Abstract: A fuel channel for a nuclear power boiling water reactor is configured to include a bundle of fuel rods with nuclear fuel. The fuel channel is made of a sheet material and has a plurality of sides which have an elongated shape and which are connected to each other such that a corner with an elongated shape is formed where two adjacent sides meet. In one or more corners, the sheet materials from the two adjacent sides overlap with each other such that there is a corner region with double sheet material consisting of the overlapping sheet material from one of the two sides and the overlapping sheet material from the other of the two sides.

Abstract: The invention concerns a control rod configured for a nuclear power light water reactor of the BWR or PWR kind. The control rod contains absorber material. At least 50%, with respect to weight, of the absorber material that is in the control rod is in the form of hafnium hydride. The invention also concerns the use of such a control rod during operation in a nuclear power light water reactor of the BWR or PWR kind.

Abstract: The present invention relates to an apparatus and a method for cleaning a nuclear fuel element in a liquid filled space. The fuel element comprises an inner space with an opening. The apparatus comprises a connecting element, which is adapted to be connected to a portion of the fuel element, which comprises said opening and flow means, which is adapted to create, at least during a part of a cleaning process of the fuel element, a liquid flow through inner space of the fuel element via said opening.

Abstract: A fuel assembly for a nuclear boiling water reactor is provided. The reactor comprises a plurality of such fuel assemblies and a plurality of control rods. Each control rod is insertable between the fuel assemblies. The fuel assembly has a longitudinal center axis and includes a plurality of elongated fuel rods and an elongated channel box. The channel box has inner sides, facing the fuel rods, and outer sides. Each inner and outer side has a longitudinal center line extending in parallel with the center axis and along the length of the channel box. A number of protrusions are distributed along the center line of at least two of the outer sides. The protrusions are configured to ensure a minimum distance between the outer side and an adjacent control rod and to enable the control rod to easily slide over and on top of the protrusions.

Abstract: The invention refers to a fuel assembly comprising a lower end structure, an upper end structure including a top nozzle (5), a plurality of fuel rods and a plurality of guide thimbles (3). The top nozzle includes a passageway and an annular groove (10) in said passageway. A sleeve (11) is provided for attaching the guide thimble (3) to the top nozzle (5). The sleeve has at least three slots (12) and includes at least three bulges (13). Each bulge (13) has two ends and extends between two of the slots (12). At least one of the ends of the bulge (13) extends to a position at a distance (d) from the respective slot (12). The invention also refers to a guide thimble device (9) for use in a fuel assembly.

Abstract: The invention relates to a final, ready to use, spacer grid for a nuclear boiling water reactor. The final spacer grid comprises: i) a spacer grid structure made of an alloy that has been formed and assembled such that it constitutes a spacer grid, and ii) an outer oxide coating on the surface of the spacer grid structure. Said alloy is a Ni base alloy that consists of the following: (table) The invention also relates to a method of manufacturing the final spacer grid according to the invention.

Abstract: The invention refers to a device and a method for handling a fuel assembly (3), which comprises a number of fuel rods extending between a lower part and an upper part of the fuel assembly, a debris filter located in the lower part of the fuel assembly and a casing surrounding the fuel rods. The device comprises a lifting device (15) for engaging, during a lifting operation, a fuel assembly located in a reactor vessel (1) and lifting the fuel assembly upwards and out from the reactor vessel. A conduit member is connected to the upper part of the fuel assembly. A pump (32) creates a flow of water through the conduit member and the fuel assembly during the lifting operation. The flow has such a size that possible debris particles contained in and/or immediately beneath the debris filter at least are retained in and/or immediately beneath the debris filter during the lifting operation.

Abstract: A spacer for holding fuel rods includes cells formed by a sleeve having an upper edge and a lower edge and a number of abutment surfaces. The lower edge has a wave shape with wave peaks aligned with a respective one of the abutment surfaces, and wave valleys located between two adjacent ones of the abutment surfaces. The upper edge has a wave shape with wave peaks, which are aligned with a respective one of the abutment surfaces, and wave valleys located between two adjacent ones of the abutment surfaces. Each of the abutment surfaces extend from a respective one of the wave peaks of the upper edge to a respective one of the wave peaks of the lower edge. The sleeves abut each other in the spacer along respective connection areas to make the abutment surfaces rotatable with respect to a center point of the connection area.

Abstract: A method of welding a fuel rod includes the following steps. An end plug and a cladding tube of the fuel rod are brought together to abut each other, and welded by applying a laser beam directed to a welding zone to melt material of the end plug and the cladding tube. The welding is sensed by sensing radiation within a first wavelength range, which includes the wavelength of the laser beam coming from reflections from the welding zone, sensing radiation within a second wavelength range different from the first wavelength range, which includes infrared radiation from melted material, and sensing radiation within a third wavelength range different from the first and second wavelength ranges, which includes radiation from plasma. The welding and melting of material is monitored by monitoring the sensed radiations.

Abstract: A device for submersibly cleaning surfaces inside a nuclear reactor includes a pump and a nozzle connected to said pump. The nozzle is arranged to face surfaces to be cleaned. The device includes cleaning means capable of removing debris on surfaces to be cleaned. The device includes adjustable flotation means, capable of adjusting the flotation capability of the device depending on a type of cleaning application.

