A fuel assembly of a nuclear reactor heat output from 1150 mw to 1,700 mw

 

The invention relates to atomic energy and can be used, in particular, in the construction of fuel assemblies (FA) active zones of nuclear power reactor thermal power from 1150 to 1700 MW, especially for reactors VVER-440. A fuel Assembly of a nuclear reactor contains a hexagonal bundle of fuel elements placed along the length of the Assembly spacer grids of the head and tail parts. The head portion, the tail portion and the spacer grids are rigidly connected to the supporting elements made in the form of angular plates of zirconium alloy. The width of the beam plate is selected from 0,117N to 0,177N, where N is the size of the fuel Assembly “turnkey”. Technical result - increased rigidity of the bundle of fuel elements and the entire Assembly as a whole, the possibility of collision beam rods with case, reduces the non-uniformity of energy deposition by volume of the fuel Assembly. 1 N. and 5 C.p. f-crystals, 2 Il.

The technical field to which the invention relates

The invention relates to nuclear energy, in particular to the structures of theprovides the La enhancements and modernization of existing reactor type VVER-440.

The level of technology

Known fuel Assembly, which can be used to form the active zone of reactor VVER-440 (EN 2126999, G 21 1/04, 27.02.99). A fuel Assembly contains from 216 to 270 rod fuel elements (cartridges), with the outer diameter of the shell from 5.85 to 6.17 mm and/or from 6,66 to 6.99 mm Step installation of the fuel rods in a hexagonal lattice in the fuel assemblies and their diameter is selected based on the conditions of providing value Vodorezova relations from 1.6 to 2.0. Known fuel Assembly has a high efficiency under normal operating conditions and in emergency conditions. An active area formed of such fuel assemblies, allows you to extend the range of the maneuvering capacity of the reactor, to increase the burnup of nuclear fuel. In this fuel Assembly reduced the likelihood of seal failure of fuel elements that led to the use of fuel elements with a diameter less than the diameter of standard fuel elements. Known fuel Assembly is a promising development and can be used in the formation of a fundamentally new active zone of reactor VVER-440.

The closest Thea Assembly of a nuclear reactor heat output from 1150 to 1700 MW, containing a hexagonal bundle of fuel elements placed along the length of the Assembly spacer grids of the head and tail parts (Nigmatulin, I. N., Nigmatulin B. I. Nuclear power plant. M.: Energoatomizdat, 1986, S. 116). The active zone of reactor VVER-440 with internals fixed inside the reactor vessel and formed of 349 fuel assemblies. Fuel assemblies are divided into still installed in the active zone (working TVs in the amount of 312 units) and control fuel assemblies (two-storey emergency-regulating FAS in the amount of 37 units), able to move in the vertical direction.

Known fuel Assembly used for forming reactor type VVER-440 consists of 126 rod fuel elements with a diameter of 9.1 mm, which are placed in the hexagonal cavity of the cover, the ends of which are connected to the head part and the tail part. Fuel elements mounted on the lower supporting bars and distanceunits in the beam in increments of 12.2 mm through eleven cell grid spacers, pre-formed in the frame on the Central tube. Construe and fuel elements in the cells of the spacer grids, what is needed to compensate for non-uniformity of temperature and radiation extensions rods that occur during operation.

Thus, the bundle of fuel elements in the known fuel Assembly is fixed only by means of the upper and lower support grates and located between grid spacers, forming the frame of the beam. The result is the deterioration of the fuel element cladding under polevkami grid spacers with the formation of gaps at junctions, the wear surfaces of fuel elements in the impact of foreign objects, which in cases of abrasion of the shell through cause depressurization of the fuel rods and worn rims grid spacers. The weakening of the rigidity of planting, emergence and development gaps of the fuel rods in the cells of the grid spacers is determined by the reduction in the diameters of rods and wear in places of contact of the rods with polevkami cell grid spacers flowing in vibration of the fuel rods in the bundle and the bundle of fuel rods in the case of hydrodynamic impact pressure of flow. Collision beam rods with case and collision in which is formed during operation of zazzali rods, which manifests itself in terms of vibration.

In addition, the presence of the cover makes a “parasitic metal in the active area increases linear heat load of the fuel elements due to involuntary step increase between fuel assemblies increases the non-uniformity of energy deposition by volume of the fuel Assembly, worsens the conditions of heat exchange in emergency situations associated with loss of coolant, etc.

The invention

The present invention is the creation and development of a fuel Assembly of a nuclear reactor heat output from 1150 to 1700 MW, providing increased safety of operation in the active zone of the nuclear reactor while increasing efficiency.

