SE199888C1

SE199888C1 -

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Publication number: SE199888C1
Authority: SE
Publication date: 1965-01-01

Description

Uppfinnare: S Takahashi, Y Honda, K Ishikawa, H Uchikoshi och T Kubota Prioritet begard Iran den 15 oktober 1959 och den 19 september 1960 (Japan) Foreliggande uppfinning avser ett satt att framstalla ihaliga, keramiska eller "cermet"- karnbran:sleeleinent med hog densitet fOr anvandning i karnreaktorer. Inventors: S Takahashi, Y Honda, K Ishikawa, H Uchikoshi and T Kubota Priority requested Iran October 15, 1959 and September 19, 1960 (Japan) The present invention relates to a method of producing hollow, ceramic or "cermet" high density for use in nuclear reactors.

I prakliken framstalles vanligtvis fasta, keramiska karnbransleelement for karnreaktorer enligt det konventionella pulvermetallurgiska forfarandet, som amfattar komprimering eller pressning och sintring av massor av finkrossade eller pulvriserade keramiska branslematerial, sasom urandioxid-(UO2)-pulver. Det ar ocksa kant, aft framstalla fasta, keramiska karnbransleelernent av hog densitet genom roterande sanksmiding. Roterande sanksmidning är en for fackmannen valkand operation, och finnes i detalj beskriven, I. ex. pasid 243-238 i "Procedures in Experimental Metallurgi" by A. U. Seybolt and J. E. Burke, copyright 1953 by John Wiley and Sons, Inc., New York. The practice usually produces solid ceramic nuclear fuel elements for nuclear reactors according to the conventional powder metallurgical process, which involves compaction or pressing and sintering of masses of finely crushed or powdered ceramic fuel materials, such as uranium dioxide (UO2) powder. It is also possible to produce solid, high-density ceramic nuclear fuel elements by rotating forging. Rotary forging is an operation for the person skilled in the art, and is described in detail, I. ex. pp. 243-238 in "Procedures in Experimental Metallurgy" by A. U. Seybolt and J. E. Burke, copyright 1953 by John Wiley and Sons, Inc., New York.

Om ett enligt nagot .av dessa konventionella forfaranden framstallt keramiskt karnbransleelement anvandes i en karnreaktor, kommer den del av elernentet som befinner sig i narheten av dess langdaxel att ha den raindre neutrontatheten. Till foljd harav liar den del av elementet som är helagen pa eller i omedelbar narhet av langdaxeln en relativt liten verkan. A andra sidan har vane bransleelentent som anvandes i en karnreaktor en sadan temperaturfordelning, att temperaturen i elementet .suceessivt ,minskas frart de centralare delarna i riktning mot de perifera delarna ailed den maximala temperaturen upptradande vid den centrala langdaxeln. Sasom en foljd harav kommer den del av .elementet, som Or belagen i narheten av centrum lattare att smalta an den atersta'ende delen. Vidare ãr, till av den ovan beskrivna temperaturfordelningen, kristallkornens tillvaxt storre i brans leelementets centrala del i jamforelse med tillvaxten i den utanforliggande delen. Detta leder till uppkomsten av koncentriska, cylindriska tamrum inuti elementet, vilket medfor en minskning av clettas radiella varmeledningsformaga. Delta resulterar i en Mining av maximitemperaturen i elementets centrala del, vilkert som en foljd harav, lattare hammer att smalta. If a ceramic nuclear fuel element produced according to any of these conventional methods is used in a nuclear reactor, the part of the element which is close to its long axis will have the purer neutron density. As a result, the part of the element which is sacred on or in the immediate vicinity of the longitudinal axis has a relatively small effect. On the other hand, conventional fuel elements used in a nuclear reactor have such a temperature distribution that the temperature in the element successively decreases from the central parts towards the peripheral parts ailed the maximum temperature occurring at the central longitudinal axis. As a result, the part of the element which is located near the center will more easily narrow than the remaining part. Furthermore, due to the temperature distribution described above, the growth of the crystal grains is greater in the central part of the industry element in comparison with the growth in the outer part. This leads to the formation of concentric, cylindrical domestic spaces inside the element, which leads to a reduction of the radial thermal conductivity of the cleats. Delta results in a Mining of the maximum temperature in the central part of the element, which as a result has, easier hammer to melt.

Dessa nackdelar kunna undvikas genom att branslematerialet borttages fran bransleelementens centrala del eller genom att ihaliga, keramiska bransleelement astadkommas. I enligthet harmed anvandes foretradesvis ett ihaligt, keramiskt karnbransleelement med en. langsghende oppning, sam straeker sig centralt genom elementet, i stallet for ett fast bransleelement. Med andra ord ett sadant ihaligt bransleelement fir fordelaktigt dfirigenom, att dess centrala del jute kan antaga den overdrivet hojda maximitemperaturen, och harigenom fdrhindras att smalta eller termiskt nedbrytas. These disadvantages can be avoided by removing the fuel material from the central part of the fuel elements or by providing durable, ceramic fuel elements. In accordance with this, a hollow ceramic core fuel element with one is preferably used. longitudinal opening, extending centrally through the element, instead of a fixed fuel element. In other words, such a durable fuel element is advantageous in that its central part of the jute can assume the excessively high maximum temperature, and thereby is prevented from melting or thermally decomposing.

Ett kant forfarande att framstalla ett ihaligt karnbransleelement bestar i framstallning av plansintrade kulor Tried ringformigt utse, ende °eh med rektangular genomskarning, enligt det inom pulvermetallurgin konventionella forfarandet, och stapla upp ett antal av de pa sa salt framstallda kulorna i och for bildning av ett ihaligt cylindriskt organ. A. andra sidan erfordras det, att ett bransleelemeat av det ihaliga slaget bar en hog densitet, stor dimensionsnoggrannhet, en bra ratlinjighet, etc. De konventionella pulvermetallurgiska forfarandena innefatta emellertid inte blott ett flertal behandlingssteg for astadkommande av ihâliga karnbransleelement, som uppfyllda dessa fordringar, utan erfordra dessutom oundvikligen bade en mycket hog 2— — sintringstemperatur och en lang sintringstid, vilket leder till hoga framstallningskostnader och dyra produkter. An edge process for producing a hollow core fuel element consists in the production of planar sintered spheres. Tried annular appearance, only with a rectangular cut, according to the conventional method in powder metallurgy, and stacking a number of the spheres produced on such salt in order to form a ihaligt cylindrical organ. A. On the other hand, it is required that a fuel element of the hollow type have a high density, high dimensional accuracy, good linearity, etc. However, the conventional powder metallurgical methods do not only include a plurality of treatment steps for producing hollow core fuel elements which meet these requirements. but also inevitably require both a very high sintering temperature and a long sintering time, leading to high manufacturing costs and expensive products.

