JP2019148518A - Nuclear reactor shutdown device, nuclear reactor shutdown method and reactor core design method - Google Patents

Abstract

To provide a nuclear reactor shutdown device or the like that can achieve improvement in a nuclear reactor shutdown performance with a control rod effectively used, even when a number of installations of control rods grows.SOLUTION: A nuclear reactor shutdown device comprises: a plurality of control rods to be inserted into a reactor core of a nuclear reactor; a control rod drive device; and a safety protection system facility. The plurality of control rods have: a control bank 103 that is composed of one part of the plurality of control rods for control of an output of the nuclear reactor; and a shutdown bank that is composed of other part of the plurality of control rods for a shutdown of the output of the nuclear reactor. The shutdown bank at least includes: a first shutdown bank 101 that is composed of one part of the control rod of the plurality of control rods in the shutdown bank; and a second shutdown bank 102 that is composed of other part of the control rod. The safety protection system facility is configured to, at a time of abnormality of the nuclear reactor, insert the control rod of the first shutdown bank 101 and the control rod of the second shutdown bank 102 into the reactor core with an insertion timing made different therebetween.SELECTED DRAWING: Figure 4

Description

  The present invention relates to a nuclear reactor shutdown apparatus, a nuclear reactor shutdown method, and a reactor core design method for shutting down a nuclear reactor.

  Conventionally, when an abnormal event occurs from when an abnormality occurs in the reactor until the reactor trips, the abnormality is judged, and after the abnormality is judged, mitigation measures such as runback and control rod insertion are performed. A system is known (see, for example, Patent Document 1).

Japanese Patent Laid-Open No. 11-030893

  By the way, in order to improve the safety of the nuclear power plant, it has been studied to enhance the reactor shutdown performance by the control rod. Specifically, in order to enhance the reactor shutdown performance with control rods, it has been studied to increase the number of control rods installed in the reactor. If the number of control rods is increased, the number of control rods may be larger than the number of control rods required to shut down the reactor. In this case, the control rods cannot be used effectively. there is a possibility.

  Therefore, the present invention provides a reactor shutdown device, a reactor shutdown method, and a reactor shutdown method capable of effectively utilizing the control rods to improve reactor shutdown performance even when the number of installed control rods increases. It is an object of the present invention to provide a core design method.

  The reactor shutdown device of the present invention controls a plurality of control rods inserted into a reactor core, a control rod driving device for driving the plurality of control rods, and driving of the control rods by the control rod driving device. A plurality of the control rods, a control bank including a plurality of the control rods for controlling the output of the nuclear reactor, and another for stopping the output of the nuclear reactor. A stop bank consisting of a plurality of the control rods, and the stop bank is a first stop bank consisting of some of the control rods among the plurality of control rods in the stop bank; A second stop bank comprising at least some of the other control rods, and the control unit is configured to control the control rods of the first stop bank and the second stop bank when the nuclear reactor is abnormal. Insert the control rod into the insertion timing. Not allowed, characterized in that inserted into the reactor core.

  The reactor shutdown method of the present invention is a reactor shutdown method in which the reactor is stopped by a control unit that controls driving of a plurality of control rods inserted into the core of the reactor, and the plurality of the controls A rod is a control bank consisting of a part of the control rods for controlling the output of the reactor and a stop consisting of a plurality of other control rods for stopping the output of the reactor. The stop bank is a first stop bank made up of a part of the control rods and a second part made up of the other control rods. The control rod of the first stop bank and the control rod of the second stop bank are inserted into the core at different insertion timings when the reactor is abnormal. It is characterized by that.

  According to these configurations, when the nuclear reactor is abnormal, the control rods of the first stop bank and the control rods of the second stop bank are inserted into the core with different insertion timings. It is possible to exhibit the reactor shutdown function using the control rods and the reactor shutdown function using the control rods of the second shutdown bank. For this reason, since a plurality of reactor shutdown functions can be exhibited, it is possible to effectively utilize the control rods and improve the reactor shutdown performance.

  Further, when the control unit acquires a reactor trip signal for stopping the reactor, the control unit executes insertion of the control rod of the control bank and the first stop bank into the core while the core When the insertion of the control rod of the second stop bank into the reactor is not executed, and a recriticality detection signal output when the reactor detects a recriticality event is acquired, the second to the core is obtained. It is preferable to perform the insertion of the control rod in the stop bank.

  According to this configuration, the reactor trip can be performed by inserting the control rod of the control bank and the control rod of the first stop bank into the core. In addition, even when the control rod of the control bank and the control rod of the first stop bank are inserted into the core, the reactor is shut down by the control rod of the second stop bank even when the nuclear reactor transitions to the recritical state. Measures can be taken. For this reason, the safety of the nuclear reactor can be improved. Here, when the nuclear reactor shifts to recriticality, there is a boric acid water injection facility for injecting boric acid water as an apparatus for stopping the nuclear reactor. The control rod of the second stop bank may be provided together with the boric acid water injection facility, or the boric acid water injection facility can be saved by providing the control rod of the second stop bank as an alternative function of the boric acid water injection facility. May be.

