• 专利附录
  • 专利说明
  • 权利要求
  • 类似技术
  • 同族专利
  • 引用文献
  • 法律状态
  • 优先权
    • 专利摘要:

    公开号:SE1150373A1
    申请号:SE1150373
    申请日:2011-04-28
    公开日:2011-06-22
    发明作者:Sten Borell；Tomas Rostvall
    申请人:Westinghouse Electric Sweden；
    IPC主号:
    专利说明:

    10attaching a lower end plug, the lling the interior of the fuel rod with fuelpellets and helium gas, positioning the upper end plug to abut the upperend of the cladding tube: at an interface, and applying a laser beam of alaser source. The proposed laser is a pulsed laser. The laser beam isdirected to a welding zone at the interface to melt material of the endplug and the cladding tube at the interface.
    US-5231261 discloses a pulsed laser welding equipment for welding offuel rods and monitoring the laser beam. The monitoring of the phasesbeam is done before the beam passes through the protective lens. lt cantherefore not identify changes to the protective lens e.g. from sootemanating from the welding process. The welding equipment setup forthe girth welding is not done under pressure. The welding under heliumpressure is done in a separate setup for a hole lling hole, thus noteliminating the need for such a holelling hole and welding process step.
    US-5958267 discloses a method for welding fuel rods under highpressure and to control the laser position with a video system. Themethod claims to prevent soot accumulating on a laser window and tolimit plasma formation. ln practice this is difficult to achieve and theprocess, without control of the plasma, is possibly unstable.
    US-6670574 discloses a laser weld monitoring system for monitoring thewelding of a pulsed laser beam. The system comprises two sensors, onesensor for sensing infrared radiation and one sensor for sensingre ection ection of the light of the faser beam. The method proposes essentiallya trial and error method with a plurality of welds to correlate thecomplicated sensor curves to welding properties.
    US-5651903 also discloses a system for monitoring laser welding bymeans of an equipment comprising two sensors arranged beside theoptical path of the laser beam. First sensor senses infrared radiation ofthe temperature of the weid and a second sensor senses ultravioletradiation of the plasma of the weld. The electrical signals are used tomonitoring Variations compared to a predetermined anomaly valuesobtained by empirical testing.
    US-6710283 d iscloses further laser weld monitoring system. The systemcomprises two sensors arranged beside the optical path of the laserbeam. A first sensor senses re ected light of the l-aser beam and asecond sensor, called a plasmatic sensor, senses the light emitted fromwelding zone. The method uses the frequency spectrum to compareactual variations in the signal with predetermined threshold values.
    SUMMARY OF THE INVENTIONThe object of the present invention is to provide an improved method. ofwelding a fuel rod, especially of welding end plugs without a hole to acladding tube of the fuel rod.
    This object is achieved by the method initially de fi ned, which ischaracterized by the method steps of the characterizing portion of claim1.
    By sensing different waveiengths of the radiation from the welding zoneit is possible to monitor the quality of the weld and the joint of the endplug and the fuel rod. The three different wavelength ranges areindependent of each other and provides different information. A possibledeviation from a normal value of the radiation within any one of the threewavelength ranges may be used as an indication of an improper weldingprocess enabling the operator to adjust the welding equipment. Forinstance, the operator may adjust the power of the laser source within anallowed range.
    The monitoring provides direct feedback during the welding process, andthus a warning if anything goes wrong or if there is a trend to be actupon.
    The w rst wavelength range, which may be sensed by a fi rst sensor,includes the wavelength of the laser beam coming from rejections fromthe welding zone. The intensity of this sensed radiation is an indicationof soot or other changes of the transmission of the protective iensesthrough which the laser beams passes. lt also indicates changes ofincoming laser power and changes of rejection on the work piece.
    The second wavelength range, which may be sensed by a secondsensor, includes infrared radiation from melted material in the weldingzone. The intensity of this radiation is thus an indication of thetemperature and size of the melted material. This also indicates theeffectiveness of the welding, i.e. the penetration of the weld.
