Control method of reactor core and reactor rod group

Abstract

The embodiment of the invention provides a reactor core and a control method of a reactor rod group, the reactor core comprises a first rod group, a second rod group, a third rod group and a control unit, and the control unit is electrically connected with the first rod group, the second rod group and the third rod group. The arrangement of the reactor rod groups is optimized, the first rod group adjusts the axial power offset of the reactor, the second rod group is controlled to intervene under the condition that the output power of the reactor is smaller than the preset power, and power adjustment is carried out through the second rod group so as to compensate reactive changes caused by power feedback; and when the output power of the reactor is larger than or equal to the preset power, the second rod group is controlled to stop intervention, and reactive changes caused by power feedback, moderator temperature and xenon oscillation are compensated through the third rod group. And the insertion depth of the first rod group is reduced, so that the disturbance of the reactor rod group on the reactivity of the reactor core is reduced, the safety margin of the reactor is improved, and the safety and the operation flexibility of the nuclear power station are improved.

Description

Technical Field

[0001] The present invention relates to the field of nuclear power technology, and in particular to a control method for a reactor core and a reactor rod group. Background Art

[0002] With the development of nuclear power technology and the connection of other intermittent power sources (such as hydropower, wind power or photovoltaic power), nuclear power plants need to participate more in grid peak load regulation. Therefore, the requirements for the load tracking operation capability of nuclear power plants are getting higher and higher.

[0003] At present, the operation control modes of nuclear power plants mainly include: G mode and mechanical compensation control (MSHIM) mode. In G mode, it includes a power regulation system and a temperature regulation system. The open-loop regulation loop of the power regulation system sequentially adjusts the power rod group (G1, G2, N1, N2) to track the power of the steam turbine generator set. The temperature regulation system controls the average temperature of the reactor by adjusting the temperature rod group (R rod group) to compensate for the residual reactivity changes caused by weak (moderator temperature, xenon, etc.) reactivity changes or inaccurate setting of the power rod group, and to limit the axial power deviation. The movement of the R rod group needs to be limited to the preset adjustment band to avoid excessive axial power distortion. Once the movement of the R rod group exceeds the preset adjustment band, the operator adjusts the boron concentration to return the R rod group to the preset adjustment band. However, frequent adjustment of the boron concentration will cause the amount of wastewater to increase exponentially. In the MSHIM mode, two independent groups of control rods are used for reactivity control and axial power offset control respectively. The rod group used to control power regulation can be automatically adjusted in any power range and is not affected by the axial power distribution. At the same time, the influence of power on axial power offset can be independently adjusted by the rod group used to control axial power offset. The role of adjusting boron concentration is only to compensate for the slow change of reactivity caused by fuel consumption, thereby reducing the generation of nuclear waste water.

[0004] However, the rod group used to control the axial power deviation during load following in the MSHIM mode is inserted too deep into the core, which will lead to a reduction in the safety margin. Summary of the invention

[0005] The embodiment of the present invention provides a control method for a core and a reactor rod group, so as to solve the problem in the prior art that the rod group for controlling axial power deviation is inserted into the core too deeply, resulting in a low safety margin of the reactor.

[0006] An embodiment of the present invention provides a core, including:

[0007] a first rod group, the first rod group being used to adjust the axial power offset of the reactor;

[0008] a second rod group, the second rod group being used to compensate for a reactivity change caused by power feedback;

[0009] a third rod group, the third rod group being used to compensate for the change in the reactivity caused by the moderator temperature and the xenon oscillation;

[0010] a control unit, the control unit being electrically connected to the first rod group, the second rod group and the third rod group respectively;

[0011] Wherein, the control unit is used for:

[0012] When the output power of the reactor is greater than or equal to a preset power, the number of steps of movement of the third rod group is adjusted to compensate for the reactivity change caused by power feedback, moderator temperature and xenon oscillation, and the number of steps of movement of the first rod group is adjusted to compensate for the axial power deviation of the reactor caused by the reactivity change and the movement of the third rod group;

[0013] When the output power of the reactor is less than the preset power, the number of steps of movement of the second rod group and the third rod group is adjusted to compensate for the reactivity change caused by power feedback, moderator temperature and xenon oscillation, and the number of steps of movement of the first rod group is adjusted to compensate for the axial power deviation of the reactor caused by the reactivity change and the movement of the second rod group and the third rod group.

[0014] Optionally, the preset power ranges from 80% to 90% of the full power of the reactor.

[0015] Optionally, when the load following operation is reduced in power and the output power of the reactor is greater than or equal to a preset power, the number of steps of movement of the third rod group is increased so that the third rod group moves in a direction of inserting into the core, and the number of steps of movement of the first rod group is adjusted so that the axial power deviation of the reactor is controlled within a first preset range;

[0016] In the case of load following operation power reduction, when the output power of the reactor is less than the preset power, the number of steps of movement of the second rod group and the third rod group is increased so that the second rod group and the third rod group move in the direction of inserting into the core, and the number of steps of movement of the first rod group is adjusted so that the axial power deviation of the reactor is controlled within a second preset range; wherein, in the entire load following operation power reduction process, the number of steps of movement of the first rod group ranges from 0 to 41 steps;

[0017] When the load following operation is performed and the output power of the reactor is less than the preset power, the number of steps of movement of the second rod group and the third rod group is reduced so that the second rod group and the third rod group move in a direction of withdrawing from the core, and the number of steps of movement of the first rod group is adjusted so that the axial power deviation of the reactor is controlled within a third preset range;

[0018] When the load following operation is performed to increase the power and the output power of the reactor is greater than or equal to the preset power, the number of steps of movement of the third rod group is reduced so that the third rod group moves in the direction of withdrawing the core, and the number of steps of movement of the first rod group is adjusted so that the axial power offset of the reactor is controlled within a fourth preset range; wherein, during the entire load following operation to increase the power, the number of steps of movement of the first rod group ranges from 41 steps to 0 steps.

[0019] Optionally, the first rod group is a black rod group, the second rod group is the black rod group, and the third rod group is a gray rod group, and the loading amount of absorber material in the black rod group is higher than the loading amount of absorber material in the gray rod group.