Ett andamal med uppfinningen är darfor att astadkomma ett Nitre satt att enkelt och till liten kostnad ,framstallakeramiska karnbransleelement av hog densitet for karnreaktorer, vid vilket de ovannamnda nackdelarna elimineras. An object of the invention is therefore to provide a Nitre set which easily and at low cost produces high density ceramic nuclear fuel elements for nuclear reactors, in which the above-mentioned disadvantages are eliminated.

Ett .annat andamal med uppfinningen är aft astadkomma ett battre satt att framstalla ett ihaligt keramiskt karnbransleelement med hog densitet, vilket kannetecknas av en kropp av ett keramiskt karnbranslematerial, inskjuten mellan ett par koncentriska, cylindriska platror av ett hogsmaltande metalliskt material eller metalliska material, men en i huvudsak pa forhand faststalld yttre och inre diameter och med god ratlinjighet: - Enligt uppfinningen astadhommes ett satt att fraanstalla ett ihaligt keramiskt eller cermet karnbransleelement av hog densitet for karnreaktorer, vilket forfarande i huvudsak kannetecknas av att man fyller ut ett ringformigt utrymine Tnellan ett yttre cylindriskt platror och eft i fOrhallande till delta koncentriskt anordnat inre cylindriskt platror med en mangd av ett keramiskt eller cermet Urnbranslematerial och darefter tillsluter det ringformiga utrymmet, fyller det inre platroret med en kdrna, som liar en elasticitetsmodul av minst 5X3 kg/mTn2 och en flytgrans air minst 5 kg/mTn2, varvid materialet i namnda karna antingen har en smaltpunkt SOM ãr lagre an smaltpunkterna fOr vart och ett av de inre oCh yttre rorens material eller ocksa är mem lattlosligt i en minerals3Ta, utsatter den pa sa satt bildade enheten for roterande sanksmidning, f8r att fortata och sintra det ifyilda branslematerialet till hog densitet ,och darefter avlagsnar karnan frau den sanksmidd.a produkten antingen genom smaltning av densamma eller genom upplosning av densamma i mineralsyran. Another object of the invention is to provide a better method of making a high density ceramic core fuel element which is characterized by a body of a ceramic core fuel material sandwiched between a pair of concentric cylindrical plates of a high melting metallic material or metallic materials, but a substantially predetermined outer and inner diameter and with good linearity: - According to the invention, a method is provided to provide a high density ceramic or cermet nuclear fuel element for nuclear reactors, which process is mainly characterized by filling an annular space. outer cylindrical plate and in relation to the delta concentrically arranged inner cylindrical plate with a quantity of a ceramic or cermet Urnbransle material and then closes the annular space, fills the inner plate with a core, which has a modulus of elasticity of at least 5X3 kg / mTn2 and a flytgr at least 5 kg / mTn2, the material in said vessels either having a melting point THAT is lower than the melting points of each of the inner and outer tubes materials or is also easily soluble in a mineral3Ta, exposing the unit thus formed to rotary forging, to thicken and sinter the filled fuel material to a high density, and then the core is removed from the forged product either by melting it or by dissolving it in the mineral acid.

Karnan har foretradesvis tillraeklig mekanisk hallfasthet for att motsta den hoga spanningspakanningen till foljd av den roterande sanksmidningen och for att kunna uppbara insidan av den inre platen utan att denna deforaneras under ifragavarande operation. The core preferably has sufficient mechanical half-strength to withstand the high stress packing due to the rotating forging and to be able to support the inside of the inner plate without it being deformed during the operation in question.

For att underlatta avlagsnandet av karnan Iran den rotationssanksmidda produkten dr det att fOredraga att det form materialet har en smaltpunkt som dr lagre an smaltpunkten for ,saval det yttre som det inre platmaterialet. Alternativt kan karnan vara ,gjord av nagot 15mpligt material, mera lattlosligt i en mineralsyra. In order to facilitate the removal of the rotan forged product, it is preferable that the mold material has a melting point which is lower than the melting point, both the outer and the inner plate material. Alternatively, the karnan may be made of a slightly soluble material, more easily soluble in a mineral acid.

I avsikt att forhindra att karbider utfallas patarna under den roterande sanksmidningen kunna platarna vara gjorda av nagot lampligt material, sasoan rostfritt stal, innehallande kol i mangd av hogst 0,02 viktprocent. In order to prevent carbides from precipitating during the rotating forging, the plates can be made of a slightly suitable material, such as stainless steel, containing carbon in the amount of at most 0.02% by weight.

Lampligen kan, Indian en yttre plat och en koncentrisk inre plat, fastforankrad I ena Auden till den form med tillhjalp av en plugg, vid den forra platens motsatta finde en ringformig tunn stomme med ett flertal relativt .stora oppningar inforas tattslutande, fOr att pa 'sa salt hjalpa till aft bibehalla de hada platroren koncentriskt I forhallande till varandra, oCh en mangd av ett krossat eller pulvriserat keramiskt branslematerial kan hallas i det ringformiga utrymmet mellan de Mcla platarna genom oppningarna i stommen. Lamply, Indian an outer plate and a concentric inner plate, anchored in one Auden to the shape by means of a plug, at the opposite of the previous plate may find an annular thin body with a plurality of relatively large openings tightly inserted, to pa ' so salt help to maintain the hot plates concentrically in relation to each other, and a quantity of a crushed or powdered ceramic fuel material can be kept in the annular space between the Mcla plates through the openings in the frame.

I avsikt att ytterligare forbattra dimensionsnoggrannheten och den ratlinjighet som shall ges den med ett par koncentriska platror kladda slutprodukten, later man foretradesvis den yttre platen fritt forlangas i forhallande till en karna, soan är fast anordnad inuti den inre platen under den roterande sdnksmidningen. Lampligen kan en med en central oppning forsedd plugg forsluta en .anordning omfattande ,det yttre platroret, det inre platrtiret, ett samananpressat keramiskt ka.rnbranslematerial mellan de hada platroren och kgrnan inuti det inre plaftoret vid detta:s ena dude, vilken slutligen utsattes for roterande sanksmidning med motsvarande ande air karnan uppburen i den namnda centrala oppningen for glidrorelse och med ett lampligt tomrum lamnat mellan karnans dude och hotten i den centrala oppningen I pluggen. In order to further improve the dimensional accuracy and the steering alignment to be given to the end product coated with a pair of concentric plates, the outer plate is preferably left free in relation to a core, the son being fixedly arranged inside the inner plate during the rotary sink forging. A plug provided with a central opening may suitably close a device comprising, the outer plate, the inner plate, a compressed ceramic fuel material between the had plates and the core inside the inner plate at this dude, which is finally exposed to rotary sink forging with the corresponding spirit air karnan supported in the said central opening for sliding movement and with a light void left between the duct of the karnan and the hood in the central opening in the plug.

