CN101019193A - Multi-layered ceramic tube for fuel containment barrier and other applications in nuclear and fossil power plants - Google Patents

Abstract

A multi-layered ceramic tube to contain fissile fuel within a nuclear power reactor, particularly as cladding layer for a fuel rod in a nuclear power plant or reactor, having an inner layer of high purity beta phase stoichiometric silicon carbide, a central composite layer of continuous beta phase stoichiometric silicon carbide fibers, and an outer layer of fine-grained silicon carbide, to improve initial crack resistance, stiffness, ultimate strength, impact resistance and thermal shock resistance.

Description

The multi-layered ceramic tube that in nuclear and fossil power plants, is used for fuel containment barrier and other application

The cross reference of related application

[0001] the application requires the U.S. provisional application series No.60/577 of submission on June 7th, 2004 according to 35U.S.C. joint 119 (e), the rights and interests of the U.S. patented claim No.______ that on June 6th, 209 and 2005 submitted to, described document is incorporated herein by reference in full at this.

Statement about federal funding research

[0002] the technology part of describing among the application is according to the SmallBusiness Innovative Research Grant-Grant#DE-FG02-01ER83194 exploitation from USDOE.

Background

[0003] the present invention relates to be used for comprising the device of easy fission fuel at nuclear-power reactor.In many present nuclear reactors, fuel package is contained in the sealed metal tube that is commonly referred to " fuel can (cladding) ", and it is made up of zircaloy or steel alloy usually.The design fuel can is not released into cooling medium to guarantee all radgass and solid fission product being retained in pipe neutralization during the normal running of reactor or during imaginabale accident.The fault of fuel can cause heat subsequently, and hydrogen and final fission product are to the release of cooling medium.

[0004] it is known in the art adopting the problem of conventional fuel involucrum.For example, metal casing is soft relatively, weares and teares and abrasion with tending to when contacting with fragment, and described fragment enters coolant system sometimes and contacts fuel.Such wearing and tearing and abrasion can cause the breach on metal containment (containment) border and the release subsequently that fission product enters cooling medium sometimes.In addition, metal casing and the hot water themopositive reaction that surpasses 2000  (1093 ℃) therefore increase other heat to the fission-product decay heat amount that is produced by nuclear fuel.From this other heat of involucrum can the deterioration accident seriousness and duration, as taking place at Three Mile Island.

Many metals also lose intensity during the high temperature that [0005] takes place during being exposed to accident.For example, during design considerations coolant loss accident (Loss of Coolant Accident), temperature in the nuclear power for civil use factory can reach high and cause metal such as zirconium class alloy loss their intensity of great majority and because inner fission gas pressure such as balloon expansion to 2200  (1204 ℃) and these high-temperatures.The ANALYSIS OF COOLANT FLOW during the urgent cooling stage of obstruction accident is tended in this expansion.Similarly, cause the loss-of-flow accident of film boiling on the fuel element surface to produce the short duration increase of metallic surface temperature and the incipient fault of unacceptable loss of strength and fuel element.Zirconium alloy cladding tends to oxidation and becomes fragile and this causes premature failure during the typical reaction introducing accident after the long-time exposure to cooling medium, wherein fuel particle adds immersion heater than involucrum, causes the internal mechanical load and the fault of embrittlement metal casing.

[0006] serious consequence for avoiding taking place during accident, the fuel of all metal casings must be operated with the film boiling during preventing loss-of-flow accident under basic departure nucleate boiling (DNB) safety coefficient.This operational constraints limit average reactor core thermoflux and therefore the maximum of nuclear reactor can allow thermal power.In addition, for the oxidation of avoiding zirconium alloy cladding with become fragile, present federal control criterion limits the exposure quantity of uranium fuel rod of such metal casing to being not more than 62,000 megawatts-sky per metric ton (mwd/t) uranium fuel.Referring to NUREG/CR-6703, " EnvironmentalEffects of Extending Fuel Burnup Above 60 GWD/MTU " (January calendar year 2001).

[0007] attempts to improve fuel can, with expenditure during the reduction reactor accident and increase safety.For example, assigning in the U.S. of Feinroth patent No.5, in 182,077, the infringement that during the inventor proposes to adopt metal alloy in continuous fiber ceramic composite (CFCC) the alternative fuel involucrum with the mitigation accident metal casing is applied.The exemplary compound substance that proposes is made by continuous alumina fiber and alumina substrate.These compound substances overcome some above-mentioned defectives of metal casing, but they self certain their application of this drawbacks limit.

Therefore [0008] for example, alumina composite material can lose their intensity under neutron irradiation, limits them and bears the machinery that applies during the accident and the ability of heating power.Equally, U.S. patent No.5, the alumina composite material that proposes in 182,077 comprises the 10-20% interior porosity, because need guarantee the appropriate fault mode under mechanical load.Yet this porosity can cause compound substance and can see through fission gas, therefore allows fission gas by the unacceptable leakage of involucrum to cooling medium.Referring to as Gamma Engineering NERI Report 41-FR, " Continuous Fiber Ceramic Composite (CFCC) Cladding forCommercial Water Reactor Fuel " (April calendar year 2001), obey the Grant No.DE-FG03-99SF21887 of USDOE.

[0009] refining of these alumina composite materials, is described among the American Nuclear Society Proceedings-ICAPP conference (in June, 2002) at " Progress in Developing an Impermeable; High TemperatureCeramic Composite for Advanced Reactor Clad Application " by people such as H.Feinroth.People such as Feinroth propose to substitute U.S. patent No.5 by double-deck carborundum tube, 182, the alumina composite material of describing in 077, wherein internal layer is used as the impermeable shielding of the high density of fission gas, with skin as ceramic composite, this ceramic composite can bear the influence of heat under the high temperature and physical shock and not have fault.Yet the pipe of proposition has several defectives, and this defective is disturbed the unfailing performance in the existing commercial water reactor, or is used to make water, gas, or the high-temperature reactor of liquid metals cooling medium.

[0010] for example, the weaving fiber tow in the composite layer comprises big space, and physical strength, the water-fast obstruction that requires in thermal conductivity and the can material are disturbed in this space.Big space is intrinsic in the fibre bundle knitting skill of being used by people such as Feinroth.Equally, the integral tube that is used for the sintering of interior layer comprises sinter additives such as boron or aluminium oxide, and their disturb pipe to bear neutron irradiation and do not have the ability of excessive swelling and fault.Such sinter additives is necessary for the successful manufacturing of sintered sic pipe.

[0011] be " α " crystallization phase silit in the integral tube of the sintering of interior layer by humans such as Feinroth, it is different from the β phase fiber that is used to form composite layer on crystal structure.Similarly, with comprise β mutually the composite layer of fiber compare, interior layer experiences different swelling rates under neutron irradiation, cause possible delamination during the neutron irradiation.Referring to R.H.Jones, " Advanced Ceramic Composites for High Temperature FissionReactors ", Pacific Northwest Laboratory Report NERI-PNNL-14102 (in November, 2002).

