RU744U1 - Nuclear reactor fuel element - Google Patents

Abstract

A nuclear reactor fuel element containing a zirconium alloy cladding, a fuel core with nuclear fuel, gas collection chambers and end parts, characterized in that the cladding is made of two coaxial, jointly rolled cylindrical tubes, and the inner and outer tubes have a wall thickness ratio of 1: ( 9 - 10) and coating their inner and outer surfaces, respectively, with pyrolytic chromium, and in the center of the fuel core there is a cylindrical rod made of metallic natural or depleted uranium, enclosed in a tube made of nuclear fuel cermet PuO2 + Zr or UO2 + Zr.

Description

TESHUSHD & SHSHDSH EGSHT DUAL REACTOR

The invention relates to the field of nuclear energy, in particular to the design of fuel elements (fuel elements) of nuclear reactors, and may be u) named for the design of water-water reactors without boiling water in them (VUR, VVRD, / and for boiling water - boiling water-water reactors (VNRK, etc.) and boiling uranium-graphite reactors of the RBJ type.

Known rod, lamellar, annular, crosswise, square, spherical and other complex cross-sectional shapes of the fuel rods for various types of nuclear reactors / I, 2 /. These fuel elements consist of a shell filled with nuclear fuel, end parts, spacing elements (ribbing or wire on the outer surface of the shell). Above and below, end parts are inserted into the shell. In the upper and lower parts of the fuel rod there is a compensation gap (gas collection chambers). As the material for the cladding of a fuel rod, stainless steel (thickness 0.4-0.5 mm) and more often zirconium alloy (Z.t jf) C5volshchsch. P, 65-0.95 mm) are used. For the manufacture of their fuel cores, w1% okb1 is used to modify ceramic fuel in the form of uranium dioxide tablets (0), dispersive nuclear fuel, for example,% l; refractory (), as well as cermets in the form of a mixture of 1 plutonium oxide (PuOj,} or uranium dioxide () in the mafsha of metal: nickel-1 la, stainless steel, schfkoniya, niobium. / d, 4/.- new disadvantages of such fuel rods with C / O fuel (in VVER, VVRD, RBMK, VVRK, etc.) are reduced radiation resistance at high temperatures, low density and thermal conductivity of the fuel, for example, UO - 8.5 -9.3 g / cm, reducing the campaign, reactor safety, mining burnout and economic indicators of a nuclear power plant (AH).

/ 5, 6 / Reactor lecAeAOBaHUfi twads with a barrier compound made of pure cirEonig shahazi they chiachuyuchat radiation resistance, increase the resource and burnout of toshva to 40000-50000 IW-day / T / due to the reduction of damage to TVMs due to the interaction of ropero. Therefore, it is reported that there is a method and tremendous technoligy for the production of zirconium pipes, which enables, through the external coaching of billets of zirconium bonded and pure zirconium, to produce pipes with thin zirconium olosha on the inner surface / 7 /. This construction of a twad with a zirconium barrier coating minimizes the interaction of lively tablets with a rim, the release of gaseous products of deduction (HCC) from it, and, consequently, the increase in the induced activity of tight work, increases the reliability of the solid, which will be taken into account in the design of the solid.

Known designs are sternevye tvzdov, in which milking a decrease in the interaction of tochiv with the rim. reduction of the formation of HCC in the fuel core is achieved by: n) naming the tablets 1/0 with a central hole; reduction of powder grains 1/0 to 80 μm with the addition of getters. 7, l, L; using compound (duplex) tablets / 8 /. The composite fuel tabetga (duplex tabetka) has an outer code of enriched and an inner part of pure or depleted uranium. Reactor tests of composite fuel pellets under blasting showed that the mechanical interaction of such a fuel with a shell means that even creep of linear power of the fuel is 650 W / cm. The reduced thermal expansion of such a divine provides a reduction in 1 Live and rim deformation. In this case, the maximum working temperature of the tablet and the output of the corrosive PG are reduced, which leads to an increase in the reliability of the fuel rod. All these results about these fuel rod designs will be taken into account when developing the fuel core design for the fuel rod.

