Regulating a fuel assembly water-cooled power reactor

 

The invention relates to fuel assemblies used for dual functions: energy production and regulation of the neutron flux in water-cooled nuclear power reactors, especially in nuclear reactors VVER-440. In regulating the fuel Assembly water-cooled power reactor mass of uranium dioxide in the beam, outer and inner diameters of the fuel cladding is from 69,16 kg to 159,25 kg, from 6.0010-3m to 8.0010-3m and 5,0910-3m to 6.7910-3m, respectively, for a beam of (174-216) fuel elements or mass of uranium dioxide in the beam, outer and inner diameters of the fuel cladding is from 88,67 kg to 149,53 kg, from 7,8010-3m to 8,7910-3m and 6,6210-3m to 7.4710-3m, respectively, for a beam of (132-168) fuel elements. This reduces the likelihood of leaks in fuel elements, expanding the range of the maneuvering capacity of the reactor and improving topliva.ispolzovanie is giving refers to nuclear energy and for the design of fuel assemblies, used for dual functions: energy production and regulation of neutron flux, especially in nuclear reactors with pressurized water VVER-440 (water-water energetic reactor for power unit with electric capacity of 440 MW).

The level of technology

The problem of improving the security of existing and newly designed nuclear power plants with water-cooled power reactors (VVER-440 has different solutions. Currently, this problem is solved, mainly by improving the reliability of protective systems, the improvement of individual nodes, optimization of regimes and regulations, etc. With virtually no issues for a substantial improvement in the cooling of fuel elements, fuel assemblies, especially in emergency conditions. This approach is largely due to the many years of very successful experience in the design and operation rod fuel elements used in conventional fuel assemblies, and in the composition of the governing assemblies (FCA).

Known for regulating a fuel Assembly of the reactor VVER-440 containing absorbent upper part and the lower part of the fuel (centuries Zverkov, E. I. Ignatenko, Aetna ARC is a working body of the control system and protection system (CPS) and provides a quick cessation of the nuclear reaction in the reactor is injected into the active zone of the neutron absorber and simultaneously removing from the active zone of its heat-generating part. In this mode, the Assembly functions as an emergency regulatory authority. During reactor operation by assembling carry out automatic adjustment in order to maintain reactor power at a given power level and transfer it from one power level to another. The Assembly is also used to compensate for changes in reactivity (poisoning of the reactor power and temperature effects) due to partial or complete removal of the absorber from the active zone.

Initially in the reactor set fuel portion in the cylinder, which then inserts the shank of the absorbing part. The connection parts made by means of an intermediate rod, which passes through the absorptive part and by capturing engages with the cylinder heat-generating part. With the upper part of the intermediate rod coupled to the rake drive the ARC through which moves the Assembly from its extreme upper position, in which the absorbing part is completely removed from the active zone, to the extreme lower position, in which the absorbing part is fully activated, and the fuel part is derived from it.

In the inner cavity of the absorbing part to ascertain the Assembly in the composition of the active zone in the region of a connecting node between the absorbing and heat-generating parts is a surge of thermal neutron flux, because the cavity of the docking station filled with water. Changing the position of the Assembly height of the active zone leads to an increase in burst thermal neutron flux, which has a negative impact on the working parameters of fuel assemblies located in the immediate vicinity of the regulating Assembly. The result is a nonuniform energy deposition height and radius of the active zone.

Closest to the technical essence and the achieved result is described regulating a fuel Assembly water-cooled power reactor containing absorbing neutrons an extension that is connected with the heat-generating part, containing hexagonal spacer grids, cells which are placed in the beam rod fuel elements from the fuel core of uranium dioxide, enclosed in a shell (WO 94/05013, G 21 7/103, 03.03.94).

In the known Assembly used in the intermediate absorber, which is part of the block, the retaining rod fuel elements, and represents the elements of hafnium made, in particular in the form of rods. The rods adjacent to the end face of the lattice with holes for passage of water and go between the fuel alealoveslauren elements, i.e. in the region of the head part of the bundle of fuel elements.

Elements of hafnium possess high physical efficiency and strong “push” energy field in several rows of fuel elements surrounding the cartridge of the ARC, and reduce the surge of thermal neutron flux in the region of the docking station and thereby reduce local bursts of energy deposition in the fuel elements of the working tapes neighboring regulating the fuel Assembly.