Abstract: The invention concerns a method of monitoring the operation of a reactor of a nuclear plant. The reactor is operated at a given total reactor power during a normal fuel operation cycle. The radioactivity level in the off-gas stream is continuously measured to detect a possible release of fission gases from the fuel rods as a consequence of a fuel leakage due to a defect on the cladding of any of the fuel rods in any of the fuel assemblies. An instantaneous power distribution is regularly established in the core and a power distribution pattern over time is established based on the instantaneous power distributions. The release of fission gases and the established power distribution pattern are then combined and correlations between changes in the release of fission gases and in the power distribution pattern are observed in order to determine a position of the defect.

Abstract: The invention relates to a fuel component and a method for manufacturing of a fuel component. The fuel component is adapted to be used in fission reactors. The fuel component comprises a core consisting of a first material, and a layer consisting of a second material. The layer encloses at least partly the core. The first material comprises a fissile substance. The fuel component comprises an intermediate layer between the core and the layer. The intermediate layer has a material gradient that comprises a decrease of the concentration of the first material from the core to the layer and an increase of the concentration of the second material from the core to the layer.

Abstract: The invention concerns a method comprising measurement on a fuel channel (14) of fuel assemblies (8) for nuclear boiling water reactors. The method comprises that: the measurement is done by the use of a non-destructive inductive eddy current measurement method, the measurement is done on a fuel channel (14) which has been used at least a certain time during operation in the core of a nuclear boiling water reactor, the measurement is done when the fuel channel (14) is located in water, the measurement is done on different places on the fuel channel (14), wherein through the method at least the hydride content of the fuel channel (14) at said places is determined. The method can be used in order to find out how shadow corrosion from a neighboring control rod influences the properties of the fuel channel (14).

Abstract: A spacer for holding fuel rods includes cells formed by a sleeve having an upper edge and a lower edge and a number of abutment surfaces. The lower edge has a wave shape with wave peaks aligned with a respective one of the abutment surfaces, and wave valleys located between two adjacent ones of the abutment surfaces. The upper edge has a wave shape with wave peaks, which are aligned with a respective one of the abutment surfaces, and wave valleys located between two adjacent ones of the abutment surfaces. Each of the abutment surfaces extend from a respective one of the wave peaks of the upper edge to a respective one of the wave peaks of the lower edge. The sleeves abut each other in the spacer along respective connection areas to make the abutment surfaces rotatable with respect to a center point of the connection area.

Abstract: A method of operating a nuclear reactor is disclosed. The reactor (1) encloses a core having a plurality of fuel rods (9). Each fuel rod (9) includes a cladding and fuel pellets of a nuclear fuel. The fuel pellets are arranged in an inner space of the cladding leaving a free volume comprising an upper plenum, a lower plenum and a pellet-cladding gap. The reactor is operated at a normal power and a normal inlet sub-cooling during a normal state. The reactor is monitored for detecting a defect on the cladding of any of the fuel rods. The operation of the reactor is changed to a particular state after detecting such a defect. The particular state permits an increase of the free volume in the defect fuel rod. The reactor is operated at the particular state during a limited time period, after which the reactor is operated at the normal state.

Abstract: The present invention relates to a device designed to capture the detached particles from an object being processed by the tool. The device comprises an inlet opening to an internal space. The device comprises guiding means configured to lead particles, which is detached during a machining process, the inner space of the container via the inlet opening and the inner space comprises a first materials that has a consistency such that it has the ability to receive and retain detached particles, which are led into the inner space during the machining process.

Abstract: The invention refers to a fuel assembly comprising a lower end structure, an upper end structure including a top nozzle (5), a plurality of fuel rods and a plurality of guide thimbles (3). The top nozzle includes a passageway and an annular groove (10) in said passageway. A sleeve (11) is provided for attaching the guide thimble (3) to the top nozzle (5). The sleeve has at least three slots (12) and includes at least three bulges (13). Each bulge (13) has two ends and extends between two of the slots (12). At least one of the ends of the bulge (13) extends to a position at a distance (d) from the respective slot (12). The invention also refers to a guide thimble device (9) for use in a fuel assembly.

Abstract: The invention regards a neutron absorbing component (1) and a method for manufacturing a neutron absorbing component. The neutron absorbing component comprises a core (2) consisting of a first material, a layer (3) consisting of a second material. The layer encloses a least partly the core and is adapted to protect the core from an outer surrounding. The first material has a higher neutron absorption capability than the second material. The neutron absorbing component is manufactured by sintering in such a way that an intermediate layer (4) is formed between the core and the layer. The intermediate layer has a material gradient that comprises a decrease of the concentration of the first material from the core to the layer and an increase of the concentration of the second material from core to the layer.

Abstract: The invention concerns a control rod configured for a nuclear power light water reactor of the BWR or PWR kind. The control rod contains absorber material. At least 50%, with respect to weight, of the absorber material that is in the control rod is in the form of hafnium hydride. The invention also concerns the use of such a control rod during operation in a nuclear power light water reactor of the BWR or PWR kind.

Abstract: Reactor component adapted to be used in fission reactors comprising a core (2) consisting of a first material and a layer (3) consisting of a second material. The layer (3) encloses at least partly the core (2). The reactor component is characterized in that the component (1) comprises and intermediate layer (4) between the core (2) and the layer (3). The intermediate layer (4) has a material gradient that comprises a decrease of the concentration of the first material from the core (2) to the layer (3) and an increase of the concentration of the second material from the core (2) to the layer (3).