  The control rod includes a first control rod and a second control rod having higher neutron absorption performance than the first control rod, and the control rod of the second stop bank is the first stop bank. It is preferable that the ratio of the second control rod is larger than that of the control rod.

  According to this configuration, since the configuration of the control rod of the first stop bank and the configuration of the control rod of the second stop bank can be made different, the reactor stop function of the first stop bank and the second stop bank The reactor shutdown function can be made different, and can be made highly versatile. For example, by inserting the control rods of the second stop bank having a large proportion of the second control rods into the core of the reactor that is going to recriticality, the reactor can be quickly moved to the subcritical state.

  Further, the fuel contained in the core has a different burnup, and the control rod of the second stop bank has a lower burnup than the control rod of the first stop bank. It is preferable to arrange on the near side.

  According to this configuration, since the fuel with the smallest burnup such as new fuel emits a lot of neutrons by the reaction, the control rods of the second stop bank having a large proportion of the second control rods are arranged nearby. Since the reaction can be suppressed by suitably absorbing neutrons, the reactor can be suitably stopped.

  The fuel having the latest burnup is a new fuel that is newly loaded into the nuclear reactor at the time of refueling, and the control rod of the second stop bank is disposed adjacent to the new fuel. It is preferable.

  According to this configuration, the position of the control rod of the second stop bank with respect to the new fuel can be set to an appropriate position. The control rods of the second stop bank may be disposed adjacent to the new fuel in the horizontal direction or may be disposed adjacent to the vertical direction, and are not particularly limited.

  Moreover, it is preferable that the control rods of the control bank are disposed on fuels other than the new fuel.

  According to this configuration, the fuel other than the new fuel is a fuel that has been combusted. Then, when controlling the output of the nuclear reactor, it is possible to appropriately control the output of the nuclear reactor by inserting / removing the control rod of the control bank into / from fuel other than new fuel.

  The total number of the control rods in the control bank and the number of control rods in the first stop bank is preferably larger than the number of control rods in the second stop bank. .

  According to this configuration, the reactor trip can be appropriately performed by the control bank and the first stop bank having a large number of control rods. The total number of control rods in the control bank and the first stop bank is the number that can be shifted from the high temperature full power state to the high temperature stop state during the reactor trip, and the rest is the control of the second stop bank. The number of bars is recommended.

  The core design method of the present invention is a core design method for designing a loading pattern of fuel loaded in a nuclear reactor, wherein a plurality of control rods inserted in the core of the nuclear reactor control the output of the nuclear reactor. A control bank composed of a part of the plurality of control rods and a stop bank composed of another part of the plurality of control rods for stopping the output of the nuclear reactor, At least a first stop bank made up of some of the control rods and a second stop bank made up of some other control rods of the plurality of control rods in the stop bank. The new fuel to be newly loaded in the reactor is arranged so that the control rod of the second stop bank is closer to the control rod than the control rod of the first stop bank. And

  According to this configuration, it is possible to appropriately arrange the fuel with respect to the plurality of control rods in the control bank, the first stop bank, and the second stop bank in consideration of the reactor shutdown.

FIG. 1 is a schematic configuration diagram of a nuclear facility according to the present embodiment. FIG. 2 is a longitudinal sectional view showing a pressurized water reactor included in the nuclear facility of FIG. FIG. 3 is a configuration diagram around the reactor shutdown device according to the present embodiment. FIG. 4 is a schematic diagram illustrating an example of a control rod unit according to the present embodiment.

  Embodiments according to the present invention will be described below in detail with reference to the drawings. In addition, this invention is not limited by this embodiment. In addition, constituent elements in the following embodiments include those that can be easily replaced by those skilled in the art or those that are substantially the same. Furthermore, the constituent elements described below can be appropriately combined, and when there are a plurality of embodiments, the embodiments can be combined.

[This embodiment]
FIG. 1 is a schematic configuration diagram of a nuclear facility according to the first embodiment. A nuclear facility (nuclear facility) 1 has a nuclear reactor 2. As the nuclear reactor 2, for example, a pressurized water reactor (PWR) is used. A nuclear facility 1 using this pressurized water reactor 2 includes a reactor cooling system (primary cooling system) 100 including the reactor 2 and a turbine system (secondary cooling system) 200 that exchanges heat with the reactor cooling system 100. It consists of. In the reactor cooling system 100, a primary coolant flows, and in the turbine system 200, a secondary coolant flows.