[0012] in addition, the composite layer that is used by people such as Feinroth is from pre-Woven fabric preparation and be not subjected to stress in advance, as when experiencing internal pressure from the global transfer burden requirement.The result is, if with the fault stress that reaches it in integral body before composite layer can share comparing of load, integral body more may break down under low internal pressure.This shows that in Figure 12 it is two pipes of internal pressure in Oak Ridge National Labortory experience test wrapper relatively.Identical SiC integral tube is used for two pipes, but adopts multiple tube, and integral body is strengthened to form multiple tube by composite layer.Multiple tube is stronger than independent integral body, the benefit that indication is shared by the load that provided by the stress fiber coiling.The Woven fabric multiple tube does not provide enhancing and does not therefore provide this load to share characteristic.

[0013] therefore need improved fuel can, this fuel can is used in and comprises easy fission fuel in the nuclear-power reactor, and it provides improved safety and Performance Characteristics.

Summary of the invention

[0014] the invention provides a kind of multi-layered ceramic tube: described multi-layered ceramic tube comprises the internal layer of whole silit, and central core, this central core are to be carbonized the compound substance of the silicon carbide fibre that silicon substrate centers on and the skin of whole silit.Of the present invention one preferred aspect, the layer all form by stoichiometry β phase silicon carbide crystal.Of the present invention another preferred aspect, multi-layered ceramic tube can adopt fragment or as the overall length fuel rod, as the involucrum of fuel rod in reactor or the generating plant with can be grouped into the fuel assembly that comprises a plurality of ceramic pipes.Aspect present invention further optimization, each contains silit interval marking (spacer tab) or silk thread can be grouped into fuel assembly as the multi-layered ceramic tube of the integral part of its outside surface.Of the present invention still another preferred aspect, multi-layered ceramic tube can be used as heat interchanger.

[0015] from the following accompanying drawing of the explanation preferred embodiment of the invention, describe in detail and embodiment, other advantage of the present invention and feature are obvious.

The accompanying drawing summary

[0016] Fig. 1 is the schematic cross-section of multi-layered ceramic tube of the present invention.

[0017] Fig. 2 is the photo that is used to make the fiber preform of ceramic pipe of the present invention.

[0018] Fig. 3 is the photo of fiber preform that only has the winding part of the manufacturing process that part finishes, and the inside essence of preform structure is described thus.

[0019] Fig. 4 shows as radiation level, or the function of each atom of displacement (dpa), and the radiation intensity of composite material of silicon carbide is with respect to the figure of the ratio of the not radiation intensity of same compound material.

[0020] Fig. 5 is the perspective schematic view of typical pressurized water reactor (PWR) fuel assembly that has the array of involucrum fuel rod in assembly.

[0021] Fig. 6 indicative icon can be used for separating and supporting the machine configurations of the integrated spaced mark of the compound involucrum pipe of silit array.

[0022] Fig. 7 illustrates the purposes of multi-layered ceramic tube of the present invention as the secondary containment barrier of TRISO fuel pellet.

[0023] Fig. 8 compares for all kinds composite material of silicon carbide with conventional zircaloy, and temperature is to the figure of intensity data.

[0024] Fig. 9 A and 9B are the ceramic pipe photos of obtaining during manufacturing process.Fig. 9 A shows that two-layer at first and Fig. 9 B of ceramic pipe of the present invention shows the pipe of prior art.

[0025] Figure 10 indicative icon is used to measure the proving installation of ceramic pipe intensity of the present invention.

[0026] Figure 11 is the figure that shows the intensity measurements of ceramic pipe of the present invention.

[0027] Figure 12 compares the figure of whole carborundum tube strain-responsive with explanation with compound carborundum tube.

[0028] show can be by the viewgraph of cross-section of routine 15 * 15 fuel assemblies of silit or zirconium alloy cladding for Figure 13.

[0029] Figure 14 is the corrosion test result's of explanation silit sample of the present invention and pipe figure.

[0030] Figure 15 is exposed to the temperature that obtains during the coolant loss emergency conditions of the simulation figure to time data at ceramic pipe of the present invention.

Detailed description of the preferred embodiments

[0031] now in detail with reference to present preferred embodiment of the present invention, this embodiment and following embodiment one are used from and explain principle of the present invention.These embodiments are described with enough the level of details so that those skilled in the art can implement the present invention and understand and can adopt other embodiment and can carry out structure, chemistry and biological variation the and do not deviate from the spirit and scope of the present invention.

[0032] the invention provides a kind of multi-layered ceramic tube, this multi-layered ceramic tube has the ability of holding gas and liquid and do not have to leak under pressure, and simultaneously, adopts similar in appearance to the toughness mode of metal and other ceramic composite to show.Use this ceramic pipe to substitute traditional zircaloy involucrum that acts as a fuel, in nuclear reactor, to hold and to comprise uranium fuel and to allow effective heat transfer from the uranium fuel that comprises to external coolant.Ceramic pipe also can be used as the high-temperature heat-exchanging pipe in the commercial Application.Following description presents following characteristic of the present invention: allow single ceramic pipe to play these two kinds of functions and be presented on nuclear and industrial market in various application, wherein such feature can provide value.

A. structure and manufacturing

[0033] with reference now to Fig. 1, in a preferred embodiment of the invention, ceramic pipe 10 is made up of three silit (SiC) layer, with be suitable for use as present nuclear reactor, with the cladding nuclear fuels that is used for modified nuclear reactor of future generation, and be used for other purposes, as what in the portion C of describing in detail, further described.Three layers are by inner body layer 20, and Central Composite material layer 22 and protection outer 24 are formed, as shown in Figure 1.

[0034] inner body layer 20 is the high-purity beta phase chemistry metering silit that is formed by chemical vapor deposition (CVD) technology.Because this layer does not in fact have a hole, it is as the fission gas containment barrier, prevent during the normal running and the accident transient process during the release of radioactive fission gas.The use of CVD β phase SiC overcomes those the defective of existing product as describing in people such as Feinroth, they are made up of α phase sintering silit, comprise sintering aid such as boron or aluminium oxide, and between radiation era unacceptable swelling takes place easily.Referring to R.H.Jones, " Advanced Ceramic Composites for High Temperature FissionReactors ", Pacific Northwest Laboratory Report NERI-PNNL-14102 (in November, 2002).

[0035] Central Composite material layer 22 is made up of one or more layers of continuous β phase chemistry metering silicon carbide fibre, and this continuous β phase chemistry metering silicon carbide fibre closely is wound on the inner body pipe and by silicon carbide substrate and floods.Central Composite material layer 22 is prepared by following mode: at first assemble silicon carbide fibre and become tow, the coiling tow is to form preform and then preform to be adopted the silicon carbide substrate dipping.All material in the composite layer of dipping/matrix densification process transformation center becomes β phase SiC, and it guarantees the even swelling between radiation era and avoids delamination, the common fault mode of other compound substance between radiation era.

[0036] design fibrous structure especially with anti-machinery and heating power, and the selection and the control of fibre bundle tension force promotes the more even distribution of matrix material between tow and whole 20 and in tow during reeling from major accident.Tow is commercial and by in conjunction with the high-purity of 500-1600 root 8-14 micron diameter, the β phase, and silicon carbide fibre forms.Tow is wound up on the inner body pipe 20 in designing with the structure that suitable hoop and axial tensile strength and anti-internal pressure performance are provided, and as shown in Figure 2, its explanation is applicable to the various fibrous structures of making involucrum pipe of the present invention.

