CN1836291A - Fuel assembly for a nuclear reactor - Google Patents

Abstract

The invention can be used for fuel assembles in nuclear engineering, in particular for the structure of a rigid framework. The inventive fuel assembly consists of head and rear parts which are connected to each other by guiding channels arranged in cells of spacer grids. Said guiding channels are rigidly connected at least to end spacer grids. The height (h) of the spacer grids and the wall thickness ( delta ) of the cells thereof are selected in such a way that the quantitative characteristics thereof correspond to a calculatedly-and-experimentally determined condition. Said invention makes it possible to improve assembling rigidity at transversal and longitudinal bending, to increase an angular rigidity of the </= a guiding channel-a cell of spacer grid >/= pairs, to reduce the fuel assembly bending in its own plane between the spacer grids and the free bending of the fuel assembly in non-homogenous neutron and temperature fields by the decreased tendency of a E635 alloy to radiation growth.

Description

The fuel assembly that is used for nuclear reactor

Technical field

The present invention relates to nuclear energy engineering, and concrete relate to a kind of structure that is used for the fuel stringer assembly of water deceleration power reactor, the reactor of VVER-1000 type more particularly, and relate to a kind of structure of element of rigid frame more specifically.

Background technology

A kind of fuel stringer assembly is known in the art, and it comprises bundled fuel rod (Kramerov A.Ya., the Design Issues ofNuclear Reactor of the pore chamber (cell) that is arranged in screen work, M., Atomizdat Publishers, 1971, p198, Fig.7.2.2).The hardness of described fuel stringer assembly is guaranteed by the existence of the hexagon housing of top that is connected described assembly and caudal components with rigidity.But the existence of described housing causes parasitic neutron capture in the core, and since the distance between the fuel stringer assembly be forced to increase, increased the linear thermal force on the described fuel rod.

A kind of fuel stringer assembly is known in the art, it comprises hexagonal fuel bundle, described fuel bundle is arranged in the pore chamber of screen work (spacer grid), described screen work is along length setting (Kramerov A.Ya., Design Issuesof Nuclear Reactors, the M. of described assembly, Atomizdat Publishers, 1971, p.204, Fig.7.1.11b).The top of described assembly is connected by guide channel with caudal components, and rod comprises the material of intercept neutrons herein.Described fuel stringer assembly does not have housing, and this makes it possible to reduce the gap between the adjacent fuel stringer assembly.As a result, reduced linear load on exergonic scrambling and the fuel rod.

Not existing of housing reduced parasitic neutron capture, and reduced material consumption.But this assembly demonstrates in the use on the power unit that is equipped with VVER-1000 type reactor: after operation in 3 years, because mechanical load from the side of described top component, described guide channel limpens, and described top component is compacted to prevent that fuel stringer assembly from upwards floating under the effect of cooling medium.Except this, in the process of operating reactor, because hot mechanical load appears in the distortion of fuel rod on whole modular construction; The screen work transmission of this distortion by being out of shape equally.In the evolution of the bending in fuel stringer assembly, topmost contribution is to be made by the elastic preload that discharges in the screen work, and described elastic preload is to produce in the process that fuel rod is placed in screen work and the guide channel.

The remarkable reduction of the bending stiffness of fuel stringer assembly can fundamentally change its performance in core in the long-time running process, just: in the fuel stringer assembly of complicated spatial structure, occur crooked, described assembly axis runout initial position is until maximum permissible value simultaneously, consider the construction package gap, this maximum permissible value is produced by the geometry possibility that is placed on this assembly in the core.Equally, big gap can occur between the fuel rod of the periphery of the fuel stringer assembly of adjacent flex, this can destroy thermal technology's reliability of those fuel rods because the energy in fuel rod discharges to fluctuate.Equally, it should be noted that, hexgonal structure for fuel stringer assembly, particularly those are used in the hexgonal structure of the fuel stringer assembly in the energy unit that is equipped with VVER-1000 type reactor, observed the angle anisotropy (bending stiffness that is not equal to " from the end face to the end face " along the bending stiffness of " from the angle to the angle " direction) of bending stiffness, and assembly along the bending stiffness of tangential direction (with respect to the center of described core) less than its bending stiffness radially.Cause the bending that is mainly the eddy current shape of core along the big degree of freedom of moving of tangential direction, and therefore, caused the maximum deflection of fuel stringer assembly in operation conditions.Some data can obtain, i.e. the bending of fuel stringer assembly is 20 millimeters magnitude.This remarkable fail in bending of fuel stringer assembly the initial geometric configuration of core, make the energy changed core discharge and the thermal-hydraulic performance.

