The way to protect the core elements from destruction
(57) Abstract:The invention relates to nuclear energy, namely technological ways of protecting the items in the active zones of nuclear reactors channel and frame type from destruction, and can be used to suppress the debris effect, fretting and local corrosion of the fuel elements (FE), fuel assemblies (FA), technological channels (TC). The technical result is achieved in that on the surface, or part of the surfaces of the fuel elements and/or assemblies, and/or TC cause the protective coating from a material with a hardness greater than the hardness of structural materials and their oxides contour of nuclear reactors. While on the surface put diamond-like coating. In addition, on the surface cause the carbides, nitrides or borides of metals. The surface may be diamond-like coating together with carbides, nitrides, borides of metals in various combinations. 3 C.p. f-crystals. The method relates to the protection of the items in the active zones of nuclear reactors channel and frame type from destruction as a result of corrosion and mechanical abrasion by applying protective coatings. First of all to improve rprovides elements (Fe) of the active zone of the majority of Russian nuclear reactors made of an alloy of zirconium, 1% niobium on foreign reactors of zircaloy. In addition to zirconium alloys are alloys of aluminum and steel. Basically it is enough plastic having a low hardness materials. The fuel elements are combined in the fuel assemblies (FA) with grid spacers, which are made of steel or an alloy of zirconium. During operation of the fuel assemblies of various mechanical contamination of coolant, appearing in the circuit in the installation or repair work (metal chips, wire, welded hail, etc), as well as dispersed particles resulting from the corrosion of structural materials (corrosion products harder than the base metal), deposited or get stuck in the area of grid spacers. The pollutants while in the area of grid spacers under the influence of the coolant flow perform oscillatory motion and mechanical impact on the surface of the fuel elements (Fe). This breaks the protective oxide film, intensifying corrosion processes, and is also a purely mechanical wear thin shell Fe - debris-effect.To solve this problem on a number of foreign reactors were installed mesh filters to remove mehanicheskaya (Strasser A. Experiments, Mechanisms and Management. 26-29 May 1992, Dimitrovgrad, Russia). Another solution measures are implemented to prevent contamination in the reactor when carrying out installation and maintenance work. Despite the implementation of these decisions, the main cause of the pressure loss of the fuel rods at the moment as foreign and Russian reactors is the debris effect. All activities aimed at reducing the probability of mechanical particles in the reactor core, but none of them solves the problem of combating the debris-effect in case of ingress of particles into the active zone and stuck them, usually in the spacer grid.In the operation of the Assembly may occur some deformation processes in places of contact of the fuel rods in the clamping area, primarily in the spacer grids. Under the influence of the coolant flow is vibration of the fuel rods, resulting in a realized fretting (Smirnov A. C. D. Markov Century polenak B. C. and other Research into the causes depressurization of regular fuel of VVER and RBMK. Scientific-technical seminar "Modernization, improvement and improving the reliability of nuclear fuel for RBMK" S. 39-48. 25-27 October of coolant, under the influence generated oxidants processes are local corrosion as fuel, and technological channels (TC). The resulting zirconium oxide together with the corrosion products of steel structures of the circulation path passing through the active zone, lead to mechanical abrasion of the protective oxide layer on the surface of the fuel element.These problems can be solved if to protect surfaces primarily membranes TVEL from abrasion under the influence of vibrations in the system shell Fe - dictaminara lattice (fretting corrosion) or in the system shell TVEL - mechanical particle stuck in the spacer grid (debris-effect), and there should be no contact of aggressive environment, which is the coolant when unrepressed radiolysis of water with the surface of the sheath of the fuel element.These 3 problems can be solved by applying on the surface of the core constructs, such as fuel elements, fuel assemblies and TC of the protective coating.There is a method of protection of fuel graphite block, made from a mixture of zirconium carbide, uranium carbide and graphite by coating of carbides of zirconium or niobium (U.S. Pat.RF 2066485, BI 25, 1996), but it pokrenuti - steel surfaces equipment contours nuclear reactor by applying a Nickel-phosphorus coating (prototype - authorship 1028091, BI 22, 1989 ), the coating has a hardness higher than the hardness