[0037] each adjacent tow is reeled and the previous overlapping radial structure globality anti-delamination to be provided and to increase of opposite direction tow coiling.This illustrates in Fig. 3, the tubular type preform that its declaratives is reeled, and this preform contains overlapping fibre bundle.Winding angle can change according to required intensity and repellence, and is such as is known to persons skilled in the art.Suitable physical strength adopts the winding angle that replaces between+45 degree and-45 are spent with respect to tubular axis to reach, and the winding angle of the layer that replaces between+52 degree and-52 degree randomly is equilibrated at the resistibility in hoop and the axial both direction.

[0038] bunch fiber is adopted interface SiC coating apply, comprise two sublayers-inner pyrolytic layer sometimes to provide necessary weak interface of loading duration slippage and outside SiC sublayer to protect carbon with anti-oxidant environment less than 1 micron thickness.These interface coatings can apply before reeling, perhaps, and after reeling but apply before the diafiltration at silicon carbide substrate.The existence of these interface coatings on the high strength chemistry metering fiber that is centered on by intensive matrix allows composite layer 22 to bear need bear the very high strain that accident situation needs in the nuclear reactor.

[0039] for example, people such as Besmann present following evidence: need the carbon interface coating of 0.17-0.26 micron to pull out and fine fault mode to guarantee the fiber in the SiC/SiC compound substance.Referring to people such as T.M.Besmann, " Vapor Phase Fabricat ion andProperties of Continuous Filament Ceramic Composites ", Science253:1104-1109 (on September 6th, 1991) is especially at Fig. 6.Similarly, the interface that enough weak and silicon carbide substrate on every side be provided less than the carbon contact bed of about 0.5 micron thickness applies load fiber down and pulls out and therefore allow involucrum pipe its uranium fuel containment ability of reservation under the hoop strain that surpasses 5% pipe diameter to be provided at.

[0040] then this " preform " adopted SiC matrix dipping in the rapid technology of multistep, the rapid technology of this multistep comprises matrix densification scheme such as chemical gaseous phase diafiltration (CVI), polymkeric substance diafiltration and pyrolysis (PIP), or both combinations.Impregnation technology produces and is showing the rigidity preform of β phase sediment around each fiber, uses PIP to produce to fill the space near the whole interface of compound substance sometimes.The final processing of densification matrix guarantees that all materials change into the β phase.

[0041] preferred diafiltration method is chemical gaseous phase diafiltration (CVI) technology.In this technology.The methyl trichlorosilane (MTS) that will mix with hydrogen is introduced the thermal reactor that is subjected to that comprises preform, typically under 900-1100 ℃ temperature, causes silit in the lip-deep deposition of thermal fiber.The pressure of pilot-gas, temperature and dilution are to maximize total deposition and to minimize remaining space.People such as Besmann have described five kinds of different classes of CVI technology that can be used for diafiltration.

[0042] CVI technology can be by other diafiltration method, as adopt SiC base polymer and β mutually the diafiltration of the slurry of SiC particle replenish, with further densification matrix.With organic polymer pyrolysis under various times and temperature, stay the SiC sediment of amorphous.Under the situation that is used for filling in the space in such technology, the annealing of carrying out subsequently becomes the β phase to transform silit, as growing with consistent with the minimum that guarantees matrix between radiation era.Require 1500-1700 ℃ annealing temperature to change mutually, and need to β full transformation mutually to guarantee acceptable performance under neutron irradiation to guarantee complete β.Referring to R.H.Jones, " Advanced Ceramic Compositesfor High Temperature Fission Reactors ", Pacific NorthwestLaboratory Report NERI-PNNL-14102 (in November, 2002).Selective annealing time and temperature be with the maximization densification with to matrix β conversion mutually, and do not cause the infringement to fiber self.

[0043] rigidity of inner body layer 20 more is higher than intermediate composite layer 22.Typically the Young modulus of SiC integral body is about the twice of SiC/SiC compound substance.Therefore, for guaranteeing to share circumference stress coequally in two load-bearing layers, composite layer 22 should be the same thick and preferably thicker with integral layer 20 at least.Preferably two pairs one thickness of composite material is to the ratio of integral thickness.This is required not ftracture during normal running in integral body guaranteeing, as need be to guarantee the reservation of fission gas.

[0044] the protection skin 24 of multilayer materials 10 is environmental protection shieldings, and design is to guarantee that reactor coolant (water, steam, gas, or liquid metals) is not because chemical erosion or corrosive effect and permanent damage composite layer 22.For some application and cooling medium, may not request this external protection 24.External protection 24 normally is made up of thin (less than 5 mils) silicon carbide layer, and this silicon carbide layer deposits on the previously described composite layer 22 by chemical gaseous phase depositing process.Be used for this silit of the 3rd layer and be high-purity beta phase chemistry metering silit and it can machining to thin surface smoothness, to for some application needs in the civilian nuclear reactor like that.

[0045] depend on required should with depend on available manufacturing environment, ceramic pipe 10 can adopt the various sizes manufacturing.For example,, need to surpass 12 feet ceramic pipe usually, reach at end seal to bear high pressure for using as can.Manufacturing with such long tube of sealing can be reached by following mode: the more short-movie section of at first making integral layer; engage by technology that confirms such as microwave and they to be bonded together and on whole length of tube, to form second composite layer and the 3rd protective seam then.Adopt this mode, keep the desired strength and the toughness of long tube in finished product, be reduced in any vulnerability of joint, it can cause the premature failure of finished product.

[0046] or, very long length C VD reactor can be used for making 12 feet long tubes and does not need and engages.After with easy fission fuel inlet tube, engage final silit end embolism (engaging or soldering) to tubing by ceramic joint technology such as microwave in fuel factory.Design is drawn joint to bear during operation and in machinery that applies during the accident and thermal force on fuel rod.One end of pipe can be sealed by phase Sihe end embolism before being transported to fuel factory during the pipe manufacturer.

B. physics and mechanical behavior

[0047] multi-layered ceramic tube is the mixed structure compound substance.Design that illustrates in this patent and processing scheme make multi-layered ceramic tube can have high initial resistance to cracking, rigidity, and final strength, the combination of excellent in resistance impact and thermal shock.The multilayer notion overcomes the many single restriction of bulk ceramics and fiber reinforced ceramic.For example, the inner body layer is than intermediate composite layer rigidity (elasticity is less) more, so use the same with the inner body layer at least thickly, and preferably help between these two load-bearing layers, to share circumference stress coequally than the Central Composite material layer of inner body bed thickness.Share circumference stress and help to prevent that cracking from occurring in integral body during normal running, therefore keep fission gas.

[0048] also be desirably in two bondabilities between the layer and share influential to load and that the center composite layer is suppressed the ability in crack is influential, this crack can occur during accident in integral layer.Although the fission gas reservation is not the requirement during design basis accident such as the coolant loss accident, the ability that the Central Composite material layer suppresses crack in the integral body has great importance during such accident, this is that such keeping is important safety and code requirement because it guarantees to cool off keeping of geometry.