For fullstandig ffirstaelse ,av arten av och andamalen Tried uppfinningen belysas donna nedan i detalj under hanvisning till bifogade ritning dar fig. 1 i schematisk form visar en langdsektion av en anordning med ett yttre cylindriskt platror ,och ett inre cylindriskt platror, anordnat koncentriskt i forhallande till ,det fOrstnamnda for anvandning mid tilFawning av uppfinningen. For a complete understanding of the nature and nature of the invention, the invention is illustrated in detail below with reference to the accompanying drawing, in which Fig. 1 shows in schematic form a longitudinal section of a device with an outer cylindrical plate, and an inner cylindrical plate arranged concentrically in relation till, the former for use in the practice of the invention.

Fig. 2 visar en vy framifran av en stomme for uppratthallande av eft pa forhand faststallt avstand mellan det yttre och inre platrOret. Fig. 2 shows a front view of a frame for maintaining a predetermined distance between the outer and inner plates.

Fig. 3 visar i schematisk form en Ifingdsektion ay en .anordning med det yttre och inre platroret och en massa av ett keramiskt karnbrdnslematerial, sammanpressat i eft ringformigt utrymine mellan nd.mnda platror, fardig for roterande sanksmidning. Fig. 3 shows in schematic form a filling section of a device with the outer and inner plate and a mass of a ceramic fuel material, compressed in an annular space between the said plates, ready for rotary forging.

Fig. 4 visar schematiskt en langdsektion av den fardiga produkten eniigt uppfinningen. Fig. 4 schematically shows a longitudinal section of the finished product according to the invention.

Under hanvisning till fig. 1 visas ett yttre, cylindriskt patrol. 1 av en andamalsenlig me-tall, anordnat koncentriskt i farhallande till ett hue, cylindriskt platror 2 med ett Indian dessa hada platror utbildat ringformigt ut- rymme 3. Den vanstra anden av det ringforaniga utrymmet 3 sadant det framgar ay fig. 1 är tillsluten med en plugg 4, som är fast ,ansluten till de hada platroren i donna dude t. ex. genom svetsning. Pluggen 4 utgores ,fOretradesvis av rostfritt .stal. Referring to Fig. 1, an outer cylindrical patrol is shown. 1 of a breathable metal, arranged concentrically in relation to a hue, cylindrical plate 2 with an Indian these had plates formed annular space 3. The left spirit of the annular space 3 as shown in Fig. 1 is closed with a plug 4, which is fixed, connected to the hada plates in the donna dude e.g. by welding. The plug 4 is made, preferably of stainless steel.

De hada roren 1 resp. 2 tjana i samverkan — —3 sasom rdr for bekladnad av ett finkrossat eller pulvriserat karnbranslematerial, sá att de aro i stand aft motsta den hoga spanningspakanning, som kan uppstâ under den roterande !sanksmidningen och darjamte besitta god bearhetharhet. Exempel pa Adana plat- material ar rostfria stAl, zirkoniumlegeringar, aluminium, aluminiumlegeringar, niagnesi- iimniob, nioblegeringar och liknan- de. De quest rtillfredsstallande resultaten erhallas med AISI typ 304 L rostfritt stal med foljande sammansattning (i viktprocent). The hada pipes 1 resp. 2 serve in cooperation - —3 as a means of coating a finely crushed or powdered core fuel material, so that they are able to withstand the high stress packing which may arise during the rotating forging and thereby possess good bearing hardness. Examples of Adana plate materials are stainless steels, zirconium alloys, aluminum, aluminum alloys, niagnesium-iimniob, nine-alloys and the like. The quest for satisfactory results is obtained with AISI type 304 L stainless steel with the following composition (in weight percent).

CMnSiPSCrNi <.03 <2.00 <1.00 <.045 <.03 18,0-20,0 8,0-12,0 Det har visat sig, att anvandning av rostfria stal, innehallande kol i mangder av hogst 0,02 %, i hog grad kan forhindra att karbider utfallas i platmaterialet under roterande sanksmidning. Om karbider utfallas i platen under denna operation, kommer spanningen att koncentreras till den del av platen dar karhiderna ha utfallts. Pa grund Wray maste utfallningen av karbider undvikas. CMnSiPSCrNi <.03 <2.00 <1.00 <.045 <.03 18.0-20.0 8.0-12.0 It has been found that the use of stainless steels containing carbon in quantities of logging 0.02%, can to a large extent prevent carbides from precipitating in the plate material during rotating forging. If carbides precipitate in the plate during this operation, the stress will be concentrated to the part of the plate where the carbides have precipitated. Due to Wray, the precipitation of carbides must be avoided.

Det irises, att defekter sadana som rander, sprickor och liknande, saval pa den inre vaggytan av den yttre platen som pa de inre och yttre vaggytorna av den inre platen 2, preliminart skola avlagsnas genom mekanisk bearbetning och kemisk eller elektrolytisk pole-ring. It is irises that defects such as stripes, cracks and the like, both on the inner rock surface of the outer plate and on the inner and outer rock surfaces of the inner plate 2, should be preliminarily removed by mechanical processing and chemical or electrolytic polishing.

For att hjalpa till att bibehalla den hire platen 2 koneentriskt i forhallande till den yttre platen 1, ar en stomme 5 inskjuten i det ringformiga utrymmet 3 i ett pa fOrhand fast-stain lage, som är beroende av mangden av det keramiska karnbranslermaterialet som utfyller det ringformiga utrymmet 3. Stommen 5, som foretradesvis kan tillverkas air en bit rostfritt still, och soin omfattar en inre ringliknande del 5a, avsedd att ligga an mat den yttre vaggytan ph den inre platen 2, en yttre ringliknande del 5b, avsedd att ligga an. mot den hire vaggytan pa den yttre platen 1, ett flertal radiella armdelar Sc, vilka forbinda den inre oeh den yttre ringliknande delen med varandra och ett flertal sektoriella oppningar 5d med resp. delar forbundna med varandra genom svetsning (se fig. 2). Den anvanda Ira-dens diameter .kan variera mellan 0,3 och 0,5 mm. Alternativ-t kan stommen 5 gams air en metallplat, fOretradesvis-av rostfritt stal, med en tjocklek av ca 9,5 mm, genom pragling eller stansning av densamma i onskad form. I detta fall kan stommens resp. delar em sa. Onskas, forbindas med varandra genoxn svetsning. To help maintain the hire plate 2 coenetrically in relation to the outer plate 1, a body 5 is inserted into the annular space 3 in a pre-fixed layer, which depends on the amount of the ceramic core fuel material filling it. annular space 3. The body 5, which can preferably be made of a piece of stainless steel, and soin comprises an inner ring-like part 5a, intended to abut the outer rock surface ph the inner plate 2, an outer ring-like part 5b, intended to abut . against the hire rock surface on the outer plate 1, a plurality of radial arm portions Sc, which connect the inner and the outer ring-like portion to each other and a plurality of sectoral openings 5d with resp. parts connected to each other by welding (see Fig. 2). The diameter of the Ira used can vary between 0.3 and 0.5 mm. Alternatively, the body may be made of a metal plate, preferably of stainless steel, having a thickness of about 9.5 mm, by embossing or punching it in the desired shape. In this case, the frame resp. parts em said. Desired, connected to each other genoxn welding.

