A fuel assembly of a nuclear reactor
(57) Abstract:The essence: a fuel Assembly of a nuclear reactor contains a hexagonal bundle of fuel elements placed along the height of the Assembly spacer grids, head and tail of the parts connected support elements. The supporting elements mounted on the height from the tail to the top spacer grid and have the form stamped angular plates of zirconium alloy, and are welded to the spacer bars and screws with a tail part. 4 Il. The invention relates to the field of nuclear energy, in particular for fuel assemblies of nuclear power reactors.The famous design of the fuel assemblies of a nuclear power reactor  contains a hexagonal bundle of fuel elements placed along the length of the Assembly spacer grids of the head and the tail part, the United hexagonal outer case.The presence of the cover provides the necessary strength and rigidity of the fuel Assembly, but it introduces spurious metal in the active zone and increases linear heat load of anise fuel elements per unit volume of the active zone), and increases the non-uniformity of energy deposition in the fuel Assembly.The famous design of the fuel assemblies  in which the outer cover has openings spaced throughout the height and width of the face of the cover or window height facets of the case.The presence of holes or Windows in the sides of the cover reduces the amount of parasitic metal in the core, however, does not reduce the linear heat load of the fuel element, and the non-uniformity of energy deposition in the fuel Assembly to be even bigger.Known design fuel Assembly of a nuclear reactor  contains a hexagonal bundle of fuel elements placed along the length of the Assembly spacer grids of the head and the tail part, the United guiding channels passing through the spacer grid. The outer cover is missing. In the guide channels move the rods-absorbers. The spacing between fuel assemblies is reduced, the uniformity of the heat dissipation Assembly and a linear load, the fuel rod is reduced.The referenced Assembly is more economical, however, the application of similar assemblies on the power units with VVER-1000 showed that on the third goleada, that a fuel Assembly loaded mechanically from the head part to prevent it from floating in the stream moving upward coolant. In addition, during operation of the reactor also appears thermomechanical loading design of the fuel Assembly from the fuel rod and guide channels through the spacer grid. Therefore, the rigidity of the specified design fuel Assembly was insufficient, which reduces the safety of nuclear reactor.Known fuel Assembly of a nuclear reactor  contains a hexagonal bundle of fuel elements placed along the height of the Assembly spacer grids, head and tail of the parts connected support elements placed in the corners of the Assembly.The disadvantage of the design is reduced efficiency because of the massive support elements on the periphery of the Assembly result in the need to remove a portion of the peripheral fuel elements. This increase also the non-uniformity of energy deposition in FA and increases linear heat load of the fuel element.The objective of the invention is to improve the safety of nuclear reactor by ensuring the rigidity of the fuel Assembly the fuel element.The solution provided by the fact that in the known fuel Assembly of a nuclear reactor containing a hexagonal bundle of fuel elements placed along the height of the Assembly spacer grids, head and tail of the parts connected support elements placed in the corners of the Assembly, the supporting elements made in the form established by the height of the Assembly from the tail to the top spacer grid stamped angular plates of zirconium alloy welded to the spacer bars and screws with a tail.In Fig. 1 shows a section of the proposed fuel Assembly of a nuclear reactor;
in Fig. 2 section a-a in Fig. 1;
in Fig. 3 node I in Fig. 1;
in Fig. 4 site II in Fig. 1.A fuel Assembly of a nuclear reactor contains a hexagonal bundle of fuel elements 1 placed along the height of the Assembly spacer grids 2 of zirconium alloy. Head 3 and the tail 4 parts, made of stainless steel, connected to the guide channels 5, made of zirconium alloy, and the head part 3 is spring-loaded relative to the channels 5. In the corners FA p is Tina 6 of zirconium alloy, with radiation resistance. Plate 6 are welded to the spacer grids 2 and 7 screws on the tail part 4. The screw 7 is now pin 8. The thickness of the rim spacer grid is reduced to accommodate the plate 6. Thus, the spacing between fuel assemblies remains the same.The proposed fuel Assembly operates as follows.When the reactor fuel Assembly is loaded mechanically from above in the axial direction by springs (not shown) to prevent its ascent in the stream moving upward coolant. In addition, when heating the entire structure to operating temperatures appears thermomechanical loading of a fuel Assembly from the fuel rod 1. Plate 6 together with the tail part 4 and the spacer grids 2 form a rigid frame, preventing deformation of the Assembly and, therefore, the guide channel 5. Absorbing rods (not shown) can move freely within the guide channel 5.Thus, the increased safety of a nuclear reactor, the efficiency of the fuel cycle. A fuel Assembly of a nuclear reactor containing a hexagonal bundle of fuel elements, various support elements, placed in the corners of the Assembly, characterized in that the supporting elements made in the form established by its height from the tail to the top spacer grid stamped angular plates of zirconium alloy welded to the spacer bars and screws with a tail part.