    The third wavelength range, which may be sensed by a third sensor,includes radiation from plasma in the welding zone. The intensity of thisradiation is an indication of the amount and the extension of the plasmaformed during the welding. An increased signal from the plasma alsoindicate decreasing effectiveness of the welding, i.e. the penetration ofthe weld.
    Compared to earlier methods of monitoring, this method has acomparatively simple and straight fonNard interpretation and does notneed a lot of trial and error weldings to find a welding characteristic tocompare the curves with. ln principal only one good wetd is needed as abase to compare actual welding curves.
    Laser welding for joining end piugs to fuel rods has a plurality ofadvantages compare to other welding methods, such as electron beamwelding and TlG welding. The investment costs are low, for instancesince it is possible to enclose an end section of the fuel rod to bewelded. A relatively smalt encíosure may thus be used, and thus arelatively small fl over space will be occupied by the welding equipment. ltis possible to use one single laser source for sequential welding of aplurality of fuel rods in several welding equipments. Laser weldingenables achievement of a smooth weld surface which is important whenintroducing the fuel rods in spacers of the fuel assembly. The alloydepletion is low ensuring proper corrosion resistance. There is no risk oftungsten contamination from a TIG seai welding of a fill hole.
    The sensing and monitoring may take place during the whole time periodof the welding of the joint between the end plug and the cladding tube.
    The fuel rod is rotated during the welding so that the laser beam ismoved relatively the fuel rod along the interface. The welding may beperformed during one, two or more revolutions of the fuel rod. Typically,the velocity of the rotation may be about 1 revolution per second, whichmeans that the welding of the end plug to the cladding tube may last forabout 2 seconds.
    According to an embodiment of the invention, said reflections alsoincludes reflections, or partial reflections, of the laser beam in the opticalpath, including protective lenses through which the optical beam passes.
    According to a further embodiment of the invention, the radiation of atat least one of the first wavelength range, the second wavelength rangeand the third wavelength range is sensed along a direction being coaxialwith the optical path at least in the proximity of the welding zone. Theradiation to the different sensors may thus be diverted from the opticalpath to the interface.
    According to a further embodiment of the invention, the method alsocomprises viewing of the welding zone before, and / or during, the weldingand melting of material by means of a video camera. lt is thus possiblefor the operator to inspect the interface before the welding is initiated.
    Advantageously, the method may also comprise controlling the laserbeam position relative the interface by means of the viewed interface.
    Furthermore, the viewing of the welding zone may take place along aviewing direction being coaxial with the optical path at least in theproximity of the welding zone.
    According to a further embodiment of the invention, the method alsocomprises the step of controlling the power of the laser beam inresponse to the sensed radiations.
    According to a further embodiment of the invention, the setup of thelaser equipment is optimized and / or controlled using any anomalies ofthe signal curves from the three different wavetengths. Uneven signalcurves compared to a reference signal curve from earlier approvedwelding test indicate uneven interface or wobble or dirt in the weldingarea and may lead to pores or uneven welding quality.
    According to a further embodiment of the invention, the monitoring stepcomprises monitoring the intensity of the radiation of the first wavelengthrange as first signal level over time to form first signal curve,monitoring the intensity of the radiation of the second wavelength range,as a second signal level over time to form a second signal curve andmonitoring the intensity of the radiation of the third wavelength range asa third signal level over time to form a third signal curve. The setup of thewelding equipment may be optimized and / or controlled using the signalslevels from the three different wavelengths.
    According to a further embodiment of the invention, the methodcomprises the step of optimizing and verifying the setup of the weldingequipment including the power level of the laser beam and the alignmentof optical path, including lenses and / or protective lenses, with the signallevel of the fi rst wavelength range that includes the radiation of there fl ection of the laser beam. During grazing the same signal level maybe used to controi any changes of the transmitted laser beam, e.g. dueto soot on the protective lens just above the weld-ing zone.