Along with modernization, concerning the availability of others rods in the area of the docking station, the famous Assembly of reduced outer diameter and inner diameter rod fuel elements and their quantity. In the beam of known ARC reactor VVER-440 contains 120 truss rods, made with an outer diameter 8,8010-3m and an inner diameter of 7.7010-3m and having an average linear thermal load on the fuel rod 13,57 kW/m Such TVEL provides a relatively high level of combustion of fuel in a known design of the ARC. However, it should be noted that in case of overheating of the fuel cladding, caused by changing conditions of their cooling can occur rethermalization VVER-440, determines its high temperature when operating in the normal operation, a relatively large amount of accumulated heat, and, as a consequence of an accident with blackouts NPP and accident loss of coolant this leads to a considerable heating of the fuel cladding in the first few seconds. Achieved in case of accidents with loss of coolant temperature when using such ARC largely depends on the initial linear thermal loads on the fuel rod. So, when a large leakage of the primary circuit of the reactor VVER-440 fuel rods with a maximum heat load for five seconds have design temperature shell over 900C. At the same time, in the same conditions, fuel load, close to the average, heated to (600-650)C. it Should also be noted that despite gains in topliva.ispolzovanie ~6% (or 6 days in the duration of the cycle) with the same enrichment in a four-year fuel cycle, is obtained by the use of these fuel rods in comparison with the standard fuel elements by increasing water-to-uranium relations in the known Assembly results:

- to increase thermal loads on the fuel rod, to higher odds of non-uniformity power is La the entire temperature range of the heating of the active zone (up to 260C) and a negative coefficient of reactivity on the density of the fluid up to ~150With,

- reduce the stock to the heat transfer crisis,

- deterioration of thermomechanical characteristics of the fuel rod (fuel temperature increase of ~ 220With the beginning of the campaign and ~60With the end of the campaign, the increase in deformation of the shell), although these differences are minor in quantitative terms, but they can be significant in the course of design basis accident and lead to an increase in the number of leaking fuel rods and the release of activity.

Experimental and computational studies show that, from the point of view to prevent the possibility of leaks in the fuel rods in relation to accidents with loss of coolant, the maximum temperature of the shell shall not exceed the level (700-750)C. Therefore, if the active zone of reactor VVER-440 to reduce the maximum linear thermal load by a reasonable reduction of the fuel rod diameter and increase of their quantity in the fuel assemblies (FA) and the ARC, it is possible heating of the shells would not exceed the above limit temperature. This essentially solves the problem volume exacerbated with increasing burnup fuel, when the efficiency of the fuel rods even in normal operating conditions close to the maximum allowable.

From the above it follows that to improve the safety of existing and newly designed nuclear power plants with VVER-440 is a need to develop core fuel container designs of reduced diameter when increased their number in FA and ARC (while maintaining the reactor power and is close to the standard FA and ARC water-uranium relationship of the fuel lattice), which will fundamentally solve the problem of possible leaks in the fuel rods at the initial stage of the accident loss of coolant. In addition, with the development of an advanced active zone of reactor VVER-440, you must make a choice of the main parameters of the conditions of maximum preservation of core design and nuclear power plants, as well as providing acceptable neutron-physical and thermal-hydraulic characteristics that are close to the standard characteristics of the active zone of reactor VVER-440, since the present invention is the development of a new reactor.

This approach leads to some constraints on the choice of the main parameters of the upgraded active zone to the active zone should be the same as in the standard designs of TVs and ARC VVER-440;

- differences in size turnkey and height of the fuel cores modernized Assembly, compared with the standard designs of assemblies of WWER-440, should not exceed 1.5% and 2.5%, respectively;

- the diameter of the rods and their number in the modernized FA and the ARC will ensure the reduction of linear thermal loads in the fuel rods modernized active zone;

- reduction of fuel loading in the modernized FA and the ARC, compared with the standard designs of fuel assemblies and the ARC reactor VVER-440, should not exceed 10%;

- to support project work duration, fuel load reduction of fuel loading in the upgraded Assembly, compared with the standard design of the Assembly must be compensated for by increasing the burnup in the upgraded Assembly relative to the head Assembly;

- increase of the hydraulic friction losses in the modernized Assembly compared with the standard designs of assemblies should not exceed the available resources at the head of the main circulation pump (MCP) of VVER-440;

the number, diameter and placement of organs CPS must be the same as in the standard design of the active zone of reactor VVER-440.

providesuch assemblies of water-cooled power reactor thermal power from 1150 MW to 1,700 MW, with improved characteristics, in particular, increased safety and reliability in the operation of the newly designed and operating reactors that will compensate for the increased cost of the upgraded ARC and get the overall increase in economic efficiency.

The solution of this task, the invention can be obtained by technical results, a reduction of thermal loads of fuel elements, reducing the likelihood of leaks in the fuel cladding, reducing the non-uniformity of energy deposition, expanding the range of control of reactor power and improving fuel consumption by increasing the burnup of nuclear fuel.