Med stommen 5 inskjuten pa plats i det ringformiga mellanrummet 3 kommer nden av det inre platrdret 2 att utvandigt stracka sig utanfOr stommen 5 och dess yttersta del skjuter fOretradesvis ut framfor den yttersta del-en av det yttre pldtroret 1 en kart bit, SOM kan uppga till ca 5 mm. With the frame 5 inserted in place in the annular space 3, the end of the inner plate tube 2 will extend externally outside the frame 5 and its outer part preferably protrudes in front of the outer part of the outer plate tube 1 a short distance, which may be to about 5 mm.

Sedan .det yttre platroret 1 MAI koncentriskt fixerat i forhallande till det inre platrOret 2 med tillhjalp av den framre pluggen 4 och stommen 5 sasom ovan beskrivit& och sasom framgar av fig. 1, kan en rnangd finkrossat eller pulvriserat keramiskt karnbranslematerial, sasom urandioxid (UO2)-pulver, hallas i det ringformiga utrymmet 3 genom. Oppningarna 5d i stommen 5, tills pulvret fyller upp det utrymme som begransas av platarna, den framre pluggen oeh stommen. FOr att erhalla ett karnbransleelement med hOg densitet ar det onskyart all gra totaldensiteten for det ifyllda hranslematerialet sa hog: som mojligt. Pla'tirna med det daremellan inneslutna branslematerialet kunna darfOr vibreras med flagon lainplig vibreringsanordning for att Tka branslematerialets hoppackade tat-bet hg. Pa sá salt bar det utrymme 3, som begransas av de tva. platarna 1 och 2, den framre pluggen 4 och stommen 5 fyllts ut med branslematerial i kompakt form med hog hoppackad tathet. Since the outer plate 1 MAI is concentrically fixed in relation to the inner plate 2 by means of the front plug 4 and the body 5 as described above and as shown in Fig. 1, a finely crushed or powdered ceramic core fuel material, such as uranium dioxide (UO 2) ) powder, is poured into the annular space 3 through. The openings 5d in the body 5, until the powder fills the space bounded by the plates, the front plug and the body. In order to obtain a nuclear fuel element with a high density, it is uncommon for the total density of the filled mill material to be as high as possible. The plates with the fuel material enclosed therebetween can therefore be vibrated with a flap-like vibrating device to remove the packed material of the fuel material. On that salt there was space 3, which is bounded by the two. plates 1 and 2, the front plug 4 and the frame 5 are filled with fuel material in a compact form with a high packed density.

Darefter inskjutes en bare plugg 6, pa nedan. narmare beskrivet satt, i det ringformiga utrymmet mellan det yttre .och det inre platroret, tills den stater mot stommen 5 pa salt som visas i fig. 3. Den bakre pluggen 6, som fOretradesvis bestar av rostfritt stal, liar en ytterdiameter, som i huvudsak ãr lika med innerdiametern for det yttre platrOret 1 och en central oppning 6a.--6b, vars diameter i huvudsak ar lika med ytterdiametern fOr det in-re platroret. Med pluggen 6 inpassad i utrymmet 3 i det i fig. 3 visade laget, .stracker sig anden av den inre platen 2 delvis ut genom Oppningen 6a-6b for axiell glidrorelse och lamnar ett toniru.m 6b mellan andytan av den .forra och bottnen .av den senare. Tomrummet 6b sakerstaller, att den inre platen 2 och en inn-Li denna inford karna, pa salt som i detalj kommer att beskrivas nedan, far mojlighet att utstrackas i tillfredsstallande grad under den efterfoljande roterande sanksmidningen. Then insert only a plug 6, on below. more specifically, sat, in the annular space between the outer and inner plates, until it faces the body 5 of salt shown in Fig. 3. The rear plug 6, which preferably consists of stainless steel, has an outer diameter which in is substantially equal to the inner diameter of the outer plate 1 and a central opening 6a .-- 6b, the diameter of which is substantially equal to the outer diameter of the inner plate. With the plug 6 fitted in the space 3 in the layer shown in Fig. 3, the spirit of the inner plate 2 extends partly out through the opening 6a-6b for axial sliding movement and leaves a tone space 6b between the front surface of the front and the bottom. .of the latter. The void space 6b ensures that the inner plate 2 and an inner part thereof, on salt, which will be described in detail below, are allowed to extend satisfactorily during the subsequent rotating forging.

Ett raelement, sona skall genomga roterande sdnksmidning kompletteras genom att mu-ti det inre platroret 2 forses hied en karna 7, med en diameter i huvudsak lika med ifragavarande platrors innerdiameter. Sasom tidigare poangterats maste karnan nodvandigtviscroras av ett material med tillracklig nisk mekahallfasthet f Or att kunna motsta en. hOg spanningspakanning som foljd air roterande sanksmidning och fOr att kunna uppbara in:sidan av den inre platen utan nagon deformation air densamma under den rote-rand e sank smid.ningen. A raw element, the zones to undergo rotational sink forging is supplemented by forcing the inner plate 2 into a core 7, with a diameter substantially equal to the inner diameter of the plates in question. As previously pointed out, the core must necessarily be viscous of a material having sufficient mechanical strength to be able to withstand one. high tension gasket which follows air rotating forging and to be able to support the side of the inner plate without any deformation air the same during the rotating edge forging.