FIELD: nuclear power engineering; fuel rods for water-moderated water-cooled reactors.
SUBSTANCE: proposed fuel rod designed for use in water-cooled water-moderated power reactors such as type VVER-1000 reactor has fuel core disposed in cylindrical can. Outer diameter of fuel rod is chosen between 7.00 . 10-3 and 8.79 . 10-3m and fuel core diameter is between 5.82 . 10-3 and 7.32 . 10-3m and mass, between 0.93 and 1.52 kg, fuel core to fuel rod length ratio being between 0.9145 and 0.9483.
EFFECT: reduced linear heat loads and fuel rod depressurization probability, enlarged variation range of reactor power, optimal fuel utilization.
7 cl, 3 dwg
FIELD: nuclear power engineering; manufacture of fuel elements and their claddings.
SUBSTANCE: each weld of cladding and its plug are tested in facility equipped with units for clamping and revolving the claddings, scanning with carriage using weld inspection piezoelectric transducer and piezoelectric transducer for measuring wall thickness in measurement region, immersion bath, ultrasonic pulse generator, ultrasonic pulse receiver, microprocessor, analog-to-digital converter switch, and random-access memory.
EFFECT: enhanced quality of fuel elements and their operating reliability in reactor core.
1 cl, 1 dwg
FIELD: nuclear engineering, in particular, engineering of micro heat-exhausting elements for nuclear reactors.
SUBSTANCE: first layer of micro heat-exhausting element with four-layer protective cover is made of SiC-PyC composition with content of 1,0-10,0 % of mass of silicon carbide with thickness of layer equal to 0,02-0,2 of diameter of fuel micro-sphere, second layer is made of SiC-PyC composition with content of 20,0-45,0 % of mass of silicon carbide with thickness of layer equal to 0,03-0,40 diameter of fuel micro-sphere, third layer is made of silicon carbide, while fourth layer is made of titanium nitride with thickness equal to 0,01-0,08 of diameter of fuel micro-sphere.
EFFECT: increased exploitation resource of nuclear reactor due to increased corrosion resistance and radiation stability.
3 dwg, 1 tbl
FIELD: nuclear power engineering; nuclear reactor fuel microelements covered with four-layer shielding coating.
SUBSTANCE: proposed method involves sequential fluid-bed deposition of coating layers onto fuel microspheres. First low-density pyrocarbon layer is deposited by pyrolysis of acetylene and argon mixture of 50 volume percent concentration at temperature of 1450 °C. 85 - 95 % of second layer is deposited from high-density pyrocarbon by pyrolysis of acetylene and argon mixture of 40.0 - 43,0 volume percent concentration, and of propylene and argon mixture of 30.0 - 27.0 volume percent concentration at temperature of 1300 °C; 5 - 15 % of coating is deposited by pyrolysis of propylene and argon mixture of 5.0 - 10.0 volume percent concentration doped with 0.5 - 1. 5 volume percent of methyl trichlorosilane. Third layer of silicon carbide is deposited by pyrolysis of methyl trichlorosilane and argon mixture of 2.5 - 3.0 volume percent concentration in hydrogen-argon mixture at temperature of 1500 °C. Upon deposition this layer is treated with hydrogen at temperature of 1750 -1800 °C for 20 - 30 minutes. 90 - 95 % of fourth layer is deposited by pyrolysis of acetylene and argon mixture of 40.0 - 43.0 volume percent concentration and of argon and propylene mixture of 30.0 - 27.0 volume percent concentration at temperature of 1300 °C. Upon deposition of 90 - 95 % of fourth-layer pyrocarbon coating thickness 5 - 10 % of coating is deposited by pyrolysis of propylene and hydrogen mixture of 3.0 - 5.0 volume percent concentration.
EFFECT: enhanced service life of fuel microelements due to reduced damage probability during their manufacture and in service.
1 cl, 6 dwg, 1 tbl
SUBSTANCE: invention is designed for increasing operation parametres and life cycle of active zone of a reactor due to the maximum fuel burnup, improved reliability and operation safety of maintenance of nuclear power stations. Fuel element can of a fast reactor with liquid metal heat carrier includes a metal tube of vanadium alloy with titanium, chrome and unavoidable impurities. External and internal tube surfaces are coated with stainless ferrite steel. Vanadium alloy components are taken at a given ratio. In particular, titanium to chrome ratio lies within 2.2 to 1.8 range. Between vanadium alloy and stainless ferrite steel a 6-8 mcm thick transition layer of solid solution of vanadium alloy with stainless ferrite steel is formed.
EFFECT: improved radiation, corrosion and heat resistance and mechanical properties of fuel element can in a fast reactor with liquid metal heat carrier.