The solution of this problem can be obtained new technical results, namely, that increases the rigidity of the bundle of fuel elements and the entire Assembly as a whole, the possibility of collision beam rods with case, reduces the non-uniformity of energy deposition by volume of the fuel Assembly.

These technical results are achieved by the fact that in the fuel Assembly of a nuclear reactor heat output from arc the spacer grids, the head and the tail portion, the head portion, the tail portion and the spacer grids are rigidly connected to the supporting elements made in the form of angular plates of zirconium alloy, and the width D of the beam plate is selected from 0,117N to 0,177N, where N is the size of the fuel Assembly “turnkey”.

The distinctive feature of this invention consists in the following. The head portion, the tail portion and the spacer grids are rigidly connected to the supporting elements made in the form of angular plates of zirconium alloy, forming a single frame for the bundle of fuel elements and the entire Assembly as a whole, which significantly reduces vibration beam rods. For this purpose, the width D of the beam plate is selected from 0,117N to 0,177N, where N is the size of the fuel Assembly “turnkey”. When the value of the width d of the beam plate less 0,117N angular stiffness of the plates is not enough to secure the bundle of fuel elements that will vibrate during operation both in axial and in radial directions. If the width d of the beam plate more 0,177is esedo by increasing the surface contact angle plates. In addition, in this case, the uneven cooling of the fuel rods in the cross section of the Assembly, because the profile of the coolant flow in the right areas and in other areas of the Assembly is different.

It is advisable hexagonal bundle of fuel elements to perform step was 12.75 mm

In addition, angle plates can be connected to a head part and a tail part by demountable connection, which used a threaded connection in the form of screws threaded portion which cooperates with mating threads, made in the head and tail parts of the Assembly.

The corner of the plate it is advisable to connect with the spacer bars by means of non-separable connections, such as welding.

Analysis of the solutions known from the prior art has not revealed any device, coinciding with the described invention, the totality of significant, included in the independent claim, which indicates that the present invention meets the condition of patentability “novelty.”

The prior art fuel Assembly of a nuclear reactor containing a portion of the characteristics with the characteristics described invention - EN 2093906, C1, G 21 is of 1000 MW. Common symptoms are known and the present invention are signs concerning the availability of supporting elements in the form of angle plates are made of zirconium alloy and rigidly connected with the rear part and the spacer bars. With the main part of the angular plate in the known device is not connected, which does not allow to use them as a single frame bundle of fuel elements and assemblies. In the known device the rigidity of the Assembly together form a load-bearing channels. Thus, the combination of distinctive features of the present invention from the prior art is not known, and known features do not allow to obtain the result, consisting in a simultaneous increase in the rigidity of the bundle of fuel rods and the entire fuel Assembly as a whole. Therefore, the present invention meets the condition of patentability “inventive step”.

In Fig.1 shows a General view of a fuel Assembly of a nuclear reactor; Fig.2 shows the section a-a in Fig.1.

Information confirming the possibility of carrying out the invention

A fuel Assembly of a nuclear reactor contains hexagonal beam 1 fuel elements 2 placed in spaced pustka connected to the support elements, made in the form of angle plates 6 of zirconium alloy. The width D of the beam 7 of the plate is selected from 0,117N to 0,177N, where N is the size of the fuel Assembly “turnkey”.

The described design of the fuel Assembly refers to structures with a rigid skeleton, which consists of a head part 4, the tail part 5, grid spacers 3 and the corner plates 6. The corner of the plate 6, it is advisable to weld to the rims grid spacers 3, and with the head part 4 and rear part 5 is connected via screws. This fuel Assembly eliminates the gap between the spacer bars and a case that allows you to increase the spacing of the fuel rods to (12,65 rates at 12.75) mm No cover reduces the amount of parasitic metal in the core is about 10 kg of zirconium alloy on each build.

Thus, in the described fuel Assembly increases fuel efficiency, reduces the non-uniformity of energy deposition by volume Assembly and ensures the alignment of the coolant flow in normal operating conditions, under abnormal operating conditions and in emergency conditions. Using the century

Claims

1. A fuel Assembly of a nuclear reactor heat output from 1150 MW to 1,700 MW, containing a hexagonal bundle of fuel elements placed along the length of the Assembly spacer grids of the head and the tail portion, wherein the head portion, the tail portion and the spacer grids are rigidly connected to the supporting elements made in the form of angular plates of zirconium alloy, and the width d of the beam plate is selected from 0,117N to 0,177N, where N is the size of the fuel Assembly “turnkey”.

2. A fuel Assembly of a nuclear reactor under item 1, characterized in that the hexagonal bundle of fuel elements made from step was 12.75 mm

3. A fuel Assembly of a nuclear reactor under item 1 or 2, characterized in that the angular plate is connected to a head part and a tail part through a gasketed connection.

