Abstract: A cladding tube, a fuel rod and a fuel assembly are disclosed. The cladding tube comprises a tubular base component having an outer surface and an inner surface defining an inner space of the cladding tube housing a pile of fuel pellets. The tubular base component is made of a Zr-based alloy. A coating is applied onto the outer surface for protecting the tubular base component from mechanical wear, oxidation and hydriding. The Zr-based alloy has the following composition: Zr=balance, Al=0-2 wt %, Ti=0-20 wt %, Sn=0-6 wt %, Fe=0-0.4 wt %, Nb=0-0.4 wt %, O=200-1800 wtppm, C=0-200 wtppm, Si=0-200 wtppm, and S=0-200 wtppm. The total amount of Al+Ti+Sn>2.5 wt % and ?28 wt %.

Abstract: A nuclear fuel cladding tube is described herein that includes a zirconium alloy tube having an outer wear and oxidation resistant ceramic coating selected from the group consisting of CrN, Cr2N, CrWN, CrZrN, and combinations thereof. The cladding may have an intermediate layer formed between the tube and the outer ceramic coating. The intermediate layer may be selected from the group consisting of Ta, W, Mo, Nb, and combinations thereof. Both the intermediate layer and the outer ceramic coating may be deposited by physical vapor deposition.

Abstract: A process is described that includes forming a metal alloy component having a pre-specified three dimensional geometry for use in a nuclear reactor by an additive manufacturing process followed by annealing the formed component at a first annealing temperature within the alpha temperature range of the phase diagram for the metal alloy. A second annealing step at a second annealing temperature lower than the first annealing temperature may be added. Alternatively, annealing may be at an annealing temperature in the alpha+beta temperature range of a phase diagram for the metal alloy, followed by a second anneal in the alpha temperature range of the phase diagram for the metal alloy.

Abstract: A uranium oxide fuel pellet having an inner region and an outer rim region about the inner region, and that the fuel pellet is cylindrical and the inner region and outer rim region are coaxial cylindrical regions. The outer rim region has an excess of oxygen in comparison to the inner region, wherein high burnup structure (HBS) formation will be suppressed or delayed. Preferably, the excess oxygen is obtained by a chemical treatment by immersing the pellet in hydrogen peroxide (H2O2) or potassium permanganate (KMnO4) in solution.

Abstract: A uranium oxide fuel pellet having an inner region and an outer rim region about the inner region, and that the fuel pellet is cylindrical and the inner region and outer rim region are coaxial cylindrical regions. The outer rim region has an excess of oxygen in comparison to the inner region , wherein high burnup structure (HBS) formation will be suppressed or delayed. Preferably, the excess oxygen is obtained by a chemical treatment by immersing the pellet in hydrogen peroxide (H2O2) or potassium permanganate (KMnO4) in solution.

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: A method for manufacturing a sheet metal for use in a boiling water nuclear reactor and such a sheet metal. The method includes providing a material of a zirconium alloy that includes zirconium, and whose main alloying materials include niobium. The material is annealed so that essentially all niobium containing secondary phase particles are transformed to ?-niobium particles.

Abstract: The invention concerns a method of producing a cladding tube for nuclear fuel for a nuclear boiling water reactor. According to the method, a tube is formed which comprises an outer cylindrical component (10) mainly containing zirconium and an inner cylindrical component (20) metallurgically bonded to the outer component (10), wherein also the inner component (20) at least mainly contains zirconium. The inner component (20) has a lower recrystallization temperature than the outer component (10). The cladding tube is final annealed at a temperature and during a time such that the inner component (20) substantially completely recrystallizes and such that the outer component (10) partly recrystallizes but to a lower extent than the inner component (20). The invention also concerns a cladding tube, a fuel assembly for a boiling water reactor as well as the use of a cladding tube.

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: In a nuclear fuel rod a cladding tube is provided having a closed inner space and manufactured from at least one of the materials in the group zirconium and a zirconium-based alloy, and a pile of nuclear fuel pellets arranged in the inner space in the cladding tube. The nuclear fuel pellets fill part of the inner space. A fill gas is arranged in the closed inner space to fill the rest of the inner space. The internal pressure of the fill gas in the nuclear fuel rod amounts to at least 2 bar (abs) or at least 10 bar (abs). The fill gas contains a proportion of inert gas a proportion of carbon monoxide that is greater than 3 volume percent of the fill gas or greater than 2 volume percent of the fill gas.

