Nuclear reactor fuel assembly

FIELD: nuclear power engineering.

SUBSTANCE: proposed fuel assembly primarily designed for use in nuclear power reactors VVER-1000 and VVER-440 has composite bottom spacer grid built of at least two parts identical with respect to disposition of holes and total thickness of component parts equal to height of circular collar on bottom plug of fuel element, and tubular channel hole diameter for bottom plugs equal to diameters of lower ends of bottom plugs; the latter are secured in holes of aligned parts of bottom spacer grid by shifting component parts of bottom spacer grid relative to each other, by locking bottom plugs on circular collar of bottom plugs between annular projections of upper and lower parts of bottom spacer grid, and by aligning flow holes of bottom spacer grid component parts. Component parts of bottom spacer grid are rigidly fixed upon their shifting to bottom nozzle of fuel assembly in case of nonseparable type of assembly and loosely attached upon their shifting to bottom nozzle in case of separable type of assembly.

EFFECT: enhanced reliability of fixing fuel element plugs in bottom grid holes of separable and nonseparable fuel assemblies, reduced labor consumption for manufacture and assembly.

1 cl, 3 dwg

 

The invention relates to atomic energy and can be used at the enterprises engaged in the manufacture of fuel assemblies (FA), mainly for nuclear power reactors of the VVER-1000, VVER-440.

Known fuel assemblies of a nuclear reactor comprising a bundle of fuel elements (cartridges), installed vertically in the frame assembled from grid spacers, mounted on the tubular channels, the shank and removable head (see U.S. patent No. 4687619, CL G 21 19/20, 1987). A disadvantage of the known fuel Assembly is a low level of technological design her head, characterized by an increased complexity of Assembly and repair beam Rods, Assembly-disassembly of the head itself.

Known fuel assemblies of a nuclear reactor comprising a bundle of fuel Rods mounted vertically in the frame assembled from grid spacers, mounted on the tubular channels, the shank and removable head (see Germany application No. 2845515, CL 21 With 3/04, 1979). A disadvantage of the known fuel assemblies are the low level of technology head design and low reliability of the connection, providing its release.

Known nuclear fuel assemblies of VVER-1000 reactor comprising a bundle of fuel Rods mounted in the frame of the grid spacers mounted on the tubular channels fastened together with the Fuel rod lower ends to nor is it the lattice, the shank and removable head, where each spacer grid assembled from individual curly cells welded together at the points and sealed the outside of the rim, each cell has an internal projections, durable tightness fixing passed through the cells, the Rods and forming channels for the passage of coolant between the fuel Rods and the walls of the cells, between cells and between the peripheral cells and the rim (see the book Bajamonti. Nuclear power reactors. M. Energoatomizdat, 1990, pages 41-45, figure 2.13. Fuel assemblies of WWER-1000). Known FA has the same disadvantages as the FA for U.S. patent No. 4687619 and Germany application No. 2845515, and design FA is non-separable, because the fuel Rods in the lower grille zaspirtovanny and fixed by welding.

Known fuel assemblies of a nuclear reactor comprising a bundle of fuel Rods mounted vertically in the frame of the grid spacers mounted on the tubular channels fastened together with the Fuel rod lower ends to the lower grille, a shank and a removable head, where each spacer grid assembled from individual curly cells welded together at the points and sealed the outside of the rim, each cell has an internal projections, durable tightness fixing passed through the cells, the Rods and forming channels for the passage of coolant between the fuel Rods and the walls of the cells, between the cells and between the peripheral cells and the rim, and fastening the lower plugs in the lower grille is made longitudinally dissected and reconstituted in opposite side parts of the lower plug (see Russian Federation patent RU 2079170, MPK G 21 C from 3/32 30.05.95,, publ. 10.05.97. A fuel Assembly of a nuclear reactor). In the fuel Assembly at the bottom of the plugs of the fuel Rods of the lower part before Assembly in FA pre-cut in the longitudinal direction into two equal parts, and when assembling the fuel Assembly these equal parts for the bottom end of the lower grille to throw in the hand, for example, setting them on a tapered mandrel. FA eliminates the disadvantages of the known FA in terms of complexity due to the exclusion of spontania Rods, automation fixing plugs of the fuel Rods in the lower grille and the possibility of replacement of fuel Rods, if this becomes necessary, i.e. the fuel assemblies can be called as a variant of the folding assemblies. However, it is not considered that the implementation of each stub advanced milling operations on the cut ends of the insert into two parts increases its cost of manufacture, the thickness of one portion is 1.5 mm, which does not exclude its bending, damage at the stage of manufacturing and transportation. During the pressing of a fuel rod through 15 grid spacers (TVEL VVER-1000) and lower sieves is at when assembling the fuel Assembly could be damaged dissected parts of the lower plug. Not be damaged dissected parts of the lower stub in the process of their precipitation on the mandrel. TVEL broken at least one part goes into the marriage. It is also possible separation dissected parts of the lower stub upward flow of coolant in the core of a nuclear reactor. In this case, cut off the flow of coolant part of the stub represent a danger to the safety of other fuel Rods, because when you hit them on the shell Fuel under high pressure coolant sheath of a fuel rod may collapse and nuclear fuel will contaminate the fluid.