3 cl, 5 dwg
FIELD: physics, nuclear.
SUBSTANCE: invention relates to nuclear power engineering and specifically to methods of making cermet rods of fuel cores of fuel elements of nuclear reactors for different purposes. A workpiece is put into a container. Working medium in form of solid glass is put into the container and the container with the workpiece and the working medium is heated to pressing temperature. The container is put into a press mould and moulding force is applied by increasing pressure of the working medium while moving the moulding die. In the proposed method the working medium is in form of a briquette. The briquette is placed at the bottom of the container. The workpiece is put on top of the briquette. The container with the workpiece and the working medium is heated outside the press mould until the workpiece is immersed in the working medium.
EFFECT: reduced probability of formation of voids, transfer of pressure onto the moulded workpiece becomes more uniform, increased output of the suitable products.
FIELD: machine building.
SUBSTANCE: procedure consists in immersion of tubular casing of fuel rod into water electrolytic medium containing particles of iron oxide and in covering it at least partially with layer of iron oxide. Also, particles of iron oxide are produced by anode oxidising iron containing working electrode.
EFFECT: increased corrosion resistance of treated rod and its increased service life.
7 cl, 1 dwg
FIELD: physics, atomic power.
SUBSTANCE: invention relates to nuclear reactor fuel rods. Fuel rod cladding has an elliptical cross-section. Each nuclear fuel pellet along the longer axis of the cladding has a truncated elliptical shape, and the shorter axis of the pellet has the same length as the shorter axis of the cladding, minus the fitting gap j, wherein the difference in length of the longer axis of the cladding and the truncated longer axis of the pellet is much greater than said fitting gap j. The invention also relates to a method of making nuclear fuel pellets and a method of packing said pellets, which enables to form a fuel rod.
EFFECT: lower probability of deformation of fuel rod cladding and release of fission products into the coolant.
9 cl, 3 dwg
SUBSTANCE: invention relates to methods of determining compatibility of various types of nuclear fuel and structural materials. Method of testing for compatibility of nuclear fuel powder with fuel rod cladding material comprises diffusion annealing of nuclear fuel powder and fuel rod cladding pair. From material of fuel rod cladding is made crucible with a polished inner surface and lid, after which it is moulded into a powder with test fuel and fission products simulators and sealing crucible in an inert gas atmosphere, followed by annealing in temperature range of 600-1,000 °C. Testing is carried out using uranium alloy powders or uranium mononitride with particle size of 10-20 mcm. To produce crucible and cover method uses corrosion-resistant steel or zirconium alloys, and as imitators of chemically active fission products, iodine and/or caesium and/or tellurium.
EFFECT: technical result is reliable contact (adhesion) of fuel and structural materials, which increases reliability and information value of diffusion tests.
8 cl, 3 dwg
SUBSTANCE: welded assembly of fuel element comprises a jacket and a plug with collar made of high-chromium steel, connected by weld seam obtained by argon-arc welding.
EFFECT: increased reliability of sealing of the nuclear fuel elements due to obtaining of the high-quality welded joint of the jacket with plug without subsequent heat treatment of the weld seam, is achieved by forming of the ferritic phase in the weld metal by changing the design of the jacket-plug connection made of steel of ferritic-martensitic and ferritic classes in various combinations in accordance with required sizes of the assembly and weld seam elements.
4 cl, 4 dwg, 1 tbl, 4 ex
FIELD: nuclear power engineering.
SUBSTANCE: proposed fuel assembly affording supercritical neutron-physical state under normal operating conditions of nuclear reactor and subcritical state of fuel assembly during loss-of-coolant and boiling accident has vertical process channel accommodating fuel elements mounted on supporting blocks which are alternating with absorbing blocks of which at least some of them are provided with cavity communicating with process channel space and filled with absorber in the form of boron powder enriched by boron-10 isotope conveyed in emergency situations by boiling coolant into process channel. Some of absorbing blocks accommodate combustible absorber.
EFFECT: enhanced inherent ability of self-protection and safety of pressurized-tube reactors.
3 cl, 1 dwg
FIELD: nuclear power engineering; fuel assemblies of water-cooled reactors.
SUBSTANCE: proposed debris entrainment filter is made in the form of plate with holes formed as V-shaped slots organizing adjacent rows, slot length obeying dependence L ≥ 5 S; slots may be disposed in row in mirror image or row may be formed by alternating slot branches of adjacent rows.
EFFECT: ability of entrapping most fine particles without increasing fuel assembly pressure drop.
3 cl, 4 dwg
FIELD: nuclear power engineering; fuel compositions for nuclear-reactor fuel elements.