[0020] Optionally, the second rod group includes a first power regulating rod group, a second power regulating rod group and a third power regulating rod group, and the first power regulating rod group, the second power regulating rod group and the third power regulating rod group operate in sequence in an overlapping manner to adjust the output power of the reactor to different amplitudes during the load tracking process.

[0021] Optionally, the third rod group includes a first temperature regulating rod group, a second temperature regulating rod group, a third temperature regulating rod group and a fourth temperature regulating rod group, and the first temperature regulating rod group, the second temperature regulating rod group, the third temperature regulating rod group and the fourth temperature regulating rod group operate in step, so as to adjust the output power and the temperature of the reactor to different extents during the load tracking process.

[0022] Optionally, a fourth rod group electrically connected to the control unit is further included, and the fourth rod group is used to provide a safe shutdown control capability.

[0023] An embodiment of the present invention further provides a control method for a reactor rod group, which is applied to the above-mentioned core, and the method includes:

[0024] acquiring the output power of the reactor upon receiving the target instruction, wherein the target instruction includes controlling the output power of the reactor to reach the target power;

[0025] When the output power of the reactor is greater than or equal to a preset power, the number of steps of movement of the third rod group is adjusted to compensate for the reactivity change caused by power feedback, moderator temperature and xenon oscillation, and the number of steps of movement of the first rod group is adjusted to compensate for the axial power deviation of the reactor caused by the reactivity change and the movement of the third rod group;

[0026] When the output power of the reactor is less than the preset power, the number of steps of movement of the second rod group and the third rod group is adjusted to compensate for the reactivity change caused by power feedback, moderator temperature and xenon oscillation, and the number of steps of movement of the first rod group is adjusted to compensate for the axial power deviation of the reactor caused by the reactivity change and the movement of the second rod group and the third rod group.

[0027] Optionally, when the output power of the reactor is greater than or equal to a preset power, adjusting the number of steps of movement of the third rod group to compensate for the reactivity change caused by power feedback, moderator temperature and xenon oscillation, and adjusting the number of steps of movement of the first rod group to compensate for the reactor axial power deviation caused by the reactivity change and the movement of the third rod group, comprises:

[0028] When the target power is greater than or equal to the preset power and the output power of the reactor is greater than the target power, the number of steps of the movement of the third rod group is controlled to increase so as to compensate for the reactivity change caused by power feedback, moderator temperature and xenon oscillation, and the number of steps of the movement of the first rod group is controlled to increase so as to compensate for the axial power deviation of the reactor caused by the reactivity change and the movement of the third rod group, so that the output power of the reactor is adjusted down to the target power;

[0029] When the output power of the reactor is greater than or equal to the preset power and the target power is greater than the output power of the reactor, the number of steps of the movement of the third rod group is controlled to decrease so as to compensate for the reactivity change caused by power feedback, moderator temperature and xenon oscillation, and the number of steps of the movement of the first rod group is controlled to decrease so as to compensate for the axial power deviation of the reactor caused by the reactivity change and the movement of the third rod group, so that the output power of the reactor is adjusted upward to the target power;

[0030] When the target power is less than the preset power and the output power of the reactor is greater than the preset power, the number of steps of the third rod group is controlled to increase so as to compensate for the reactivity change caused by power feedback, moderator temperature and xenon oscillation, and the number of steps of the first rod group is controlled to increase so as to compensate for the reactivity change and the axial power deviation of the reactor caused by the movement of the third rod group, so that the output power of the reactor is adjusted down to the preset power; then, the second rod group is controlled to intervene, and the number of steps of the second rod group and the third rod group is controlled to increase so as to compensate for the reactivity change caused by power feedback, moderator temperature and xenon oscillation, and the number of steps of the first rod group is controlled to decrease so as to compensate for the reactivity change and the axial power deviation of the reactor caused by the movement of the second rod group and the third rod group, so that the output power of the reactor is adjusted down from the preset power to the target power.

[0031] Optionally, when the output power of the reactor is less than the preset power, adjusting the number of steps of movement of the second rod group and the third rod group to compensate for the reactivity change caused by power feedback, moderator temperature and xenon oscillation, and adjusting the number of steps of movement of the first rod group to compensate for the reactor axial power deviation caused by the reactivity change and the movement of the second rod group and the third rod group, comprising:

[0032] When the target power is less than or equal to the preset power and the output power of the reactor is less than the target power, the number of steps of the movement of the second rod group and the third rod group is controlled to decrease so as to compensate for the reactivity change caused by power feedback, moderator temperature and xenon oscillation, and the number of steps of the movement of the first rod group is controlled to increase so as to compensate for the axial power deviation of the reactor caused by the reactivity change and the movement of the second rod group and the third rod group, so that the output power of the reactor is increased to the target power;

[0033] When the output power of the reactor is less than or equal to the preset power and the target power is less than the output power of the reactor, the number of steps of the movement of the second rod group and the third rod group is controlled to increase so as to compensate for the reactivity change caused by power feedback, moderator temperature and xenon oscillation, and the number of steps of the movement of the first rod group is controlled to decrease so as to compensate for the axial power deviation of the reactor caused by the reactivity change and the movement of the second rod group and the third rod group, so that the output power of the reactor is adjusted down to the target power;

[0034] In the case that the target power is greater than the preset power and the output power of the reactor is less than the preset power, the number of steps of the movement of the second rod group and the third rod group is controlled to decrease so as to compensate for the reactivity change caused by power feedback, moderator temperature and xenon oscillation, and the number of steps of the movement of the first rod group is controlled to increase so as to compensate for the reactivity change and the axial power deviation of the reactor caused by the movement of the second rod group and the third rod group, so that the output power of the reactor is increased to the preset power; then, the second rod group is controlled to stop intervening, and the number of steps of the movement of the third rod group is controlled to decrease so as to compensate for the reactivity change caused by power feedback, moderator temperature and xenon oscillation, and the number of steps of the movement of the first rod group is controlled to decrease so as to compensate for the axial power deviation of the reactor caused by the reactivity change and the movement of the third rod group, so that the output power of the reactor is increased from the preset power to the target power.