These technical results are achieved by the fact that in regulating the fuel Assembly water-cooled power reactor containing absorbing neutrons an extension that is connected with the heat-generating part, containing hexagonal spacer grids, cells which are placed in the beam rod fuel elements from the fuel core of uranium dioxide, enclosed in a shell, characterized in that the spacer sieves the indoor diameters of the shell from 6.0010-3m to 8.0010-3m and 5,0910-3m to 6.7910-3m, respectively, and the mass of uranium dioxide in the beam selected from 69,16 kg to 159,25 kg or spacer grids contain 169 cells for beam containing from 132 to 168 rod fuel elements with outer and inner diameters of the shell from 7,8010-3m to 8,7910-3m and 6,6210-3m to 7.4710-3m, respectively, and the mass of uranium dioxide in the beam selected from 88,67 kg to 149,53 kg

A distinctive feature of the present invention is that the spacer grids contain 217 cells for beam containing from 174 to 216 rod fuel elements with outer and inner diameters of the shell from 6.0010-3m to 8.0010-3m and 5,0910-3m to 6.7910-3m, respectively, and the mass of uranium dioxide in the beam selected from 69,16 kg to 151,25 kg or spacer grids contain 169 cells for beam containing from 132 to 168 rod fuel elements stored is f">10-3m and 6,6210-3m to 7.4710-3m, respectively, and the mass of uranium dioxide in the beam selected from 88,67 kg to 149,53 kg, which characterizes the new concept of the ARC and fuel assemblies of WWER-440 reactor and, accordingly, the active zones of the WWER-440 reactor with improved efficiency, both in normal conditions and in emergency conditions and is conditioned by the following. Since the frame, which enables the mounting beam truss rods in the Assembly, should be similar to the frame of the regular assemblies of WWER-440 reactor, and is water-uranium relationship of the fuel lattice should be close to the value of the standard Assembly (water-to-uranium ratio of the cell standard assemblies to 1.47), the spacer grids are made 217 cells for beam containing from 174 to 216 core rods with the outer and inner diameters of the shell from 6.0010-3m to 8.0010-3m and 5,0910-3m to 6.7910-3m, respectively, and the mass of uranium dioxide in the beam from 69,16 kg to 159,25 kg or in the spacer grids are made 169 cells for beam containing from 132 to 168 //img.russianpatents.com/chr/183.gif">10-3m and 6,6210-3m to 7.4710-3m, respectively, and the mass of uranium dioxide in the beam from 88,67 kg to 149,53 kg, so the average linear load on the fuel rods upgraded the ARC decreases (1,46-2,03) times, while maintaining the rated power of the reactor and providing the neutron-physical and thermal-hydraulic characteristics that are close to the standard characteristics of VVER-440. Or, as the calculations show, you can increase the heat capacity of the active zone, while maintaining the required operational safety of the reactor, the amount to 3.6% of that required to compensate for the increased cost of the upgraded fuel assemblies and the ARC.

It is advisable that the mass of uranium dioxide in the beam, outer and inner diameters of the sheath rod fuel element was 110,36 kg to 136,08 kg, from 7.0010-3m to 7.5010-3m and 5,9410-3m to 6,3610-3m, respectively, for a beam of (204-210) rod fuel elements or mass of uranium dioxide in the beam, outer and inner diameters of the sheath rod fuel element sostav10-3m to 7,1310-3m, respectively, for a beam of (156-162) rod fuel elements.

It is also advisable that the mass of uranium dioxide in the beam, outer and inner diameters of the sheath rod fuel element was 109,89 kg to 135,24 kg, 7.2010-3m to 7.7010-3m and 6,1110-3m to 6,5310-3m, respectively, for a beam of (192-198) rod fuel elements or mass of uranium dioxide in the beam, outer and inner diameters of the sheath rod fuel element was 104,31 kg to 127,80 kg, 8,1010-3to 8.6010-3m and 6,7410-3m to 7.1510-3m, respectively, for a beam of (144-150) rod fuel elements.

In addition, it is advisable that the mass of uranium dioxide in the beam, outer and inner diameters of the sheath rod fuel element was 108,83 kg to 133,73 kg, from 7,4010-3m to 7.9010-3m and 6,2810-3m to 8.7010-3m and? 7.04 baby mortality10-3m to 7.3810-3m, respectively, for a beam of 138 rod fuel elements.