    According to a further embodiment of the invention, the methodcomprises the step of controlling the focus position, effectiveness and / orpenetration of the laser beam by the signal level of the secondwavelength range that includes the infrared radiation from the meltedmaterial. An increased infrared signal may correspond to a deeperpenetration of the weld.
    According to a further embodiment of the invention, the methodcomprises the step of controlling the effectiveness and the penetration ofthe welding by the signa! level of the third wavelength range thatincludes the radiation from the plasma. An increased plasma signal maycorrespond to less penetration of the weld.
    According to a further embodiment of the invention, the methodcomprises the step of monitoring any anomalies of any of the signalcurves from the three different waveiength ranges compared to areference signal curve, for instance formed by previously approved weldingtests, to indicate uneven interface or wobble or dirt in the welding zoneand / or possible occurrence of pores or uneven welding quality.
    According to a further embodiment of the invention, the laser beam is acontinuous laser beam. The continuous laser can be generated by e.g. aYb: YAG- fi bre pumped by inGaAs diodes. Typically 500 W laser power isused. The present method is further simpli fi ed when used with acontinuous laser beam which gives simple stable signals compared toembodiments with a pulsed laser.
    According to a further embodiment of the invention, the waveiength ofthe laser beam lies in the range 1050-1090 nm, preferably in the range1060-1080 nm, for instance 1070 nm.
    According to a further embodiment of the invention, the secondwaveiength range is 1100-1800 nm.
    According to a further embodiment of the invention, the third waveiengthis less than 600 nm, preferably 50-600 nm, more preferably 100-600 nm.
    The signal of the plasma is improved compared to other embodimentsthat uses only ultraviolet light below 390 nm. Thus, a preferred range ofthe third waveiength could be 390-600 nm, or 400-600 nm.
    According to a further embodiment of the invention, the welding takesplace in a closed enclosure containing an atmosphere of helium at apressure above the atmospheric pressure. A gas of ow of typically 50 litersper minutes may be advantageous for limiting the plasma and sootformation and thus protecting the lens above the welding zone. The gasfl ow preferably enter the equipment below the protective lenses and fl owcoaxial with the laser beam passing the welding zone. By performing thewelding in such a closed enclosure, the welding may be performed inonly two steps, one step for the bottom plug and one for the top plug,without the need of a hole fi hole to be welded after the welding along theinterface. Elimination of the whole hole will cut costs and risks in differentways. There witl be lower costs for top end plugs with no fill holes. Noseparate tïlt hole weld station is needed. No hole weld inspectionequipment is needed. There is obviously no yield loss for seal welding.
    The risk of tungsten contamination is eliminated.
    The welding may also be performed with other protective gases e.g.argon. When welding the end nal end plug this can only be done after asecured and sealed attachment of the end plug to the cladding tube asthe interior of the fuef rod must contain helium. Welding with argon ischeaper but the welding is less stable and the needed welding power ishigher due to a larger formation of plasma in the argon atmosphere.
    According to a further embodiment of the invention, the closed enclosureencloses the end plug and an end section of the cladding tube, whereinthe method may comprise the preceding steps of: evacuating the interiorof the cladding tube and the closed enclosure to a certain vacuum levelduring a predetermined time period, and then the lling the closed enclosureand the interior of the cladding tube with helium to a predeterminedpressure.
    Furthermore the method may comprise the steps of: prepositioning theend plug on the cladding tube at a determined distance from thecladding tube before the evacuating step, thereby permitting a free fl owof gas from and to the interior of the cladding tube, and fina! positioningof the end pfug on the cladding tube after the fi lling step and before thewelding step. Advantageously, the prepositioning of the end plug at thedetermined distance is made by means of a mechanical stop, which maybe displaceable to be introduced into the distance between the cšaddingtube and the end plug, and withdrawn therefrom.