For the above-mentioned shortcoming of eliminating fuel stringer assembly and the stable performance that guarantees it, promptly in the operation conditions of 4-5, eliminate the overbend of fuel stringer assembly, need:

-by introducing side member to guarantee the guarantee value of fuel stringer assembly in the bending stiffness at transverse curvature place, wherein during whole service, described side member is not slided with respect to screen work;

-guarantee value assurance, higher of fuel stringer assembly by taking following measure in the bending stiffness at transverse curvature place, promptly by reducing the bending in operation conditions in single bar or the scope of other side member between screen work, and increase the rod in the pore chamber of screen work or the rotational stiffness (turning stiffness) of side member simultaneously.

A kind of fuel stringer assembly, it technological essence and the effect of realization aspect approach described one most, and comprise top and caudal components, described top is connected with the guide channel of caudal components by the pore chamber that is arranged in screen work, described screen work is along the certain distance setting that is spaced from each other of the length of described assembly, this fuel stringer assembly is followed described condition (RU 2093906, G 21 C 3/30,10/20/1997).The structure of known fuel stringer assembly is utilized other reinforcing element---and vertically angle section replenishes, and described reinforcing element extends to higher screen work from lower support grid, and is welded to each screen work on the outside at six angles.Being rigidly connected of angle section and screen work guaranteed the remarkable increase of transverse curvature rigidity, and this increase does not rely on the release of the elastic preload in the bar system of fuel stringer assembly.The spatial form of angle section has the value of their very large moment of inertia, guarantees the sufficient rigidity of described structure at the transverse curvature place of fuel stringer assembly thus.In addition, with respect to the axis of screen work in their position fastened to each other, rotate angle section possibility do not have the rigidity that helps fuel stringer assembly usually.

Simultaneously, known fuel stringer assembly has following shortcoming:

-having increased the metal consumption of structure, this makes the neutronics characteristic that has reduced core;

-at that tilt and the fuel rod place periphery, it is poorer that heat dissipation becomes;

-owing to introduced the element of other inclination, make the technical sophistication of fuel stringer assembly, welding and controlled quentity controlled variable increase;

-in the stage of making and in operational process, the possibility of visual control reduces.

Summary of the invention

The objective of the invention is to develop and make a kind of fuel stringer assembly that is used for nuclear reactor, when being operated in the fuel recycle of longer time, it will have higher stability, can not accumulate unallowed bending simultaneously, and reduce material consumption simultaneously.

Solved this problem, can realize new technique effect, described technique effect is to increase the rigidity of fuel stringer assembly in horizontal and vertical knee, angular rigidity (angular stiffness) in paired " pore chamber of guide channel-screen work " will increase, interior in the span scope of fuel stringer assembly between screen work will reduce in bending, and owing to the trend of E635 alloy for the reduction of radiation growth (radiation growth), the free bend of fuel stringer assembly in irregular neutron and temperature field will be lowered.

Owing to the following fact has realized described technique effect, promptly be used for the fuel stringer assembly of nuclear reactor, wherein this assembly comprises top component and the caudal components that is connected by guide channel, described guide channel is arranged in the pore chamber of screen work, described screen work is provided with along the length each interval certain distance of this assembly, described guide channel is rigidly connected with the screen work of end at least, and the wall thickness δ of the height h of screen work and the pore chamber in the screen work is selected such that their numerical value satisfies following condition:

$C_0{\left(\frac{h}{20\left[\mathrm{mm}\right]}\right)}^{-a}\&times;{\left(\frac{\mathrm{\&delta;}}{0.25\left[\mathrm{mm}\right]}\right)}^{-b}<1.0,$ Wherein

$a=A_0+A_1(\frac{h}{20\left[\mathrm{mm}\right]}-1.5)+A_2{(\frac{h}{20\left[\mathrm{mm}\right]}-1.5)}^2;$

$b=B_0+B_1(\frac{h}{20\left[\mathrm{mm}\right]}-1.5)+B_2{(\frac{h}{20\left[\mathrm{mm}\right]}-1.5)}^2+B_3{(\frac{h}{20\left[\mathrm{mm}\right]}-1.5)}^3+B_4(\frac{\mathrm{\&delta;}}{0.25\left[\mathrm{mm}\right]}-1.2);$

The height of h-screen work, millimeter;