No less appropriate to the mass of uranium dioxide in the beam, outer and inner diameters of the sheath rod fuel element was 116,85 kg to 132,60 kg, from 7.0010-3M. to 7.3010-3m and 5,9410-3m up to 6.1910-3m, respectively, for beam 216-rod fuel elements or mass of uranium dioxide in the beam, outer and inner diameters of the sheath rod fuel element is from 112,98 kg to 126,98 kg, from 7,8010-3m to 8.1010-3m and 6,6210-3m to 6.8710-3m, respectively, for a beam of 168 core fuel elements.

Most appropriate to the mass of uranium dioxide in the beam, narozhny src="https://img.russianpatents.com/chr/183.gif">10-3m to 8.0010-3m and from 6,4510-3m to 6.7910-3m, respectively, for a beam of 174 rod fuel elements or mass of uranium dioxide in the beam, outer and inner diameters of the sheath rod fuel element was 102,83 kg to 117,73 kg, from 8,4010-3m to 8,7910-3m and from 7,1310-3m to 7.4610-3m, respectively, for a beam of 132 core fuel elements.

It is also advisable that the mass of uranium dioxide in the beam, outer and inner diameters of the sheath rod fuel element was 111,79 kg to 129,41 kg, from 7.5010-3m of 7.9010-3m and from 6,3610-3m to 6.7010-3m, respectively, for a beam of 180 rod fuel elements or mass of uranium dioxide in the beam, outer and inner diameters of the sheath rod fuel element was 104,96 kg to 120,33 kg, from 8.3010-3m to 8.70military, for a bunch of 138 rod fuel elements.

It should be emphasized that only the whole set of essential features provides a solution to the problem of the invention and obtaining the above-mentioned new technical results. Indeed, the known fuel rods with an outer diameter of the shell 8,810-3m for ARC reactor VVER-440. However, the choice of only a single value of the outer diameter of the sheath of the fuel element without specifying the ranges of the values of the inner and outer diameters of the sheath of a fuel rod, the appropriate range of fuel weight and their relationship, and without specifying a range of values of the ratio of the height of the fuel core to the length of regulating fuel Assembly (which involves a combination of their constituent specific values) does not allow to implement new technical results. In addition, the combination of the values of the components marked with a pair of ranges of inner and outer diameters of the rods, without the choice of a value for the mass of fuel (uranium dioxide), leads to the possibility of non-compliance allowable change the value of the water-to-uranium relationship of the fuel lattice, and/or heating surface of the fuel rods, which allows to solve (if the condition is NT a longitudinal incision modernized in accordance with the present invention regulates the fuel assemblies for VVER-440, in Fig.2 shows a variant of the cross section of the spacer grid with a bundle of fuel elements, in Fig.3 shows a variant of the longitudinal section of the fuel element for the upgraded ARC reactor VVER-440, Fig.4 shows a cross section of a modernized regulatory fuel Assembly, and Fig.5 presents curves, characterizing the change of the maximum temperature of the shell most energonapryazhennosti staff and upgraded fuel rod used in the described ARC for VVER-440 in the accident with rupture of the pipeline DN 500.

Information confirming the possibility of carrying out the invention.

The described regulating a fuel Assembly contains hex cover - absorbing neutrons an extension 1, is connected with the heat-generating part 2, within which is located a beam 3 of the fuel elements 4 with the casing 5 within which is located the fuel core 6 (see Fig.1 - Fig.3). Fuel elements 4 are installed in a hexagonal spacer grids 7 in hex housing 8. Hexagonal spacer grid 7, made of zirconium alloy, mechanically interconnected by a Central pipe 9 (also manufactured the Fig.2). Depending on the selected number of fuel rods 2 in a bundle, available cell grid spacers 7 can be inserted, for example, cylindrical plungers, burnable absorbers, technological channels, etc., (not shown).

The fuel core 6 may be made with a diameter of from 5.0010-3m to 7.3210-3m and consists of separate tablets 11 with a Central hole 12 in diameter from 0.7910-3m to 1.3510-3m (or solid) or cylindrical rods in length from 6.9010-3m to 12.0010-3m placed in the shell 5, is made with the outer and inner diameters, respectively, from 6.0010-3m to 8,7910-3m and 5,0910-3m to 7.4710-3m, which is a structural bearing element of a fuel rod 4 and to which are attached end part 13 (see Fig.3 and Fig.4). The shell 5 during operation experiences stress due to expansion and swelling of the fuel and also due to the outgassing of fuel, especially in places, which is profiling the form of tablets 11 (or rods), in particular, by performing their ends concave or conical shape of the side surface near the ends (not shown).