[0049] compound ceramic pipe sample of the present invention is carried out mechanical test, as described in the embodiment 4.The compound ceramic pipe is the ceramic pipe of the present invention that does not also contain the external protection of manufacturing, and promptly multiple tube contains previous described inner body and Central Composite material layer.As described in example 4 above, the Central Composite material layer continue to keep 9% its basic structure globality of leaving overall strain, and its indication ceramic pipe can survive accident and not explosion and discharge fuel.In addition, silit has the swelling accepted up to each atom of 100 displacements (dpa) when raying, and it equals to surpass commercial PWR device operation in 30 years.Referring to R.H.Jones, " Advanced CeramicComposites for High Tempera ture Fission Reactors ", PacificNorthwest Laboratory Report NERI-PNNL-14102 (in November, 2002).Equally, when composite material of silicon carbide adopted recent available stoichiometric fibers to make, they kept their intensity to very high radiation level, show as Fig. 4.

[0050] for example, test result combines with the data of Fig. 4, and the indication ceramic pipe can bear the power up to the reactivity insertion accident of very high dpa level, equals 100,000 megawatt day per metric ton uranium burnups, or higher.Equally, test result also indicates ceramic pipe can survive the design considerations reactivity accident, and expanding in the inside of the anti-involucrum of uranium fuel particle that wherein comprises, causes very high strain.The accident of the ceramic pipe ability of escaping by luck is a remarkable advantage with respect to conventional zirconium alloy cladding, and this is because its allows ceramic pipe to use the longer time and is more using under the high burnup.

[0051] conventional zirconium alloy cladding is desirably in only 1-2% strain and ftractures in the fragility mode afterwards when complete raying.To high-octane long exposure (about 5 years) afterwards, the conventional zircaloy and the metal that are used for fuel can become fragile, and it produces safety problem during high temperature and/or high thermal force situation, and this load situation can occur during plausible accident situation.For the restriction embrittlement with avoid the explosion of involucrum, uranium fuel for zirconium alloy cladding, present NuclearRegulatory Commission (NRC) practice is the fuel burn-up to 62 in the water-cooled civilian nuclear reactor of restriction operation, the uranium (mwd/t) that 000 megawatt day per metric ton comprises.The analysis foundation of this restriction of the fuel of zirconium alloy cladding presents in following document: NUREG/CR-6703, " Environmental Effects of Extending Fuel Burnup Above 60GWD/MTU ", (January calendar year 2001), with Westinghouse Report WCAP-15063-P-A, revised edition 1, with Errata, " Westinghouse Improved Performance Analysisand Design Model (PAD 4.0) " (in July, 2000).

[0052] yet, expect that multi-layered ceramic tube of the present invention keeps its toughness, even the very long Energy extraction cycle (＞10 years) afterwards, therefore allow the Energy extraction of bigger quantity, improve the radioactive waste quantity that economy and the source utilizes and per unit produces electricity produce.Adopt this new the present invention, the Energy extraction speed that surpasses 100,000 mwd/t can be actual.Such high-energy extraction rate reduces the used quantity of fuel of the energy of every kilowatt hour generation substantially, therefore reduces the burden for the National Geologic repository of used fuel.

[0053] test of carrying out shown in embodiment 7 is indicated when the temperature that is exposed to above 1200 ℃, and the composite material of silicon carbide that is used for ceramic pipe of the present invention keeps their intensity and do not experience significant corrosion or weight change.These test results indicate ceramic pipe of the present invention can survive design considerations coolant loss accident, reach and surpass 15 minutes times even temperature surpasses 1200 ℃, and do not discharge the uranium fragment that comprises to cooling medium with there is not the loss of ceramic pipe structural integrity.Following test of expectation shows and compares in these preliminary tests, for the longer time in addition the higher temperature tolerance.

[0054] but when being exposed to high temperature the raising intensity of ceramic pipe allow the allowable temperature on involucrum surface to be increased to 900  (482 ℃) and more up to lacking the duration, as during loss-of-flow accident, taking place, and do not have the loss of physical strength.In other words, can allow to deviate from ucleate boiling (DNB), sometimes this deviate from by for the NRC standard of metal casing practice forbid.Referring to NUREG/CR-6703, " Environmental Effects of Extending Fuel BurnupAbove 60 GWD/MTU " (January calendar year 2001), with Westinghouse ReportWCAP-15063-P-A, revised edition 1, with Errata, " Westinghouse ImprovedPerformance Analysis and Design Model (PAD 4.0) " (in July, 2000).Allow the more high heat-flux during DNB can allow normal running, it allows to surpass according to subsidy adopts the now possible power through permitting civilian reactor of metal casing to upgrade.This allows the nuclear device owner to produce under higher rate from existing nuclear power plant successively.

[0055] under the temperature higher than typical metal pipe, ceramic pipe intensity at high temperature keep also allowing its carry out following both: gas reservation function and adopt the intensity of the ductile behavior function that fuel can requires.Referring to the test result among the embodiment 1.Compare with the fuel of present zirconium alloy cladding, this intensity also allows ceramic pipe of the present invention before requiring to substitute, and when as fuel can, operates the longer time and has bigger energy production.

[0056] another advantage of ceramic pipe is that silit is stone material, with not owing to wearing away with hard fragment or contacting of grid spring material.At present, in the fuel assembly of conventional zirconium alloy cladding, exist little, though acceptable failure rate mainly is because from the involucrum fault of fragment or grid wearing and tearing.The basic reason of fault is the soft relatively essence of metal casing like this.The hardness of ceramic pipe is favourable, and this is because failure rate is lower substantially, causes device cut-off phase of reducing and lower fuel alternative cost.Other benefit is for storing, and transports and final the processing after reactor takes out, and compares involucrum with present zirconium alloy cladding and has bigger residual intensity and durability.During storing and handle, this prolongation at used nuclear fuel provides safety benefits.

C. the application of multi-layered ceramic tube

Pressurized water reactor (PWR) purposes

[0057] Fig. 5 is illustrated in typical pressurized water reactor (PWR) fuel assembly that contains the involucrum fuel rod array in the assembly.Have about 67 PWR in operation in the U.S. at present, and some have 15 * 15 arrays shown in Figure 5 and other and have and use the bigger array of minor diameter fuel rod.Single fuel rod can be by conventional zircaloy, or multi-layered ceramic tube involucrum of the present invention.

[0058] if being used for the external diameter of the conventional zirconium alloy cladding pipe of 15 * 15 fuel rod arrays is about 0.422 inch and former excellent involucrum pipe of alternative conventional fuel that is designed for, ceramic pipe external diameter of the present invention should be about 0.422.Having identical external diameter allows ceramic pipe of the present invention directly to substitute conventional pipe at 15 * 15 fuel rod arrays that typically are used for the PWR fuel assembly.External diameter is that about 0.422 inch ceramic pipe contains the thick whole internal layer of the 0..010 inch of having an appointment, about 0.013 inch thick Central Composite material layer and about 0.002 inch thick protection skin.

The boiling water reactor purposes

[0059] using second type of reactor at present is boiling water reactor (BWR).There are 35 such reactors to be in commercial the use in the U.S..In use there are several different fuel elements designs once more at this.The example of general a kind of design is 9 * 9 designs.Conventional zirconium alloy cladding in present 9 * 9 BWR design has 0.424 inch external diameter and 0.030 inch wall thickness.Substitutes ceramic involucrum and have approximately identical external diameter and wall thickness, and the inner body layer is about 0.012 inch that the Central Composite material layer is 0.014 inch and outerly is about 0.004 inch.This provides the direct of 9 * 9 BWR design of zirconium alloy cladding to substitute.