Abstract: A method for manufacturing a sheet metal for use in a boiling water nuclear reactor and such a sheet metal. The method includes providing a material of a zirconium alloy that includes zirconium, and whose main alloying materials include niobium. The material is annealed so that essentially all niobium containing secondary phase particles are transformed to ?-niobium particles.

Abstract: A reactor of a nuclear plant encloses a core having a plurality of fuel elements and a number of control rods. Each fuel element includes a plurality of fuel rods each including a cladding and nuclear fuel enclosed in an inner space of the cladding. Each control rod is insertable to and extractable from a respective position between or in respective fuel elements to influence the effect of the reactor. A method for operating the reactor includes operating the reactor at a normal effect during a normal state, monitoring the reactor for detecting a defect on the cladding of any fuel rod, reducing the effect of the reactor after the detection of a defect, operating the reactor during a particular state during a time period during which the reactor at least during a part time is operated at the reduced effect in relation to the normal effect, and extracting the inserted control rods after the time period for continuing operation of the reactor at substantially the normal state.

Abstract: A zirconium-based alloy, suitable for use in a corrosive environment, where it is subjected to increased radiation and comprises 0.5-1.6 percentage by weight Nb and 0.3-0.6 percentage by weight Fe. The alloy is characterised in that it comprises 0.5-0.85 percentage by weight Sn.

Abstract: The present invention relates to a component (1) comprising an element (2), which contains zirconium or a zirconium alloy and which has a surface (3) on which a corrosion protective layer (4) is formed, the oxide layer (4) comprising zirconium oxide. The component (1) is intended to be in an oxidising environment (6) and said oxide layer (4) has an outer surface (5) towards said oxidising environment (6). The element (2) comprises a layer (10), that borders said surface (3) and comprises hydrogen and at least one metal from the group of lanthanum elements and/or from the group platinum metals and/or yttrium which in its elemental form or as an oxide have the ability to effectively dissociate oxygen and H2O. The invention also relates to a method for manufacturing the component (1) and a nuclear facility comprising the component (1).

Abstract: In a nuclear fuel rod a cladding tube is provided having a closed inner space and manufactured from at least one of the materials in the group zirconium and a zirconium-based alloy, and a pile of nuclear fuel pellets arranged in the inner space in the cladding tube. The nuclear fuel pellets fill part of the inner space. A fill gas is arranged in the closed inner space to fill the rest of the inner space. The internal pressure of the fill gas in the nuclear fuel rod amounts to at least 2 bar (abs) or at least 10 bar (abs). The fill gas contains a proportion of inert gas a proportion of carbon monoxide that is greater than 3 volume percent of the fill gas or greater than 2 volume percent of the fill gas.

Abstract: The invention concerns a method of producing a cladding tube for nuclear fuel for a nuclear boiling water reactor. According to the method, a tube is formed which comprises an outer cylindrical component (10) mainly containing zirconium and an inner cylindrical component (20) metallurgically bonded to the outer component (10), wherein also the inner component (20) at least mainly contains zirconium. The inner component (20) has a lower recrystallization temperature than the outer component (10). The cladding tube is final annealed at a temperature and during a time such that the inner component (20) substantially completely recrystallizes and such that the outer component (10) partly recrystallizes but to a lower extent than the inner component (20). The invention also concerns a cladding tube, a fuel assembly for a boiling water reactor as well as the use of a cladding tube.

Abstract: The present invention relates to a component (1) comprising an element (2), which contains zirconium or a zirconium alloy and which has a surface (3) on which a corrosion protective layer (4) is formed, the oxide layer (4) comprising zirconium oxide. The component (1) is intended to be in an oxidising environment (6) and said oxide layer (4) has an outer surface (5) towards said oxidising environment (6). The element (2) comprises a layer (10), that borders said surface (3) and comprises hydrogen and at least one metal from the group of lanthanum elements and/or from the group platinum metals and/or yttrium which in its elemental form or as an oxide have the ability to effectively dissociate oxygen and H2O. The invention also relates to a method for manufacturing the component (1) and a nuclear facility comprising the component (1).