It is known that nuclear reactors VVER-type work when the coolant temperature 270-330°and pressure of 10-20 MPa with a flow of coolant from the bottom up active zone (see Development, production and operation of fuel cell power reactors. Book 1, M, Energoatomizdat., 1995, page 14, §1.2), that does not preclude axial displacement in a fuel Assembly of a fuel rod from the bottom up and pushing him out of the holes on the bottom of the lattice. In addition, the diluted part of the lower plug of a fuel rod create additional resistance to the flow of fluid, unpredictable vibration of the fuel rod and it is possible destruction of the weld membrane of a fuel rod with the bottom bracket because zirconium is prone to corrosive corrosion resulting from fluctuations even at very low amplitudes (see IU Allergy zirconium. Translation from English. Publishing house of foreign literature. M., 1959, s).

Closest to the technical essence and the achieved effect is a fuel Assembly of a nuclear reactor comprising a bundle of fuel elements installed in the frame of the grid spacers mounted on the tubular channels fastened together with fuel elements of the lower plugs with o-ring grooves in the bottom grid with adapter, shank attached to the adapter lower grilles, a head secured to the upper ends of tubular channels, and the elements ensuring the fixation of the fuel elements in the lower grille (see Russian Federation patent RU 2174718, MPK7 G 21 C from 3/32 28.12.1992,, publ. 10.10.2001, a Fuel Assembly of a nuclear reactor).

In FA prototype in a fastening element for a fuel rod is polevka on the wall of the cell, which is in an annular band on the lower part of the lower stub.

FA - prototype eliminates the disadvantages of FA analogues, however, it is known that the VVER-1000 has 312 fuel Rods 18 of the guide channels and the Central tube, to secure them in the lower grill will need to perform 331 polevka, which is very time-consuming and not amenable to automation, because it is done manually. When performing three puklavec on each cell bottom resetcapability to perform the 993 poklevki. TVs - the prototype can be made into solid form, and in folding version. When performing fuel assemblies in the folding version of the reliability of its work in the core of a nuclear reactor is reduced by performing chamfer on each cell from the side of the lower end of the lower grille that under conditions of high temperature and high pressure fluid does not exclude the output of the lower plug of a fuel rod out of engagement with the lower grille and a possible “ascent” up.

An object of the invention is to improve the reliability of fastening of the bottom plugs of the fuel Rods in the holes on the bottom of the lattice in the fuel Assembly in the folding and not the folding options and reducing the complexity of manufacture and Assembly.

This technical problem is solved in that in the fuel Assembly of a nuclear reactor, mainly water-cooled nuclear power reactor comprising a bundle of fuel elements installed in the frame of the grid spacers mounted on the tubular channels fastened together with the fuel elements in the bottom grid bottom caps having annular bands, a shank fixed to the lower grille, and a head fixed on the upper ends of the tubular channels; according to the invention the lower grille is made of a composite of at least two repeating on the ug other parts on the location of the holes for the Rods and tubular channels with a total thickness parts, equal to the height of the annular band on the bottom cap of the fuel element and the tubular channel with holes for the bottom stub of the fuel elements and tubular channels, respectively, the diameters of the lower ends of the lower plugs fuel elements and tubular channels, with the fasteners of the lower plugs fuel elements and tubular channels in the holes of the combined parts of the lower grilles made by shifting parts of the lower lattice relative to each other, the lower plugs fuel elements and tubular channels with fixation ring belt on the lower plugs between the annular ledges of the upper and lower parts of the lower grille and a combination of flow-through holes in parts of the lower grille. Another difference is rigid fastening of component parts of the lower grid after their shift to the shank in the non-separable version of the fuel Assembly and collapsible fastener component parts of the lower grid after their shift to the shank in the folding version of the fuel Assembly.