[0035] In the embodiment of the present invention, by optimizing the arrangement of the reactor rod group, the first rod group adjusts the axial power offset of the reactor, and when the output power of the reactor is less than the preset power, the second rod group is controlled to intervene, and the power is adjusted by the second rod group to compensate for the reactivity change caused by power feedback; when the output power of the reactor is greater than or equal to the preset power, the second rod group is controlled to stop intervening, and the reactivity change caused by power feedback, moderator temperature and xenon oscillation is compensated by the third rod group; at the same time, the axial power offset of the reactor is compensated by the first rod group, so that the reactor has the ability of non-boron load tracking, and the insertion depth of the first rod group is reduced, thereby reducing the disturbance of the reactor rod group to the core reactivity, improving the safety margin of the reactor, and improving the safety and operation flexibility of the nuclear power plant. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative labor.

[0037] Figure 1 is a graph showing the relationship between the reactivity and AO introduced by the insertion of a reactor rod group provided in an embodiment of the present invention;

[0038] Figure 2 It is a schematic diagram of a quarter structure of a core provided by an embodiment of the present invention;

[0039] Figure 3 This is a schematic diagram of 1 / 4 loading of a core provided by an embodiment of the present invention;

[0040] Figure 4 is a rod position diagram of the R rod group and the G rod group that varies with time provided by the comparative example of the present invention;

[0041] Figure 5 It is a graph of AO changing with time provided by the comparative example of the present invention;

[0042] Figure 6 It is a graph of FQ and FΔH changing with time provided by the comparative example of the present invention;

[0043] Figure 7 is a diagram of AO control during daily load tracking provided by an embodiment of the present invention;

[0044] Figure 8 is a diagram showing the change of the rod position of the R rod group over time during the daily load tracking process provided by an embodiment of the present invention;

[0045] Fig. 9is a diagram showing the change of the G-rod group rod position over time during the daily load tracking process provided by an embodiment of the present invention;

[0046] Fig.10 is a curve diagram of FQ and FΔH changes during daily load tracking provided by an embodiment of the present invention;

[0047] Fig.11 It is a flow chart of a control method of a reactor rod group provided by an embodiment of the present invention. DETAILED DESCRIPTION

[0048] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0049] The terms "first", "second", etc. in the specification and claims of the present invention are used to distinguish similar objects, and are not used to describe a specific order or sequence. It should be understood that the structures used in this way can be interchanged where appropriate, so that the embodiments of the present invention can be implemented in an order other than those illustrated or described herein, and the objects distinguished by "first", "second", etc. are generally of the same type, and the number of objects is not limited. For example, the first object can be one or more. In addition, "and / or" in the specification and claims represents at least one of the connected objects, and the character " / " generally indicates that the objects associated with each other are in an "or" relationship.

[0050] An embodiment of the present invention provides a core, comprising:

[0051] a first rod group, the first rod group being used to adjust the axial power offset of the reactor;

[0052] a second rod group, the second rod group being used to compensate for a reactivity change caused by power feedback;

[0053] a third rod group, the third rod group being used to compensate for reactivity changes caused by power feedback, moderator temperature, and xenon oscillation;

[0054] a control unit, the control unit being electrically connected to the first rod group, the second rod group and the third rod group respectively;

[0055] Wherein, the control unit is used for:

[0056] When the output power of the reactor is greater than or equal to a preset power, the number of steps of movement of the third rod group is adjusted to compensate for the reactivity change caused by power feedback, moderator temperature and xenon oscillation, and the number of steps of movement of the first rod group is adjusted to compensate for the axial power deviation of the reactor caused by the reactivity change and the movement of the third rod group;

[0057] When the output power of the reactor is less than the preset power, the number of steps of movement of the second rod group and the third rod group is adjusted to compensate for the reactivity change caused by power feedback, moderator temperature and xenon oscillation, and the number of steps of movement of the first rod group is adjusted to compensate for the axial power deviation of the reactor caused by the reactivity change and the movement of the second rod group and the third rod group.

[0058] Changes in nuclear power plant power will cause changes in fuel and moderator temperature, xenon concentration and xenon distribution, and axial power distribution. Therefore, nuclear power plants should adopt reasonable operation control modes to compensate for changes in core reactivity and control the core axial power distribution within a reasonable range. Among them, nuclear power plants can be 10,000 kilowatts to 2 million kilowatts (electric power) level. The first rod group can be recorded as the R rod group, which is used to adjust the core axial flux offset to the required target value during the power change process; the second rod group plays the role of the power adjustment rod group during the power adjustment process, which is used to compensate for the reactivity changes caused by the power feedback band; the third rod group plays the role of the temperature adjustment rod group during the power adjustment process, which is mainly used to compensate for the reactivity changes caused by xenon oscillation, and can also compensate for the reactivity changes caused by power feedback.

[0059] In one example, the third rod group can be made of a lower-value material as the neutron absorber of the gray rod group inserted first, so as to reduce the value of the control rods of the gray rod group, while the first rod group and the second rod group can be a higher-value black rod group, and the loading amount of the absorber material in the black rod group is higher than that in the gray rod group. And the first rod group is inserted into the core at a shallower depth, in other words, the number of steps of the first rod group moving in the direction of insertion into the core is smaller, so as to reduce the disturbance caused to the core reactivity.

[0060] In one example, the second rod group includes a first power regulating rod group (denoted as N1), a second power regulating rod group (denoted as N2) and a third power regulating rod group (denoted as N3), and the first power regulating rod group, the second power regulating rod group and the third power regulating rod group are sequentially stepped to adjust the output power of the reactor with different amplitudes during load following operation. The first power regulating rod group, the second power regulating rod group and the third power regulating rod group are sequentially stepped to reduce the influence of the second rod group on the axial power deviation when introducing reactivity, and increase the safety margin of the reactor.

[0061] In one example, the third rod group includes a first temperature regulating rod group (denoted as G1), a second temperature regulating rod group (denoted as G2), a third temperature regulating rod group (denoted as G3) and a fourth temperature regulating rod group (denoted as G4), and the first temperature regulating rod group, the second temperature regulating rod group, the third temperature regulating rod group and the fourth temperature regulating rod group are operated in step, and are used to adjust the output power and the temperature of the reactor with different amplitudes during load tracking operation. The first temperature regulating rod group, the second temperature regulating rod group, the third temperature regulating rod group and the fourth temperature regulating rod group are operated in step, which can reduce the influence of the third rod group on the axial power deviation when introducing reactivity, and increase the safety margin of the reactor.