    LETTER DESCRIPTIONS OF THE DRAWINGSThe invention is now to be explained more closel-y through a descriptionof various embodiments and with reference to the drawings attached-hereto.
    Fig. 1 discloses an iongitudinal section through an end section of afuel rod, where the end plug is positioned at a distancefrom the cladding tube.
    Fig. 2 discloses an iongitudinal section through the end section ofthe fuel rod, where the end plug is abutting the claddingtube.
    Fig. 3 discloses an iongitudinal section through the end section ofthe fuel rod, wherein the end plug and the cladding tube arewelded.
    Fig. 4 discloses a schematic view of a welding equipment.
    Fig. 5 discloses a diagram of the intensity of the radiation of thefirst wavelength range.
    Fig. 6 discloses a diagram of the intensity of the radiation of thesecond wavelength range.
    Fig. 7 discloses a diagram of the intensity of the radiation of thethird wavelength range.
    DETAILED DESCRIPTION OF VARIOUS EMBODIMENTSFigs. 1 - 3 disclose a fuel rod 1 including a cladding tube 2 and two endplugs 3, one of which is disclosed. The fuel rod t. Includes an upper endplug 3 at the upper end of the cladding tube 2, and a lower end plug atthe lower end of the cladding tube 2. The fuel rod 1 also includes a pileof fuel pellets 4 in the interior of the cladding tube 2. The fuel pellets 4rest directly on the lower end plug. A so called plenum spring 5 isprovided between the upper end of the pile of fuel pellets 4 and theupper end ptug 3 to maintašn the fuel pellets in a proper position in theciadding tube 2 and to ensure a plenum 6 for containing helium andEmission gases generated during the nuclear process in the nuclear reactor.
    The nuclear reactor may be a boiling water reactor, BWR, or apressurized water reactor, PWR. The initial pressure prevailing in thefuel rod 1 iled iled with helium is typicaiiy 5-10 bars for a BWR, and 30-70bars for a PWR.in the embodiments disciosed, the ciadding tube comprises an outertube 2 'and an inner tube 2 ”a so called ïiner.
    Fig 4 discloses a welding equipment for welding the end plug 3 to theciadding tube 2. The welding equipment comprises a chuck 10 forholding and rotating the fuel rod and a closed enclosure 11 into which anend section of the fuel rod 1 is introduced via a passage, i.e. an endsection of the ciadding tube 2 and one of the end piugs 3. The chuck 10is con fi gured to rotate the fuel rod at a rotary speed of for instance 1revolution per second.
    The closed enclosure 11 comprises or is formed by a pressure resistantwall 12. A sealing 13 extends through the wall 12 to sea! the passage forthe fuel rod 1.
    First positioning 'device 14 is provided to extend through the wall 12 atan end opposite to the sealing 13. The position rst positioning device 14comprises a movable piston 15 acting on the end plug 3 of the fuel rod 1along the longitudinal direction of the fuel rod 1.
    Furthermore, a second positioning device 16 is provided to extendthrough the wait 12. The second positioning device 16 comprises amechanicai stop 17 provided in the enclosure 11 to be displaceablealong a transversal direction y, being transversal to the iongitudinaidirection x of the fuel rod 1 between a passive position shown in Fig 4and an active position shown in Fig 1. The mechanicai stop 17 when inthe active position maintains the and plug 3 at a determined distancefrom the ciadding tube 2 so that gases may be evacuated from theinterior of the fuel rod and helium may be filled into the fuel rod 1. Whenthe mechanicai stop 17 is withdrawn to the passive position the end plug3 may be brought to the fi nai position and tight abutment to the ciaddingtube 2 by means of the first positioning device 14.11Furthermore, the enclosure 11 comprises a first protective lens 21forming a part of the wall 12 of the enclosure 11. A second protectivelens 22 is provided within the enclosure inside the first protective lens21. The first protective lens 21 is relatively thick and con- gured towithstand the pressure prevailing in the enclosure 11. The secondprotective lens 22 is thinner than the first protective lens 21 andcon fi gured to protect the protective rst protective lens against soot formed duringthe welding.