The thickness of the element of the pore chamber of δ-formation screen work, millimeter, wherein, for 8 screen works, C ₀=39.17, A ₀=5.563, A ₁=-3.482, A ₂=1.332, B ₀=2.245, B ₁=-4.500, B ₂=6.072, B ₃=-3.128, B ₄=-0.620, for 9 screen works, C ₀=22.74, A ₀=4.988, A ₁=-2.985, A ₂=1.119, B ₀=2.225, B ₁=-4.005, B ₂=5.145, B ₃=-2.595, B ₄=-1.113, for 10 screen works, C ₀=13.06, A ₀=4.481, A ₁=-2.568, A ₂=0.932, B ₀=2.203, B ₁=-3.568, B ₂=4.324, B ₃=-2.127, B ₄=-1.510, for 11 screen works, C ₀=8.84, A ₀=4.138, A ₁=-2.281, A ₂=0.811, B ₀=2.170, B ₁=-3.250, B ₂=3.752, B ₃=-1.814, B ₄=-1.675, for 12 screen works, C ₀=6.90, A ₀=3.895, A ₁=-2.088, A ₂=0.732, B ₀=2.126, B ₁=-3.042, B ₂=3.400, B ₃=-1.623, B ₄=-1.695, for 13 screen works, C ₀=5.73, A ₀=3.697, A ₁=-1.937, A ₂=0.667, B ₀=2.068, B ₁=-2.910, B ₂=3.199, B ₃=-1.505, B ₄=-1.651, for 14 screen works, C ₀=4.70, A ₀=3.526, A ₁=-1.813, A ₂=0.614, B ₀=2.003, B ₁=-2.815, B ₂=3.062, B ₃=-1.422, B ₄=-1.575, for 15 screen works, C ₀=3.78, A ₀=3.356, A ₁=-1.684, A ₂=0.560, B ₀=1.940, B ₁=-2.722, B ₂=2.928, B ₃=-1.336, B ₄=-1.490.

Being rigidly connected of the distinctive screen work that is characterised in that guide channel and end at least of the present invention but preferred and all screen work, this prevents the pore chamber slip of guide channel with respect to screen work.In such a case, when it during by radiation, the overall bending stiffness of fuel stringer assembly improves, because the constant composition of assembly bending stiffness is connected the equal stiffness of framework with guide channel.Fuel rod can be not as the many bar systems that connect, and simultaneously, as a plurality of independently rods rather than as the bundle of the many rods that connect, sliding in the pore chamber of screen work to help the overall bending stiffness of restrainting, its value is very little.The rigidity of fuel stringer assembly will increase generally, if and when only satisfying following condition, its stability accesses assurance, wherein, the gap that is formed between the assembly in this stability can not exceed maximal value, described maximal value is possible from the angle of thermal technology's reliability of the rank (rating) of the permission of guaranteeing fuel rod and core, and described condition is:

$C_0{\left(\frac{h}{20\left[\mathrm{mm}\right]}\right)}^{-a}{\&times;\left(\frac{\mathrm{\&delta;}}{0.25\left[\mathrm{mm}\right]}\right)}^{-b}<1.0$

Except this, above-mentioned test design expression formula is relevant with the number of the screen work of the canonical parameter with them, wherein on this parameter, appear in the screen work and the stress of being regulated by axial force can not surpass permissible value, described axial force appears at the knee in the position of fixed guide passage.

Be to utilize the E635 alloy to make guide channel easily, and with the E310 alloy or preferably the E635 alloy make screen work.

Guide channel can with the screen work of end at least directly or the lining by the centre be rigidly connected, described lining is arranged in the corresponding pore chamber of screen work.Guide channel should preferably be made the distance symmetry that is no more than 0.15h with respect to the longitudinal axis of guide channel at the place, two ends of screen work, in the end from screen work with being connected of screen work.

Guide channel also can form by spot welding with being rigidly connected of end screen work at least.

The most effectively utilize 18 guide channels with diameter of 12-14 millimeter.

Description of drawings

Fig. 1 shows the general view of fuel stringer assembly;

Fig. 2 shows the cut-open view of the modification of unit A shown in Figure 1;

Fig. 3 shows the cut-open view of second modification of unit A shown in Figure 1.