Known is the rod fuel rod of the cicidric phase 11 of the BB3P-IOOO / 9 // water reactor from the rim, in which the fuel heart is made of nuclear fuel in the form of sintered uranium dioxide tablets () with an affective density of 8-9 g / cm and a diameter 7.5 1Sh, gas collection chambers, plugs with suspensions. The rim with a diameter of 9 mm is made of zirconium

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soyaava (-i- 1/1) and has a thickness of 0.65 mi. Ueioor with a nylon and sheath having a sasop (thermocell layer) filled with helium under pressure. Osepixy and Oshu fuel core are preloaded by squads (puffs), located in the gas collector and provided with their support and the expansion of axial extensions. The gas-boilers are used to collect PS, formed in the fuel 1FI the work of the fuel elements in the nuclear reactor “Fuel pellets have a central hole 1.4 mm in diameter to remove PS I8 and, therefore, reduce gas swelling of the fuel element

The named design of the fuel rod is designed for water-water reactors. The fuel rod uses nuclear fuel in the form of uranium dioxide tablets (i) with an axial hole in the center, and for the shell - zirconium alloy (Zt i% //). The gap (thermal layer) between the fuel and the shell provides compensation for thermal expansion of the tablet, the minimum their effect and PG on the shell. Along with the well-known advantages, VOz has the following disadvantages: low heat conductivity and a high temperature gradient in it, low density (on average 8.5–9.3 g / sag) compared with other types of cuoco-temperature fuels, significant gas deposition and the accumulation of PG at operating temperatures (1000), which cause its gas swelling, formations, a tendency to collapse under the influence of thermal stresses in the fuel core, especially frequent variable operating conditions of the reactor, as well as interaction 0 with theta carrier, ryuyur, water, steam and others. sheath upon loss of tightness, which increases induced coolant activity and deteriorates the radiation conditions (PO) in the reactor room, etc. In addition to TBGO, the design of the fuel assembly in VVER allows to achieve a reproduction coefficient (SB) of 0.3-0.35, fuel burnup up to 25000-ZOShr MW-day / g. , and, therefore, the energy efficiency of fuel is reduced, and it does not make it possible to create a В8Р-razmozhetchitel, which generally reduces the efficiency of a nuclear reactor and nuclear power plant / 6 /. The fuel cladding and the fuel core, being the first barriers to the safety of the reactor, scrupulously increase the output of the PS and the interaction of nuclear fuel with the coolant. A significant temperature gradient in Og fuel pellets facilitates the migration of fission products and PG, for example, xenon, krypton increase thermal resistance

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Vavora, that increasing the data rate of these tablets. At the end of the PS, the primary) IMdr, iodine, cesium oxide corrode the shell. Thus, these factors reduce reliability, fuel rods as well as the safety of KB and the efficiency of the reactor, since they can lead to a violation of the sealed rim and to the interaction of the carrier with the carrier and the efficiency of the X-security safety barrier is reduced and the opportunity to create increased safety nuclear reactor providing one degree of risk 10 1 / year for the reactor and also WWR-distributor / 10 II /

The objective of the present invention is to increase the reliability of safety and the life of a fuel rod as well as to improve the physical and operational characteristics of a nuclear reactor.

The purpose of this invention is the elimination of these drawbacks to increase the resource and safety of a fuel rod burnout and energy efficiency of nuclear fuel efficiency of a reactor such as BBSiP.

According to the invention, in a fuel rod of a nuclear reactor containing a shell made of an alkali-carbon alloy, the fuel core with nuclear fuel has gas collection chambers and end parts, unlike the fuel rod of the prototype, the shell is made of coaxial, jointly plucked cylindrical tubes, the inner and outer tubes

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have THICKNESSES of walls 1 :() and their respective inner and outer surfaces are coated with pyrolytic chromium, and a cylindrical rod made of natural or depleted uranium metal enclosed in a tube of nuclear fuel cermet / + or

