The method of preparation of materials, predominantly non-metallic, for use in neutron fields
(57) Abstract:The invention relates to methods of processing materials intended for use in the core of nuclear reactors. The preparation of predominantly non-metallic materials for use in neutron fields provide shock-wave effects generated by explosives. The amplitude of the pressure P when the effect is selected in the range: 1 HPa < P 100 HPa. The invention relates to a method of processing materials intended for use in the core of nuclear reactors.When the materials in the core of nuclear reactors characteristic is the increase in dimensions of the parts, i.e., the decrease of the density of the materials. The most significant are the three causes of swelling: the changing nature of strength of bonds between atoms (including and leading to change of the crystal structure) - examples: BeO increases by 16%, diamond - 50%, GdAlO3- 6% (C. M. Kosenkov. X-ray diffraction effects and swelling of some non-metallic materials after neutron irradiation. Radiation materials science. T. 7. Proceedings of the International conference on R. the emer: stainless steel, an increase of 20% (C. Cawthorue, E. J. Fulton. Voids in irradiated stainloss steel. Nature, 216 (1966), 5115 N, R. 575); the formation of gas bubbles - example: B4C, increase by 40% (M. S. Kovalenko centuries, gardeners. Radiation damage to the material of the reflector. M: Atomizdat, 1979).As a result of these events disrupted the normal maintenance of the reactor, burst protective steel shell elements with absorbing (B4C) and reflecting (BeO) materials.Developed techniques to combat swelling of various materials. There is a method of preparation of reactor materials, which consists in obtaining the crystal structure more resistant to neutron irradiation. The dysprosium titanate is used as the absorber, with the equilibrium structure of the pyrochlore type, the radiation enters the structure of fluorite type with a volume increase of more than 4%. The training material is that it pre-irradiated in a fast neutron flux, which does not change the absorption ability of dysprosium, to fluence, when there is a transition in the structure of fluorite. For subsequent use in a nuclear reactor the amount of dysprosium titanate increases not more than irradiation;
the induced radioactivity of the material increases the technological difficulties of its further use;
significant methodological limitations in the implementation of this method.A known method of improving the radiation resistance of stainless steels by cold deformation by 20 - 30% . Arise during the deformation dislocations and other distortion patterns affect the dynamics of accumulation and aggregation of point defects that occur during irradiation, which leads to decrease swelling.The disadvantage of this method is limited its scope only to the plastically deformable materials (metals).Thus, before the creators and operators of nuclear technology has always stood and task - reduction of swelling materials from neutron exposure.The present invention is to increase the radiation resistance of materials used in the fields. This is achieved by the fact that preparation for use in neutron fields materials are shock-wave impact of the explosion, resulting in their deformation. In the preparation of predominantly non-metallic material is P in the range of 1 GPA <P Shock waves and phenomena of high-speed deformation of metals, edited by Meyers, M. A., Murer L. E., metallurgy, 1984, page 512; Batsanov C. S., frost, E. M., Kasutin B. N. Effect of an explosion on the matter, Journal of structural chemistry, 1970, T. II, vol. 1, page 156; Adadurov, A., goldanskii Century. N. "Advances in chemistry, 1981, T. 50, page 1810).From General considerations it is clear that each extra location or any other entity that is a drain for the primary radiation defects, reduces the amount of swelling.As a result of application of the proposed method in forming high concentration of lattice defects, which affect the dynamics of primary radiation defects: vacancies and displaced atoms. As drains for primary defects, distortion patterns, the formation of the inventive method of processing of the material, removes them from the process of the formation of secondary defects clusters of defects of various types, which leads to the reduction of the swelling of the material compared to the swelling of those materials that have not undergone the claimed process.An example implementation of the proposed method.Was selected four ceramic substances belonging to different classes according to their crystalline characteristics. The gadolinium aluminate (GdAlO3) the IPA bias. Aluminum nitride (AlN) and zinc oxide (ZnO) are substances with temperature phase transitions reconstructive type. These two substances have different mechanisms of radiation damage of the crystal lattices. GdAlO3and Gd2Ti2O7was seen as absorbing compositions, AlN is used in magnetic sensors operating in neutron fields thermonuclear reactor, ZnO is similar for the crystallographic analysis-chemical structure of beryllium oxide (BeO), and has with him the same effects of radiation damage (C. M. Kosenkov. X-ray study of radiation damage in beryllium oxide and other compounds with lattice wurtzite. The dissertation. The Melekess, 1968).In the context of the stated objectives of the original samples were subjected to the shock-wave effects generated by explosives with pulse amplitude 1 - 23 GPA.Then blasted material along with the original were irradiated in the reactor CM-2 fluence to 11021n/cm2at a temperature of 100oC. the Results showed that after treatment with the explosion with the amplitude of the pressure pulse 1 HPa swelling blown materials within chuvstvitelnostyu explosion with pressure amplitude 23 HPa swelling GdAlO3accounted for 73% of the swelling of the source material, Gd2Ti2O7- 71%, AlN - 38%, and ZnO - 24 %.Thus, there is a significant reduction in the lattice swelling of ceramic materials, processed by the blast.Introduction processing by the explosion in technology training reactor materials experiencing significant swelling in the irradiation will reduce the amount of swelling that will reduce the load on the absorbing shell and other elements of the active zone, will prevent their failure from loss of containment shell which will increase the resource of the corresponding elements and components of the active areas, will enhance the safety of nuclear reactors. Because many of the materials of the active zones are used in the form of a powder, pour into a metal shell (BeO, B4C, GdAlO3), the application of the proposed method will not increase the cost of subsequent technological operations training blasted materials for use in nuclear reactors. For each material, the pressure in the pulse amplitude of the explosion must be chosen from considerations of valid values swelling and economic aspects of the interval 1-100 HPa (100 HPa is almost dollah, including the effects of the materials, resulting in their deformation, characterized in that in the preparation of predominantly non-metallic materials subjected to shock-wave impact generated by explosives, with the amplitude of the pressure P in the range of 1 GPA < P 100 HPa.