Use the fuel rod support system of interval marking

[0060] the unique design feature can be introduced single fuel rod, it allows to have stable and long-term support of " array " (being called " fuel assembly ") of the ceramic involucrum fuel rod of external dimensions, and this external dimensions allows directly substituting of existing metal casing fuel assembly in the present commercial reactor.This design feature be along the involucrum pipe several axially and the integrated spaced mark arranged of radial position, or silk thread at interval, it remains on by the heat of the cooling medium that flows and extracts spacing between the fuel rod of requirement.Because silit is stone material, the possibility of interval marking or silk thread minimum wear fault is used to support fuel rod such wear-out failure can take place if having the conventional metals grid of spring.From the integrated spaced mark of metal preparation as the fuel rod support feature some existing reactors, for example be used for Canadian CANDU commercial reactor, with at Department of Energy ' s Hanford, in the Fast Flux Test Facility reactor that Washington, facility build and operate.Typical integrated spaced mark array 30 on silit multiple tube 10 outside surfaces that Fig. 6 explanation requires in the present invention.

[0061] the third option that supports the fuel element of silit involucrum in the fuel assembly array is the metallic grid that adopts the same type of the fuel rod that is used to support zirconium alloy cladding at present.The example of grid is seen Fig. 5 like this.Because it is firmer than the fuel rod of present zirconium alloy cladding that the fuel rod of silit involucrum can be thought of as, the distance that can increase between the supportive grid is avoided the vibration of flow-induction simultaneously, so reduces the grid number of each fuel assembly requirement.This causes lower cost, and the anti-flowability that the parasitic neutron of reduction absorbs and reduces all allows improved fuel assembly performance.

The segmentation rod and refuel during layout again

[0062] as before discussing in the part A of describing in detail, ceramic pipe of the present invention can the burst manufacturing, with this sheet soldering or combine in addition, maybe can be fabricated to single 12 feet unit.The alternative method of making 12 feet worker's fuel rods is to adopt several shorter fuel rod fragments, and this fragment can adopt mechanical connection, as is threaded, and combines at the scene or in fuel factory.

[0063] be used to allow the test fuel element deliver to laboratory inspection although this technology is used for commercial water reactor sometimes, it also is not used in commercial fuel.Reason be other end embolism and axially fission gas supercharging part cause unacceptable axial peaking factor, cause the remarkable loss of generating surface in the reactor core and cause the reduction of volume of fuel, it causes the unacceptable increase of uranium enrichment level.

[0064] if in following water reactor, the silit involucrum is replaced zirconium alloy cladding, relaxes these reasons, therefore allow to use the segmentation rod.For example and since the silit involucrum than zircaloy firm and not since the external pressure creep to fuel particle, intrinsic free gas volume may be enough to comprise fission gas and not have axial supercharging part in the fuel element of silit involucrum.The water reactor fuel element that is used for present CANDU fuel comes down to the segmentation rod, does not comprise axial supercharging part and has acceptable axial peaking factor.According to this analysis, use with this silit involucrum that proposes can allow to use the segmentation fuel rod in commercial PWR and BWR, therefore be provided at and arrange possible the advantage of each fuel fragment again during refueling, so allow the basic reduction of peak value to evenly heat power and peak value to average burn-up.

[0065] use of segmentation rod also allows directly to re-use the single split rod in the CANDU reactor, so-called DUPIC notion, and do not require and separate involucrum and drying cycles by the LWR fuel rod of previous DUPIC concept requirement.Present DUPIC economy is favourable, mainly is owing to need separate involucrum and make used nuclear uranium fuel again.Referring to people such as H.Choi, " Economic Analysis of Direct Use of Spent Pressurized WaterReactor Fuelin CANDU Reactors ", Nuclear Technology 134 (2) (May calendar year 2001).The PWR reactor fuel of segmentation silit involucrum is eliminated this very expensive technology and made DUPIC circulate in commercial is spendable.

Modified supercritical water reaction heap purposes

[0066] U.S. and other national design improvement type nuclear reactor, some of them adopt the supercritical water cooling.Many coal-fired power plants have adopted the supercritical water operation.The design of modified supercritical water reaction heap is by one of six modified notions of Generation IV International Forum research.Ceramic pipe of the present invention is as the fuel can of these reactors.

[0067] in a variant of this modified reactor, being 300 ℃ with outlet temperature is that 33% present PWR compares with unit efficiency, and coolant outlet temperature is that 500 ℃ and unit efficiency are 44%.Zircaloy can not be used as fuel can under these temperature, this is because they lack suitable physical strength.Steel superalloy and oxide dispersed steel are thought of as possible alternative metals involucrum, but these materials are abilities that parasitic neutron absorber and disturbance reponse heap reach high burnup.They also may experience stress corrosion crack.The research of silit involucrum is the fuel canning material of USDOE's supercritical water reaction heap design.Machinery and thermal behavior equal or substitute cladding materials and nuclearity can be better than available substitute substantially.

[0068] conceptual design that is used for the silit fuel can of supercritical water reaction heap is studied by Idaho National Laboratory.The configuration of 21 * 21 fuel assemblies is used in this design, and the involucrum external diameter is that 0.48 inch and wall thickness are the .056 inch.Compare for identical uranium fuel load with the design of using the oxide dispersed steel involucrum, adopt this design of silit involucrum can reach big 32% burnup, this is to compare few substantially parasitic neutron absorptive character with oxide dispersed steel because it has.Referring to J.W.Sterbentz, " Neutronic Evaluationof 21.times.21 Supercritical Water Reactor Fuel Assembly Designwith Water Rods and SiC Clad/Duct Materials ", Idaho NationalEngineering Laboratory report INEEL/EXT-04-02096 (in January, 2004).In addition, 31,000 mwd/t that design with the ladle shell compare, and the burnup of silit design is 41,000 mwd/t.

Application to modified gas reaction heap

[0069] several Generation IV modified reactor concepts use very high-temperature gas as cooling medium to extract heat and to allow that heat to change into electricity or change into hydrogen.In some cases, these modified reactor designs are used similar in appearance to those " rod " kind of fuel elements that are used for water reactor.Under these circumstances, fast gas reactor for example, ceramic pipe of the present invention allows improved performance.For example, some researchists that carry out the physical analysis of many gas with various rapid reactions heap primary design obtain as drawing a conclusion: " the SiC[involucrum] aspect neutron, be the most attractive material.Yet the strength of materials requires to limit its use." people such as E.A.Hoffman, " Physicss tudies of Preliminary Gas CooledReactor Designs ", Global 2003 Nuclear Fuel Cycle Conference, ANS (in November, 2003).Disclosed multi-layered ceramic tube overcomes this intensity restriction and allows the neutron advantage that following deviser utilizes to be provided by silit among the present invention.

The reactor of liquid metals cooling

[0070] several modified reactors according to Generation IV International Program exploitation use the liquid metals cooling medium, comprise plumbous and lead-bismuth eutectic.Consider 700-800 ℃ outlet temperature.Disclosed multilayer silit fuel can be used for this application and has those the similar advantage of discussing for gas and water coolant similar in appearance to above among the present invention.The literature review that consideration is used for the various materials of plumbous cooled reactor involucrum draws as drawing a conclusion: the silit multiple tube of disclosed type is the preferably selection of involucrum in this type reactor among the present invention.Referring to people such as R.G.Ballinger, " An Overview of Corrosion Issuesfor the Design and Operation of High Temperature Lead andLead-Bismuth Cooled Feactor Systems ", Nuclear Technology147 (3): 418-435 (in November, 2004).