C / h-Zz:, jj increasing the reliability of a fuel rod by reducing the likelihood of nuclear fuel interacting with the heat carrier water or water, its shell is made of two coaxial cylindrical tubes, and the ratio of their thicknesses is equal to 1: (9-10) from the following considerations. this takes into account the thickness of the zirconium cladding of the fuel rods of the VVER and EBMK reactors component) 9 mm, which is the bearing and increasing pressure PS. It is rather difficult to produce an inner tube with a wall thickness less than w, for example by rolling. Therefore, from the point of view of achieving high strength of manufacturability and the ability to manufacture a coaxial shell, the optimum ratio of the wall thicknesses of the tubes is t e. 1: 9 or with a margin of 1:10 “This ratio, as shown by calculations and laboratory tests, is too big because strength

Some of the boiling casings are overexposed to the practical cerebral cysts, mainly of the outer casing. Calculation of the coaxial casing is carried out on u) accuracy of the thickness of the tubes. The sheath reliability is ensured by a double stand, which could be used in tubes of different thicknesses, but this is uneconomical, because the strength of the combined shell will always be determined practically by the strength of the broken shell. Thus, calculations and tests have shown that if the inner cladding of a fuel element is not suitable, then the PS will act on the outer cladding, which, for example, if it is 2 times thinner than the thickness of the ddh shells, will be tinted nasche) anion is about 2 times higher. This is not feasible and, therefore, it is impossible to increase the thickness of the coaxial membrane by 2 times. In addition, if the cladding of the fuel element is nailed, then the pressure of the load carrier and the hydraulic control valve will be two tubes (shells) - internal and external. If both cladding of fuel elements are leakproof in one and the same way. 1 jse that this is probable, then, depending on the size of the defect, both claddings of the fuel cladding can work only on the outside. But 1 of the targets for getting the heat transfer agent into the fuel line and its interaction with the nuclear fuel is so short that practically no radioactive contamination of the primary coolant, deterioration of the environmental friendliness of the nuclear power plant, and damaging fuel assemblies, for example, I’m going to be removed from the core. It means that it is advisable to lay like a mind-blowing greater ratio of the thicknesses of the two tubes, Oushchako, from the point of view of manufacturability, economy, and even the parasitic absorption of neutrons, and, consequently, the physical characteristics of the reactor, the coaxial shell must be manufactured with 01b minimal ratio of the wall thicknesses of the inner and tubes l (), Thus, the requirements for environmental friendliness and safety of the i fuel element; As the first barrier to the safety of the reactor and the gas station as a whole, they can be satisfied with the proposed piston rod - the use of the coaxial sheath of a fuel rod, consisting of internal and broken tubes. Along with this, the cladding of the fuel cladding was made with a pyrolytic lame thickness of up to 2G-3QW / 12 /: the inner surface of the second shell (tube) in contact with the nuclear Q-gsn M with the elbow is a barrier layer and prevents possible contact with the cladding the corrosive effects of volatile HYDs, e.g., Iodine, cesium during reactor operation; narrai of the surface of the first shell (grzgbkg) providing an increase in its corro - S 32 / zioenoy oyohihfi in tbvyaonosifelv, wahfshmr water ihn var. The% design of the fuel core consists of DaewooZ - the central rod of a cylindrical fusion of natural or depleted (dump) metal uranium (a bucket component) and an outer cylindrical tube of nuclear fuel cermet of plutonium dioxide (Rio) or uranium dioxide C) in a matrix of zirconium () / or / (bivalent component) into which the rod is placed. This consistent fuel core allows | K to obtain such high nuclear bitter agmeters as an effective density of 12-15 r / oir, which is beneficial because of the use of uranium metal (without such fuel clannishness is practically unattainable) and thermal conductivity, which reduces its maximum temperature , temperature gradient over the cross section of the dump and the yield of active HCD. This improves the working conditions of the fuel element, its radiation resistance, and also reduces the tendency to destruction under the influence of thermal stresses. A fuel rod with such a nuclear fuel, with an effective density of 12-15 g / sag makes it possible to create a promising WWZR multiplier with improved energy use of fuel, in which, according to calculations, KB 1,2 1.2-1.3 is achieved, which increases the cost-effectiveness of a nuclear reactor . In addition, the use of high-temperature cermet Pt 0 + Z or -i- 2t: in the form of a cylindrical stake tube, for example, 0.8-1.5 m thick, in which ceramic fuel / or io (fissile component) is dispersed in a zirconium matrix, can significantly reduce the known shortcomings of ionizing agents and / and minimizing the formation of AH aa due to their localization in the matrix and fuel to: which reduces the swelling of the fuel, its interaction with the cladding, the gas activity of the coolant and, therefore, the reliability, safety, fuel resource and you fuel burning can be achieved over 50,000-60000 | Units per day / g. i. In this case, the optimal values of the geometrical sizes of the kettle tube (thickness, diameter, etc.), the amounts of enriched uranium or plutonium in the fuel are determined as a result of the process of physical analysis of the reactor and the technology of its production by extrusion methods. Thus, in order to prevent the core of the fuel core material from water or chrome in the emergency caqriae, to prevent the shell from failing, the fuel element of the proposed fuel element design is sealed for its part made of metal uranium, which has low compatibility with water and steam, the coaxial shell J: 3o3