of Zirconia, but this coating if the coating on the Zirconia surface has the disadvantage that it has with zirconium weak adhesion and irradiated at a neutron flux of Nickel forms of radioactive cobalt-58, which degrades the radiation environment of the reactor.The task on which the invention is directed, is the suppression of the debris-effect, fretting and local corrosion of the fuel elements, fuel assemblies and TC made of zirconium and its alloys, which ultimately will increase the reliability of a nuclear reactor by reducing the probability of destruction of the core elements due to corrosion and mechanical abrasion.For this method of protection of core elements, in particular of fuel elements, fuel assemblies and technological channels, from destruction, namely, that on the surface, or a portion of the surface of fuel elements, and/or fuel assemblies, and/or technological channels are coated with material which tori.On the surface of the diamond-like coating is applied.In addition, on the surface cause the carbides, nitrides or borides of metals.The surface may be diamond-like coating together with carbides, nitrides, borides of metals in various combinations.In order to achieve the objectives of the coating should have the following properties:
1 - hardness and wear resistance of the coating should be less than similar properties of particles that can appear in the loop;
2 is a cross - section of the neutron absorption of the coating material should be commensurate with the absorption of neutrons structural material of a fuel rod, fuel Assembly or TC, or the contribution to the absorption of neutrons of this coverage must be comparable with the absorption of neutrons oxide film of corrosion products present on the surface of the fuel elements and the other, provided that the coating material does not perform other functions, such as the alignment of the energy release at the height of the zone;
3 - the coating material should not be activated with the formation of long-lived radionuclides from the hard emission spectrum;
4 - the coating should have good adhesion to the material of the fuel elements, fuel assemblies or TC and not break down during the operate is of Arbidol, nitrides, borides of metals with high hardness.For comparison, we give the microhardness of zirconium, aluminum, steel microhardness of the proposed coatings (according to works:. Panchenko, E. C., Skakov Y. A., creamer B. I. In the book. Laboratory of metallography. Ed. by B., Lifshitz. Ed. Metallurgy, Moscow, 1965.Long D. I. , Olshansky, E. D., Ryazantsev E. P. Obtaining diamond-like carbon films and application. Conversion in mechanical engineering. 1999 vol.3-4 (34-35), S. 119-122. Baryshnikov, M. C., Dubrovin the Karelian Isthmus is the Generalization of the results of post-irradiation studies of uranium-zirconium fuel rods. Paper presented at the conference. RIAR, Dimitrovgrad, 2000).Material Microhardness kg/mm2< / BR>Aluminum cast - 37,0
Aluminum deformed 25,0
then annealed at 40oC for 4 h, unpolished
Steel 10, base metal - 161
Steel 45, base metal - 191
Steel EI - 825 - 965
Carbide zirconium - 2836 - 3480
The titanium carbide - 2850 - 3390
Tungsten carbide-zirconium - 2700 - 2733
Tungsten carbide - 3000 - 3400
The boron carbide - 3700
Carbide vanadium - 2400 - 2800
Bored titanium - 3400
Bored zirconium - 2200
The Nickel-phosphorus coating - 500 - 550
Diamond-like coating is BR>Diamond-like coating has good adhesion, high abrasion resistance, the film is not processed even with diamond paste, high surface quality. These coatings also have excellent chemical resistance, not react with acids and alkalis.To reduce internal stresses in the creation of a relatively thick diamond-like films (5-20 μm), it is advisable to make a joint application of diamond-like films with carbides, nitrides, borides of metals, for example, is highly compatible with diamond-like film of silicon carbide.The application of coatings with high hardness and corrosion resistance, and above all the application of diamond-like coatings, and borides, nitrides and carbides of metals will allow to solve problems of wear and corrosion of equipment and circuit elements of power plants and nuclear power plants. 1. The way to protect the core elements, in particular, fuel elements, fuel assemblies and technological channels from destruction, characterized in that on the surface or a portion of the surface of fuel elements, and/or fuel assemblies, and/or technological channels are coated with a material with mi the century2. The method according to p. 1, characterized in that on the surface of the diamond-like coating is applied.3. The method according to p. 1, characterized in that on the surface cause the carbides, nitrides or borides of metals.4. The method according to p. 1, characterized in that on the surface of the diamond-like coating is applied together with carbides, nitrides, borides of metals in various combinations.