  The reactor cooling system 100 has a steam generator 4 connected to the reactor 2 via a cold leg 3a and a hot leg 3b. The hot leg 3b is provided with a pressurizer 5, and the cold leg 3a is provided with a primary coolant pump 6. The reactor 2, the cold leg 3 a, the hot leg 3 b, the steam generator 4, the pressurizer 5, and the primary coolant pump 6 are accommodated in the reactor containment vessel 7.

  The nuclear reactor 2 is a pressurized water nuclear reactor as described above, and the inside is filled with the primary coolant. The primary coolant is light water in which boron used as a neutron moderator is dissolved. In the nuclear reactor 2, a large number of fuel assemblies 8 are accommodated in the reactor vessel 10, and a large number of control rods 9 for controlling the nuclear fission of the fuel assemblies 8 are inserted into and removed from the fuel assemblies 8. It is provided as possible. The control rod 9 is driven in the insertion / removal direction with respect to the fuel assembly 8 by the control rod driving device 20. When the control rod 9 is inserted into the fuel assembly 8 by the control rod driving device 20, the nuclear reaction in the fuel assembly 8 decreases and stops. On the other hand, when the control rod 9 is pulled out by the control rod driving device 20, the nuclear reaction in the fuel assembly 8 increases and becomes a critical state. The control rod drive device 20 is configured to insert the control rod 9 into the fuel assembly 8 when the supply of electric power is cut off and the electric power is lost.

  A series of operations in the reactor cooling system 100 of the nuclear facility 1 will be described. When the fuel assembly 8 is fissioned in the nuclear reactor 2 while controlling the fission reaction by the control rod 9, thermal energy is generated by the fission. When the primary coolant in the nuclear reactor 2 is heated by this thermal energy, the heated primary coolant is sent to the steam generator 4 through the hot leg 3b by the primary coolant pump 6. The high temperature primary coolant passing through the hot leg 3b is pressurized by the pressurizer 5 to suppress boiling, and flows into the steam generator 4 in a state of high temperature and pressure. The high-temperature and high-pressure primary coolant flowing into the steam generator 4 is cooled by exchanging heat with the secondary coolant, and the cooled primary coolant is passed through the cold leg 3a by the primary coolant pump 6 to the nuclear reactor. Sent to 2. Then, the cooled primary coolant flows into the reactor 2, so that the reactor 2 is cooled. Thus, the primary coolant circulates between the nuclear reactor 2 and the steam generator 4.

  The turbine system 200 includes a turbine 12 connected to the steam generator 4 via the steam pipe 11, a condenser 13 connected to the turbine 12, and a water supply pipe 14 connecting the condenser 13 and the steam generator 4. A water supply pump 15 interposed between the two. The turbine 12 is connected to a generator 16.

  A series of operations in the turbine system 200 of the nuclear facility 1 will be described. When steam flows from the steam generator 4 into the turbine 12 via the steam pipe 11, the turbine 12 rotates. When the turbine 12 rotates, the generator 16 connected to the turbine 12 generates power. Thereafter, the steam flowing out of the turbine 12 flows into the condenser 13. The condenser 13 has a cooling pipe 17 disposed therein, and one of the cooling pipes 17 is connected to a water intake pipe 18 for supplying cooling water (for example, seawater). A drain pipe 19 for draining the cooling water is connected to. The condenser 13 cools the steam flowing in from the turbine 12 by the cooling pipe 17, thereby returning the steam to a liquid. The secondary coolant that has become liquid is sent to the steam generator 4 via the water supply pipe 14 by the water supply pump 15. The secondary coolant sent to the steam generator 4 becomes steam again by exchanging heat with the primary coolant in the steam generator 4.

  FIG. 2 is a longitudinal sectional view showing a pressurized water reactor included in the nuclear power plant of FIG. As shown in FIG. 2, in the pressurized water reactor 2, the reactor vessel 10 includes a reactor vessel main body 52 and a reactor vessel lid (which is attached to the upper portion thereof) so that the in-reactor structure can be inserted therein. The reactor vessel body 53 is fixed to the reactor vessel body 52 by a plurality of stud bolts 54 and nuts 55 so as to be opened and closed.

  The reactor vessel main body 52 has a cylindrical shape whose upper portion can be opened by removing the reactor vessel lid 53 and whose lower portion is closed by a lower mirror 56 having a hemispherical shape. In the reactor vessel main body 52, an inlet nozzle 57 for supplying light water (primary coolant) as primary cooling water and an outlet nozzle 58 for discharging light water are formed in the upper part. The inlet nozzle 57 is connected to the cold leg 3a. The outlet nozzle 58 is connected to the hot leg 3b.

  The reactor vessel main body 52 has a reactor core 61 disposed therein, and the upper portion is supported by the inner wall surface of the reactor vessel main body 52. The reactor vessel main body 52 has an upper core support plate 62 disposed therein, and the upper core support plate 62 is supported at the upper part of the core tank 61. In the upper core support plate 62, the upper core plate 64 is suspended and supported by a plurality of core support rods 63.