As the material of the pills 11 the most appropriate use of pressed and sintered uranium dioxide with an average density (10,4103-10,8103) kg/m3but can also be used oxides of plutonium, thorium and carbides of uranium or a mixture of these fissile materials. The mass of uranium dioxide in the fuel Assembly is 69,16 kg to 159,25 kg

When choosing the thickness of the shell 5 TVEL modernized active young most appropriate to maintain the ratio of shell thickness to the outer diameter of the described fuel rod is the same as in the standard fuel elements of the reactor VVER-440 that maintaining a pressure fill with helium (0,2-0,7) MPa helps to ensure stability of shells of TVEL modernized active zone no less than for regular fuel. In addition, one must also consider the requirement that the radial clearance between the pellets 11 of the fuel core 6 and the shell 5 in the described fuel rods was not less than 0.0510-3M. This condition is due to those who are either active core, and considering all of the above conditions, the shell 5 rod of a fuel rod described the ARC for the upgraded active zone of reactor VVER-440 must have outer and inner diameters (6,0010-3-8,0010-3) m and (5,0910-3-6,7910-3) m, respectively, for beam (174-216) rods or (7,8010-3-8,7910-3) m and (6,6210-3-7,4710-3) m, respectively, for beam (138-168) fuel rods. The fact that the first three of the above conditions, it follows that the relative step h the location of the fuel rods (see Fig.2) must provide water-uranium ratio of the cell 14 (see Fig.4) for the upgraded active zone, close to the water-to-uranium ratio of the cell arrays operating VVER-440. Taking into account all the above conditions, and the results of neutronic, thermal-hydraulic and thermo-mechanical calculations and, above all, the results of the analysis of accidents VVER-440 with leakage of the coolant from the primary circuit, they defined the boundaries of the ranges of the main characteristics of the described ARC for modernized activan from 6.0010-3m to 8.0010-3m;

- the inner diameter of the sheath of the fuel element selected from 5,0910-3m to 6.7910-3m;

- weight of uranium dioxide selected from 69,16 kg to 159,25 kg;

in the spacer grids are made 217 cells, and for beam containing from 132 to 168 Fe:

- the outer diameter of the sheath of a fuel rod is made from 7,8010-3m to 8,7910-3m;

- the inner diameter of the sheath of a fuel rod is made from 6,6210-3m to 7.4710-3m:

- weight of uranium dioxide selected from 88,67 kg to 149,53 kg;

in the spacer grids are made 169 cells.

The implementation of a fuel rod described the ARC beam from 174 to 216 PCs outside diameter less than 6,0010-3m, for example 5,9010-3m, and, therefore, execution of a fuel rod with an inner diameter of the shell is not more 5,0810-3m and the mass of fuel in the fuel assemblies of not more than 69,15 kg leads to failure to comply with conditions relating to the provision of the project the duration of the operation of the fuel load due to reduction of fuel loading in the upgraded ARC, compared with W the new ARC with respect to the standard ARC), and execution of a fuel rod outer diameter greater than 8,0010-3m (for example, 8,1010-3m) and, therefore, execution of a fuel rod with an inner diameter of the shell is not less 6,8010-3m and the mass of fuel in the ARC of not less than 159,26 kg leads to failure to comply with conditions relating to the possible increase of the hydraulic friction losses in the upgraded ARC reactor VVER-440 compared with the standard design of the ARC VVER-440 (the excess of the value of the relative pressure of the reactor coolant pump more than 19%). Performing the same TVEL described the ARC beam from 132 to 168 PCs outside diameter less 7,8010-3m, for example 7,7010-3m, and, therefore, execution of a fuel rod with an inner diameter of the shell is not more 6,6110-3m and the mass of fuel in the ARC of not more than 88,66 kg also leads to failure to comply with conditions relating to the provision of the project the duration of the operation of the fuel load due to reduction of fuel loading in the upgraded ARC, in comparison with the standard design of the ARC VVER-440 (which must be compensated for by increasing the burnup in the upgraded ARC in relation to �//img.russianpatents.com/chr/183.gif">10-3m) and, therefore, execution of a fuel rod with an inner diameter of the shell is not less of 7.4810-3m and the mass of fuel in the ARC of not less than 149,54 kg leads to failure to comply with conditions relating to the possible increase of the hydraulic friction losses in the upgraded ARC reactor VVER-440 compared with the standard design of the ARC VVER-440 (the excess of the value of the relative pressure of the reactor coolant pump more than 10%).