— — Tillfredsstallande resultat erhallas da karnan har en elasticitetsmodul av minst 5X3 kg/mm2 och en flytgrans av minst 5 kg/mm2. Vidare erfordras det, att karnan med latthet skall •kunna avlagsnas fran den inre platen efter slutford roterande sanksmide For detta andamal skall materialet i karnan ha en smaltpunkt ,som är lagre an smaltpunkten for materialet i saval den yttre som den inre platen, varigenom karnan latt kan avlagsnas fran det inre platroret genom utsmaltning. Alternativt skall karnan vara mera lattlOslig i en mineralsyra an vart och ett av platmaterialen. Med tvfi plfitar av rostfritt stal, skall materialet i karnan nodvandigtvis ha en smaltpunkt understigande 1200° C. Satisfactory results are obtained as the karnan has a modulus of elasticity of at least 5X3 kg / mm2 and a yield strength of at least 5 kg / mm2. Furthermore, it is required that the karnan should be easily removed from the inner plate after final rotating forging. For this purpose, the material in the karnan must have a melting point which is lower than the melting point of the material in both the outer and the inner plate, whereby the karnan can be removed from the inner plate by melting. Alternatively, the core should be more readily soluble in a mineral acid than any of the plate materials. With two stainless steel pellets, the material in the core must necessarily have a melting point below 1200 ° C.

Exempel pa lampliga karnmaterial aro zinklegeringar, magnesiumlegeringar, aluminiumlegeringar, tennlegeringar, nickel °eh dess legeringar, kopparlegermgar, jarnlegeringar, silverlegeringar, kadmfum och dess legeringar, antimon och dess legeringar och liknande. Exempel pa sadana material, som arc att fOredraga är en zinklegering bestaende .av 4,1 % aluminium, 0,08 % magnesium och resten zink, med en elastieitetsmodul air 7600 kg/ min.2 och en flytgrans av 9,5 kg/mm2 vid 0,013 % avvikelse, en legering av 95 % koppar och 5 % zink, en legering av 85% .koppar och 15 %, zink och en legering av 70 % koppar och 30 % zink. Dessa koppar-zink legeringar ha en elasticitetsmodul av 13,700, 13,700 och 11,240 resp. en flytgrans .av resp. 7,0, 7,0 och 9,8 kg/mm2 yid resp. 0,13 % avvikelse. I allmanhet kunna legeringar, innehallande 3-6 % aluminium, 0-5 % koppar, 0,013-0,1 % magnesium och resten zink anvandas med tillfredsstallande resultat. Examples of suitable core materials are zinc alloys, magnesium alloys, aluminum alloys, tin alloys, nickel and its alloys, copper alloys, iron alloys, silver alloys, cadmium and its alloys, antimony and its alloys and the like. Examples of such materials which are preferred are a zinc alloy consisting of 4.1% aluminum, 0.08% magnesium and the remainder zinc, with a modulus of elasticity of 7600 kg / min.2 and a yield strength of 9.5 kg / mm2. at 0.013% deviation, an alloy of 95% copper and 5% zinc, an alloy of 85% copper and 15%, zinc and an alloy of 70% copper and 30% zinc. These copper-zinc alloys have a modulus of elasticity of 13,700, 13,700 and 11,240, respectively. a floating boundary .of resp. 7.0, 7.0 and 9.8 kg / mm2 yid resp. 0.13% deviation. In general, alloys containing 3-6% aluminum, 0-5% copper, 0.013-0.1% magnesium and the remainder zinc can be used with satisfactory results.

Forutom en enkel .kropp av nagon av de ovan just nanuida metallerna, kan karnan oeksa utbildas av koneentriska skikt av tva eller flera metaller, lampligen utvalda bland de ovannamnda. Kaman kan dessutom oeksa utbildas enom bekladnad av en planotrad, innehallande 0,65-0,95 % C och 0,12-0,32 % Si och med en elasticitetsmodul ay 21,000 kg/mm2 och med en flytgrans ay 80-150 kg/mm2 med en zinklegering eller liknande. In addition to a simple body of any of the above-mentioned nanoid metals, the karnan oeksa may be formed by concentric layers of two or more metals, suitably selected from the above-mentioned. Kaman can also be trained by coating with a blank line, containing 0.65-0.95% C and 0.12-0.32% Si and with a modulus of elasticity of 21,000 kg / mm 2 and with a buoyancy of 80-150 kg / mm2 with a zinc alloy or similar.

Ett .satt ,att framstalla kaman kommer nu att beskrivas i samband med anvandingen av en zinklegering air den forstnamnda sammansattningen. Ett got av en sadan legering smaltes oeh gjutes i form ay en rund stang. Stang-en reduceras darefter i diameter t. ex. genom sanksmidning, tills den precis passar in i det inre pla.troret. A method of producing the cam will now be described in connection with the use of a zinc alloy in the former composition. A cast of such an alloy was melted and cast into a round rod. The rod is then reduced in diameter e.g. by forging, until it fits snugly into the inner plate.

Ett raelement, framstallt pa ovan beskrivet satt, kan nu Overforas till en maskin for roterande sanks,midning 'rued automatiska matningsanordningar (ej visade). Sanksmidningen maste paborjas i den ande av rfielementet, dar den framre pluggen 4- fast forbundits med den yttre och hire platen 1 resp. 2, dvs. den v5.nstra delen darav, sasorn framgar av fig. 3, och darefter suceessivt fortskrida i riktning mot den .andra anden eller den hogra delen ,av detsamma sasom visas i fig. 3. Sanksmidningen skall jute pabOrjas i hOgra anden. A raw element, manufactured in the manner described above, can now be transferred to a machine for rotating sinks, centering and automatic feeding devices (not shown). The sink forging must be drilled in the spirit of the rfielement, where the front plug 4- is fixedly connected to the outer and hire plate 1 resp. 2, i.e. the left part thereof, the sasor is shown in Fig. 3, and then successively progresses in the direction of the other spirit or the right part, of the same as shown in Fig. 3. The sink forging shall be jute pabOrjas in the right spirit.