and an ingot tube from Tomsk Kerst. atom significantly reduces the likelihood of the interaction of a fuel carrier with nuclear fuel, especially with mdtaddy hot uranium, even if the outer cladding of the fuel element is depressurized "which increases the safety of the reactor fuel rod, the radio frequency and environmental safety of nuclear power plants. The indicated technical solutions should be taken together, and not separately, KOTojaie may be known, because it is etv and the total effect that make it possible to achieve the goals and objectives of the invention. The inventive step of the proposed fuel rod design is confirmed by the fact that a combination of essential distinguishing features allows to obtain a load of properties, namely, to produce TV9L with perfect safety, resource, fuel burnout, providing the possibility of creating NER-multiplied. The analysis of the current level of technology showed that on the filing date of the application u) the technical solutions put forward are new. Signs that distinguish the underlying technical solution from the | 1rototype are not included in other technical solutions when studying this and related areas of technology. Therefore, the claimed invention has an inventive step.

In the drawing shown Shch) monolithic (figD) and transverse (Fig.2) sections of the rod Fewal cylindrical. A fuel rod consists of end parts I, a coaxial shell of zirconium alloy (- IJ2 L) - an outer tube 2, an inner tube 3, a fuel core that includes a tube 4 of cermet / h-7g or 2 + Z (fissile component), which is enclosed rod 5 of metallic uranium or depleted (dump) uranium (producing a series of xyuent). The fuel core is drawn up from below and above by springs (wads) 6, abutting against the plugs 7 of the core, which provides freedom of thermal expansion of nuclear fuel, improves the conditions for transporting a fuel rod. A contact (thermal) layer (gap) 8 filled with helium is provided between the uranium rod and the cermet tube. To collect the ISH generated during the operation of the reactor, gas collection chambers 9 are provided, in which the springs 6 are placed.

Assembling a fuel element, for example, with an external diameter of 13.6 mm, is carried out using pre-made coaxial casing 2, 3, a fusing core from a tube 4 and a rod 5, end parts I, plugs 7, springs 6. An oaxial casing, for example, of diameter 13, 6 mm has a thickness, as with existing fuel element designs, for example - 9

measures 0.5-1 w The inner tube 3 is thick up to OD w, the outer tube 2 is thick, 8 l) and the result is a joint cathode of these ducts. After that, I take a fuel core, consisting of two parts - a rod J made of natural metal FIR depleted uranium with a diameter of, for example, 9 w and a tube, nakhfimer, I mm thick from cermet / g or +, Weight fractions in the cermet of ceramic bitter I or UOs are up to 40-50, zirconium. The average active density of the fuel core is reached 12-15 g / cm. Then in

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coaxial shell Esuu., 3 install this fuel core from tube 4 and stub 5, plugs 7, u) suppers 6, end parts I, which are welded to the shell, for example, by electron beam welding.