  A lower core support plate 65 is supported below the reactor core 61, and the outer periphery of the lower core support plate 65 is positioned and supported on the inner wall surface of the reactor vessel body 52 by a positioning member 66. The core tank 61 has a lower core plate 67 supported at the lower part thereof. The core 68 is configured by arranging a large number of fuel assemblies 8 in an area defined by an upper core plate 64 and a lower core plate 67 in the core tank 61. A large number of control rods 9 are arranged inside the core 68, and a plurality of these control rods 9 are combined to form a control rod cluster 71, which can be inserted into the fuel assembly 8. The upper core support plate 62 is fixed with a large number of control rod cluster guide tubes 72 extending vertically through the upper core support plate 62. Each control rod cluster guide tube 72 is connected to the upper core plate 64 at the lower end, and the control rod cluster 71 can be inserted therein.

  The upper part of the reactor vessel lid 53 has a hemispherical shape, and the control rod driving device 20 of a magnetic jack is disposed on the upper part. The plurality of control rod cluster guide tubes 72 have upper end portions extending upward through the nozzles of the reactor vessel lid 53, and a control rod cluster drive shaft 74 extending downward from the control rod drive device 20 is controlled by the control rod cluster guide tube 72. The rod cluster guide tube 72 is inserted. The control rod cluster drive shaft 74 is movable in the vertical direction by the control rod drive device 20, extends through the control rod cluster guide tube 72 to the core 68, and is connected to the control rod cluster 71. The control rod drive unit 20 controls the reactor power by inserting / removing each control rod 9 of the control rod cluster 71 with respect to the core 68.

  The reactor vessel main body 52 is provided with a number of instrumentation nozzles 75 penetrating the lower mirror 56, and each instrumentation nozzle 75 has an in-reactor instrumentation guide tube 76 connected to the upper end portion inside the reactor. On the other hand, a conduit tube 77 is connected to the lower end portion outside the furnace, and a plurality of connecting plates 78 are attached to each in-core instrumentation guide pipe 76. The thimble tube 79 passes from the conduit tube 77 through the instrumentation nozzle 75 and the in-core instrumentation guide tube 76, passes through the lower core support plate 65 and the lower core plate 67, and reaches the core 68 (fuel assembly 8). It is inserted.

  In the nuclear reactor vessel 10, an upper plenum 80 is provided above the core 68, a lower plenum 81 is provided below, and a downcomer portion 82 is formed therebetween.

  In addition, the nuclear facility 1 includes a control system 300 that controls the reactor cooling system 100 and the turbine system 200. The control system 300 includes a safety control system facility 30 in addition to a central control facility (not shown). As shown in FIG. 3, the safety protection system 30 controls each device provided in the nuclear facility 1 so that the nuclear facility 1 is safely stopped when an abnormality occurs in the nuclear facility 1.

  FIG. 3 is a configuration diagram around the reactor shutdown device according to the present embodiment. The control system 300 of the nuclear facility 1 has a nuclear reactor stop device 35 that makes an emergency stop of the nuclear reaction of the nuclear reactor 2 assuming that an abnormality occurs in the nuclear reactor 2. The reactor shutdown device 35 includes the safety protection system facility (control unit) 30, the reactor trip circuit breaker 37, the control rod driving device 20, and the control rod 9.

  The safety protection system 30 is a so-called digital facility equipped with an arithmetic device such as a CPU and a storage device such as an HDD, and by executing various programs stored in the storage device by the arithmetic device, the safety of the nuclear facility 1 It is a facility that can control the protection system. The safety protection system is a functional system having functions of stopping the nuclear reaction of the nuclear reactor 2, cooling the nuclear facility 1, and preventing leakage of radioactive materials from the nuclear facility 1. The safety protection system 30 has a high operation guarantee so that the safety protection system 30 can operate reliably and can operate even in a severe environment.

  Various detection sensors arranged in the nuclear facility 1 are connected to the safety protection system 30, and whether or not an abnormality has occurred in the nuclear facility 1 based on the detection signals output from the various detection sensors. Judging. When it is determined that an abnormality has occurred in the nuclear facility 1, the safety protection system facility 30 transmits a reactor trip signal for stopping the reactor 2 to the reactor trip breaker 37.

  The nuclear reactor trip breaker 37 cuts off the electric power supplied to the control rod driving device 20 based on the nuclear reactor trip signal transmitted from the safety protection system facility 30.

  The reactor shutdown device 35 outputs a reactor trip signal from the safety protection system facility 30 to the reactor trip breaker 37. Then, the reactor trip breaker 37 enters an open state in which the power supply is cut off based on the input reactor trip signal, and cuts off the electric power supplied to the control rod drive device 20. When the electric power supplied to the control rod driving device 20 is cut off, the support state of the control rod 9 is released, so that the control rod 9 falls to the fuel assembly 8 by its own weight. Then, by inserting the control rod 9 into the fuel assembly 8, the nuclear reaction of the fuel is reduced and the nuclear reactor 2 is stopped.