It should be noted that the first four of the above conditions allow you to specify the preferred bounds of the ranges of the main characteristics of the described fuel rod for a modernized active zone of reactor VVER-440, namely:

1. For regulating fuel assemblies with spacer grids containing 217 cells:

the beam contains from 204 to 210 rods,

- the outer diameter of the sheath of the fuel element selected from 7.0010-3m to 7.5010-3m,

- the inner diameter of the sheath of the fuel element selected from 5,9410-3m to 6,3610-3m,

- weight of uranium dioxide in the control of the fuel Assembly is selected from 110,36 kg to 136,08 kg

or

the beam contains 192 to 198 of fuel elements,

- the outer diameter of the sheath of the fuel element within the glasses of a fuel rod is made from 6,1110-3m to 6,5310-3m;

- weight of uranium dioxide in the control of the fuel Assembly is selected from 109,89 kg to 135,24 kg

or

the beam contains 180 to 186 rods,

- the outer diameter of the sheath of a fuel rod is made from 7,4010-3m to 7.9010-3m;

- the inner diameter of the sheath of a fuel rod is made from 6,2810-3m to 6.7010-3m;

- weight of uranium dioxide regulating fuel Assembly selected from 108,83 kg to 133,73 kg

2. For fuel assemblies with spacer grids containing 169 cells:

the beam contains from 156 to 162 of the fuel rods,

- the outer diameter of the sheath of the fuel element selected from 7.9010-3m to 8.4010-3m,

- the inner diameter of the sheath of the fuel element selected from 6,7010-3m to 7,1310-3m,

- weight of uranium dioxide in the control of the fuel Assembly is selected from 107,49 kg to 131,68 kg,

or

the beam contains from 144 to 150 of the fuel rods,

- the outer diameter of the sheath of a fuel rod is made from 8,1010-3m to 8.6010-3m;

- the inner diameter of the sheath of the fuel element the imp is in the control of the fuel Assembly is selected from 104,31 kg to 127,80 kg

or

the beam contains rods 138,

- the outer diameter of the sheath of a fuel rod is made from 8.3010-3m to 8.7010-3m;

- the inner diameter of the sheath of a fuel rod is made from? 7.04 baby mortality10-3m to 7.3810-3m;

- weight of uranium dioxide in the control of the fuel Assembly is selected from 104,96 kg to 120,33 kg

In addition, the first two and last two of the above conditions it follows that for the upgraded active zone of reactor VVER-440 is the most appropriate implementation of the regulatory fuel assemblies with the following characteristics, namely:

1. For regulating fuel assemblies with spacer grids containing 217 cells:

the beam contains rods 216,

- the outer diameter of the sheath of the fuel element selected from 7.0010-3M. to 7.3010-3m;

- the inner diameter of the sheath of the fuel element selected from 5,9410-3m up to 6.1910-3m;

- weight of uranium dioxide in the control of the fuel Assembly is selected from 116,85 kg to 132,60 kg

or

the beam contains rods 174,

- the outer diameter of the sheath of the fuel element selected from 7,6010-3m to 6.7910-3m;

- weight of uranium dioxide regulating fuel Assembly selected from 110,96 kg to 128,29 kg

or

the beam contains 180 fuel elements,

- the outer diameter of the sheath of the fuel element selected from 7.5010-3m to 7.9010-3m;

- the inner diameter of the sheath of the fuel element selected from 6,3610-3m to 6.7010-3m;

- weight of uranium dioxide regulating fuel Assembly selected from 111,79 kg to 129,41 kg

2. For regulating fuel assemblies with spacer grids containing 169 cells:

the beam contains rods 168,

- the outer diameter of the sheath of the fuel element selected from 7,8010-3m to 8.1010-3m;

- the inner diameter of the sheath of the fuel element selected from 6,6210-3m to 6.8710-3m;

- weight of uranium dioxide in the control of the fuel Assembly is selected from 112,85 kg to 126,98 kg

or

the beam contains 132 TVEL,

- the outer diameter of the sheath of the fuel element selected from 8,4010-3m to 8,7910-3m:

- the inner diameter of the sheath of the fuel element selected from 7,13or

the beam contains rods 138,

- the outer diameter of the sheath of the fuel element selected from 8.3010-3m to 8.7010-3m;

- the inner diameter of the sheath of the fuel element selected from? 7.04 baby mortality10-3m to 7.3810-3m;

- weight of uranium dioxide regulating fuel Assembly selected from 104,96 kg to 120,33 kg

The connection of the absorbing neutrons tie-1 and heat-generating part 2 is performed by the docking station 15. Docking station 15 includes a gripping device 16 that communicates with an intermediate rod connected to a travel drive Assembly (not shown).

In the lower part of the regulatory fuel Assembly is provided a hydraulic damper, made in the form of glass 17. When reset, the regulating of the fuel Assembly with emergency protection glass 17 communicates with a return piston, which is located in the tube of the bottom of the active mine area.