4. A fuel Assembly of a nuclear reactor under item 3, characterized in that as a demountable connection used threaded connection in the form of screws threaded portion which cooperates with mating threads, made in the head and tail is the angular plate is connected to the spacer bars by means of non-separable connections.

6. A fuel Assembly of a nuclear reactor under item 5, characterized in that as a non-separable connection used welding.

 

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FIELD: nuclear power engineering.

SUBSTANCE: proposed fuel assembly affording supercritical neutron-physical state under normal operating conditions of nuclear reactor and subcritical state of fuel assembly during loss-of-coolant and boiling accident has vertical process channel accommodating fuel elements mounted on supporting blocks which are alternating with absorbing blocks of which at least some of them are provided with cavity communicating with process channel space and filled with absorber in the form of boron powder enriched by boron-10 isotope conveyed in emergency situations by boiling coolant into process channel. Some of absorbing blocks accommodate combustible absorber.

EFFECT: enhanced inherent ability of self-protection and safety of pressurized-tube reactors.

3 cl, 1 dwg

FIELD: nuclear power engineering; fuel assemblies of water-cooled reactors.

SUBSTANCE: proposed debris entrainment filter is made in the form of plate with holes formed as V-shaped slots organizing adjacent rows, slot length obeying dependence L ≥ 5 S; slots may be disposed in row in mirror image or row may be formed by alternating slot branches of adjacent rows.

EFFECT: ability of entrapping most fine particles without increasing fuel assembly pressure drop.

3 cl, 4 dwg

FIELD: nuclear power engineering; fuel compositions for nuclear-reactor fuel elements.

SUBSTANCE: can of desired size is filled with finely dispersed fuel and in addition with material forming solid matrix at temperature equal to or higher than fuel melting point. This can filled with finely dispersed fuel and material forming solid matrix is heated to temperature equal to or higher than fuel melting point is heated and cooled down.

EFFECT: enhanced fuel density and resistance to destruction at meltdown accidents.

7 cl, 2 dwg

FIELD: nuclear engineering; nuclear reactor fuel elements.

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EFFECT: enhanced mechanical strength of structure and corrosion resistance of weld, improved hydraulic characteristics of fuel element.

4 cl, 2 dwg

FIELD: nuclear engineering; mechanical design of power reactor fuel elements.

SUBSTANCE: proposed nuclear reactor fuel element has can and plugs. Can is filled with nuclear fuel. Plugs are welded to can. One of welds is positioned first along coolant flow within reactor and is disposed under external surface of can so that plug is deepened into the latter. Can has external section and that welded into fuel element can. The latter section whose diameter is smaller than outer diameter of fuel-element can but greater than its inner diameter is terminated with external dross squeezed out of weld. External section of plug is disposed directly past weld. This plug section is made in the form of cylindrical member turning into conical end of diameter smaller than or equal to maximal diameter of fuel-element can but larger than diameter of plug section welded into can. External dross is disposed between butt-end of fuel-element can and butt-end surface of plug external section joining the latter with generating surface of section welded into can.

EFFECT: enhanced manufacturability and reduced pressure drop over reactor coolant flow.

2 cl, 3 dwg

FIELD: nuclear power engineering; power reactor fuel elements.

SUBSTANCE: proposed nuclear-reactor fuel element has can sealed with plugs to maintain atmosphere of desired composition therein and pelletized nuclear fuel of enriched uranium disposed within can. Pellets are provided with axial hole and are assembled in fuel column terminating on both ends with shields made of depleted uranium and held tight against fuel column and against one of plugs by means of lock. The latter is disposed in expansion volume of fuel element can. Surfaces of fuel column and shields adjoin inner surface of can in a spaced relation to the latter. Cylindrical pellets form shield. They have axial hole whose axial diameter amounts to 1.2-2.3 of that of pellet column hole. Hole between surface of shields and inner surface of pellets amounts to 1.0-1.3 of clearance between fuel column surface and inner surface of can.

EFFECT: facilitated manufacture of fuel elements, enhanced in-service safety of reactor core incorporating proposed fuel elements.

1 cl, 1 dwg

FIELD: physics.

SUBSTANCE: fuel assembly of a nuclear reactor consists of batch of fuel elements and guide channels, installed in spacer grids, head section and end section. The spacer grids are joined together as well as with the end section by elements, located along the length of the fuel assembly. The end section consists of a bedplate and a support body joined together. On top of the bedplate there is an anti-vibration grid, consisting of cells joined together. The anti-vibration grid, bedplate and the support body are joined together by at least one fastening element.

EFFECT: longer lifespan of the fuel element and fuelling and increased burn up fraction of the fuel.

4 dwg

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