[0062] In this way, by subdividing the control rod group into a power regulating rod group (open-loop control, rod position corresponds to power level one by one, compensating for most of the power feedback) and a temperature regulating rod group (closed-loop control, adjusting the average coolant temperature, compensating for the remaining power feedback and reactivity changes caused by xenon poisoning), for the temperature regulating rod group, when reactivity is introduced after stepping, the impact on the axial power offset should be small; and for the power regulating rod group, when reactivity is introduced after stepping, the impact on the axial power offset and the impact of power change on the axial power offset should be small after offsetting each other, thereby increasing the safety margin of the reactor.

[0063] like Figure 1 As shown, the R rod group is a black rod group. The reactivity value introduced in the initial stage is very large, and the impact on the axial power offset (AO) is very obvious; the gray rod value is smaller, but from the initial insertion, the impact of the introduction of unit reactivity value on the axial power offset (i.e., the slope in the figure) is also large. In the figure, the horizontal axis is reactivity, and the vertical axis is the change in axial power offset. In the case of no overlapping setting during the insertion of each rod group, each rod group is first inserted into the upper part of the core and then into the lower part of the core, resulting in a very large fluctuation in the axial power offset shown in the figure, which is not conducive to core control. The gray rod group has little effect on the axial power offset during the insertion process (overlapping part), which is suitable for compensating xenon oscillation; the impact of the black rod group on the axial power offset during the insertion process and the impact of power change on the axial power offset are both large, which can offset each other to reduce the need to move the R rod group (i.e., the first rod group), and avoid the R rod group being inserted too deep or all pulled out, which cannot meet the axial power offset control requirements. The stepped portion of the gray rod group is used to compensate for the reactivity required for xenon oscillations, fuel consumption and moderator temperature changes, and will be partially inserted at full power; the power adjustment rod group is composed entirely of black rods, which are used to compensate for the reactivity required for power changes. In order to avoid the adverse effects of black rod insertion on power distribution at high power and the axial power offset being too negative, resulting in the inability of all R rod groups to meet the axial power offset control requirements, the power point at which the power rods start to be inserted can be appropriately lowered, and the power feedback between full power and this power point is compensated by the temperature adjustment rod group.

[0064] The preset power range is 80% to 90% of the full power of the reactor. For a specific fuel management scheme, an exemplary description is given by taking the preset power of 85% of the full power of the reactor as an example, and calculation and analysis under three typical burnup conditions of BLX, MOL, and 85% EOL are carried out. The optimal step data of the reactor rod group can be 95 steps. It should be understood that the preset power range is 80% to 90% of the full power of the reactor, which can also achieve the same technical effect.

[0065] Among them, it also includes a fourth rod group electrically connected to the control unit. The fourth rod group may include a first shutdown rod group (denoted as SA), a second shutdown rod group (denoted as SB), a third shutdown rod group (denoted as SC) and a fourth shutdown rod group (denoted as SD). The fourth rod group is used to provide a safe shutdown control capability to enhance the safety of the reactor.

[0066] In the MSHIM mode, there are two independent control rods: the M rod group and the AO rod group. The M rod group is mainly used to compensate for the reactivity lost (or released) due to the burnup of fuel and burnable poisons, and to compensate for power loss and xenon oscillation during power adjustment. The M rod group has a total of 6 groups of control rods, namely MA, MB, MC, MD, M1, and M2, among which MA, MB, MC, and MD are gray rods containing tungsten; M1 and M2 are black rods of silver indium cadmium. There are two insertion orders for M rods, namely MA-MB-MC-MD-M1-M2 and MD-MC-MB-MA-M1-M2, in order to reduce the burnup shadow caused by rod insertion and reduce the value difference between gray rods. The AO rod group is a control rod group specifically used to control the axial power distribution of the reactor. The AO rod group has sufficient reactivity value and sensitivity to AO, and can maintain an almost constant axial power offset (AO) in all power operating ranges.

[0067] Considering that the safety margin is reduced due to the excessive insertion of the AO rod group. In the embodiment of the present invention, when the load following operation is reduced in power and the output power of the reactor is greater than or equal to the preset power, the number of steps of the third rod group movement is increased so that the third rod group moves in the direction of insertion into the core, and the number of steps of the first rod group movement is adjusted so that the reactor axial power offset is controlled within a first preset range;

[0068] In the case of load following operation power reduction, when the output power of the reactor is less than the preset power, the number of steps of movement of the second rod group and the third rod group is increased so that the second rod group and the third rod group move in the direction of inserting into the core, and the number of steps of movement of the first rod group is adjusted so that the axial power deviation of the reactor is controlled within a second preset range; wherein, in the entire load following operation power reduction process, the number of steps of movement of the first rod group ranges from 0 to 41 steps;

[0069] When the load following operation is performed and the output power of the reactor is less than the preset power, the number of steps of movement of the second rod group and the third rod group is reduced so that the second rod group and the third rod group move in a direction of withdrawing from the core, and the number of steps of movement of the first rod group is adjusted so that the axial power deviation of the reactor is controlled within a third preset range;

[0070] When the load following operation is performed to increase the power and the output power of the reactor is greater than or equal to the preset power, the number of steps of movement of the third rod group is reduced so that the third rod group moves in the direction of withdrawing the core, and the number of steps of movement of the first rod group is adjusted so that the axial power offset of the reactor is controlled within a fourth preset range; wherein, during the entire load following operation to increase the power, the number of steps of movement of the first rod group ranges from 41 steps to 0 steps.

[0071] It should be noted that the reference for controlling the axial power offset of the reactor is different under different output powers, so the preset ranges for controlling the axial power offset of the reactor under different output powers may be different, that is, the first preset range, the second preset range, the third preset range and the fourth preset range may be different. For example, when the reactor output power is 80%, the reference for the axial power offset of the reactor may be ΔI, and the first preset range may be ΔI±3%.

