-based alloy. The second component is of austenitic material. The end faces of the components enclose a weld groove. An austenitic root, connecting the plating to the end face of the second component, is welded in the weld groove. An intermediate layer of a nickel alloy having at least 90% nickel is welded onto the root. The intermediate layer is connected to the end faces of the plating and the second component. A weld seam is then produced in the remaining weld groove using a nickel-based welding additive. A method for repairing a welded connection between first and second components is also provided.

Abstract: An assembly for monitoring and locating leaks in an installation includes a collecting line formed of a material that is impermeable to a substance to be monitored. The collecting line has a multiplicity of openings spaced apart in its longitudinal direction. The openings are closed with a filter element of a sintered metallic material that is permeable to the substance and has been subjected to a heat treatment in an oxidizing atmosphere.