Aggregate for contact butt welding

FIELD: nuclear power engineering, possibly automatic line for producing fuel elements of fuel assemblies of power nuclear reactors.

SUBSTANCE: aggregate is provided with detachable device for measuring electric resistance of fitting. Said device is arranged between collet chucks being in open position and it is made of two dielectric members spring-loaded one relative to other. End of one of said members has shape corresponding to contour of annular turning formed coaxially on end of collet chuck for plug. End of second member has shape corresponding to contour of annular turning formed coaxially on end of fitting in collet chuck for fuel element envelope. Said device has spring-loaded contacts for measuring electric resistance between fitting inside collet chuck and collet chuck itself. Caprolactam is used as dielectric material.

EFFECT: enhanced efficiency and quality of contact butt welding at sealing fuel element.

2 cl, 3 dwg

 

The invention relates to nuclear energy and may find application in automatic lines for manufacturing fuel elements (FE).

Currently, a large part of fuel Rods for nuclear power plants is sealed at one end electron-beam welding the caps to the shell, and the other end after equipment in the shell preformed nuclear fuel pressure butt welding stub to the shell under the pressure of the inert gas under the shell. Known unit of flash butt welding, called KCC-2, developed in Russia. The formation of the welded connection at KCC-2 is made in conditions of all-round compression zone of the welding ring mandrel, and for welding use a stub of reduced diameter compared to the outer diameter of the sealing membrane (see “Development, production and operation of fuel cell power reactors”. Book 2. Edited Fgurative-M.: Energoatomizdat, 1995 - s-222, RIS).

The mold-refrigerator-electrical power supply in the known Assembly is a ring mandrel. When the clamp Fuel in the annular mandrel thickness of the shell of a fuel rod can be considered as the total thickness of the shell of a fuel rod and a ring mandrel. However, due to the increase of the current shunting through the Chuck (ring die) heating the shell of a fuel rod smart, who would close, the heating zone has a higher recrystallization temperature goes on the outer surface of the connection sheath with cap, capturing the junction of the shell at the end of the stub, which is unacceptable from the viewpoint of the corrosion resistance of the welded connection. The welded joint obtained in solid collet clamp (ring die), is limited to not more than 1,5S (where S is the thickness of the shell). Margin of safety of such compounds and corrosion resistance are low due to the fact that the electrical resistance of the collet clamp ring mandrel) lower than the resistance of the shell.

As a result, the area of the shell is not fully warmed, which limits the depth of crimp plugs on the length of the connection is 1,5S (where S is the thickness of the shell).

Known unit of flash butt welding, containing collet closers with channels for the fuel cladding and plugs installed with the possibility of Autonomous reciprocating motion by means of the actuators with the formation of the welding chamber, communicated with the means of discharging, flow of neutral gas and welding power source.

(See Patent RU 2152091, IPC 7 G 21 21/02 from 07.10.1998, publ. 27.06.2000. “Installation for sealing tubular elements”).

The disadvantage of this unit flash butt welding are similar to the disadvantages of the unit flash butt welding and, above.

The closest in technical essence and the achieved effect is a unit of flash butt welding to the channel to curb nuclear fuel shell and collet with snap-in in the form of a set of isolated from each other plates with resistance 700-1200 µohm collet for plugs that are installed with the possibility of reciprocating motion by means of the actuators with the formation of the welding chamber, communicated with the means of discharging, flow of neutral gas and welding power source. (see Patent RU 2127457, IPC 6 G 21 3/10, 21/00, 21/02 from 04.06.1997, publ. 10.03.1999, Fig, Fig).

The mold-refrigerator-electrical power supply in the patent prototype is snap-fastened inside the collet clamp (see ibid., section 21).

In the patent-prototype tooling in the form of a set of plates (strips), located in the collet clamp to curb nuclear fuel shell may fail.

While damage to the plates gaskets leads to the formation of parasitic circuits through which the bypass welding current.

The current density in the contact of the welded parts is reduced, although the total amount remains unchanged, which leads to underheating of the welded area and deteriorate the weld quality and properties of welded joints.

Long is the work of the collet clamp in conditions of cyclic thermo-mechanical loads may lead to a change in the electrical resistance of the snap in the direction of its increase (see ibid, section 17) due to oxidation of the plates snap-in, which is undesirable, as the welding quality decreases.

In this regard, in the description of the patent-prototype recommended to control the electrical resistance and the absence of shunt circuits before welding (see patent-prototype, section 17), but how to do it, is not specified.

Snap-in the form of isolated plates secured within the collet clamp in the form of a three collets and has an electric resistance 700-1200 µohm that exceeds the resistance area of the membrane that is involved in the formation of the welded connection.

Snap-on number three collets divided into three sectors, which are respectively attached to the petals collets (see ibid., section 21).

In order to measure the electrical resistance of the three sectors of the snap-in you want to disassemble the equipment and remove it from the collet clamp or remove from the Chuck Assembly with snap-in. Both are undesirable, as it violates the established tolerance, it is very difficult to restore them, which is reflected in the quality of welding. In addition, all of these operations require work, reducing performance.

An object of the invention is to improve the quality and performance of flash butt welding to seal teplovi the determinant element.

This technical problem is solved by the fact that the unit flash butt welding to the channel to curb nuclear fuel shell with a collet Chuck with snap-in in the form of a set of isolated from each other plates with electric resistance 700-1200 µohm collet for plugs that are installed with the possibility of reciprocating motion by means of the actuators with the formation closed up welding chamber provided with means of vacuum supply neutral gas and welding power source.