The secondary shielding that is used for HTGR TRISO fuel pellet

[0071] Fig. 7 illustrates the Another application of multi-layered ceramic tube of the present invention, promptly as the secondary containment barrier of TRISO fuel pellet in the prismatic high temperature gas reactor (HTGR), HTGR is thought of as at Idaho NationalLaboratory for modified Generation IV reactor by Ministry of Energy and constructs.HTGR typically uses the fuel particle of the special exploitation that is called " TRISO " particle, and this particle is by forming as the lower part: spherical inner core and a few micron thickness coat of silicon carbide of the uranium enriched fuel that is covered by the porous carbon cushion.The carbon cushion holds the swelling of fuel kernel and promotes to be used for the voidage of gas fission product, and coat of silicon carbide is as the mechanical masking of gas fission product.

[0072] TRISO fuel particle is compacted into the cylinder that is called pellet by graphite matrix sometimes, and it inserts graphite block.Yet under the situation that very the high-temperature gas reaction is piled, for example Outlet Gas Temperature is those of 1000 ℃, and the thin SiC coating on the particle may be not enough to guarantee that fission gas keeps; Can require secondary shielding to discharge to guarantee zero of safe operation and fission product.

[0073] the fuel assembly fragment that shows on Fig. 7 left side 100 is made up of graphite block, bore cylindrical hole so that coolant channel to be provided by this graphite block, with the opening that fuel pellet is provided, it normally is made up of very little (less than the 1mm diameter) fuel particle, and this fuel particle compresses graphite fuel pellet into about 0.5 inch diameter by silicon carbide coating.The fragment that shows on Fig. 7 the right shows the secondary shielding that centers on the graphite fuel pellet and be used as secondary fission gas shielding, to comprise any fission gas that discharges from TRISO fuel particle.Secondary shielding is made up of compound (two-layer variant) of the present invention ceramic pipe 10, and it contains inner body layer 20 and Central Composite material layer 22, and the silit end cap 32 that centers on fuel 40.

[0074] the multilayer SiC pipe that provides among the present invention provides very reliable for this application, minimally-invasive, secondary fission gas shielding.TRISO fuel particle is compressed into graphite matrix pellet (having half inch external diameter), as in this HTGR design and then these pellets are encapsulated into multi-layered ceramic tube of the present invention.Then these pipes are inserted prismatic graphite block, it forms the essential structure piece of pyroreaction reactor core, as shown in Figure 7.

The SiC heat interchanger

[0075] the common application of silicon carbide ceramic in commercial Application is the internal heat exchange tubes that is designed in the shell-and-tube heat exchanger of high temperature application.Sometimes such heat interchanger adopts fluid to use, and this fluid at high temperature is a high corrosion to metal, but compatible with silit.The shortcoming of this type heat interchanger when adopting whole carborundum tube to prepare, is its fault behavior; Whole silit breaks down in the fragility mode.Overcome the alternative silicon carbide fibre-silicon carbide substrate complex pipe that is to use of this unfavorable behavior, it keeps the fine fault mode of metal.Yet these pipes are air inclusion or liquid under high pressure.Yet the use of ceramic pipe of the present invention overcomes these two shortcomings and is provided in the industrial use possibility of using silicon carbide heat exchanger, and this purposes can not be by all integral tube, or all complex pipes satisfy.

[0076] according to the instruction that comprises at this, in the limit of power that is applied in those skilled in the art of instruction of the present invention to particular problem or environment.The embodiment of product of the present invention and method occurs in following embodiment.

The ionization meter of embodiment 1-silicon carbide ceramics

[0077] Fig. 8 compares with conventional zircaloy, similar in appearance to the composite layer of this ceramic pipe, for the summary of the temperature of all kinds composite material of silicon carbide ground intensity data.Data obtain from open source literature.The abbreviation that is used for Fig. 8 is explained in following table.

Abbreviation	Meaning	The source
			SiC-cg	Adopt the SiC/SiC compound substance of cg-Nicalon fiber	S.J.Zinkle and LL. Snead of ORNL
SiC-hi-nic	Adopt SiC/SiC compound substance mutually between Hi-Nicalon fiber and PIP matrix and BN	H.Ichikawa of Nippon Carbon
			SiC-Type-s	Adopt SiC/SiC compound substance mutually between Hi-Nicalon type-S fiber and PIP matrix and BN	H.Ichikawa of Nippon Carbon
SiC-Tyranno	Adopt SiC/SiC compound substance mutually between Tyranno-SA fiber and CVI matrix and PyC	T.Nozawa and L.L. Snead of ORNL
			Zirc-4 Billone	Framatome hangs down tin zircaloy-4	M.C.Billone of ANL
Zirc-2	Zircaloy-2	E.Lahoda

[0078] as illustrated in fig. 8, zircaloy is all its intensity of loss under about 600 ℃ temperature in fact.Owing to this reason, the operation that limits present water reactor makes avoids deviating from ucleate boiling (DNB) during the operation transient process, therefore prevent the fault of involucrum during such transient process, and it can cause the localization clad temperature above 800 ℃.As shown in Figure 8, the silit involucrum keeps its intensity of great majority under 800 ℃ and above temperature, therefore allows DNB to occur during the operation transient process and does not cause localization involucrum fault.This feature can allow the basic increase of power grade and the more large economy of present commercial nuclear reactor.

Embodiment 2-makes ceramic pipe

[0079] illustration two-layer ceramic pipe of the present invention is formed by following process.At first, chemical vapor deposition (CVD) technology is used for forming according to technology known in the art the inner body layer of high-purity beta phase chemistry metering silit.Secondly, adopt various coiling patterns and use various winding angles on the inner body pipe, closely to reel by the high-purity of 500-1600 root 8-14 micron diameter, the β phase, the commercially available fibre bundle that silicon carbide fibre forms is shown in Fig. 2 and 3, with preparation " preform ".

[0080] then these " preforms " are adopted thin RESEARCH OF PYROCARBON contact bed to apply, adopt the SiC matrix to use the isothermal effect of Fluid Pulsation technology dipping of chemical gaseous phase diafiltration then, this technology is described as " type V " in following document: people such as T.M.Besmann, " Vapor PhaseFabrication and Properties of Continuous Filament CeramicComposites ", Science 253:1104-1109 (on September 6th, 1991).The methyl trichlorosilane (MTS) that will mix with hydrogen is introduced the thermal reactor that is subjected to that comprises preform, typically under 900-1100 ℃ temperature, causes silit in the lip-deep deposition of thermal fiber.The pressure of pilot-gas, temperature and dilution are to maximize total deposition and to minimize remaining space.

[0081] Fig. 9 A illustrates the pipe of method manufacturing thus, and described pipe contains the uniqueness of being produced by the chemical vapor infiltration filtering technology " hands over more " fibrous structure and matrix.The inner body layer is a thin-walled, about 0.030 inch.The thickness of multiple tube is that about 0.040 inch and external diameter are about 0.435 inch.Normally, use CVD technology well known by persons skilled in the art, outer these pipes that are deposited to of protection silit are gone up to shield as environment.This deposition normally is a final step of manufacturing process.