Performance analysis and thermomechanical state of the fuel rods helped to clarify some basic design parameters of the fuel rods described the ARC. As shown by computational studies, a significant reduction in heat load on the fuel rod positions the torus PWR design fuel pellets with a Central hole. This decision is caused, on the one hand, a relatively small decrease in the temperature of fuel through the Central hole at low heat loads on the fuel elements and the increased safety margin in relation to the melting of the fuel, and possible technological difficulties in the manufacture of tablets with Central holes less than 1,510-3m

The manufacturing techniques described constructions of fuel elements and regulating fuel assemblies produced by known standard equipment and has no differences from the point of view of production of similar products.

In Fig.5, as an example, presents the curves characterizing the change in the maximum design basis accident (MPA) temperature of the fuel cladding to the maximum load for the staff (the outer diameter of the sheath of standard fuel elements 9,1010-3m) and upgraded (the outer diameter of the sheath of the fuel element described FA 7,0010-3m) of the active zone of reactor VVER-440. From analysis of fuel elements in the specified mode can be seen that the fuel elements in the described Assembly has a significantly lower maximum temperature of the shell. So, for the screens 278With, and for fuel rods with an average load 150C. Such values reduce the temperature of the fuel cladding would fundamentally alter the level of efficiency of the fuel rods and the predicted degree of safety of VVER-440. Primarily, this is due to the strong dependence of the mechanical properties of the sheath material temperature in the T>550With, intensely increasing contribution of heat prociconia reactions in the development of an emergency at temperatures T>700C. Therefore, the transition to a modernized area and, accordingly, reduction of the maximum temperature at MPA 900With below 600With largely eliminates the influence of prociconia response to changes in material properties and geometric dimensions of the fuel claddings.

It should also be noted that the fuel rods described the ARC of a modernized active zone of reactor VVER-440, due to the decrease of the specific heat loads have significantly lower fuel temperature and have a high efficiency due to the reduction of the impact on shell fuel pressure gaseous fission products. Decreased the Balocco from the fuel. This gives reason to believe (design rationale) that the fuel rods described the ARC of a modernized active zone of reactor VVER-440 real achievement average fuel burn-up (55-60) MWday/kg

The efficiency of the fuel elements in the transient operation modes associated with the required maneuvering capacity, due to many factors: the level of thermal loads, the background work, the speed and magnitude of change of capacity, corrosion on the shell side of the fuel core, etc. To avoid depressurization of the fuel rods in the maneuvering mode restrictions are imposed on the speed and range of lifting capacities standard reactor, which leads to economic losses. Valid values “step” lifting power is most sharply decreased with the increase of fuel burnup, and initial linear load. Therefore, the reduction of linear thermal loads of the fuel rods is one of the most effective ways in solving this problem. Reducing the maximum linear thermal loads from 40 kW/m up to 23 kW/m is almost limitless in power change for modernized designs of fuel assemblies. The average linear load of TVEL described Ar>-3m to 8.0010-3m is (6,68-of 6.96) kW/m and (8,95-9,27) kW/m for fuel rods with a diameter of sheath from 7.810-3m to 8,7910-3m (for regular fuel rod with a diameter of 9.110-3m average linear load equal 13,48 kW/m). Therefore, the transition to reduced thermal stresses in the fuel element described FA modernized the active zone of reactor VVER-440 expands the range of the maneuvering capacity of the reactor.

It should also be noted that according to economic calculations to compensate for the increased cost of the upgraded ARC enough or extension of the fuel cycle maximum (25-30) Eph.days, or the increasing power of 3.6%. Assess the potential of the upgraded active zone show that the increase in the length of the fuel cycles of 30 Eph.days achieved during the implementation of the scheme overloads modernized Assembly with a more profound decrease in the leakage of neutrons, which is feasible on the VVER-440 with the increase of thermal reserves in the transition to the reduced diameter of the fuel rods. Thermal-hydraulic calculations modernized the active zone of the reactor VVER-crystals of reduced diameter on the value (up to 15%) significantly more than the requirement (3,6%) to compensate for the increased cost of the upgraded ARC. Thus, the above-described design of the upgraded ARC for VVER-440 allows not only to compensate for the increased cost, but to increase economic efficiency.

Based on the above it can be stated that the transition to a modernized active zone with the described regulating fuel assemblies WWER-440 reactors makes it possible to lower thermal load on the fuel rod in (1,46-2,03) times. Such a significant reduction of linear thermal loads in the fuel rods described the ARC of a modernized active zone of reactor VVER-440 allows:

- to increase the safety of power plants with VVER-440;

- to ensure the possibility of solving the problems associated with the maneuvering capacity of the reactor VVER-440;

- increase the efficiency of the fuel rods under normal operating conditions, which gives grounds to consider the real achievement of the average burnup of the fuel elements (55-60) MWday/kg

It should be noted that the described fuel assemblies can be used not only in the VVER-440 and other pressurized water reactors pressurized water (PWR), boiling-water reactors (BWR) and pressurized heavy water reactors.