[0072] Specifically, in this embodiment, the arrangement of the core control rod groups of the 177 fuel assemblies is optimized and designed, and a total of 69 bundles of reactor rod groups are arranged in the core, among which the first rod group (i.e., the R rod group) responsible for regulating the axial power offset of the reactor adopts silver indium cadmium absorbers, and a total of 9 bundles of R rods are used to control the core AO. The second rod group (i.e., N1, N2, and N3) adopts silver indium cadmium absorbers, and acts as a power regulation rod group in the power regulation process below 85% FP, which is used to compensate for the reactivity changes caused by power feedback. Among them, the N1 rod group can be 4 groups, the N2 rod group can be 8 groups, and the N3 rod group can be 8 groups. The third rod group (i.e., G1, G2, G3, and G4) can be a temperature regulation rod group, 4 groups each, using low-loaded silver indium cadmium absorbers or stainless steel plus silver indium cadmium as absorbers, mainly used to compensate for the reactivity changes caused by xenon oscillations. The first rod group, the second rod group, and the third rod group are arranged behind the corresponding fuel assemblies, and the schematic diagram of the 1 / 4 structure of the core is as shown in the figure. Figure 2As shown. Among them, more gray rod groups are set in the third rod group, and the power rod does not move when only compensating the core xenon poisoning reactivity changes, and AO is easy to control; the first rod group is inserted shallowly, and the AO control ability of the core is also strong, which is conducive to strengthening the load tracking ability without boron adjustment. In this way, by optimizing the arrangement of the reactor rod group, the first rod group adjusts the reactor axial power offset, controls the second rod group to intervene when the output power of the reactor is less than the preset power, and adjusts the power through the second rod group to compensate for the reactivity change caused by power feedback; when the output power of the reactor is greater than or equal to the preset power, the second rod group is controlled to stop intervening, and the third rod group is used to compensate for the reactivity change caused by power feedback, moderator temperature and xenon oscillation; at the same time, the reactor axial power offset is compensated by the first rod group, so that the reactor has the load tracking ability without boron adjustment, and the insertion depth of the first rod group is reduced (the number of steps of the first rod group can be controlled between 0 and 41 steps), thereby reducing the disturbance of the reactor rod group to the core reactivity, improving the safety margin of the reactor, and improving the safety and operation flexibility of the nuclear power plant.

[0073] The core provided by the present invention is further described below based on comparative examples and embodiments.

[0074] Comparative Example:

[0075] The comparative example is a balanced cycle core, and the core parameters are:

[0076] The core thermal power is 3210MWth. The core consists of 177 groups of 4.45% enrichment components with an active zone length of 365.76cm. The components adopt an axial partition design. The schematic diagram of 1 / 4 loading of the core is as follows: Figure 3 The reactor consists of 177 improved full M5 AFA3G fuel assemblies, the core active section height (cold state) is 365.76cm, the equivalent diameter is 323cm, the core height-to-diameter ratio is 1.133, and the average linear power density is 182.9W / cm. The reactor core rated thermal power is 3210MW, the reactor operating pressure is 15.5MPa, and the total reactor coolant flow (best estimate) is 76350m 3 / h.

[0077] The reactor operation mode is the non-boron load tracking mode. The reactor is equipped with 69 bundles of reactor rod groups, which are divided into control rod groups and shutdown rod groups (SA, SB, SC, SD). The control rod groups are further divided into axial power offset control rod groups (R rod groups), power adjustment rod groups (N1, N2 and N3) and temperature adjustment rod groups (G1, G2, G3 and G4). The balance cycle adopts an 18-month refueling plan. 72 new assemblies are used, and the enrichment of U-235 in the UO2 fuel rods in the new assemblies is 4.45% and 4.95%.

[0078] The load tracking capability is calculated under a typical daily load variation of 12-3-6-3 (50% FP): the initial fuel consumption state is 17000MWd / tU (85% EOL); the boron concentration is 255.35ppm; the rod position R=210 steps, G4=5 steps, G3=135 steps, G2=225 steps, G1=225 steps; AO=2.58±1% steps; and a constant AO control simulation is performed.

[0079] First, the conventional load-following reactor control mode (MSHIM) without boron regulation was simulated, that is, G1~G4 and N1~N3 rod groups participate in the reactivity closed-loop control together, and the R rod group controls AO. The results of the MSHIM model simulation are shown in Figure 2. Figure 4 As shown in the figure, the lowest rod position of the R rod group is 125 steps, and that of the G rod group is -220 steps. If the R rod group is inserted too deep, it will lead to a more serious burnup shadow effect and a larger hot spot factor FQ. Figure 5 It can be seen that the MSHIM mode can well control the AO within the target band; Figure 6 It can also be seen that the maximum FQ is 2.119.

[0080] Example:

[0081] The embodiment is modified as follows based on the comparative example: a newly designed non-boron load tracking core control mode is simulated, that is, the reactor rod group is divided into a first rod group (i.e., R rod group), a second rod group (i.e., power adjustment rod group (N1, N2 and N3)) and a third rod group (i.e., temperature adjustment rod group (G1, G2, G3 and G4)), wherein the second rod group and the third rod group are set separately. According to the trial calculation, the starting power point of the second rod group insertion is determined to be 85% FP; then the N1 to N3 rod positions corresponding to the power below 85% FP are determined; finally, a load tracking simulation is performed for 2 days and 48 hours.

[0082] The core loading diagram of the embodiment is the same as that of the comparative example. Figure 3 As shown; the difference is that the second rod group participates in power regulation under 85% FP.

[0083] In the traditional MSHIM mode, the adjustment rod group needs to be inserted very deep to compensate for the power feedback when reducing the power. Figure 1 It can be seen that the insertion of the regulating rod group after stepping is not sensitive to the influence of AO, which will cause the AO to be obviously positive due to power reduction, and then the first rod group needs to be inserted too deep to compensate (see Figure 4 ). Therefore, a new rod insertion strategy is designed, that is, during the period of 100% to 85% FP, the third rod group is still used to control the reactivity; during the power reduction process below 85% FP, the second rod group compensates for the power feedback (which can be open-loop control), and the third rod group compensates for the change in xenon poisoning reactivity. The rod positions of the second rod group corresponding to the power below 85% shown in Table 1 are calculated.