I det inledande skedet av den roterande sanksmidnings op er ationen, sammanpressas massan av branslematerialet och pa motsvarande satt minskar det yttre platrOret 1 i diameter. Sedan densiteten for det sammanpressade branslet natt sitt mattnadsvarde, forlanges inte blott kaman 7 utan aven det hire platroret 2 pa ett anmarkningsvart satt och plartarnas vagtjocklek reduceras. Forlangningen resulterar i wdell strackning av raelementet. I enlighet med uppfinningen är den bakre pluggen 6 .anordnad for att gild-hart uppbara anden ay karnan 7 i oppningen 6a av densamma. Detta tillater karnan att fritt forlangas utan att nagon spanning upptrader i .densamma. Om ett UO2-element av ihaligt slag framstalles med tillhjalp ay roterande .sanksmidning, kommer elementet att forlangas 15-30 % vid en arbetsgrad av %, varjamte aven raelementet i sin helhet kommer att forlangas. I detta sammanhang fir det att foredraga, att oppningen 6a-6b i den bakre pluggen. 6 liar ett djup motsvarande ,storleksordningen 10/100 ay den totala langden L for det yttre platrOret 1 och sa att langderna av den del ay det inre platroret 1 och foljaktligen av karnan 7, som i borjan stracker ,sig in i oppningsdelen 6a, och langden av den tomma Oppningsdelen 6b, vardera aro c:a 5/100 av den totala langden L. In the initial stage of the rotary sink forging operation, the mass of the fuel material is compressed and correspondingly the outer plate 1 decreases in diameter. Since the density of the compressed fuel at night reaches its matting value, not only the cam 7 but also the hair plate 2 is required in a remarkably black manner and the carriage thickness of the plates is reduced. The elongation results in wdell stretching of the raw element. In accordance with the invention, the rear plug 6 is arranged to validly support the spirit of the core 7 in the opening 6a thereof. This allows the core to be freely demanded without any tension appearing in the same. If a UO2 element of the continuous type is manufactured with the aid of rotary forging, the element will be required 15-30% at a degree of operation of%, and also the raw element as a whole will be required. In this context, it is preferable that the opening 6a-6b in the rear plug. 6 is a depth corresponding to the order of 10/100 of the total length L of the outer plate 1 and said that the lengths of the part ay the inner plate 1 and consequently of the core 7, which initially extends, extend into the opening part 6a, and the length of the empty opening part 6b, each aro about 5/100 of the total length L.

Da det ifragavarande raelementet utsattes f Or roterande sanksmidning uppbyggas snabbt koneentrerade spanningar i det sammanpressade branslet inuti elementet. Som en foljd air dessa spanningar kommer en makroskopisk och mikroskopisk omdaning av kristallstrukturen att intraffa i det sammanpressade branslet. Med andra ord sfi. gehastigt upprepade, dynamiska spanningar till foljd ay roterande •sanksmiclning upphov till bade omflyttning av partiklar och atarnisk diffusion inuti det sammanpressade branslet, varigenom packningen gores mycket tat och sintrad i form ay en fast kropp med hog densitet. t. ex. kommer den slutliga densiteten, om en UO2-paokning endast utsattes for kall, roterande .sanksmidning pa ovan beskrivet salt i och for bildning av ett keramiskt bransleelement, att uppna ett varde som. med 85 % overstiger den teoretiska densiteten. Med en sadan roterande sanksmidning genomford vid en temperatur av mindre an 2/3 av den normala sintringstemperaturen under flera minuter, kan UO2-fyllningen mellan den yttre och den inre platen ha en densitet, i huvudsak lika med ,densiteten for ett UO2-korn, framstallt enligt ,det konventionella pulvermetallurgiska forfarandet. Experiment visa, att hail sanksmidning och varm sanksmaidning vid en temperatur av 800-1100° C ge — — maximala sanksmidningsdensiteter som motsvara 91 resp. 95 % av de teoretiska vardena. As the raw element in question is subjected to rotating forging, concentrated concentrations quickly build up in the compressed industry within the element. As a result of these stresses, a macroscopic and microscopic transformation of the crystal structure will occur in the compressed industry. In other words sfi. rapidly repeated, dynamic stresses to follow ay rotating • sankmiclning giving rise to both particle displacement and atarnic diffusion within the compressed industry, whereby the gasket is made very tat and sintered in the form of a high density solid body. e.g. For example, the final density, if a UO2 increase is only subjected to cold, rotational sinking on the salt described above to form a ceramic fuel element, will reach a value which. by 85% exceeds the theoretical density. With such a rotating sink forging through at a temperature of less than 2/3 of the normal sintering temperature for several minutes, the UO2 charge between the outer and inner plates may have a density substantially equal to the density of a UO2 grain. prepared according to the conventional powder metallurgical process. Experiments show that hail sink forging and hot sink forging at a temperature of 800-1100 ° C give - - maximum sink forging densities corresponding to 91 resp. 95% of the theoretical values.

Under den roterande sanksmidningsoperationen overfores till den inre platen hfiga dynamiska spanningar genom den inuti platen :anordnade hoghallfasta karnan. Detta sakerstaller, att den inre platen bevarar sin jamna vaggtjoeklek, en exakt cirkular form och en tillfredsstallande ratlinjighet pa samma satt som den yttre platen. Om ett ra.element utan karna skulle utsattas for roterande sanksmidning skulle genomskarningen for det inre platroret Ifitt deformeras och antaga for-men av en oregelbunden cirkel. Man kan dãrfOr aldrig vanta sig, att .det skall vara mojligt att astadkomma ett ihaligt karnbransleelement, som har sin centrala oppning utbildad i form av en exakt cirkel. Det fir likasa uppenhart, att under roterande sanksmidning sprickor komma att uppstâ i de oregelhundet deformerade delarna av "den inre platen 2, vilket resulterar i att det hlir omojligt att pa ett tillfredsstallancle satt overfora det mellan den yttre och den inre platen sanrmanpressade branslematerialet i fast form. During the rotary sink forging operation, high dynamic voltages are transmitted to the inner plate through the hoghall-fixed core arranged inside the plate. This ensures that the inner plate retains its even cradle thickness, an exact circular shape and a satisfactory straightness in the same way as the outer plate. If a raw element without the tubes were to be subjected to rotating forging, the cut-through for the inner plate Ifitt would be deformed and assume the shape of an irregular circle. It can therefore never be expected that it will be possible to provide a solid core fuel element which has its central opening formed in the form of an exact circle. It is also obvious that during rotating forging cracks will appear in the irregularly deformed parts of the inner plate 2, which results in it being impossible to transfer in a satisfactory manner the compressed fuel material compressed between the outer and inner plates in solid form.

Med den yttre och den inre platen afford i rostfritt stal, fororsakar utfallningen av karbider spanningskoncentrationer i de delar av platarna dar karhiderna utfallts under den roterande sank:smidningsoperationen. Denna spanningskoncentration framkallar och beframjar tillvaxten av mikroskopiska sprickor. Den successivt genomforda roterande sanksmidningen fororsakar, att ytterligare spanningar koncentreras i narheten av de mikroskopiska sprickorna, varigenom sekundara mikroskopiska sprickor framkallas och tillvaxten av de primara och de sekundara mikroskopiska .sprickorna till ,stora allvarliga sprickor beframjas. Pa grund harav kan ett platholje, som innehaller mikroskopiska sprickor, inte anvandas for att beklada ett karnbransleelement. Det har nu visat sig, att ett platmaterial, innehallande kol i en mangd understigande 0,02 %, pa ett effektivt salt skyddas mot utfallningen av karbider, varigenom de nyss ovan beskrivna nackdelarna kunna undvikas, vid framstallningen av de overlagsna produkterna enligt uppfinningen. With the outer and inner plates afforded in stainless steel, the precipitation of carbides causes stress concentrations in the parts of the plates where the carbides precipitated during the rotating sink: forging operation. This concentration of stress induces and promotes the growth of microscopic cracks. The successive rotating forging causes additional stresses to be concentrated in the vicinity of the microscopic cracks, thereby inducing secondary microscopic cracks and promoting the growth of the primary and secondary microscopic cracks into large severe cracks. Due to this, a plate oil containing microscopic cracks cannot be used to line a nuclear fuel element. It has now been found that a plate material, containing carbon in an amount of less than 0.02%, on an effective salt is protected against the precipitation of carbides, whereby the disadvantages just described above can be avoided, in the preparation of the superior products according to the invention.