The operation of the ta11 fuel rod, as well as other fuel rod designs, is closed in order to ensure, during their location in the reactor core, the fission reaction and the generation of thermal energy. During the operation of the reactor in the fuel elements, two main processes occur: fission of the nuclear fuel contained in them and radiation capture of neutrons in fuel and other structural materials. Laboratory technology was developed and a batch of such fuel elements was made for subsequent loop reactor tests. Preliminary studies show the possibility of solving the problem and achieving the goal. Therefore, thanks to the technical solution indicated, an increase in the resource, reliability, safety of fuel elements is achieved, and the reliability, safety and environmental friendliness of the nuclear reactor and nuclear power plant as a whole are increased accordingly. Thus, the proposed technical solution meets the criteria of novelty, inventive step and applied applicability.

The use of a federal design of a fuel element in a nuclear reactor, for example, of the WWER RBUK type, makes the probability of interaction of nuclear fuel with the coolant virtually zero and allows to achieve high fuel pacificity up to 15 g / cm, and, therefore, significantly increase the safety of the fuel element as the first reactor safety barrier, radiation safety and environmental friendliness of the AH, to increase reliability, fuel rod resource, burnout of toshshsh up to 55000-60000 MVTSut / g. d /, the reproduction factor to KB 1.2-1.3, to reduce the fuel consumption and improve its energy use, which improves the technical and economic performance of the reactor. Thus: the possibility of creating a promising

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a nuclear reactor with the highest environmental safety of a breeder reactor and the use of currently accumulated significant quantities of dump uranium.

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The authors:

rtj- f-- --- Z.A. Gorishni 3 N.N.Nikolaev

D.V. Gorishnyi 1 Formula of inventive technology for a nuclear rm shielding containing a shell of Y8 zirconium alloy, worn core with nuclear fuel, gas collection chambers and end parts, characterized in that the shell is made of two tubes renvia and the outer tube having a relative thickness of 1 wall thickness; (9-10) and covering them respectively with inner and outer surfaces with silver chrome, and in the center of the fuel core there is a stubble of cylindrical metal natural or depleted uranium, enclosed in a tube of nuclear fuel cermets, 1. Samoyloy AG and other Dispersion TVZLs, Volume 2, - M .: Energoatomizdat, 1982, p. 62-63; 223-224. 2. Frost B. Fuel elements of reactors, - N .: Energoatoiizdat, 1986, C.I75-23I; 36-37. 3.Kuznetsov V.A. et al. Marine nuclear power plants. - I .: Atomizdat, 197§, p. 104. 4.ZaImovsky A.S. et al. Thermal elements of nuclear reactors. - P .: Atomizdat, 1962, p.250 “252, 237, 241, 244-245. 5. Strasser A. World experience in the operation of fuel elements in light-water reactors. Nuclear Technology Abroad, 1986, L 9, pp. 20-23. 6.Burlakov V.V., Kalugin A.K. Thermal Neutron Fuel Cycles, Atomic Energy Series. Results of science and technology. - M .: aShKGI, 1984, volume 3, pp. 11-12; 11-25. 7.Nakrasova G.A., Vabiyaashvili Yu.Kh. Barrier Sheath Design in the USA. At tech. for rub., 1986, L. I, p. 3-9. 8. The influence of manufacturing technology on the operational characteristics of fuel elements of water-to-water reactors. IAEA Review, Express Information Based on Foreign Press. - M.: CEIIATOMIN ORN, L 49 (II77), 1987, pp. 7-9. 9.Budov V.M., Farafonov V.A. Design of the main equipment of nuclear power plants. - M. Energoatomizddt, 1985, p.31-37. 0. Samoilov O.B. and others. Safety of nuclear power plants - M .; Ene: | syatomizdat, 1989, p. 16-23. Sources of in $ o | ma1shchi

Claims (1)

A fuel element of a nuclear reactor containing a zirconium alloy shell, a nuclear fuel core, gas collection chambers and end parts, characterized in that the shell is made of two coaxial, jointly rolled cylindrical tubes, the inner and outer tubes having a wall thickness ratio of 1: ( 9 - 10) and coating their respective inner and outer surfaces with pyrolytic chromium, and a cylindrical rod made of metallic natural silt is installed in the center of the fuel core depleted uranium, enclosed in a tube of a nuclear fuel cermet PuO2 + Zr or UO2 + Zr.