Embodiment

The fuel stringer assembly that is used for nuclear reactor comprises top component 1 and the caudal components 2 that is connected by guide channel 3.Described guide channel 3 is arranged in the pore chamber 4 of screen work 5, and described screen work 5 is provided with along the length each interval certain distance of this assembly.Guide channel is generally 18, extends through to be symmetrically located at central passage 6 pore chamber on every side.Other pore chamber of screen work 5 holds fuel rod 7.Because guide channel 3 is rigidly connected to the screen work of end or preferably is connected to all screen works 5, so screen work 5 and guide channel 3 jointly form the rigid frame of fuel stringer assembly.The height h of screen work and the wall thickness δ of the pore chamber in the screen work are selected such that their numerical value meets following condition:

$C_0{\left(\frac{h}{20\left[\mathrm{mm}\right]}\right)}^{-a}\&times;{\left(\frac{\mathrm{\&delta;}}{0.25\left[\mathrm{mm}\right]}\right)}^{-b}<1.0,$ Wherein

$a=A_0+A_1(\frac{h}{20\left[\mathrm{mm}\right]}-1.5)+A_2{(\frac{h}{20\left[\mathrm{mm}\right]}-1.5)}^2;$

$b=B_0+B_1(\frac{h}{20\left[\mathrm{mm}\right]}-1.5)+B_2{(\frac{h}{20\left[\mathrm{mm}\right]}-1.5)}^2+B_3{(\frac{h}{20\left[\mathrm{mm}\right]}-1.5)}^3+B_4(\frac{\mathrm{\&delta;}}{0.25\left[\mathrm{mm}\right]}-1.2);$

The height of h-screen work, millimeter;

The thickness of the element of the pore chamber of δ-formation screen work, millimeter, wherein, for 8 screen works, C ₀=39.17, A ₀=5.563, A ₁=-3.482, A ₂=1.332, B ₀=2.245, B ₁=-4.500, B ₂=6.072, B ₃=-3.128, B ₄=-0.620, for 9 screen works, C ₀=22.74, A ₀=4.988, A ₁=-2.985, A ₂=1.119, B ₀=2.225, B ₁=-4.005, B ₂=5.145, B ₃=-2.595, B ₄=-1.113, for 10 screen works, C ₀=13.06, A ₀=4.481, A ₁=-2.568, A ₂=0.932, B ₀=2.203, B ₁=-3.568, B ₂=4.324, B ₃=-2.127, B ₄=-1.510, for 11 screen works, C ₀=8.84, A ₀=4.138, A ₁=-2.281, A ₂=0.811, B ₀=2.170, B ₁=-3.250, B ₂=3.752, B ₃=-1.814, B ₄=-1.675, for 12 screen works, C ₀=6.90, A ₀=3.895, A ₁=-2.088, A ₂=0.732, B ₀=2.126, B ₁=-3.042, B ₂=3.400, B ₃=-1.623, B ₄=-1.695, for 13 screen works, C ₀=5.73, A ₀=3.697, A ₁=-1.937, A ₂=0.667, B ₀=2.068, B ₁=-2.910, B ₂=3.199, B ₃=-1.505, B ₄=-1.651, for 14 screen works, C ₀=4.70, A ₀=3.526, A ₁=-1.813, A ₂=0.614, B ₀=2.003, B ₁=-2.815, B ₂=3.062, B ₃=-1.422, B ₄=-1.575, for 15 screen works, C ₀=3.78, A ₀=3.356, A ₁=-1.684, A ₂=0.560, B ₀=1.940, B ₁=-2.722, B ₂=2.928, B ₃=-1.336, B ₄=-1.490.

Described pore chamber can be made into any known shape.Screen work 5 and guide channel 3 are preferably made by zircaloy E635; Also can just utilize the E635 alloy to make guide channel, and make screen work in conjunction with E635 and E110 alloy with the E110 alloy.

Guide channel 3 is rigidly connected to screen work by the lining 8 of centre, and described lining 8 is arranged in the corresponding pore chamber of screen work.Being rigidly connected of guide channel and screen work 9 forms by spot welding, for example passes through arc welding.Being rigidly connected of described guide channel and screen work should be made into the longitudinal axis that the two ends from screen work, the distance that is no more than 0.15h in the end from screen work are symmetrical in guide channel.In such a case, the bending stiffness of guide channel is significantly increased.

Fuel stringer assembly of the present invention can commercial Application, and can be used in best water In the deceleration power producer, particularly the reactor of VVER-1000 type is especially worked as When making the braced frame structure.

Fuel stringer assembly of the present invention can be formed on any equipment for this purpose On, and do not require the new tool that manufacturing is main.