Sedan den roterande sanksmidningen slut-forts, kan karnan 7 avlagsnas frail det sanksmidda elementet, antingen genom upphettning och smaltning av karnan eller genom upplosning av denna i nagon lamplig mineralsyra, vilket som nu fir att foredraga. Dfirefter avskaras ,det .sanksmidda elementets hada andar, samt fOrseglas darefter Ater genom svetsning, vilket resulterar i ett ihaligt karnhransleelement, sadant detta framgar av fig. 4. I fig. 4 visas en sanksmidd, fortatad kropp av ett karnbransleelement 8, sadant delta ar belaget mellan en yttre och en inre plat, 1 resp. 2 i intim kontakt med dessa. Av fig. framgar ocksa., att det fardiga ele mentet har en ytterdiameter som är minclre an begynnelsediametern for den yttre platen. After the rotating forging is completed, the core 7 can be removed from the forged element, either by heating and melting the core or by dissolving it in some suitable mineral acid, which is now preferred. Thereafter, the hot spirits of the forged element are cut off, and then sealed again by welding, which results in a hollow core ring element, as shown in Fig. 4. Fig. 4 shows a sink forged, reinforced body of a core fuel element 8, such that delta ar coated between an outer and an inner plate, 1 resp. 2 in intimate contact with these. It can also be seen from Figs. That the finished element has an outer diameter which is smaller than the initial diameter of the outer plate.

Foljande exempel avse att belysa tillampningen av uppfin.ningen. The following examples are intended to illustrate the application of the invention.

Exempel 1. Sasom tidigare beskrivits i samband med fig. 1 och 3, svetsades ett yttre cylindriskt rOr av AISI 304 L rostfritt stal, riled en ytterdiameter av 12 mm, en vaggtjoeklek av 0,5 mm oh en langd av 1000 mm, i ena anden koncentriskt i fOrhallande till ett inre cylindriskt ror av 304 L rostfritt med en ytterdiameter av 6,5 mm, en vaggtjocklek av 0,5 mm och en langd av 1050 mm med tillhjalp av en framre plugg av summa stalsort. En •stomme av en tract; sisom tidigare beskrivits, stodjande mot saval den inre vaggytan av det yttre roret som mot den yttre vaggytan av det inre roret, gran sade intill den andra anden av det yttre roret pa ett avstand av c :a 52 mm, matt fran den narmsta Auden av det inre roret. Den inre vaggytan av ,det yttre roret och de yttre och inre vaggytorna av det inre roret hade pa for-hand gjorts slata .genom mekanisk polering och kemisk eller elektrolytisk polering, varigenom sfidana ytdefekter som rispor, slagg, sprickor etc. avlagsnades. Example 1. As previously described in connection with Figures 1 and 3, an outer cylindrical tube of AISI 304 L stainless steel was welded, having an outer diameter of 12 mm, a cradle thickness of 0.5 mm and a length of 1000 mm, in one spirit concentrically in relation to an inner cylindrical tube of 304 L stainless steel with an outer diameter of 6.5 mm, a cradle thickness of 0.5 mm and a length of 1050 mm with the aid of a front plug of total steel. A • frame of a tract; as previously described, standing against the inner rock surface of the outer rudder as well as against the outer rock surface of the inner rudder, spruce said next to the other end of the outer rudder at a distance of about 52 mm, matt from the nearest Auden of the inner rudder. The inner rock surface of the outer tube and the outer and inner rock surfaces of the inner tube had been previously smoothed by mechanical polishing and chemical or electrolytic polishing, whereby such surface defects as scratches, slag, cracks, etc. were removed.

En mangd UO2-pulver halides i det mellan de hada roren bildade, ringformiga utrymno.et genoan oppningarna i stomTnen, tills pulvret fyllde upp utrymmet, begrunsat av de bkda roren, den framre pluggen och stommen med den hoppackade densiteten for det ifylida pulvret uppgaende till 70 % av sitt teoretiska varde, efter vibrering av detsamma med tillhj alp av en lamplig vihreringsanordning. A quantity of UO2 powder is halided in the annular space formed between the hot tubes through the openings in the body, until the powder fills the space, justified by the bent tubes, the front plug and the body with the packed density of the filled powder amounting to 70% of its theoretical value, after vibration of the same with the aid of a suitable vibrating device.

Darefter fastsvetsades den bakre pluggen thsom tidigare beskrivits vid det yttre rorets andra ande pa tidgare beskrivet salt Den svetsade pluggens tomma oppningsdel hade en langd av c :a 52 mm. Then the rear plug as previously described was welded to the second spirit of the outer tube on the previously described salt The empty opening part of the welded plug had a length of about 52 mm.

En karna, framstalld av en zinklegering, innehallande 4,1 % Al, 0,04 % Mg och resten zink inpassades i det inre roret sasom visas i fig. 3, for att pa sa satt bilda ett raelement. Kaman framstalldes genom smaltning av ett got nv den nyss namnda zinklegeringen och genom att gjuta den smalta legeringen till en stang med en diameter av 12,5 mm. Stang-en underkastades darefter sanksmide fOr att reducera .dess tvarsektion, tills den just kunde inpassas i det inre Det pa sa satt framstallda ra.elententet utsattes darefter f8r roterande sanksmidning f8r att fOrtata och ,sintra UO2-pulvret. Den fasta UO2-kroppen har en densitet corn motsvarar 89 % av det teoretiska vfirdet. A core, made of a zinc alloy, containing 4.1% Al, 0.04% Mg and the remainder of zinc was fitted into the inner tube as shown in Fig. 3, so as to form a raw element. The cam was made by melting a cast nv the just mentioned zinc alloy and by casting the narrow alloy into a rod with a diameter of 12.5 mm. The rod was then subjected to a forging to reduce its cross-section until it could be fitted into the interior. The raw element thus produced was then subjected to rotating forging to preform and sinter the UO2 powder. The solid UO2 body has a corn density corresponding to 89% of the theoretical value.

Kaman avlfigsnades darefter Iran den sanksmidda produkten genom utsmaltning. Kaman was subsequently deported to Iran for the sunken forged product by smelting.