  FIG. 4 is a schematic diagram illustrating an example of a control rod unit according to the present embodiment. 4 shows an example of the arrangement of the fuel assemblies 8 and the control rod clusters 71 in the core 68 of FIG. The control rod unit 90 includes each control rod cluster 71. The fuel assembly 8 includes a plurality of new fuels 91 and a plurality of spent fuels 92. Each control rod cluster 71 includes a control rod cluster formed by standard control rod 94 (hereinafter simply referred to as standard control rod 94) or a control rod cluster formed by first high performance control rod 95 (hereinafter simply referred to as first high performance control rod). 95) and a control rod cluster by the second high performance control rod 97 (hereinafter simply referred to as the second high performance control rod 97). That is, the control rod unit 90 includes at least one of the standard control rod 94 and the first high performance control rod 95 and the second high performance control rod 97. In the present embodiment, the above-described control rod is used, but a configuration further including a gray rod may be used, and is not particularly limited.

  As shown in FIG. 4, the region inside the core 68 is divided into horizontal coordinates A to R from right to left in FIG. 4, and vertical coordinates 1 to 15 from top to bottom in FIG. It is divided into a grid and managed. In each grid-like section of the region inside the core 68, either the new fuel 91 or the spent fuel 92, which is a fuel having a different burnup, is disposed as the fuel assembly 8. In addition, a part of each grid-like section inside the core 68 includes, as each control rod cluster 71, a standard control rod 94 or a first high-performance control rod 95, a second high-performance control rod 97, One of them is arranged. In FIG. 4, the positions of the standard control rod 94 or the first high performance control rod 95 and the second high performance control rod 97 are simply shown.

  The new fuel 91 is a fuel assembly 8 that has never been used for nuclear fission as a fuel before being placed in a nuclear reactor. On the other hand, the spent fuel 92 is used for nuclear fission at least once in the fuel assembly 8 as fuel. Therefore, the new fuel 91 releases a larger amount of neutrons than the spent fuel 92 and causes a fission reaction. The spent fuel 92 emits a small amount of neutrons compared to the new fuel 91. In the pressurized water reactor 2, a plurality of new fuels 91 and a plurality of spent fuels 92 are mixed and inserted into the core 68.

  The standard control rod 94 uses, for example, an alloy containing silver, indium and cadmium (AIC: Ag-In-Cd) as a neutron absorbing material. AIC has standard neutron absorption performance as a neutron absorbing material. The standard control rod 94 is the most standard control rod among the standard control rod 94, the first high performance control rod 95, and the second high performance control rod 97. The standard control rod 94 has standard neutron absorption performance. That is, the standard control rod 94 has a neutron absorption performance slightly lower than that of the first high performance control rod 95 and lower than that of the second high performance control rod 97, and is the lowest as a whole. It is like.

  Since the standard control rod 94 has the above-described configuration, it is possible to stably adjust the reactivity of fission in the reactor core 68. Therefore, the output of the pressurized water reactor 2 is suitable during normal operation of the pressurized water reactor 2. Can be controlled. Further, since the standard control rod 94 has a higher mass than the second high performance control rod 97, the standard control rod 94 has better drop characteristics in the core 68 than the second high performance control rod 97. When the reactor 2 is shut down, that is, when the reactor is tripped, the pressurized water reactor 2 can be suitably protected so as not to exceed the nuclear boiling limit (DNB). Here, the function of controlling the output during normal operation of the pressurized water reactor 2 and the function of protecting so as not to exceed the DNB during an atomic trip are collectively referred to as control protection performance. The standard control rod 94 has high control protection performance.

For the first high-performance control rod 95, for example, a neutron absorbing material having a configuration in which the range of 30% or more and less than 60% of the upper part of the AIC is replaced with B ₄ C (boron carbide) is used. . B ₄ C is a material having higher neutron absorption performance than AIC and lighter than AIC. Therefore, the first high performance control rod 95 has a higher neutron absorption function than the standard control rod 94. That is, the first high-performance control rod 95 has a slightly higher neutron absorption performance than the standard control rod 94 and a little lower than the second high-performance control rod 97, and is generally medium. The first high-performance control rod 95 is lighter than the standard control rod 94 because B ₄ C substitution is in the range of 30% or more and less than 60%, but the drop characteristics in the core 68 are greatly reduced. Absent. Therefore, the first high-performance control rod 95 has high control protection performance like the standard control rod 94.