According to the invention the Assembly of flash butt welding is supplied is placed between the collet jaws in separated position removable device measuring the electrical resistance of the snap is made of two spring between the parts of a dielectric material, of which one end part is placed and repeats the shape of the annular groove is made coaxially on the end of a collet clamp to the bracket, and another end of the second part posted and repeats the shape of the annular groove is made coaxially on the end of the snap-in collet clamp for the fuel cladding, and the unit of measurement of electric resistance are equipped with spring-loaded contacts measuring the electrical resistance between the snap inside the collet clamp and C is directly a collet Chuck.

Another difference is used as a dielectric material caprolactam.

Supply unit flash butt welding removable device measuring the electrical resistance of the snap-in will allow you to control the absence of shunt circuits before welding, to identify defective insulating plate strip by sector collet clamp without disassembly and timely manner to carry out their removal and replacement if any damage to the equipment and thereby to achieve the technical solution to improve the quality and performance of flash butt welding to seal the fuel element.

The drawings show a unit of flash butt welding, in which figure 1 is a removable device measuring the electrical resistance of the snap-in Assembly of flash butt welding; 2 removable measuring electrical resistance; figure 3 is a detachable device measurement (top view).

The unit flash butt welding with channel 1 to curb nuclear fuel 2 shell 3 with a collet Chuck with 4 snap 5 inside in the form of a set of isolated from each other plates with resistance 700-1200 µohm collet 6 plugs (not shown)installed with the possibility of reciprocating motion (shown by arrow) through the m actuators (not shown) forming a closed up of the welding chamber, communicated with the means of discharging, flow of neutral gas (not shown) and a source 7 of the welding current.

The unit flash butt welding is supplied inside the collet clamps 4, 6 removable device measuring the electrical resistance of the snap-5, made of two spring between the parts of a dielectric material, of which the one end part 8 repeats the shape of the annular groove 9, is made coaxially on the end of a collet clamp 6 to the bracket, and another end of the second part 10 repeats the shape of the annular groove 11, is made at the end of the snap-5 collet clamp 4 to the shell 3 of the fuel element. The device measuring the electrical resistance provided with spring-loaded contacts 12 measuring the electrical resistance between the snap 5 inside the collet clamp 4 and directly collet 4. As a dielectric material for measurement of electric resistance is used caprolactam.

Measurement of electric resistance is as follows.

Before measuring the electrical resistance of the unit flash butt welding zimovye clamps 4, 6 bred coaxially to the side between them in the groove 9 of the collet clamp 6 install one piece of 8 devices measuring electrical resistance, and in protoco snap-in 5 establish other retaining part 10. This spring-loaded terminals 12 are directly related to the collet clamp 4 and snap 5 inside the collet clamp 4. Turning around its axis parts 10, 8 in the grooves 11, 9 carry out measurement of electric resistance of all three sectors of the snap-5, attached to the petals of a three-collet clamp 4, and the measurement results are transmitted to the measuring device 13.

The measurement results shall decide on the continuation of the flash butt welding by electrical resistance 700-1200 µohm, and when the deviation in direction more or less replace the Chuck with 4 snap 5 inside. Due to the fact that the device measuring the electrical resistance of the parts 8, 10 are biased between the removal device of the collet clamps and install them in device not present difficulties.

1. The unit flash butt welding to the channel to curb nuclear fuel shell with a collet Chuck with snap-in in the form of a set of isolated from each other plates with electric resistance 700-1200 µohm collet for plugs that are installed with the possibility of reciprocating motion by means of the actuators with the formation closed up welding chamber provided with means of vacuum supply neutral gas and welding power source that is different is the present, the unit flash butt welding is supplied is placed between the collet jaws in separated position removable device measuring the electrical resistance of the snap is made of two spring between the parts of a dielectric material, of which one end part is placed and repeats the shape of the annular groove is made coaxially on the end of a collet clamp to the bracket, and another end of the second part posted and repeats the shape of the annular groove is made at the end of the snap-in collet clamp for the fuel cladding, and the unit of measurement of electric resistance are equipped with spring-loaded contacts measuring the electrical resistance between the snap inside the collet clamp and directly collet.

2. The Assembly according to claim 1, characterized in that the dielectric material used caprolactam.



 

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

SUBSTANCE: proposed process line has mechanism for weighing can charged with fuel pellets installed past retainer press-fitting mechanism; can is coupled through computer with mentioned weighing mechanism for outputting data on pure mass of pellets in can; γ-quanta detecting units and pellet enrichment automatic control installations are mounted on charged can guiding facility in the form of rolling train between its rollers throughout length of charged pellet stack; detecting units are disposed around pellet stack charged in can with collimation channels shifted throughout length of charged pellet stack; detecting units are provided with photoelectronic multipliers, spectrometers, and data acquisition, processing and outputting computer. Each detecting unit is provided with through hole passing can-displacement tungsten tube; shifted collimation channels are provided in top and bottom parts of tungsten tube; photoelectronic multipliers are disposed on butt-ends of detecting unit.

EFFECT: enhanced quality of fuel element manufacture.

3 cl, 3 dwg

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

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.

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EFFECT: enhanced quality of fuel elements and their operating reliability in reactor core.

1 cl, 1 dwg

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EFFECT: higher efficiency.

4 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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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

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