De hada andarna pli. det sanksmidda elementet avskuros och forseglades darefter Ater genom svetsning i odh for fullbordan av ett ihâligt karnbransleelement med hog densitet. They had the spirits pli. the sunken forged element was cut off and then sealed again by welding in odh for completion of a hollow, high density nuclear fuel element.

C— — Betraffande dimensionsnoggrannheten for produkter som genomgalt sanksmidning kan namnas, att det yttre roret hade en ytterdiameter av 9,5 + 0,02 mm, en vaggtjocklek av 0,15 + 0,02 ram och att det inre roret hade en ytterdia_meter ,av 5,2 + 0,02 ram och en vaggtjoeklek av 0,48 + 0,02 mm. C— - Concerning the dimensional accuracy of products that have undergone sink forging, it can be mentioned that the outer tube had an outer diameter of 9.5 + 0.02 mm, a rock thickness of 0.15 + 0.02 frame and that the inner tube had an outer diameter, of 5.2 + 0.02 frame and a cradle thickness of 0.48 + 0.02 mm.

Det fardiga .elementet var i huvudsak rakt, atted en avvikelse fran rak referenslinje av mindre an 0,25 mm per meter. The finished element was substantially straight, with a deviation from the straight reference line of less than 0.25 mm per meter.

Exempel 2. Ett ytterrEir och ett innerr5r framstalldes av saTnma stal som det i exempel 1 anvanda och forfarandet enligt exempel 1 upprepades med undantag av, .att det yttre raret hade en ytterdiameter av 20 mm, en vaggtjocklek av 1,0 tmm och en Ifingd av 200 aim saint att det inre r8ret hade en ytterdiameter av mm, en vaggtjocklek av 1,0 Tam och en langd av 230 mm. Pk motsvarande salt andrades dimensionerna for en stomme, pluggar och en karna sã att de passade till de nya rorens dimensioner. Example 2. An outer tube and an inner tube were made of the same steel as that used in Example 1, and the procedure of Example 1 was repeated except that the outer tube had an outer diameter of 20 mm, a rock thickness of 1.0 mm and a Ifingd. of 200 aim saint that the inner tube had an outer diameter of mm, a rock thickness of 1.0 Tam and a length of 230 mm. Pk corresponding salt changed the dimensions of a frame, plugs and a core so that they fit the dimensions of the new pipes.

Det anvan.da UO2-pulvrets hoppackade densitet uppgick till 70 % air den teoretiska densiteten och den sanksmidda densiteten till 88 %. The compressed density of the UO2 powder used was 70% of the theoretical density and the forged density was 88%.

Det Isanksmidda ytterroret hade en ytterdiameter av 16,65 + 0,02 mm ooh en vaggtjocklek av 0,98 + 0,02 mm under det att det sanksmidda innerroret bade en ytterdiameter air 7,56 + 0,02 nnn och en vaggtjocklek air 0,98 + 0,02 931111. The Sank forged outer tube had an outer diameter of 16.65 + 0.02 mm ooh a rock thickness of 0.98 + 0.02 mm while the sank forged inner tube had an outer diameter air 7.56 + 0.02 nnn and a rock thickness air 0 , 98 + 0.02 931111.

Det fardiga elementet var i huvudsak lika rakt som elementet enligt exempel 1. The finished element was substantially as straight as the element of Example 1.

Av det ovanstaende framgar, att ihaliga karnbransleelement i enlighet med uppfinningen Mitt kunna framstallas med hog produktionskapacitet och till lag kostnad, vilka element ha en hog sanksmidd densitet f Or det kerainiska branslematerialet .ocli noggranna dimensioner av ytter- och innerdiametrarna ailed en exakt cirkular genomskarning. From the above it appears that solid core fuel elements in accordance with the invention can be manufactured with high production capacity and at low cost, which elements have a high immersion density for the keranine fuel material and accurate dimensions of the outer and inner diameters with an exact circular cut.

Aven om uppfattningen beskrivits under anvandning av I102 som karnbranslematerial, al- del att forsta, att uppfinningen pa liknande ,salt ar tillompbar for framstallning av ihAliga keramiska eller "cermet" karnbransleelement air hog densitet, fran keramik och cermet, bildade av oxider, karbider eller sill-cider av konventionella karnbranslematerial, sasom wan, torium, plutonium °eh liknande, eller av lampliga blandningar darav. Although the concept has been described using I102 as a nuclear fuel material, it is to be understood that the invention, like salt, is applicable to the production of whole ceramic or "cermet" high density nuclear fuel elements, from ceramics and cermets, formed from oxides, carbides or herring ciders of conventional nuclear fuel materials, such as wan, thorium, plutonium and the like, or of suitable mixtures thereof.

Eftersom olika forandringar av det ovan beskrivna forfaran.det kunna goras liksom olika utforingsformer av uppfinningen, utan att for den skull meningen med och Tamen for upplintringen frangas, shall det papekas, att alit vad scan framgar av beskrivningen eller visas pa bifogade ritning endast är att betrakta sasom tjanande till att belysa uppfinningen och inte ar att uppfatta som flagon begransning. Since various modifications of the process described above may be made, as well as various embodiments of the invention, without departing from the spirit and scope of the invention, it should be noted that whatever scan appears from the description or shown in the accompanying drawings is merely considered as serving to illustrate the invention and not to be construed as flag limitation.

Claims

Patent claim:

1. Salt to produce a hollow ceramic or cermet nuclear fuel element high density for nuclear reactors, characterized in that an annular space is filled but: an outer cylindrical plate and an inner cylindrical plate concentrically arranged with a ceramic or cermet core fuel material and then closes the annular space, fills the inner plate with a core, which has a modulus of elasticity of at least 5 X 3 kgimm2 and a yield strength of at least 5 kg / mm2, the material in said core either having a melting point of Or If each of the material of the inner and outer tubes or also is less readily soluble in a mineral acid, the salt-forming unit thus formed is subjected to rotating sink forging, to continue and sinter the filled well material to high density and thereafter. removes the karnan from the submerged product either by melting it or by dissolving the nsamma in the mineral acid.

2. A set according to claim 1, characterized in that a stainless steel containing carbon in an amount of at most 0.02% by weight is used as the material in each of the plates.

3. Set according to patent claims 1 and 2, characterized in that the outer plate is free to extend in relation to the core during the rotating forging operation.

4. A kit according to claims 1-3, characterized in that the material in the core is made of a zinc alloy, containing 3-6% aluminum, at most 5% copper and 0.03-0.1% magnesium. AnfOrda publications: United Nations international conference on the peaceful uses of atomic energy. 2. 1958. Geneva. Proceedings. Vol. 6. Geneva 1958, pp. 359, 602-603.