FIELD: atomic power engineering.
SUBSTANCE: device has welding chambers having apertures for inputting covers for pressurization, which concurrently are output apertures of heat-conductive elements, welding chambers electrodes, power source, transporting module for transverse product feed, common control system with blocks for parallel and serial connection, device for forming a break in secondary contour. Welding chambers are placed in parallel to each other at distance from each other, determined from formula S=t(m k+1), where S - distance between chambers axes, t - step of transport module, k - number of chambers in device equal to number of steps of transporting module in each singular step thereof, m - any integer starting from one, and control systems connected through parallel connection block to working tools of device of same names, and through block for serial connection to welding force drive and to device for forming break in secondary contour of power source, as well as to power source connected in parallel to welding chambers electrodes.
EFFECT: higher efficiency.
4 cl, 1 dwg
FIELD: nuclear power engineering; manufacture of fuel elements and their claddings.
SUBSTANCE: each weld of cladding and its plug are tested in facility equipped with units for clamping and revolving the claddings, scanning with carriage using weld inspection piezoelectric transducer and piezoelectric transducer for measuring wall thickness in measurement region, immersion bath, ultrasonic pulse generator, ultrasonic pulse receiver, microprocessor, analog-to-digital converter switch, and random-access memory.
EFFECT: enhanced quality of fuel elements and their operating reliability in reactor core.
1 cl, 1 dwg
FIELD: power engineering, namely nuclear power reactors, particularly sealing of fuel elements by means of contact butt welding with use of plugs.
SUBSTANCE: apparatus includes sealed welding chamber with housing non-detachable at operation and having through duct for feeding parts to welding zone; mechanisms for sealing welding chamber; device for feeding parts to welding zone; additional clamp of tube; mechanisms for gripping and fixing welded parts; drive device for supplying welding pressure; autonomous drive units. Mechanisms for gripping and fixing welded parts are in the form of collet chucks with respective drives. Welding pressure supply drive device is connected with electrode holder of plug. Welding chamber is restricted by non-detachable housing and flange-current supply lead that is fluid -tightly connected with housing and fixed relative to housing at operation. One collet chuck has annular detachable current supply lead in the form of sectors and it rests by its end at side of large base of petal cone upon said flange-current supply lead. Collet chuck of tube grip and electrode-holder of plug have coaxial electrically insulated one relative to other tie rods arranged in through duct of chamber and joined with autonomous drive units.
EFFECT: enhanced stability of process, improved quality of welded joint due to lowered misalignment of tube and plug.
FIELD: nuclear power engineering; manufacture of fuel elements for fuel assemblies of nuclear power reactors.
SUBSTANCE: proposed process line has mechanism for press-fitting bottom plug in calibrated end of can provided with cutoff gear for piece-by-piece feeding of bottom plugs of different types that incorporates bottom plug passage duct accommodating C-shaped member with reciprocating horizontal-motion actuator whose top flap has slot engageable with upper cylindrical part of bottom plug; bottom flap is longer than top one and is provided with bottom plug passage hole shifted toward edge of bottom flap; flaps are spaced apart through distance slightly longer than maximal length of thick end of bottom plug; rod designed for press-fitting bottom plug in calibrated end of can has bed with seat to receive bottom plug, maximal-size portion of seat following shape of bottom plug.
EFFECT: enlarged functional capabilities of process line for manufacturing fuel-element cans of different sizes.