For the second high performance control rod 97, as the neutron absorbing material, for example, a material in which the range of 60% or more of the upper part of the AIC is replaced with B ₄ C (boron carbide) is used. Therefore, the second high-performance control rod 97 has a higher neutron absorption performance than the first high-performance control rod 95. That is, the second high performance control rod 97 has higher neutron absorption performance than either the standard control rod 94 or the first high performance control rod 95. Therefore, the second high performance control rod 97 has a high stopping function because it can be adjusted to rapidly reduce the reactivity. Since the second high-performance control rod 97 has high neutron absorption performance, the pressurized water reactor 2 is suitably placed in a subcritical state at the time of steam line break (SLB) by rapidly reducing the reactivity. Required to maintain the pressurized water reactor 2 in a subcritical state when all AC power is lost (SBO: Station Black Out) and to move the pressurized water reactor 2 to a cold shutdown state. The temperature in the core 68 can be lowered to the desired temperature.

  The second high-performance control rod 97 has high neutron absorption performance and can maintain the pressurized water reactor 2 in a subcritical state during SLB or SBO. The second high performance control rod 97 can shift the pressurized water reactor 2 to a cold shutdown state with only the control rod while reducing the amount of boric acid used or without using boric acid at all. Here, the function of maintaining the pressurized water reactor 2 in the subcritical state at the time of SLB or SBO, and reducing the amount of boric acid used, or using the control water without using boric acid at all, only with the pressurized water atom The function of shifting the furnace 2 to the low temperature stop state is collectively referred to as stop performance. The second high performance control rod 97 has stop performance.

  The control rod 9 as described above includes a control bank 103 including a plurality of control rods 9 for controlling the output of the nuclear reactor 2 and a plurality of other partial plurals for stopping the output of the nuclear reactor 2. The control bank 9 is divided into stop banks. The control rods of the control bank 103 are control rods 9 used for controlling the output of the reactor 2 during normal operation. The control rod 9 of the stop bank is a control rod 9 used for stopping the nuclear reactor 2 in the event of an abnormality.

  As the control rod 9 of the control bank 103, the standard control rod 94 or the first high performance control rod 95 having high control protection performance is applied. In the present embodiment, the first high performance control rod 95 is applied as the control rod of the control bank 103. The control rod 9 of the control bank 103 is controlled to be inserted and removed by the control rod driving device 20 being controlled from the central control facility of the control system 300.

  The stop bank control rods 9 are divided into a first stop bank 101 composed of some control rods 9 and a second stop bank 102 composed of some other control rods 9 among the plurality of control rods 9. ing. In the present embodiment, the first stop bank 101 and the second stop bank 102 are divided into two, but there may be two or more, and there is no particular limitation. As the control rod 9 of the first stop bank 101, the first high performance control rod 95 having high control protection performance is applied. As a control rod of the second stop bank 102, a second high performance control rod 97 having stop performance is applied.

  Therefore, the control rods 9 of the control bank 103 and the first stop bank 101 become the first high performance control rod (first control rod) 95, and the control rod 9 of the second stop bank 102 becomes the second high performance control rod. It becomes a control rod (second control rod) 97. Therefore, the control rod 9 of the second stop bank 102 has higher neutron absorption performance than the control rod 9 of the first stop bank 101. The combination of the control rods 9 applied to the control bank 103, the first stop bank 101, and the second stop bank 102 described above is an example, and is not limited to this configuration. For example, the control rod 9 of the control bank 103 is a standard control rod (first control rod) 94, the control rod 9 of the first stop bank 101 is a first high performance control rod (first control rod) 95, and the second The control rod 9 of the stop bank 102 may be a second high performance control rod (second control rod) 97.

  Here, the safety protection system facility 30 makes the insertion timing of the control rod 9 of the first stop bank 101 different from that of the control rod 9 of the second stop bank 102 when the reactor trips in the SLB or SBO. Specifically, when the safety protection system facility 30 acquires a reactor trip signal for stopping the reactor 2, the safety protection system facility 30 inserts the control bank 103 and the control rod 9 of the first stop bank 101 into the core 68. Thus, the insertion of the control rod 9 of the second stop bank 102 into the core 68 is not executed. For this reason, as shown in FIG. 4, all of the first high performance control rods 95 are positioned to be inserted into the fuel assembly 8 (total insertion position), while the second high performance control rod 97 is All the positions are not inserted into the fuel assembly 8 (full extraction position).

  The safety protection system 30 detects an event in which the reactor 2 becomes recritical in a state in which the control rods 103 of the control bank 103 and the first stop bank 101 are in the full insertion position, and this detection signal is generated. When the recriticality detection signal is acquired, the control rod 9 of the second stop bank 102 is inserted into the core 68. In other words, the safety protection system 30 inserts the control rod 9 of the second stop bank 102 into the fuel assembly 8 when the nuclear reactor 2 attempts to shift from the subcritical state to the recritical state, Control to be in a critical state. For this reason, the control rod 9 of the 2nd stop bank 102 has a function equivalent to the boric-acid-water injection | pouring equipment which performs the shutdown procedure of a nuclear reactor when a nuclear reactor transfers to a recriticality.