This embodiment, in the fuel Assembly mounts in the composite bottom grid bottom plugs of the fuel Rods and caps tubular channels will provide:

- improve the reliability of their attachment, and at the same time provide as razornet design of the fuel Assembly, nerazborite depending on customer requirements;

to reduce the complexity of manufacturing the component parts of the lower lattice due to their possible stamping when reducing the thickness of the component parts of the lower grille;

to reduce the complexity of Assembly of the fuel Assembly by performing just one operation of the shift component parts of the lower lattice relative to each other and the ring belts of the lower plugs fuel elements after their Assembly in the lower grille.

The drawings show:

figure 1 is a fuel Assembly of a nuclear reactor;

figure 2 - the moment you enter the lower plug of the fuel element in a combined hole parts lower grilles;

figure 3 - position of the lower stopper of fuel elements after shifting parts of the lower grille.

A fuel Assembly of a nuclear reactor, mainly water-cooled nuclear power reactor, includes a bundle of fuel elements 1 mounted in the frame of the grid spacers 2, mounted on the tubular channels 3, secured together with heat-generating elements 1 in the lower grille 4 bottom plug 5 having an annular bands 6, the shaft 7 fixed to the lower grating 4, and the head 8 mounted on the upper ends of the tubular channels 3. The head 8 is fixed with the possibility of its removal.

Lower grille 4 are ostalnoe, at least two repeating each other's parts 9, 10 at the location of the holes 11 for the fuel elements 1 and tubular channels 3 with a total thickness “H” parts 9, 10, equal to the height “H1” ring belt 6 on the lower cover 5 of the fuel element 1 and the tubular channel 3 with a diameter “D” of the holes 11 for the lower stub 5 of the fuel elements 1 and tubular channels 3, respectively, the diameter “D1” of the lower ends 12 of the lower plugs 5 of the fuel elements 1 and tubular channels 3.

The fasteners of the lower plugs 5 of the fuel elements 1 and tubular channels 3 carried out by shifting parts 9, 10 of the lower grille 4 relative to each other and lower stoppers 5 fuel elements 1 and tubular channels with 3 fixation ring belt 6 on the lower plugs 5 between the annular ledges 13, 14 top 9 and bottom 10 parts of the lower grille and a combination of flow-through holes 15, 16 in the composite parts 9, 10 of the lower grating 4. In the non-separable version of the fuel Assembly component parts 9, 10 of the lower grille 4 after their shift is rigidly fixed to the shank 7.

In the folding version of the fuel Assembly component parts 9, 10 of the lower grille 4 after shifting fastened to the shank 7 with the possibility of disassembly.

Fuel Assembly assemble as follows. Previously the sweep frame of the grid spacers 2 on tubular channels 3. The lower plug 5 with the annular belts 6 are placed in the aligned holes 11 of the lower grating 4 in the composite parts 9, 10. Pressed the fuel Rods 1 in the spacer grid 2 and the holes 11 and the ends 12 of the lower plugs 5 in component parts 9, 10 of the lower grating 4. The injection of the fuel Rods 1 in the spacer grid 2 and into the holes 11 of the lower grille 4 are carried out with application of the lubricant applied on the surface of the fuel Rods 1, which is pre-coated with water-soluble varnish. At the end of the Assembly of component parts 9,10 lower grille 4 are located between the annular ledges 13, 14 of the ring band 6 lower plug 5 of the fuel rod 1 and the flow holes 15, 16 are not the same. The fasteners of the lower plugs 5 in the lower grille 4 is offset component parts 9, 10 and their fixation in the annular shoulder 6 of each fuel rod 1 and tube 3 channel between the annular ledges 13, 14 of the lower plugs 5. When moving parts 9, 10 flow-through holes 15, 16 will occupy the axial position. The shank 7 is fixed to the lower grating 4 is rigidly with non-separable variant of FA or with the possibility of disassembly when the folding version of FA. The cylinder 8 is fixed on the upper ends of the tubular channels 3 with the possibility of its removal. When replacement of a fuel rod or Rods is sufficient to perform a reverse shift parts 9, 10 of the lower grille 4 when removing the cylinder 8 and the shank 7.

2. A fuel Assembly of a nuclear reactor according to claim 1, characterized in that the fastening parts of the lower grid after their shift to the shank in the non-separable version of the fuel Assembly carry out harshly.