Claims (9)

1. fuel stringer assembly that is used for nuclear reactor, comprise the top component and the caudal components that connect by guide channel, described guide channel is arranged in the pore chamber of screen work, described screen work is provided with along the length each interval certain distance of this assembly, it is characterized in that, described guide channel is rigidly connected to the screen work of end at least, and the wall thickness δ of the height h of screen work and the pore chamber in the screen work is selected such that their numerical value satisfies following condition: $C_0{\left(\frac{h}{20\left[\mathrm{mm}\right]}\right)}^{-a}\&times;{\left(\frac{\mathrm{\&delta;}}{0.25\left[\mathrm{mm}\right]}\right)}^{-b}<1.0,$ Wherein

$a=A_0+A_1(\frac{h}{20\left[\mathrm{mm}\right]}-1.5)+A_2{(\frac{H}{20\left[\mathrm{mm}\right]}-1.5)}^2;$

$b=B_0+B_1(\frac{h}{20\left[\mathrm{mm}\right]}-1.5)+B_2{(\frac{h}{20\left[\mathrm{mm}\right]}-1.5)}^2+B_3{(\frac{h}{20\left[\mathrm{mm}\right]}-1.5)}^3+B_4(\frac{\mathrm{\&delta;}}{0.25\left[\mathrm{mm}\right]}-1.2);$

The height of h-screen work, millimeter;

The thickness of the element of the pore chamber of δ-formation screen work, millimeter, wherein, for 8 screen works, C ₀=39.17, A ₀=5.563, A ₁=-3.482, A ₂=1.332, B ₀=2.245, B ₁=-4.500, B ₂=6.072, B ₃=-3.128, B ₄=-0.620, for 9 screen works, C ₀=22.74, A ₀=4.988, A ₁=-2.985, A ₂=1.119, B ₀=2.225, B ₁=-4.005, B ₂=5.145, B ₃=-2.595, B ₄=-1.113, for 10 screen works, C ₀=13.06, A ₀=4.481, A ₁=-2.568, A ₂=0.932, B ₀=2.203, B ₁=-3.568, B ₂=4.324, B ₃=-2.127, B ₄=-1.510, for 11 screen works, C ₀=8.84, A ₀=4.138, A ₁=-2.281, A ₂=0.811, B ₀=2.170, B ₁=-3.250, B ₂=3.752, B ₃=-1.814, B ₄=-1.675, for 12 screen works, C ₀=6.90, A ₀=3.895, A ₁=-2.088, A ₂=0.732, B ₀=2.126, B ₁=-3.042, B ₂=3.400, B ₃=-1.623, B ₄=-1.695, for 13 screen works, C ₀=5.73, A ₀=3.697, A ₁=-1.937, A ₂=0.667, B ₀=2.068, B ₁=-2.910, B ₂=3.199, B ₃=-1.505, B ₄=-1.651, for 14 screen works, C ₀=4.70, A ₀=3.526, A ₁=-1.813, A ₂=0.614, B ₀=2.003, B ₁=-2.815, B ₂=3.062, B ₃=-1.422, B ₄=-1.575, for 15 screen works, C ₀=3.78, A ₀=3.356, A ₁=-1.684, A ₂=0.560, B ₀=1.940, B ₁=-2.722, B ₂=2.928, B ₃=-1.336, B ₄=-1.490.

2. fuel stringer assembly according to claim 1 is characterized in that described guide channel is made by the E635 alloy.

3. fuel stringer assembly according to claim 1 is characterized in that, described screen work is made by E635 alloy or E110 alloy.

4. fuel stringer assembly according to claim 1 is characterized in that, described guide channel is rigidly connected to the screen work of end at least by the lining of centre, and described lining is arranged in the corresponding pore chamber of screen work.

5. fuel stringer assembly according to claim 1 is characterized in that being rigidly connected of described guide channel and screen work is made into to be symmetrical in from the two ends of described screen work the longitudinal axis of guide channel.

6. fuel stringer assembly according to claim 1 is characterized in that, being rigidly connected of described guide channel is positioned at the distance that is no more than 0.15h from the end of screen work.

7. fuel stringer assembly according to claim 1 is characterized in that, being rigidly connected of described guide channel and screen work forms by spot welding.

8. fuel stringer assembly according to claim 1 is characterized in that, the number of described guide channel is 18.

9. each described fuel stringer assembly in requiring according to aforesaid right is characterized in that the diameter of described guide channel is selected from 12 to 14 millimeters scope.

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