Embodiment 3-makes the pipe of prior art

[0082] Fig. 9 B explanation is according to two carborundum tubes of the method manufacturing of philtrums such as Feinroth description.Forming thick relatively integral layer (about 0.125 inch) afterwards, will manage and adopt silit to cover.Left side pipe employing hoop coiling silicon carbide fibre is covered and the pipe employing on the right is weaved or the covering of envelope curve silicon carbide fibre.Further details provides in following document: people such as H.Feinroth, " Progress in Developing an Impermeable; HighTemperature Ceramic Composite for Advanced Reactor CladApplication ", American Nuclear Society Proceedings-ICAPPconference (in June, 2002).Use the method for describing among the embodiment 2, preform is adopted SiC matrix dipping.

Embodiment 4-intensity and strain testing

[0083] when at room temperature experiencing internal pressure, use equipment illustrated in fig. 10, at the stress-strain behavior of the multiple tube of in Oak Ridge National Laboratory-HighTemperature Materials Laboratory test implementation example 2, making during in January, 2005.As shown in figure 10, basic equipment is made up of support column 50 and plunger 52.With sample hose 10 upwards or " on the end " on support column 50, places, and polyurethane embolism 54 made in sample hose 10 inner outfits between embolism external diameter and sample hose internal diameter, have primary clearance 56.The depression that embolism 54 is equipped with on the support column 50.Top and the downward power of using plunger 52 to apply force to polyurethane embolism 54 change into outside (hoop) power that is applied to sample hose 10 internal diameters.

[0084] result of these tests presents in Figure 11 and 12.Figure 11 presents the hoop intensity measurements of typical multiple tube of the present invention.The integral layer of the multiple tube of test is than compound substance bed thickness, and therefore it does not receive any enhancing from composite layer before breaking down.The left half (0-2 on the X-axis) of mapping curve is presented at the pipe integral part when being kept perfectly, and load is to the rising in the strain.When whole internal layer comprised from fission gas that the uranium fuel that comprises produces, this part of curve was presented on the condition of arranging during the reactor normal running.As shown, whole about 37, break down under the stress level of 000psi.At 0.422 inch external diameter, 30 mil gross thickness, in the pipe of the whole internal layer of 15 mils, this proof stress is enough to be retained to many 4000psi internal pressure, and it is included in reactor and prolongs the fission gas that operating period produces.

[0085] right half of curve (2-9 on the X-axis) illustrates even after integral body broke down, it can occur during major accident among Figure 11, and outside composite layer hoop intensity is greater than 13,000psi, the total hoop strain up to 9%.Ceramic pipe of the present invention allows very high strain and does not have the ability of primary circle tubular construction to be unique to the present invention who requires and to guarantee that the fuel that comprises is not released into cooling medium, even under the situation of the major accident that causes very high cladding strain.

[0086] Figure 12 compares the initial strain response of multiple tube of the present invention and the initial strain response of integral tube, and these two pipes are by equipment load illustrated in fig. 10.Although the whole internal layer of integral tube and multiple tube is accurately identical, owing to the enhancing that is provided by composite layer, multiple tube shows higher Young modulus.

The analysis of parasitic neutron absorption of embodiment 5-and burnup ability

[0087] carry out comparing with the fuel assembly of conventional 15 * 15 zirconium alloy claddings, the contrast that the parasitic neutron of the fuel assembly of 15 * 15 silit involucrums of the present invention (" SiC fuel assembly ") absorbs is calculated.Two fuel assemblies comprise the fuel rod of 225 involucrums, and as shown in figure 13, the active length of each is that 366cm and external diameter are 0.422 inch.It is 0.0245 inch (24.5 mil) with thickness that the internal diameter of zircaloy fuel assembly involucrum is 0.3734 inch.SiC fuel assembly involucrum is overall 0.0250 inch thick (25 mil) and comprise two layers, and internal diameter is that 0.372 inch and external diameter are the composite layer that 0.400 inch integral layer and external diameter are 0.422 inch.Calculating is for the number of densities of the atom species of each assembly, their neutron xsect, and macro cross-section and the results are shown in following table.

	The zircaloy fuel assembly	The SiC fuel assembly
			Average number density, n (atom/cm 3)	Zr 4.035×10 21 Nb 2.718×10 19 Sn 3.106×10 19	Si 3.890×10 21C 3.890×10 21
The neutron xsect, σ a(target)	Zr 0.185 Nb 1.150 Sn 0.610	Si 0.171 C 0.0034
			Average macro cross-section, ∑ a(cm -1)	0.0007967	0.0006784

[0088] these results indication is compared with the fuel assembly of zirconium alloy cladding, and the parasitic neutron of the fuel assembly of silit involucrum absorbs low about 15%, as being measured by the xsect that reduces.This reduction that parasitic neutron absorbs causes more high burnup ability and the Geng Gao for the assembly of SiC involucrum, and more effective fuel utilization is for every kind of identical uranium enrichment of situation supposition.For example, from 60,000 mwd/t to 70, the burnup increase of 000 mwd/t is possible and not from any increase of the uranium enrichment of present 5% uranium 235 enriched level to present LWR.The higher level that adopts uranium 235 to concentrate is possible to the higher increase of the burnup of 100,000 mwd/t and Geng Gao.

Embodiment 6-abolishes (rescission)/corrosion test

[0089] Figure 14 is the figure that presents the corrosion test result under the simulated conditions that silit sample and Guan Zai represent typical BWR coolant conditions.With the modified zirconium alloy pipe of standard, many silit test samples and pipe are exposed under the normal running temperature of about 680  (360 ℃) the BWR cooling medium in the testing high voltage still.After test, sample is weighed and weight gain or loss are changed into abolishment, or owing to expose the quantity (load) of the basic material of loss.

[0090] data are rendered as material unaccounted-for (MUF) (abolishment) to exposure duration.Figure also comprises the similar data about conventional zircaloy.Under the situation of these alloys, because the zirconium burning becomes oxide, exposure causes weight to increase.Yet because this is important according to the intensity of remaining structure, the data conversion among this figure becomes effective material unaccounted-for (MUF) (or abolishment).Figure 14 illustrate the silit sample between exposure period under the speed lower than zircaloy the loss structure material, it is to be of value in the commercial reactor prolonging the duration operation and being of value in the use that prolongs bunkering and another advantageous property of more durable fission product containment during the processing cycle.

[0091] all sic pipe is showed the abolishment of lacking than zircaloy, and some reach 100 times.If by more prolonging, more the long duration corrosion test is confirmed, the corrosion-resistant and oxidation susceptibility of this increase allows compound involucrum to guarantee to stay it under normal running temperature durability and fission product containment function are far above 5 years that can reach from zircaloy, with 62,000 mwd/t.