    A gas supply device 23 is provided for supplying a gas supply, in theembodiments described helium, to the enclosure 11. The gas supplydevice 23 comprises a supply conduit 24 and an annular nozzle providedin the enclosure 11. The annular nozzle 25 is provided between thesecond protective lens 22 and the fuel rod 1, and extends around thesecond protective lens 22. The flow of helium gas to the enclosure maybe for instance about 50 liters per minute. The gas supply device 23 iscon fi gured to provide a gas pressure in the enclosure equal to the gasthat is to be achieved in the fuel rod when both the end plugs aresecured and welded to the cladding tube 2.
    The welding equipment also comprises a laser source 30 con fi gured togenerate a continuous laser beam. The taser source 30 may, forinstance, comprise a Yb: YAG fi bre laser with a wavelength in the range1050-1090 nm, preferably in the range 1060-1080 nm, for instance 1070nm. The YBNAG- fi bre may be pumped by lnGaAs diodes.
    The laser source 30 transmits the laser beam via a fi bre 31 to a primaryoptic 32. The primary optic 32 transmits the laser beam to a primarymirror 33 via a secondary semitransparent mirror 34. From the primarymirror 33 the laser beam is reflected and dšrected to the fuel rod 1 and awelding zone 36 at an interface 37 between the end plug 3 and thecladding tube 2.
    The laser beam thus extends along an optical path from the laser sourceto the welding zone 36. The laser beam, refiected by the primarymirror 33, passes through at least one optical focusing lens 35, the fi rst12protective lens 21 and the second protective lens 22 along the opticalpath.
    The welding equipment also comprises a sensing device including a fi rstsensor 41, a second sensor 42 and a third sensor 43. During weldingradiation from the weld zone 36 is transmitted to the sensors 41, 42 and43 along the optical path through the second protective lens 22, the firstprotective lens 21 and the optical lens 35. The radiation is the reflectedby the primary mirror 33 and the secondary mirror 34 away from theoptical path of the laser beam. The radiation from the welding zone 36 isthus extending along a direction that is coaxial with the optical path inthe proximity of the welding zone 36 at least along a straight line fromthe wetding zone 36 or to the secondary mirror 34. The sensing devicemay be operated at a sampling frequency of up to 20 kHz.
    Via a first semitransparent mirror 44 the radiation is reflected to the fi rstsensor 41. Via second semitransparent mirror 45 the radiation isre ected ected to the second sensor 42. The radiation passes through thesemitransparent mirrors 44, 45 and 46 to the third sensor 43.
    The sensor rst sensor 41 is con fi gured to sense radiation from the weldingzone 36 within a first wavelength range, which includes the wavelengthof the laser beam coming from reactions from the welding zone 36, i.e.wavelengths in the range 1050-1090 nm, preferably in the range 1060-1080 nm, for instance 1070 nm. The reflections from the welding zone36, that are reflected via a second semitransparent mirror 45, alsoincludes reflections, or partial reflections, of the laser beam in the opticalpath, including the fi rst and second protective lenses 21, 22 and the atat least one optical lens 35.
    The second sensor 42 is con fi gured to sense radiation from the weldingzone 36 within a second wavelength range different from the fi rstwavelength range. The radiations are re ected to the second sensor viaa third semitransparent mirror 46. The second wavelength rangeincludes infrared radiation from melted material in the welding zone 36.
    The second wavelength range is 1100-1800 nm.13The third sensor 43 is con fi gured to sense radiation from the weldingzone 36 within a third wavelength range different from the fi rstwavelength range and the second wavelength range. The radiations tothe third sensor passes through the semitransparent mirrors 44, 45 and46. The third wavelength range includes radiation from plasma in thewelding zone 36. The third wavelength is less than 600 nm, preferably50-600 nm, more preferably 100-600 nm.