3. A fuel Assembly of a nuclear reactor according to claim 1, characterized in that the fastening parts of the lower grille in the folding version of the fuel Assembly to the shank carried out with the possibility of disassembly.



 

Same patents:

The invention relates to a mechanical Assembly production, in particular to an Assembly of fuel elements (FE) in the fuel assemblies, primarily for commercial reactors of VVER-10000, VVER-440

The invention relates to a fuel element of a nuclear reactor with spaced with a gap from each other, near and parallel to each other by rods, of which at least one is containing nuclear fuel in a fuel rod, and which are each respectively through the cell having the form of a grid spacer separator, and with the following characteristics:

a) having the form of a lattice, the separator is placed on the edge of the external enclosure of sheet metal, which is orthogonal to the terminals of the reference plane to form the contour of a regular hexagon external racks

b) having the form of a grid separator has an internal cell walls of cells which formed set on edge within this circuit racks sheet metal,

c) the angles of the cells of all internal cells having the form of a lattice separator to form a orthogonal to the terminals of the reference plane angles of regular hexagons internal counters, which all have the same length sides,

d) having the form of a grid separator has an outer cells, which contain at least one formed external rack wall of the cell and the other two smichaud the

FIELD: nuclear power engineering; spacing apart fuel elements in reactor fuel assemblies.

SUBSTANCE: proposed method includes insertion of auxiliary inserts in assembly field holes designed for guide channels and central tube with desired inscribed circumference in each hole prior to spot welding of subchannels to join them together in assembled field; these auxiliary inserts have same diameter as guide channel and central tube and their temperature coefficient of linear expansion equals that of subchannel material; spot welding of subchannels to each other and to rim is effected while inserts are installed and upon heat treatment these inserts are removed.

EFFECT: enhanced quality and yield of spacer grids.

1 cl, 1 dwg

FIELD: nuclear power engineering; spacing apart fuel elements in reactor fuel assemblies.

SUBSTANCE: proposed method includes insertion of auxiliary inserts in assembly field holes designed for guide channels and central tube with desired inscribed circumference in each hole prior to spot welding of subchannels to join them together in assembled field; these auxiliary inserts have same diameter as guide channel and central tube and their temperature coefficient of linear expansion equals that of subchannel material; spot welding of subchannels to each other and to rim is effected while inserts are installed and upon heat treatment these inserts are removed.

EFFECT: enhanced quality and yield of spacer grids.

1 cl, 1 dwg

FIELD: nuclear engineering.

SUBSTANCE: proposed method primarily used for manufacturing spacer grids of VVER reactor fuel assemblies involves pre-compression of dynamometric clamp by welding gun electrodes prior to spot welding of shaped subchannels beyond subchannel field, evaluation of compression of welding gun electrodes by displacement distance of clamp jaws and force indicator readings, whereupon information about this compression force is processed in computer and passed to spatial displacement actuating mechanism of welding gun for conducting spot welding of shaped subchannels in assembled field when compression forces of electrodes comply with desired values or for ceasing spot welding when compression forces do not comply with desired values, this information being displayed on computer monitor.

EFFECT: enhanced quality of spacer grid manufactured by this method.

1 cl, 3 dwg

FIELD: nuclear engineering.

SUBSTANCE: proposed method primarily used for manufacturing spacer grids of VVER reactor fuel assemblies involves pre-compression of dynamometric clamp by welding gun electrodes prior to spot welding of shaped subchannels beyond subchannel field, evaluation of compression of welding gun electrodes by displacement distance of clamp jaws and force indicator readings, whereupon information about this compression force is processed in computer and passed to spatial displacement actuating mechanism of welding gun for conducting spot welding of shaped subchannels in assembled field when compression forces of electrodes comply with desired values or for ceasing spot welding when compression forces do not comply with desired values, this information being displayed on computer monitor.

EFFECT: enhanced quality of spacer grid manufactured by this method.

1 cl, 3 dwg

FIELD: nuclear power engineering.

SUBSTANCE: proposed method is used for manufacturing fuel assemblies for type VVER-1000 and VVER-440 reactors. In order to check spacer grid for passability it is placed in machine between two covers with depressions that follow grid outline and blind holes coaxial to each subchannel of grid accommodating calibrated balls, then it is tuned together with covers through 180 deg., subchannels of inadequate caliber are detected and burnished by means of drift. For checking diameter of circumference inscribed in subchannel the grid is placed in machine equipped with large-diameter calibrating balls, subchannels through which these balls have passed are detected and squeezed by means of clamping tool with jaws disposed in holes between subchannels. Decision on quality of spacer grid subchannels is taken by sticking of balls in them as spacer grid is turned in machine through 180 deg. Balls of different diameters are differently colored.