[0084] Table 1

[0085]

[0086] A simulation of 12-3-6-3, 50% power step for 2 days and 48 hours was performed. Figure 7 It can be seen that the core provided by the present invention can well control AO within the target range. Figure 8 As can be seen, the lowest stick position of the first stick group is 184 steps, and the third stick group is -203 steps. Figure 8 and Fig. 9 The changes of the third rod group and the second rod group over time during the daily load tracking process are given. Fig.10 It can be seen that the maximum FQ is 1.965. The smaller FQ of the embodiment is related to the shallower insertion depth of the first rod and the better AO control. In this way, by optimizing the arrangement of the reactor rod group, the first rod group adjusts the reactor axial power offset, controls the second rod group to intervene when the output power of the reactor is less than the preset power, and performs power adjustment through the second rod group to compensate for the reactivity changes caused by power feedback; when the output power of the reactor is greater than or equal to the preset power, controls the second rod group to stop intervening, and compensates for the reactivity changes caused by power feedback, moderator temperature and xenon oscillation through the third rod group; at the same time, the reactor axial power offset is compensated by the first rod group, so that the reactor has the ability to track the boron load without adjustment, and the insertion depth of the first rod group is reduced, thereby reducing the disturbance of the reactor rod group to the core reactivity, improving the safety margin of the reactor, and improving the safety and operation flexibility of the nuclear power plant.

[0087] See also Fig.11 , Fig.11 FIG. 1 is a flow chart of a control method for a reactor rod group provided by an embodiment of the present invention. Fig.11 As shown, an embodiment of the present invention further provides a control method for a reactor rod group, which is applied to the above-mentioned core, and the method includes:

[0088] acquiring the output power of the reactor upon receiving the target instruction, wherein the target instruction includes controlling the output power of the reactor to reach the target power;

[0089] When the output power of the reactor is greater than or equal to a preset power, the number of steps of movement of the third rod group is adjusted to compensate for the reactivity change caused by power feedback, moderator temperature and xenon oscillation, and the number of steps of movement of the first rod group is adjusted to compensate for the axial power deviation of the reactor caused by the reactivity change and the movement of the third rod group;

[0090] When the output power of the reactor is less than the preset power, the number of steps of movement of the second rod group and the third rod group is adjusted to compensate for the reactivity change caused by power feedback, moderator temperature and xenon oscillation, and the number of steps of movement of the first rod group is adjusted to compensate for the axial power deviation of the reactor caused by the reactivity change and the movement of the second rod group and the third rod group.

[0091] In this way, by optimizing the arrangement of the reactor rod group, the first rod group adjusts the axial power offset of the reactor, and when the output power of the reactor is less than the preset power, the second rod group is controlled to intervene, and the power is adjusted by the second rod group to compensate for the reactivity change caused by power feedback; when the output power of the reactor is greater than or equal to the preset power, the second rod group is controlled to stop intervening, and the reactivity change caused by power feedback, moderator temperature and xenon oscillation is compensated by the third rod group; at the same time, the axial power offset of the reactor is compensated by the first rod group, so that the reactor has the ability of non-boron load tracking, and the insertion depth of the first rod group is reduced, thereby reducing the disturbance of the reactor rod group to the core reactivity, improving the safety margin of the reactor, and improving the safety and operation flexibility of the nuclear power plant.

[0092] In one example, when the output power of the reactor is greater than or equal to a preset power, adjusting the number of steps of the third rod group movement to compensate for the reactivity change caused by power feedback, moderator temperature, and xenon oscillation, and adjusting the number of steps of the first rod group movement to compensate for the reactor axial power deviation caused by the reactivity change and the movement of the third rod group, comprises:

[0093] When the target power is greater than or equal to the preset power and the output power of the reactor is greater than the target power, the number of steps of the movement of the third rod group is controlled to increase so as to compensate for the reactivity change caused by power feedback, moderator temperature and xenon oscillation, and the number of steps of the movement of the first rod group is controlled to increase so as to compensate for the axial power deviation of the reactor caused by the reactivity change and the movement of the third rod group, so that the output power of the reactor is adjusted down to the target power;

[0094] When the output power of the reactor is greater than or equal to the preset power and the target power is greater than the output power of the reactor, the number of steps of the movement of the third rod group is controlled to decrease so as to compensate for the reactivity change caused by power feedback, moderator temperature and xenon oscillation, and the number of steps of the movement of the first rod group is controlled to decrease so as to compensate for the axial power deviation of the reactor caused by the reactivity change and the movement of the third rod group, so that the output power of the reactor is adjusted upward to the target power;

[0095] When the target power is less than the preset power and the output power of the reactor is greater than the preset power, the number of steps of the third rod group is controlled to increase so as to compensate for the reactivity change caused by power feedback, moderator temperature and xenon oscillation, and the number of steps of the first rod group is controlled to increase so as to compensate for the reactivity change and the axial power deviation of the reactor caused by the movement of the third rod group, so that the output power of the reactor is adjusted down to the preset power; then, the second rod group is controlled to intervene, and the number of steps of the second rod group and the third rod group is controlled to increase so as to compensate for the reactivity change caused by power feedback, moderator temperature and xenon oscillation, and the number of steps of the first rod group is controlled to decrease so as to compensate for the reactivity change and the axial power deviation of the reactor caused by the movement of the second rod group and the third rod group, so that the output power of the reactor is adjusted down from the preset power to the target power.

[0096] By optimizing the arrangement of the reactor rod group, the first rod group adjusts the axial power offset of the reactor, and controls the second rod group to stop intervening when the output power of the reactor is greater than or equal to the preset power, and the third rod group compensates for the reactivity changes caused by power feedback, moderator temperature and xenon oscillation; at the same time, by compensating the axial power offset of the reactor by the set first rod group, the reactor has the ability of non-adjustable boron load tracking, and reduces the insertion depth of the first rod group, thereby reducing the disturbance of the reactor rod group to the core reactivity, improving the safety margin of the reactor, and improving the safety and operation flexibility of the nuclear power plant.