1 cl 7 dwg
FIELD: mechanical engineering.
SUBSTANCE: proposed method is intended for manufacturing fuel elements using resistance-butt welding primarily for their joining to zirconium alloy cans. Welding is effected at equipment electrical resistance not over 30-fold resistance of can section forming welded joint having or not point discontinuities in the form of separate spots or chain of such spots forming no continuous line and measuring maximum ten thicknesses of weld in cross-sectional area of welded joint under check disposed at distance equal to two or three thicknesses of can wall from butt-end of plug located inside fuel element, welded joint being checked by uniformity of external fin. Length of poor fin formation section does not exceed 10% of joint perimeter.
EFFECT: enhanced quality of welds and reliability of fuel element sealing.
FIELD: nuclear power engineering; tubular dispersed-core three-layer fuel elements.
SUBSTANCE: proposed method includes production of powder mixture, powder mixing in plasticizer environment, cold molding in core billet with plasticizer, thermal sintering, hot molding-calibration of fuel core, core placing in can made in the form of sleeve with annular slot, calibration, hot molding through die, and drawing; inner surface of external can of sleeve is provided with longitudinal bulges and outer surface bears bulge location marks; fuel core is provided with longitudinal flats and placed in sleeve taking care to align bulges of the latter with core flats; in the course of drawing marks are aligned on arbor ribs.
EFFECT: enhanced stability of active layer and can thickness in shaping polyhedral fuel elements.
1 cl, 4 dwg
FIELD: nuclear power engineering.
SUBSTANCE: proposed fuel assembly primarily designed for use in nuclear power reactors VVER-1000 and VVER-440 has composite bottom spacer grid built of at least two parts identical with respect to disposition of holes and total thickness of component parts equal to height of circular collar on bottom plug of fuel element, and tubular channel hole diameter for bottom plugs equal to diameters of lower ends of bottom plugs; the latter are secured in holes of aligned parts of bottom spacer grid by shifting component parts of bottom spacer grid relative to each other, by locking bottom plugs on circular collar of bottom plugs between annular projections of upper and lower parts of bottom spacer grid, and by aligning flow holes of bottom spacer grid component parts. Component parts of bottom spacer grid are rigidly fixed upon their shifting to bottom nozzle of fuel assembly in case of nonseparable type of assembly and loosely attached upon their shifting to bottom nozzle in case of separable type of assembly.
EFFECT: enhanced reliability of fixing fuel element plugs in bottom grid holes of separable and nonseparable fuel assemblies, reduced labor consumption for manufacture and assembly.
1 cl, 3 dwg
FIELD: nuclear power engineering; manufacture of fuel elements for fuel assemblies of power reactors.
SUBSTANCE: proposed process line has mechanism for weighing can charged with fuel pellets installed past retainer press-fitting mechanism; can is coupled through computer with mentioned weighing mechanism for outputting data on pure mass of pellets in can; γ-quanta detecting units and pellet enrichment automatic control installations are mounted on charged can guiding facility in the form of rolling train between its rollers throughout length of charged pellet stack; detecting units are disposed around pellet stack charged in can with collimation channels shifted throughout length of charged pellet stack; detecting units are provided with photoelectronic multipliers, spectrometers, and data acquisition, processing and outputting computer. Each detecting unit is provided with through hole passing can-displacement tungsten tube; shifted collimation channels are provided in top and bottom parts of tungsten tube; photoelectronic multipliers are disposed on butt-ends of detecting unit.
EFFECT: enhanced quality of fuel element manufacture.
3 cl, 3 dwg
FIELD: nuclear power engineering, possibly automatic line for producing fuel elements of fuel assemblies of power nuclear reactors.
SUBSTANCE: aggregate is provided with detachable device for measuring electric resistance of fitting. Said device is arranged between collet chucks being in open position and it is made of two dielectric members spring-loaded one relative to other. End of one of said members has shape corresponding to contour of annular turning formed coaxially on end of collet chuck for plug. End of second member has shape corresponding to contour of annular turning formed coaxially on end of fitting in collet chuck for fuel element envelope. Said device has spring-loaded contacts for measuring electric resistance between fitting inside collet chuck and collet chuck itself. Caprolactam is used as dielectric material.
EFFECT: enhanced efficiency and quality of contact butt welding at sealing fuel element.
2 cl, 3 dwg
FIELD: nuclear power engineering.
SUBSTANCE: members used for fastening fuel element in hole of bottom end spacer grid are made in the form of shortened plug that has coaxial blind hole on its butt-end formed by annular walls expanded (burnished) in hole of larger diameter within bottom end spacer grid.
EFFECT: enhanced reliability of fuel assembly, reduced manufacturing cost and structural material input.
1 cl, 3 dwg