EFFECT: enhanced quality and yield of spacer grids.

2 cl, 4 dwg

The invention relates to nuclear energy and may find application in enterprises that manufacture fuel assemblies (FA) for nuclear power reactors

The invention relates to nuclear engineering and can be used in the active channel zones of uranium-graphite nuclear reactors, formed from the fuel assemblies, the design of which takes into account the previous and subsequent operation of the active zone

The invention relates to nuclear energy and may find application in the companies that manufacture the spacer grating of stainless steel for fuel assemblies of a nuclear reactor

The invention relates to nuclear energy and may find application in the companies that manufacture the spacer grating of stainless steel for fuel assemblies of a nuclear reactor

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: mechanical engineering.

SUBSTANCE: proposed method is intended for manufacturing fuel elements using resistance-butt welding primarily for their joining to zirconium alloy cans. Welding is effected at equipment electrical resistance not over 30-fold resistance of can section forming welded joint having or not point discontinuities in the form of separate spots or chain of such spots forming no continuous line and measuring maximum ten thicknesses of weld in cross-sectional area of welded joint under check disposed at distance equal to two or three thicknesses of can wall from butt-end of plug located inside fuel element, welded joint being checked by uniformity of external fin. Length of poor fin formation section does not exceed 10% of joint perimeter.

EFFECT: enhanced quality of welds and reliability of fuel element sealing.

2 cl

FIELD: nuclear power engineering; manufacture of fuel elements for fuel assemblies of nuclear power reactors.

SUBSTANCE: proposed process line has mechanism for press-fitting bottom plug in calibrated end of can provided with cutoff gear for piece-by-piece feeding of bottom plugs of different types that incorporates bottom plug passage duct accommodating C-shaped member with reciprocating horizontal-motion actuator whose top flap has slot engageable with upper cylindrical part of bottom plug; bottom flap is longer than top one and is provided with bottom plug passage hole shifted toward edge of bottom flap; flaps are spaced apart through distance slightly longer than maximal length of thick end of bottom plug; rod designed for press-fitting bottom plug in calibrated end of can has bed with seat to receive bottom plug, maximal-size portion of seat following shape of bottom plug.

EFFECT: enlarged functional capabilities of process line for manufacturing fuel-element cans of different sizes.

1 cl 7 dwg

FIELD: power engineering, namely nuclear power reactors, particularly sealing of fuel elements by means of contact butt welding with use of plugs.

SUBSTANCE: apparatus includes sealed welding chamber with housing non-detachable at operation and having through duct for feeding parts to welding zone; mechanisms for sealing welding chamber; device for feeding parts to welding zone; additional clamp of tube; mechanisms for gripping and fixing welded parts; drive device for supplying welding pressure; autonomous drive units. Mechanisms for gripping and fixing welded parts are in the form of collet chucks with respective drives. Welding pressure supply drive device is connected with electrode holder of plug. Welding chamber is restricted by non-detachable housing and flange-current supply lead that is fluid -tightly connected with housing and fixed relative to housing at operation. One collet chuck has annular detachable current supply lead in the form of sectors and it rests by its end at side of large base of petal cone upon said flange-current supply lead. Collet chuck of tube grip and electrode-holder of plug have coaxial electrically insulated one relative to other tie rods arranged in through duct of chamber and joined with autonomous drive units.

EFFECT: enhanced stability of process, improved quality of welded joint due to lowered misalignment of tube and plug.

1 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: atomic power engineering.

SUBSTANCE: device has welding chambers having apertures for inputting covers for pressurization, which concurrently are output apertures of heat-conductive elements, welding chambers electrodes, power source, transporting module for transverse product feed, common control system with blocks for parallel and serial connection, device for forming a break in secondary contour. Welding chambers are placed in parallel to each other at distance from each other, determined from formula S=t(m k+1), where S - distance between chambers axes, t - step of transport module, k - number of chambers in device equal to number of steps of transporting module in each singular step thereof, m - any integer starting from one, and control systems connected through parallel connection block to working tools of device of same names, and through block for serial connection to welding force drive and to device for forming break in secondary contour of power source, as well as to power source connected in parallel to welding chambers electrodes.

EFFECT: higher efficiency.

4 cl, 1 dwg

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