The coolant loss accident of embodiment 7-simulation

[0092] temperature of the test carried out at Argonne National Laboratory in September, 2004 of Figure 15 is to time diagram, wherein carborundum tube is exposed to typical coolant loss accident in the PWR reactor, is about to visitor's and under the temperature of 2200  (1204 ℃), exposes 15 minutes.This type accident is the design basis accident of commercial nuclear reactor and normally causes at least 17% zirconium alloy cladding oxidation in less than 7 minute.Argonne report carborundum tube exposes test period at this does not have measurable thickness loss.Referring to Electronic Message fromMichael Billone, Argonne National Laboratory, Denwood Ross, Gamma Engineering, the weight measurement (on November 2nd, 2004) of report " SiC steam oxidation test #2 (SiC steam oxidationtest#2) ".This embodiment illustrates that multi-layered ceramic tube of the present invention can survive the design considerations coolant loss accident that surpasses 1200 ℃ and reach and surpass 15 minutes time, and does not discharge the uranium fragment that comprises to cooling medium with there is not the loss of tubular construction globality.

[0093] provides the above disclosure of the preferred embodiment of the invention for the purpose of illustration and description.It is not wished is exhaustive or limits the invention to disclosed precise forms.According to above disclosure, many changes and improvements of embodiment described herein are obvious to those skilled in the art.Scope of the present invention only limits by so far appended claim with by their coordinator.

[0094] in addition, in describing representative embodiment of the present invention, instructions can present method of the present invention and/or technology is specific sequence of steps.Yet, not relying on degree to method or technology in the particular order of steps of this explanation, method or technology should be not limited to described particular order of steps.As it will be appreciated by those skilled in the art that other sequence of steps can be possible.Therefore, the particular order of steps that illustrates in the instructions should be not interpreted as the restriction to claim.In addition, the claim that relates to method of the present invention and/or technology should be not limited to that their steps can recognize easily with the carrying out of write order and those skilled in the art that order can change and still within the spirit and scope of the present invention.

Claims (20)

1. multi-layered ceramic tube comprises:

The internal layer of whole silit;

Central core, this central core are the compound substances that is carbonized the silicon carbide fibre that silicon substrate centers on; With

The skin of whole silit.

2. the multi-layered ceramic tube of claim 1, as cladding nuclear fuels and fuel containment container, internal layer wherein, central core and skin all are made up of stoichiometry β phase silicon carbide crystal, the anti-infringement that is caused by neutron irradiation of this crystal.

3. the multi-layered ceramic tube of claim 2, wherein the silicon carbide fibre of central core be continuous and be configured as tow and wherein this tow around internal layer, reel separately and make tow that each is adjacent and previous opposite direction tow overlapping.

4. the multi-layered ceramic tube of claim 2, wherein internal layer can keep its leakage tightness, even during the nuclear fuel that comprises in by whole nuclear fuel cycle when experience fission gas pressure that produce, that surpass at least 100 m. gigawatt (GW)s-every kilogram of uranium that comprises in sky.

5. the multi-layered ceramic tube of claim 2, wherein continuous carbofrax fibre is applied by the carbon-coating less than about 0.5 micron thickness, and this carbon-coating provides and the interface of silicon carbide substrate on every side.

6. the multi-layered ceramic tube of claim 2, wherein ceramic pipe can keep its structure not discharge their abilities to cooling medium with comprising inner uranium fuel pellet, even during the design considerations reactivity insertion accident, with in addition after the neutron irradiation of the energy generation that receive to surpass 100,000 megawatts-uranium fuel that sky per metric ton comprises.

7. the multi-layered ceramic tube of claim 2, wherein said pipe is surpassing gas tightness, mechanical property and the structural integrity that keeps it under 800 ℃ the coolant temperature, therefore the nuclear device operation transient process that allows the involucrum pipe to survive to relate to film boiling, but and there is not an infringement of continued operation in the limited reactions heap.

8. the multi-layered ceramic tube of claim 2, wherein said pipe survive the design considerations coolant loss accident that surpasses 1200 ℃ and surpass 15 minutes time, and the fragment that does not discharge the uranium that comprises is to cooling medium with there is not the loss of tubular construction globality.

9. the multi-layered ceramic tube of claim 2, wherein said pipe after the energy that exhausts it produces ability after the reactor discharge, during reactor is stored cycle stretch-out, during being transported to repository, therefore containment barrier with continuing during permanent several centuries of handling in such repository to provide cracking resistance sell of one's property thing to discharge reduces the possibility that radioactive isotope discharges from the geology storage facilities.

10. the multi-layered ceramic tube of claim 2, wherein said pipe can with the encapsulation uranium dioxide, fission product and actinide directly are dissolved in melten glass together, to produce fused glass block, described fused glass block self is compared with used fuel, has the anti-dissolubility to water-bearing media of big at least one order of magnitude.

11. the assembly of forming by a plurality of fuel tubes, wherein each fuel tube is the ceramic pipe of claim 2, wherein fuel tube has low at least 15% parasitic heat neutron absorption xsect, with therefore can adopt 5% identical uranium 235 enrichment to reach at least 70, the fuel burn-up of 0000mwd/t, the present zirconium alloy cladding fuel of described 5% uranium 235 enrichment restriction is to about 60,000mwd/t.

12. be used for the nuclear fuel rod carrier system of the fuel element of silit involucrum, comprise a plurality of silit fuel tubes, wherein each involucrum pipe contains silit interval marking or the silk thread integral part as the involucrum tube outer surface, directly contacts with interval marking on the single involucrum pipe wherein or silk thread and adjacent involucrum pipe to make each involucrum pipe and other involucrum pipe separate and the vibration of anti-flow-induction.

13. the assembly of forming by a plurality of ceramic pipes of claim 2, the axial cell structure that employing is lacked substantially than present fuel assembly design, but keep overall resistibility, as in the conventional zirconium alloy cladding fuel assembly with more axially cell structure to the vibration of crooked and flow-induction.

14. the fuel fragment of sealing comprises the ceramic pipe of claim 2 and the uranium fuel element that comprises in ceramic pipe, wherein each fuel fragment be about 18-30 inch long and wherein the fuel fragment have and be threaded.

15. segmentation overall length nuclear fuel rod comprises a plurality of fuel fragments of claim 14, described fuel fragment is combined by being threaded to form 12 feet nuclear fuel rods in their end.

16. the segmentation overall length nuclear fuel rod of claim 14, wherein this fuel fragment can be considered after so much energy release of permission by nuclear reactivity in receiving light-water reactor, in the use of light-water reactor take apart each other in the fuel tank, be configured to shorter section or fuel cluster again with pressure cast heavy water reactor compatibility, be transported to that reactor in the protection bucket and and then insert that reactor and be used for Continuous Energy production.

17. the assembly of forming by a plurality of fuel tubes, wherein each fuel tube is the ceramic pipe of claim 2, wherein fuel tube has low at least 30% parasitic heat neutron absorption xsect, can force rate can adopt high by 30% that modified ladle package reaches with therefore fuel burn-up, this ladle package considers to be used for modified supercritical water reaction heap now.

18. the multi-layered ceramic tube of claim 2, further being included in the rapid reaction heap fuel form that comprises in the ceramic pipe and wherein such rapid reaction heap fuel form is plutonium or high enriched uranium oxide, nitride or carbonide.

19. the multi-layered ceramic tube of claim 2 further is included in the tight part of TRISO nuclear fuel that comprises in the ceramic pipe.

20. comprise the heat interchanger of the ceramic pipe of a plurality of claims 1, wherein the end of ceramic pipe between two flat circular plate or tube sheet installed and engaged, therefore the major diameter silicon carbide compound cylinder around it joins to successively constitutes shell-and-tube heat exchanger.

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