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; tubular dispersed-core three-layer fuel elements.
SUBSTANCE: proposed method includes production of powder mixture, powder mixing in plasticizer environment, cold molding in core billet with plasticizer, thermal sintering, hot molding-calibration of fuel core, core placing in can made in the form of sleeve with annular slot, calibration, hot molding through die, and drawing; inner surface of external can of sleeve is provided with longitudinal bulges and outer surface bears bulge location marks; fuel core is provided with longitudinal flats and placed in sleeve taking care to align bulges of the latter with core flats; in the course of drawing marks are aligned on arbor ribs.
EFFECT: enhanced stability of active layer and can thickness in shaping polyhedral fuel elements.
1 cl, 4 dwg
FIELD: nuclear power engineering; manufacture of fuel elements for nuclear reactors.
SUBSTANCE: process line primarily used for manufacturing fuel elements for VVER-1000 and VVER-440 reactors has charged can weighing device built integral with can-and-plug assembly weighing device that determines net weight of charged can by internal components, box holding devices for discharging fuel pellets from rejected fuel element, destructive testing of helium pressure within can, and preparing specimens for metallographic inspection.
EFFECT: enlarged functional capabilities of line, improved quality of fuel elements, enhanced yield.
1 cl, 9 dwg
FIELD: nuclear engineering; manufacture of plate-type fuel elements.
SUBSTANCE: core for three-layer assembly that has sleeve, circular core, and plugs is provided with longitudinal bonds made of sleeve material and three-layer tube obtained upon joint hot extrusion and drawing is cut along bonds; segments obtained in the process are drawn through slit die.
EFFECT: reduced labor consumption due to reduced number of pre-heat rolling operations.
1 cl, 5 dwg
FIELD: fuel cells designed for use in gas-cooled nuclear reactor core.
SUBSTANCE: fuel cell 10 designed for use in gas-cooled nuclear reactor has assembly of two adjacent fuel plates 12a, 12b disposed relative to one another and shaped so that they form channels 14 for gaseous coolant flow. Fuel plates 12a, 12b incorporate elementary fissionable particles, better non-coated ones, implanted in metal matrix. Metal coating may be deposited on both ends of each plate 12a and 12b.
EFFECT: enlarged heat-transfer surface, enhanced power density per volume unit.
13 cl, 5 dwg, 1 tbl
FIELD: nuclear power engineering; production of heat-generating elements and heat-generating assemblies for research reactors.
SUBSTANCE: the invention is pertaining to the field of nuclear power engineering, in particular, to production of heat-generating elements (further - fuel elements) and the heat-generating assemblies (further - fuel elements assemblies) for research reactors using a low (less than 20 %) enriched nuclear material. The technical result of the invention is enhancement of production capabilities for upgrading the existing research reactors, the fissile regions of which differ in dimensions and forms, using the universal rod-shaped fuel element and the based on it fuel elements assembly. The fuel element is made in the form of a tubular sealed on its end faces by plugs shell made out of an aluminum alloy of 0.30 up to 0.45 mm thick with four distancing screw-type ribs on the outer surface. The diameter of a circumscribed circle of a fuel element cross section makes from 4.0 - 8.0 mm. Each rib protrudes above the shell from 0.4 up to 1,0 mm in height and is placed in the cross section plane at an angle of 90° to the neighboring rib and twisted in spiral with a step from 100 up to 400 mm, predominantly from 300 up to 340 m. Inside the shell there is a fuel core made out of a dispersive composition of uranium-containing particles and an aluminum alloy, in which a volumetric content of uranium-containing particles makes up to 45 %, the uranium-containing particles dimension makes from 63 up to 315 microns, and the shell and the core have a diffusion cohesion among themselves, formed at the fuel elements manufacture by the method of a joint extrusion through a forming array of a composite cylindrical blank consisting of the fuel element core, the plugs and the shell. On the basis of the aforesaid fuel element the versions of the heat-generating assemblies are developed for research reactors of different types with various geometrical forms of the fissile regions.
EFFECT: the invention ensures enhancement of production capabilities to upgrade the existing research reactors with different dimensions and forms of their fissile regions with the help of the universal rod-shaped fuel element and the based on it fuel elements assembly.
9 cl, 6 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