[0097] In one example, when the output power of the reactor is less than the preset power, adjusting the number of steps of movement of the second rod group and the third rod group to compensate for the reactivity change caused by power feedback, moderator temperature and xenon oscillation, and adjusting the number of steps of movement of the first rod group to compensate for the reactor axial power deviation caused by the reactivity change and the movement of the second rod group and the third rod group, comprises:

[0098] When the target power is less than or equal to the preset power and the output power of the reactor is less than the target power, the number of steps of the movement of the second rod group and the third rod group is controlled to decrease so as to compensate for the reactivity change caused by power feedback, moderator temperature and xenon oscillation, and the number of steps of the movement of the first rod group is controlled to increase so as to compensate for the axial power deviation of the reactor caused by the reactivity change and the movement of the second rod group and the third rod group, so that the output power of the reactor is increased to the target power;

[0099] When the output power of the reactor is less than or equal to the preset power and the target power is less than the output power of the reactor, the number of steps of the movement of the second rod group and the third rod group is controlled to increase so as to compensate for the reactivity change caused by power feedback, moderator temperature and xenon oscillation, and the number of steps of the movement of the first rod group is controlled to decrease so as to compensate for the axial power deviation of the reactor caused by the reactivity change and the movement of the second rod group and the third rod group, so that the output power of the reactor is adjusted down to the target power;

[0100] In the case that the target power is greater than the preset power and the output power of the reactor is less than the preset power, the number of steps of the movement of the second rod group and the third rod group is controlled to decrease so as to compensate for the reactivity change caused by power feedback, moderator temperature and xenon oscillation, and the number of steps of the movement of the first rod group is controlled to increase so as to compensate for the reactivity change and the axial power deviation of the reactor caused by the movement of the second rod group and the third rod group, so that the output power of the reactor is increased to the preset power; then, the second rod group is controlled to stop intervening, and the number of steps of the movement of the third rod group is controlled to decrease so as to compensate for the reactivity change caused by power feedback, moderator temperature and xenon oscillation, and the number of steps of the movement of the first rod group is controlled to decrease so as to compensate for the axial power deviation of the reactor caused by the reactivity change and the movement of the third rod group, so that the output power of the reactor is increased from the preset power to the target power.

[0101] By optimizing the arrangement of the reactor rod group, the first rod group adjusts the axial power offset of the reactor, and controls the second rod group to intervene when the output power of the reactor is less than the preset power, and the power is adjusted by the second rod group to compensate for the reactivity change caused by power feedback; at the same time, by compensating the axial power offset of the reactor by the set first rod group, the reactor has the ability of non-boron load tracking, and the insertion depth of the first rod group is reduced, thereby reducing the disturbance of the reactor rod group to the core reactivity, improving the safety margin of the reactor, and improving the safety and operation flexibility of the nuclear power plant.

[0102] It should be noted that, in this article, the terms "include", "comprises" or any other variations thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or device. In the absence of further restrictions, an element defined by the sentence "comprises a ..." does not exclude the existence of other identical elements in the process, method, article or device including the element.

[0103] The embodiments of the present invention are described above in conjunction with the accompanying drawings, but the present invention is not limited to the above-mentioned specific implementation modes, which are merely illustrative rather than restrictive. Under the guidance of the present invention, ordinary technicians in this field can also make many forms without departing from the scope of protection of the present invention and the claims, all of which are within the protection of the present invention.

Claims

1. A core, characterized in that: include: a first rod group, the first rod group being used to adjust the reactor axial power offset; a second rod group, the second rod group being used to compensate for a reactivity change caused by power feedback; a third rod group, the third rod group being used to compensate for the change in the reactivity caused by the moderator temperature and the xenon oscillation; a control unit, the control unit being electrically connected to the first rod group, the second rod group and the third rod group respectively; Wherein, the control unit is used for: When the output power of the reactor is greater than or equal to a preset power, the number of steps of movement of the third rod group is adjusted to compensate for the reactivity change caused by power feedback, moderator temperature and xenon oscillation, and the number of steps of movement of the first rod group is adjusted to compensate for the axial power deviation of the reactor caused by the reactivity change and the movement of the third rod group; When the output power of the reactor is less than the preset power, the number of steps of movement of the second rod group and the third rod group is adjusted to compensate for the reactivity change caused by power feedback, moderator temperature and xenon oscillation, and the number of steps of movement of the first rod group is adjusted to compensate for the axial power deviation of the reactor caused by the reactivity change and the movement of the second rod group and the third rod group.

2. The core according to claim 1, characterized in that: The preset power ranges from 80% to 90% of the full power of the reactor.

3. The core according to claim 1, characterized in that: In the case of load following operation power reduction and when the output power of the reactor is greater than or equal to the preset power, the number of steps of movement of the third rod group is increased so that the third rod group moves in the direction of inserting into the core, and the number of steps of movement of the first rod group is adjusted so that the axial power deviation of the reactor is controlled within a first preset range; In the case of load following operation power reduction, when the output power of the reactor is less than the preset power, the number of steps of movement of the second rod group and the third rod group is increased so that the second rod group and the third rod group move in the direction of inserting into the core, and the number of steps of movement of the first rod group is adjusted so that the axial power deviation of the reactor is controlled within a second preset range; wherein, in the entire load following operation power reduction process, the number of steps of movement of the first rod group ranges from 0 to 41 steps; When the load following operation is performed and the output power of the reactor is less than the preset power, the number of steps of movement of the second rod group and the third rod group is reduced so that the second rod group and the third rod group move in a direction of withdrawing from the core, and the number of steps of movement of the first rod group is adjusted so that the axial power deviation of the reactor is controlled within a third preset range; When the load following operation is performed to increase the power and the output power of the reactor is greater than or equal to the preset power, the number of steps of movement of the third rod group is reduced so that the third rod group moves in the direction of withdrawing the core, and the number of steps of movement of the first rod group is adjusted so that the axial power offset of the reactor is controlled within a fourth preset range; wherein, during the entire load following operation to increase the power, the number of steps of movement of the first rod group ranges from 41 steps to 0 steps.

4. The core according to claim 1, characterized in that: The first rod group is a black rod group, the second rod group is the black rod group, and the third rod group is a gray rod group. The loading amount of absorber material in the black rod group is higher than the loading amount of absorber material in the gray rod group.