    The welding equipment also comprises a monitoring device con fi guredto monitor the welding and melting of materia! by monitoring the sensedradiations. The monitoring device comprises a processor 50 and adisplay 51 communicating with the processor 50. The sensors 41-43communicate with the processor 50 which receives signals of theradiation of the three wavelength ranges from the sensors 41-43. Themonitoring device is thus contigured to monitor to an operator on thedisplay the intensities of the wavelength ranges, i.e. the intensity of theradiation of the first wavelength range as first signal level (in volts) overtime (in seconds) to form a first signal curve 56, as illustrated in Fig 5,the intensity of the radiation of the second wavelength range, as asecond signal level (in volts) over time (in seconds) to form a secondsignal curve 57., as illustrated in Fig 6 and the intensity of the radiation ofthe third wavelength range as a third signal level (in volts) over time (inseconds) to form a third signaš curve 58, as illustrated in Fig 7. Thesignal curves 56-58 can be saved by the processor for future use asreference or quality assurance.
    The signal curves 56-57 may be inspected or monitored to lie within anupper timit line L1 and a lower limit line Lz. The upper and lower limitlines Lt, Lz may represent a deviation of 15%, or preferably of 10%, froma desired signal level.
    The signal curves 56-57 may also, or alternatively, be inspected ormonitored in relation to a reference line R representing a desired signallevel. The line R can alternatively be a saved reference curve from one14good weld. The line R can alternatively be a saved reference curve froma mean value curve from several good welds.
    Moreover, the welding equipment comprises a viewing device conflguredto enable viewing of the welding zone before, andlor during, the weldingand melting of material. To that end the viewing device comprises avideo camera 61, a processor 62 and a display 63. lf the viewing deviceis to be used before welding, the enclosure 11 may be illuminated bye.g. LED light. The viewing of the welding zone 36 may take place alonga viewing direction being coaxial with the optical path in the proximity ofthe welding zone 36 at least along a straight line from the welding zone '36 or up to the secondary mírror 34. Thanks to the viewing device, thelaser beam position relative the interface 37 may be controlled manuallyby the operator when inspecting the interface 37 on the display 63 orautomatically. 'The welding equipment may also comprise means for controlling thepower of the laser beam in response to the sensed radiations by meansof the processor 50 controlling the output of the laser source 30. Thecontrolling may be performed manually by the operator when inspectingthe signal curves shown on the display 51 or automatically.
    The controlling may, preferably as an initial measure, comprise the step.of verifying the setup of the welding equipment including the power levelof the laser beam and the optical path with the signal level of the fi rstwavelength range that includes the radiation of the re ection of the laserbeam.
    During welding, or between the welding of the fuel rods 1, the controllingmay comprises the steps of:- controlling the focus position of the laser beam by the signal level of thesecond wavelength range that includes the infrared radiation from themelted material, and / or- controlling the effectiveness and the penetration of the welding by thesignal level of the wavelength that includes the radiation from theplasma.
    During welding it is also possible to monitor any anomalies any of thesignal curves from the three different wavelength ranges compared to areference signal curve to indicate uneven interface or wobble or dirt inthe welding zone and / or possible occurrence of * pores or uneven weldingquality.
    The method and the welding equipment enable achievement of asmooth and uniform weld. The shape of the ished nished weld W is illustratedin Fig 3. As can be seen, the surface of the surrounding weld W is evenwith the surface of the cladding tube 2 and the end plug 3.