  Here, the total number of control rods 9 (first high-performance control rods 95) combined with the number of control rods 9 in the control bank 103 and the number of control rods 9 in the first stop bank 101 is the second stop bank 102. The number of control rods 9 (second high-performance control rod 97) is larger. Specifically, the number of the first high performance control rods 95 (the control rod clusters 71) is 44, and the number of the second high performance control rods 97 (the control rod clusters 71) is 24. is there.

  Next, the positional relationship between the control rods 103 of the control bank 103, the first stop bank 101 and the second stop bank 102 and the fuel including the new fuel 91 and the used fuel 92 will be described. As described above, the core 68 includes the new fuel 91 and the spent fuel 92. The control rod 9 of the second stop bank 102 is disposed closer to the new fuel 91 having the smallest burnup than the control rod 9 of the first stop bank 101. Specifically, the control rod 9 of the second stop bank 102 is disposed adjacent to the new fuel 91. That is, the control rod 9 of the second stop bank 102 may be disposed immediately adjacent to the fuel assembly 8 of the new fuel 91 so that it can be inserted into and removed from the fuel assembly 8 made of the new fuel 91. The fuel 91 may be detachably disposed in the fuel assembly 8 adjacent to the fuel assembly 8. On the other hand, the control rod 9 of the control bank 103 is arranged so as to be able to be inserted into and removed from the fuel assembly 8 made of spent fuel 92 which is a fuel other than the new fuel 91.

  In the nuclear reactor 2 provided with the control rod unit 90 in which the control rods 9 are arranged as described above, in the core design method for designing the loading pattern of the fuel loaded in the nuclear reactor 2, Designed to satisfy the positional relationship with the fuel. That is, in the core design method, the control rod 9 of the second stop bank 102 is closer to the new fuel 91 loaded in the reactor 2 at the time of fuel replacement than the control rod 9 of the first stop bank 101. Arrange to be on the side. Specifically, at least one fuel assembly 8 into which the control rod 9 of the second stop bank 102 is inserted and removed is used as the fuel assembly 8 of the new fuel 91, and the control rod 9 of the control bank 103 is used. The core design is performed so that at least one fuel assembly 8 into and out of which is inserted and removed becomes the fuel assembly 8 of the spent fuel 92. Further, the core design is performed so that the control rod 9 of the second stop bank 102 is closer to the control rod 9 of the first stop bank 101 when viewed from the fuel assembly 8 of the new fuel 91.

  As described above, according to the present embodiment, when the reactor 2 is abnormal, the control rod 9 of the first stop bank 101 and the control rod 9 of the second stop bank 102 are inserted at different timings. By inserting it in 68, the reactor stop function by the control rod 9 of the first stop bank 101 and the reactor stop function by the control rod 9 of the second stop bank 102 can be exhibited. For this reason, since a plurality of reactor shutdown functions can be exhibited, it is possible to effectively utilize the control rod 9 and improve the reactor shutdown performance.

  Further, according to the present embodiment, when the reactor trips, the reactor 2 can be stopped by inserting the control rod 9 of the control bank 103 and the control rod 9 of the first stop bank 101 into the core 68. Even when the control rod 9 of the control bank 103 and the control rod 9 of the first stop bank 101 are inserted into the reactor core 68 and the reactor 2 shifts to the recritical state, the second stop bank 102 The control rod 9 can stop the reactor 2. For this reason, the safety of the nuclear reactor 2 can be improved. Here, the control rod 9 of the second stop bank 102 may be provided together with the boric acid water injection facility, or by providing the control rod 9 of the second stop bank 102 as an alternative function of the boric acid water injection facility, The boric acid water injection facility may be omitted.

  Further, according to the present embodiment, the configuration of the control rod 9 of the first stop bank 101 and the configuration of the control rod 9 of the second stop bank 102 can be made different. The stop function and the reactor stop function of the second stop bank 102 can be made different, so that the versatility can be improved. For example, by inserting the control rod 9 of the second stop bank 102, which has a higher proportion of high-performance control rods than the first stop bank 101, into the core 68 of the reactor 2 that shifts to the recriticality, Can be quickly transferred to the subcritical state.

  Further, according to the present embodiment, the control rod 9 of the second stop bank 102 composed of the second high-performance control rod 97 is disposed adjacent to the new fuel 91, so that neutrons are favorably absorbed. Since the reaction can be suppressed, the reactor 2 can be suitably stopped.

  In addition, according to the present embodiment, the control rod 9 of the control bank 103 is arranged on the spent fuel, and it is possible to appropriately control the output of the nuclear reactor by inserting and removing this fuel.