SUBSTANCE: can of desired size is filled with finely dispersed fuel and in addition with material forming solid matrix at temperature equal to or higher than fuel melting point. This can filled with finely dispersed fuel and material forming solid matrix is heated to temperature equal to or higher than fuel melting point is heated and cooled down.
EFFECT: enhanced fuel density and resistance to destruction at meltdown accidents.
7 cl, 2 dwg
FIELD: nuclear engineering; nuclear reactor fuel elements.
SUBSTANCE: proposed nuclear reactor fuel element has nuclear fuel filled can and plugs. The latter are attached to butt-ends of can through welded joint. One of joints is made by resistance-butt welding with plug deepened in can wall so that changed-structure region is formed in plug and can; greatest part extruded from metal-to-dross joint accommodating region with maximal structural changes is disposed on external side of weld to form graded can-to-plug joint. Inner-surface sections of can are supported on internal part of weld by plug surface formed in the course of its displacement. Changed-structure region of can is between butt-end of can and weld.
EFFECT: enhanced mechanical strength of structure and corrosion resistance of weld, improved hydraulic characteristics of fuel element.
4 cl, 2 dwg
FIELD: nuclear engineering; mechanical design of power reactor fuel elements.
SUBSTANCE: proposed nuclear reactor fuel element has can and plugs. Can is filled with nuclear fuel. Plugs are welded to can. One of welds is positioned first along coolant flow within reactor and is disposed under external surface of can so that plug is deepened into the latter. Can has external section and that welded into fuel element can. The latter section whose diameter is smaller than outer diameter of fuel-element can but greater than its inner diameter is terminated with external dross squeezed out of weld. External section of plug is disposed directly past weld. This plug section is made in the form of cylindrical member turning into conical end of diameter smaller than or equal to maximal diameter of fuel-element can but larger than diameter of plug section welded into can. External dross is disposed between butt-end of fuel-element can and butt-end surface of plug external section joining the latter with generating surface of section welded into can.
EFFECT: enhanced manufacturability and reduced pressure drop over reactor coolant flow.
2 cl, 3 dwg
FIELD: nuclear power engineering; power reactor fuel elements.
SUBSTANCE: proposed nuclear-reactor fuel element has can sealed with plugs to maintain atmosphere of desired composition therein and pelletized nuclear fuel of enriched uranium disposed within can. Pellets are provided with axial hole and are assembled in fuel column terminating on both ends with shields made of depleted uranium and held tight against fuel column and against one of plugs by means of lock. The latter is disposed in expansion volume of fuel element can. Surfaces of fuel column and shields adjoin inner surface of can in a spaced relation to the latter. Cylindrical pellets form shield. They have axial hole whose axial diameter amounts to 1.2-2.3 of that of pellet column hole. Hole between surface of shields and inner surface of pellets amounts to 1.0-1.3 of clearance between fuel column surface and inner surface of can.
EFFECT: facilitated manufacture of fuel elements, enhanced in-service safety of reactor core incorporating proposed fuel elements.
1 cl, 1 dwg
SUBSTANCE: fuel assembly of a nuclear reactor consists of batch of fuel elements and guide channels, installed in spacer grids, head section and end section. The spacer grids are joined together as well as with the end section by elements, located along the length of the fuel assembly. The end section consists of a bedplate and a support body joined together. On top of the bedplate there is an anti-vibration grid, consisting of cells joined together. The anti-vibration grid, bedplate and the support body are joined together by at least one fastening element.
EFFECT: longer lifespan of the fuel element and fuelling and increased burn up fraction of the fuel.
FIELD: power engineering.
SUBSTANCE: invention refers to nuclear engineering and namely to manufacture of fuel assemblies for nuclear reactor, mainly water-cooled power reactor of "ВВЭР-1000" type. Control device of spacer grid of nuclear reactor fuel assembly includes weighs with constant magnet installed on support surface, and fixed platform for spacer grid to be installed in magnetic field. Magnet is composed of separate magnetic cells of the size corresponding to the size of spacer grid cell and located in a staggered manner relative to each other in accordance with various orientation of poles on the plate. The latter is made from magnetically soft steel and is of the size corresponding to spacer grid size.
EFFECT: improving accuracy of finding a cell from foreign material of spacer grid owing to magnetic field stabilisation.
FIELD: power engineering.
SUBSTANCE: anti-debris filter of heat emanating assembly of nuclear reactor consists of two plates with straight parallel slots arranged with axial gap between them; while projections of slots to plane parallel to surface of plates cross preferably at direct angle creating projections of pass-through apertures for coolant. Half-apertures can be made additionally along perimeter of each plate. Also at least one bridge dividing the slot can be made on at least one plate of each slot for additional strength upgrading.
EFFECT: increased efficiency of coolant filtering.
4 cl, 2 dwg