    Welding of a fuel rod 1 may comprise the following steps:- prepositioning a bottom end plug to a bottom end section of a claddingtube 2,- introducing the bottom end section into the enclosure 11 and holdingthe fuel rod 1. by means of the chuck 10,- activating the first positioning device 14 to press the bottom end plugagainst the cladding tube 2,- evacuating the enclosure 11 to a certain vacuum level during apredetermined time period,- rotating the fuel rod 1 by means of the chuck 10,- inspecting the position of and positioning the interface 37 with the aid ofthe viewing device,- initiating the welding by the laser source 30,- monitoring the signal curves 56-58 illustrating the intensity of the threewavelength ranges,- removing the fuel rod 1 from the enclosure 11,- prepositioning a top end plug 3 to a top end section of a cladding tube2,- introducing the top end section into the enclosure 11 and holding thefuel rod 1 by means of the chuck 10,- activating the second positioning device 16 to bring the mechanicalstop 17 into contact with the top end section to ensure the determineddistance between the top end plug 3 and the cladding tube 2,16- evacuating the enclosure 11 a certain vacuum level during apredetermined time period,- fi lling the enclosure 11 and the interior of the fuel rod 1 with helium to adesired predetermined pressure,- removing the mechanical stop 17,~ activating the first positioning device 14 to press the top end plug 3against the cladding tube 2,- rotating the fuel rod 1 by means of the chuck 10,- inspecting the position of and positioning the interface 37 with the aid ofthe viewing device,- initiating the welding by the laser source 30,- monitoring the signal curves 56-58 illustrating the intensity of the threewavelength ranges, and- removing the fuel rod 1 from the enclosure 11.
    The present invention is not limited to the embodiments and descriptionsgiven above but may be varied and modi fi ed within the scope of thefollowing claims.
    权利要求:
    Claims (20)
    [1]
    1. Method of welding a nuclear fuel rod including two end plugs (3), a cladding tube (2) and a pile of fuel pellets (4) in the interior of the cladding tube (2), the method comprising the steps of: bringing one of the end plugs (3) and the cladding tube (2) together to abut each other at an interface (37), and welding the end plug (3) and the cladding tube (2) by means of a welding equipment by applying a laser beam of a laser source (30) of the welding equipment, the laser beam having a wavelength and being directed along an optical path of the welding equipment to a welding zone (36) at the interface (37) to mešt material of the end plug (3) and the cladding tube (2) at the interface (37), characterized by the further steps of: sensing the welding by sensing radiation from the welding zone comprising '- sensing radiation within a fi rst wavelength range, which includes the wavelength of the laser beam coming from reflections from the welding zone (36), - sensing radiation within a sec ond wavelength range different from the fi rst wavelength range, which includes infrared radiation from melted material in the welding zone (36), and - sensing radiation within a third wavelength range different from the first wavelength range and the second wavelength range, which includes radiation from plasma in the welding zone (36), and monitoring the welding and melting of material by monitoring the sensed radiations.
    [2]
    A method according to claim 1, wherein said re fl ections also includes re fl ections ot the laser beam in the optic path, including protective lenses (21, 22) through which the optical beam passes.
    [3]
    A method according to any one of claims 1 and 2, wherein the radiation of at least one of the fi rst wavelength range, the second wavelength range and the third wavelength range is sensed along a 10 15 20 25 30 35 18 direction being coaxial with the optical path at least in the proximity of the welding zone (36).
    [4]
    4. A method according to any one of the preceding claims, also comprising viewing the welding zone before and during the welding and melting of material by means of a video camera (61).
    [5]
    A method according to claim 4, also comprising controlling the laser beam position relative to the interface (37) by means of the viewed interface.
    [6]
    A method according to any one of claims 4 and 5, wherein the viewing of the welding zone (36) takes place along a viewing direction being coaxial with the optical path at the east in the proximity of the welding zone (36).
    [7]
    A method according to any one of the preceding claims, also comprising the step of controlling the power of the laser beam in response to the sensed radiations.
    [8]
    A method according to any one of the preceding claims, wherein the monitoring step comprises monitoring the intensity of the radiation of the first wavelength range as a first signal level over time to form a first signal curve (56), monitoring the intensity of the radiation of the second wavelength range, as a second signal level over time to form a second signal curve (57), and monitoring the intensity of the radiation of the third wavetength range as a third signal level over time to form a third signal curve (58).