Faure is based on absorbing the neutrons an extension, connected with the heat-generating part, containing hexagonal spacer grids, cells which are placed in the beam rod fuel elements from the fuel core of uranium dioxide, enclosed in a shell, characterized in that the spacer grids contain 217 cells for beam containing from 174 to 216 rod fuel elements with outer and inner diameters of the shell from 6.0010-3to 8.0010-3m and 5,0910-3to 6.7910-3m, respectively, and the mass of uranium dioxide in the beam selected from 69,16 to 159,25 kg or spacer grids contain 169 cells for beam containing from 132 to 168 rod fuel elements with outer and inner diameters of the shell from 7,8010-3to 8,7910-3m and 6,6210-3to 7.4710-3m, respectively, and the mass of uranium dioxide in the beam selected from 88,67 to 149,53 kg

2. Regulating a fuel Assembly water-cooled power reactor under item 1, characterized in that the mass of uranium dioxide in the beam, the outer and 83.gif">10-3to 7.5010-3m and 5,9410-3to 6,3610-3m, respectively, for a bunch of (204-210) rod fuel elements or mass of uranium dioxide in the beam, outer and inner diameters of the sheath rod fuel element is from 107,49 to 131,68 kg, from 7.9010-3to 8.4010-3m and from 6,7010-3before 7,1310-3m, respectively, for a bunch of (156-162) rod fuel elements.

3. Regulating a fuel Assembly water-cooled power reactor under item 1, characterized in that the mass of uranium dioxide in the beam, outer and inner diameters of the sheath rod fuel element is from 109,89 to 135,24 kg, 7.2010-3to 7.7010-3m and 6,1110-3to 6,5310-3m, respectively, for a bunch of (192-198) rod fuel elements or mass of uranium dioxide in the beam, outer and inner diameters of the sheath rod fuel element is from 104,31 to 127,80 10-3to 7.1510-3m, respectively, for a bunch of (144-150) rod fuel elements.

4. Regulating a fuel Assembly water-cooled power reactor under item 1, characterized in that the mass of uranium dioxide in the beam, outer and inner diameters of the sheath rod fuel element is from 108,83 to 133,73 kg, from 7,4010-3to 7.9010-3m and 6,2810-3to 6.7010-3m, respectively, for a bunch of (180-186) rod fuel elements or mass of uranium dioxide in the beam, outer and inner diameters of the sheath rod fuel element is from 104,96 to 120,33 kg, from 8.3010-3to 8.7010-3m and? 7.04 baby mortality10-3to 7.3810-3m, respectively, for a beam of 138 rod fuel elements.

5. Regulating a fuel Assembly water-cooled power reactor under item 1, characterized in that the mass of uranium dioxide in the beam, outer and inner diameters of the sheath rod fuel element composition src="https://img.russianpatents.com/chr/183.gif">10-3up to 6.1910-3m, respectively, for beam 216-rod fuel elements or mass of uranium dioxide in the beam, outer and inner diameters of the sheath rod fuel element is from 112,98 to 126,98 kg, from 7,8010-3to 8.1010-3m and 6,6210-3to 6.8710-3m, respectively, for a beam of 168 core fuel elements.

6. Regulating a fuel Assembly water-cooled power reactor under item 1, characterized in that the mass of uranium dioxide in the beam, outer and inner diameters of the sheath rod fuel element is from 110,96 to 128,29 kg, 7,6010-3to 8.0010-3m and from 6,4510-3to 6.7910-3m, respectively, for a beam of 174 rod fuel elements or mass of uranium dioxide in the beam, outer and inner diameters of the sheath rod fuel element is from 102,83 to 117,73 kg, from 8,4010-3to 8,7910-3m and from 7,137. Regulating a fuel Assembly water-cooled power reactor under item 1 and/or 4, characterized in that the mass of uranium dioxide in the beam, outer and inner diameters of the sheath rod fuel element is from 111,79 to 129,41 kg, from 7.5010-3to 7.9010-3m and from 6,3610-3to 6.7010-3m, respectively, for a beam of 180 rod fuel elements or mass of uranium dioxide in the beam, outer and inner diameters of the sheath rod fuel element is from 104,96 to 120,33 kg, from 8.3010-3to 8.7010-3m and? 7.04 baby mortality10-3to 7.3810-3m, respectively, for a beam of 138 rod fuel elements.

 

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