5. The core according to claim 1, characterized in that: The second rod group includes a first power regulating rod group, a second power regulating rod group and a third power regulating rod group. The first power regulating rod group, the second power regulating rod group and the third power regulating rod group operate in tandem in sequence to adjust the output power of the reactor to different amplitudes during the load tracking process.

6. The core according to claim 1, characterized in that: The third rod group includes a first temperature regulating rod group, a second temperature regulating rod group, a third temperature regulating rod group and a fourth temperature regulating rod group. The first temperature regulating rod group, the second temperature regulating rod group, the third temperature regulating rod group and the fourth temperature regulating rod group operate in sync and are used to adjust the output power and temperature of the reactor to different extents during the load tracking process.

7. The core according to claim 1, characterized in that: Also included is a fourth rod group electrically connected to the control unit, wherein the fourth rod group is used to provide a safety shutdown control capability.

8. A control method for a reactor rod group, applied to a core according to any one of claims 1 to 7, characterized in that: The method comprises: acquiring the output power of the reactor upon receiving the target instruction, wherein the target instruction includes controlling the output power of the reactor to reach the target power; When the output power of the reactor is greater than or equal to a preset power, the number of steps of movement of the third rod group is adjusted to compensate for the reactivity change caused by power feedback, moderator temperature and xenon oscillation, and the number of steps of movement of the first rod group is adjusted to compensate for the axial power deviation of the reactor caused by the reactivity change and the movement of the third rod group; When the output power of the reactor is less than the preset power, the number of steps of movement of the second rod group and the third rod group is adjusted to compensate for the reactivity change caused by power feedback, moderator temperature and xenon oscillation, and the number of steps of movement of the first rod group is adjusted to compensate for the axial power deviation of the reactor caused by the reactivity change and the movement of the second rod group and the third rod group.

9. The method according to claim 8, characterized in that When the output power of the reactor is greater than or equal to a preset power, adjusting the number of steps of movement of the third rod group to compensate for the reactivity change caused by power feedback, moderator temperature and xenon oscillation, and adjusting the number of steps of movement of the first rod group to compensate for the reactor axial power deviation caused by the reactivity change and the movement of the third rod group, comprising: When the target power is greater than or equal to the preset power and the output power of the reactor is greater than the target power, the number of steps of the movement of the third rod group is controlled to increase so as to compensate for the reactivity change caused by power feedback, moderator temperature and xenon oscillation, and the number of steps of the movement of the first rod group is controlled to increase so as to compensate for the axial power deviation of the reactor caused by the reactivity change and the movement of the third rod group, so that the output power of the reactor is adjusted down to the target power; When the output power of the reactor is greater than or equal to the preset power and the target power is greater than the output power of the reactor, the number of steps of the movement of the third rod group is controlled to decrease so as to compensate for the reactivity change caused by power feedback, moderator temperature and xenon oscillation, and the number of steps of the movement of the first rod group is controlled to decrease so as to compensate for the axial power deviation of the reactor caused by the reactivity change and the movement of the third rod group, so that the output power of the reactor is adjusted upward to the target power; When the target power is less than the preset power and the output power of the reactor is greater than the preset power, the number of steps of the third rod group is controlled to increase so as to compensate for the reactivity change caused by power feedback, moderator temperature and xenon oscillation, and the number of steps of the first rod group is controlled to increase so as to compensate for the reactivity change and the axial power deviation of the reactor caused by the movement of the third rod group, so that the output power of the reactor is adjusted down to the preset power; then, the second rod group is controlled to intervene, and the number of steps of the second rod group and the third rod group is controlled to increase so as to compensate for the reactivity change caused by power feedback, moderator temperature and xenon oscillation, and the number of steps of the first rod group is controlled to decrease so as to compensate for the reactivity change and the axial power deviation of the reactor caused by the movement of the second rod group and the third rod group, so that the output power of the reactor is adjusted down from the preset power to the target power.

10. The method according to claim 8, characterized in that When the output power of the reactor is less than the preset power, the number of steps of movement of the second rod group and the third rod group is adjusted to compensate for the reactivity change caused by power feedback, moderator temperature and xenon oscillation, and the number of steps of movement of the first rod group is adjusted to compensate for the reactor axial power deviation caused by the reactivity change and the movement of the second rod group and the third rod group, comprising: When the target power is less than or equal to the preset power and the output power of the reactor is less than the target power, the number of steps of the movement of the second rod group and the third rod group is controlled to decrease so as to compensate for the reactivity change caused by power feedback, moderator temperature and xenon oscillation, and the number of steps of the movement of the first rod group is controlled to increase so as to compensate for the axial power deviation of the reactor caused by the reactivity change and the movement of the second rod group and the third rod group, so that the output power of the reactor is increased to the target power; When the output power of the reactor is less than or equal to the preset power and the target power is less than the output power of the reactor, the number of steps of the movement of the second rod group and the third rod group is controlled to increase so as to compensate for the reactivity change caused by power feedback, moderator temperature and xenon oscillation, and the number of steps of the movement of the first rod group is controlled to decrease so as to compensate for the axial power deviation of the reactor caused by the reactivity change and the movement of the second rod group and the third rod group, so that the output power of the reactor is adjusted down to the target power; In the case that the target power is greater than the preset power and the output power of the reactor is less than the preset power, the number of steps of the movement of the second rod group and the third rod group is controlled to decrease so as to compensate for the reactivity change caused by power feedback, moderator temperature and xenon oscillation, and the number of steps of the movement of the first rod group is controlled to increase so as to compensate for the reactivity change and the axial power deviation of the reactor caused by the movement of the second rod group and the third rod group, so that the output power of the reactor is increased to the preset power; then, the second rod group is controlled to stop intervening, and the number of steps of the movement of the third rod group is controlled to decrease so as to compensate for the reactivity change caused by power feedback, moderator temperature and xenon oscillation, and the number of steps of the movement of the first rod group is controlled to decrease so as to compensate for the axial power deviation of the reactor caused by the reactivity change and the movement of the third rod group, so that the output power of the reactor is increased from the preset power to the target power.

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