    [9]
    9. A method according to claim 8 wherein the method comprises the step of verifying the setup of the welding equipment including the power level of the laser beam and the optical path with the signal level of the fi rst wavelength range that includes the radiation of the re ection. of the laser beam. 10 15 20 25 30 35 19
    [10]
    A method according to any one of claims 8 and 9, wherein the method comprises the step of controlling the focus position of the laser beam by the signal level of the second wavelength range that includes the infrared radiation from the melted material.
    [11]
    11. A method according to any one of claims 8 to 10, wherein the method comprises the step of controlling the effectiveness and the penetration of the welding by the signal level of the third wavelength range that includes the radiation from the plasma.
    [12]
    12. A method according to any one of claims 8 to 11, wherein the method comprises the step of monitoring any anomalies any of the signal curves from the three different wavelength ranges compared to a reference signal curve to indicate uneven interface or wobble or dirt in the welding zone and / or possible occurrence of pores or uneven welding quality.
    [13]
    A method according to any one of the preceding claims, wherein the laser beam is a continuous laser beam.
    [14]
    14. A method according to any one of the preceding claims, wherein the wavelength of the laser beam lies in the range 1050-1090 nm, preferably in the range 1060-1080 nm, for instance 1070 nm.
    [15]
    15. A method according to claim any one of the preceding claims, wherein the second wavelength range is 1100-1800 nm.
    [16]
    16. A method according to claim any one of the preceding claims, wherein the third wavelength is less than 600 nm.
    [17]
    A method according to claim 16, wherein the third wavelength range is 390-600 nm.
    [18]
    18. A method 'according to any one of the preceding claims, wherein the welding takes place in a closed enclosure (11) containing an atmosphere of helium at a pressure above the atmospheric pressure. 10 15 20
    [19]
    19. A method according to claim 18, whereín the closed enclosure (11) encioses the end plug (3) and an end section of the cladding tube (2), and whereín the method comprises the preceding steps of: - evacuating the interior of the cladding tube and the closed enclosure to a certain vacuum level during a predetermined time period, and - then fi lling the closed enclosure and the interior of the cladding tube with helium to a predetermined pressure.
    [20]
    20. A method according to claim 19, whereín the method comprises the steps of: - prepositioning the end plug (3) on the cladding tube (2) at a determined distance from the cladding tube (2) before the evacuating step, thereby permitting a free fl ow of gas from and to the interior of the cladding tube (2), and - fi nal positioning of the end plug (3) on the cladding tube (2) after the fi lling step and before the welding step.
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    同族专利:
    公开号 | 公开日
    US20140251960A1|2014-09-11|
    EP2701876A1|2014-03-05|
    KR20140018958A|2014-02-13|
    WO2012146444A1|2012-11-01|
    US9586287B2|2017-03-07|
    JP2014529056A|2014-10-30|
    SE535767C2|2012-12-11|
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    法律状态:
    优先权:
    申请号 | 申请日 | 专利标题
    SE1150373A|SE535767C2|2011-04-28|2011-04-28|Procedure for welding nuclear fuel rod|SE1150373A| SE535767C2|2011-04-28|2011-04-28|Procedure for welding nuclear fuel rod|
    US14/110,941| US9586287B2|2011-04-28|2012-03-22|Method of laser welding a nuclear fuel rod|
    PCT/EP2012/055076| WO2012146444A1|2011-04-28|2012-03-22|Method of laser welding a nuclear fuel rod|
    KR1020137028329A| KR20140018958A|2011-04-28|2012-03-22|Method of laser welding a nuclear fuel rod|
    EP12709652.7A| EP2701876A1|2011-04-28|2012-03-22|Method of laser welding a nuclear fuel rod|
    JP2014506807A| JP2014529056A|2011-04-28|2012-03-22|Laser welding method for nuclear fuel rods|
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