  Further, according to the present embodiment, the reactor trip can be appropriately performed by the control bank 103 and the first stop bank 101 having a large number of the first high-performance control rods 95. The total number of control rods 9 in the control bank 103 and the first stop bank 101 is the number that can be shifted from the high temperature full power state to the high temperature stop state during the reactor trip, and the rest is the second stop. The number of control rods 9 in the bank 102 is preferably set.

  Further, according to the present embodiment, the fuel is disposed in the control bank 103, the first stop bank 101, and the second stop bank 102 with respect to the plurality of control rods 9 in an appropriate arrangement in consideration of the shutdown of the reactor 2. Can do.

  In this embodiment, the control rod 9 of the first stop bank 101 is inserted into the fuel assembly 8 when the reactor trips, and the control rod 9 of the second stop bank 102 is inserted when the reactor 2 is recritical. Although it inserted in the fuel assembly 8, if it is a different insertion timing which can improve the stop performance of the nuclear reactor 2, it will not specifically limit to this structure.

DESCRIPTION OF SYMBOLS 1 Nuclear power plant 2 Reactor 3a Cold leg 3b Hot leg 4 Steam generator 5 Pressurizer 6 Primary coolant pump 7 Containment vessel 8 Fuel assembly 9 Control rod 10 Reactor vessel 11 Steam pipe 12 Turbine 13 Condenser 14 Feed pipe 15 Water supply pump 16 Generator 20 Control rod drive device 30 Safety protection system 35 Reactor shutdown device 37 Reactor trip circuit breaker 68 Core 71 Control rod cluster 90 Control rod unit 91 New fuel 92 Used fuel 94 Standard control rod 95 No. 1 1 high performance control rod 97 second high performance control rod 101 first stop bank 102 second stop bank 103 control bank

Claims (9)

A plurality of control rods inserted into the reactor core;
A control rod driving device for driving a plurality of the control rods;
A control unit for controlling the driving of the control rod by the control rod driving device,
The plurality of control rods include a control bank including a plurality of the control rods for controlling the output of the nuclear reactor, and another partial plurality of the controls for stopping the output of the nuclear reactor. A stop bank consisting of bars,
The stop bank includes at least a first stop bank including a part of the control rods and a second stop bank including a part of the other control rods among the plurality of control rods in the stop bank. ,
The controller is
In the event of an abnormality in the reactor, the control rod of the first stop bank and the control rod of the second stop bank are inserted into the core at different insertion timings. apparatus. The controller is
Upon obtaining a reactor trip signal for shutting down the reactor, the control bank and the first stop bank are inserted into the core while the second stop bank is inserted into the core. The insertion of the control rod is not executed,
The control rod of the second stop bank is inserted into the core when a recriticality detection signal output when the reactor detects an event that becomes recriticality is acquired. The reactor shutdown apparatus according to 1. The control rod includes a first control rod and a second control rod having higher neutron absorption performance than the first control rod,
3. The reactor shutdown according to claim 1, wherein the control rod of the second stop bank has a larger proportion of the second control rod than the control rod of the first stop bank. 4. apparatus. The fuel contained in the core has different burnups,
The control rod of the second stop bank is arranged on a side closer to the control rod of the first stop bank with respect to the fuel having the smallest burnup. Reactor shutdown device. The newest burnup fuel is a new fuel that is newly loaded into the reactor at the time of refueling,
The reactor stop according to claim 4, wherein the control rod of the second stop bank is disposed adjacent to the new fuel.   The reactor stop device according to claim 5, wherein the control rod of the control bank is disposed in a fuel other than the new fuel.   The total number of control rods in the control bank and the number of control rods in the first stop bank is larger than the number of control rods in the second stop bank. Item 7. The reactor shutdown device according to any one of Items 1 to 6. A nuclear reactor shutdown method for shutting down the nuclear reactor by a control unit that controls driving of a plurality of control rods inserted into the core of the nuclear reactor,
The plurality of control rods include a control bank including a plurality of the control rods for controlling the output of the nuclear reactor, and another partial plurality of the controls for stopping the output of the nuclear reactor. A stop bank consisting of bars,
The stop bank includes at least a first stop bank including a part of the control rods and a second stop bank including a part of the other control rods among the plurality of control rods in the stop bank. ,
In the event of an abnormality in the reactor, the control rod of the first stop bank and the control rod of the second stop bank are inserted into the core at different insertion timings. Method. In a core design method for designing a loading pattern of fuel loaded in a nuclear reactor,
A plurality of control rods inserted into the core of the reactor include a control bank composed of a part of the plurality of control rods for controlling the output of the reactor, and another for stopping the output of the reactor. And a stop bank consisting of a plurality of the control rods,
The stop bank includes at least a first stop bank including a part of the control rods and a second stop bank including another part of the control rods among the plurality of control rods in the stop bank. ,
The new fuel that is newly loaded into the reactor at the time of fuel replacement is arranged so that the control rod of the second stop bank is closer to the control rod than the control rod of the first stop bank. A core design method characterized by the above.

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